VALVE LIFT ASSEMBLY FOR A CAM-IN-BLOCK ENGINE

Abstract

An engine includes a block containing multiple valves, and a camshaft defining multiple cams for rotation about a camshaft axis. A valve lift assembly is operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis. The assembly includes a follower and a follower control mechanism. The follower is disposed in contact with the cam at a contact point that defines a contact path extending along a surface of the cam as the cam rotates about the camshaft axis. The follower is moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam. The follower control mechanism is operable to control the movement of the follower within the adjustment range.

Description

TECHNICAL FIELD

The present disclosure relates to an engine having a variable valve timing mechanism. More particularly, the present disclosure relates to a valve lift assembly for a cam-in block engine.

BACKGROUND

It is known in the art to adjust the position of a follower relative to the axis of its reciprocal movement. GB607973 for example discloses a follower with a straight edge that bears slidingly on a cam. The angle of the straight edge on the cam can be manually adjusted.

Many other ways are known in the art to adjust the action of a follower with respect to a cam, for example, so as to deactivate a cylinder or alter the timing or other valve operation parameters of an internal combustion engine. Such means are often incorporated into engines of the cam-in-block type, which is to say, of the type having a camshaft located in the engine block and acting upon the valves of the engine via valve lift assemblies that reciprocate within the block. Cam-in-block engines are often used for example in large commercial vehicles and other heavy applications.

Variable valve timing (VVT) has proved to be useful in internal combustion engines for various reasons including, causing an increase in intake airflow as a function of speed, improving fuel consumption via the Miller cycle, changing exhaust temperature for after-treatment thermal management, increasing energy density to the turbocharger for improved response, facilitating an internal exhaust gas recirculation (EGR) and the like. Previously known VVT mechanisms available to do this often require significant changes to the engine, added expense or both. To that end, the incorporation of a cam follower adjustment mechanism in a cam-in-block engine typically requires extensive modifications to the engine block and other components to accommodate the adjustment mechanism, which of course must be operable while the engine is running. Such modifications can be complex and expensive, particularly where the adjustment mechanism comprises components which protrude significantly beyond the generally cylindrical envelope defined by a lift rod which reciprocates in a cylindrical hole in the engine block.

SUMMARY OF THE DISCLOSURE

In an aspect of the present disclosure, an engine includes a block, a plurality of valves, and a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis. The engine also includes multiple valve lift assemblies, each valve lift assembly being mounted in the block and operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis. Each valve lift assembly includes a follower, the follower being arranged in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; the follower being moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis. Each valve lift assembly further includes a follower control mechanism that is operable to control the movement of the follower within the adjustment range.

In another aspect of the present disclosure, a valve lift assembly is provided for a cam-in-block engine including a block; a plurality of valves; and a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis. The valve lift assembly is configured to be mounted in the block in operative association with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis. The valve lift assembly includes a follower configured to rest in contact with the cam at a contact point that defines a contact path extending along a surface of the cam as the cam rotates about the camshaft axis. The follower is moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis. The valve lift assembly further includes a follower control mechanism that is operable to control the movement of the follower within the adjustment range.

In yet another aspect of the present disclosure, a method of providing adjustable valve operation in a cam-in-block engine includes positioning a follower in contact with a cam at a contact point such that the contact point defines a contact path extending along a surface of the cam as the cam rotates about the camshaft axis. The method also includes mounting the follower for movement through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and providing a follower control mechanism that is operable to control the movement of the follower within the adjustment range.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic front cross-sectional representation of a first valve lift assembly showing a follower positioned in a first extreme position A, in accordance with an embodiment of the present disclosure;

FIG. 2 is a diagrammatic front cross-sectional representation of the first valve lift assembly from FIG. 1 showing the follower positioned in a second extreme position B;

FIG. 3 is a diagrammatic front cross-sectional representation of the first valve lift assembly showing the follower positioned in an intermediate position C disposed between extreme positions A and B shown in FIGS. 1 and 2 respectively;

FIG. 4 is a diagrammatic front cross-sectional representation of a second valve lift assembly showing first and second components with a guide element that are configured to co-operatively bring about movement of a follower, in accordance with another embodiment of the present disclosure;

FIG. 5 is a diagrammatic front cross-sectional representation of the second valve lift assembly from FIG. 4 showing the follower positioned in a first extreme position A;

FIG. 6 is a diagrammatic front cross-sectional representation of the second valve lift assembly from FIG. 4 showing the follower positioned in a second extreme position B;

FIG. 7 is a diagrammatic front cross-sectional representation of the second valve lift assembly showing the follower positioned in an intermediate position C disposed between extreme positions A and B shown in FIGS. 5 and 6 respectively;

FIG. 8 is a diagrammatic front cross-sectional representation of a third valve lift assembly showing a follower control assembly being configured to move the follower, in accordance with another embodiment of the present disclosure in which the follower is being shown located at a first extreme position A;

