VALVE TIMING ADJUSTMENT APPARATUS

Abstract

A main locking mechanism locks a phase at a main locking phase, at which an intake valve is closed at timing later than a bottom dead center, by inserting a main locking member into a main locking hole. A sub locking mechanism locks a phase at a sub locking phase advanced more than the main locking phase by inserting a sub locking member into a sub locking hole. A movable body disposed in the main locking hole reciprocates between an open position and a blocking position of the main locking hole. During a warm start of an engine, a driving source maintains the movable body at the open position at which the inserting of the main locking member into the main locking hole is maintained. In contrast, during a cold start of the engine, the driving source drives the movable body to the blocking position at which the main locking member is removed from the main locking hole.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2013-124062 filed on Jun. 12, 2013.

TECHNICAL FIELD

The present invention relates to a valve timing adjustment apparatus that adjusts valve timing of an intake valve which opens and closes a cylinder of an internal combustion engine.

BACKGROUND

In the related art, a hydraulic valve timing adjustment apparatus which adjusts valve timing of an intake valve using a pressure of a working fluid is widely known. Typically, the hydraulic valve timing adjustment apparatus includes a housing rotor and a vane rotor which rotate respectively in connection with a crank shaft and a cam shaft of an internal combustion engine, and when the vane rotor in the housing rotor receives a pressure of the working fluid, a relative rotational phase between the rotors changes. As a result of the change of the relative rotational phase, the valve timing is adjusted.

A Japanese patent document 1 (JP 4,161,356 B) discloses a type of the hydraulic valve timing adjustment apparatus of the internal combustion engine in which a rotational phase advanced more than the most retarded angle phase is regarded as an intermediate phase. When a rotational phase reaches the intermediate phase, the rotational phase is locked during the starting of the internal combustion engine. The closing timing of the intake valve becomes as quickly as possible by the locking function. As a result, an actual compression ratio of the cylinder increases and a temperature of gas in the cylinder increases by compression heating, and thus, fuel vaporization is promoted. Accordingly, startability can be ensured during the cold start of the internal combustion engine that is left in a stop state under a low temperature condition such as an extremely low temperature condition.

However, in the hydraulic valve timing adjustment apparatus with early closing timing of the intake valve disclosed in the patent document 1, there is a concern in that the following problems may occur due to the actual high compression ratio of the cylinder during the warm start of the internal combustion engine under a comparatively high temperature condition such as a normal temperature condition. One of the problems is occurrence of knocking. Another problem occurs during the re-starting of the internal combustion engine applied to an idle stop system or a hybrid system, or during the re-starting of the engine immediately after an engine is stopped by a turn-off of an ignition switch. A temperature of gas in the cylinder excessively increases during compression, thereby causing pre-ignition in which the gas undergoes self-ignition before being ignited, or a compressive reaction force becomes great and variation of a cranking rotation increases, thereby causing an unpleasant vibration or a noise.

In addition, a hydraulic valve timing adjustment apparatus disclosed in a patent document 2 (JP 2002-256910 A) selects one of the following two phases during the starting of the internal combustion engine: a retarded angle phase set so as to close the intake valve at timing later than when a piston reaches a bottom dead center of the cylinder; and an intermediate phase advanced more than the retarded angle phase. A start optimized for a temperature (hereinafter, referred to as an “engine temperature”) of the internal combustion engine can be ensured by the selection of the rotational phase.

In the hydraulic valve timing adjustment apparatus disclosed in the patent document 2, a pressure of the working fluid is imparted on the vane rotor in the housing rotor during the warm start of the internal combustion engine. Accordingly, the rotational phase is not locked, and the retarded angle phase is selected by the adjustment of the rotational phase. For this reason, during the start during which the pressure of the working fluid is reduced, the vane rotor rotates to advance relative to the housing rotor by a variable torque from the cam shaft, and the rotational phase is likely to shift from the retarded angle phase.

In the hydraulic valve timing adjustment apparatus disclosed in the patent document 2, since a variable torque causes the rotational phase to change to the intermediate phase during the cold start of the internal combustion engine, the working fluid imparting a pressure on the vane rotor in the housing rotor is drained. As a result, the working fluid imparting a pressure on a locking body is also drained. Accordingly, the locking body moves to a locking release position, and the rotational phase is difficult to be locked at the intermediate phase.

SUMMARY

The present disclosure is made in light of the problems described above, and an object of the present disclosure is to provide a hydraulic valve timing adjustment apparatus with which an engine start optimized for an engine temperature is realized.

In a first aspect of the present disclosure, a valve timing adjustment apparatus that adjusts valve timing of an intake valve, which opens and closes a cylinder of an internal combustion engine, by a pressure of a working fluid. The valve timing adjustment apparatus includes a housing rotor that rotates in connection with a crank shaft of the internal combustion engine and a vane rotor that rotates in connection with a cam shaft of the internal combustion engine. A rotational phase of the vane rotor relative to the housing rotor is changed by receiving the pressure of the working fluid in the housing rotor. The apparatus further includes a main locking portion that has a main locking member and a main locking hole. The main locking portion locks the rotational phase to a main locking phase, at which the intake valve is closed at timing later than when a piston in the cylinder reaches a bottom dead center of the cylinder, by inserting the main locking member into the main locking hole when the rotational phase is the main locking phase during the starting of the internal combustion engine. A sub locking portion has a sub locking member and a sub locking hole. The sub locking portion locks the rotational phase to a sub locking phase, which is advanced more than the main locking phase, by inserting the sub locking member into the sub locking hole when the rotational phase is changed from the main locking phase to the sub locking phase during the starting of the internal combustion engine. A movable body is disposed in the main locking hole to reciprocate between an open position at which the movable body opens the main locking hole and a blocking position at which the movable body blocks the main locking hole. A determination portion determines a warm start when a temperature of the internal combustion engine is equal to or higher than a specific temperature and a cold start when a temperature of the internal combustion engine is lower than the specific temperature. A driving source maintains the movable body at the open position, at which the main locking member is inserted into the main locking hole, when the determination portion determines the warm start, and drives the movable body to the blocking position, at which the main locking member is removed from the main locking hole, when the determination portion determines the cold start.

According to the first aspect the present disclosure, during the warm start of the internal combustion engine during which it is determined that the engine temperature is equal to or higher than the specific temperature, the movable body, which opens or closes the main locking hole by reciprocating in the main locking hole, is maintained at the open position. As a result, since the inserting of the main locking member into the main locking hole is maintained at the main locking phase during the starting of the internal combustion engine, the rotational phase remains locked at the main locking phase. Herein, at the main locking phase at which the intake valve is closed at timing later than when the piston reaches the bottom dead center of the cylinder, gas in the cylinder is pushed into an intake system as the piston lifts up from the bottom dead center, and thus an actual compression ratio decreases. Accordingly, during the warm start, the rotational phase is retained at the main locking phase, and occurrence of a starting failure (herein after, simply referred to as a “starting failure”) such as knocking, pre-ignition, an unpleasant vibration or a noise is suppressed.

In contrast, during the cold start of the internal combustion engine during which it is determined that the engine temperature is lower than the specific temperature, the movable body is driven to the blocking position. Since the main locking member is removed from the main locking hole at the main locking phase during the starting of the internal combustion engine, the locking of the rotational phase is released. At this time, the vane rotor, which receives a variable torque from the cam shaft, rotates in an advance direction relative to the housing rotor, and thus the rotational phase is changed to the sub locking phase advanced more than the main locking phase. As a result, the sub locking member is inserted into the sub locking hole and the rotational phase is locked at the sub locking phase, and thus a closing timing of the intake valve becomes as quickly as possible. Accordingly, the amount of gas being pushed out of the cylinder decreases, and a temperature of the gas increases together with the actual compression ratio, and thus even during the cold start, ignitability improves and startability can be ensured.

