OIL SUCTION DEVICE OF VEHICLE

Abstract

An oil suction device of a vehicle has a mechanical oil pump and includes an air suction unit. The air suction unit includes a first communication passage, a second communication passage, and an opening and closing mechanism. The first communication passage communicates with an atmosphere side. The second communication passage communicates with a suction unit of the oil pump. The opening and closing mechanism is capable of switching between opening and closing of communication between the first communication passage and the second communication passage. When an oil suction pressure of the oil pump becomes a negative pressure lower than or equal to a predetermined pressure, the opening and closing mechanism is opened to cause air sucked through the air suction unit to be mixed into oil which is sucked from an oil reservoir through a suction pipe.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. $119 to Japanese Patent Application No. 2013-116637, filed Jun. 3, 2013, entitled “Oil Suction Device of Vehicle.” The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND

1. Field

The present disclosure relates to an oil suction device of a vehicle.

2. Description of the Related Art

Conventional oil pumps used for transfer of lubrication oil for gears and rotation shafts or the like and for cooling oil (lubricating oil and hydraulic oil) in a transmission mounted on a vehicle include a mechanical oil pump (gear pump) which is driven by rotation transmitted from a driving source of a vehicle such as an engine. In designing this type of oil pump, for setting necessary flow rate, a safety factor is incorporated based on the past record and experience values so as to ensure a necessary oil flow rate in a rotation region with a rotation rate lower than a predetermined rotation rate. For this reason, in a high rotation region with a rotation rate exceeding the predetermined rotation rate, oil is sucked with a flow rate more than necessary. Thus, in such a mechanical oil pump, wasteful driving torque (pump driving force) occurs in a high rotation region with a rotation rate exceeding the predetermined rotation rate, and thus the driving torque causes a loss to a driving source such as an engine.

For this problem, a mechanism that changes a flow rate or a mechanism that reduces a pump rotation rate is generally adopted as a mechanism for reducing the driving torque of a mechanical oil pump. As a mechanism that changes a flow rate, a mechanism (variable flow pump with a relief circuit) using a combination of a hydraulic pressure sensitive spool valve and a relief circuit has been proposed, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 7-233787. In addition, as a mechanism that controls a pump rotation rate, a mechanism to reduce a pump rotation rate using a planetary gear has been proposed, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-207357.

SUMMARY

According to one aspect of the present invention, an oil suction device of a vehicle has a mechanical oil pump which is driven by rotation transmitted from a driving source of the vehicle and configured to suck and pump oil in an oil reservoir to the oil pump. The oil suction device includes an air suction unit. The air suction unit is provided in a suction section in which oil in the oil reservoir is sucked by a suction unit of the oil pump. The air suction unit includes a first communication passage, a second communication passage, and an opening and closing mechanism. The first communication passage communicates with an atmosphere side. The second communication passage communicates with the suction unit of the oil pump. The opening and closing mechanism is capable of switching between opening and closing of communication between the first communication passage and the second communication passage. When an oil suction pressure of the oil pump becomes a negative pressure lower than or equal to a predetermined pressure, the opening and closing mechanism is opened to cause air sucked through the air suction unit to be mixed into oil which is sucked from the oil reservoir through a suction pipe.

According to another aspect of the present invention, an oil suction device of a vehicle includes a mechanical oil pump, a first conduit, a second conduit, and an air suction device. The mechanical oil pump is to be driven by a driving source of the vehicle and has a suction portion. The first conduit is connected to the suction portion of the mechanical oil pump. The second conduit is connected to an oil reservoir. The air suction device includes a first communication passage, a second communication passage, and an opening and closing mechanism. The first communication passage communicates with an atmosphere side. The second communication passage communicates with the first conduit and the second conduit. The opening and closing mechanism is configured to connect or disconnect the first communication passage and the second communication passage. The opening and closing mechanism connects the first communication passage and the second communication passage in a case in which an oil suction pressure in the oil pump becomes a negative pressure lower than or equal to a predetermined pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 is a schematic diagram illustrating an oil suction device according to an embodiment of the present disclosure.

FIGS. 2A and 2B illustrate an oil pump; FIG. 2A is a view illustrating the entire configuration of the oil pump; and FIG. 2B is a cross-sectional view of an air suction valve taken along line IIB-IIB.

