JP7801889B2 - Hydraulic Control Circuit - Google Patents

Description

The present invention relates to a hydraulic control circuit.

Conventionally, automobiles have been equipped with a mechanical oil pump driven by a drive device such as an engine as a pressure source to supply hydraulic pressure to automatic transmissions and other devices. Patent Document 1 discloses a hydraulic control device that, in addition to a mechanical oil pump, is equipped with an electric oil pump that operates when the engine is stopped.

JP 2016-65588 A

If a mechanical oil pump, which has difficulty in stabilizing the discharge pressure, is used as the pressure supply source, excessive pressure may be applied to the controlled device to which the oil is supplied, which could place a strain on the device.

In consideration of the above circumstances, one object of the present invention is to provide a hydraulic control circuit that can efficiently prevent excessive pressure from being applied to the object to which oil is supplied.

One aspect of the hydraulic control circuit of the present invention is a hydraulic control circuit that connects an oil pump to a target to which oil pressurized by the oil pump is supplied. The hydraulic control circuit includes a first oil passage that connects the discharge port of the oil pump to the target, a second oil passage that branches off from the first oil passage and connects to the intake port of the oil pump, and a flow control valve provided in the path of the second oil passage. The first oil passage has a first orifice downstream of the branch point with the second oil passage. The opening of the flow control valve is adjusted according to the difference between the pressure in the first oil passage downstream of the first orifice and the pressure in the second oil passage.

The above aspect of the present invention provides a hydraulic control circuit that can efficiently prevent excessive pressure from being applied to the oil supply target.

FIG. 1 is a diagram illustrating a schematic configuration of a hydraulic control circuit according to one embodiment. FIG. 2 is a cross-sectional view of a flow control valve according to an embodiment in a closed state. FIG. 3 is a schematic cross-sectional view of the flow control valve of the embodiment in an open state.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically showing the configuration of a hydraulic control circuit 1 according to this embodiment.
The hydraulic control circuit 1 is a circuit that connects an oil pump 2 and a supply target 9 to which oil pressurized by the oil pump 2 is supplied. Examples of the supply target 9 to which hydraulic pressure is supplied by the hydraulic control circuit 1 include a clutch device, an automatic transmission, and the like.

The hydraulic control circuit 1, oil pump 2, and supply target 9 are mounted on a vehicle powered by a motor, such as a hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHV), or electric vehicle (EV). The hydraulic control circuit 1 may also be mounted on a vehicle with a power source other than a motor, such as an internal combustion engine.

The oil pump 2 in this embodiment is a mechanical pump. The oil pump 2 is, for example, a gear pump such as an internal gear pump. The oil pump 2 discharges oil by being driven, for example, by a motor (not shown) for driving the vehicle. In this case, the rotational motion of the rotating shaft of the motor's power transmission gear is connected to the pump rotor of the oil pump 2, driving the oil pump 2. Note that the oil pump 2 may also be connected to and driven by an internal combustion engine mounted on, for example, a hybrid vehicle.

The oil pump 2 has an intake port 2b and an outlet port 2a. The oil pump 2 draws oil from the strainer 3 at the intake port 2b and supplies oil pressure to the supply target 9 at the outlet port 2a.

The hydraulic control circuit 1 includes a first oil passage 10, a first branch oil passage 11, a second oil passage 20, a second branch oil passage 21, a third oil passage 30, a third branch oil passage 31, an intake oil passage 40, a flow control valve 50, a line pressure regulating valve 60, and a strainer 3.

(1st oilway)
The first oil passage 10 connects the discharge port 2a of the oil pump 2 to the supply target 9. In the following description, the upstream side of the first oil passage 10 means the oil pump 2 side of the first oil passage 10, and the downstream side of the first oil passage 10 means the supply target 9 side of the first oil passage 10.

The second oil passage 20, the third oil passage 30, and the first branch oil passage 11 branch off from the first oil passage 10. Within the route of the first oil passage 10, the branch off point with the second oil passage 20 is called the first branch off point (branch off point) 10a, the branch off point with the third oil passage 30 is called the second branch off point 10b, and the branch off point with the first branch oil passage 11 is called the third branch off point 10c. The first branch off point 10a, the second branch off point 10b, and the third branch off point 10c are arranged in this order from the upstream side to the downstream side of the first oil passage 10.

