JPWO2019077927A1 - Oil pump and engine cooling circuit - Google Patents

Abstract

The oil pump (20) is provided on the main flow path (11) that circulates the oil (Oi) from the oil pan (Op) in which the oil (Oi) is stored to the engine (En), and the main flow path (11). Form part of. The oil pump (20) includes a housing (30), a first hydraulic valve (50) for releasing oil (Oi) from the main flow passage (11) when the oil pressure is higher than a predetermined value, and a predetermined oil temperature. When the value is lower than the value, the thermo valve (60) that allows oil (Oi) to escape from the main flow path (11) and the first hydraulic valve (50) that is provided downstream of the thermo valve (60) are omitted. A second hydraulic valve (70) for releasing oil (Oi) from the main flow path (11) with the same hydraulic pressure is provided.

Description

The present invention relates to an engine cooling circuit having a hydraulic valve that releases oil when the hydraulic pressure exceeds a predetermined value.

For example, in vehicles, it is known to circulate oil to cool the engine. The oil is circulated by an oil pump which is arranged on the flow path and constitutes a part of the flow path. A hydraulic valve that releases oil when the hydraulic pressure exceeds a predetermined value may be disposed on the flow path. As a conventional technique related to such an engine cooling circuit, there is a technique disclosed in Patent Document 1.

An engine cooling circuit as shown in Patent Document 1, an oil pump that circulates oil that cools the engine, a first hydraulic valve that releases oil from a flow path when the hydraulic pressure exceeds a predetermined value, and A passage opening/closing valve which is provided separately from the first hydraulic valve and which can be opened and closed electrically, and a second hydraulic valve which is provided downstream of the passage opening/closing valve and releases oil from the passage when the hydraulic pressure exceeds a predetermined value. And are equipped with.

By using the hydraulic valve to suppress an excessive rise in hydraulic pressure, it is possible to reduce the load on the oil pump.

Japanese Utility Model Publication No. 02-034404

Generally, an engine cooling circuit is designed to exceed a required hydraulic pressure, which is a hydraulic pressure arbitrarily set according to the engine speed. From the viewpoint of engine protection and the like, a plurality of required hydraulic pressures are set according to the number of revolutions.

By providing the oil relief passage opening/closing valve in addition to the first hydraulic valve as shown in Patent Document 1, it is possible to return the oil even at a lower hydraulic pressure than the opening of the first hydraulic valve. The fuel efficiency can be improved. Note valve opening pressure of the second hydraulic valve is lower than the valve opening pressure of the first hydraulic valve (5 kgf / cm ^2), and ensure a minimum oil pressure (0.5~1kgf / cm ²⁾ required at the time of start-up It is stated that it is set to the extent possible.

The opening pressure of the second hydraulic valve is as wide as 0.5 to ⁵ kgf/cm ^2, and many trials and errors are required, which cannot be said to be easily implemented.

An object of the present invention is to provide an engine cooling technique capable of improving fuel efficiency performance and reliability.

According to the present invention, it is provided on the main flow path for circulating the oil from the oil pan in which the oil is stored to the engine, and constitutes a part of the main flow path,
In the housing
A first hydraulic valve that is opened so that the oil escapes from the main flow path when the hydraulic pressure is higher than a predetermined value;
When the oil temperature is higher or lower than a predetermined value, a thermo valve that is opened so that the oil can escape from the main flow path,
This thermo valve is provided downstream with respect to the oil flow direction, and is opened at a hydraulic pressure that is substantially the same as the predetermined value of the hydraulic pressure when the first hydraulic valve is opened, and the oil An oil pump is provided, which is provided with a second hydraulic valve that escapes from the main flow path.