FIGS. 3A and 3B are each a cross-sectional view for illustrating the operation of the air suction valve.

FIG. 4 is a graph illustrating a relationship between oil pump rotation rate and pump suction pressure.

FIG. 5 is a graph illustrating a relationship between oil pump rotation rate and pump torque.

FIG. 6 is a graph illustrating a relationship between oil pump rotation rate and pump flow rate.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating an oil suction device according to an embodiment of the present disclosure. FIGS. 2A and 2B illustrate an oil pump; FIG. 2A is a view illustrating the entire configuration of the oil pump; and FIG. 2B is a cross-sectional view of an air suction valve taken along line IIB-IIB. As illustrated in FIG. 1, an oil suction device 1 includes a mechanical oil pump 10 which is driven by rotation transmitted from an engine (not illustrated) serving as a driving source of a vehicle, a suction pipe 30 which is connected to a suction end 10a of the oil pump to suck oil in an oil bath (oil reservoir) 2, and a discharge pipe 60 connected to a discharge end 10b of the oil pump.

The oil pump 10 is used for lubrication of mechanical structure such as gears and for transfer of hydraulic fluid (oil) for cooling in a transmission for a vehicle. The oil pump 10 is a mechanical oil pump which is driven by rotation transmitted from a crankshaft (not illustrated) that rotates by the driving force of the engine. The oil pump 10 includes a pump unit 15 for pumping oil, a suction port (suction unit) 11 for sucking oil through the suction pipe 30 to the pump unit 15, and a discharge port 13 for discharging oil from the pump unit 15 to the discharge pipe 60. The pump unit 15 is a positive displacement trochoid pump that includes an outer rotor 16 rotatably supported in a casing 12, and an inner rotor 17 rotatably supported inside the outer rotor 16. In the oil pump 10, the amount of oil pumped by the pump unit 15 is increased or decreased according to an increase or decrease in the rotation transmitted from the engine.

The oil pump 10 of the present embodiment includes an air suction valve (air suction unit) 20 provided between an atmosphere side 100 and the suction port 11. The air suction valve 20 includes a first communication passage (atmospheric opening) 21 that communicates with the atmosphere side 100, a second communication passage 22 that communicates with the suction port 11, and a valve mechanism (open/close mechanism) 23 that allows communication between the first communication passage 21 and the second communication passages 22 when the suction pressure of the oil pump 10 becomes a negative pressure lower than or equal to a predetermined pressure (prespecified pressure). The valve mechanism 23 has a housing portion 24 formed between the first communication passage 21 and the second communication passage 22, a spherical valve element 25 housed in the housing portion 24, and a coil spring (urging unit) 26 that urges the valve element 25. The valve element 25 is movable between a closed position and an open position in the housing unit 24, the closed position at which the valve element 25 is seated on a valve seat 27 which is formed in the periphery of the first communication passage 21, the open position being spaced away from the valve seat 27. The coil spring 26 urges the valve element 25 toward the closed position at which the valve element 25 is seated on the valve seat 27. When the oil suction pressure of the oil pump 10 becomes a negative pressure lower than or equal to a predetermined pressure, the valve element 25 moves against the urging force of the coil spring 26 from the closed position to the open position.

FIGS. 3A and 3B are each a cross-sectional view for illustrating the operation of the air suction valve 20. In a state where the oil suction pressure of the oil pump 10 is higher than a predetermined pressure, the resultant force of the urging force of the coil spring 26 applied to the valve element 25 and the force applied from the hydraulic oil of the suction port 11 is greater than the force applied from the atmosphere side 100 through the first communication passage 21. Therefore, the valve element 25 seals between the first communication passage 21 and the second communication passages 22 with the valve element 25 seated on the valve seat 27 due to the urging force of the coil spring 26. When the oil suction pressure of the oil pump 10 is in a negative pressure state lower than or equal to the predetermined pressure, the force applied from the atmosphere side 100 through the first communication passage 21 is greater than the resultant force of the urging force of the coil spring 26 applied to the valve element 25 and the force applied from the hydraulic oil of the suction port 11. Consequently, the valve element 25 moves away from the valve seat 27 against the urging force of the coil spring 26, thereby allowing communication between the first communication passage 21 and the second communication passages 22. In this manner, a first suction operational state and a second suction operational state are switched therebetween according to a suction pressure of the oil in an oil bath 2 caused by the oil pump 10, the first suction operational state allowing only the oil in the oil bath 2 to be sucked through the suction pipe 30, the second suction operational state allowing the oil in the oil bath 2 to be sucked through the suction pipe 30 and allowing air to be sucked through the air suction valve 20.

