CN111637221B

CN111637221B - Hydraulic control device

Info

Publication number: CN111637221B
Application number: CN202010127996.8A
Authority: CN
Inventors: 内野智司
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2019-03-01
Filing date: 2020-02-28
Publication date: 2021-11-09
Anticipated expiration: 2040-02-28
Also published as: JP7091271B2; CN111637221A; JP2020139622A

Abstract

The present invention relates to a hydraulic control device (10). The hydraulic control device (10) has a relief Valve (VR) to which a first oil flow (pressure P1), a second oil flow (pressure P2), and a portion of a third oil flow (pressure PH) are supplied. The relief Valve (VR) relieves a part of the third oil flow (pressure PH) to the first oil flow (pressure P1) in a stage where the difference (P1-P2) between the pressure (P1) of the first oil flow and the pressure (P2) of the second oil flow is equal to or less than a predetermined pressure. According to the present invention, the overtravel of the valve body of the conventional pressure control valve can be suppressed only by adding a simple relief valve, which is also advantageous in cost reduction.

Description

Hydraulic control device

Technical Field

The present invention relates to a hydraulic control device that controls hydraulic pressure supplied to a transmission.

Background

Japanese patent application laid-open No. 2015-200369 is directed to providing a hydraulic control device capable of efficiently driving an oil pump, the hydraulic control device supplying a hydraulic pressure to a supplied portion and a hydraulic pressure operating portion, wherein the supplied portion is supplied with a low hydraulic pressure; the hydraulic pressure working unit is supplied with a high hydraulic pressure, i.e., a high hydraulic pressure.

In order to solve the technical problem, japanese patent application laid-open No. 2015-200369 includes a large-capacity oil pump, a small-capacity oil pump, a first flow path, a second flow path, and a third flow path, wherein the small-capacity oil pump supplies a high hydraulic pressure to a hydraulic operation unit and has a capacity smaller than that of the large-capacity oil pump. The small-capacity oil pump further pressurizes the supplied hydraulic pressure and supplies the pressurized hydraulic pressure to the hydraulic working unit.

The first flow path is for supplying the hydraulic pressure supplied from the large capacity oil pump to the small capacity oil pump. The second flow path is for supplying the hydraulic pressure supplied from the small capacity oil pump to the hydraulic pressure operation section. The third flow path supplies the hydraulic pressure supplied from the large capacity oil pump to the hydraulic operating unit without passing through the small capacity oil pump. A pressure control valve is connected to a first flow path between the large-capacity oil pump and the small-capacity oil pump.

Disclosure of Invention

However, the small-capacity oil pump system is a system that reduces pump loss by rotating the small-capacity oil pump to maintain Pilot pressure (Pilot pressure) while lowering the discharge pressure of the large-capacity oil pump to a pressure for low-pressure working equipment. The pilot pressure is ensured by the discharge capacity of the low-capacity oil pump in a state where the discharge pressure is reduced by appropriately controlling the rotation speed of the low-capacity oil pump. Therefore, there are problems as follows: when a consumption flow rate exceeding the discharge capacity of the small-capacity oil pump is generated, the pilot pressure may drop to the discharge pressure ensured by the large-capacity oil pump.

In addition, in the case where the rotation speed of the small capacity oil pump is less than an appropriate value, there is a problem that the discharge pressure is not reduced to the pressure for the low pressure working apparatus. Therefore, in order to obtain the maximum fuel efficiency, the rotation speed of the small capacity oil pump is controlled to be greater than an appropriate value. Making the rotation speed of the small-capacity oil pump greater than the appropriate rotation speed is effective to reduce the above-described discharge pressure. However, the stroke position of the pressure control valve is caused to move largely compared to the case of the appropriate rotation speed. Therefore, the following problems occur: when the consumed flow rate is generated, the time taken for the pressure control valve to return to the normal position is increased, and as a result, the decrease in the pilot pressure is accelerated.

Therefore, it is considered to add a relief port to the conventional pressure control valve and to limit the maximum stroke position of the pressure control valve during the small capacity oil pump assist operation.