Further, according to the present invention, a main flow path for circulating the oil from an oil pan in which oil is stored to an engine,
A first hydraulic valve provided in the main flow passage, which is in an open state so as to allow the oil to escape from the main flow passage when the hydraulic pressure is higher than a predetermined value;
A thermo valve provided in the main flow path, which is in an open state to allow the oil to escape from the main flow path when the oil temperature is higher or lower than a predetermined value,
This thermo valve is provided downstream with respect to the oil flow direction, and is opened at a hydraulic pressure that is the same as or lower than a predetermined value of the hydraulic pressure when the first hydraulic valve is opened. Is provided from the main flow path, and an engine cooling circuit is provided.

In the present invention, the second hydraulic valve is provided downstream of the thermo valve. Even if the thermo valve is in the open state, the second hydraulic valve will not open unless the predetermined hydraulic pressure is reached. The hydraulic pressure when the second hydraulic valve opens is, for example, substantially the same as the hydraulic pressure when the first hydraulic valve opens. As a result, the first and second hydraulic valves can be opened at substantially the same time. Depending on the oil temperature, it is possible to prevent the actual hydraulic pressure from greatly exceeding the required hydraulic pressure. As a result, fuel efficiency can be improved. In addition, since the hydraulic pressure when the second hydraulic valve opens is clear, the reliability of the engine cooling technology can be improved. Further, by making the hydraulic pressures when the second hydraulic valve and the first hydraulic valve open are substantially the same, it is possible to secure the minimum hydraulic pressure required by the auxiliary device device while maximizing the fuel efficiency effect. Can also

1 is a schematic diagram of an engine cooling circuit according to a first embodiment of the present invention. It is a front view of the oil pump shown in FIG. FIG. 3 is a sectional view of the oil pump shown in FIG. 2. FIG. 4 is a sectional view taken along line 4-4 of FIG. 2. 5A is a diagram for explaining the operation of the oil pump at low oil temperature and low oil pressure, FIG. 5B is a diagram for explaining the operation of the oil pump at low oil temperature and high oil pressure, and FIG. 5C is for high oil temperature. It is a figure explaining the operation of an oil pump. FIG. 6 is a front view of an oil pump used in an engine cooling circuit according to a second embodiment of the present invention. FIG. 7 is a sectional view taken along line 7-7 of FIG. 6.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description, the terms “upper, lower, left and right” refer to upper, lower, left and right with reference to the drawings.

<Example 1>
Please refer to FIG. The engine cooling circuit 10 is used, for example, in a vehicle. The engine cooling circuit 10 is a circuit for circulating the oil Oi stored in the oil pan Op and cooling the engine En by using the oil pump 20 provided on the main flow path 11.

Please refer to FIG. 2 to FIG. FIG. 2 shows the oil pump 20 with the lid removed. FIG. 3 is an oil pump shown by a cross section viewed from the same direction as FIG.

The oil pump 20 is a so-called internal gear pump. The oil pump 20 includes a housing 30, a drive shaft 22 that is rotated by the operation of an engine En (see FIG. 1 ), an inner rotor 23 that is rotated by the drive shaft 22, and an inner rotor that surrounds the inner rotor 23. An outer rotor 24 rotated by the rotor 23, a first hydraulic valve 50 that is opened when the oil pressure is higher than a predetermined value, and a thermo valve 60 that is opened when the oil temperature is lower than a predetermined value. A second hydraulic valve 70 provided downstream of the thermo valve 60 with respect to the oil flow direction is housed.

It should be noted that the thermo valve may be one that opens when the oil temperature is higher than a predetermined value.

The housing 30 includes a suction port 31 for sucking the oil pumped from the oil pan Op (see FIG. 1), a discharge port 32 for discharging the oil pumped by the inner rotor 23 and the outer rotor 24, and a first hydraulic pressure. A cylindrical hydraulic hole-shaped first hydraulic valve storage portion 33 in which the valve 50 is stored, and a first opening portion 34 and a second opening portion 35 in which oil is discharged by being evacuated in the first hydraulic valve storage portion 33. And a bypass passage 36 for guiding the oil discharged from the first opening portion 34 and/or the second opening portion 35 to the suction port 31, and a cylindrical valve-shaped thermovalve storage portion in which the thermovalve 60 is stored. 37, a circular hole-shaped third opening 38 formed to discharge oil from the thermo-valve housing 37, and the thermo-valve housing 37 through the third opening 38. A second hydraulic valve storage portion 41 in which the second hydraulic valve 70 is stored, and a round hole that is opened in the lower portion of the second hydraulic valve storage portion 41 to drop the oil in the oil pan Op (see FIG. 1). A fourth opening 42 in the shape of a circle.