In the first suction operational state, only oil is sucked through the suction pipe 30 by the operation of the oil pump 10 and air is not sucked through the air suction valve 20. In the first suction operational state, air is not sucked into the oil pump 10, and thereby a linear increase in oil flow rate is obtained, the linear increase being approximately proportional to the rotation rate of the oil pump 10. In the second suction operational state, oil is sucked through the suction pipe 30 and air is sucked through the air suction valve 20 by the operation of the oil pump 10. Because the air sucked through the air suction valve 20 is mixed into the oil pump 10, an increase in pump negative pressure and pump driving force is maintained to be low (in contrast to a state in which no air is mixed). That is, the oil suction device 1 in the present embodiment is capable of limiting the amount of oil suction and reducing the hydraulic pressure power of the oil pump 10 by mixing air into the oil which is sucked into the oil pump 10. In this manner, by mixing the air sucked through the air suction valve 20 into the oil which is sucked through the oil bath 2, the amount of oil suction in relation to the rotation rate of the oil pump 10, particularly, in a high rotation region may be reduced to a lower level.

FIGS. 4 to 6 are graphs for illustrating performance comparison between the oil suction device 1 in the present embodiment and an oil suction device in a conventional configuration. FIG. 4 is a graph illustrating a relationship between the rotation rate (input rotation rate) and pump suction pressure of the oil pump 10; FIG. 5 is a graph illustrating a relationship between the rotation rate and pump torque of the oil pump 10; and FIG. 6 is a graph illustrating a relationship between the rotation rate and pump flow rate of the oil pump 10. In FIGS. 5 and 6, the graph for the oil suction device 1 in a conventional configuration is indicated by a solid line, and the graph for the oil suction device in the present embodiment is indicated by a dotted line. The oil suction device in a conventional configuration herein does not include the air suction valve 20 according to the present embodiment.

In the oil pump 10 in the present embodiment, as illustrated in FIG. 4, in the region where pump rotation rate N is lower than a predetermined rotation rate N1, pump suction pressure P is higher than a predetermined pressure (prespecified negative pressure) P1 (P>P1), and in the region where the pump rotation rate N is higher than or equal to the predetermined rotation rate N1, the pump suction pressure P is lower than or equal to the predetermined pressure (prespecified negative pressure) P1 (P≦P1). Thus, in the region where the pump rotation rate N is lower than the predetermined rotation rate N1, the oil pump 10 is in the first suction operational state in which only oil is sucked through the suction pipe 30, and in the region where the pump rotation rate N is higher than or equal to the predetermined rotation rate N1, the oil pump 10 is in the second suction operational state (air mixed state) in which air sucked through the air suction valve 20 is mixed into the oil which is sucked through the suction pipe 30. Thereby, as illustrated in the graph of FIG. 6, in contrast to the oil suction device in a conventional configuration, an increase in the flow rate of the sucked oil may be reduced (rate of increase may be reduced) in a high rotation region with the predetermined rotation rate N1 or higher. Therefore, as illustrated in FIG. 5, a pump torque reduction effect is achieved. Consequently, pumping loss and transmission loss may be reduced.

As described above, in the oil suction device 1 in the present embodiment, equipped with the mechanical oil pump 10 which is driven by rotation transmitted from a driving source of a vehicle, the suction port 11 of the oil pump 10 is provided with the air suction valve 20. The air suction valve 20 includes the first communication passage 21 which communicates with the atmosphere side 100, the second communication passage 22 which communicates with the suction port 11, and the valve mechanism (open/close mechanism) 23 which is capable of switching between opening and closing of communication between the first communication passage 21 and the second communication passage 22. The air suction valve 20 is configured to open the valve mechanism 23 when the oil suction pressure of the oil pump 10 becomes a negative pressure lower than or equal to the predetermined pressure, and air sucked through the air suction valve 20 is thereby mixed into the oil which is sucked from the oil bath 2 through the suction pipe 30.