FIG. 9 is a diagrammatic top cross-sectional representation of the third valve lift assembly taken from FIG. 8;

FIG. 10 is a diagrammatic front cross-sectional representation of the third valve lift assembly from FIG. 8 showing the follower positioned in a second extreme position B;

FIG. 11 is a diagrammatic top cross-sectional representation of the third valve lift assembly taken from FIG. 10;

FIG. 12 is a diagrammatic front cross-sectional representation of a fourth valve lift assembly showing a follower control assembly being configured to move the follower, in accordance with yet another embodiment of the present disclosure in which the follower is being shown located at a first extreme position A;

FIG. 13 is a diagrammatic top cross-sectional representation of the fourth valve lift assembly taken from FIG. 12;

FIG. 14 is a diagrammatic front cross-sectional representation of the fourth valve lift assembly from FIG. 12 showing the follower positioned in a second extreme position B;

FIG. 15 is a diagrammatic top cross-sectional representation of the fourth valve lift assembly taken from FIG. 14;

FIG. 16 is a method of providing adjustable valve operation in a cam-in-block engine; and

FIG. 17 is an exemplary schematic of an engine employing multiple valve lift assemblies, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference numerals appearing in more than one figure indicate the same or corresponding parts in each of them. References to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.

In embodiments, a follower control mechanism may be any mechanism that is operable to control the movement of the follower within its adjustment range so as to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis. This means that at any given angular position of the cam, the exact position of the contact point along the contact path will depend on the state of the follower control mechanism. By using the follower control mechanism to adjust the position of the contact point, the valve timing of the respective individual valve controlled by the respective valve lift mechanism may be adjusted with respect to the angular position of the camshaft.

In embodiments, a follower control mechanism may include an actuator operatively associated with the follower to move the follower within the adjustment range. The actuator may be any means for imparting motion to the follower, and may comprise one component or an assembly of several components which are moveable together or relatively to one another.

The actuator may be operatively associated with the follower by any suitable mechanical connection for transmitting motion directly or indirectly between the actuator and the follower. For example, the follower may be mounted on a carrier which is moveable by the actuator, or the follower may be moveably mounted in a guide and the actuator mechanically engaged either directly or indirectly with the follower so as to move the follower relative to the guide.

The actuator may be operable hydraulically, electrically, or otherwise as known in the art. Where the actuator is a hydraulically operable actuator, the actuator may be operated by fluid pressure applied to the actuator via fluid passageways extending through the engine block and communicating with a hole in the engine block within which the valve lift assembly is arranged. Suitable seals such as sliding seals may be provided as known in the art to establish pressurised fluid communication between the relatively moveable parts.

In embodiments, a follower control mechanism may include one or more actuators which are arranged to provide a bidirectional actuating force to move the follower in opposite directions. In further embodiments, a follower control mechanism may include one or more actuators which provide a unidirectional actuating force which acts against a restoring force, for example, provided by a return spring. In each case, the actuating force may act in rotation, in a direction parallel or collinear with the lift axis, or in a direction non-parallel with the lift axis, for example, normal to the lift axis. The follower may slide along the contact path, but preferably is a roller follower to reduce wear.

Advantageously, as further described below, embodiments may allow the valve timing to be adjusted without affecting the valve lift amplitude. Further advantageously, as further described below, embodiments may allow a valve lift mechanism including a follower control mechanism to be incorporated into a generally conventional engine block, for example, within a cylindrical hole designed to receive a conventional valve lift mechanism in a generally conventional engine block, without requiring extensive modification or repositioning of other major engine components.

FIG. 1 shows a valve lift assembly 100 including a follower control mechanism 102, in accordance with an embodiment of this disclosure. The follower control mechanism 102 includes an actuator 104 that is configured to move relative to a housing 106 of the valve lift assembly 100 to impart motion to a follower 108. In this example, the follower 108 is a roller follower which rotates about an axle 110 slidably received in a guide 112, and the actuator 104 has an inclined lower surface 114 which engages the axle 110 to urge the follower 108 along the guide 112. The guide 112 may be for example a slot, which in the illustrated example is fixed in relation to the generally cylindrical housing 106 of the valve lift assembly 100, wherein the housing 106 is reciprocally movable in an engine block 116.

The actuator 104 may be operable for example hydraulically or electrically or otherwise as known in the art. In embodiments, the actuator 104 may include a mechanism of the general type used to selectively deactivate a cylinder in a cam-in-block engine. One such mechanism is known for example from U.S. Pat. No. 7,673,601 B2. Such a mechanism may be arranged for example above the actuator 104 in FIG. 1 within the generally cylindrical housing 106 of the valve lift assembly 100.

