JP2017207191A - Hydraulic circuit for hydraulic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a motor for driving an electric pump compact, in a hydraulic circuit which supplies hydraulic pressure needed for pulley gear ratio control alternately by the electric pump while always supplying base hydraulic pressure to a pulley mechanism by a driving pump.SOLUTION: A limit valve 30 which controls pressure of a pressure control object to a fixed value by a balance of power between feedback pressure and pilot pressure, is provided between a second pump 20 for alternately moving oil between both pulleys, and a DN pulley Pu2. The pressure control object of the limit valve 30 is pressure PA on the side of the port P22 of the second pump 20, and the limit valve introduces DR pulley drive pressure PDR as the feedback pressure and the pressure PA on the side of the port P22 of the second pump 20 as the pilot pressure, respectively. Further, in a valve body 31 of the limit valve 30, an action area S1 on which the pressure PA acts and an action area S2 on which the DR pulley drive pressure PR acts, are made equal to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic circuit for a hydraulic device, and more specifically, to a hydraulic device that operates as a pair, the first pump always supplies the first hydraulic pressure that is the minimum required for the operation of the device, and the second pump changes the speed of the device. The present invention relates to a hydraulic circuit for hydraulic equipment that alternately supplies a second hydraulic pressure necessary for control.

  Conventionally, a first electric pump that supplies a hydraulic pressure (secondary pressure) necessary for holding the belt capacity to the second pulley, and a second oil that alternately moves oil necessary for shifting between the first pulley and the second pulley. These two electric pumps are used to directly drive the driving pressure (primary pressure) of the first pulley and the driving pressure (secondary pressure) of the second pulley without using a pressure control valve, a linear solenoid or the like. A hydraulic circuit for a belt type continuously variable transmission (CVT) configured to be controlled is known (for example, see Patent Document 1).

  In the CVT hydraulic circuit, a first controller for controlling the first motor that drives the first electric pump and a second controller for controlling the second motor that drives the second electric pump are separately provided. Independently prepared. The first controller controls the first motor while adding feedforward compensation that corresponds to a change in the shift flow rate to the second electric pump to feedback control that makes the actual secondary pressure coincide with the target secondary pressure. On the other hand, the second controller controls the second motor while limiting the shift flow rate of the second electric pump so that the driving pressure of the first pulley does not fall below the minimum primary pressure.

JP 2000-193075 A

  By the way, when changing the gear ratio (pulley ratio) in a very short time such as sudden stop or kick down, it is necessary to generate a high pulley driving pressure (hydraulic pressure) in a very short time. In order to generate high hydraulic pressure with an electric pump, a motor that generates large torque (power) is required.

  In the case of the hydraulic circuit for CVT described in Patent Document 1, the drive pressure (primary pressure) of the first pulley and the drive pressure (secondary pressure) of the second pulley are directly controlled using two electric pumps. Therefore, it is considered that the primary pressure and the secondary pressure necessary for sudden shifting such as sudden stop or kick down can be instantaneously secured.

  However, in the case of the above hydraulic circuit, since all of the hydraulic energy applied to the pulley is supplied from two motors (first and second motors), the driving torque of the second motor is inevitably required for sudden stop or kickdown. Become bigger. Similarly, the driving torque of the first motor inevitably increases as the vehicle develops and climbs up.

  As a result, when all of the hydraulic energy required for the pulley in all driving situations is provided by the first and second motors, there is a problem that the size and weight of each motor, and thus the size and weight of the entire hydraulic circuit increase.

  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. Provided is a hydraulic circuit for a hydraulic device in which a motor for driving the second pump can be miniaturized in a hydraulic circuit that alternately supplies a second hydraulic pressure necessary for gear shift control of the device by a second pump while supplying the hydraulic circuit. is there.

  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 a base oil pressure that is necessary, a second pump (20) that alternately moves oil between the first and second hydraulic devices, and the first pump (10) And a first line (1) connecting the second hydraulic device (Pu2), a second line (2) connecting the second pump (20) and the first hydraulic device (Pu1), and the second A third line (3) that connects the pump (20) and the second hydraulic device (Pu2), and a first valve (30) that regulates the pressure regulation target to a constant value by the balance between the feedback pressure and the pilot pressure. A hydraulic circuit including the first circuit The lube (30) is disposed between the second pump (20) and the second hydraulic device (Pu2), and serves as the feedback pressure on the second hydraulic device (Pu2) side of the second pump (20). The pressure (PA) is taken in, and the driving pressure (PDR) of the first hydraulic device (Pu1) is taken in as a pilot pressure.

  In the above configuration, the pilot pressure of the first valve (30) is the driving pressure (PDR) of the first hydraulic device, which is the pressure on the first hydraulic device (Pu1) side of the second pump (20). The feedback pressure (pressure to be regulated) is the pressure (PA) on the second hydraulic equipment (Pu2) side of the second pump (20). That is, the first valve (30) is driven by the differential pressure (P20) while taking in the differential pressure (P20) of the second pump (20). Therefore, adjusting the pressure to be regulated (PA) is equivalent to regulating the differential pressure (P20) of the second pump (20).