However, since a relief port (relief port) is added to a conventional pressure control valve, the opening area can be kept constant only during the small capacity oil pump assist operation. Therefore, the valve position that is always optimal for the temperature condition and the change in the discharge flow rate of the large capacity oil pump cannot be maintained. Further, since the hydraulic pressure drop amount has a certain range depending on the condition, it is necessary to correct the hydraulic pressure drop amount by control.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a hydraulic control device that can suppress an over stroke (over stroke) of a valve body of a conventional pressure control valve and is advantageous in cost reduction by adding a simple relief valve.

The technical scheme of the invention is that the hydraulic control device is provided with a mechanical oil pump, an electric oil pump and a pressure control valve, wherein the electric oil pump is provided with a motor; the pressure control valve is connected between the mechanical oil pump and the electric oil pump.

In addition, the hydraulic control device according to the present invention includes a first flow path that supplies an oil flow from the mechanical oil pump to the electric oil pump as a first oil flow, and a second flow path; the second flow path supplies the oil flow from the mechanical oil pump to a low-pressure working apparatus as a second oil flow.

In addition, the hydraulic control device according to the present invention includes a third flow path that supplies a third oil flow output from the electric oil pump to the transmission, and a fourth flow path; the fourth flow passage branches from the third flow passage halfway, and supplies a part of the third oil flow output from the electric oil pump to the pressure control valve.

In addition, according to an aspect of the present invention, the hydraulic control device includes a relief valve to which at least the first oil flow, the second oil flow, and the third oil flow are supplied. The relief valve relieves a portion of the third oil flow into the first oil flow in a stage where a difference between the pressure of the first oil flow and the pressure of the second oil flow is equal to or less than a predetermined pressure.

According to the present invention, it is possible to provide a hydraulic control device that can suppress overstroke of a valve body of a conventional pressure control valve and is advantageous in cost reduction by adding only a simple relief valve.

The above objects, features and advantages will be readily understood by the following description of the embodiments with reference to the accompanying drawings.

Drawings

Fig. 1 is a hydraulic circuit diagram showing a configuration of a hydraulic control device according to the present embodiment.

Fig. 2 is a sectional view schematically showing a sixth pressure control valve.

Fig. 3 is a hydraulic circuit diagram partially omitted to show a first operation of the relief valve.

Fig. 4 is a hydraulic circuit diagram partially omitted to show a second operation of the relief valve.

Fig. 5 is a timing chart showing a variation in hydraulic pressure of the hydraulic control apparatus.

Detailed Description

Next, an example of an embodiment of the hydraulic control apparatus according to the present invention will be described with reference to fig. 1 to 5.

First, as shown in fig. 1, the hydraulic control apparatus 10 according to the present embodiment includes a mechanical oil pump OPa (large capacity oil pump) driven by the internal combustion engine ENG and an electric oil pump OPb (small capacity oil pump); the electric oil pump OPb is driven by the motor MOT. The hydraulic control device 10 is used, for example, in a so-called belt-type or chain-type continuously variable transmission 12 (so-called Friction drive).

The continuously variable transmission 12 includes a pair of input-side pulleys Dv, a pair of output-side pulleys Dr, and a belt or a chain (not shown) capable of transmitting power between the input-side pulleys Dv and the output-side pulleys Dr.

The pair of input-side pulleys Dv are constituted by a pulley (movable-side pulley) that is movable along an input shaft (not shown) of the continuously variable transmission 12 and a pulley (fixed-side pulley) that is fixed. The side pressure of the movable side pulley of the input side pulley Dv changes in response to the supply of oil, and the width of the input side pulley Dv in the axial direction of the input shaft changes. In this way, the clamping force of the belt between the pair of input-side pulleys Dv is adjusted by adjusting the supplied oil.

The pair of output-side pulleys Dr have a pulley (movable-side pulley) that is movable along an output shaft (not shown) of the continuously variable transmission 12 and a pulley (fixed-side pulley) that is fixed. The side pressure of the movable pulley of the output pulley Dr changes according to the supply of the oil, and the width of the output pulley Dr in the axial direction of the output shaft changes. By adjusting the supplied oil in this manner, the belt clamping force between the pair of output-side pulleys Dr is adjusted.