With continued reference to FIG. 1, a valve 118 is shown rotatably supported in the engine block 116 by a pin 120. The valve 118 could be resiliently biased to a flow blocking position by a spring 122 disposed between the block 116 and one end 124 of the valve 118. The valve 118 is operable to pivot about the pin 120 for communicating fluid/s e.g., air, fuel, and/or exhaust gases with a combustion chamber of the engine (not shown). Although one configuration of the valve is schematically depicted in FIG. 1, it may be noted that embodiments of the present disclosure can be applied to various other configurations of valves known to persons skilled in the art without deviating from the spirit of the present disclosure.

The block 116 is also configured to rotatably support a camshaft 126 having thereon multiple cams. One cam 128 is shown disposed on the camshaft 126 in the front cross-sectional view of FIG. 1. Moreover, the valve lift assembly 100 is mounted in the block 116. Advantageously, the valve lift assembly 100 could be received within a cylindrical hole 130 defined in the block 116. The valve lift assembly 100 is operatively associated with the cam 128 and the valve 118 to transfer motion from the cam 128 to the valve 118 by reciprocal motion of the valve lift assembly 100 along a lift axis AA′.

Further, as shown in FIG. 1, the follower 108 is arranged in contact with the cam 128 at a contact point C1 corresponding to a position A of the follower 108 within an adjustment range R as defined by the guide 112. The contact point C1 defines a contact path C2 extending along a surface 132 of the cam 128 as the cam 128 rotates about a camshaft axis CC′. In embodiments herein, the follower 108 is moveable through the adjustment range R to change the position of that contact point C1 along the contact path C2 at a given angular position of the cam 128 about the camshaft axis CC′. In embodiments of this disclosure, the follower 108 is moveable within the adjustment range R between two extreme positions as shown and indicated by ‘A’ and ‘B’ in FIGS. 1 and 2 respectively. The two extreme positions A and B define two contact point positions C1 and C3 of the follower 108 with the cam 128 as shown in FIGS. 1 and 2 respectively.

The follower control mechanism 102 is operable to control the movement of the follower 108 within the adjustment range R. In this embodiment, the actuator 104 is arranged to move the follower 108 within the adjustment range R. As shown, the actuator 104 is slidably disposed within the housing 106 of the valve lift assembly 100, and moveable in a direction P collinear or parallel with the lift axis AA′ to move the follower 108 within the adjustment range R.

The follower control mechanism 102 may further include an actuating unit 134 that is configured to communicate with the actuator 104 and therefore, bring about a movement of the follower 108 within its adjustment range R. In a first mode of operation, the actuating unit 134 may be configured to move the actuator 104 downwardly relative to the housing 106 so that the actuator 104 urges the roller 110 leftward of the lift axis AA′ and hence, move the follower 108 towards the first extreme position A within the adjustment range R shown in FIG. 1. In a second mode of operation, the actuating unit 134 may be configured to move the actuator 104 upwardly relative to the housing 106 so that the actuator 104 urges the axle 110 rightward of the lift axis AA′ and hence, move the follower 108 towards the second extreme position B within the adjustment range R shown in FIG. 2.

In embodiments herein, it is also contemplated that the follower control mechanism 102 can be arranged to provide infinite adjustment of the follower 108 within the adjustment range R. For example, as shown in FIG. 3, the actuator 104 may be configured to bias the axle 110 such that the follower 108 is disposed in an intermediate position that is located between the two extreme positions A and B shown in FIGS. 1 and 2 respectively. Advantageously, in embodiments herein, the follower control mechanism 102 may also be configured to releasably restrain the follower 108 at a selected position within the adjustment range R e.g., the intermediate position C as shown in FIG. 3.

FIGS. 4-7 show a valve lift assembly 400 including a follower control mechanism 402. The follower 444 is moveable within the adjustment range R between two extreme positions A and B which define (in any given angular position of the cam 128) two respective contact point positions C1, C3 between the follower 444 and the cam 128 as shown best in FIGS. 5 and 6 respectively. The two contact point positions C1 and C3 are arranged symmetrically about an adjustment plane BB′ containing the camshaft axis CC′. The lift axis AA′ lies within or parallel with the adjustment plane BB′. In the configuration of the valve lift assembly 400 illustrated in FIGS. 4-7, the lift axis AA′ is disposed collinearly with the adjustment plane BB′. Advantageously, since the two contact point positions C1 and C3 are spaced apart from the adjustment plane BB′ by an equal distance on either side of it, this configuration provides equal valve lift amplitude in each of the two extreme adjustment positions A and B of the follower 444. It will be appreciated of course that a similar configuration of the contact points C1 and C3 about the adjustment plane BB′ may be provided also in other embodiments which employ different actuating arrangements.

In various embodiments of this disclosure, the lift axis AA′ is shown to be generally disposed collinear to the adjustment plane BB′. However, if required, for example, to fit the valve lift assembly into a restricted space in the engine block, the lift axis AA′ could be offset slightly to one side of the camshaft axis CC′. This way, an equal lift amplitude could be achieved via the follower in both positions A and B if the positions A and B of the follower are arranged symmetrically on either side of the adjustment plane BB′ while the adjustment plane BB′ contains the camshaft axis CC′.