The first oil passage 10 has a first orifice 19. The first orifice 19 is the portion where the cross-sectional area of the first oil passage 10 becomes smaller. The pressure of the oil flowing through the first oil passage 10 decreases as it passes through the first orifice 19. Therefore, the pressure of the oil upstream of the first orifice 19 is higher than the pressure of the oil downstream of the first oil passage 10. In the first oil passage 10, a first branch portion 10a is located upstream of the first orifice, and a second branch portion 10b and a third branch portion 10c are located downstream of the first orifice 19. In other words, the first orifice 19 is located downstream of the first branch portion 10a and upstream of the second branch portion 10b and the third branch portion 10c.

A first filter 71 is disposed in the path of the first oil passage 10. The first filter 71 filters the oil flowing through the first oil passage 10 and removes fine debris contained in the oil. The first filter 71 is located downstream of the first branch 10a, first orifice 19, and second branch 10b, and upstream of the third branch 10c. The oil flowing through the first oil passage 10 generates pressure loss in the first filter 71. However, the pressure loss in the first filter 71 can be considered sufficiently small, similar to the pressure loss due to the piping, and will be ignored in this explanation.

(First branch oil passage)
The first branch oil passage 11 branches off from the first oil passage 10 downstream of the first orifice 19. Therefore, the pressure of the oil in the first branch oil passage 11 is approximately equal to the pressure of the oil in the first oil passage 10 downstream of the first orifice 19. The first branch oil passage 11 is also connected to a third port 50c of the flow control valve 50.

(Second oilway)
The second oil passage 20 branches off from the first oil passage 10 upstream of the first orifice 19. A flow control valve 50 is disposed in the path of the second oil passage 20. The second oil passage 20 has an upstream region 25 that is a region upstream of the flow control valve 50, and a downstream region 26 that is a region downstream of the flow control valve 50.

The upstream region 25 of the second oil passage 20 extends from the first branch 10a of the first oil passage 10 to the flow control valve 50. The upstream region 25 is connected to the first port 50a of the flow control valve 50. The pressure of the oil in the upstream region 25 is approximately equal to the pressure of the oil in the first oil passage 10 upstream of the first orifice 19.

A second branch oil passage 21 branches off from the upstream region 25 of the second oil passage 20. The portion of the second oil passage 20 where it branches off from the second branch oil passage 21 is called the fourth branch portion 20a. A second filter 72 is disposed in the upstream region 25 of the second oil passage 20, upstream of the fourth branch portion 20a. The second filter 72 filters the oil flowing through the second oil passage 20. The pressure loss in the second filter 72 is sufficiently small that it can be ignored here.

The downstream region 26 of the second oil passage 20 extends from the flow control valve 50 to the intake oil passage 40. The downstream region 26 is connected to the second port 50b of the flow control valve 50. The downstream region 26 is also connected to the intake port 2b of the oil pump 2 via the intake oil passage 40. Therefore, the second oil passage 20 is an oil passage that branches off from the first oil passage 10 and connects to the intake port 2b of the oil pump 2.

(Second branch oil passage)
The second branch oil passage 21 branches off from the second oil passage 20 at a fourth branch portion 20a provided in the upstream region 25 of the second oil passage 20. That is, the second branch oil passage 21 branches off from the second oil passage 20 on the upstream side of the flow control valve 50. The second branch oil passage 21 is connected to a fourth port 50d of the flow control valve 50.

The second branch oil passage 21 has a second orifice 29. The second orifice 29 is the part where the cross-sectional area of the second branch oil passage 21 becomes smaller. When oil flows through the second branch oil passage 21, the pressure of the oil decreases as it passes through the second orifice 29. The second orifice 29 increases the pressure loss of the oil in the second branch oil passage 21, slowing the flow of oil within the second branch oil passage 21.

(3rd oilway)
The third oil passage 30 branches off from the first oil passage 10 downstream of the first orifice 19. A line pressure regulating valve 60 is disposed in the path of the third oil passage 30. The third oil passage 30 has an upstream region 35 that is an upstream region of the line pressure regulating valve 60, and a downstream region 36 that is a downstream region of the line pressure regulating valve 60.

The upstream region 35 of the third oil passage 30 extends from the second branch 10b of the first oil passage 10 to the line pressure regulating valve 60. The upstream region 35 is connected to the first port 60a of the line pressure regulating valve 60. The pressure of the oil in the upstream region 35 is roughly the same as the pressure of the oil downstream of the first orifice 19 in the first oil passage 10.

A third branch oil passage 31 branches off from the upstream region 35 of the third oil passage 30. The part of the third oil passage 30 where it branches off from the third branch oil passage 31 is called the fifth branch section 30a.

