JP2017160996A - Hydraulic circuit for hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a preferable restriction against variation in pressure when a value relation of driving pressures at a device is changed over at a hydraulic circuit for alternatively supplying second hydraulic pressure required for controlling the device by a second pump while supplying a first hydraulic pressure required in minimum for operating the device by a first pump.SOLUTION: A first pulley and a first pump 10 are connected by a first line 1 provided with a first check valve 9. A second pulley and the first pump 10 are connected by a second line 2 provided with a second check valve 11. A first relief line 7 related to the first pulley and a second relief line 8 related to the second pulley are connected in series and crossed to each other in respect to a first relief valve 30 and a second relief valve 40. In addition, pilot pressures for the first relief valve 30 and the second relief valve 40 are applied as a discharging pressure of the first pump 10 and at the same time a feed-back pressure is applied as a first pulley driving pressure P1 or a second pulley driving pressure P2. In addition, a second pump 20 is arranged between the first line 1 and the second line 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic circuit for a hydraulic device, and more specifically, controls a device by a second pump while constantly supplying a first hydraulic pressure necessary for the operation of the device by a first pump to a pair of hydraulic devices. The present invention relates to a hydraulic circuit for hydraulic equipment that alternately supplies a second hydraulic pressure of a certain amount of oil required for the operation.

  2. Description of the Related Art Conventionally, an engine-driven pump that is always driven by an engine and an electric pump that is driven by a motor are provided. The engine-driven pump constantly supplies the hydraulic pressure necessary to sandwich the belt, whereas the electric pump has a first pulley. 2. Description of the Related Art A hydraulic circuit for a belt type continuously variable transmission (CVT) that supplies oil pressure necessary for gear ratio control by reversibly moving oil between the first pulley and a second pulley (for example, patents) See reference 1.)

  In the oil supply system from the engine drive pump to the first pulley and the second pulley, a pump regulator is connected to the outlet of the engine drive pump, and the pump regulator is connected to the primary pressure line. The primary pressure line is connected to the input port of the switching valve, and the first pulley secondary pressure line and the second pulley secondary pressure line are connected to the two output ports of the switching valve, respectively. The first pulley secondary pressure line is connected to the first pulley oil chamber, and the second pulley secondary pressure line is connected to the second pulley oil chamber.

  The switching valve has feedback ports at both shaft ends in addition to the input port and the two output ports. A first pulley feedback line related to the first pulley driving pressure branched from each pulley secondary pressure line and a second pulley feedback line related to the second pulley driving pressure are connected to each feedback port.

  Therefore, when a pressure difference is generated between the first pulley driving pressure and the second pulley driving pressure, the valve body of the switching valve moves in the axial direction, whereby the pulley with the lower pulley driving pressure (low pressure pulley) is moved. And the primary pressure line communicate with each other, while the pulley having the higher pulley driving pressure (high pressure pulley) and the primary pressure line are cut off. In other words, the CVT hydraulic circuit is configured such that oil is always supplied to the low-pressure pulley by the switching valve.

  By the way, the valve body of the switching valve has two large-diameter portions, and each large-diameter portion opens and closes two output ports separately. That is, while one large diameter portion opens one output port opening, the other large diameter portion closes another output port opening. Moreover, the circumferential recessed part between large diameter parts becomes an oil path which connects a primary pressure line and a 1st pulley secondary pressure line, or a primary pressure line and a 2nd pulley secondary pressure line separately.

JP 2005-226730 A

  Patent Document 1 discloses that the distance X between the output ports of the switching valve is designed to be equal to the distance Y between the large diameter portions (see, for example, [0035]).

  However, due to the accuracy of manufacturing machines, dimensional tolerances of individual parts, assembly accuracy, etc., it is actually impossible to manufacture a switching valve so that the distance between output ports X and the distance between large diameter parts Y are equal. It is believed that there is.

  Therefore, in the neutral state of the switching valve, the large diameter portion does not completely close the output port opening (X <Y), or the large diameter portion overlaps the output port opening. One of the relations (X> Y) is considered to be taken.

  In the case of the underlap position relationship, there is a valve stroke position where the two pulleys and the primary pressure line communicate with each other in the process of moving the valve body. Therefore, oil leaks from the output port that should be closed, and the hydraulic pressure required for the gear ratio control of the pulley cannot be supplied. As a result, the pulley gear ratio control cannot be performed.

  On the other hand, in the case of the overlap position relationship, there is a valve stroke position where the primary pressure line does not communicate with any pulley in the process of moving the valve body. For this reason, there is a problem in that it is impossible to supply the hydraulic pressure required for the friction transmission of the CVT.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to always apply the first hydraulic pressure that is the minimum required for the operation of the device by the first pump to the hydraulic device that operates in a pair. While supplying, the second pump supplies the second oil pressure of a constant oil amount necessary for controlling the device alternately without excess and deficiency, and when the magnitude of the drive pressure of the hydraulic device is switched, the fluctuation of the drive pressure is preferably It is an object of the present invention to provide a hydraulic circuit for a hydraulic device that can be controlled and thereby enable smooth transmission gear ratio control of the hydraulic device without causing a discontinuous point of driving pressure.