  Therefore, for example, when the pressure to be regulated (PA), that is, the driving pressure (PDN) of the second hydraulic device is larger than the driving pressure (PDR) of the first hydraulic device, the difference between the second pump (20). When the pressure (P20) exceeds a preset value (set pressure), the first valve (30) reduces the pressure (PA) to be regulated, and thereby the differential pressure (P20) of the second pump (20). Can be adjusted to a constant value (f (X1), f (X2)). That is, the differential pressure (P20) of the second pump (20) can be limited to a certain value or less.

  Accordingly, it is possible to suppress an increase in torque (an increase in output) of the motor (M) that drives the second pump (20) in an abrupt shift state such as a sudden stop or a kick down. As a result, the motor (M) that drives the second pump (20) can be downsized.

  The second feature of the hydraulic circuit for hydraulic equipment according to the present invention is that the first valve (30) includes a valve body (31) having irregularities formed on an outer peripheral surface, and a body (32) on which the valve body slides. And a pressure (PA) on the second hydraulic equipment (Pu2) side of the second pump (20) and a driving pressure of the first hydraulic equipment (Pu1). (PDR) acts on both shaft ends of the valve body (31).

  In the above configuration, the load pressure (f (X)) of the spring (33) and the differential pressure (P20) of the second pump (20) act on the valve body (31) simultaneously. Therefore, when the differential pressure (P20) of the second pump (20) exceeds the initial load pressure (f (0)) of the spring (33), the valve body (31) starts to move quickly in the axial direction. The valve element (31) is stationary at a position where the load pressure (f (X)) of the spring (33) and the differential pressure (P20) of the second pump (20) are balanced. This means that the differential pressure (P20) of the second pump (20) can be made equal (regulated) to the load pressure (f (X)) of the spring (33) by the first valve (30). Is shown.

  Therefore, for example, when the differential pressure (P20) of the second pump (20) is balanced with the load pressure (f (X)) of the spring (33), the convex portion (31a) formed on the valve body (31). By closing one port (P4) or communicating between the ports (P3-P2) by the recess (31b), the differential pressure (P20) of the second pump (20) is kept at a constant value (f (X)). It is possible to regulate the pressure. Thus, when the driving pressure (PDN) of the second hydraulic device is larger than the driving pressure (PDR) of the first hydraulic device, the torque (output increase) of the motor (M) that drives the second pump (20) is increased. It becomes possible to suppress.

  According to a third feature of the hydraulic circuit for hydraulic equipment according to the present invention, the first valve (30) includes a first oil passage (P4-P3) and a second oil passage (P3-P2) inside, and The valve body (31) has a first valve position (B) for closing the first oil passage, and the valve body (31) has a second valve position (C) for opening the second oil passage.

  In the above configuration, the first valve (30) has two different limit values or pressure regulation values (f (X1), f (X2) with respect to the differential pressure (P20) of the second pump (20) to be regulated. )) Will have. Thereby, for example, according to the direction of the oil flowing through the second pump (20) (the direction flowing into the first hydraulic device (Pu1) or the direction flowing out from the first hydraulic device (Pu1)), the second pump ( 20), the differential pressure (P20) can be suppressed below the limit value.

  A fourth feature of the hydraulic circuit for a hydraulic device according to the present invention is that the valve element (31) acts on the pressure (PA) on the second hydraulic device (Pu2) side of the second pump (20). (S1) and the action area (S2) of the valve body (31) on which the driving pressure (PDR) of the first hydraulic device (Pu1) acts are equal to each other.

  In the above configuration, the relationship between the differential pressure (P20) of the second pump (20) and the movement amount (X) of the valve body (31) is simplified (linearized). Thereby, the limit value (f (X)) for the differential pressure (P20) of the second pump (20) can be easily set.

  The fifth feature of the hydraulic circuit for hydraulic equipment according to the present invention is that the discharge pressure of the first pump (10) is changed to the driving pressure (PDN) of the second hydraulic equipment (Pu2) by balancing the force of the feedback pressure and the pilot pressure. A second valve (40) that regulates pressure, a linear solenoid (50) that supplies pilot pressure to the second valve (40), and a third valve (60) that supplies original pressure to the linear solenoid (50). ).

  With the above configuration, the discharge pressure of the first pump (10) can be quickly adjusted to a desired pressure without depending on the motor. This makes it possible to mechanically configure a base hydraulic pressure source that is at least necessary for driving the device. This contributes to downsizing of the entire hydraulic circuit.

  A sixth feature of the hydraulic circuit for hydraulic equipment according to the present invention is that a fifth line (5) for supplying feedback pressure to the first valve (30) is connected to the first line (9) via a check valve (9). 1) to connect.

  As described above, for example, when the driving pressure (PDN) of the second hydraulic device is larger than the driving pressure (PDR) of the first hydraulic device, the differential pressure (P20) of the second pump (20) is the set pressure. When exceeding, the valve body (31) of the first valve (30) moves in the axial direction and the differential pressure (P20) of the second pump (20) is adjusted to a constant value (f (X1), f (X2)). Press. When the pressure difference (P20) falls below a certain value, the valve body (31) of the first valve (30) moves in the opposite axial direction and starts to return to the original position (valve position A).