According to the present disclosure described above, a start optimized for the engine temperature can be realized.

In a second aspect of the present disclosure, the movable body has a protruding end portion that protrudes to an outside of the housing rotor from the main locking hole when the movable body is at the open position. The driving source has a drive shaft disposed outside the housing rotor that presses the protruding end portion at the open position toward the blocking position during the cold start.

According to the second aspect of the present disclosure, during the cold start, the drive shaft outside the housing rotor presses the protruding end portion of the movable body when the movable body is at the open position, which protrudes to the outside of the housing rotor from the main locking hole. As a result, not only the movable body is reliably driven to the blocking position so that the locking of the rotational phase can be released, but also the drive shaft is prevented from interfering with a rotation of the vane rotor in the housing rotor relative to the housing rotor so that the rotational phase can smoothly change to the sub locking phase. Accordingly, the time period which it takes from when a variable torque is generated during cranking of the cold start of the internal combustion engine until when the rotational phase is locked at the sub locking phase can be shortened, and thus reliability can be improved particularly in cold startability.

In a third aspect of the present disclosure, the housing rotor and the vane rotor rotate around an axis, and the movable body reciprocates in a direction parallel to the axis of the housing rotor and the vane rotor. The protruding end portion has a tapered outer circumferential surface having a diameter that decreases toward a distal end of the protruding end portion. The drive shaft is supported by a stationary component of the internal combustion engine, and the driving source withdraws the drive shaft from a rotation region of the protruding end portion during the warm start and advances the drive shaft into the rotation region during the cold start.

According to the third aspect of the present disclosure, during the warm start, the drive shaft withdraws from the rotation region of the protruding end portion, and thus the movable body is not pressed by the drive shaft and can be reliably maintained at the open position. In contrast, during the cold start, the drive shaft supported by the stationary component of the internal combustion engine advances into the rotation region of the protruding end portion, and thus the movable body is brought into contact with the outer circumferential surface of the protruding end portion as the housing rotor rotates. At this time, since the drive shaft is brought into contact with the taper-shaped outer circumferential surface of the protruding end portion the diameter of which gradually decreases toward the distal end, the movable body receives a partial force from the drive shaft in the direction of movement of the movable body which is along the common axial direction of the housing rotor and the vane rotor, and the movable body can be reliably pressed and driven toward the blocking position. Accordingly, the movable body can accurately move to the open position at which the locking of the rotational phase is retained at the main locking position, or to the blocking position at which the locking of the rotational phase is released. As a result, when the rotational phase is switched to a rotational phase optimized for each of the warm start and the cold start, reliability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings, in which:

FIG. 1 is a view illustrating a basic configuration of a valve timing adjustment apparatus according to First Embodiment of the present disclosure, and a cross-sectional view taken along line I-I in FIG. 2;

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a cross-sectional view illustrating an operation state different from the operation state in FIG. 2;

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a schematic view illustrating an operation state of the valve timing adjustment apparatus of FIG. 1;

FIG. 6 is a schematic view illustrating an operation state different from the operation state in FIG. 5 of the valve timing adjustment apparatus of FIG. 1;

FIG. 7 is a schematic view illustrating an operation state different from the operation states in FIGS. 5 and 6 of the valve timing adjustment apparatus of FIG. 1;

FIG. 8 is a schematic view illustrating an operation state different from the operation states in FIGS. 5 to 7 of the valve timing adjustment apparatus of FIG. 1;

FIG. 9 is a schematic view describing characteristics of the valve timing adjustment apparatus of FIG. 1;

FIG. 10 is a graph describing the characteristics of the valve timing adjustment apparatus of FIG. 1;

FIG. 11 is a perspective view illustrating main parts of the valve timing adjustment apparatus of FIG. 1;

FIG. 12 is a cross-sectional view taken along line I-I in FIG. 2 to correspond to the operation state in FIG. 5;

FIG. 13 is a cross-sectional view taken along line I-I in FIG. 2 to correspond to the operation state in FIG. 6;

FIG. 14 is a schematic view describing an operation of the valve timing adjustment apparatus of FIG. 1;

FIG. 15 is a characteristic graph describing a variable torque that acts on the valve timing adjustment apparatus of FIG. 1;

FIG. 16 illustrates graphs describing an example of an operation of the valve timing adjustment apparatus of FIG. 1;

FIG. 17 illustrates graphs describing an example of an operation different from the operation in FIG. 16 of the valve timing adjustment apparatus of FIG. 1;

FIG. 18 is a flow chart illustrating a control flow executed by the valve timing adjustment apparatus of FIG. 1 during the starting of an internal combustion engine;

FIG. 19 is a schematic view illustrating unique portions of a valve timing adjustment apparatus according to Second Embodiment of the present disclosure;

FIG. 20 is a schematic view describing an operation of the valve timing adjustment apparatus of FIG. 19;

FIG. 21 is a schematic view describing the operation of the valve timing adjustment apparatus of FIG. 19; and

FIG. 22 is a schematic view illustrating a modification example of the valve timing adjustment apparatus of FIG. 14.

DETAILED DESCRIPTION

Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the accompanying drawings. There is a case where the same reference signs are assigned to the corresponding configuration elements in each embodiment, and duplicated descriptions of the configuration elements will be omitted. When only a portion of a configuration of each embodiment is described, other portions of the configuration can be described using configurations of the other embodiments, which are previously described. In the description of each embodiment, the present disclosure is not limited only to a combination of the configuration which is specified, but also the configurations of the plurality of embodiments can be partially combined even if not specified insofar as there is no obstacle to the combination of the configurations.

First Embodiment

As illustrated in FIG. 1, a valve timing adjustment apparatus 1 according to the First Embodiment of the present disclosure is mounted on an internal combustion engine of a vehicle. In the embodiment, the internal combustion engine is stopped and started not only by an ON command or an OFF command of an engine switch SW but also by an idle stop command or a re-starting command of an idle stop system ISS.

(Basic Configuration)

First, a basic configuration of the valve timing adjustment apparatus 1 will be described. The apparatus 1 is a hydraulic type that uses a pressure of a working oil as a “pressure of a working fluid”, and adjusts valve timing of an intake valve 9 (refer to FIG. 10 to be described later) as a “moving valve” that a cam shaft 2 opens or closes via transmission of an engine torque. The apparatus 1 illustrated in FIGS. 1 to 8 includes a rotation drive unit 10 that is disposed in a transmission system which transmits an engine torque output from a crank shaft (not illustrated) to the cam shaft 2 in the internal combustion engine, and a control unit 40 that controls inflow and outflow of the working oil to drive the drive unit 10.

(Rotation Drive Unit)

The rotation drive unit 10 includes rotors 11 and 14 and locking members 160 and 170.

As illustrated in FIGS. 1 and 2, the metallic housing rotor 11 includes a rear plate 13 and a front plate 15 that are respectively tightened with each end portion of a shoe ring 12 in an axial direction. The rear plate 13 has cylindrical locking holes 162 and 172 formed to be open toward the vane rotor 14 within the shoe ring 12.

The shoe ring 12 has a cylindrical housing main body 120, a plurality of shoes 121, 122 and 123 and a sprocket 124. As illustrated in FIG. 2, the shoes 121, 122 and 123 protrude inward in a radial direction from locations of the housing main body 120, which are apart in a rotational direction with a predetermined gap therebetween. Accommodation chambers 20 are respectively formed between the shoes 121 and 122, the shoes 122 and 123, and the shoes 123 and 121 each pair of which is adjacent in the rotational direction to each other. The sprocket 124 is connected to the crank shaft via a timing chain (not illustrated). Through this connection, an engine torque is transmitted from the crank shaft to the sprocket 124 while the internal combustion engine rotates. Accordingly, the housing rotor 11 rotates in a constant direction (in a clockwise direction in FIG. 2) in connection with the crank shaft.