  In order to achieve the above object, a hydraulic circuit for a hydraulic device according to the present invention includes a first hydraulic device (Pu1, Pu2) operating in a pair and a minimum for driving the first and second hydraulic devices. A first pump (10) that constantly supplies the first hydraulic pressure (PL pressure) that is necessary and a second pump (20) that alternately supplies the second hydraulic pressure for control to the first and second hydraulic devices. A first line (1) for connecting the first pump (10) and the first hydraulic device (Pu1), and a second line for connecting the first pump (10) and the second hydraulic device (Pu2). A line (2), a first relief line (7) branched from the first line (1), a second relief line (8) branched from the second line (2), feedback pressure and pilot pressure, The first and second reliefs by balancing the forces of The first relief valve (30) and the second relief valve (40) that open and close the in-lines (7, 8), respectively, and the discharge pressure of the first pump (10) by the balance between the feedback pressure and the pilot pressure. A hydraulic circuit for a hydraulic device having a pressure regulating valve (50) for regulating the first hydraulic pressure (PL pressure), wherein the first and second lines (1, 2) are connected to the first pump (10). A first check valve (9) and a second check valve (11) for preventing the oil from flowing into the first and second check valves (11), respectively, and the first and second relief lines (7, 8) are the first and second check valves, respectively. The first and second relief valves (30, 40) are connected in series and cross to the relief valve (30, 40), and the first and second relief valves (30, 40) serve as feedback pressures of the first drive pressure (Pu1). P1) or the second hydraulic device ( Any one of with separate capture of the second driving pressure u2) (P2), characterized in that the separate loading a delivery pressure of the first pump (10) (PL pressure) as the pilot pressure.

  In the above configuration, the first hydraulic device (Pu1) and the second hydraulic device (Pu2) are connected to the first pump (10) via the first check valve (9) and the second check valve (11), respectively. Has been. As a result, the first hydraulic device (Pu1) and the second hydraulic device (Pu2) are connected via the check valves (9, 11) when the first and second drive pressures (P1, P2) are lower than the PL pressure. Thus, the oil is supplied, so that the first and second drive pressures (P1, P2) do not fall below the PL pressure.

  Further, the first relief line (7) and the second relief line (8) are connected in series and intersecting with the first and second relief valves (30, 40). Thereby, in the first and second relief valves (30, 40), the valve opening positions (valve opening order) of the first and second relief lines (7, 8) can be made different from each other.

  The second pump (20) alternately supplies hydraulic pressure to the first hydraulic device (Pu1) and the second hydraulic device (Pu2). Further, the first and second relief valves (30, 40) are configured to separately take in one of the first driving pressure (P1) and the second driving pressure (P2) as the feedback pressure. ing. Thereby, it becomes possible to attach a magnitude relationship to each feedback pressure acting on the first and second relief valves (30, 40). As a result, in the first and second relief valves (30, 40), the valve positions of the first and second relief lines (7, 8) are made different (for example, one is fully open and the other is fully closed). ) Is possible. Thereby, when the first and second drive pressures (P1, P2) exceed the PL pressure, the relief line related to the hydraulic device with the lower drive pressure is more than the relief line related to the hydraulic device with the higher drive pressure. It is always possible to open first and relieve the excess pressure that exceeds it. In other words, it is possible to configure so that the oil related to the excess pressure is always drained from the hydraulic device having the lower drive pressure.

  That is, according to the above configuration, when the drive pressures (P1, P2) of the first and second hydraulic devices (Pu1, Pu2) are lower than the PL pressure, the first check valve (9) or the second reverse valve is always used. The stop valve (11) is opened and oil is supplied to the hydraulic equipment with insufficient pressure. On the other hand, when each driving pressure (P1, P2) exceeds the PL pressure, the relief line related to the hydraulic device having a low driving pressure is always opened first, and the oil related to the excess pressure is drained. As a result, the first and second hydraulic devices (Pu1, Pu2) can be smoothly operated without causing discontinuities in the driving pressure.

  The second feature of the hydraulic circuit for hydraulic equipment according to the present invention is that the first and second relief valves (30, 40) are configured to open in order as the feedback pressure increases, It has communication oil paths (31a, 31c, 41a, 41c).

  In the above configuration, the first relief line (7) and the second relief line (8) can be connected to the two communication oil passages. Thereby, according to the magnitude | size of a feedback pressure (driving pressure), it becomes possible to open a 1st relief line (7) and a 2nd relief line (8) in order.

  A third feature of the hydraulic circuit for a hydraulic device according to the present invention is that the relief valve having a higher feedback pressure while the oil is supplied to the first and second hydraulic devices (Pu1, Pu2) The relief valve having the lower feedback pressure is in a state (A) in which all of the two communication oil passages are closed.

  In the above configuration, while the oil is supplied to the hydraulic equipment, the relief valve with the higher feedback pressure (driving pressure) is fully open, and the relief valve with the lower feedback pressure (driving pressure) is fully closed. Therefore, when the lower drive pressure exceeds the PL pressure, the feedback pressure increases and the relief line with the lower drive pressure opens. In other words, when the lower driving pressure exceeds the PL pressure while the oil is being supplied to the pulley, it is possible to drain the oil related to the excess pressure from the relief line related to the hydraulic equipment having the lower driving pressure. .

  According to a fourth aspect of the hydraulic circuit for a hydraulic device according to the present invention, the relief valve having a higher feedback pressure while the oil is flowing back from the first and second hydraulic devices (Pu1, Pu2) In contrast to the state (E) in which all the two communication oil passages are open, the relief valve having the lower feedback pressure is in a state in which only the communication oil passage relating to the hydraulic device having the lower drive pressure is open ( B).

  In the above configuration, the relief valve with the higher feedback pressure (driving pressure) is fully opened while the relief valve with the lower feedback pressure (driving pressure) is driven with the lower one while oil flows backward from the hydraulic equipment. Only the communication oil passage related to the pressure is open. Therefore, when the lower driving pressure exceeds the PL pressure, the oil related to the excess pressure is drained from the relief line related to the hydraulic equipment having the lower driving pressure.

  A fifth feature of the hydraulic circuit for hydraulic equipment according to the present invention is that a linear solenoid (60) for supplying a pilot pressure related to the first hydraulic pressure (PL pressure) to the pressure regulating valve (50) is provided. The original pressure of the linear solenoid (60) is the discharge pressure of the first pump (10).