Please refer to FIG. It can be said that the intake port 31 and the discharge port 32 are a part of a flow path for circulating the oil Oi in the engine En. That is, the suction port 31 and the discharge port 32 form a part of the main flow path 11. The bypass passage 36 does not form the main passage 11.

Please refer to FIG. The first opening 34 is formed in the shape of a round hole, and is formed closer to the discharge port 32 than the second opening 35. Therefore, when the first hydraulic valve 50 (see FIG. 3) operates, oil is discharged from the first opening 34 before the second opening 35.

Two second openings 35 are formed, and the opening area is continuously increased from a portion near the discharge port 32. The area of each of the second openings 35 is larger than that of the first opening 34.

Please refer to FIG. The second hydraulic valve storage portion 41 is formed in a cylindrical hole shape. The base end portion of the second hydraulic valve storage portion 41 is open to the outside. That is, it is not closed by the lid or the like. Please also refer to FIG. The second hydraulic valve storage portion 41 is located above the oil pan Op. Therefore, even when the oil reaches the base end portion of the second hydraulic valve storage portion 41 and is discharged to the outside, the oil falls into the oil pan Op. In other words, since the oil falls into the oil pan, it is not necessary to close it with a lid or the like.

The drive shaft 22 is connected to, for example, a crankshaft. The drive shaft 22 can be connected to any member such as a cam shaft in addition to the crank shaft. The axis CL1 of the drive shaft 22 extends substantially parallel to the axis CL2 of the second hydraulic valve storage portion 41.

Please refer to FIG. The first hydraulic valve 50 has a first hydraulic valve lid 51 that closes the base end portion of the first hydraulic valve storage portion 33, and one end abuts on the first hydraulic valve lid 51. A first hydraulic valve spring 52 and a first hydraulic valve valve body 53 which is biased by the first hydraulic valve spring 52 toward the tip of the first hydraulic valve storage portion 33. Have.

In a state where oil is not circulating, the tip of the first hydraulic valve housing portion 33 is closed by the first hydraulic valve valve body 53. When the flow rate of oil increases, a large hydraulic pressure is applied to the first hydraulic valve valve body 53. The oil pushes the first hydraulic valve valve body 53 downward in the drawing against the force of the first hydraulic valve spring 52. When the first hydraulic valve valve body 53 is pushed down to a position where it overlaps the first opening 34, a part of the oil flows from the first opening 34 to the bypass passage 36. Further, when the first hydraulic valve valve body 53 is pushed down by the hydraulic pressure and is pushed down to a position overlapping the second openings 35, 35 (see FIG. 2), the oil is discharged from the second openings 35, 35. And is discharged to the bypass 36. The oil that has flowed to the bypass passage 36 is returned to the suction port 31.

The thermo-valve 60 includes a thermo-valve lid 61 that closes the base end of the thermo-valve housing 37, a thermo-actuator 62 that has one end abutting against the thermo-valve lid 61 and expands and contracts depending on the temperature of oil, and the thermo-actuator. A thermo valve spring 63 whose one end is in contact with a flange portion 62 a formed on 62, and a thermo valve valve body 64 fixed to the tip of the thermo actuator 62 are provided.

The thermo valve valve body 64 has a cap shape, a plurality of upper holes 64a are formed in the upper portion of the cap, and a side wall portion 64b capable of opening and closing the third opening 38. In a state before operating the engine En (see FIG. 1 ), that is, in a state where the oil has a low temperature, the thermo valve valve body 64 opens the third opening 38.

