Hydraulic circuit

Abstract

To provide a hydraulic circuit which can autonomously take an operation for eliminating a spool stick of a regulator valve when the line pressure is abnormally raised due to the spool stick (close lock) of the regulator valve, and can suppress the abnormal rise of the line pressure when the spool stick cannot be eliminated.SOLUTION: A hydraulic circuit 1 comprises: a regulator valve 30 for generating a line pressure by adjusting the hydraulic pressure of oil discharged from an oil pump 22; and a relief valve 40 having a first port 40c which is opened when the line pressure is equal to or higher than a first hydraulic pressure, and a second port 40d which is opened when the line pressure is equal to or higher than a second hydraulic pressure (>the first hydraulic pressure) to relieves the oil. In the regulator valve 30, when the hydraulic pressure of the oil which is relieved from the first port 40c of the relief valve 40 is applied to the regulator valve, a pressing force generated by the hydraulic pressure is imparted to the spool 30a in a valve-opening direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydraulic circuit. [Background technology]

[0002] Conventionally, vehicles have been equipped with, for example, an oil pump that is driven by an engine or an electric motor to discharge high-pressure oil, and the high-pressure oil discharged from the oil pump is regulated by a regulating valve (control valve) and supplied to various parts to realize the functions of the parts and to cool and lubricate them (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-267444 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, regulating valves, which regulate pressure by sliding a spool in the axial direction, are vulnerable to the entry of foreign matter (contamination). For example, if foreign matter gets caught in the regulating valve, the spool may stick and become locked closed (i.e., pressure regulation may become impossible), causing an abnormal increase in line pressure.

[0005] The present invention has been made to solve the above problems, and has an object to provide a hydraulic circuit that can autonomously take action to eliminate spool stick of the regulating valve when the regulating valve spool sticks (locked closed) and the line pressure rises abnormally, and that can suppress the abnormal rise in line pressure when the spool stick cannot be eliminated. [Means for solving the problem]

[0006] A hydraulic circuit according to one aspect of the present invention includes an oil pump which pressurizes and discharges oil stored in an oil pan, a regulating valve which generates line pressure by regulating the hydraulic pressure of the oil discharged from the oil pump, and a relief valve having a first port which opens when the line pressure is equal to or higher than a first hydraulic pressure and a second port which opens to relieve the oil when the line pressure is equal to or higher than a second hydraulic pressure which is higher than the first hydraulic pressure. The regulating valve has a spool which is accommodated so as to be freely slidable in the axial direction, and generates line pressure by regulating the amount of oil to be drained in accordance with the balance between the biasing force of a biasing member acting on the spool in a valve closing direction and the pushing force due to the hydraulic pressure of the oil discharged from the oil pump acting in a valve opening direction. Furthermore, when the hydraulic pressure of the oil relieved from the first port of the relief valve is applied, the pushing force due to the hydraulic pressure is applied to the spool in the valve opening direction.

[0007] According to a hydraulic circuit according to one aspect of the present invention, when the line pressure becomes equal to or higher than a first hydraulic pressure, the first port of the relief valve opens and the oil is relieved. Then, in the regulating valve, when the hydraulic pressure of the oil relieved from the first port of the relief valve is applied, a pushing force by the hydraulic pressure is applied to the spool in the valve opening direction (i.e., the direction to release the stick) (in addition to the pushing force by the discharge pressure of the oil pump). Therefore, when the line pressure rises to equal to or higher than the first hydraulic pressure, an action to release the spool stick (close lock) can be taken autonomously. Furthermore, when the spool stick cannot be released even by the above-mentioned releasing action and the line pressure becomes equal to or higher than a second hydraulic pressure higher than the first hydraulic pressure, the second port that relieves (releases) the oil opens and the oil is relieved. Thus, an abnormal rise in the line pressure can be suppressed. Effect of the Invention