  In the above configuration, the pressure regulating valve (50) regulates the discharge pressure of the first pump (10) to the PL pressure based on the pilot pressure, and the pilot pressure uses the discharge pressure of the first pump (10) as the original pressure. As produced by the linear solenoid (60). That is, the discharge pressure of the first pump (10) can be adjusted to a desired pressure (PL pressure) by the linear solenoid (60).

  A sixth feature of the hydraulic circuit for a hydraulic device according to the present invention is that the first and second hydraulic devices (Pu1, Pu2) are a pair of pulley mechanisms.

  In the above configuration, the first pump (10) always maintains the driving pressure at a minimum PL pressure for friction transmission in the pulley with the lower driving pressure, and the second driving pulley in the pulley with the higher driving pressure. The hydraulic pressure necessary for pulley gear ratio control is supplied without excess or deficiency by the pump (20).

  According to the hydraulic circuit for hydraulic equipment of the present invention, the first hydraulic pressure (PL pressure) necessary for the operation of the equipment is always supplied to the hydraulic equipment (Pu1, Pu2) operating in a pair by the first pump (10). However, the second pump (20) can alternately supply a constant amount of the second hydraulic pressure necessary for the gear ratio control of the device without excess or deficiency, and the drive pressure (P1, P2) of the hydraulic device can be supplied. When the magnitude relationship is switched, fluctuations in driving pressure are suitably suppressed. As a result, it is possible to smoothly control the gear ratio of the hydraulic device without causing a discontinuous point of the driving pressure.

  Further, the unnecessary driving pressure related to the pressure fluctuation is suitably suppressed, so that the discharge pressure of each pump is lowered, thereby reducing the pump driving power. As a result, energy loss can be reduced.

It is explanatory drawing which simplified and showed the structure of the hydraulic circuit which concerns on this embodiment. It is principal part sectional explanatory drawing which shows the 1st relief valve and 2nd relief valve which concern on this embodiment. It is explanatory drawing which shows the valve position of the 1st relief valve which concerns on this embodiment. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1> P2 and Q1 <0 and Q2> 0. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1> P2 and Q1 <0 and Q2 <0. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1 <P2 and Q1> 0 and Q2 <0. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1 <P2, Q1 <0, and Q2 <0. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1 = P2 and Q1> 0 and Q2> 0. It is explanatory drawing which shows operation | movement of the hydraulic circuit under the conditions of P1 = P2 and Q1 <0 and Q2 <0. It is explanatory drawing which shows the correlation between the magnitude relationship of the pulley drive pressure in this hydraulic circuit, the direction of oil flow, the valve position of the relief valve, and the open / close state of the check valve. It is a graph which shows the operation result (pulley drive pressure, pulley oil flow, relief valve position, oil flow through check valve) of the hydraulic circuit according to the present embodiment. It is explanatory drawing which shows the hydraulic circuit which concerns on other embodiment of this invention. It is explanatory drawing which shows the hydraulic circuit which concerns on other embodiment of this invention. It is explanatory drawing which shows the hydraulic circuit which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing a simplified configuration of a hydraulic circuit 100 according to the present embodiment.
The hydraulic circuit 100 includes a first pulley Pu1 (not shown) and a second pulley Pu2 of a belt-type continuously variable transmission (hereinafter also referred to as “CVT”) using the first pump 10 and the second pump 20 together. It is a hydraulic circuit for CVT that supplies oil to (not shown). The first pump 10 supplies a minimum pressure required for friction transmission of the CVT (hereinafter also referred to as “PL pressure” or “first hydraulic pressure”), and the second pump 20 controls the transmission ratio of the CVT. The required constant amount of pressure (hereinafter also referred to as “transmission specific pressure” or “second hydraulic pressure”) is alternately supplied.

  In the hydraulic circuit 100, the pulley driving pressure of the pulley having the lower pulley driving pressure (hereinafter also referred to as “low pressure pulley”) is always maintained at the PL pressure by the first pump 10 and the driving pressure is higher. The pulley drive pressure of the pulley (hereinafter also referred to as “high pressure pulley”) is applied with a gear ratio pressure by the second pump 20 in addition to the PL pressure by the first pump 10. Accordingly, none of the first pulley driving pressure P1 and the second pulley driving pressure P2 is lower than the PL pressure. In particular, when the pulley drive pressure exceeds the PL pressure, the oil related to the excess pressure is configured to be drained from the low-pressure pulley. As described above, in the hydraulic circuit 100, the reference pressure of the pulley driving pressure is set as the PL pressure, and the low pressure pulley is always maintained at the PL pressure by the first pump 10, while the high pressure pulley is controlled by the second pump 20 for speed ratio control. Necessary oil is supplied without excess or deficiency. As a result, smooth pulley gear ratio control without causing discontinuities in driving pressure is possible.

  As the configuration of the hydraulic circuit 100, the first pump 10 that is always driven by the engine E, the second pump 20 that is driven by the motor M, and the first pulley driving pressure P1 or the second pulley driving pressure P2 has a PL pressure. The first relief valve 30 and the second relief valve 40 that drain oil from the low pressure pulley when exceeding, the first line 1 that connects the first pump 10 and the first pulley Pu1, the first pump 10 and the second pulley Pu2. A third line 3 that acts as a pilot pressure on the first relief valve 30, a fourth line 4 that acts on the second relief valve 40 as a pilot pressure, The fifth line 5 that acts on the first relief valve 30 using the first pulley driving pressure P1 as a feedback pressure, and the second relief valve 40 A second line 6 that acts as a feedback pressure, and a first relief line 7 that drains oil returning from the first pulley Pu1 to the first pump 10 side; The second relief line 8 that drains the oil returning from the pulley Pu2 to the first pump 10 side, and the oil returning from the first pulley Pu1 flows into the first pump 10 side through the first line 1. A first check valve 9 for blocking, a second check valve 11 for blocking oil returning from the second pulley Pu2 from flowing into the first pump 10 through the second line 2, and a first pump PL regulator valve 50 that regulates the pressure of oil discharged from the pressure to PL pressure, and a PL control valve that supplies pilot pressure to the PL regulator valve 50 It is configured by including a 60. Hereinafter, each configuration will be described in more detail.