Please refer to FIG. The second hydraulic valve 70 includes a C-shaped ring 71 fitted in a groove 41 a formed in the second hydraulic valve storage portion 41, and a second hydraulic valve seat portion 72 in contact with the C-shaped ring 71. And a second hydraulic valve spring 73 whose one end is in contact with the second hydraulic valve seat 72, and is urged toward the third opening 38 by the second hydraulic valve spring 73. Second hydraulic valve valve element 74 having a spherical shape.

The C-shaped ring 71 can be fitted into the groove portion 41a by facing the groove portion 41a in a state where the both ends of the C-shape are reduced so that they are close to each other, and releasing the reduced diameter force in the vicinity of the groove portion 41a. it can.

The second hydraulic valve seat portion 72 can employ a donut plate-shaped washer.

The third opening 38 is closed by the second hydraulic valve valve element 74 when the oil is not circulating. With this state as a reference, the fourth opening 42 is formed below the second hydraulic valve valve element 74 (including downward from the horizontal direction).

Please refer to FIG. FIG. 5A shows the thermo valve and the second hydraulic valve when the oil temperature is low and the oil pressure is low. FIG. 5B shows the thermo valve and the second hydraulic valve when the oil temperature is low and the oil pressure is high. FIG. 5C shows the thermo valve and the second hydraulic valve when the oil temperature is high.

Please refer to FIG. 5A. When the oil temperature is low, the thermo valve valve body 64 opens the third opening 38. On the other hand, when the oil pressure is low, the urging force of the second hydraulic valve spring 73 is larger than the force of the oil pushing the second hydraulic valve valve body 74. Therefore, the third opening 38 is closed by the second hydraulic valve valve body 74. The oil is prevented from flowing to the second hydraulic valve storage portion 41 side.

Please refer to FIG. 5B. When the oil temperature is low, the thermo valve valve body 64 opens the third opening 38. When the oil pressure is high, the force with which the oil pushes the second hydraulic valve valve body 74 is larger than the biasing force of the second hydraulic valve spring 73. The oil pushes the second hydraulic valve valve element 74 against the biasing force of the second hydraulic valve spring 73. The third opening 38 is opened and oil flows from the third opening 38 to the fourth opening 42. The oil that has passed through the fourth opening 42 falls into the oil pan Op (see FIG. 1).

Please refer to FIG. The second hydraulic valve valve body 74 operates along the axis line CL2 of the second hydraulic valve housing portion 41. That is, the axis CL2 can also be referred to as the operating axis CL2 of the second hydraulic valve valve body 74.

Please refer to FIG. 3 and FIG. 5B. The hydraulic pressure when the fourth opening 42 is opened is substantially the same as the hydraulic pressure when the first hydraulic valve valve body 53 is pushed down by the hydraulic pressure and the oil is discharged from the first opening 34.

Here, in order to be said to be substantially the same, the hydraulic pressure when the fourth opening 42 is opened is preferably ±40 kPa with respect to the hydraulic pressure when the first opening 34 is opened. ..

When the first hydraulic valve storage portion 33 is formed with a plurality of openings 34, 35 (see FIG. 2), the hydraulic pressure when the oil is discharged from the openings means the first opening. Is based on the hydraulic pressure when the is released.

Reference is made to FIG. 5C. When the oil temperature is high, the wax filled in the thermo actuator 62 expands and pushes out the rod 62b. Since the tip of the rod 62b is in contact with the thermo valve lid 61, the entire thermo actuator 62 is pushed down. The thermo valve valve body 64 fixed to the thermo actuator 62 is also lowered, and the side wall portion 64b closes the third opening portion 38. The third opening 38 is in a closed state regardless of the oil flow rate.

The present invention described above has the following effects.

