This application claims the priority benefit of Japan Application No. 2018-116931, filed on Jun. 20, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The disclosure relates to a hydraulic circuit for supplying lubricating oil or the like.
For example, a hydraulic circuit is known, which is for controlling an automatic transmission mounted on a vehicle by the oil pressure supplied from an oil pump (for example, see Patent Document 1). The automatic transmission disclosed in Patent Document 1 is a belt type continuously variable transmission, and the hydraulic circuit that controls the automatic transmission includes a circuit of an operating system which is composed of pulleys or the like, and a circuit of a lubricating system which supplies oil to various parts that constitute the continuously variable transmission to lubricate and cool them. Here, an example of the conventional hydraulic circuit is shown in
That is,
The lubricating circuit 105 is provided with a main control valve 107, a first lubricating pressure adjusting valve 108, a second lubricating pressure adjusting valve 109, and a relief valve 110. When the pressure (line pressure) of the oil, which is discharged from the rotating oil pump 106 and flows through the oil passages L11 and L12, exceeds a setting value, since one suction port 107a of the main control valve 107 communicates with two discharge ports 107b and 107c, the lubricating oil flows through the oil passages L13 and L14 of the lubricating circuit 105 and is respectively supplied to the lubricating parts 104a and 104b for lubricating and cooling the lubricating parts 104a and 104b.
When the pressure of the lubricating oil flowing through the lubricating circuit 105 becomes larger than the setting value, as shown in
However, since the conventional hydraulic circuit 101 shown in
[Patent Document 1] Japanese Laid-open No. 2015-200369
In view of the above, the disclosure provides a hydraulic circuit (1), including: an oil pump (6); and a main control valve (7) provided in an oil supply circuit (5), which supplies oil discharged from the oil pump (6). The main control valve (7) is configured to open when a line pressure (P) that acts on the main control valve (7) exceeds a first setting value (P1), to allow the oil to flow to the oil supply circuit (5). The main control valve (7) is provided with a relief port (9b) connected to a suction side of the oil pump (6), and when the line pressure (P) that acts on the main control valve (7) exceeds a second setting value (P2) larger than the first setting value (P1), a part of the oil that flows through the oil supply circuit (5) is returned to the suction side of the oil pump (6) from the relief port (9b) of the main control valve (7).
The disclosure provides a hydraulic circuit without a dedicated relief valve to achieve structure simplification and cost reduction.
In view of the above, the disclosure provides a hydraulic circuit (1), including: an oil pump (6); and a main control valve (7) provided in an oil supply circuit (5), which supplies oil discharged from the oil pump (6). The main control valve (7) is configured to open when a line pressure (P) that acts on the main control valve (7) exceeds a first setting value (P1), to allow the oil to flow to the oil supply circuit (5). The main control valve (7) is provided with a relief port (9b) connected to a suction side of the oil pump (6), and when the line pressure (P) that acts on the main control valve (7) exceeds a second setting value (P2) larger than the first setting value (P1), a part of the oil that flows through the oil supply circuit (5) is returned to the suction side of the oil pump (6) from the relief port (9b) of the main control valve (7).
According to the disclosure, since the main control valve has the function of a relief valve, a dedicated relief valve which is necessary for the related art is not required, and it is possible to simplify the structure of the hydraulic circuit and reduce the cost correspondingly. In addition, by providing the relief port in the main control valve, the pressure regulating performance of the hydraulic circuit can be improved, and it is possible to suppress excessive rise of the oil pressure and improve hydraulic vibration.
Then, in the disclosure, the main control valve (7) may be a spool valve, and when a line pressure (P) that acts on an operating pressure port (9a) of the main control valve (7) exceeds the second setting value (P2), a spool (10) may slide to communicate a suction port (9c) and the relief port (9b).
Also, in the disclosure, a flow control valve (8) may be provided in the oil supply circuit (5) on a downstream side of the main control valve (7), and the flow control valve (8) may be configured so that when a line pressure (P) that acts on the flow control valve (8) exceeds a third setting value (P3), a part of the oil that flows through the oil supply circuit (5) is returned to the suction side of the oil pump (6).
Additionally, in the disclosure, the flow control valve (8) may be a spool valve and include a suction port (12b) connected to the oil supply circuit (5), and a return port (12c) connected to the suction side of the oil pump (6). When the line pressure (P) that acts on the flow control valve (8) is under the third setting value (P3), the suction port (12b) may be closed by a spool (13), and when the line pressure (P) exceeds the third setting value (P3), the suction port (12b) and the return port (12c) may communicate with each other by a spool groove (13a) formed on the spool (13).
Furthermore, an orifice (17) may be provided in an oil passage (L7) that branches from the oil supply circuit (5) and is connected to the suction port (12b) of the flow control valve (8).
According to the disclosure, it is possible to omit a dedicated relief valve to simplify the structure of the hydraulic circuit and reduce the cost.
Embodiments of the disclosure will be described below with reference to the accompanying drawings.
First, a basic configuration of a hydraulic circuit according to the disclosure will be described.