  The first relief valve 30 and the second relief valve 40 are pressure control valves that control the feedback pressure to be equal to the pilot pressure by balancing the force between the feedback pressure and the pilot pressure. Pulley drive pressures P1 and P2 are taken in via the fifth line 5 or the sixth line 6 as feedback pressure, respectively, and PL pressure is taken in via the third line 3 or the fourth line 4 as pilot pressure.

  Moreover, the 1st relief valve 30 and the 2nd relief valve 40 have six ports on the exterior, and comprise the 2 system communication oil path (relief flow path) from which a valve opening position differs inside. One is an oil passage communicating the second port P2 and the sixth port P6, and the other is an oil passage communicating the third port P3 and the fifth port P5. Therefore, when the pulley drive pressures P1 and P2 exceed the PL pressure, these oil passages communicate with each other, thereby releasing excess pressure exceeding the PL pressure. Although details will be described later with reference to FIG. 2, the valve positions indicated by A to E in the figure are provided.

  The 1st relief line 7 is a relief line for draining the oil which concerns on the excess pressure exceeding PL pressure about the 1st pulley drive pressure P1 to the 1st pump 10 side. The first relief valve 30 and the second relief valve 40 are connected in series and connected to the second relief line 8 so as to intersect (cross). That is, the first relief line 7 is connected to the second port P2 and the sixth port P6 in the first relief valve 30, whereas it is connected to the third port P3 and the fifth port P5 in the second relief valve 40. Only when both the relief valves 30 and 40 are opened, the first relief line 7 can drain the oil returning from the first pulley Pu1 to the first pump 10 side.

  On the other hand, the 2nd relief line 8 is a relief line for draining the oil which concerns on the excess pressure which exceeds PL pressure about the 2nd pulley drive pressure P2 to the 1st pump 10 side. The first relief valve 30 and the second relief valve 40 are connected in series, and are connected to the first relief line 7 so as to cross (cross). That is, the second relief line 8 is connected to the second port P2 and the sixth port P6 in the second relief valve 40, whereas it is connected to the third port P3 and the fifth port P5 in the first relief valve 30. Only when both the relief valves 30 and 40 are opened, the second relief line 8 can drain the oil returning from the second pulley Pu2 to the first pump 10 side.

  The PL regulator valve 50 takes in the discharge pressure of the first pump 10 as a source pressure and a feedback pressure, and adjusts the discharge pressure of the first pump 10 to the PL pressure by balancing the force of the feedback pressure, the pilot pressure, and the spring load. It is a pressure regulating valve. The pilot pressure is supplied by the PL control valve 60.

  The pilot-side piston area of the PL regulator valve 50 is set to be larger than the feedback-side piston area.

  The PL control valve 60 regulates by a linear solenoid using the discharge pressure of the first pump 10 as an original pressure, and outputs the output value to the PL regulator valve 50 as a pilot pressure.

  The first pump 10 is a positive displacement pump, for example, an internal gear pump. The PL pressure required for the frictional transmission of the CVT is supplied to the first pulley Pu1 and the second pulley Pu2. Hereinafter, a hydraulic circuit surrounded by a dotted line including the first pump 10, the PL regulator valve 50, and the PL control valve 60 will be referred to as a low pressure circuit 110.

  The first pulley Pu1 or the second pulley Pu2 is connected to the low pressure circuit 110 via the first line 1 and the first check valve 9 or the second line 2 and the second check valve 11. Therefore, the first pulley driving pressure P1 and the second pulley driving pressure P2 do not fall below the PL pressure.

  The second pump 20 is a reciprocating pump that alternately moves oil from one pulley to the other pulley. The hydraulic pressure necessary for gear ratio control is supplied to the high-pressure pulley. Since the excess pressure exceeding the PL pressure is always drained from the low-pressure pulley, the oil that is moved between the pulleys by the second pump 20 passes through the first relief line 7 or the second relief line 8. It is not drained to the low voltage circuit 110 via

  FIG. 2 is an explanatory cross-sectional view of a main part showing the first relief valve 30 and the second relief valve 40 according to the present embodiment. Since the internal structures of the first relief valve 30 and the second relief valve 40 are the same, the second relief valve 40 will be omitted. For convenience of explanation, the oil passages connected to each port (third line 3, fourth line 4, fifth line 5, sixth line 6, first relief line 7, second relief line 8) are also described. It is also illustrated.

  Also, in each internal structure of the first relief valve 30 and the second relief valve 40, similar configurations are given the same number in the first place, for example, valve bodies 31 and 41, and each valve in the tenth place. We will add numbers to distinguish them from each other.

  The first relief valve 30 includes a valve body 31, a body 32, and a spring 33. The valve body 31 has, in order from the left in the axial direction, a first circumferential recess 31a for communicating the third port P3 and the fifth port P5, and a circumferential projection 31b for narrowing or closing the third port P3. A second circumferential recess 31c for communicating the second port P2 and the sixth port P6 and a hollow cylindrical portion 31d for narrowing the second port P2 and accommodating the spring 13 are formed.

  A first port P1 for introducing the PL pressure from the low-pressure circuit 110, a second port P2 for introducing the oil returning from the first pulley Pu1, and the second relief, in order from the right side in the axial direction, to the body 32. A sixth port P6 for transferring to the third port P3 of the valve 40 and a third port P3 for introducing oil returning from the second pulley Pu2 via the sixth port P6 of the second relief valve 40 A fifth port P5 for transferring oil returning from the second pulley Pu2 to the low pressure circuit 110, and a fourth port P4 for introducing feedback pressure (first pulley driving pressure P1). ing. Furthermore, a left end portion 32a against which the valve body 31 abuts and a right end portion 32b against which the spring 33 abuts are formed.