  In this case, the oil in the fifth line (5) hinders the movement (return) of the valve body (31). In the worst case, the valve body (31) cannot return (return) to the original position (valve position A).

  Therefore, the fifth line (5) is connected to the first line (1) via the check valve (9). Thereby, when the line pressure (PA) of the fifth line (5) becomes higher than the driving pressure (PDN) of the second hydraulic device, the check valve (9) is opened. By opening the check valve (9), the oil related to the excess pressure in the fifth line (5) is discharged through the check valve (9). As a result, the first valve (30) can be returned to normal.

  A seventh 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 base hydraulic pressure that is at least required for the frictional transmission of the pulley is stably supplied by the first pump (10). On the other hand, the hydraulic pressure required for pulley gear ratio control is quickly supplied by the second pump (20). Further, when the driving pressure (PDN) of the second hydraulic device is larger than the driving pressure (PDR) of the first hydraulic device and the differential pressure (P20) of the second pump (20) exceeds the set pressure, The first valve (30) is actuated instantaneously to limit the differential pressure (P20) of the second pump (20) to a certain value or less. Thereby, when the driving pressure (PDN) of the second hydraulic device is larger than the driving pressure (PDR) of the first hydraulic device, the differential pressure (P20) of the second pump (20) is limited to a certain value or less. It becomes possible. As a result, it is possible to suppress an increase in torque (an increase in output) of the motor (M) that drives the second pump (20). As a result, the motor (M) can be downsized, and even when the output of the motor (M) is small, quick gear ratio control such as kickdown and sudden stop can be performed.

  According to the hydraulic circuit for hydraulic equipment of the present invention, the first pump is always supplied with the first hydraulic pressure that is the minimum required for the operation of the equipment to the hydraulic equipment that operates in a pair, and the gear change control of the equipment is performed by the second pump. In the hydraulic circuit that alternately supplies the necessary second hydraulic pressure, the motor (M) that drives the second pump (20) can be reduced in size.

It is explanatory drawing which simplified and showed the structure of the hydraulic circuit which concerns on this embodiment. It is principal part explanatory drawing which shows the limit valve which concerns on this embodiment. It is explanatory drawing which shows the valve position of the limit valve which concerns on this embodiment. It is a graph which shows the time-sequential change of each data at the time of controlling the motor of a 2nd pump so that a pulley control apparatus may make an actual pulley position equal to a target pulley position. It is explanatory drawing which shows the position command and external force which concern on this embodiment. It is explanatory drawing which shows operation | movement of this hydraulic circuit in the valve position A of the limit valve which concerns on this embodiment. It is explanatory drawing which shows operation | movement of this hydraulic circuit in the valve position B of the limit valve which concerns on this embodiment. It is explanatory drawing which shows operation | movement of this hydraulic circuit in the valve position C of the limit valve which concerns on this embodiment.

  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 uses the first pump 10 and the second pump 20 together to drive a pulley (hereinafter referred to as “DR pulley”) Pu1 of a belt type continuously variable transmission (hereinafter also referred to as “CVT”). This is a hydraulic circuit for CVT that supplies oil (hydraulic pressure) to a driven pulley (hereinafter referred to as “DN pulley”) Pu2. The first pump 10 supplies a minimum pressure (= constant value) required for friction transmission of the CVT to the DR pulley Pu1 and the DN pulley Pu2. On the other hand, the second pump 20 alternately moves the oil between the pulleys Pu1 and Pu2, so that the pressure required for CVT gear ratio control (hereinafter also referred to as “speed gear ratio pressure”) is supplied to the DR pulley Pu1. Or it supplies alternately to DN pulley Pu2.

  In particular, a pump differential pressure limiting mechanism 110 (a portion surrounded by a one-dot chain line) is provided between the second pump 20 and the DN pulley Pu2. Although details will be described later, the pump differential pressure limiting mechanism 110 is a case where the DN pulley drive pressure PDN is larger than the DR pulley drive pressure PDR, and the differential pressure P20 of the second pump 20 is a preset value (set pressure). ), The second pump differential pressure P20 is configured to be limited to a certain value or less.

  When the second pump differential pressure P20 is limited to a certain value or less, the torque (output) of the motor M that drives the second pump 20 increases, for example, in a sudden shift state such as a sudden stop or kick-down from a cruise state. Can be suitably suppressed. As a result, the motor M can be reduced in size. The “second pump differential pressure P20” referred to here means a pressure difference between ports P21 with respect to the port P22. In the hydraulic circuit 100, the second pump differential pressure P20 is equal to the difference between the “DR pulley drive pressure PDR” and the “pressure PA at point A” (that is, P20 = PDR−PA). Hereinafter, the direction in which the DR pulley driving pressure PDR becomes higher than the pressure PA at the point A may be referred to as “differential pressure positive direction”, and the direction in which the DR pulley driving pressure PDR becomes lower may be referred to as “differential pressure negative direction”.