The hydraulic circuit 1 according to the present embodiment is for supplying operating oil and lubricating oil to a power transmission device mounted on a vehicle. The hydraulic circuit 1 includes an operating circuit 3 that supplies operating oil for drive control to an operating part 2 such as a friction clutch, a lubricating circuit (hereinafter referred to as “oil supply circuit”) 5 that supplies lubricating oil to a lubricating part 4 of parts such as a friction clutch and a differential gear, an oil pump 6 that is rotationally driven by a part of the power of an engine or the like which is the drive source, a main control valve 7 provided in the lubricating circuit 5, and a flow control valve 8 provided downstream of the main control valve 7 of the lubricating circuit 5.
The main control valve 7 is a spool valve. The main control valve 7 has a configuration that, as shown in detail in
The flow control valve 8 is also a spool valve similar to the main control valve 7. The flow control valve 8 has a configuration that, as shown in detail in
As shown in
In addition, an oil passage L6 extending from the discharge port 9d of the main control valve 7 constitutes a part of the oil supply circuit 5 and is connected to the lubricating part 4, and an oil passage L7 branching from the oil passage L6 is connected to the suction port 12b of the flow control valve 8. Then, an orifice 17 for controlling the flow rate of the oil flowing therethrough is provided in the middle of the oil passage L7. In addition, an oil passage L8 branches from the oil passage L6, and the oil passage L8 is connected to the operating pressure port 12a of the flow control valve 8. The oil passage L8 is also provided with an orifice 18.
Moreover, one end of an oil passage L9 is connected to the return port 12c of the flow control valve 8, and the other end of the oil passage L9 is connected to the oil passage L5 connected to the suction side of the oil pump 6.
Next, an operation of the hydraulic circuit 1 configured as described above will be described.
In the state where the oil pump 6 is stopped, as shown in
When the oil pump 6 is rotationally driven at a relatively low load, the pressure of the oil discharged from the oil pump 6 is relatively low. At this time, if the line pressure P acting on the operating pressure port 9a of the main control valve 7 via the oil passages L2 and L3 exceeds a first setting value P1 (P>P1), as shown in
Then, when the line pressure P acting on the operating pressure port 9a of the main control valve 7 exceeds P2 (second setting value) which is larger than P1 (P>P2>P1), the spool 10 of the main control valve 7 slides further to the right against the urging force of the spring 11, as shown in
In the flow control valve 8, the pressure of the oil that flows through the oil passage L6 acts on the operating pressure port 12a via the oil passage L8 and the orifice 18 as the line pressure P, but when the line pressure P is under P3 (third setting value) (P≤P3), the spool 13 of the flow control valve 8 blocks the oil passage L7, and therefore the return of the oil from the oil passage L9 to the oil passage L5 on the suction side of the oil pump 6 is blocked. Thus, all the oil that flows through the oil passage L6 of the oil supply circuit 5 is supplied to the lubricating part 4, and the lubricating part 4 is lubricated and cooled by a necessary and sufficient amount of oil. The oil pressure P3 here is an oil pressure set separately from the oil pressure P1 and the oil pressure P2, and the relationship between P1, P2, and P3 may be changed as desired by setting the main control valve 7 and the flow control valve 8.
Furthermore, when the line pressure P that acts on the operating pressure port 12a of the flow control valve 8 from the oil passage L8 exceeds the third setting value P3 (P>P3), as shown in
As described above, when the line pressure P that acts on the operating pressure port 12a of the flow control valve 8 exceeds the third setting value P3 (P>P3), a part of the oil that flows through the oil passage L6 of the oil supply circuit 5 bypasses the lubricating part 4 and is returned from the oil passage L7 to the oil passage L5 on the suction side of the oil pump 6 through the flow control valve 8 and the oil passage L9. Thus, the flow rate of the oil supplied to the lubricating part 4 is suppressed to be small. Therefore, the frictional resistance of the oil in the lubricating part 4 is suppressed to be low, which improves the fuel efficiency of the vehicle. In addition, since the extra oil that flows through the oil passage L6 of the oil supply circuit 5 is returned from the return port 12c of the flow control valve 8 to the oil passage L5 on the suction side of the oil pump 6 via the oil passage L9, the pump efficiency of the oil pump 6 is increased and the fuel efficiency of the vehicle is further improved. Further, in the present embodiment, since the oil passage L7 that branches from the oil passage L6 and is connected to the suction port 12b of the flow control valve 8 is provided with the orifice 17, the amount of oil flowing through the oil passage L7 is limited by the orifice 17 and the flow rate of the oil supplied from the oil passage L6 to the lubricating part 4 is larger than the flow rate of the oil returned from the oil passage L9 to the oil passage L5 on the suction side of the oil pump 6, and a necessary and sufficient amount of oil can be supplied to the lubricating part 4.
As described above, in the hydraulic circuit 1 of the disclosure, the main control valve 7 has the function of a relief valve. Therefore, a dedicated relief valve which is necessary for the related art is not required, and correspondingly the disclosure can simplify the structure of the hydraulic circuit 1 and reduce the cost.
Nevertheless, the disclosure is not limited to the embodiments described above, and various modifications may be made within the scope of the technical concept described in the claims, specification, and drawings.
Number | Date | Country | Kind |
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2018-116931 | Jun 2018 | JP | national |