  In the second relief valve 40, the second relief line 8 is connected to the second port P2 and the sixth port P6, and the first relief line 7 is connected to the third port P3 and the fifth port P5.

  FIG. 3 is an explanatory diagram showing the valve position of the first relief valve 30 according to the present embodiment. Each valve position indicated by A to E corresponds to each valve position shown in FIG. Further, a portion surrounded by a circle indicates a relief portion.

  The valve position A is a state in which the valve body 31 is in contact with the left end portion 32b. In this state, the second port P2 related to the first relief line 7 is closed by the hollow cylindrical portion 31d. Further, the third port P3 related to the second relief line 8 is closed by the circumferential convex portion 31b.

  The valve position B is a state immediately before the second port P2 is opened. In this state, the third port P3 is closed by the circumferential convex portion 31b.

  The valve position C is a state in which the valve body 31 moves further to the right in the axial direction from B and the second port P2 is completely opened. In this state, the second port P2 and the sixth port P6 are in communication. Further, the third port P3 is closed by the circumferential convex portion 31b.

  The valve position D is a state immediately before the valve body 31 moves further to the right in the axial direction from C and the third port P3 is opened.

  The valve position E is a state in which the valve body 31 moves further to the right in the axial direction from D and the third port P3 is completely opened.

  As described above, when the feedback pressure rises, the valve body 31 moves to the right in the axial direction, first the second port P2 related to the first relief line 7 is opened, and then the third port P3 related to the second relief line 8. Opens.

  As described above, the first relief valve 30 opens the first relief line 7 related to the first pulley driving pressure P1, which is the subject of pressure regulation, first, and the second relief related to the second pulley driving pressure P2 is delayed. Open the line.

  4 to 9 are explanatory diagrams showing the operation of the hydraulic circuit 100 according to the present embodiment. In addition, the solid line arrows in FIGS. 4 to 9 indicate the flow of oil related to the low pressure pulley having the lower pulley driving pressure. The dotted arrow indicates the flow of oil related to the high-pressure pulley having the higher pulley driving pressure. Further, a portion surrounded by a circle indicates a relief portion. Q1 or Q2 indicates the flow rate of the oil supplied to each pulley or the oil returning from each pulley. The sign is positive when oil is supplied and negative when oil returns.

FIG. 4 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1> P2 and Q1 <0 and Q2> 0.
Since P1> P2, the first pulley Pu1 is a high pressure pulley and the second pulley Pu2 is a low pressure pulley. Further, since Q1 <0, the oil is flowing back from the first pulley Pu. Therefore, the first pulley drive pressure P1 is higher than the PL pressure. The first check valve 9 is in a closed state. As a result, the feedback pressure of the first relief valve 30 is higher than the PL pressure. As a result, the first relief valve 30 is stabilized at the valve position E as shown in FIG.

  On the other hand, the oil is supplied to the second pulley Pu2 from Q2> 0. Therefore, the second pulley driving pressure P2 is lower than the PL pressure. The second check valve 11 is in an open state. As a result, the feedback pressure of the second relief valve 40 is lower than the PL pressure. As a result, the second relief valve 40 is stabilized at the valve position A as shown in FIG.

  Accordingly, the oil returning from the first pulley Pu1 passes through the first relief line 7, the second port P2 and the sixth port P6 of the first relief valve 30, and again passes through the first relief line 7 to the second relief valve 40. It flows into the third port P3. However, since the third port P3 of the second relief valve 40 is closed, the flow rate Q1 of the oil returning from the first pulley Pu1 is stabilized at zero. That is, the oil returning from the high pressure pulley is not returned to the low pressure circuit 110.

FIG. 5 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1> P2 and Q1 <0 and Q2 <0.
From Q2 <0, the oil is flowing back from the second pulley Pu2. That is, this corresponds to the case where the second pulley drive pressure P2 temporarily exceeds the PL pressure in the pressure state shown in FIG. Therefore, the second check valve 11 is closed. As a result, the feedback pressure of the first relief valve 30 is temporarily higher than the PL pressure. As a result, the valve position of the second relief valve 40 moves from A to B as shown in FIG. On the other hand, the valve position of the first relief valve 30 remains E.

  As the valve position of the second relief valve 40 moves from A to B, the second port P2 of the second relief valve 40 begins to open. As a result, the oil returning from the second pulley Pu2 is relieved from the opening of the second port P2, while the sixth port P6, the second relief line 8, the third port P3 and the fifth port of the first relief valve 30. P5 returns to the low voltage circuit 110 through the second relief line 8 again. The oil returning from the first pulley Pu1 is not returned to the low pressure circuit 110 because the third port P3 of the second relief valve 40 is closed. That is, the oil returning from the low pressure pulley is returned to the low pressure circuit 110, whereas the oil returning from the high pressure pulley is not returned to the low pressure circuit 110.

FIG. 6 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1 <P2 and Q1> 0 and Q2 <0.
This case corresponds to the case where the magnitude relation or the flowing direction is reversed for each pulley driving pressure P1, P2 or each flow rate Q1, Q2 in FIG. Accordingly, the first relief valve 30 is stabilized at the valve position A. On the other hand, the second relief valve 40 is stabilized at the valve position E.

  Accordingly, the oil returning from the second pulley Pu2 passes through the second relief line 8, the second port P2 and the sixth port P6 of the second relief valve 40, and again passes through the second relief line 8 to the first relief valve 30. It flows into the third port P3. However, since the third port P3 of the first relief valve 30 is closed, the flow rate Q2 of the oil returning from the second pulley Pu2 is stabilized at zero. That is, the oil returning from the high pressure pulley is not returned to the low pressure circuit 110.