As illustrated in FIGS. 1 and 2, the metallic vane rotor 14 is coaxially housed inside the housing rotor 11. The metallic vane rotor 14 and the housing rotor 11 rotate around an axis. Both end portions in the axial direction of the vane rotor 14 slide against the rear plate 13 and the front plate 15, respectively. The vane rotor 14 has a cylindrical rotary shaft 140 and a plurality of vanes 141, 142 and 143. The rotary shaft 140 is coaxially fixed to the cam shaft 2. With this, the vane rotor 14 can rotate in connection with the cam shaft 2 in the same direction (in the clockwise direction in FIG. 2) as that of the housing rotor 11, and the vane rotor 14 can rotate relative to the housing rotor 11.

As illustrated in FIG. 2, the vanes 141, 142 and 143 protrude outward in the radial direction from locations of the rotary shaft 140, which are apart in the rotational direction with a predetermined gap therebetween, and each of the vanes 141, 142 and 143 is housed in the corresponding accommodation chamber 20. Each of the vanes 141, 142 and 143 divides the corresponding accommodation chamber 20 in the rotational direction, and partitions advance chambers 22, 23 and 24 which the working oil flows into or out of and retard chambers 26, 27 and 28 which the working oil flows into or out of in the housing rotor 11. Specifically, the advance chamber 22 is formed between the shoe 121 and the vane 141, the advance chamber 23 is formed between the shoe 122 and the vane 142, and the advance chamber 24 is formed between the shoe 123 and the vane 143. The retard chamber 26 is formed between the shoe 122 and the vane 141, the retard chamber 27 is formed between the shoe 123 and the vane 142, and the retard chamber 28 is formed between the shoe 121 and the vane 143.

As illustrated in FIGS. 1 and 2, the vane 141 supports the cylindrical metallic main locking member 160 in such a manner that the main locking member 160 can reciprocate in a direction parallel to the axis of the rotors 11 and 14. In addition, the vane 141 forms a main locking release chamber 161 around the main locking member 160. The main locking release chamber 16 is an annular space which the working oil flows into or out of. As illustrated in FIGS. 1 and 5, when the working oil is discharged out of the main locking release chamber 161, the main locking member 160 is inserted into the main locking hole 162. The main locking member 160 locks a rotational phase (hereinafter, simply referred to as a “rotational phase”) of the vane rotor 14 relative to the housing rotor 11 at a main locking phase Pm by the inserting. In contrast, as illustrated in FIGS. 6 to 8, the main locking member 160 is removed from the main locking hole 162 by receiving a pressure of the working oil introduced into the main locking release chamber 161. The main locking member 160 releases the rotational phase locked at the main locking phase Pm when the main locking member 160 is removed from the main locking hole 162.

As illustrated in FIGS. 3 and 4, the vane 142 supports the cylindrical metallic sub locking member 170 in such a manner that the sub locking member 170 can reciprocate in a direction parallel to the axis of the rotors 11 and 14. The vane 142 forms a sub locking release chamber 171 around the sub locking member 170. The sub locking release chamber 171 is an annular space which the working oil flows into or out of. As illustrated in FIGS. 4 and 7, when the working oil is discharged out of the sub locking release chamber 171, the sub locking member 170 is inserted into the sub locking hole 172. The sub locking member 170 locks a rotational phase of the vane rotor 14 at a sub locking phase Ps when the sub locking member 170 is inserted into the sub locking hole 172. In contrast, as illustrated in FIGS. 5, 6 and 8, the sub locking member 170 is removed from the sub locking hole 172 by receiving a pressure of the working oil introduced into the sub locking release chamber 171. The sub locking member 170 releases the rotational phase locked at the sub locking phase Ps when the sub locking member 170 is removed from the sub locking hole 172.

In the rotation drive unit 10, when the vane rotor 14 in the housing rotor 11 receives a pressure of the working oil flowing into or out of the advance chambers 22, 23 and 24 and the retard chambers 26, 27 and 28 under the release of the locking of the rotational phase, valve timing is adjusted. Specifically, when the working oil is introduced into the advance chambers 22, 23 and 24, and the working oil is discharged out of the retard chambers 26, 27 and 28, the rotational phase changes to advance (for example, a change from a state in FIG. 2 to a state in FIG. 3). As a result, the valve timing is adjusted to advance. When the working oil is introduced into the retard chambers 26, 27 and 28, and the working oil is discharged out of the advance chambers 22, 23 and 24, the rotational phase changes to retard (for example, a change from the state in FIG. 3 to the state in FIG. 2). As a result, the valve timing is adjusted to retard. When the working oil is enclosed in the advance chambers 22, 23 and 24, and the retard chambers 26, 27 and 28, a change of the rotational phase is suppressed, and the valve timing is adjusted to be retained at a substantially constant value.

(Control Unit)

As illustrated in FIGS. 1 and 5, the control unit 40 includes passages 41, 45, 49, 50, 52 and 54, a control valve 60 and a control circuit 80.

The main advance passage 41 is formed in the rotary shaft 140, and communicates with the advance chambers 22, 23 and 24. The main retard passage 45 is formed in the rotary shaft 140, and communicates with the retard chambers 26, 27 and 28. The locking release passage 49 is formed in the rotary shaft 140, and communicates with both of the locking release chambers 161 and 171.

The main supply passage 50 is formed in the rotary shaft 140, and communicates with a pump 4 as a supply source via a transportation passage 3. Herein, the pump 4 is a mechanical pump that is driven by receiving an engine torque during the rotation of the internal combustion engine. The pump 4 continuously discharges the working oil suctioned from a drain pan 5 during the rotation. The transportation passage 3 passes through the cam shaft 2 and a bearing thereof, and can always communicate with a discharge port of the pump 4 regardless of rotation of the cam shaft 2. In such a configuration, when the internal combustion engine starts by cranking to reach a complete combustion, the pump 4 starts supplying the working oil to the main supply passage 50. In contrast, when the internal combustion engine is stopped, the supply of the working oil is stopped.

The sub supply passage 52 is formed in the rotary shaft 140, and branches from the main supply passage 50. The sub supply passage 52 receives the working oil supplied from the pump 4 via the main supply passage 50. The drainage recovery passage 54 is provided outside the rotation drive unit 10 and the cam shaft 2. The drainage recovery passage 54 and the drain pan 5 as a drainage recovery unit are open to the air, and the working oil can be discharged to the drain pan 5.

In the embodiment, the control valve 60 is an electromagnetic spool valve. The control valve 60 makes use of a driving force which is generated by energizing a linear solenoid 62 and a restoring force which is generated in opposition to a direction of the driving force by an elastic deformation of a biasing member 64. The control valve 60 connecting to each of the passages 41, 45, 49, 50, 52 and 54 switches communication between the passages by reciprocating in the axial direction a spool 68 inside a sleeve 66 illustrated in FIGS. 1 and 2. Specifically, when the spool 68 moves to a locking region R1 which is illustrated in FIGS. 5 to 7, the working oil is introduced from the pump 4 into the retard chambers 26, 27 and 28, and the working oil in the advance chambers 22, 23 and 24 and the locking release chambers 161 and 171 is discharged to the drain pan 5. When the spool 68 moves to a retard region Rr which is illustrated in FIG. 8, the working oil in the advance chambers 22, 23 and 24 is discharged to the drain pan 5, and the working oil is introduced from the pump 4 into the retard chambers 26, 27, 28 and the locking release chambers 161 and 171. When the spool 68 moves to an advance region Ra which is illustrated in FIG. 8, the working oil in the retard chambers 26, 27 and 28 is discharged to the drain pan 5, and the working oil is introduced from the pump 4 into the advance chambers 22, 23, 24 and the locking release chambers 161 and 171. When the spool 68 moves to a retention region Rh which is illustrated in FIG. 8, the working oil is introduced from the pump 4 into the locking release chambers 161 and 171, and the working oil is enclosed in the advance chambers 22, 23 and 24 and the retard chambers 26, 27 and 28.