  Further, the pressure PA at the point A is always equal to the DN pulley drive pressure PDN when the third port P3 and the fourth port P4 of the limit valve 30 communicate with each other.

  As the configuration of the hydraulic circuit 100, the first line 1 that connects the first pump 10 and the DN pulley Pu2, the second line 2 that connects the second pump 20 and the DR pulley Pu1, and the second pump 20 and DN. The third line 3 connecting the pulley Pu2, the fourth line 4 branched from the second line 2 and connected to the limit valve 30, and the fifth line 5 branched from the third line 3 and connected to the limit valve 30 And the sixth line 6 connecting the limit valve 30 and the reservoir 7, the reservoir 7 storing oil, and the fifth line 5 and the first line 1 when the pressure at the point A exceeds the DN pulley driving pressure PDN. The difference between the check valve 9 to be communicated, 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 second pump 20 under certain conditions. A limit valve 30 that limits P20 to a certain value, a PDN regulator valve 40 that regulates the DN pulley drive pressure PDN to a set pressure, and a pilot pressure that serves as a pressure regulation reference pressure (set pressure) for the PDN regulator valve 40 is supplied. A PDN solenoid valve 50 and a clutch reducing valve 60 for supplying a source pressure to the PDN solenoid valve 50 are provided. Hereinafter, each configuration will be described in more detail.

  The first line 1 is an oil passage for transferring oil discharged from the first pump 10 to the DR pulley Pu1 and the DN pulley Pu2. The first line 1 and the third line 3 communicate with each other at a point C1 in the drawing. Accordingly, a part of the oil discharged from the first pump 10 is supplied to the DN pulley Pu2, and the rest is supplied to the second pump 20 through the third line 3. The oil supplied to the second pump 20 is boosted by the second pump 20, and then supplied to the DR pulley Pu1 through the second line 2.

  The second line 2 is an oil passage for transferring oil related to the transmission specific pressure (second pump differential pressure P20) to the DR pulley Pu1. The line pressure of the second line 2 (that is, the DR pulley driving pressure PDR) is supplied as a pilot pressure to the limit valve 30 via the fourth line 4.

  The third line 3 includes a third line 3 a that connects the second pump 20 and the limit valve 30, and a third line 3 b that connects the limit valve 30 and the first line 1. Similarly to the second line 2, the third line 3 is an oil passage for transferring oil related to the transmission specific pressure (second pump differential pressure P20) to the DN pulley Pu2.

  The line pressure of the third line 3 a (that is, the pressure PA at the point A) is supplied as a feedback pressure to the limit valve 30 via the fifth line 5. Accordingly, the second pump differential pressure P20 (= PDR-PA) always acts on the valve body 31 (FIG. 2) of the limit valve 30 via the fourth line 4 and the fifth line 5.

  The limit valve 30 has five ports P1 to P5 outside, a first oil passage that communicates the third port P3 and the fourth port P4, and a second fluid that communicates the third port P3 and the second port P2. The oil passage is configured to be selectively switched.

  Further, the limit valve 30 has three valve positions indicated by A to C described later. Therefore, as will be described in detail later, when the second pump differential pressure P20 exceeds the set pressure in the negative differential pressure direction, the valve body moves from the valve position A to B or C, and the fourth port P4 (third line 3) The oil is drained into the reservoir 7 by closing the throttle while closing or opening the second port P2 (sixth line 6).

  That is, the limit valve 30 introduces the pressure PA at the point A as a feedback pressure and the DR pulley driving pressure PDR as a pilot pressure, and the second pump differential pressure P20 (= PDR-PA) is a set pressure in the negative direction of the differential pressure. When the pressure exceeds the value, the second pump differential pressure P20 operates so as to limit (regulate) the pressure difference to a predetermined value or less. Therefore, the pressure adjustment target of the limit valve 30 is the pressure PA at the point A. In the valve body 31 (FIG. 2), the acting area S1 where the pressure PA at the point A acts and the acting area S2 where the DR pulley driving pressure PDR acts are set to be equal to each other. Therefore, adjusting the pressure PA at the point A by the limit valve 30 is equivalent to adjusting the second pump differential pressure P20 as a result.

  The PDN regulator valve 40 takes in the discharge pressure of the first pump 10 as a source pressure and a feedback pressure, and the DN pulley drive pressure PDN is made equal to the pilot pressure by the balance between the feedback pressure, the pilot pressure, and the spring load pressure. Adjust pressure. The pilot pressure is supplied by the PDN solenoid valve 50.

  The PDN solenoid valve 50 regulates the outlet pressure of the clutch reducing valve 60 as a source pressure to be equal to the command value (PDNCCMD) by a linear solenoid, and outputs the output value to the PDN regulator valve 40 as a pilot pressure.

  The clutch reducing valve 60 takes the discharge pressure of the first pump 10 as an original pressure and takes the outlet pressure as a feedback pressure, so that the outlet pressure becomes equal to the spring load pressure by balancing the force between the feedback pressure and the spring load pressure. Adjust pressure.

  Therefore, the PDN regulator valve 40, the PDN solenoid valve 50, and the clutch reducing valve 60 can make the discharge pressure of the first pump 10 equal to the command value (PDNCMD) stably and quickly.