Here, the lateral pressure of the input side pulley Dv and the output side pulley Dr refers to a pressure that presses the input side pulley Dv and the output side pulley Dr on the movable side toward the input side pulley Dv and the output side pulley Dr on the fixed side in the axial direction of the input shaft and the output shaft. When the lateral pressure increases and the clamping force increases, the winding radius of the belt on the input-side pulley Dv or the output-side pulley Dr increases. The speed ratio of the continuously variable transmission 12 is controlled by controlling the hydraulic pressure supplied to the input-side pulley Dv and the output-side pulley Dr (i.e., controlling the side pressure or the clamping force).

The input-side pulley Dv, the output-side pulley Dr, and the clutch 14 that operates at a high hydraulic pressure correspond to a hydraulic operating portion (high-pressure system). The clutch 14 is, for example, a forward/backward travel clutch or a start clutch of the forward/backward travel switching mechanism.

The hydraulic control device 10 includes first to sixth pressure control valves V1 to V6, first to ninth oil passages R1 to R9, and a relief valve VR.

The second pressure control valve V2 and the third pressure control valve V3 are pressure control valves capable of arbitrarily changing the hydraulic pressure in accordance with the current supplied to the linear solenoid. The second pressure control valve V2 and the third pressure control valve V3 are configured as so-called normally open valves. That is, the second pressure control valve V2 and the third pressure control valve V3 communicate the primary port (not shown) and the secondary port (not shown) in a state where the linear solenoid is not supplied with electric power. The fourth pressure control valve V4 and the fifth pressure control valve V5 are pilot-operated pressure control valves, and are pressure control valves capable of arbitrarily changing the hydraulic pressure by changing the pilot pressure supplied from the outside.

On the other hand, the oil flow from the mechanical oil pump OPa driven by the internal combustion engine ENG is supplied to the first oil passage R1 and the ninth oil passage R9 via a sixth pressure control valve V6, which will be described later. The oil flow supplied to the first oil passage R1 is discharged to the electric oil pump OPb. When a low hydraulic pressure (low hydraulic pressure) is supplied to the oil flow supplied to the ninth oil passage R9, the oil flow is discharged to the low-pressure work equipment 24 having a sufficiently low pressure. Examples of the low-pressure operating device 24 include an operating member that needs to be lubricated or cooled by oil, and a lock-up clutch of a torque converter that operates at a low pressure.

The electric oil pump OPb also pressurizes the hydraulic pressure supplied from the first oil passage R1, and outputs the hydraulic pressure to the second oil passage R2. The third oil passage R3 branched from the second oil passage R2 is connected to a sixth pressure control valve V6 described later. Further, a check valve 26 is provided between the first oil passage R1 and the third oil passage R3. The check valve 26 is provided to allow the oil to flow from the first oil passage R1 to the third oil passage R3 and to prevent the oil from flowing in the direction opposite to the direction.

The second oil passage R2 is connected to the fourth oil passage R4 and the fifth oil passage R5. The hydraulic pressure gauge 20 is provided to be able to measure the hydraulic pressure at the connection portion between the second oil passage R2 and the third oil passage R3.

The fourth oil passage R4 is connected to the first pressure control valve V1. The first pressure control valve V1 reduces the pressure of the hydraulic pressure supplied from the fourth oil passage R4 to a predetermined pressure. The first pressure control valve V1 supplies the depressurized hydraulic pressure to the second pressure control valve V2, the third pressure control valve V3, and the clutch 14 mounted on the vehicle, respectively.

The second pressure control valve V2 reduces the supplied hydraulic pressure to the pilot pressure of the fourth pressure control valve V4, and outputs the reduced hydraulic pressure to the fourth pressure control valve V4 through the sixth oil passage R6. The third pressure control valve V3 reduces the supplied hydraulic pressure to the pilot pressure of the fifth pressure control valve V5, and outputs the reduced hydraulic pressure to the fifth pressure control valve V5 through the seventh oil passage R7.