[0008] According to the present invention, when the regulating valve becomes spool stuck (locked closed) and the line pressure rises abnormally, the regulator valve can take action to autonomously eliminate the spool stick, and when the spool stick cannot be eliminated even by the elimination action, it becomes possible to suppress the abnormal rise in line pressure. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing a configuration of a hydraulic circuit according to the embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the operation of the hydraulic circuit according to the embodiment (a diagram showing the flow of oil / supply oil passage (thick line) in a state in which "second hydraulic pressure>line pressure≧first hydraulic pressure"). [Diagram 3] FIG. 2 is a diagram for explaining the operation of the hydraulic circuit according to the embodiment (a diagram showing the oil flow / supply path (thick line) in a state where "line pressure≧second hydraulic pressure"). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals will be used for the same or corresponding parts. In each drawing, the same reference numerals will be used for the same elements, and duplicated explanations will be omitted.

[0011] First, the configuration of a hydraulic circuit 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of the hydraulic circuit 1. Note that, here, the hydraulic circuit 1 will be described as being applied to a series hybrid electric vehicle (SHEV).

[0012] The oil pan 20 stores oil for cooling and lubricating the first motor-generator 11 and the second motor-generator 12, and for lubricating the power split mechanism and the gears and bearings of the drive train. An oil pump 22 is provided to supply the oil stored in the oil pan 20 to the first motor-generator 11, the second motor-generator 12, etc.

[0013] The oil pump 22 is driven by either an engine (not shown) or an input from the axle, whichever has the higher rotation speed. More specifically, the oil pump 22 includes a first one-way clutch (not shown) that is connected to the engine so as to be able to transmit torque and transmits torque from the engine in one direction to the drive shaft of the oil pump 22, and a second one-way clutch (not shown) that is connected to the axle so as to be able to transmit torque and transmits torque from the axle in one direction to the drive shaft of the oil pump 22. The oil pump 22 is driven by either an input from the engine or an input from the axle, whichever has the higher rotation speed (so-called twin drive).

[0014] The oil pump 22 draws in oil stored in the oil pan 20 through the oil strainer 21, the suction oil passage 70, and the suction port 22a, pressurizes the oil, and discharges it from the discharge port 22b. As the oil pump 22, for example, a trochoid pump, a vane pump, or the like is suitably used.

[0015] The oil strainer 21 traps foreign matter (contamination) in the oil stored in the oil pan 20 and prevents the foreign matter from entering the regulating valve 30 or the like.

[0016] A line pressure oil passage 71 is connected to the discharge port 22b of the oil pump 22. A regulating valve (line pressure control valve) 30 is provided in the line pressure oil passage 71 to adjust (regulate) the oil pressure (discharge pressure) of the oil discharged from the oil pump 22 and generate the original pressure (line pressure) of the oil pressure required for each part.

[0017] The regulating valve 30 is connected to a line pressure oil passage 71, a drain oil passage 73 (connected to the suction oil passage 70) for discharging oil, and a first relief oil passage 72 connected to a first port 40c of the relief valve 40 described later. The regulating valve 30 accommodates a spool 30a therein so as to be slidable in the axial direction. A spring 30b (corresponding to the biasing member described in the claims) is disposed at one end of the spool 30a, and the amount of oil discharged from the line pressure oil passage 71 to the drain oil passage 73 (returned to the suction oil passage 70) is adjusted by driving the spool 30a in the axial direction according to the balance between the pressing force (discharge pressure x pressure receiving area) due to the discharge pressure of the oil pump 22 and the spring force (biasing force) of the spring 30b, thereby adjusting the line pressure.

[0018] That is, when the pushing force due to the discharge pressure of the oil pump 22 is larger than the spring force (biasing force) of the spring 30b (when the discharge pressure of the oil pump 22 becomes equal to or higher than a predetermined pressure), the regulating valve 30 communicates the line pressure oil passage 71 with the drain oil passage 73 and discharges the oil in the line pressure oil passage 71 through the drain oil passage 73 (returns it to the suction oil passage 70), thereby adjusting the line pressure. On the other hand, when the pushing force due to the discharge pressure of the oil pump 22 is smaller than the spring force (biasing force) of the spring 30b, the regulating valve 30 cuts off the communication between the line pressure oil passage 71 and the drain oil passage 73 and stops the discharge of oil from the line pressure oil passage 71.