  The first pump 10 is a positive displacement pump, for example, an internal gear pump. The base hydraulic pressure required for the CVT friction transmission is supplied to the DR pulley Pu1 and the DN pulley Pu2.

  The second pump 20 is a reciprocating pump that moves oil necessary for gear ratio control alternately from one pulley to the other pulley. Accordingly, when oil is supplied to the DR pulley Pu1, the port P21 serves as a discharge port and the port P22 serves as a suction port. On the other hand, when oil is supplied to the DN pulley Pu2, the port P22 serves as a discharge port and the port P21 serves as a suction port.

  In the present embodiment, the oil flow rate (second pump flow rate) Q20 of the second pump 20 is almost equal to the oil flow rate (DR pulley flow rate) QDR of the DR pulley Pu1. That is, most of the oil that flows out (returns) from the DR pulley Pu1 flows into the point A via the second pump 20. On the other hand, most of the oil flowing (sent out) into the DR pulley Pu1 flows out from the point A via the second pump 20.

  The pulley control unit PCU controls the output (power) of the motor M of the second pump 20 so that the actual pulley position PISA follows (closes to) the target pulley position PIST. This will be described later with reference to FIG.

  FIG. 2 is an explanatory cross-sectional view of a relevant part showing a limit valve 30 according to the present embodiment. For convenience of explanation, oil passages (third lines 3a and 3b, fourth line 4, fifth line 5, and sixth line 6) connected to each port are also illustrated.

  The limit valve 30 includes a valve body 31, a body 32, and a spring 33. The valve body 31 includes, in order from the left in the axial direction, a first circumferential convex portion 31a for restricting or closing the fourth port P4, a fourth port P4 and a third port P3, or a third port P3 and a second port P2. A first circumferential recess 31b that selectively communicates with a second circumferential projection 31c for narrowing or closing the second port P2 is formed.

  The body 32 includes a first port P1 for introducing the pressure (= DR pulley driving pressure PDR) of the port P21 of the second pump 20 through the fourth line 4 and the sixth line 6 in order from the right side in the axial direction. A second port P2 for draining oil to the reservoir 7, a third port P3 for exchanging oil from the DR pulley Pu1, a fourth port P4 for exchanging oil from the DN pulley Pu2, A fifth port P5 for introducing the pressure of the port P22 of the second pump 20 (= pressure PA at the point A) is formed through the five lines 5, respectively. 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 valve body 31, an axial projection area (piston action area) S1 on which the pressure of the port P22 of the second pump 20 acts and an axial projection area (piston action) on which the pressure of the port P21 of the second pump 20 acts. Area) S2 is equal. As a result, the relationship between the second pump differential pressure P20 and the movement amount X of the valve body 31 is simplified. For example, when the spring load when the movement amount of the valve body 31 is X is K · (X0 + X) (K: spring constant, X0: initial contraction amount), the balance of force when the valve body 31 is stationary is: PA × S1 = PDR × S2 + K · (X0 + X), that is, PA−PDR = (K / S1) · (X0 + X) (≡f (X)). That is, the spring load pressure f (X) when the valve body 31 is stationary is equal to the limit value (limit value) of the second pump differential pressure P20.

  Therefore, as the first limit value of the second pump differential pressure P20 limited by the limit valve 30, the spring load pressure f (X1) (= (K / S1) · ( X0 + X1)) can be set. X1 is the amount of movement from the left end portion 32a of the valve body 31 immediately before the first circumferential convex portion 31a closes the opening of the fourth port P4. In this case, the fourth port P4 is closed when the second pump differential pressure P20 becomes equal to the spring load pressure f (X1).

  This first limit value is the second pump differential pressure P20 that the limit valve 30 limits when the DN pulley drive pressure PDN is greater than the DR pulley drive pressure PDR and the oil flows into the DR pulley Pu1. It is.

  As the second limit value of the other second pump differential pressure P20 limited by the limit valve 30, the spring load pressure f (X2) (= (K / S1) · ( X0 + X2)) can be set. X2 is the amount of movement of the valve body 31 from the left end portion 32a immediately before the second circumferential convex portion 31c opens the second port P2 opening. In this case, when the second pump differential pressure P20 becomes equal to the spring load pressure f (X2), the second port P2 is opened, and the oil is drained to the reservoir 7 via the sixth line 6.

  This second limit value is the second pump differential pressure P20 that the limit valve 30 limits when the DN pulley drive pressure PDN is greater than the DR pulley drive pressure PDR and the oil flows out of the DR pulley Pu1. It is.

  FIG. 3 is an explanatory diagram showing the valve position of the limit valve 30 according to the present embodiment.

  At the valve position A, the initial spring load pressure f (0) (= (K / S1) · (X0)) exceeds the second pump differential pressure P20, and the valve element 31 is pushed by the spring 33 and the left end portion. It is in a state of hitting 32a. In this case, both the fourth port P4 and the third port P3 are open. Therefore, the third line 3 is in an open state (communication state). The initial spring load pressure f (0) may be simply referred to as “set pressure”.