The control circuit 80 is a micro computer that is electrically connected to the linear solenoid 62, the engine switch SW, various electrical components of the internal combustion engine and the like as illustrated in FIG. 1. The control circuit 80 is a configuration component of the idle stop system ISS. The control circuit 80 controls the energization of the linear solenoid 62 and an operation of the internal combustion engine, which includes idle stop, based on a computer program.

(Main Locking Mechanism)

Subsequently, a main locking mechanism 16 illustrated in FIG. 1 as “main locking portion” will be described. The main locking mechanism 16 includes a main elastic member 163, which is provided in the rotation drive unit 10 and combined with a set of the main locking elements 160, 161 and 162.

As illustrated in FIG. 5, the main elastic member 163 is a metallic coil spring, and is housed in the vane 141. The main elastic member 163 is installed between spring receiving portions 141a and 160a which are respectively provided in the vane 141 and the main locking member 160. Since the main elastic member 163 is installed between the spring receiving portions 141a and 160a, the main elastic member 163 generates a restoring force to bias the main locking member 160 toward the rear plate 13. Accordingly, a restoring force of the main elastic member 163 at the main locking phase Pm as illustrated in FIGS. 5 and 6 becomes a biasing force that acts in a direction in which the main locking member 160 is inserted into the main locking hole 162. A driving force caused by a pressure in the main locking release chamber 161 drives the main locking member 160 against the restoring force of the main elastic member 163, and the driving force at the main locking phase Pm acts in a direction in which the main locking member 160 is removed from the main locking hole 162.

In the aforementioned configuration, the main locking phase Pm which occurs by inserting the main locking member 160 into the main locking hole 162 is preset to the most retard angle phase as illustrated in FIGS. 2 and 9. As illustrated in FIG. 10, the main locking phase Pm particularly in the embodiment is preset to a rotational phase at which the intake valve 9 is closed at timing later than when a piston 8 reaches a bottom dead center BDC in a cylinder 7 of the internal combustion engine.

(Sub Locking Mechanism)

Subsequently, a sub locking mechanism 17 which is illustrated in FIG. 4 as “sub locking portion” will be described. The sub locking mechanism 17 is constituted by combining a sub elastic member 173 and a limiting groove 174, which are provided in the rotation drive unit 10, into a set of the sub locking elements 170, 171 and 172.

As illustrated in FIG. 5, the sub elastic member 173 is a metallic coil spring, and is housed in the vane 142. The sub elastic member 173 is installed between spring receiving portions 142a and 170a which are respectively provided in the vane 142 and the sub locking member 170. Since the sub elastic member 173 is installed between the spring receiving portions 142a and 170a, the sub elastic member 173 generates a restoring force to bias the sub locking member 170 toward the rear plate 13. Accordingly, a restoring force of the sub elastic member 173 at the sub locking phase Ps illustrated in FIGS. 7 and 8 serves as a biasing force that acts in a direction in which the sub locking member 170 is inserted into the sub locking hole 172. A driving force caused by a pressure in the sub locking release chamber 171 drives the sub locking member 170 against the restoring force of the sub elastic member 173, and the driving force at the sub locking phase Ps acts in a direction in which the sub locking member 170 is removed from the sub locking hole 172.

As illustrated in FIGS. 2, 3 and 5, the limiting groove 174 is formed on the rear plate 13 in a bottomed long hole shape, and extends in a circular arc shape along the common rotational direction of the rotors 11 and 14. The sub locking hole 172 is opened in a groove bottom of an intermediate portion of the limiting groove 174. When the sub locking member 170 enters into the limiting groove 174 from both sides in the rotational direction of the sub locking hole 172, an opening structure of the sub locking hole 172 limits a rotational phase within a given rotational phase region within which the sub locking phase Ps is interposed. When the rotational phase reaches the sub locking phase Ps, the sub locking member 170 is inserted into the sub locking hole 172 within the limiting groove 174, whereby locking the rotational phase at the sub locking phase Ps as illustrated in FIG. 7.

In the aforementioned configuration, the sub locking phase Ps realized by inserting the sub locking member 170 into the sub locking hole 172 is preset to the intermediate phase advanced more than the main locking phase Pm as illustrated in FIGS. 3 and 9. As illustrated in FIG. 10, the sub locking phase Ps particularly in the embodiment is preset to a rotational phase for closing the intake valve 9 at timing when the piston 8 reaches the bottom dead center BDC of the cylinder 7 of the internal combustion engine or at timing when the piston 8 reaches the vicinity of the bottom dead center BDC.

(Locking Control System)

Subsequently, a locking control system 18 which is illustrated in FIG. 1 will be described. The locking control system 18 includes a movable body 181, which is provided in the rotation drive unit 10, and a driving source 182 provided in the control unit 40 into the control circuit 80.

The columnar metallic movable body 181 is coaxially disposed within the main locking hole 162, and can reciprocate in a direction parallel to the axis of the rotors 11 and 14. Herein, as illustrated in FIGS. 5, 11 and 12, the main locking hole 162 passes through the rear plate 13 and is also opened to a side opposite to the vane rotor 14. The movable body 181 protrudes toward the outside of the housing rotor 11 from the main locking hole 162 via an opening 162a on the opposite side. Accordingly, one end portion of the movable body 181 forms a protruding end portion 183 which protrudes to the outside of the housing rotor 11 at a moving position. In the embodiment, the protruding end portion 183 has a taper-shaped (cone-shaped) outer circumferential surface 183a having a diameter that gradually decreases toward the distal end.

As illustrated in FIGS. 5 and 12, the other end portion of the movable body 181 forms a housed end portion 184 that is housed in the main locking hole 162 at a moving position. A portion of the movable body 181 including at least the housed end portion 184 is slidably fitted into the main locking hole 162 to suppress the leaking of the working oil from the housing rotor 11 to the outside via the hole 162. In the embodiment, the housed end portion 184 has a circular flat tip surface 184a that is substantially concentric with a cross-sectional surface of the main locking hole 162.

An annular flange-shaped retaining portion 185 is provided between both end portions 183 and 184 of the movable body 181. Herein, stopper portions 162b and 162c are formed on both sides of the main locking hole 162 to interpose the retaining portion 185 therebetween in a direction of movement of the movable body 181. The stopper portions 162b and 162c can lock the retaining portion 185 depending on the moving position of the movable body 181.

When the movable body 181 having the above-described configuration moves to a blocking position Lc as illustrated in FIGS. 6, 7 and 13, the movable body 181 substantially blocks an opening 162d on a vane rotor 14 side of the main locking hole 162. Because of the blockage, the main locking member 160 at the main locking phase Pm illustrated in FIGS. 6 and 13 is blocked by the tip surface 184a of the movable body 181, and thus the main locking member 160 is removed from the main locking hole 162, that is, the locking of the rotational phase is released. At this time, the retaining portion 185 is locked by the stopper portion 162b, and thus the movable body 181 in the main locking hole 162 is prevented from falling out from the opening 162d.

In contrast, when the movable body 181 moves to an open position Lo as illustrated in FIGS. 5, 8 and 12, which is shifted from the blocking position Lc to the side opposite to the vane rotor 14, the movable body 181 opens the opening 162d. Because of the opening, the main locking member 160 at the main locking phase Pm as illustrated in FIGS. 5 and 12 is inserted into the main locking hole 162 until being brought into contact with the tip surface 184a of the movable body 181, and thus the rotational phase is locked. At this time, the retaining portion 185 is locked by the stopper portion 162c particularly at a maximum open position Lomax of the open position Lo, at which the main locking hole 162 is the most widely opened, and thus the movable body 181 in the main locking hole 162 is prevented from falling out from the opening 162a.