FIG. 7 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1 <P2, Q1 <0, and Q2 <0.
In this case, this corresponds to the case where the magnitude relations of the pulley driving pressures P1 and P2 in FIG. 5 are reversed. Accordingly, the first relief valve 30 is stabilized at the valve position B. On the other hand, the second relief valve 40 is stabilized at the valve position E.

  Accordingly, the oil returning from the first pulley Pu1 is relieved from the opening of the second port P2 of the first relief valve 30, while the sixth port P6, the first relief line 7, and the third port of the second relief valve 40 are relieved. P3 and the fifth port P5 are returned to the low voltage circuit 110 through the first relief line 7 again. The oil returning from the second pulley Pu2 is not returned to the low pressure circuit 110 because the third port P3 of the first relief valve 30 is closed. That is, the oil returning from the low pressure pulley is returned to the low pressure circuit 110, whereas the oil returning from the high pressure pulley is not returned to the low pressure circuit 110.

FIG. 8 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1 = P2, Q1> 0 and Q2> 0.
In this state, the oil is supplied to the first pulley Pu1 and the second pulley Pu2 from Q1> 0 and Q2> 0. Therefore, the first pulley driving pressure P1 and the second pulley driving pressure P2 are in a state lower than the PL pressure. Further, the first check valve 9 and the second check valve 11 are open. As a result, the feedback pressure is lower than the PL pressure in the first relief valve 30 and the second relief valve 40. As a result, as shown in FIG. 4, both the first relief valve 30 and the second relief valve 40 are stabilized at the valve position A.

FIG. 9 is an explanatory diagram showing the operation of the hydraulic circuit 100 under the conditions of P1 = P2, Q1 <0, and Q2 <0.
From Q1 <0 and Q2 <0, the oil is flowing back from the first pulley Pu1 and the second pulley Pu2. That is, this corresponds to the state when the magnitude relationship of the pulley driving pressure in FIG. 7 is switched from P1 <P2 to P2> P1.

  Here, it is assumed that the oil is moved from the second pulley Pu2 to the first pulley Pu1 by the second pump 20 in the state shown in FIG. The first check valve 9 is closed from Q1 <0. As a result, the feedback pressure of the first relief valve 30 increases. As a result, as shown in FIG. 9, the valve body 31 moves to the right in the axial direction, whereby the valve position of the first relief valve 30 moves from B to D.

  On the other hand, when the oil is supplied from the second pulley Pu2 to the first pulley Pu1, the feedback pressure of the second relief valve 40 decreases. As a result, as shown in FIG. 9, the valve body 41 moves to the left in the axial direction, whereby the valve position of the second relief valve 40 moves from E to D. As a result, both the first relief valve 30 and the second relief valve 40 are stabilized at the valve position D.

  As a result, the oil returning from the first pulley Pu1 passes through the first relief line 7, the second port P2 and the sixth port P6 of the first relief valve 30, and again through the first relief line 7, and then the second relief valve 40. Into the third port P3. The oil flowing into the third port P3 is returned to the low-pressure circuit 110 through the fifth port P5 and the first relief line 7 again while being relieved from the opening of the third port P3.

  The oil returning from the second pulley Pu2 passes through the second relief line 8, the second port P2 and the sixth port P6 of the second relief valve 40, and again passes through the second relief line 8 to the first relief valve 30. It flows into the third port P3. The oil flowing into the third port P3 is returned to the low-pressure circuit 110 through the fifth port P5 and the second relief line 8 again while being relieved from the opening of the third port P3.

  As described above, in the hydraulic circuit 100, the oil returning from the low pressure pulley is returned to the low pressure circuit 110, whereas the oil returning from the high pressure pulley is not returned to the low pressure circuit 110. This indicates that the driving pressure of the low-pressure pulley is always maintained at the PL pressure by the low-pressure circuit 110, and the oil that causes the second pump 20 to alternately move between the pulleys is supplied to the high-pressure pulley without excess or deficiency. Yes.

  FIG. 10 is an explanatory diagram showing the correlation among the magnitude relationship of the pulley drive pressure in the hydraulic circuit 100, the direction of oil flow, the valve position of the relief valve, and the open / closed state of the check valve. Case 1 to case 6 correspond to FIGS. 4 to 9, respectively.

  The magnitude relationship of the pulley driving pressure according to the hydraulic circuit 100 is roughly divided into three cases: P1> P2, P2> P1, and P1 = P2.

  The direction in which oil flows is roughly divided into two directions, a direction to supply to the pulley and a direction to return from the pulley. Therefore, there are 12 cases in which the oil flows in consideration of the magnitude relationship of the pulley driving pressure.

  However, in the hydraulic circuit 100, it is impossible to supply oil to the high pressure pulley. This is because the pulley driving pressure of the high-pressure pulley is always higher than the discharge pressure (= PL pressure) of the first pump 10. Accordingly, two cases of P1> P2 and Q1> 0 and two cases of P2> P1 and Q2> 0 are excluded from twelve cases.

  Also, when the pulley drive pressures are equal (P1 = P2), when oil is supplied to one pulley and at the same time the oil returns from the other pulley (Q1> 0 and Q2 <0, Q1 <0 and Q2> 0) can only occur excessively. This is because when Q2 <0, the second check valve 11 is closed. This is because when the second check valve 11 is closed, P1 <P2. Similarly, if Q1 <0, P1> P2 immediately. Therefore, these two cases are also excluded from the 12 cases. As a result, there are six directions in which the oil flows in consideration of the magnitude relationship of the pulley driving pressure as shown in case 1 to case 6 in FIG.

  Regarding the valve positions of the first relief valve 30 and the second relief valve 40, the relief valve related to the high pressure pulley is stabilized at the valve position E as shown in Case 1 to Case 4. That is, the relief valve related to the high pressure pulley is always fully open.