  The valve position B is a state immediately before the fourth port P4 is closed by the first circumferential convex portion 31a. When the second pump differential pressure P20 exceeds the initial spring load pressure f (0) at the valve position A, the valve body 31 starts to move to the right in the axial direction. As the valve body 31 moves, the fourth port P4 is throttled. As the fourth port P4 is throttled, the pressure PA at the point A decreases. Eventually, the valve body 31 is balanced around the valve position B where the fourth port P4 is closed by the first circumferential convex portion 31a. When the valve body 31 is balanced around the valve position B, the second pump differential pressure P20 is regulated to a constant value (= spring load pressure f (X1)).

  When the second pump differential pressure P20 becomes smaller than the spring load pressure f (X1) at the valve position B, the valve body 31 is pushed to the left in the axial direction by the spring 33 and starts to return to the valve position A side.

  The valve position C is a state immediately after the second port P2 is opened by the second circumferential protrusion 31c. Even when the fourth port P4 is closed at the valve position B, if the second pump differential pressure P20 exceeds the spring load pressure f (X1), the valve body 31 passes through the valve position B and further in the axial direction. Start moving to the right. And the valve body 31 comes to balance centering on the valve position C where the spring load pressure f (X2) and the 2nd pump differential pressure P20 balance. When the valve body 31 is balanced around the valve position C, the oil is drained to the reservoir 7 and the second pump differential pressure P20 is regulated to a constant value (= spring load pressure f (X2)).

  When the second pump differential pressure P20 becomes smaller than the spring load pressure f (X2) at the valve position C, the valve body 31 is pushed to the left in the axial direction by the spring 33 and begins to return to the valve position A side.

  As described above, when the second pump differential pressure P20 exceeds the initial spring load pressure f (0), the valve body 31 moves to the right in the axial direction and first throttles the fourth port P4 related to opening and closing of the third line 3. The second pump differential pressure P20 is adjusted to a constant value (= f (X1)). And even if the 4th port P4 is closed, when 2nd pump differential pressure P20 is larger than spring load pressure f (X1), it moves to the axial direction right further, and it is 2nd concerning opening and closing of the 6th line 6 The port P2 is opened, and the second pump differential pressure P20 is adjusted to a constant value (= f (X2)) while draining oil.

  As described above, the limit valve 30 operates from the valve position A to B or from the valve position A to C according to the direction of the oil flowing through the second pump 20 to keep the second pump differential pressure P20 constant. Regulate to the value.

  FIG. 4 shows the time series change of each data when the pulley control unit PCU controls the motor M of the second pump 20 so that the actual pulley position PISA becomes equal to the target pulley position PIST (FIG. 5A). It is a graph to show.

  As shown in FIG. 5A, a 2-cycle sine wave vibration having a period of 8T returning from the minimum pulley position L to the minimum pulley position L via the maximum pulley position 4L was given as the target pulley position PIST. The actual pulley position PISA here is the position of the DR pulley Pu1.

  Further, in order to simulate the transmission of force from the DR pulley Pu1 to the DN pulley Pu2 via the belt, an external force shown in FIG. 5B is applied to the DR pulley Pu1 and the DN pulley Pu2. The external force is loaded with a two-cycle sinusoidal load having an amplitude of F / 4 and a period of 4T in order to simulate a traveling state from time 2T to 10T. On the other hand, from time 10T to 18T, a two-cycle sine wave load having an amplitude of 4F and a period of 4T is applied in order to simulate a sudden shift state such as a sudden stop or kick-down.

  Returning to FIG. 4 again, the data are, in order from the top, the pulley flow rate QDR, QDN and the second pump flow rate Q20, the pulley drive pressure PDR, PDN and the command value PDNCMD, the second pump differential pressure P20 and the pressure PA at point A, and The time-series changes from the time 2T to the time 18T regarding the valve position of the limit valve 30 are respectively shown. Hereinafter, each data will be described.

  5A, it can be seen that the actual pulley position PISA almost coincides with the target pulley position PIST. The actual pulley position PISA corresponds to the stroke of the piston of the DR pulley Pu1, and when the actual pulley position PISA is displaced in the plus direction, the piston of the DR pulley Pu1 extends and the distance between the two conical surfaces of the DR pulley Pu1 is Since it narrows, the pulley groove width decreases. On the other hand, when the actual pulley position PISA is displaced in the minus direction, the pulley groove width increases.

  4 (a) and 5 (a), while the oil flows into the DR pulley Pu1 (while the oil flows out from the DN pulley Pu2), the actual pulley position PISA has a pulley groove width. Increase in the direction of shrinking. On the other hand, while the oil flows out from the DR pulley Pu1 (while the oil flows into the DN pulley Pu2), the pulley width of the actual pulley position PISA decreases in the expansion direction.

  In this case, the second pump flow rate Q20 is almost equal to the DR pulley flow rate QDR.

  Next, with reference to FIGS. 4B and 5B, the DN pulley drive pressure PDN in the present embodiment is regulated to the command value PDNCMD (= 2a [bar]) by the PDN regulator valve 40 and the like. On the other hand, the DR pulley driving pressure PDR is equal to a pressure obtained by adding a predetermined sinusoidal pressure to the DN pulley driving pressure PDN. The “sinusoidal pressure” means the second pump differential pressure P20 that is not limited by the limit valve 30.

