JP3957664B2 - Hydraulic control device - Google Patents

Description

  The present invention relates to a hydraulic control device that operates two actuators simultaneously.

FIG. 4 shows a circuit diagram of a hydraulic control device used in a construction vehicle or the like.
As shown in the figure, switching valves 103 and 104 are connected to the traveling actuators 101 and 102. These switching valves 103 and 104 form inflow ports 105 and 106 connected to the variable pump P2, and relay ports 109 and 110 connected to the pressure compensation valves 107 and 108, respectively. The inflow ports 105 and 106 and the relay ports 109 and 110 communicate with each other regardless of whether the switching valves 103 and 104 are switched to the left or right. The opening degree of the variable throttles 111 and 112 formed in the communication process is proportional to the switching amount of the switching valves 103 and 104.

  The pressure compensation valves 107 and 108 are connected to the downstream side of the relay ports 109 and 110, and the first communication ports 113 and 114 and the second communication ports 115 and 116 are connected downstream of the pressure compensation valves 107 and 108. And connected to. These first and second communication ports 113 to 116 communicate with the tank passage 121 via the return ports 117 to 120 when the switching valves 103 and 104 are in the neutral position shown in the drawing.

When the switching valves 103 and 104 are switched to the left position in the drawing, the first communication ports 113 and 114 communicate with the first actuator ports 122 and 123, and the second actuator ports 124 and 125 return to the return ports 118 and 120. To the tank passage 121 via
When the switching valves 103 and 104 are switched to the right side position in the drawing, the second communication ports 115 and 116 communicate with the second actuator ports 124 and 125, and the first actuator ports 122 and 123 return to the return ports 117 and 119. To the tank passage 121 via

The switching valves 103 and 104 configured as described above include pilot pressure reducing valves (not shown) in the first pilot chambers 126 and 127 provided at the left end of the drawing and the second pilot chambers 128 and 129 provided at the right end of the drawing, respectively. Connected to.
This pilot pressure reducing valve guides the pilot pressure to the first pilot chambers 126 and 127 according to the direction in which the throttle lever (not shown) is tilted, and communicates the second pilot chambers 128 and 129 to the tank T2, or the second The pilot pressure is guided to the pilot chambers 128 and 129, and the first pilot chambers 126 and 127 are communicated with the tank T2.
The pilot pressure reducing valve can control the magnitude of the pilot pressure according to the operation amount of the throttle lever.

The variable pump P2 is connected to the regulator 130. The regulator 130 is configured to guide the highest load pressure among the load pressures of the actuators 101 and 102 selected by the shuttle valve 131.
The regulator 130 controls the discharge flow rate of the variable pump P2 so as to maintain the discharge pressure obtained by adding a constant pressure to the maximum load pressure.
A relief valve 132 is provided in the communication process between the shuttle valve 131 and the regulator 130.

The pressure compensation valves 107 and 108 communicate one of the pilot chambers 133 and 134 with the shuttle valve 131 via a load detection flow path 139. Therefore, the maximum load pressure is also led to the one pilot chamber 133, 134.
Further, the spring force of the springs 135 and 136 is applied to the one pilot chamber 133 and 134.

The other pilot chambers 137 and 138 facing the one pilot chamber 133 and 134 guide the pressure on the upstream side of the pressure compensation valves 107 and 108.
The pressure compensation valves 107 and 108 thus configured are values obtained by adding the pressure on the downstream side of the variable throttles 111 and 112 of the switching valves 103 and 104 to the pressure corresponding to the spring force of the springs 135 and 136 rather than the maximum load pressure. To control.

  By operating the pilot pressure reducing valve to introduce the pilot pressure to the first pilot chambers 126 and 127 of the switching valves 103 and 104, the switching valves 103 and 104 are switched to the left side position in the drawing. Accordingly, the pressure oil from the variable pump P2 is supplied to the actuators 101 and 102 via the first actuator ports 122 and 123, and the actuators 101 and 102 operate. Then, the return pressure oil from these actuators 101 and 102 is returned to the tank passage 121 via the second actuator ports 124 and 125.

  When the actuators 101 and 102 are operated as described above, the load pressure of the actuators 101 and 102 is guided to the load detection flow path 139. As described above, the maximum load pressure is selected by the shuttle valve 131 and is supplied to the regulator 130. Led. Then, the regulator 130 controls the discharge flow rate of the variable pump P2 so as to maintain the discharge pressure obtained by adding a certain pressure to the maximum load pressure.

Further, the maximum load pressure at this time is also led to one pilot chamber 133, 134 of the pressure compensation valve 107, 108. Therefore, the differential pressure before and after the variable throttles 111 and 112 of the switching valves 103 and 104 is kept constant.
When the pilot pressure is introduced into the second pilot chambers 128 and 129 of the switching valves 103 and 104 and the switching valves 103 and 104 are switched to the right side of the drawing, the supply side and the return side are opposite to the above. The explanation is omitted.