Please refer to FIG. 5A and FIG. 5B. A second hydraulic valve 70 is provided downstream of the thermo valve 60. The second hydraulic valve 70 operates at a hydraulic pressure that is substantially the same as the hydraulic pressure when the first hydraulic valve 50 (see FIG. 3) operates. Even when the thermo valve 60 is in the open state, the second hydraulic valve 70 does not open unless the predetermined hydraulic pressure is reached. The hydraulic pressure when the second hydraulic valve 70 opens is substantially the same as the hydraulic pressure when the first hydraulic valve 50 opens. As a result, the first and second hydraulic valves 50, 70 can be opened substantially at the same time.

In the present invention, the second hydraulic valve 70 is used to suppress the discharge of oil from the thermo valve 60 to the outside when the predetermined hydraulic pressure is not reached. As a result, the hydraulic pressure when the second hydraulic valve 70 is opened becomes clear, so that the reliability of the engine cooling technique can be improved. Further, by making the hydraulic pressures when the second hydraulic valve 70 and the first hydraulic valve 50 open are substantially the same, the minimum fuel pressure required by the auxiliary equipment device is secured while maximizing the fuel efficiency effect. You can also do it.

By opening the second hydraulic valve 70 at a hydraulic pressure that is substantially the same as the hydraulic pressure when the oil is discharged from the first opening portion 34, the first and second hydraulic valves 50, 70 are opened at substantially the same time. can do. Since the thermo valve 60 can exert its effect in a wide rotation speed or in a wide hydraulic range, the fuel consumption effect is maximized and the maximum fuel consumption improvement effect can be obtained.

Please refer to FIG. The axis line CL1 of the drive shaft 22 and the operation axis line CL2 extend substantially parallel to each other. For the housing 30 of the oil pump 20, for example, an aluminum die cast product is used. By adopting a configuration in which the axis line CL1 of the drive shaft 22 and the operation axis line CL2 extend substantially parallel to each other, the molds can be drawn in the same direction. Therefore, it is not necessary to form the valve casing of the second hydraulic valve 70 (the second hydraulic valve storage portion 41) in a separate process. Further, when forming a hole through which the drive shaft 22 penetrates or a valve box of the second hydraulic valve 70 by cutting, the axes CL1 and CL2 are oriented in the same direction, and therefore the same cutting tool can be used for processing. it can. The housing 30 can be efficiently manufactured, and the productivity of the oil pump 20 can be improved.

<Example 2>
Second Embodiment A second embodiment of the present invention will be described next with reference to the drawings.

Please refer to FIG. 6 and FIG. FIG. 6 corresponds to FIG. 2, and FIG. 7 corresponds to FIG. The oil pump 20A according to the second embodiment is different from the oil pump 20 according to the first embodiment (see FIG. 2) in the structure of the housing 30A. Other basic configurations are common to the oil pump and the engine cooling circuit according to the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The oil pump 20A is provided on the main flow path 11 (see FIG. 1) of the engine cooling circuit 10 (see FIG. 1).

The third opening 38 is closed by the second hydraulic valve valve element 74 when the oil is not circulating. With this state as a reference, the fourth opening 42A is formed on the side of the second hydraulic valve valve body 74.

The housing 30A has a return flow passage 44A connecting the bypass passage 36 from the second hydraulic valve storage portion 41A. The fourth opening 42A can be said to be an inlet of the return flow passage 44A. The operating axis line CL2A of the second hydraulic valve storage portion 41A extends in the vertical direction.

When the oil temperature is low, the thermo valve valve body 64 opens the third opening 38. On the other hand, when the hydraulic pressure is low, the biasing force of the second hydraulic valve spring 73 is larger than the force of the oil pushing the second hydraulic valve valve body 74. Therefore, the third opening 38 is closed by the second hydraulic valve valve body 74. The oil is prevented from flowing to the second hydraulic valve storage portion 41 side.