[0019] A relief valve (relief valve or protection valve) 40 is connected to the line pressure oil passage 71. The relief valve 40 includes, for example, a valve body 40a and a spring 40b, and when the oil pressure (line pressure) in the line pressure oil passage 71 reaches or exceeds a predetermined pressure, the relief valve 40 releases (discharges) oil to lower the oil pressure in order to protect each part (hardware) to which the oil pressure is supplied.

[0020] In particular, the regulating valve 30 and the relief valve 40 have a function (mechanism) of autonomously canceling the spool stick (close lock) when the spool 30a of the regulating valve 30 sticks (close lock). Details will be described later.

[0021] An oil cooler 50 is provided in the line pressure oil passage 71 to cool the oil by exchanging heat between the oil and a cooling medium. In this embodiment, an air-cooled oil cooler that exchanges heat between the oil and the outside air is used as the oil cooler 50. Note that, instead of the air-cooled oil cooler, a water-cooled oil cooler that exchanges heat between the oil and cooling water (engine cooling water) may be used as the oil cooler 50. The oil cooled by the oil cooler 50 is discharged into a cooling oil passage 75 and sent to the first motor-generator 11 and the second motor-generator 12 through the cooling oil passage 75.

[0022] In addition, a portion of the oil sent to the oil cooler 50 through the line pressure oil passage 71 is supplied from just before (upstream of) the oil cooler 50 through the lubricating oil passage 74 to lubricated parts such as the above-mentioned power split mechanism and gears and bearings of the drive train.

[0023] Also, a bypass valve 60 is provided in parallel with the oil cooler 50. The bypass valve 60 is connected to a line pressure oil passage 71 and a cooling oil passage 75, and when the pressure difference between the inlet and outlet of the oil cooler 50 becomes equal to or greater than a predetermined pressure (for example, when the oil cooler 50 is blocked), the bypass valve 60 bypasses the oil cooler 50 and causes the oil supplied from the line pressure oil passage 71 to flow into the cooling oil passage 75. More specifically, the bypass valve 60 accommodates a ball (or valve body) 60a therein so as to be slidable in the axial direction. A spring 60b is disposed at the end of this ball (or valve body) 60a, and the opening and closing of the bypass valve 60 is controlled by moving the ball (or valve body) 60a axially in accordance with the balance between the pushing force (oil pressure × pressure-receiving area) due to the oil pressure at the inlet (line pressure oil passage 71) of the oil cooler 50, the pushing force (oil pressure × pressure-receiving area) due to the oil pressure at the outlet (cooling oil passage 75) of the oil cooler 50, and the spring force (biasing force) of the spring 60b.

[0024] That is, when the pushing force (oil pressure × pressure receiving area) due to the oil pressure at the inlet (line pressure oil passage 71) of the oil cooler 50 is greater than the resultant force of the pushing force (oil pressure × pressure receiving area) due to the oil pressure at the outlet (cooling oil passage 75) of the oil cooler 50 and the spring force (urging force) of the spring 60b, the bypass valve 60 opens to communicate the line pressure oil passage 71 and the cooling oil passage 75 (opens the bypass passage). On the other hand, when the pushing force (oil pressure × pressure receiving area) due to the oil pressure at the inlet (line pressure oil passage 71) of the oil cooler 50 is less than the resultant force of the pushing force (oil pressure × pressure receiving area) due to the oil pressure at the outlet (cooling oil passage 75) of the oil cooler 50 and the spring force (urging force) of the spring 60b, the bypass valve 60 closes (blocks the bypass passage).

[0025] Here, when the regulating valve 30 becomes spool stuck (locked closed) and the line pressure rises abnormally, the hydraulic circuit 1 can autonomously take action (resolution action) to eliminate the spool stick of the regulating valve 30, and has the function of suppressing the abnormal rise in line pressure when the spool stick cannot be eliminated even by the resolution action.

[0026] Therefore, the relief valve 40 has a first port 40c that opens (is open) when the line pressure is equal to or greater than a first hydraulic pressure (threshold value), and a second port 40d that opens to relieve (release) oil when the line pressure is equal to or greater than a second hydraulic pressure (threshold value) that is higher than the first hydraulic pressure.