As illustrated in FIGS. 1 and 11, the driving source 182 in the embodiment is a linear solenoid, and has a fixation casing 189, a drive shaft 186 and a drive coil 188. The hollow metallic fixation casing 189 is fixed to a stationary component (for example, a cylinder head or the like) of the internal combustion engine. The columnar metallic drive shaft 186 is disposed outside the housing rotor 11, and is supported by the stationary component via the fixation casing 189. The drive coil 188 is constituted by winding a metallic wire, and is housed inside the fixation casing 189. The drive shaft 186 is driven to reciprocate along the radial direction of the rotors 11 and 14 based on a control of energization of the drive coil 188.

As illustrated in FIGS. 12 and 13, a tip portion 187 is formed with a cylindrical outer circumferential surface 187a in the drive shaft 186 of the embodiment, and the tip portion 187 can advance and retreat with respect to a rotation region Ar of the protruding end portion 183 of the movable body 181 that rotates integrally with the housing rotor 11. Herein, the rotation region Ar is defined by deriving a locus of the taper-shaped protruding end portion 183 rotating with the housing rotor 11 across the entire moving positions of the movable body 181.

As illustrated in FIGS. 6, 13 and 14, when the drive shaft 186 is driven to an advance position Li at which the tip portion 187 advances into the rotation region Ar, the outer circumferential surface 187a of the tip portion 187 is brought into contact with the protruding end portion 183 as the housing rotor 11 rotates. Herein, in particular, when the movable body 181 is present at the maximum open position Lomax as illustrated in FIG. 14, and the cylindrical outer circumferential surface 187a is brought into contact with the taper-shaped outer circumferential surface 183a, the protruding end portion 183 receives a partial force F that acts toward the blocking position Lc in a direction of movement of the movable body 181, which is parallel to the axis of the rotors 11 and 14. At this time, the protruding end portion 183 at the main locking phase Pm is pressed toward the blocking position Lc by the drive shaft 186. As a result, the housed end portion 184 presses the main locking member 160 against the restoring force of the main elastic member 163, and thus the main locking member 160 can be removed from the main locking hole 162.

In contrast, as illustrated in FIGS. 5, 7, 8 and 12, when the drive shaft 186 is driven to a retreat position Le at which the tip portion 187 withdraws from the rotation region Ar, the end portions 187 and 183 are not brought into contact with each other regardless of the rotation of the housing rotor 11. Herein, in particular, the housed end portion 184 at the main locking phase Pm as illustrated in FIG. 5 is pressed by a pressure of the working oil in the advance chamber 22 or the retard chamber 26, or by the main locking member 160 which receives the restoring force of the main elastic member 163. Accordingly, the movable body 181 is driven to the open position Lo. At this time, the movable body 181 is pressed and can be driven to the maximum open position Lomax by the main locking member 160 that receives the restoring force of the main elastic member 163 in a state where a pressure loss in the main locking release chamber 161 occurs.

As illustrated in FIG. 1, the control circuit 80 is electrically connected to the drive coil 188. During the starting of the internal combustion engine, the control circuit 80 as “determination portion” determines which one of an engine temperature and a specific temperature Ts (refer to FIGS. 16 and 17 to be described later) is high, and controls the energization of the drive coil 188 based on the determination result. Thus, the control circuit 80 determines a warm start when the engine temperature is equal to or higher than the specific temperature and a cold start when the engine temperature is lower than the specific temperature. Herein, the engine temperature is acquired based on information of a temperature detected by a temperature sensor such as a coolant temperature sensor or an oil temperature sensor which is mounted on the vehicle. For example, the specific temperature Ts is preset to a temperature in a range of 40° C. to 60° C. to appropriately discriminate a warm start at the specific temperature Ts or higher from a cold start at less than the specific temperature Ts. However, the specific temperature Ts may be preset to another temperature.

(Action of Variable Torque on Vane Rotor)

Subsequently, a variable torque which acts on the vane rotor 14 from the cam shaft 2 will be described.

During the rotation of the internal combustion engine, the variable torque acts on the vane rotor 14 by a spring reaction force from the intake valve 9 the opening and closing of which is driven by the cam shaft 2. As exemplified in FIG. 15, the variable torque alternates between a negative torque that acts in an advance direction relative to the housing rotor 11 and a positive torque that acts in a retard direction relative to the housing rotor 11. With regard to the variable torque of the embodiment, a positive peak torque becomes greater than a negative peak torque due to friction between the cam shaft 2 and the bearing thereof and the like, and an average torque is offset to a positive torque side (in a retard direction).

(Biasing Structure of Vane Rotor)

Subsequently, a biasing structure for biasing the vane rotor 14 toward the sub locking phase Ps will be described.

In the rotation drive unit 10 which is illustrated in FIG. 1, the rotors 11 and 14 are respectively provided with locking pins 110 and 146. The first locking pin 110 is formed in a columnar shape on the front plate 15 to protrude toward a side opposite to the shoe ring 12 in the axial direction. The second locking pin 146 is formed in a columnar shape on the rotary shaft 140 to protrude in the axial direction toward the plate 15 from an arm plate 147 substantially in parallel to the front plate 15. The locking pins 110 and 146 are disposed at locations that are offset at substantially the same distance from rotation center lines of the rotors 11 and 14, respectively, and are shifted in the axial direction from each other.

An advance angle elastic member 19 is disposed between the front plate 15 and the arm plate 147. The advance angle elastic member 19 is formed by winding a metallic plate into a helical shape on substantially the same plane, and the center of the helical shape is aligned with the rotation center lines of the rotors 11 and 14. An innermost circumferential portion of the advance angle elastic member 19 is mounted in a winding manner on an outer circumferential portion of the rotary shaft 140. An outermost circumferential portion of the advance angle elastic member 19 is bent in a U shape to form a locking portion 190. Any one of the locking pins 110 and 146 can lock the locking portion 190 based on the rotational phase.

In the aforementioned configuration, when the rotational phase changes to an angle retarded more than the sub locking phase Ps, that is, an angle between the locking phases Ps and Pm, the locking portion 190 is locked by the first locking pin 110. At this time, since the second locking pin 146 deviates from the locking portion 190, a restoring force of the advance angle elastic member 19 generated from a torsional elastic deformation acts on the vane rotor 14 as a rotational torque in the advance direction relative to the housing rotor 11. That is, the vane rotor 14 is biased in the advance direction toward the sub locking phase Ps. The restoring force of the advance angle elastic member 19 is preset to be greater than an average value of the variable torque (refer to FIG. 15) that is offset in the retard direction between the locking phases Ps and Pm. In contrast, when the rotational phase changes to an angle advanced more than the sub locking phase Ps, the locking portion 190 is locked by the second locking pin 146. At this time, since the first locking pin 110 deviates from the locking portion 190, the biasing of the vane rotor 14 by the advance angle elastic member 19 is limited.

(Operation)

Subsequently, the entire operation of the apparatus 1 according to a control process of the control circuit 80 will be described.

(1) Normal Operation

During a normal operation of the internal combustion engine after the start and the complete combustion, the spool 68 moves to any one of regions Rr, Ra and Rh. At this time, as illustrated in FIGS. 16 and 17, the pump 4 continuously supplies the working oil at a high pressure according to a rotational speed of the internal combustion engine. As a result, the main locking member 160 is removed from the main locking hole 162 against the restoring force of the main elastic member 163 by a pressure of the working oil introduced into the main locking release chamber 161 (refer to FIG. 8). In addition, the sub locking member 170 is removed from the sub locking hole 172 and the limiting groove 174 against the restoring force of the sub elastic member 173 by a pressure of the working oil introduced into the sub locking release chamber 171 (refer to FIG. 8). As results of the removals, the releases of both locking phases Pm and Ps are maintained, and valve timing is appropriately adjusted based on a moving position of the spool 68, which corresponds to any one of the regions Rr, Ra and Rh.