The follower control mechanism 402 includes a first component configured as an actuator 404 which is operatively associated with the follower 444 and operable to move the follower 444 to a selected position within the adjustment range R, and a detent actuator mechanism 410 operable to releasably restrain the follower 444 in a selected position within the adjustment range R. In the illustrated example, both the actuator 404 and the detent actuator mechanism 410 are operable by fluid pressure, and it will be appreciated that the follower 444 may also be releasably restrained in any desired position within its adjustment range R by controlling the fluid pressure selectively applied to the actuator 404 via fluid passageways 426 and 428 in the engine block 448 by an actuating unit 424 which conveniently is arranged outside the engine block 448.

The follower control mechanism 402 also includes a second component 406 defining a bore, with the actuator 404 being configured as a piston which is slidingly received in the bore. The actuator 404 is extended to form a carrier on which the follower 444 is rotatably mounted via an axle or roller 408 which functions as a guide element, while the second component 406 is embodied as the housing 452 of the valve lift assembly 400 to reciprocate in the block 448. The actuator 404 is moveable relative to the second component 406 for bringing about movement of the follower 444 within the adjustment range R.

The detent actuator mechanism 410 includes a detent 412 that is moveable by the detent actuator mechanism 410 between an engaged position in which the detent 412 is arranged to inhibit relative movement between the first and second components 404, 406 to restrain the follower 444 in a selected position within the adjustment range R, and a disengaged position in which the detent 412 is arranged to permit relative movement between the first and second components 404, 406 to permit the follower 444 to move away from the selected position. It will be appreciated of course that in alternative embodiments a detent actuator mechanism may comprise relatively moveable first and second components which need not comprise an actuator.

In the example of the valve lift assembly 400 shown in FIGS. 4-7, the detent 412 may be embodied in the form of a pair of mutually opposed locking pins collectively denoted by numeral 414. The pair of mutually opposed locking pins 414 are outwardly biased into a respective one of the pair of diametrically opposed set of holes 416/418 defined in the housing 452 of the valve lift assembly 400 by a compression spring 446.

As shown in FIG. 4, the roller 408 associated with the follower 444 is slidably engaged with first and second, mutually inclined guide surfaces 420, 422 of the follower control mechanism 402. In this example, the first guide surface 420 comprises the opposed sides of a slot formed in the second component 406 i.e., the housing 452 of the valve lift assembly 400, and the second guide surface 422 comprises the opposed sides of another slot formed in the extended carrier portion of the actuator 404.

The second component 406 is slidably disposed within a cylindrical hole 450 defined by an engine block 448 and positioned adjacent to a pair of fluid channels i.e., the first and second fluid channels 426, 428 defined in the block 448. Moreover, the second component 406 also defines a pair of annular recesses i.e., a first recess 430 and a second recess 432 sealingly separated by a flange 434 that is disposed on an outer surface 436 of the housing 452 and located at a position partway along a length L of the second component 406. Additionally, as shown, the second component 406 may define an oil passage 438 disposed in communication with the first recess 430 and configured to communicate pressurized fluid received at the first recess 430 from the first channel 426 to the actuator 404. As such, the first channel 426 is disposed in communication with the oil passage 438 and the set of diametrically opposed holes 416 via the first recess 430. Likewise, the second channel 428 is disposed in fluid communication with the set of diametrically opposed holes 418 via the second recess 432.

In this example, the follower control mechanism 402 includes one actuator 404 for moving the follower through its adjustment range, although alternative embodiments could include two or more actuators for example acting in opposed directions.

A manner of working of the follower control mechanism 402 shown in FIGS. 4-7 will now be described. It is assumed that the locking pins 414 of the detent actuator mechanism 410 are initially located in the set of diametrically opposed holes 416 corresponding to the follower 444 being located in position A as shown in FIG. 5. In order to move the follower 444 into position B, pressurized fluid from the actuating unit 424 may be supplied to the first channel 426 for communicating with the actuator 404 via the first recess 430 and the oil passage 438. Pressurized fluid supplied via the first channel 426 acts against the resiliently biased locking pins 414 located in the set of diametrically opposed holes 416 to compress the compression spring 446. The pressurized fluid also urges the actuator 404 to move downwardly relative to the second component 406 with a resultant co-operative movement of the first and second guide surfaces 420, 422. The axle 408 is urged slidingly along both of the first and second guide surfaces 420, 422 as their point of intersection moves, shifting the follower 444 from position A to position B shown in FIG. 6.