The downstream region 36 of the third oil passage 30 extends from the line pressure regulating valve 60 to the intake oil passage 40. The downstream region 36 is connected to the second port 60b of the line pressure regulating valve 60. The downstream region 36 is also connected to the intake port 2b of the oil pump 2 via the intake oil passage 40. Therefore, the third oil passage 30 is an oil passage that branches off from the first oil passage 10 and connects to the intake port 2b of the oil pump 2.

(Third branch oil passage)
The third branch oil line 31 branches off from the third oil line 30 at a fifth branch portion 30a provided in an upstream region 35 of the third oil line 30. That is, the third branch oil line 31 branches off from the third oil line 30 on the upstream side of the line pressure regulating valve 60. The third branch oil line 31 is connected to a third port 60c of the line pressure regulating valve 60.

(Line pressure adjusting valve)
The line pressure regulating valve 60 is provided in the path of the third oil passage 30. The line pressure regulating valve 60 has a first port 60a, a second port 60b, and a third port 60c. The first port 60a is connected to the upstream region 35 of the third oil passage 30. The second port 60b is connected to the downstream region 36 of the third oil passage 30. The third port 60c is connected to the third branch oil passage 31. A solenoid is disposed inside the line pressure regulating valve 60. The line pressure regulating valve 60 is driven by the pressure in the third branch oil passage 31 and the solenoid.

The line pressure regulating valve 60 adjusts the opening between the upstream region 35 and downstream region 36 of the third oil passage 30. As a result, the line pressure regulating valve 60 adjusts the flow rate of oil flowing through the third oil passage 30 and adjusts the pressure of the first oil passage 10. In other words, if the pressure in the first oil passage 10 becomes too high, the line pressure regulating valve 60 returns some of the oil to the intake port 2b of the oil pump 2 via the third oil passage 30.

(Suction oil path)
The oil intake passage 40 connects the strainer 3, which filters oil stored in an oil pan (not shown), to the intake port 2b of the oil pump 2. The downstream end 20b of the second oil passage 20 and the downstream end 30b of the third oil passage 30 are connected to the oil intake passage 40. Therefore, the oil passing through the strainer 3, the oil passing through the second oil passage 20, and the oil passing through the third oil passage 30 join together and are drawn into the intake port 2b of the oil pump 2.

(Flow control valve)
The flow control valve 50 is provided in the path of the second oil passage 20. The flow control valve 50 adjusts the flow rate of oil passing through the second oil passage 20 by changing the opening degree. The first branch oil passage 11 and the second branch oil passage 21 are also connected to the flow control valve 50. The oil in the first branch oil passage 11 and the second branch oil passage 21 is used to adjust the opening degree of the flow control valve 50.

In the following description, the state in which the flow control valve 50 is closed and blocks the second oil passage 20 between the upstream region 25 and the downstream region 26 is referred to as the closed state. Furthermore, the state in which the flow control valve 50 connects the second oil passage 20 between the upstream region 25 and the downstream region 26 is referred to as the open state.

Figure 2 is a schematic cross-sectional view of the flow control valve 50 in a closed state. Figure 3 is a schematic cross-sectional view of the flow control valve 50 in an open state.

The flow control valve 50 extends along the central axis J. The flow control valve 50 has a cylindrical housing portion 51 centered on the central axis J, a spool shaft 55 disposed inside the housing portion 51, and a spring 59 disposed inside the housing portion 51 on one axial side (left side in the figure) of the spool shaft 55.

The housing portion 51 has a cylindrical main body 52 and a lid portion 53. The cylindrical main body 52 is cylindrical with a bottom that opens to the other axial side (the right side in the figure). The cylindrical main body 52 has a bottom surface 52a that faces the other axial side (the right side in the figure). The opening of the cylindrical main body 52 is covered by the lid portion 53.

A cylindrical internal space S centered on the central axis J is provided inside the housing portion 51. The spool shaft 55 and spring 59 are disposed in the internal space S of the housing portion 51. The internal space S is divided by the spool shaft 55 into a first pressure chamber 51a, a spool chamber 51c, and a second pressure chamber 51b. That is, the first pressure chamber 51a, the spool chamber 51c, and the second pressure chamber 51b are provided inside the housing portion 51. The first pressure chamber 51a, the spool chamber 51c, and the second pressure chamber 51b are arranged in this order from one axial side to the other axial side.