  On the other hand, the relief valve related to the low pressure pulley is stable at the valve position A when oil is supplied to the low pressure pulley. That is, it is a fully closed state. On the other hand, when the oil returns from the low pressure pulley, the valve position B is stabilized. That is, the relief valve related to the low pressure pulley opens only the relief line related to the low pressure pulley.

  Next, as shown in the case 5 and the case 6, when the pulley driving pressure becomes equal, both the relief valves are stabilized at the valve position A while the oil is supplied to the pulley. On the other hand, both the relief valves are stabilized at the valve position D while the oil returns from the pulley.

  Next, when the oil is supplied to the pulley, the first check valve 9 and the second check valve 11 are opened and closed. As a result, the pulley drive pressure of the low-pressure pulley is always equal to the PL pressure that is at least required for the friction transmission of the CVT.

  On the other hand, when oil returns from the pulley, it is closed. When the check valve is closed, the feedback pressure rises to move the valve body, and the second port P2 of the relief valves 30 and 40 starts to open. As a result, the first relief line 7 or the second relief line 8 starts to open, and the oil returning from the low pressure pulley is drained to the low pressure circuit 110 through the first relief line 7 or the second relief line 8.

  As described above, in the hydraulic circuit 100, as shown in cases 2, 4 and 6, when both the first check valve 9 and the second check valve 11 are closed, the two relief valves are both positioned. Since it is between B and position E, at least one relief line is open. Further, as shown in cases 1, 3 and 5, when the relief valve is closed, at least one check valve is open. That is, in the hydraulic circuit 100, the two pulleys and the low pressure circuit 110 are always in communication. For this reason, the pulley drive pressure does not fluctuate even when the magnitude relationship of the pulley drive pressure is switched. Hereinafter, the operation of the hydraulic circuit 100 will be described in more detail.

  FIG. 11 shows that the PL control valve 60 (linear solenoid) controls the discharge pressure of the first pump 10 to be equal to the PL pressure, and at the same time, a constant amount of oil is supplied between the pulleys by the motor M (second pump 20). 6 is a graph showing the operation results of the first and second pulleys Pu1, Pu2, the relief valves 30, 40, and the check valves 9, 11 when they are alternately moved.

  11A shows the pulley drive pressures P1 and P2, FIG. 11B shows the oil flow rates Q1 and Q2 supplied to or returned from the pulley, and FIG. 11C shows the relief valves 30 and 40. Each valve position, (d) shows the oil flow rate QCHK1, QCHK2 flowing through the check valve. Also, the numbers at the bottom correspond to the case numbers in FIG.

  As shown in FIG. 11A, it can be seen that the pulley drive pressures are smoothly and alternately switched in magnitude without causing discontinuities. In particular, even when the magnitude relationship of the pulley driving pressure is alternately switched, it can be seen that the pulley driving pressure related to the low pressure pulley is always maintained at the PL pressure that is the minimum required for the friction transmission of the CVT.

  Further, as shown in FIG. 11B, it can be seen that the flow rate of the oil returning from the high pressure pulley is always zero and stable. This indicates that the oil related to the excess pressure exceeding the PL pressure is not drained from the high pressure pulley. On the other hand, as shown in Case 2 and Case 4, it can be seen that the oil returning from the low pressure pulley is drained.

  In addition, as shown in FIG. 11C, it can be seen that the relief valve related to the high pressure pulley is always stable at the valve position E. This is because, as shown in FIG. 11 (a), the driving pressure of the high pressure pulley is always higher than the PL pressure, so the check valve is closed and the feedback pressure of the relief valve becomes higher than the pilot pressure (PL pressure). It is.

  On the other hand, the relief valve related to the low-pressure pulley is stable at the valve position A when oil is supplied to the low-pressure pulley (Q1> 0 or Q2> 0). This is because the feedback pressure of the relief valve is lower than the pilot pressure (= PL pressure) because the driving pressure of the low pressure pulley is lower than the PL pressure.

  Further, it can be seen that when the oil returns from the low pressure pulley (Q1 <0 or Q2 <0), the valve position B is stabilized. This is because the pulley drive pressure exceeds the PL pressure, so the check valve closes and the feedback pressure of the relief valve increases.

  When the pulley drive pressures are equal (P1 = P2) and the immediately preceding relief valves 30, 40 are stable at the valve position E and the valve position A, respectively, the case 5 (FIG. 8) is shown. Thus, it can be seen that both the relief valves 30 and 40 are stable at the valve position A.

  On the other hand, when the pulley drive pressures are equal (P1 = P2) and the immediately preceding relief valves 30, 40 are stable at the valve position E and the valve position B, respectively, the case 6 (FIG. 9) is shown. Thus, it can be seen that both the relief valves 30 and 40 are stable at the valve position D.

  Further, as shown in FIG. 11 (d), it can be seen that oil flows to the first check valve 9 in case 3 and to the second check valve 11 in case 1, thereby supplying oil to the low pressure pulley.

  As described above, according to the hydraulic circuit 100 of the present invention, when the pressure reference of the pulley driving pressure is the PL pressure, and the first pulley driving pressure P1 or the second pulley driving pressure P2 is lower than the PL pressure, the pressure is related to the insufficient pressure. Oil is supplied from the low-pressure circuit 110 (first pump 10). On the other hand, when the first pulley driving pressure P1 or the second pulley driving pressure P2 exceeds the PL pressure, the oil related to the excess pressure exceeding the PL pressure is drained from the low pressure pulley having the lower pulley driving pressure. In particular, since the oil related to the excess pressure exceeding the PL pressure is drained from the low pressure pulley with the lower pulley driving pressure, the oil flow rate Q related to the high pressure pulley with the higher pulley driving pressure is always stable at zero.