If the locking pins 414 are currently disposed in the set of diametrically opposed holes 418 corresponding to the follower 444 being disposed in position B as shown in FIG. 6 and it is desired to move the follower 444 from position B to position A shown in FIG. 5, pressurized fluid from the actuating unit 424 may be supplied through the second channel 428 to the second recess 432 for communicating with the locking pins 414 located in the set of diametrically opposed holes 418. Fluid pressure applied via the second channel 428 acts against the resiliently biased locking pins 414 located in the set of diametrically opposed holes 418 to compress the compression spring 446 so that the pins 414 retract from their extended positions permitting an upward motion of the first component 404 relative to the second component 406.

In the illustrated embodiment, the actuator 404 is moveable by the actuating unit 424 in one direction against a resilient restoring force of a return spring 442 disposed within the second component 406 i.e., the housing 452 of the valve lift assembly 400, the return spring 442 also being disposed in abutment with the actuator 404. As best shown in FIGS. 4, 5, and 7, the return spring 442 may be embodied in the form of a compression spring which opposes the movement of the actuator 404 in the direction Q. Although it is disclosed herein that the restoring force is provided by a compression spring located within the housing 452 of the valve lift assembly 400, persons skilled in the art will acknowledge by various other structures could be used to provide the restoring force to the movement of the actuator 404 in the direction Q, such structures being located inside or outside the housing 452 of the valve lift assembly 400.

Upon compression of the spring 446 by the fluid pressure from the first channel 426 of the block 448 and subsequently, the first and second components 404, 406 becoming independently moveable in relation to one another, the actuating unit 424 can continue to supply fluid into the first channel 426 to urge the actuator 404 to move along the lift axis AA′ in the direction Q shown in FIG. 6, against the resilient restoring force of the return spring 442. A resultant co-operative movement of the first and second guide surfaces 420, 422 urges the roller 408 and hence the follower 444 from position B to position A shown in FIG. 5.

In a development, fluid pressure from the actuating unit 424 may be controlled relative to the restoring force of the return spring 442 to provide infinite adjustment of the follower 444 to any selected point between positions A and B within the adjustment range R, and by closing the fluid passageway to prevent displacement of fluid from the bore in which the actuator 404 reciprocates, to releasably restrain the follower 444 against the pressure applied by the cam 128 at any selected position within the adjustment range R.

In alternative embodiments, the follower control mechanism 402 may be adapted so that fluid pressure may be applied to the oppositely directed end faces of the actuator 404 via two fluid passageways, whereby oppositely directed fluid pressure may be used to move the actuator 404 to any desired position and, by closing the fluid outlet from the respective ends of the bore in which the actuator 404 is received, also to restrain it in that position.

In yet further embodiments (not shown), incremental movement of the follower 444 between a plurality of discrete positions within the adjustment range R may be provided by arranging an actuator (such as a piston moveable by fluid pressure applied to one or both of its opposite end surfaces) to move along a path between a plurality of discrete detent positions, each detent position defined by the engagement of a detent with a corresponding recess. For example, a plurality of detents may be arranged in a housing to engage with one or more recesses of the actuator 404, or alternatively in the actuator 404 to engage with one or more recesses in a housing 452.

Alternatively, a single detent could be arranged in the actuator 404 or in the housing 452 to engage in a plurality of recesses in the other respective part. The detent may be resiliently biased into engagement with a corresponding recess. In such embodiments, when fluid pressure applied to the actuator 404 overcomes the resilient bias force of the detent engaged in a respective recess, the detent is forced out of engagement allowing movement of the actuator 404. Movement of the actuator 404 momentarily relieves the fluid pressure, so that when the actuator 404 reaches the next position defined by engagement of the detent with another recess, the detent engages the respective recess to restrain the actuator 404 in the new position. Increasing the fluid pressure again would cause another incremental movement to the next position defined by the next detent engagement in a similar way. In this way a plurality of discrete follower positions, each defined by the engagement of one or more detents in one or more recesses, can be achieved even when fluid pressure is less precisely controlled.

In the examples illustrated in FIGS. 8-15, the follower control mechanism 802 includes a follower 804 having a roller 806 and a carrier 808. The roller 806 is being mounted for rotation on the carrier 808 which is moveable by an actuating unit 810. In the examples of FIGS. 8-15, the actuating unit 810 could be configured to embody any type of device that is configured for moving the carrier 808 and such device could be located inside the housing 816 of the valve lift assembly 800, or outside the housing 816 of the valve lift assembly 800 as shown in FIGS. 8-11 and 12-15.

The movement of the carrier 808 within the housing 816 of the valve lift assembly 800 in consequence to which the follower 804 moves axially along a guide 812 in FIGS. 8-11 or pivotally about an axle 814 in FIGS. 12-15 is reflective of the pressurized fluid from the actuating unit 810 for executing movement of the carrier 808 in a direction non-parallel with the lift axis AA′, for example, in a direction S shown in FIGS. 8 and 10 respectively or in a direction T shown in FIGS. 12 and 14 respectively. Moreover, as disclosed earlier herein, it may be noted that the actuating unit 810 could be operated electrically or hydraulically or by any other means known to one skilled in the art for bringing about the non-parallel movement of the carrier 808 and the roller 806 with respect to the lift axis AA′ of the valve lift assembly 800.