The housing portion 51 is also provided with multiple ports (first port 50a, second port 50b, third port 50c, and fourth port 50d) extending radially from the internal space S. That is, the flow control valve 50 has the first port 50a, second port 50b, third port 50c, and fourth port 50d. The multiple ports 50a, 50b, 50c, and 50d are through holes provided from the outer periphery of the housing portion 51 toward the internal space S. The third port 50c, first port 50a, second port 50b, and fourth port 50d are arranged in this order from one axial side to the other axial side.

The first port 50a and the second port 50b are connected to the spool chamber 51c. The upstream region 25 of the second oil passage 20 is connected to the first port 50a. Meanwhile, the downstream region 26 of the second oil passage 20 is connected to the second port 50b. That is, the inlet (i.e., the upstream region 25) and outlet (i.e., the downstream region 26) of the second oil passage are connected to the spool chamber 51c.

The third port 50c is connected to the first pressure chamber 51a. The first branch oil passage 11 is also connected to the third port 50c. In other words, the first branch oil passage 11 is connected to the first pressure chamber 51a.

The fourth port 50d is connected to the second pressure chamber 51b. The second branch oil passage 21 is also connected to the fourth port 50d. In other words, the second branch oil passage 21 is connected to the second pressure chamber 51b.

The spool shaft 55 has a first land (land) 55a, a second land (land) 55b, a connecting shaft portion 55c, and a spring guide 55d.

The first land 55a and the second land 55b divide the internal space S of the housing portion 51. That is, the multiple lands 55a, 55b divide the internal space S of the housing portion 51 into a first pressure chamber 51a, a spool chamber 51c, and a second pressure chamber 51b. Each land 55a, 55b suppresses the movement of oil from an area on one axial side of itself to an area on the other axial side of itself in the internal space S.

The first land 55a is located on one axial side (left side in the figure) of the second land 55b. The axial dimension of the first land 55a is larger than the axial dimension of the second land 55b. A groove 55g is provided in the first land 55a. The groove 55g extends from the end face on the other axial side (right side in the figure) of the first land 55a to approximately the middle of the axial direction.

The connecting shaft portion 55c is located between the first land 55a and the second land 55b and connects them. The connecting shaft portion 55c extends in the axial direction around the central axis J. The outer diameter of the connecting shaft portion 55c is sufficiently smaller than the outer diameters of the first land 55a and the second land 55b.

The spring guide 55d is connected to the end face on one axial side (left side in the figure) of the first land 55a. The spring guide 55d extends axially around the central axis J. The outer diameter of the spring guide 55d is sufficiently smaller than the outer diameters of the first land 55a and the second land 55b. A spring 59 is disposed on the outer periphery of the spring guide 55d. The spring guide 55d guides the compression motion of the spring 59.

The spring 59 is a coil spring centered on the central axis J. The spring 59 is placed in the first pressure chamber 51a in a compressed state. The spring 59 contacts the bottom surface 52a of the cylindrical main body 52 of the housing portion 51 and the surface of the first land 55a facing one axial side (left side in the figure). The spring 59 pushes the spool shaft 55 toward the second pressure chamber 51b (right side in the figure).

The flow control valve 50 transitions between a closed state (Figure 2) and an open state (Figure 3) as the spool shaft 55 moves along the axial direction. In the closed state of the flow control valve 50 shown in Figure 2, the spool shaft 55 is positioned offset toward the other axial side (right side in the figure) in the internal space S of the housing portion 51. In the closed state of the flow control valve 50, the end face of the spool shaft 55 on the other axial side (right side in the figure) contacts the lid portion 53.

The closed state is achieved when the sum of the oil pressure in the first pressure chamber 51a and the spring force of the spring 59 becomes greater than the oil pressure in the second pressure chamber 51b, causing the spool shaft 55 to move axially to the other side (right side in the figure).

When the flow control valve 50 is closed, the outer surface of the first land 55a of the spool shaft 55 covers the opening of the first port 50a. Therefore, when the flow control valve 50 is closed, oil is prevented from flowing from the first port 50a into the spool chamber 51c. As a result, when the flow control valve 50 is closed, the second oil passage 20 is blocked.

The flow control valve 50 transitions from the closed state shown in Figure 2 to the open state shown in Figure 3 when the spool shaft 55 moves axially to one side (left side in the figure). As the spool shaft 55 moves axially to one side, the recessed groove 55g provided in the first land 55a gradually overlaps the opening of the first port 50a. This connects the first port 50a and the spool chamber 51c, allowing oil to flow from the first port 50a into the spool chamber 51c, and the oil in the spool chamber 51c then flows out from the second port 50b.