  Furthermore, while both the first check valve 9 and the second check valve 11 are closed, either the first relief line 7 or the second relief line 8 which is a relief line is open. In contrast, while both the first check valve 9 and the second check valve 11 are open, both the first relief line 7 and the second relief line 8 are closed. That is, while the oil is being supplied / discharged to the first pulley Pu1 or the second pulley Pu2, the valve is not fully closed or fully opened in the hydraulic circuit 100, and the first pulley Pu1 and the second pulley Pu2 It always communicates with the first pump 10. Thereby, when the magnitude relationship of pulley drive pressure switches, the fluctuation | variation of pulley drive pressure is suppressed suitably. As a result, the pulley M can be smoothly controlled with no drive pressure discontinuity by the motor M that drives the second pump 20 and the linear solenoid of the PL control valve 60.

  Moreover, the unnecessary pulley drive pressure related to the pressure fluctuation is suitably suppressed, so that the discharge pressure of the first pump 10 is lowered, thereby reducing the pump drive power. As a result, energy loss can be reduced.

  The embodiment of the present invention is not limited to the above-described embodiment. Various changes and modifications can be made within the scope of the technical features of the present invention as described below.

FIG. 12 is an explanatory diagram showing a hydraulic circuit 200 according to another embodiment of the present invention.
In the hydraulic circuit 200, the connection positions of the first and second relief lines 7 and 8 with respect to the first and second relief valves 30 and 40 are opposite to the hydraulic circuit 100. That is, the first relief line 7 is connected to the third port P3 and the fifth port P5 in the first relief valve 30, and is connected to the second port P2 and the sixth port P6 in the second relief valve 40. On the other hand, the second relief line 8 is connected to the third port P3 and the fifth port P5 in the second relief valve 40, and is connected to the second port P2 and the sixth port P6 in the first relief valve 30.

  By the way, since the connection positions of the first and second relief lines 7 and 8 are reversed, the relief line related to the high-pressure pulley is opened first in that state. Therefore, the fifth line 5 is connected to the second line 2 while the sixth line 6 is connected to the first line 1 so that the relief line related to the low-pressure pulley is opened first. The configuration other than the above is the same as that of the hydraulic circuit 100.

FIG. 13 is an explanatory diagram showing a hydraulic circuit 300 according to another embodiment of the present invention.
The hydraulic circuit 300 is different from the hydraulic circuit 100 in the connection order of the second relief line 8 to the first and second relief valves 30 and 40. That is, the second relief line 8 is first connected to the third port P3 and the fifth port P5 of the first relief valve 30, and then connected to the second port P2 and the sixth port P6 of the second relief valve 40. The The configuration other than the above is the same as that of the hydraulic circuit 100.

FIG. 14 is an explanatory diagram showing a hydraulic circuit 400 according to another embodiment of the present invention.
The hydraulic circuit 400 is different from the hydraulic circuit 100 in the connection order of the first relief line 7 to the first and second relief valves 30 and 40. That is, the first relief line 7 is first connected to the third port P3 and the fifth port P5 of the second relief valve 40, and then connected to the second port P2 and the sixth port P6 of the first relief valve 30. The The configuration other than the above is the same as that of the hydraulic circuit 100.

1 1st line 2 2nd line 3 3rd line 4 4th line 5 5th line 6 6th line 7 1st relief line 8 2nd relief line 9 1st check valve 10 1st pump 11 2nd check valve 20 Second pump 30 First relief valve 40 Second relief valve 50 PL regulator valve 60 PL control valve 100, 200 Hydraulic circuit 300, 400 Hydraulic circuit 110 Low pressure circuit

Claims (6)

First and second hydraulic devices that operate in a pair, a first pump that constantly supplies a first hydraulic pressure that is at least necessary to drive the first and second hydraulic devices, and the first and second hydraulic devices A second pump for alternately supplying a second hydraulic pressure for control to the device, a first line connecting the first pump and the first hydraulic device, and connecting the first pump and the second hydraulic device. A first relief line branched from the first line; a second relief line branched from the second line; and the first and second relief lines according to a balance of forces of feedback pressure and pilot pressure. A pressure regulator that regulates the discharge pressure of the first pump to the first hydraulic pressure by the balance between the force of the feedback pressure and the pilot pressure, and the first relief valve and the second relief valve that respectively open and close the valve. A hydraulic circuit for hydraulic equipment having a valve,
The first and second lines include a first check valve and a second check valve, respectively, for preventing oil from flowing into the first pump,
The first and second relief lines are connected in series and cross to the first and second relief valves,
The first and second relief valves separately take in either one of the first driving pressure of the first hydraulic device or the second driving pressure of the second hydraulic device as feedback pressure, and the pilot pressure as the pilot pressure. A hydraulic circuit for hydraulic equipment, wherein the discharge pressure of the first pump is taken in separately.   2. The hydraulic pressure for a hydraulic device according to claim 1, wherein the first and second relief valves each have two communication oil passages of different systems configured to open sequentially as the feedback pressure increases. circuit.   While the oil is being supplied to the first and second hydraulic devices, the relief valve with the higher feedback pressure is in a state in which all of the two communicating oil passages are open, and the relief valve with the lower feedback pressure. The hydraulic circuit for hydraulic equipment according to claim 2, wherein all the second communication oil passages are closed.   While the oil backflows from the first and second hydraulic devices, the relief valve with the higher feedback pressure is in a state in which all of the two communicating oil passages are open, while the feedback pressure is lower. 3. The hydraulic circuit for hydraulic equipment according to claim 2, wherein the relief valve is in a state in which only a communication oil passage related to the hydraulic equipment having a lower driving pressure is open.   2. The linear solenoid that supplies a pilot pressure related to the first hydraulic pressure to the pressure regulating valve is provided, and an original pressure of the linear solenoid is a discharge pressure of the first pump. Hydraulic circuit for hydraulic equipment.   The hydraulic circuit for a hydraulic device according to any one of claims 1 to 5, wherein the first and second hydraulic devices are a pair of pulley mechanisms.

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