  In the present embodiment, the relationship of PDR = PDN + kF (k is a positive constant) is established among the external force F, the DR pulley driving pressure PDR, and the DN pulley driving pressure PDN. That is, the DR pulley driving pressure PDR is always equal to the sum of the DN pulley driving pressure PDN and the pressure difference caused by the external force F. Therefore, the DR pulley drive pressure PDR is uniquely determined by the DN pulley drive pressure PDN and the external force F regardless of the operation of the limit valve 30.

  Next, in FIG. 4C, the second pump differential pressure P20 in the negative differential pressure direction from time 2T to 10T is set to less than 0.3a [bar]. On the other hand, the second pump differential pressure P20 in the negative direction of the differential pressure from time 10T to 18T is set to 0.3a [bar] or less.

  In particular, from time t1 (> 12T) to t2 (<14T), the second pump differential pressure P20 in the negative differential pressure direction is limited to a constant value (= f (X1)). This is because when the second pump differential pressure P20 in the negative differential pressure direction exceeds the set pressure (initial spring load pressure f (0)), the limit valve 30 operates and the second pump differential pressure P20 in the negative differential pressure direction. Is limited to a constant value (= spring load pressure f (X1)).

  In this case, the limit valve 30 reduces the pressure PA at the point A by restricting the fourth port P4. As the pressure PA at the point A decreases, the second pump differential pressure P20 (= PDR−PA) in the negative differential pressure direction is adjusted to a constant value (= spring load pressure f (X1)).

  Similarly, from time t3 (> 16T) to t4 (<18T), the second pump differential pressure P20 in the negative differential pressure direction is limited to a constant value (= f (X2)). This is because when the second pump differential pressure P20 in the negative differential pressure direction exceeds the set pressure (= initial spring load pressure f (0)), the limit valve 30 is operated and the second pump differential pressure in the negative differential pressure direction. This is because P20 is limited to a constant value (= spring load pressure f (X2)).

  In this case, the limit valve 30 reduces the pressure PA at the point A by opening the second port P2 and draining the oil to the reservoir 7. As the pressure PA at the point A decreases, the second pump differential pressure P20 (= PDR-PA) is regulated to a constant value (= spring load pressure f (X2)).

  Next, in FIG. 4D, when the oil is flowing into the DR pulley Pu1 (QDR> 0), the second pump differential pressure P20 in the negative differential pressure direction is set pressure (initial spring load pressure f ( 0)), the limit valve 30 operates from the valve position A to B, and regulates the second pump differential pressure P20 in the negative differential pressure direction to a constant value (= spring load pressure f (X1)).

  On the other hand, when the oil flows out from the DR pulley Pu1 (QDR <0) and the second pump differential pressure P20 in the negative differential pressure direction exceeds the set pressure, the limit valve 30 moves from the valve position A to C. The second pump differential pressure P20 in the negative differential pressure direction is adjusted to a constant value (= spring load pressure f (X2)).

  FIG. 6 is an explanatory diagram showing the operation of the hydraulic circuit 100 at the valve position A of the limit valve 30. In the figure, the one-dot chain line indicates a pressure range equal to the DR pulley driving pressure PDR, and the solid line indicates a pressure range equal to the DN pulley driving pressure PDN. The same applies to the following.

  In this case, the limit valve 30 is inactive. In the limit valve 30, the third port P3 and the fourth port P4 communicate with each other. While the first pump 10 supplies the base hydraulic pressure (= PDN) that is at least necessary for the friction transmission of the CVT, the second pump 20 supplies the oil related to the speed change ratio from the DR pulley Pu1 to the DN pulley Pu2 or the DN pulley Pu2. To DR pulley Pu1 alternately.

  FIG. 7 is an explanatory diagram showing the operation of the hydraulic circuit 100 at the valve position B of the limit valve 30. The dotted line in the figure is the pressure PA at point A. The same applies to the following.

  In this case, the direction in which the oil flows in the second pump 20 is the direction in which the oil flows into the DR pulley Pu1. That is, the DR pulley flow rate QDR is in a positive state. The direction of the second pump differential pressure P20 is the differential pressure minus direction.

  The limit valve 30 is operating at the valve position B. That is, the pressure PA at the point A is regulated while the fourth port P4 is being throttled, and thereby the second pump differential pressure P20 (= PDR−PA) in the negative differential pressure direction is a constant value (= spring load pressure f (X1)). The pressure is adjusted. Thereby, the torque increase of the motor M which drives the 2nd pump 20 is suppressed suitably.

  When the second pump differential pressure P20 (= PDR−PA) in the negative differential pressure direction becomes smaller than a certain value (= spring load pressure f (X1)), the limit valve 30 returns to the valve position A.

  FIG. 8 is an explanatory diagram showing the operation of the hydraulic circuit 100 at the valve position C of the limit valve 30.