[0027] More specifically, the relief valve 40 is configured, for example, to include a cylindrical valve case in which a first port 40c and a second port 40d are formed along the axial direction, a cylindrical valve body (spool) 40a that is accommodated inside the valve case so as to be able to slide freely in the axial direction, one end (end face) of which is connected to a line pressure oil passage and to which a pushing force in the valve opening direction due to line pressure acts (is applied) on the one end (end face), and a spring 40b (corresponding to a biasing member) that is disposed at the other end (end face) of the valve body 40a and applies a biasing force to the valve body 40a in the valve closing direction.

[0028] Therefore, when "line pressure<first hydraulic pressure", the relief valve 40 (first port 40c, second port 40d) is closed. When "second hydraulic pressure>line pressure≧first hydraulic pressure", only the first port 40c opens, and oil relieved from the first port 40c is supplied to the regulator valve 30 through the first relief oil passage 72. When "line pressure≧second hydraulic pressure", the second port 40d opens in addition to the first port 40c, and oil is relieved from the second port 40d (i.e., an abnormal rise in line pressure is suppressed).

[0029] As described above, the regulating valve 30 has a spool 30a housed therein so as to be slidable in the axial direction, and generates (adjusts) the line pressure by adjusting the amount of oil drained (discharge amount) in response only to the balance between the biasing force of the spring 30b acting on the spool 30a in the valve closing direction and the pushing force acting in the valve opening direction due to the hydraulic pressure (discharge pressure) of the oil discharged from the oil pump 22. In other words, the hydraulic circuit 1 can be suitably used in a hydraulic circuit using a mechanical (i.e., not electronically controlled) regulating valve 30.

[0030] Furthermore (in addition), the regulating valve 30 is configured such that when the oil pressure of the oil relieved from the first port 40c of the relief valve 40 is applied (supplied), a pushing force due to the oil pressure is applied (acts) on the spool 30a in the valve opening direction.

[0031] More specifically, the other end (end face) of the spool 30a constituting the regulating valve 30 is connected to the first port 40c of the relief valve 40 through a first relief oil passage 72. When the hydraulic pressure of the oil discharged from the first port 40c of the relief valve 40 is applied to the other end (end face), a pushing force due to the hydraulic pressure is applied to the spool 30a in the valve opening direction (i.e., in the direction to release the spool stick (close lock)).

[0032] In addition, at the other end of the regulating valve 30, in order to prevent the spool 30a from becoming difficult (or unable to slide) after the spool stick (close lock) is released, a discharge hole (breathing hole or relief hole) 30d is formed to discharge the oil relieved from the first port 40c of the relief valve and supplied through the first relief oil passage 72, while allowing the oil pressure of the oil relieved from the first port 40c of the relief valve 40 to be applied to the spool 30a (without preventing the application of the pressing force).

[0033] Next, the operation of the hydraulic circuit 1 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 and Fig. 3 are diagrams for explaining the operation of the hydraulic circuit 1. More specifically, Fig. 2 is a diagram showing the oil flow / supply oil path (thick lines) in a state where "second hydraulic pressure>line pressure≧first hydraulic pressure", and Fig. 3 is a diagram showing the oil flow / supply path (thick lines) in a state where "line pressure≧second hydraulic pressure".

[0034] First, when "first hydraulic pressure > line pressure," the spool 30a is driven in the axial direction in accordance with the balance between the biasing force of the spring 30b acting on the spool 30a in the valve closing direction and the pushing force (discharge pressure x pressure-receiving area) due to the hydraulic pressure (discharge pressure) of the oil discharged from the oil pump 22 acting in the valve opening direction, thereby adjusting the amount of oil drained from the line pressure oil passage 71 to the drain oil passage 73 (returned to the suction oil passage 70), thereby generating (regulating) the line pressure.