The fifth oil passage R5 is connected to the fourth pressure control valve V4 and the fifth pressure control valve V5. The fourth pressure control valve V4 reduces the hydraulic pressure supplied from the fifth oil passage R5 to a predetermined pressure corresponding to the pilot pressure supplied from the second pressure control valve V2, and supplies the reduced pressure to the input-side pulley Dv. When the hydraulic pressure of the input-side pulley Dv is equal to or higher than the predetermined pressure, the fourth pressure control valve V4 discharges the remaining amount of oil from a discharge port (not shown) of the fourth pressure control valve V4 to the eighth oil passage R8. Accordingly, the hydraulic pressure of the input-side pulley Dv is maintained at the predetermined pressure.

The fifth pressure control valve V5 reduces the hydraulic pressure supplied from the fifth oil passage R5 to a predetermined pressure corresponding to the pilot pressure supplied from the third pressure control valve V3, and supplies the reduced pressure to the output side pulley Dr. When the hydraulic pressure of the output side pulley Dr is equal to or higher than the predetermined pressure, the fifth pressure control valve V5 discharges the remaining amount of oil from a discharge port (not shown) of the fifth pressure control valve V5 to the eighth oil passage R8. Accordingly, the hydraulic pressure of the output side pulley Dr is maintained at the predetermined pressure.

When the width of the input-side pulley Dv is increased, oil is discharged from the input-side pulley Dv. The discharged oil flows into the fourth pressure control valve V4 and is discharged from a discharge port (not shown) of the fourth pressure control valve V4 to the eighth oil passage R8. When the width of the output side pulley Dr is increased, oil is discharged from the output side pulley Dr. The discharged oil flows into the fifth pressure control valve V5 and is discharged from a discharge port (not shown) of the fifth pressure control valve V5 to the eighth oil passage R8.

The oil discharged from the wider one of the input-side pulley Dv and the output-side pulley Dr flows to the eighth oil passage R8. The oil discharged at this time is oil that enters the oil chamber of the pulley in a pressurized state, and is in a pressurized state.

In the present embodiment, the sixth pressure control valve V6 is connected between the mechanical oil pump OPa driven by the internal combustion engine ENG and the first oil passage R1, and between the mechanical oil pump OPa and the ninth oil passage R9.

As shown in fig. 2, the sixth pressure control valve V6 includes a first spool body 30A (valve body) and a second spool body 30B inside. The second spool 30B is biased toward the first spool 30A by a first elastic member 32a formed of a spring. The first spool body 30A is biased by the second elastic member 32B to the side away from the second spool body 30B. The second elastic member 32B has a spring disposed between the first spool 30A and the second spool 30B.

The sixth pressure control valve V6 has six ports (a first port PT1 to a sixth port PT 6). The oil flow (pressure P1) from the mechanical oil pump OPa is supplied to the first port PT1 (first supply port). The second port PT2 (first discharge port) is provided at the same position in the axial direction as the first port PT1, and is connected to the first oil passage R1. The third port PT3 (second discharge port) is provided on a side farther from the second spool body 30B than the second port PT2, and is connected to a ninth oil passage R9 connected to the low-pressure working equipment 24.

The fourth port PT4 is provided at a position corresponding to the second spool body 30B and in proximity to the first spool body 30A. The fourth port PT4 is supplied with the pilot pressure for the fourth pressure control valve V4 output from the second pressure control valve V2, that is, the pilot pressure supplied through the sixth oil passage R6. The fifth port PT5 is provided on a side farther from the first spool body 30A than the fourth port PT 4. The fifth port PT5 is supplied with the pilot pressure for the fifth pressure control valve V5 output from the third pressure control valve V3, that is, the pilot pressure supplied through the seventh oil passage R7.

The sixth pressure control valve V6 compares the pilot pressure output from the second pressure control valve V2 with the pilot pressure output from the third pressure control valve V3, and causes either of the higher pilot pressures to act as a force that moves the first spool 30A in a direction away from the second spool 30B.

The sixth port PT6 (second supply port) is provided on a side farther from the second spool body 30B than the third port PT3, and is supplied with the pilot pressure PH of the oil flow in the third oil passage R3.

In addition, the first spool body 30A is formed with a first annular groove 34a and a second annular groove 34b at positions corresponding to the first port PT1 and the third port PT3, respectively. A first outer peripheral surface 36a of the first spool body 30A is formed between the first annular groove 34a and the second annular groove 34 b. A second outer peripheral surface 36B is formed on the second spool body 30B side from the terminal end of the first annular groove 34a (the terminal end of the second spool body 30B).