During the normal operation, since a pressure of the main locking release chamber 161 acts on the main locking member 160, the release of the main locking phase Pm is maintained regardless of a moving position of the movable body 181. During the normal operation, since the drive shaft 186 is driven to the retreat position Le by a control of energization of the drive coil 188, the movable body 181 receives a high pressure of the working oil in the advance chamber 22 or the retard chamber 26 to move to the maximum open position Lomax (refer to FIG. 8).

(2) Stop and Start

As illustrated in FIGS. 16 and 17, an operation of the internal combustion engine is changed to a stop operation from a normal operation based on a stop command such as an OFF command of the engine switch SW or an idle stop command of the idle stop system ISS. During the stop operation, before the internal combustion engine inertially rotates by a fuel cut-off, the spool 68 moves to a locking region R1. At this time, the pump 4 continuously supplies the working oil at a high pressure according to a rotational speed of the internal combustion engine. Accordingly, the rotational phase changes to the main locking phase Pm as the most retarded angle phase by a pressure of the working oil in the retard chambers 26, 27 and 28.

During the stop operation after the rotational phase changes to the main locking phase Pm, the internal combustion engine inertially rotates. As illustrated in FIGS. 16 and 17, the pressure of the working oil supplied from the pump 4 gradually decreases as an inertial rotational speed decreases. At this time, the pressure of the working oil in the main locking release chamber 161 decreases, and the drive shaft 186 is driven to the retreat position Le by a control of energization to the drive coil 188. Accordingly, the main locking member 160 which receives the restoring force of the main elastic member 163 is inserted into the main locking hole 162 to press the movable body 181 to the maximum open position Lomax (refer to FIG. 5). In addition, since the pressure of the working oil in the sub locking release chamber 171 decreases, the sub locking member 170 which receives the restoring force of the sub elastic member 173 is brought into contact with the rear plate 13 outside the sub locking hole 172 and the limiting groove 174 (refer to FIG. 5). As results of the inserting and the contact, the internal combustion engine completely stops in a state where the rotational phase is locked at the main locking phase Pm.

As illustrated in FIGS. 16 and 17, the operation of the internal combustion engine at the stop is changed to a starting operation based on a starting command such as an ON command of the engine switch SW or a re-starting command of the idle stop system ISS, and thus cranking is started. During the starting operation, the control circuit 80 executes steps S101 to S104 which are illustrated in FIG. 18. Specifically, an engine temperature is acquired (S101), and then it is determined which one of the acquired engine temperature and the specific temperature Ts is high (S102). In other words, the control circuit 80 determines whether the internal combustion engine is in a cold start.

When it is determined that the engine temperature is equal to or higher than the specific temperature Ts (i.e., a warm start as shown in FIG. 16), the drive shaft 186 is driven to the retreat position Le by a control of energization of drive coil 188 (S103) during the warm start. At this time, the movable body 181 at the maximum open position Lomax is not pressed by the drive shaft 186, and the movable body 181 is maintained at substantially the same position Lomax (refer to FIGS. 5 and 12). At this time, the moving position of the spool 68 is retained in the locking region R1, and the pump 4 substantially stops the supply of the working oil. Accordingly, the main locking member 160, which receives the restoring force of the main elastic member 163 in a state where a pressure loss in the main locking release chamber 161 occurs, maintains the inserting into the main locking hole 162 (refer to FIG. 5). In addition, the sub locking member 170, which receives the restoring force of the sub elastic member 173 in a state where a pressure loss in the sub locking release chamber 171 occurs, is brought into contact with the rear plate 13 outside the sub locking hole 172 and the limiting groove 174 (refer to FIG. 5). As results of the maintenance of the inserting and the contact, as illustrated in FIG. 16, the internal combustion engine undergoes a complete combustion in a state where the locking of the rotational phase is retained at the main locking phase Pm.

In contrast, when it is determined that the engine temperature is lower than the specific temperature is (i.e., a cold start as shown in FIG. 17), the drive shaft 186 is driven to the advance position Li by a control of electrification of the drive coil 188 (S104) during the cold start. At this time, as the housing rotor 11 rotates, the movable body 181 at the maximum open position Lomax is pressed by the drive shaft 186 in contact therewith, and thus the movable body 181 is driven to the blocking position Lc (refer to FIGS. 6 and 13). At this time, the moving position of the spool 68 is retained in the locking region R1, and the pump 4 substantially stops the supply of the working oil. Accordingly, in a state where a pressure loss in the main locking release chamber 161 occurs, the movable body 181 at the blocking position Lc presses the main locking member 160 against the restoring force of the main elastic member 163, and thus the main locking member 160 is removed from the main locking hole 162 (refer to FIG. 6). In addition, the sub locking member 170, which receives the restoring force of the sub elastic member 173 in a state where a pressure loss in the sub locking release chamber 171 occurs, is brought into contact with the rear plate 13 outside the sub locking hole 172 and the limiting groove 174.

During the cold start during which the locking of the rotational phase is released from the locking phases Pm and Ps by the removal and the contact, the vane rotor 14 rotates in the advance direction relative to the housing rotor 11 by an action of the negative torque. As a result, when the rotational phase advances from the main locking phase Pm, the sub locking member 170, which receives the restoring force of the sub elastic member 173 in a state where the pressure loss in the sub locking release chamber 171 occurs, enters the limiting groove 174. Accordingly, even though the vane rotor 14 rotates in the retard direction relative to the housing rotor 11 by an action of the positive torque, as illustrated in FIG. 17, the rotational phase is limited not to return to the main locking phase Pm.

The movable body 181 is pressed by the drive shaft 186, thereby releasing the locking, and the rotational phase advances from the main locking phase Pm. Thereafter, the drive shaft 186 is not always necessary to maintain at the advance position Li. In the embodiment as illustrated in FIG. 17, the drive shaft 186 is retained at the advance position Li until the internal combustion engine undergoes one rotation from cranking, and the drive shaft 186 is driven to the retreat position Le after one rotation. However, for example, the drive shaft 186 may be continuously retained at the advance position Li during the cranking.

Thereafter, when the rotational phase further advances by the action of the negative torque and changes to the sub locking position Ps, the sub locking member 170, which receives the restoring force of the sub elastic member 173 in a state where the pressure loss in the sub locking release chamber 171 occurs, is inserted into the sub locking hole 172 (refer to FIG. 7). At this time, the main locking member 160, which receives the restoring force of the main elastic member 163 in a state where the pressure loss in the main locking release chamber 161 occurs, is brought into contact with the rear plate 13 outside the main locking hole 162 (refer to FIG. 7). As results of the inserting and the contact, as illustrated in FIG. 17, the internal combustion engine undergoes a complete combustion in a state where the locking of the rotational phase is switched to the locking at the sub locking phase Ps.

(Operation Effect)

Hereinafter, operation effects of the apparatus 1 described above will be described.

In the apparatus 1, during the warm start of the internal combustion engine during which it is determined that the engine temperature is equal to or higher than the specific temperature Ts, the movable body 181, which opens or closes the main locking hole 162 by reciprocating in the main locking hole 162, is maintained at the open position Lo. As a result, since the inserting of the main locking member 160 into the main locking hole 162 is maintained at the main locking phase Pm which is reached during the starting of the internal combustion engine, the rotational phase remains locked at the main locking phase Pm. Herein, at the main locking phase Pm at which the intake valve 9 is closed at timing later than when the piston 8 reaches the bottom dead center BDC of the cylinder 7, gas in the cylinder 7 is pushed into an intake system as the piston 8 lifts up after the bottom dead center, and thus an actual compression ratio decreases (referred to as a decompression effect). Accordingly, during the warm start, for example, even though a re-start is frequently repeated by the idle stop system ISS, the locking of the rotational phase is retained at the main locking phase Pm, and occurrence of a starting failure is suppressed.