The overlapping area between the groove 55g of the first land 55a and the first port 50a gradually increases as the spool shaft 55 moves axially to one side (left side in the figure). In other words, the spool shaft 55 changes the opening area of the inlet as it moves axially. The flow control valve 50 changes the opening of the second oil passage 20 depending on the axial position of the spool shaft 55, thereby adjusting the flow rate of oil flowing through the second oil passage 20.

The open state shown in Figure 3 occurs when the oil pressure in the second pressure chamber 51b becomes greater than the sum of the oil pressure in the first pressure chamber 51a and the spring force of the spring 59, causing the spool shaft 55 to move axially to one side (left side in the figure).

In this embodiment, a first branch oil passage 11 is connected to the first pressure chamber 51a. The first branch oil passage 11 branches off from the first oil passage 10 downstream of the first orifice 19. Therefore, the pressure downstream of the first orifice 19 in the first oil passage 10 is supplied to the first pressure chamber 51a. In addition, in this embodiment, a second branch oil passage 21 is connected to the second pressure chamber 51b. The second branch oil passage 21 branches off from the second oil passage 20. Therefore, the pressure of the oil in the second oil passage 20 is supplied to the second pressure chamber 51b.

Accordingly, the flow control valve 50 of this embodiment adjusts its opening degree in accordance with the difference between the pressure downstream of the first orifice 19 in the first oil passage 10 and the pressure in the second oil passage 20. Furthermore, the second oil passage 20 branches off from the upstream side of the first orifice 19 in the first oil passage 10. Therefore, the flow control valve 50 increases its opening degree when the pressure difference between the oil before and after passing through the first orifice 19 in the first oil passage 10 is large, and decreases its opening degree when the pressure difference is small.

The pressure difference between the oil before and after the orifice depends on the flow rate of the oil passage in which the orifice is installed. In other words, when the flow rate of the oil passage is large, the pressure difference becomes large, and when the flow rate of the oil passage is small, the pressure difference becomes large and small.

The flow control valve 50 of this embodiment can increase the opening to increase the flow rate of oil passing through the second oil passage 20 when the flow rate of oil discharged from the discharge port 2a of the oil pump 2 increases. As a result, when the discharge rate of the oil pump 2 becomes excessive, a portion of the oil flowing through the first oil passage 10 can be returned to the suction port 2b of the oil pump 2 via the second oil passage 20. This prevents oil from being supplied to the supply target 9 at excessive pressure.

According to this embodiment, the discharge pressure of the oil pump 2 can be appropriately divided, preventing excessive load from being placed on the supply target 9. Furthermore, according to this embodiment, a second oil passage 20 that returns excess oil to the oil pump 2 can be independently provided upstream of the supply target 9. This prevents the supply target 9 from being affected by excess oil, stabilizing the operation of the supply target 9.

The flow control valve 50 of this embodiment automatically adjusts the opening degree by utilizing the pressure difference between the first oil passage 10 and the second oil passage 20. Therefore, compared to valves that use solenoids for control, there is no need to electrically control the opening degree, and the configuration of the hydraulic control circuit 1 can be simplified.

In the hydraulic control circuit 1 of this embodiment, by locating the first filter 71 in the first oil passage 10 upstream of the flow control valve 50, it is possible to effectively prevent excessive pressure from being applied to the first filter 71, and it is possible to reduce the size of the first filter 71.

In the flow control valve 50 of this embodiment, the spool shaft 55 operates based on the pressure difference between the first pressure chamber 51a and the second pressure chamber 51b. The first branch oil passage 11 is connected to the first pressure chamber 51a, and the second branch oil passage 21 is connected to the second pressure chamber 51b. Therefore, the flow control valve 50 of this embodiment adjusts its opening based on the pressure difference between the first branch oil passage 11 and the second branch oil passage 21.

In this embodiment, a first branch oil passage 11 and a second branch oil passage 21 are provided, branching off from the first oil passage 10 and the second oil passage 20, respectively, and are used to adjust the opening of the flow control valve 50. As a result, the flow of oil in the first branch oil passage 11 and the second branch oil passage 21, which are used to adjust the opening, is limited, allowing for stable operation of the flow control valve 50.

In this embodiment, the second branch oil passage 21 has a second orifice 29. The second orifice 29 restricts the flow of oil in the second branch oil passage 21, slowing the flow rate of the oil in the second branch oil passage 21. Therefore, even if the discharge pressure of the oil pump 2 increases suddenly, a sudden increase in pressure in the second pressure chamber 51b can be prevented, and unstable operation of the spool shaft 55 can be prevented.