On the other hand, as shown in fig. 1, the relief valve VR is supplied with the first oil flow (pressure P1) from the second port PT2 of the sixth pressure control valve V6. The relief valve VR is supplied with the second oil flow (pressure P2) from the third port PT3 and a part of the oil flow (pilot pressure PH) from the third oil passage R3.

The relief valve VR relieves a part of the third oil flow (pressure PH) to the first oil flow (pressure P1) at a stage when the difference (P1-P2) between the pressure P1 of the first oil flow and the pressure P2 of the second oil flow is equal to or less than a predetermined pressure.

Specifically, the pressure relief valve VR has a first portion 40a and a second portion 40b, wherein the first portion 40a receives the pressure P1 of the first oil flow; the second portion 40b is opposite to the first portion 40a and receives the pressure P2 of the second oil flow and the pressure Psp generated by the spring 42.

Then, the relief valve VR relieves a part of the third oil flow (pressure PH) to the first oil flow (pressure P1) at a stage in which the electric oil pump OPb starts operating and has a relationship of P2+ Psp ≧ P1.

Here, the operation of the hydraulic control device 10 according to the present embodiment will be described with reference to fig. 3 and 4.

First, when the relationship P2+ Psp < P1 is satisfied, the relief valve VR is closed as shown in fig. 3, and the relief of a part of the third oil flow (pressure PH) to the first oil flow (pressure P1) is blocked. At this time, when the electric oil pump OPb is not driven, PH becomes P1.

Next, the state shown in fig. 4 is obtained when the relationship P2+ Psp ≧ P1 is present, but the situation does not change because PH is P1 when the electric oil pump OPb is not driven. When the electric oil pump OPb is driven, PH > P1, and therefore the relief valve VR relieves a part of the third oil flow (pressure PH) to the first oil flow (pressure P1). At this time, the position of the first spool 30A of the sixth pressure control valve V6 is adjusted to a pressure adjusting position, which is a position where the pressure PH is substantially equal to the pressure P2, without overstroking.

Next, the hydraulic action of the hydraulic control device 10 according to the present embodiment will be described with reference to fig. 5. In fig. 5, the variation of the pressure PH is indicated by a one-dot chain line, the variation of the pressure P1 is indicated by a two-dot chain line, the variation of the pressure P2 is indicated by a solid line, and the pressure level of the pressure P1 (PH relief region) for relieving the pressure PH to the pressure P1 is indicated by a broken line.

First, during a period (servo non-operation) T1 when the pressure PH is P1, even if the relief valve VR is opened as shown in fig. 4, there is no differential pressure between the pressure PH and the pressure P1, and therefore the relief valve VR does not exhibit the relief function (non-servo state) of the pressure PH to the pressure P1.

Further, even when the pressure PH > P1 is set after the time point T1 at which the electric oil pump OPb starts rotating, the relief valve VR is closed during the period T2 in which P2+ Psp ≧ P1 is not satisfied (see fig. 3). Therefore, the relief valve VR does not perform the relief function of the pressure PH to the pressure P1 (non-servo state).

Then, after time t1 when the electric oil pump OPb starts rotating, and after time t2 when P2+ Psp ≧ P1 is satisfied, that is, when the difference (P1-P2) between the pressure P1 and the pressure P2 becomes the pressure Psp or less, the relief valve VR releases the pressure PH to the pressure P1 (servo state).

After that, for example, when a consumption flow rate of the pressure PH equal to or larger than the relief amount of the pressure P1 occurs at the time point t3, the pressure PH decreases, but the pressure P1 also increases substantially simultaneously, and therefore, the amount of decrease in the hydraulic pressure can be reduced. As a result, the amount of movement of the first spool 30A of the sixth pressure control valve V6 can be reduced, and the influence of the control pressure on the pulley pressure due to the volume change can be reduced. After time t3 and after time t4 when P2+ Psp ≧ P1 are satisfied, relief from the pressure PH to the pressure P1 is performed by the relief valve VR (servo state).

As shown in the above example, the hydraulic control device 10 is set to the servo state and the non-servo state by the differential pressure between the pressure P1 and the pressure P2, and thus can realize the target action.