[0035] Next, for example, when the regulating valve 30 is stuck with a foreign object (contamination) and locked closed (i.e., pressure regulation is impossible), and the line pressure rises to "second hydraulic pressure>line pressure≧first hydraulic pressure", the first port 40c of the relief valve 40 opens and the oil is relieved, as shown in FIG. 2. Then, the oil is sent (input) to the regulating valve 30 through the first relief oil passage 72. When the hydraulic pressure of the oil relieved from the first port 40c of the relief valve 40 is applied (input) to the regulating valve 30a, a pushing force due to the hydraulic pressure is applied to the spool 30a in the valve opening direction (i.e., in the direction to release the spool stick) (in addition to the pushing force due to the discharge pressure of the oil pump 22). In this way, when the line pressure rises to the first hydraulic pressure or higher, the increased line pressure is used to autonomously release the spool stick (closed lock) (to return the spool 30a to its normal position).

[0036] Furthermore, if the spool stick (close lock) cannot be released even by the above-mentioned release operation and the "line pressure ≧ second hydraulic pressure (> first hydraulic pressure)" occurs, the second port 40d that relieves (releases) the oil opens and the oil is relieved as shown in Fig. 3. This suppresses an abnormal rise in the line pressure.

[0037] As described above in detail, according to this embodiment, when the line pressure becomes equal to or higher than the first hydraulic pressure, the first port 40c of the relief valve 40 opens, and the oil is relieved. When the hydraulic pressure of the oil relieved from the first port 40c of the relief valve 40 is applied to the regulating valve 30, a pushing force due to the hydraulic pressure is applied to the spool 30a in the valve opening direction (i.e., the direction to release the stick) (in addition to the pushing force due to the discharge pressure of the oil pump 22). Therefore, when the line pressure rises to equal to or higher than the first hydraulic pressure, the increased line pressure can be used to autonomously release the spool stick (close lock). Furthermore, when the spool stick (close lock) cannot be released even by the above-mentioned releasing operation and the line pressure becomes equal to or higher than the second hydraulic pressure higher than the first hydraulic pressure, the second port 40d that relieves (releases) the oil opens, and the oil is relieved. Therefore, an abnormal rise in the line pressure can be suppressed.

[0038] As a result, when the regulating valve 30 becomes spool stuck (locked closed) and the line pressure rises abnormally, the regulating valve 30 can autonomously take action to eliminate the spool stick, and when the spool stick cannot be eliminated even by the elimination action, it becomes possible to suppress the abnormal rise in line pressure.

[0039] According to this embodiment, the relief valve 40 includes a valve case in which a first port 40c and a second port 40d are formed along the axial direction, a valve body 40a that is accommodated inside the valve case so as to be axially slidable, one end (end face) of which is connected to the line pressure oil passage 71, and a pressing force in the valve opening direction due to the line pressure acts (is applied) on the one end (end face), and a spring 40b that is disposed at the other end of the valve body 40a and applies a biasing force in the valve closing direction to the valve body 40a. Therefore, when "second hydraulic pressure>line pressure≧first hydraulic pressure", the first port 40c opens, and oil is relieved from the first port 40c and can be supplied to the regulating valve 30. Furthermore, when "line pressure≧second hydraulic pressure", the second port 40d opens to relieve oil (i.e., an abnormal rise in line pressure is suppressed).

[0040] According to this embodiment, the other end (end face) of the spool 30a of the regulating valve 30 is communicated with the first port 40c of the relief valve 40, and when the hydraulic pressure of the oil relieved from the first port 40c of the relief valve 40 is applied to the other end (end face), a pushing force due to the hydraulic pressure is applied to the spool 30a in the valve opening direction. That is, when spool stick (close lock) occurs and the line pressure rises, and when the hydraulic pressure of the oil relieved from the first port 40c of the relief valve 40 is applied, a pushing force in the valve opening direction is applied to the spool 30a. Therefore, when spool stick (close lock) occurs, it is possible to autonomously resolve the spool stick.

[0041] According to this embodiment, while making it possible to apply a pushing force due to the oil pressure of the oil relieved from the first port 40c of the relief valve 40 to the spool 30a (without preventing the application of the pushing force), a drain hole 30d for discharging the oil relieved from the first port 40c of the relief valve 40 and supplied through the first relief oil passage 72 is formed in the other end of the regulating valve 30. Therefore, it is possible to prevent the spool 30a from becoming difficult (or unable) to slide after the spool stick (close lock) is released.