  In this case, the oil flowing direction in the second pump 20 is a direction in which the oil flows out from the DR pulley Pu1. That is, the DR pulley flow rate QDR is in a negative state. The direction of the second pump differential pressure P20 is the differential pressure minus direction.

  The limit valve 30 is operating at the valve position C. That is, the second port P2 is opened and the pressure PA at the point A is regulated while draining the oil to the reservoir 7, thereby the second pump differential pressure P20 (= PDR-PA) in the negative differential pressure direction is set to a constant value (= The pressure is adjusted to the spring load pressure f (X2)). Thereby, the torque increase of the motor M which drives the 2nd pump 20 is suppressed suitably.

  When the second pump differential pressure P20 (= PDR−PA) in the negative differential pressure direction becomes smaller than a certain value (= spring load pressure f (X2)), the limit valve 30 returns to the valve position A.

  The oil is also filled in the fifth line 5 while the oil is drained to the reservoir 7 via the second port P2. Thereby, the pressure PA at the point A is temporarily higher than the DN pulley drive pressure PDN. In this case, the check valve 9 changes from the closed state to the open state. When the check valve 9 is opened, the oil related to the excess pressure exceeding the DN pulley driving pressure PDN is discharged to the DN pulley Pu2 side. As a result, the limit valve 30 can return to the valve position A.

  As described above, according to the hydraulic circuit 100, when the DN pulley driving pressure PDN is smaller than the DR pulley driving pressure PDR (when the second pump differential pressure P20 is in the negative direction of the differential pressure), the second pump differential pressure P20 is obtained. When the pressure exceeds a preset value (set pressure), the limit valve 30 operates so as to regulate the second pump differential pressure P20 to a constant value. That is, when oil flows into the DR pulley Pu1, the limit valve 30 regulates the second pump differential pressure P20 to a constant value (= spring load pressure f (X1)) while restricting the fourth port P4. On the other hand, when the oil flows out from the DR pulley Pu1, the limit valve 30 opens the second port P2 and adjusts the pressure to a constant value (= spring load pressure f (X2)) while draining the oil to the reservoir 7. As a result, the torque increase (output increase) of the motor M can be suitably suppressed in a sudden shift state such as a sudden stop or kick-down. As a result, the motor M can be reduced in size.

  As described above, the hydraulic circuit 100 can perform quick gear ratio control such as a sudden stop or kick-down while miniaturizing the motor M that drives the second pump 20.

DESCRIPTION OF SYMBOLS 1 1st line 2 2nd line 3 3rd line 4 4th line 5 5th line 6 6th line 7 Reservoir 9 Check valve 10 1st pump 20 2nd pump 30 Limit valve (1st valve)
40 PDN regulator valve (second valve)
50 PDN solenoid valve (linear solenoid)
60 Clutch reducing valve (3rd valve)
100 Hydraulic circuit

Claims (7)

A first and second hydraulic device operating in a pair;
A first pump that constantly supplies a base hydraulic pressure that is at least required to drive the first and second hydraulic devices;
A second pump for alternately moving oil between the first and second hydraulic devices;
A first line connecting the first pump and the second hydraulic device;
A second line connecting the second pump and the first hydraulic device;
A third line connecting the second pump and the second hydraulic device;
A first valve that regulates the pressure regulation target to a constant value by balancing the force between the feedback pressure and the pilot pressure,
The first valve is disposed between the second pump and the second hydraulic device, takes in the pressure on the second hydraulic device side of the second pump as the feedback pressure, and uses the first hydraulic pressure as a pilot pressure. A hydraulic circuit for hydraulic equipment, which takes in the driving pressure of the equipment. The first valve is constituted by a valve body having irregularities formed on the outer peripheral surface, a body on which the valve body slides, and a spring that biases the valve body,
2. The hydraulic circuit for a hydraulic device according to claim 1, wherein a pressure on the second hydraulic device side of the second pump and a driving pressure of the first hydraulic device act on both shaft ends of the valve body, respectively. .   The first valve has a first oil passage and a second oil passage therein, a first valve position at which the valve body closes the first oil passage, and a second valve at which the valve body opens the second oil passage. The hydraulic circuit for hydraulic equipment according to claim 2, wherein the hydraulic circuit has a position.   The operating area of the valve body on which the pressure on the second hydraulic device side of the second pump acts and the operating area of the valve body on which the driving pressure of the first hydraulic device acts are equal to each other. Item 4. The hydraulic circuit for hydraulic equipment according to Item 2 or 3. A second valve that regulates the drive pressure of the second hydraulic device to the base hydraulic pressure by balancing the force of the feedback pressure and the pilot pressure;
A linear solenoid for supplying a pilot pressure related to the base hydraulic pressure to the second valve;
The hydraulic circuit for hydraulic equipment according to claim 1, further comprising a third valve that supplies an original pressure to the linear solenoid.   6. The hydraulic circuit for hydraulic equipment according to claim 1, wherein a fifth line for supplying the feedback pressure to the first valve is connected to the first line via a check valve.   The hydraulic circuit for a hydraulic device according to any one of claims 1 to 6, wherein the first and second hydraulic devices are a pair of pulley mechanisms.

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