[ means for solving the problems to be solved by the embodiments ]

The technical means that can be grasped from the above-described embodiments are described below.

[1] The hydraulic control device (10) of the present embodiment includes a mechanical oil pump OPa, an electric oil pump OPb, a pressure control valve V6, a first flow path (first oil path R1), a second flow path (ninth oil path R9), a third flow path (second oil path R2), a fourth flow path (third oil path R3), and a relief valve VR, wherein the electric oil pump OPb includes an electric motor MOT; the pressure control valve V6 is connected between the mechanical oil pump OPa and the electric oil pump OPb; the first flow path (first oil path R1) supplies the oil flow from the mechanical oil pump OPa to the electric oil pump OPb as a first oil flow (pressure P1); the second flow path (ninth oil passage R9) supplies the oil flow from the mechanical oil pump OPa to the low-pressure working equipment 24 as a second oil flow (pressure P2); the third flow path (second oil path R2) supplies the third oil flow output from the electric oil pump OPb to the transmission 12; the fourth flow passage (third flow passage R3) branches from the third flow passage (second flow passage R2) at some midpoint, and supplies a part of the third oil flow (pressure PH) output from the electric oil pump OPb to the pressure control valve V6; the relief valve VR is supplied with at least the first oil flow (pressure P1), the second oil flow (pressure P2), and a part of the third oil flow (pressure PH), and when the difference (P1-P2) between the pressure P1 of the first oil flow and the pressure P2 of the second oil flow is equal to or less than a predetermined pressure, the relief valve VR relieves the part of the third oil flow (pressure PH) to the first oil flow (pressure P1).

Accordingly, it is possible to provide the hydraulic control device 10 that can suppress the overstroke of the valve body of the conventional pressure control valve and is advantageous in cost reduction by adding only a simple relief valve.

[2] In the present embodiment, the electric oil pump OPb starts operating at the stage at which the predetermined pressure is reached. That is, when the electric oil pump OPb does not start operating, the situation does not change because the pressure PH is equal to the pressure P1. By starting the operation of the electric oil pump OPb, a difference is generated between the pressure PH and the pressure P1, and the relief valve VR is able to relieve the third oil flow (pressure PH) into the first oil flow (pressure P1).

[3] In this embodiment, the pressure relief valve VR has a first portion 40a and a second portion 40b, wherein the first portion 40a receives the pressure P1 of the first oil flow; the second portion 40b faces the first portion 40a and receives the pressure P2 of the second oil flow and the pressure Psp generated by the spring 42, and the relief valve VR relieves a part of the third oil flow (pressure PH) to the first oil flow (pressure P1) in the relationship of P2+ Psp ≧ P1.

Even when the pressure PH > P1 is set after the point in time when the electric oil pump OPb starts rotating, the relief valve VR is in the closed state during the period T2 when P2+ Psp ≧ P1 is not satisfied, and therefore the relief function is not exhibited. The relief valve VR relieves the pressure PH to the pressure P1 after the point in time when the electric oil pump OPb starts rotating and after the point in time when P2+ Psp ≧ P1 is satisfied.

[4] In the present embodiment, the pressure control valve V6 has a first supply port (first port PT1) to which an oil flow from the mechanical oil pump OPa is supplied, a first discharge port (second port PT2), a second discharge port (third port PT3), a third supply port (sixth port PT6), and a valve body (first spool body 30A); the first discharge port (second port PT2) delivers the first oil flow (pressure P1) to the electric oil pump OPb; the second discharge port (third port PT3) delivers a second flow of oil (pressure P2) to the low pressure work device 24; the pilot Pressure (PH) from the fourth flow path (R3) is supplied to the third supply port (sixth port PT 6); the valve body (first spool 30A) is moved by the pilot Pressure (PH) supplied from the third supply port (sixth port PT 6).

It is contemplated that a pressure relief port may be added to the pressure control valve V6 to limit the maximum stroke position of the pressure control valve V6 when the electric oil pump OPb assists work.