[0042] Furthermore, according to this embodiment, even if the regulating valve 30 is a mechanical type (not electronically controlled), it can autonomously perform the operation to eliminate spool stick. Therefore, the present invention can be suitably applied to a hydraulic circuit using a mechanical regulating valve 30.

[0043] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the present invention is applied to the hydraulic circuit 1 of a series hybrid vehicle (SHEV), but the present invention can also be applied to hydraulic circuits of hybrid vehicles of different types (for example, a series-parallel hybrid vehicle, a parallel hybrid vehicle, etc.).

[0044] The present invention can also be applied to hydraulic circuits of conventional gasoline engines and automatic transmissions (for example, stepped automatic transmissions (Step AT) and continuously variable transmissions (CVT)).

[0045] Furthermore, the parts to be lubricated (hydraulic pressure supply destinations) of the hydraulic circuit 1 according to the above embodiment are merely examples, and are not limited to the above embodiment and can be changed as desired.

[0046] In the above embodiment, a one-port type oil pump 22 having a single discharge port has been described as an example. However, instead of the one-port type oil pump 22, for example, a two-port type oil pump having two discharge ports may be used. [Explanation of symbols]

[0047] 1 Hydraulic circuit 11 First motor generator 12 Second motor generator 20 Oil pan 21 Oil strainer 22 Oil pump 30 Regulating valve 30a spool 30b Spring (biasing member) 30d discharge hole 40 Relief valve 40a Valve body 40b Spring (biasing member) 40c 1st port 40d 2nd port 50 Oil cooler 60 Bypass valve 70 Suction oil path 71 Line pressure oil passage 72 First relief oil passage 73 Drain oil passage 74 Lubricating oil path 75 Cooling oil path

Claims

1. an oil pump that pressurizes and discharges oil stored in an oil pan; a regulating valve that adjusts the hydraulic pressure of the oil discharged from the oil pump to generate a line pressure; a relief valve having a first port that opens when the line pressure is equal to or higher than a first hydraulic pressure, and a second port that opens to relieve oil when the line pressure is equal to or higher than a second hydraulic pressure that is higher than the first hydraulic pressure, the regulating valve has a spool housed so as to be slidable in the axial direction, and generates line pressure by adjusting the amount of oil to be drained in accordance with the balance between the biasing force of a biasing member acting on the spool in a valve closing direction and the pushing force due to the hydraulic pressure of the oil discharged from the oil pump acting in a valve opening direction, and further configured such that when the hydraulic pressure of the oil relieved from a first port of the relief valve is applied to the spool in the valve opening direction, the pushing force due to the hydraulic pressure is applied to the spool.

2. The relief valve is a valve case in which the first port and the second port are formed along an axial direction; a valve body that is accommodated inside the valve case so as to be slidable in the axial direction, one end of which is connected to a line pressure oil passage, and a pressing force in a valve opening direction is applied to the one end of the valve body by line pressure; a biasing member disposed at the other end of the valve body and applying a biasing force to the valve body in a valve closing direction; 2. The hydraulic circuit according to claim 1, further comprising:

3. The regulating valve is The biasing member is disposed at one end of the spool, and a biasing force of the biasing member is applied to the spool in a valve closing direction, The other end of the spool is connected to the first port of the relief valve, and when the hydraulic pressure of the oil relieved from the first port of the relief valve is applied to the other end, a pushing force due to the hydraulic pressure is applied to the spool in the valve opening direction.

3. The hydraulic circuit according to claim 2.

4. 4. The hydraulic circuit according to claim 3, wherein the regulating valve is formed with a drain hole for discharging the oil relieved from the first port of the relief valve while enabling a pressing force due to hydraulic pressure of the oil relieved from the first port of the relief valve to be applied to the spool.

5. 5. The hydraulic circuit according to claim 4, wherein the regulating valve is a mechanical valve that generates a line pressure in response to only the balance between a pressing force due to the pressure of the oil discharged from the oil pump and the biasing force of the biasing member.

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