When the temperature of the oil is low and the oil pressure is high, the force of the oil pushing the second hydraulic valve valve body 74 downward may be larger than the biasing force of the second hydraulic valve spring 73. The oil pushes the second hydraulic valve valve element 74 against the biasing force of the second hydraulic valve spring 73. The third opening 38 is opened, and the oil flows from the third opening 38 to the fourth opening 42A. The oil that has passed through the fourth opening 42A passes through the return flow passage 44A and reaches the bypass passage 36. The oil is returned from the bypass passage 36 to the suction port 31. A part of the oil that has not flowed to the return passage 44A falls from the bottom of the second hydraulic valve storage portion 41A to the oil pan Op (see FIG. 1).

The oil pump 20A according to the second embodiment also achieves the effects of the present invention.

Further, it has a return passage 44A for returning the oil discharged from the second hydraulic valve 70A to the suction port 31. When the oil is dropped on the oil pan Op, noise may be generated when the oil drops on the oil surface. With the configuration in which the oil flows through the return passage 44A, the quietness of the oil pump 20A during operation can be improved.

Further, the return passage 44A is connected to the suction port 31 via the bypass passage 36. The oil discharged from the second hydraulic valve 70A flows into the bypass passage 36 through which the oil discharged from the first hydraulic valve 50 passes. The housing 30A can be made compact as compared with the case where the flow paths are separately configured.

Further, the operation axis line CL2A of the second hydraulic valve storage portion 41A extends in the vertical direction. The bottom of the second hydraulic valve storage portion 41A is open. A part of the oil that has not flowed to the return passage 44A falls from the bottom of the second hydraulic valve storage portion 41A to the oil pan Op (see FIG. 1). As a result, it is possible to prevent the oil from staying in the second hydraulic valve storage portion 41A. Here, the amount of oil that drops into the oil pan Op is smaller than the amount of oil that flows into the return passage 44A. Therefore, even if excess oil is dropped into the oil pan Op, the effect on the quietness is small.

Although the engine cooling circuit has been described based on an example of being mounted on a vehicle, it can be applied to vehicles other than the vehicle, structures other than the vehicle, and the like. The present invention is applicable as long as the thermo valve operates according to the temperature of oil, and is not limited to those types.

In addition, not only internal gear pumps but also external gear pumps, vane pumps, piston pumps, etc. are used as the type of oil pump, and the oil is delivered by rotating the oil delivery means such as gears, vanes, pistons, etc. by the drive shaft. If it is an oil pump, it has the same effect as the embodiment.

In addition, the first and second hydraulic valves and the thermo valve have been described based on the example of being arranged in the oil pump, but in the middle of the main flow passage 11 outside the oil pump or in the engine En. It may be provided. If the flow rate of oil can be controlled based on the oil pressure and the temperature of oil, these valves can be arranged at arbitrary places.

At this time, when the second hydraulic valve 70 is arranged at a remote downstream position with respect to the first hydraulic valve 50, the hydraulic pressure released by the second hydraulic valve 70 is equivalent to the line resistance therebetween. It is preferable to set it low. As a result, the first and second hydraulic valves 50, 70 can be opened substantially at the same time. As a result, the effects prescribed by the present invention can be obtained.

In addition, the oil pump may be installed vertically long so that the first hydraulic valve 50 and the thermo valve 60 are located below the drive shaft 22. This is an oil pump having a shape inclined by 90° with the horizontal direction in FIG. 1 as the vertical direction. In this case, the thermoactuator 62 provided below the drive shaft 22 is arranged to lie in the horizontal direction and is more reliably immersed in the oil. As a result, the thermo actuator 62 can be reliably operated.

In addition, although the first opening 34 has been described based on the example formed at a portion closer to the discharge port 32 than the second opening 35, it may be formed at a far portion. The first opening 34 does not change that it is opened with a lower hydraulic pressure than the second opening 35, so the shape of the first hydraulic valve valve body is a known shape (for example, Japanese Patent Laid-Open No. 2010- 107036).