In contrast, during the cold start of the internal combustion engine during which it is determined that the engine temperature is lower than the specific temperature Ts, the movable body 181 is driven to the blocking position Lc. Since the main locking member 160 is removed from the main locking hole 162 at the main locking phase Pm which is reached during the starting of the internal combustion engine, the locking of the rotational phase is released. At this time, the vane rotor 14, which receives a variable torque from the cam shaft 2, rotates in the advance direction relative to the housing rotor 11, and thus the rotational phase changes to the sub locking phase Ps advanced more than the main locking phase Pm. As a result, the sub locking member 170 is inserted into the sub locking hole 172 and the rotational phase is locked at the sub locking phase Ps, and thus a closing timing of the intake valve becomes as quickly as possible. Accordingly, the amount of gas being pushed out of the cylinder 7 decreases, and a temperature of the gas increases together with the actual compression ratio. During the cold start after stop under a cold condition, for example, even during a start after the vehicle is soaked for a long time under an extremely cold temperature condition or even during a re-start after the vehicle temporarily stops or completely stops by the idle stop system ISS, ignitability improves and startability can be ensured.

According to the aforementioned characteristics of the apparatus 1, a start optimized for the engine temperature can be realized.

During the cold start, the drive shaft 186 outside the housing rotor 11 presses the protruding end portion 183 of the movable body 181 at the open position Lo, which protrudes to the outside of the housing rotor 11 from the main locking hole 162. As a result, not only the movable body 181 is reliably driven to the blocking position Lc so that the locking of the rotational phase can be released, but also the drive shaft 186 is prevented from interfering with a rotation of the vane rotor 14 in the housing rotor 11 relative to the housing rotor 11 so that the rotational phase can smoothly change to the sub locking phase Ps. Accordingly, a time period which it takes from cranking during which a variable torque is generated during cranking of the cold start of the internal combustion engine until when the rotational phase is locked at the sub locking phase Ps can be shortened, and thus reliability can be improved particularly in cold startability.

Furthermore, since the movable body 181 reciprocates in a direction angled relative to the axis of the rotors 11 and 14, that is, a direction in which a centrifugal force acts, an impact of the centrifugal force on the reciprocating motion becomes small. Accordingly, the movable body 181 can quickly move to the open position Lo at which the locking of the rotational phase is retained at the main locking phase Pm, or to the blocking position Lc at which the locking of the rotational phase is released. As a result, when the rotational phase is switched to a rotational phase optimized for each of the warm start and the cold start, responsiveness can be improved.

Furthermore, during the warm start, the drive shaft 186 withdraws from the rotation region Ar of the protruding end portion 183, and thus the movable body 181 is not pressed by the drive shaft 186 and can be reliably maintained at the open position Lo. In contrast, during the cold start, the drive shaft 186 supported by the stationary component of the internal combustion engine advances into the rotation region Ar of the protruding end portion 183, and thus the movable body 181 is brought into contact with the outer circumferential surface 183a of the protruding end portion 183 as the housing rotor 11 rotates. At this time, since the drive shaft 186 is brought into contact with the taper-shaped outer circumferential surface 183a of the protruding end portion 183 the diameter of which is gradually decreases toward the distal end, the movable body 181 receives a partial force from the drive shaft 186 in the direction of the movement of the movable body 181 which is parallel to the axis of the rotors 11 and 14, and the movable body 181 can be reliably pressed and driven toward the blocking position Lc. In addition, even though the columnar movable body 181 rotates around the center line of the cylindrical main locking hole 162, a contact angle of the drive shaft 186 with respect to the taper-shaped outer circumferential surface 183a is substantially constant, and thus the movable body 181 can be stably pressed toward the blocking position Lc. Accordingly, the movable body 181 can accurately move to the open position at which the locking of the rotational phase is retained at the main locking position Pm, or to the blocking position Lc at which the locking of the rotational phase is released. As a result, when the rotational phase is switched to a rotational phase optimized for each of the warm start and the cold start, reliability can be improved.

In addition, when the rotational phase of the vane rotor 14 is between the main locking phase Pm and the sub locking phase Ps, the advance angle elastic member 19 biases the vane rotor 14 in the advance direction relative to the housing rotor 11. Accordingly, during the cold start of the internal combustion engine, the vane rotor 14 receives a variable torque as well as a biasing force of the advance angle elastic member 19, and thus the vane rotor 14 can quickly change the rotational phase relative to the housing rotor 11 to the sub locking phase Ps. As a result, a time period which it takes from when a variable torque is generated during cranking of the cold start of the internal combustion engine until the rotational phase is locked at the sub locking phase Ps can be shortened, and thus reliability can be improved particularly in cold startability.

Second Embodiment

As illustrated in FIG. 19, the Second Embodiment of the present disclosure is a modification example of the First Embodiment. A driving source 2182 of the Second Embodiment can drive the drive shaft 186 toward only the advance position Li based on a control of energization of the drive coil 188. In a housing rotor 2011 of the Second Embodiment, a rear plate 2013 is integrally provided with a sliding contact surface 2130 and a parking surface 2132.

Specifically, the sliding contact surface 2130 is provided on a plate cam 2134 that protrudes in a direction parallel to the axis of the housing rotor 2011 toward the outside of the housing rotor 2011 from the rear plate 2013. The sliding contact surface 2130 is disposed to be shifted from the protruding end portion 183 in a rotational direction of the rotors 11 and 14, and the sliding contact surface is laid at least between an innermost circumferential edge and an outermost circumferential edge of the rotation region Ar. The sliding contact surface 2130 is formed to be an inclined surface that is substantially in parallel to the axis of the rotors 11 and 14 and is angled relative to a radial direction of the rotors 11 and 14 at an angle of 30° to 40°.

The parking surface 2132 is provided on the plate cam 2134 to be adjacent to the sliding contact surface 2130. The parking surface 2132 is disposed to be shifted from the protruding end portion 183 in a rotational direction of the rotors 11 and 14. The parking surface 2132 is formed in an inclined surface that is substantially in parallel to the axis of the rotors 11 and 14 and is angled relative to the radial direction of the rotors 11 and 14 at an angle of approximately 90°.

In such a configuration, when the drive coil 188 is not energized, the driving source 2182 allows movement of the drive shaft 186 by an action of an external force. At this time, in particular, when the drive shaft 186 is present at the advance position Li, as illustrated in FIG. 20, the tip portion 187 is brought into contact with the sliding contact surface 2130 as the housing rotor 2011 rotates, and thus the tip portion 187 receives a partial force F′ as an external force, which acts toward the retreat position Le. As a result, as the housing rotor 2011 continues to rotate, the drive shaft 186 is driven toward the retreat position Le in a state where the drive shaft 186 is in slide contact with the sliding contact surface 2130, and as illustrated in FIG. 21, the drive shaft 186 reaches the retreat position Le to be in contact with the parking surface 2132. As far as a control of energization of the drive coil 188 is not started, the drive shaft 186 which reaches the retreat position Le maintains a state of being parked at the retreat position Le, and is brought into slide contact with the parking surface 2132 per every rotation of the housing rotor 2011. In contrast, when the drive shaft 186 is present at the retreat position Le, and a control of electrification of the drive coil 188 is started, the drive shaft 186 is driven toward the advance position Li as far as the drive shaft 186 is not brought into contact with the sliding contact surface 2130 by the rotation of the housing rotor 2011.

In the Second Embodiment, during the normal start, the stop and the warm start, the drive coil 188 is not energized, and thus the drive shaft 186 maintains a state of being parked at the retreat position Le. In contrast, during the cold start in the Second Embodiment, energization of the drive coil 188 is controlled, and thus the drive shaft 186 is driven to the advance position Li. At this time, in particular, in the Second Embodiment, until the locking of the rotational phase is released by the drive shaft 186 that reaches the advance position Li, and the rotational phase is advanced from the main locking phase Pm, timing of starting energization to the drive coil 188 is controlled in such a manner that the drive shaft 186 is not brought into contact with the sliding contact surface 2130. In addition, in the Second Embodiment, after the rotational phase is advanced from the main locking phase Pm, timing of stopping energization of the drive coil 188 is controlled in such a manner that the drive shaft 186 can be driven toward the retreat position Le by slide contact between the drive shaft 186 and the sliding contact surface 2130.