In the embodiment illustrated in FIGS. 8-11, the carrier 808 could be slidably supported by a housing 816 of the valve lift assembly 800 and hence, moved slidably within the housing 816 of the valve lift assembly 800 by fluid pressure from the actuating unit 810 acting on a pair of pistons 828, 830 operatively coupled to the carrier 808. With regards to the embodiment illustrated in FIGS. 12-15, the carrier 808 may be embodied in the form of an arm 818 pivotably mounted on an axle 814. Moreover, in an embodiment, the arm 818 of the carrier 808 is configured to generally extend in a collinear or parallel relation with the lift axis AA′ of the follower 804 as it transitions between the positions A and B shown in FIGS. 12 and 14 respectively.

In the embodiments of FIGS. 8-11 and FIGS. 12-15, bi-directional movement of the carrier 808 with respect to the housing 816 of the valve lift assembly 800 may be accomplished by communicating pressurized fluid from the actuating unit 810 selectively and independently through one or both of a pair of mutually opposing fluid channels i.e., a first channel 822 and a second channel 824 located within the engine block 826 so that the pressurized fluid can act upon the pair of pistons 828, 830 operatively coupled to the carrier 808 for bringing about movement of the carrier 808. In this specification, it may be noted that the pistons 828 and 830 can together be regarded as an actuator capable of bringing about movement of the roller 806 within its adjustment range R.

The hydraulic actuating unit 810 may be controllable to selectively route pressurized fluid including, but not limited to, oil, hydraulic fluid etc. through the first channel 822 for entering the housing 816 of the valve lift assembly 800, and actuating the piston 830 for moving the carrier 808 leftward and consequently biasing the roller 806 into position A shown in the respective views of FIGS. 8 and 9. Alternatively, the actuating unit 810 may be configured to route the pressurized fluid through the second channel 824 to enter the housing 816, move the carrier 808 rightward and bias the roller 806 into position B shown in the respective views of FIGS. 10 and 11.

Similarly, with regards to the valve lift assembly 800 shown in FIGS. 12-15, the actuating unit 810 may be configured to route pressurized fluid through the first channel 822 to enter the housing 816 of the valve lift assembly 800, and actuate the piston 830 (shown in FIG. 13) for pivoting the arm 818 clockwise about the axle 814 and consequently biasing the roller 806 into position A shown in the respective views of FIGS. 12 and 13. Alternatively, the actuating unit 810 may be configured to route pressurized fluid through the second channel 824 to enter the housing 816, and actuate the piston 828 for pivoting the arm 818 counter-clockwise about the axle 814, and consequently biasing the roller 806 into position B shown in FIGS. 14 and 15. Therefore, depending on a desired position of the roller 806 i.e., position A or position B of the roller 806, the actuating unit 810 can be configured to route pressurized fluid into either the first channel 822 or the second channel 824 defined in the block 826.

Other methods and structures could be implemented for moving a carrier on which a roller follower is rotatably mounted, such as, but not limited to, the carrier 808 of FIGS. 8-11 or the arm 818 of FIGS. 12-15, relative to, for example, a housing of the valve lift assembly. For example, the carrier could be moveable by an actuating unit 810 in one direction against a resilient restoring force. The resilient restoring force could be provided using any means known in the art e.g., a spring that may be located within or outside of a housing of the valve lift assembly and associated with the carrier for operatively urging the carrier and hence, biasing the roller follower to one of its extreme positions, or to an intermediate position between its extreme positions. The one direction in which the resilient restoring force may oppose the movement of the carrier could include for example either of the leftward or rightward directions of the carrier 808 and the roller 806 in the case of the valve lift assembly 800 shown in FIGS. 8-11 and likewise, either of the clockwise or counter-clockwise directions of the arm 818 and the roller 806 about the axle 814 in the case of the valve lift assembly 800 shown in FIGS. 12-15.

In embodiments as disclosed herein, the follower control mechanism may also be configured to advantageously provide infinite adjustment of the follower within the adjustment range R. Also, the follower control mechanism could, additionally or optionally, be arranged to releasably restrain the follower at a selected position within the adjustment range R. In an example, when the exemplary hydraulically operated actuating unit 810 is used with the follower control mechanism 802 of FIGS. 8-11, pressurized fluid can be routed from the actuating unit 810 simultaneously through both the first and second channels 822, 824 such that the forces of the pressurized fluid from each of the fluid channels i.e., the first channel 822 and the second channel 824 counterbalance each other, with or without the presence of a resilient restoring force brought about by suitable structures e.g., a spring forming part of the follower control mechanism 802, and fluidly maintain the carrier 808 at any position partway between the extreme positions A and B of the follower 804 as shown in FIGS. 8-9 and FIGS. 10-11 respectively. The follower control mechanism 802 may also be arranged to releasably restrain the follower 804 at a selected position within the adjustment range R for example, at position A shown in FIGS. 8-9, position B shown in FIGS. 10-11, or at an intermediate position (not shown) that is located between positions A and B.