In the embodiment, the second hydraulic valve valve body 74 has a spherical shape, but it may have a cylindrical shape such as the first hydraulic valve valve body 53 and the thermo valve valve body 64. In addition, although the second hydraulic valve valve body 74 is directly driven by hydraulic pressure, it may be driven by electric control of a solenoid valve or the like.

That is, the present invention is not limited to the examples as long as the actions and effects of the present invention are exhibited.

The engine cooling circuit of the present invention is suitable for passenger vehicles.

10... Engine cooling circuit 11... Main flow passage 20, 20A... Oil pump 30, 30A... Housing 31... Suction port 34... First opening 35... Second opening 36... Bypass passage 44A... Return passage 50... 1st hydraulic valve 53... 1st hydraulic valve valve body 60... Thermo valve 70, 70A... 2nd hydraulic valve Op... Oil pan Oi... Oil En... Engine CL1... (Drive shaft) axis CL2... Operating axis

Claims (9)

It is provided on a main flow path that circulates the oil from an oil pan in which oil is stored to an engine, and constitutes a part of the main flow path.
In the housing
A first hydraulic valve that is opened so that the oil escapes from the main flow path when the hydraulic pressure is higher than a predetermined value;
When the oil temperature is higher or lower than a predetermined value, a thermo valve that is opened so that the oil can escape from the main flow path,
This thermo valve is provided downstream with respect to the oil flow direction, and is opened at a hydraulic pressure that is substantially the same as a predetermined value of the hydraulic pressure when the first hydraulic valve is opened. And a second hydraulic valve that allows the oil to escape from the main flow path. The oil pump according to claim 1,
A drive shaft for circulating the oil is inserted into the housing,
The axis of the drive shaft and the actuation axis along the direction in which the second hydraulic valve actuates extend substantially in parallel. The oil pump according to claim 1,
A first opening and a second opening, which are provided to be opened and closed by the first hydraulic valve and discharge the oil when opened;
The first opening and the second opening are arranged so that the first opening and the second opening are opened in this order,
The predetermined value of the hydraulic pressure when the first hydraulic valve is opened is the hydraulic pressure when the oil is discharged from the first opening. The oil pump according to claim 1,
The housing has a suction port for sucking the oil pumped from the oil pan,
A return flow path for returning the oil discharged from the second hydraulic valve to the suction port. The oil pump according to claim 4,
The housing has a bypass passage for returning the oil discharged from the first hydraulic valve to the suction port,
The return passage is connected to the suction port via the bypass passage. A main flow path for circulating the oil from an oil pan in which oil is stored to the engine,
A first hydraulic valve provided in the main flow path, which is in an open state so as to allow the oil to escape from the main flow path when the hydraulic pressure is higher than a predetermined value;
A thermo valve provided in the main flow path, which is in an open state to allow the oil to escape from the main flow path when the oil temperature is higher or lower than a predetermined value,
The thermo valve is provided downstream with respect to the flow direction of the oil, and is opened at a hydraulic pressure equal to or lower than a predetermined value of the hydraulic pressure when the first hydraulic valve is opened. And a second hydraulic valve that allows the oil to escape from the main flow path. The engine cooling circuit according to claim 6,
A first opening and a second opening, which are provided to be opened and closed by the first hydraulic valve and discharge the oil when opened;
The first opening and the second opening are arranged so that the first opening and the second opening are opened in this order,
The predetermined value of the hydraulic pressure when the first hydraulic valve is in the open state is the hydraulic pressure when the oil is discharged from the first opening. The engine cooling circuit according to claim 7, wherein
A suction port for sucking the oil pumped from the oil pan,
A return flow path for returning the oil discharged from the second hydraulic valve to the suction port. The engine cooling circuit according to claim 8, wherein
A bypass passage for returning the oil discharged from the first hydraulic valve to the suction port,
The return passage is connected to the suction port via the bypass passage.

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