The oil suction device 1 in the present embodiment has a configuration in which the above-described air suction valve 20 is provided in a suction section in which oil in the oil bath 2 is sucked by the oil pump 10, and when the oil suction pressure of the oil pump 10 becomes a negative pressure lower than or equal to the predetermined pressure, air is sucked by the oil pump 10 through the air suction valve 20 to reduce the driving torque of the oil pump 10. Thus, it is possible to reduce a pump driving torque particularly for an excessive amount of discharge in a high rotation region with a rotation rate exceeding the predetermined rotation rate. Therefore, the driving torque of a driving source which transmits rotation to the oil pump 10 may be reduced, and loss to the driving source may be effectively reduced.

In this manner, a configuration is adopted in which the air suction valve 20 is provided in a suction section in which oil in the oil bath 2 is sucked by the oil pump 10, the air suction valve 20 serving as a mechanism which changes the distribution (selectively sucks air and oil) between the amount of suction of oil in the oil bath 2 and the amount of suction of air, and thus the driving torque of the oil pump 10 is intentionally reduced by causing the oil pump 10 to suck air. That is, by providing a unit for sucking air on a suction path of the oil pump 10, an excessive amount of oil sucked by the oil pump 10 may be regulated when the suction pressure of the oil pump 10 is a negative pressure lower than or equal to the predetermined pressure, and thus a torque necessary for driving the oil pump 10 may be reduced. This makes it possible to reduce a pump driving torque particularly for an excessive amount of discharge in a high rotation region with a rotation rate exceeding the predetermined rotation rate. Consequently, the driving torque of the engine (driving source) that drives the oil pump 10 may be effectively reduced.

In the above-described oil suction device, the air suction valve 20 includes the valve element 25 that opens and closes between the first communication passage 21 and the second communication passages 22, and the coil spring (urging unit) 26 that urges the valve element 25 to a closed position. When the oil suction pressure of the oil pump 10 becomes a negative pressure lower than or equal to a predetermined pressure, the valve element 25 moves against the urging force of the coil spring 26 from the closed position to the open position by a force applied to the valve element 25.

With this configuration, when the suction pressure of the oil pump 10 becomes higher than or equal to the predetermined pressure, air may be sucked into the oil pump 10 using a simple configuration with a less number of components.

So far, the embodiment of the present disclosure has been described, however, the present disclosure is not limited to the above-described embodiment and various modifications may be made in a scope of the technical concepts described in the claims, the description and the drawings. For example, the specific structure of the air suction valve 20 in the above-described embodiment is an example. The air suction unit included in the oil suction device according to an embodiment of the present disclosure is not limited to have the structure as in the air suction valve 20 and may have another structure as long as the air suction unit has a structure capable of switching between open and closed positions according to a suction pressure of the oil pump. In the above-described embodiment, the case has been illustrated in which the air suction valve is provided in the suction port of the oil pump. However, the air suction unit according to an embodiment of the present disclosure may be provided at a position other than the position specified in the embodiment as long as the air suction unit is provided in the suction section in which oil in the oil reservoir is sucked by the oil pump (pump unit).

Provided is an oil suction device of a vehicle according to an embodiment of the present disclosure, the oil suction device (1) having a mechanical oil pump (10) which is driven by rotation transmitted from a driving source of the vehicle and configured to suck and pump oil in an oil reservoir (2) to the oil pump (10), the oil suction device including an air suction unit (20) which is provided in a suction section in which oil in the oil reservoir (2) is sucked by a suction unit (11) of the oil pump (10), the air suction unit (20) including a first communication passage (21) which communicates with an atmosphere side (100), a second communication passage (22) which communicates with the suction unit (11) of the oil pump (10), and an opening and closing mechanism (23) which is capable of switching between opening and closing of communication between the first communication passage (21) and the second communication passage (22). When an oil suction pressure (P) of the oil pump (10) becomes a negative pressure lower than or equal to a predetermined pressure (P1), the opening and closing mechanism (23) is opened to cause air sucked through the air suction unit (20) to be mixed into oil which is sucked from the oil reservoir (2) through a suction pipe (30).