A similar arrangement could be applied to the valve lift assembly 800 of FIGS. 12-15 for facilitating infinite adjustment of the follower 804 within its adjustment range R and/or to releasably restrain the follower 804 at a selected position within its adjustment range R for example, at position A shown in FIGS. 12-13, position B shown in FIGS. 14-15, or at an intermediate position that is located between positions A and B.

In certain above described embodiments, the follower control mechanism is arranged to move the follower to a selected position within the adjustment range and to releasably restrain the follower in the selected position.

In alternative embodiments it is possible for the follower control mechanism to constrain or lock but not to accomplish the movement of the follower within the adjustment range. For example, a resilient bias means may be arranged to return the follower to a rest position within the adjustment range, and the cam may be arranged to move the follower within the adjustment range against the action of the resilient bias means to a displaced position determined by the direction of rotation of the cam, with the follower control mechanism thereafter locking the follower in the displaced position. The follower control mechanism may then unlock the follower to allow it to return it to the rest position, for example, when the follower is near the minimum diameter region of the cam and hence relieved from valve spring pressure. The follower control mechanism may then lock the follower in the rest position until it is desired to move it again to the displaced position.

In yet further embodiments, an actuator may be provided within or outside the engine block for moving the follower within the adjustment range, with the follower control mechanism incorporated into the valve lift assembly merely acting to lock the follower in the selected position. In yet further embodiments, the follower control mechanism may accomplish the movement of the follower within the adjustment range, with a separate locking mechanism within or outside the engine block being arranged to lock the follower in the position to which it has been moved by the follower control mechanism.

Aspects of the present disclosure are also directed to a method 1600 of providing adjustable valve operation in a cam-in-block engine as shown in FIG. 16. At step 1602, the method 1600 includes mounting each follower for movement through an adjustment range R to change the position of the contact point C1 along the contact path C2 at a given angular position of the cam 128 about the camshaft axis CC′. At step 1604, the method 1600 also includes providing a follower control mechanism e.g., follower control mechanism 102/402/802 in each valve lift assembly e.g., valve lift assembly 100/400/800, the follower control mechanism being operable to control the movement of the follower 108/444/804 within the adjustment range R.

Also, as shown in FIG. 17, when a multi-cylinder engine 1700 having multiple intake valves 1702 and multiple exhaust valves 1704 each of which are operatively associated with corresponding ones of multiple combustion chambers 1710, a first group of valve lift assemblies 1706 may be operatively associated with the intake valves 1702 while a second group of valve lift assemblies 1708 may be operatively associated with the exhaust valves 1704. In such case, a control system 1710 may be additionally provided for independently controlling each valve lift assembly 1706, 1708 present in a respective one of the first and second groups 1706, 1708.

Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, associated, coupled, engaged, arranged, connected and the like) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.

Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “primary”, “secondary” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.

It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims.

INDUSTRIAL APPLICABILITY

Embodiments of the follower control mechanism may have a relatively compact configuration with its components being confined generally within the typically cylindrical envelope defined by each lift rod which reciprocates in a cylindrical hole in the engine block, so that the engine block does not have to be extensively redesigned to accommodate the mechanism. This makes it possible to incorporate embodiments of the mechanism into an otherwise conventional engine block of a cam-in-block engine to provide adjustment of the valve operation parameters, particularly the valve timing, without the complexity and expense associated with the incorporation of many prior art mechanisms with comparable functionality.

Further advantageously, embodiments of the follower control mechanism may be incorporated into a cam-in-block engine to provide valve timing adjustment substantially without affecting valve lift amplitude. With use of embodiments disclosed herein, an adjustment to the timing of one or more valve can be made while the respective valves of the engine remain in an operative state i.e., when the engine would be running thereby obviating the need to turn off the engine during the adjustment procedure. Further, the adjustment in the timing of each valve may be controlled, continuously or in an intermittent manner, by a control system. The control system may be configured to adjust the timing of each valve based on various factors including, inter alia, one or more sensed parameters of the engine and/or other systems associated with the engine including, but not limited to, an after-treatment thermal management system, a turbocharger, an exhaust gas recirculation (EGR) system or any other device that is typically known to be associated with engines.

Furthermore, by using embodiments of this disclosure in an engine block having an intake valve and an exhaust valve e.g., in a single cylinder engine, the timing of each valve i.e., the intake valve or the exhaust valve can be adjusted independently of one another even if both the valves are mounted on the same camshaft. Similarly, in the case of multi-cylinder engines, with use of embodiments disclosed herein, a timing of each valve in the multi-cylinder engine can be adjusted independently of other valves present in the multi-cylinder engine.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, methods and processes without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

1. An engine including:

a block;

a plurality of valves;

a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis; and

a plurality of valve lift assemblies, each valve lift assembly being mounted in the block and operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis; each valve lift assembly including: a follower, the follower being arranged in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; the follower being moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and a follower control mechanism operable to control the movement of the follower within the adjustment range.