In this embodiment, the flow control valve 50 adjusts the opening of the first port 50a, which is the oil inlet, by covering it with the first land 55a as the spool shaft 55 slides. However, the flow control valve 50 may also adjust the opening of the second port 50b, which is the outlet. The land used to adjust the opening may also be the second land 55b. In other words, the flow control valve 50 may be configured such that one of the multiple lands 55a, 55b changes the opening of at least one of the inlet and outlet as the spool shaft 55 slides along the axial direction. The lands 55a, 55b adjust the opening of the inlet and outlet by changing the opening area of the inlet and outlet within the flow control valve 50.

The hydraulic control circuit 1 shown in Figure 1 has not only the second oil passage 20 but also the third oil passage 30 as oil passages that return oil from the first oil passage 10 to the intake port 2b of the oil pump 2. As a result, the oil discharged from the oil pump 2 can be appropriately divided and flowed between the second oil passage 20 and the third oil passage 30, more efficiently preventing excessive load from being applied to the supply target 9.

In this embodiment, the downstream ends 20b, 30b of the second oil passage 20 and the third oil passage 30 are connected to the suction port 2b that connects the strainer 3 and the oil pump 2. Therefore, the oil returned to the oil pump 2 via the second oil passage 20 and the third oil passage 30 does not pass through the strainer 3. The oil flowing through the second oil passage 20 and the third oil passage 30 has already been sucked into the oil pump 2 via the strainer 3, so there is no need to pass it through the strainer 3 again. According to this embodiment, since the second oil passage 20 and the third oil passage 30 do not pass through the strainer 3, pressure loss is reduced compared to when the oil passes through the strainer 3, and efficient oil circulation can be achieved.

The above describes an embodiment of the present invention, but each configuration and combination thereof in the embodiment is merely an example, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiment.

1...hydraulic control circuit, 2...oil pump, 2a...discharge port, 2b...suction port, 3...strainer, 9...supply target, 10...first oil passage, 10a...first branch (branch), 11...first branch oil passage, 19...first orifice, 20...second oil passage, 20b, 30b...downstream end, 21...second branch oil passage, 29...second orifice, 30...third oil passage, 40...suction oil passage, 50...flow control valve, 51...housing portion, 51a...first pressure chamber, 51b...second pressure chamber, 51c...spool chamber, 55...spool shaft, 55a...first land (land), 55b...second land (land), 59...spring, 60...line pressure regulating valve, S...internal space

Claims (4)

A hydraulic control circuit that connects an oil pump and a supply target of oil pressurized by the oil pump,
a first oil passage connecting a discharge port of the oil pump to the supply target;
a second oil passage branching from the first oil passage and connected to a suction port of the oil pump;
a flow control valve provided in the second oil passage,
the first oil passage has a first orifice downstream of a branch point with the second oil passage,
an opening degree of the flow control valve is adjusted in accordance with a difference between a pressure downstream of the first orifice in the first oil passage and a pressure in the second oil passage ;
a first branched oil passage branching from the first oil passage downstream of the first orifice;
a second branched oil passage branching from the second oil passage on the upstream side of the flow control valve,
the flow control valve adjusts its opening degree based on a pressure difference between the first branch oil passage and the second branch oil passage;
The flow control valve is
A cylindrical housing portion;
a spool shaft disposed inside the housing portion,
the spool shaft has a plurality of lands that divide the internal space of the housing portion into a first pressure chamber, a spool chamber, and a second pressure chamber;
an inlet and an outlet of the second oil passage are connected to the spool chamber;
The first branched oil passage is connected to the first pressure chamber,
The second branch oil passage is connected to the second pressure chamber,
As the spool shaft slides along the axial direction, any one of the lands changes the opening degree of at least one of the inlet and the outlet,
the flow control valve is disposed in the first pressure chamber and has a spring that pushes the spool shaft toward the second pressure chamber.
Hydraulic control circuit. The second branch oil passage has a second orifice.
The hydraulic control circuit according to claim 1 . a third oil passage branching from the first oil passage downstream of the first orifice and connected to a suction port of the oil pump;
The hydraulic control circuit according to claim 1 or 2, further comprising: a line pressure regulating valve provided in the third oil passage. a strainer for filtering the oil;
an intake oil passage connecting the strainer and an intake port of the oil pump,
A downstream end of the second oil passage and a downstream end of the third oil passage are connected to the intake oil passage.
The hydraulic control circuit according to claim 3 .