However, since the relief port is added to the conventional pressure control valve V6, the opening area can only be kept constant during the auxiliary operation of the electric oil pump OPb, and the valve position that is always optimal for the temperature condition and the change in the discharge flow rate of the mechanical oil pump OPa cannot be kept. Further, since the hydraulic pressure drop amount has a certain range depending on the condition, it is necessary to correct the hydraulic pressure drop amount by control.

On the other hand, in the present embodiment, the overtravel of the valve body (first spool 30A) of the conventional pressure control valve V6 can be suppressed only by providing the conventional pressure control valve V6 and adding the simple relief valve VR. Further, the valve position which is always optimum for the temperature condition and the change in the discharge flow rate of the large capacity oil pump can be maintained. Further, as described above, when the consumption flow rate of the pressure PH to the relief amount of the pressure P1 or more is generated, the pressure PH is decreased, but the pressure P1 is also increased substantially at the same time, and therefore, the amount of decrease in the hydraulic pressure can be decreased. As a result, the amount of movement of the valve body (first spool 30A) of the pressure control valve V6 can be reduced, and the influence of the control pressure on the pulley pressure due to the volume change can be reduced.

The present invention is not limited to the above-described embodiments, and it goes without saying that modifications can be freely made within the scope not departing from the gist of the present invention.

Claims

1. A hydraulic control device (10) characterized in that,

comprising a mechanical oil pump (OPa), an electric oil pump (OPb), a pressure control valve (V6), a first flow path (R1), a second flow path (R9), a third flow path (R2), a fourth flow path (R3), and a relief Valve (VR),

the electric oil pump (OPb) has an electric Motor (MOT);

the pressure control valve (V6) is connected between the mechanical oil pump (OPa) and the electric oil pump (OPb);

the first flow path (R1) supplies the oil flow from the mechanical oil pump (OPa) to the electric oil pump (OPb) as a first oil flow (P1);

the second flow path (R9) supplies the oil flow from the mechanical oil pump (OPa) to a low-pressure working device (24) as a second oil flow (P2);

the third flow path (R2) supplies a third oil flow output from the electric oil pump (OPb) to a transmission (12);

the fourth flow path (R3) branches off from midway of the third flow path (R2) and supplies a Part (PH) of the third oil flow output from the electric oil pump (OPb) to the pressure control valve (V6);

the pressure relief Valve (VR) being supplied with at least the first oil flow (P1), the second oil flow (P2) and a Portion (PH) of the third oil flow,

the relief Valve (VR) relieves a Portion (PH) of the third oil flow into the first oil flow (P1) when a difference between the pressure (P1) of the first oil flow and the pressure (P2) of the second oil flow is equal to or less than a predetermined pressure.

2. The hydraulic control apparatus (10) according to claim 1,

the stage at which the predetermined pressure is reached is started by the electric oil pump (OPb).

3. The hydraulic control apparatus (10) according to claim 2,

the pressure relief Valve (VR) having a first portion (40a) and a second portion (40b), wherein,

said first portion (40a) receiving a pressure (P1) of the first oil flow;

the second portion (40b) is opposed to the first portion (40a) and receives the pressure (P2) of the second oil flow and the pressure (Psp) generated by the spring,

the pressure relief Valve (VR) relieves a Portion (PH) of the third oil stream (PH) to the first oil stream (P1) in the case of a relationship P2+ Psp ≧ P1.

4. The hydraulic control apparatus (10) according to claim 3,

the pressure control valve (V6) has a first supply port (PT1), a first exhaust port (PT2), a second exhaust port (PT3), a third supply port (PT6), and a valve body (30A),

the first supply port (PT1) is supplied with an oil flow from the mechanical oil pump (OPa);

the first discharge port (PT2) delivers the first oil flow (P1) to the electric oil pump (OPb);

the second discharge port (PT3) delivers the second oil flow (P2) to the low pressure working device (24);

the third supply port (PT6) is supplied with a pilot Pressure (PH) from the fourth flow path (R3);

the valve body (30A) is moved by the pilot Pressure (PH) supplied from the third supply port (PT 6).

5. The hydraulic control apparatus (10) according to claim 1,

said first portion (40a) receiving a pressure (P1) of the first oil flow;

6. The hydraulic control apparatus (10) according to claim 5,

7. The hydraulic control apparatus (10) according to claim 1,