2. An engine according to claim 1, wherein the follower is moveable within the adjustment range between two extreme positions defining two contact point positions arranged symmetrically about an adjustment plane containing the camshaft axis, the lift axis lying within or parallel with the adjustment plane.

3. An engine according to claim 1, wherein the follower control mechanism includes an actuator arranged to move the follower within the adjustment range.

4. An engine according to claim 3, wherein the actuator is moveable in a direction parallel or collinear with the lift axis to move the follower within the adjustment range.

5. An engine according to claim 3, wherein the actuator is moveable in a direction nonparallel with the lift axis to move the follower within the adjustment range.

6. An engine according to claim 3, wherein the follower includes a guide element slidably engaged with first and second, mutually inclined guide surfaces of the follower control mechanism, the actuator being operable to move the first guide surface relative to the second guide surface.

7. An engine according to claim 3, wherein the follower includes a roller and a carrier, the roller being mounted for rotation on the carrier, the carrier being moveable by the actuator.

8. An engine according to claim 7, wherein the carrier comprises an arm pivotably mounted on an axle and extending in collinear or parallel relation with the lift axis.

9. An engine according to claim 1, wherein the follower control mechanism is arranged to provide infinite adjustment of the follower within the adjustment range.

10. An engine according to claim 1, wherein the follower control mechanism is arranged to releasably restrain the follower at a selected position within the adjustment range.

11. An engine according to claim 1, wherein the follower control mechanism is arranged to move the follower to a selected position within the adjustment range and to releasably restrain the follower in the selected position.

12. An engine according to claim 1, wherein the follower control mechanism includes:

first and second components, the first component being operatively associated with the follower and moveable relative to the second component by movement of the follower within the adjustment range; and

at least one detent actuator mechanism, the detent actuator mechanism including a detent, the detent being moveable by the detent actuator mechanism between an engaged position in which the detent is arranged to inhibit relative movement between the first and second components to restrain the follower in a selected position within the adjustment range, and a disengaged position in which the detent is arranged to permit relative movement between the first and second components to permit the follower to move away from the selected position.

13. An engine according to claim 12, wherein the detent actuator mechanism is operable by fluid pressure to move the detent, and the block includes a plurality of fluid channels, each channel fluidly communicating with a respective detent actuator mechanism to conduct fluid pressure to the detent actuator mechanism.

14. An engine according to claim 1, wherein the follower control mechanism includes an actuator mechanism, the actuator mechanism including at least one actuator operatively associated with the follower and moveable by fluid pressure to move the follower within the adjustment range, and the block includes a plurality of fluid channels, each channel fluidly communicating with a respective actuator mechanism to conduct fluid pressure to the actuator mechanism.

15. An engine according to claim 14, wherein the actuator is moveable by fluid pressure in one direction against a resilient restoring force.

16. An engine according to claim 14, wherein the actuator is reciprocally moveable by fluid pressure in two opposite directions, and the actuator mechanism is provided with two said fluid channels to apply fluid pressure in the two opposite directions.

17. An engine according to claim 1, wherein each valve lift assembly is received in a cylindrical hole in the block.

18. A valve lift assembly for a cam-in-block engine, the engine including:

a block;

a plurality of valves; and

a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis;

the valve lift assembly being configured to be mounted in the block in operative association with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis, and including:

a follower configured to rest in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis; the follower being moveable through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and

a follower control mechanism operable to control the movement of the follower within the adjustment range.

19. A method of providing adjustable valve operation in a cam-in-block engine, the engine including:

a block;

a plurality of valves;

a camshaft defining a plurality of cams and mounted in the block for rotation about a camshaft axis; and

a plurality of valve lift assemblies, each valve lift assembly being mounted in the block and operatively associated with a respective one of the cams and a respective one of the valves to transfer motion from the cam to the valve by reciprocal motion of the valve lift assembly along a lift axis; each valve lift assembly including: a follower, the follower being arranged in contact with the cam at a contact point, the contact point defining a contact path extending along a surface of the cam as the cam rotates about the camshaft axis;

the method comprising:

mounting each follower for movement through an adjustment range to change the position of the contact point along the contact path at a given angular position of the cam about the camshaft axis; and

providing, in each valve lift assembly, a follower control mechanism operable to control the movement of the follower within the adjustment range.

20. A method according to claim 19, wherein the valves include intake valves and exhaust valves, and a first group of valve lift assemblies are operatively associated with the intake valves and a second group of valve lift assemblies are operatively associated with the exhaust valves, and a control system is provided for independently controlling the valve lift assemblies of the first and second groups.