According to the Second Embodiment described up to now, even though the driving source 2182 is not energized, the drive shaft 186 can be mechanically driven to the retreat position Le. Accordingly, the driving source 2182 can be downsized and simplified, and the rotational phase during the cold start is reliably switched, and thus reliability can be improved.

Other Embodiments

As such, a plurality of the embodiments of the present disclosure are described. However, it is not meant that the present disclosure is limited to the embodiments. Various embodiments are applicable insofar as the various embodiments do not depart from the scope of the present disclosure.

Specifically, in a First Modification Example of the First and Second Embodiments, the movable body 181 may reciprocate in a direction parallel to the radial direction of the rotors 11, 2011 and 14. In First Modification Example, for example, the main locking hole 162 can be formed to pass through the shoe ring 12 along the direction parallel to the radial direction of the rotors 11, 2011 and 14, and the main locking member 160 can also reciprocate along the direction parallel to the radial direction thereof. In the First Modification Example of the Second Embodiment, for example, the sliding contact surface 2130 is formed to be an inclined surface that is angled relative to the axis of the rotors 2011 and 14.

In a Second Modification Example of the First Embodiment, the locking members 160 and 170 may be supported by the housing rotor 11, and the limiting groove 174 and the locking holes 162 and 172 may be formed in the vane rotor 14. In the Second Modification Example, for example, the driving source 182 is built in the vane rotor 14 which is a rotation system, and the drive shaft 186 is supported by the rotor 14.

In a Third Modification Example of the First and Second Embodiments, as illustrated in a modification example of FIG. 22, the protruding end portion 183 may be provided with a flat inclined surface 183b that inclines with respect to the center line of the movable body 181, and the drive shaft 186 may be brought into contact with the inclined surface 183b as the housing rotors 11 and 2011 rotate. In a Fourth Modification Example of the First and Second Embodiments, the protruding end portion 183 may protrude to the outside of the housing rotors 11 and 2011 from the main locking hole 162 at least at the open position Lo. For example, the protruding end portion 183 may be drawn into the main locking hole 162 at the blocking position Lc.

In a Fifth Modification Example of the First and Second Embodiments, the main locking member 160 as the “sub locking member” may be inserted into the sub locking hole 172 at the sub locking phase Ps. In this case, the elements 170, 171 and 173 of the sub locking mechanism 17 are not required.

In a Sixth Modification Example of the First and Second Embodiments, for example, a member made of rubber may be adopted as the elastic members 163 and 173 in addition to metallic springs other than the coil spring. In a Seventh Modification Example of the First and Second Embodiments, an electrically driven pump may be adopted as the pump 4, and the electrically driven pump can start supplying the working oil at a complete combustion of the internal combustion engine or at any time.

In an Eighth Modification Example of the First and Second Embodiments, if the main locking phase Pm is a rotation phase at which the intake valve 9 is closed at timing later than when the piston 8 reaches the bottom dead center BDC of the cylinder 7, the main locking phase Pm may be set to be advanced more than the most retarded angle phase. In a Ninth Modification Example of the First and Second Embodiments, the sub locking phase Ps may be set to a rotational phase at which the intake vale 9 is closed at as earlier timing as possible than when the piston 8 reaches the bottom dead center BDC of the cylinder 7 of the internal combustion engine.

In a Tenth Modification Example of the First and Second Embodiments, the advance angle elastic member 19 may not be provided. In this case, the movement of the spool 68 into the locking region R1 and the inertial rotation of the internal combustion engine are performed in a reverse sequence. In an Eleventh Modification Example of the First and Second Embodiments, when the internal combustion engine is stopped based on an OFF command of the switch SW, the rotational phase is locked at the sub locking phase Ps, and then when the internal combustion engine starts based on an ON command of the switch SW, the locking of the rotational phase at the phase Ps may be realized as it is. Alternatively, in a Twelfth Modification Example of the First and Second Embodiments, when the internal combustion engine is stopped based on an idle stop command, the rotational phase is locked at the sub locking phase Ps, and then when the internal combustion engine starts based on a re-starting command, the locking of the rotational phase at the phase Ps may be realized as it is.

Claims

1. A valve timing adjustment apparatus that adjusts valve timing of an intake valve, which opens and closes a cylinder of an internal combustion engine, by a pressure of a working fluid, the valve timing adjustment apparatus comprising:

a housing rotor that rotates in connection with a crank shaft of the internal combustion engine;

a vane rotor that rotates in connection with a cam shaft of the internal combustion engine, a rotational phase of the vane rotor relative to the housing rotor being changed by receiving the pressure of the working fluid in the housing rotor;

a main locking portion that has a main locking member and a main locking hole, the main locking portion locking the rotational phase to a main locking phase, at which the intake valve is closed at timing later than when a piston in the cylinder reaches a bottom dead center of the cylinder, by inserting the main locking member into the main locking hole when the rotational phase is the main locking phase during the starting of the internal combustion engine;

a sub locking portion that has a sub locking member and a sub locking hole, the sub locking portion locking the rotational phase to a sub locking phase, which is advanced more than the main locking phase, by inserting the sub locking member into the sub locking hole when the rotational phase is changed from the main locking phase to the sub locking phase during the starting of the internal combustion engine;

a movable body that is disposed in the main locking hole to reciprocate between an open position at which the movable body opens the main locking hole and a blocking position at which the movable body blocks the main locking hole;

a determination portion that determines a warm start when a temperature of the internal combustion engine is equal to or higher than a specific temperature and a cold start when a temperature of the internal combustion engine is lower than the specific temperature; and

a driving source that maintains the movable body at the open position, at which the main locking member is inserted into the main locking hole, when the determination portion determines the warm start, and drives the movable body to the blocking position, at which the main locking member is removed from the main locking hole, when the determination portion determines the cold start.

2. The valve timing adjustment apparatus according to claim 1, wherein

the movable body has a protruding end portion that protrudes to an outside of the housing rotor from the main locking hole when the movable body is at the open position, and

the driving source has a drive shaft disposed outside the housing rotor that presses the protruding end portion at the open position toward the blocking position during the cold start.

3. The valve timing adjustment apparatus according to claim 2, wherein

the housing rotor and the vane rotor rotate around an axis,

the movable body reciprocates in a direction parallel to the axis of the housing rotor and the vane rotor,

the protruding end portion has a tapered outer circumferential surface having a diameter that decreases toward a distal end of the protruding end portion,

the drive shaft is supported by a stationary component of the internal combustion engine, and

the driving source withdraws the drive shaft from a rotation region of the protruding end portion during the warm start and advances the drive shaft into the rotation region during the cold start.

4. The valve timing adjustment apparatus according to claim 3, wherein

the housing rotor integrally has a sliding contact surface which is an inclined surface angled relative to a radial direction of the housing rotor and the vane rotor, and

the drive shaft is brought into sliding contact with the sliding contact surface and driven from an advance position inside of the rotation region to a retreat position outside of the rotation region as the housing rotor rotates.

5. The valve timing adjustment apparatus according to claim 1, wherein

the housing rotor and the vane rotor rotate around an axis, and

the movable body reciprocates in a direction parallel to the axis of the housing rotor and the vane rotor.

6. The valve timing adjustment apparatus according to claim 1, further comprising:

an advance angle elastic member that biases the vane rotor in an advance direction relative to the housing rotor when the rotational phase of the vane rotor is between the main locking phase and the sub locking phase.