The oil suction device of a vehicle according to an embodiment of the present disclosure has a configuration in which the above-described air suction unit is provided in a suction section in which oil in the oil reservoir is sucked by the suction unit of the oil pump, and thereby when the oil suction pressure of the oil pump becomes a negative pressure lower than or equal to the predetermined pressure, air is sucked by the oil pump through the air suction unit to reduce the driving torque of the oil pump. With this configuration, it is possible to reduce a pump driving torque particularly for an excessive amount of discharge in a high rotation region with a rotation rate exceeding a predetermined rotation rate. Therefore, the driving torque of a driving source which transmits rotation to the oil pump may be reduced, and loss to the driving source may be effectively reduced.

The above-described air suction unit has a structure which allows switching between enabling and disabling of suction of air into the oil pump according to an oil suction pressure. Thus, when the rotation rate of the oil pump is in a high rotation region and the suction negative pressure increases, air may be mixed into the oil which is to be sucked in the oil pump. Therefore, it is possible to reduce an increase in the amount of sucked oil in a high rotation region of the oil pump, and an effect of reduction in pump drive force and an effect of decrease in suction negative pressure are achieved. Consequently, the driving torque of the driving source may be reduced with a simple configuration.

In the above-described oil suction device, the opening and closing mechanism (23) includes: a valve element (25) configured to open and close between the first communication passage (21) and the second communication passages (22); and an urging unit (26) configured to urge the valve element (25) to a closed position. When the oil suction pressure (P) of the oil pump (10) becomes a negative pressure lower than or equal to the predetermined pressure (P1), the valve element (25) moves against an urging force of the urging unit (26) from the closed position to an open position.

With this configuration, when the suction pressure of the oil pump becomes higher than or equal to the predetermined pressure, air may be sucked into the oil pump using a simple configuration with a less number of components. The symbols in the above parentheses are provided so that the symbols of the components in the below-described embodiment are each illustrated as an example in the present disclosure.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

1. An oil suction device of a vehicle, the oil suction device having a mechanical oil pump which is driven by rotation transmitted from a driving source of the vehicle and configured to suck and pump oil in an oil reservoir to the oil pump, the oil suction device comprising

an air suction unit which is provided in a suction section in which oil in the oil reservoir is sucked by a suction unit of the oil pump,

the air suction unit including a first communication passage which communicates with an atmosphere side, a second communication passage which communicates with the suction unit of the oil pump, and an opening and closing mechanism which is capable of switching between opening and closing of communication between the first communication passage and the second communication passage,

wherein when an oil suction pressure of the oil pump becomes a negative pressure lower than or equal to a predetermined pressure, the opening and closing mechanism is opened to cause air sucked through the air suction unit to be mixed into oil which is sucked from the oil reservoir through a suction pipe.

2. The oil suction device of a vehicle according to claim 1,

wherein the opening and closing mechanism includes:

a valve element configured to open and close between the first communication passage and the second communication passages; and

an urging unit configured to urge the valve element to a closed position,

wherein when the oil suction pressure of the oil pump becomes a negative pressure lower than or equal to the predetermined pressure, the valve element moves against an urging force of the urging unit from the closed position to an open position.

3. An oil suction device of a vehicle, comprising:

a mechanical oil pump to be driven by a driving source of the vehicle and having a suction portion;

a first conduit connected to the suction portion of the mechanical oil pump;

a second conduit connected to an oil reservoir; and

an air suction device comprising: a first communication passage which communicates with an atmosphere side; a second communication passage which communicates with the first conduit and the second conduit; and an opening and closing mechanism configured to connect or disconnect the first communication passage and the second communication passage, the opening and closing mechanism connecting the first communication passage and the second communication passage in a case in which an oil suction pressure in the oil pump becomes a negative pressure lower than or equal to a predetermined pressure.

4. The oil suction device of a vehicle according to claim 3,

wherein the opening and closing mechanism includes a valve element configured to connect or disconnect the first communication passage and the second communication passages, and an urging device configured to urge the valve element to a closed position at which the first communication passage and the second communication passages are disconnected, and

wherein when the oil suction pressure of the mechanical oil pump becomes a negative pressure lower than or equal to the predetermined pressure, the valve element moves against an urging force of the urging device from the closed position to an open position at which the first communication passage and the second communication passages are connected.

5. The oil suction device of a vehicle according to claim 3,

wherein when a pump rotation rate of the mechanical oil pump is higher than or equal to a predetermined rotation rate, the oil suction pressure of the mechanical oil pump becomes a negative pressure lower than or equal to the predetermined pressure.