In the hydraulic control apparatus as described above, when the switching valves 103 and 104 are switched by the same amount, the operating speeds of the traveling actuators 101 and 102 become equal, so the vehicle travels straight.
However, since processing errors are inevitably generated in the switching valves 103 and 104, the pressure compensation valves 107 and 108, and other flow paths provided between the variable pump P2 and the actuators 101 and 102, the actuator 101 side and the actuator 102 are inevitably generated. Pressure loss is different on the side. In addition, since a difference occurs in the amount of oil leakage, the operating speeds of the actuators 101 and 102 are different. For this reason, there is a problem that even if the vehicle is driven straight, the vehicle turns.

In order to solve the above problem, an apparatus as shown in FIG. 5 is conventionally known.
As shown in FIG. 5, the switching valves 103 and 104 are provided with third communication ports 140 and 141 and fourth communication ports 142 and 143, respectively. The switching valves 103 and 104 are provided with full-speed traveling positions 103a, 104a and 103b, 104b, which are switching positions when the switching valves 103, 104 are fully switched.

The third communication ports 140 and 141 communicate with the first actuator ports 122 and 123 when the switching valves 103 and 104 are switched to the full speed travel positions 103a and 104a. On the other hand, the fourth communication ports 142 and 143 communicate with the second actuator ports 124 and 125 when the switching valves 103 and 104 are switched to the full speed travel positions 103b and 104b.
All of the third and fourth communication ports 140 to 143 configured as described above communicate with each other via the communication path 144.

  In the conventional apparatus as described above, when the switching valves 103 and 104 are switched to the full speed travel positions 103a and 104a, the opening degree of the variable throttles 111 and 112 is maximized, and the first actuator ports 122 and 123 are The three communication ports 140 and 141 and the communication path 144 communicate with each other. When the first actuator ports 122 and 123 communicate with each other, the amount of pressure oil supplied to the actuators 101 and 102 becomes equal. Therefore, the operating speeds of the traveling actuators 101 and 102 are equal, and the straight traveling performance of the vehicle can be ensured.

JP-A-8-338404 (pages 2 to 4, FIGS. 1 and 2)

  In the conventional hydraulic control apparatus shown in FIG. 5, when the switching valves 103 and 104 are switched to the full speed travel positions 103a and 104a, the switching valve 103 and the switching valve 104 communicate with each other. In this state, if there is a difference in the load that the actuator 101 and the actuator 102 receive from the outside, a pressure difference is generated between the actuators 101 and 102, so that a large amount of pressure oil is supplied to the actuator having a low pressure. Therefore, a difference occurs in the operating speed of the actuators 101 and 102.

  For example, when the vehicle travels on an inclined place as shown in FIG. For this reason, a pressure difference arises between the actuators 101 and 102, and much pressure oil will be supplied to the actuator 102 with a low pressure. Therefore, the operating speed of the actuator 102 becomes faster than the actuator 101, and the vehicle bends toward the actuator 101 side.

  Further, even if an attempt is made to supply more pressure oil to the actuator 101 in order to correct the vehicle from turning, the pressure oil supplied to the actuator 102 further increases because the pressure of the actuator 102 is low. Therefore, further bending to the actuator 101 side is further promoted.

In other words, the conventional device can ensure straightness when traveling on flat ground, but when traveling on an inclined ground as shown in FIG. 3, that is, when the load difference between the actuator 101 and the actuator 102 is large. Had the problem that the vehicle would turn.
An object of the present invention is to provide a hydraulic control device capable of setting both actuators to operating speeds according to lever operations when there is a difference in load received by two actuators from the outside.

According to a first aspect of the present invention, there is provided a first supply circuit that guides pressure oil of a pressure supply source to a first actuator, a second supply circuit that guides pressure oil of a pressure supply source to a second actuator, and switching provided in both the supply circuits. A valve, a pressure compensation valve provided on the downstream side of the switching valve, a communication path communicating the most downstream side of the first supply circuit and the most downstream side of the second supply circuit, and a communication provided in the communication path And the communication valve is configured such that when the difference between the load pressure of the first supply circuit and the load pressure of the second supply circuit is equal to or less than a set pressure, the first supply circuit and the second supply are connected via the communication passage. The circuit is connected, and when the set pressure is exceeded, the communication between the first supply circuit and the second supply circuit is cut off.

The second invention is a communication valve having a communication position communicating with the first supply circuit and a second supply circuit, and a blocking position for blocking the communication between the first supply circuit and a second supply circuit, this The communication valve is provided with a first pilot chamber and a second pilot chamber, and is provided with urging means having equal urging forces on the first pilot chamber side and the second pilot chamber side, so that the first supply is supplied to the first pilot chamber. A first pilot passage that guides the load pressure of the circuit, a second pilot passage that guides the load pressure of the second supply circuit to the second pilot chamber, and a communication passage on the first pilot passage and the second pilot passage. A difference between a load pressure of the first supply circuit led to the first pilot chamber and a load pressure of the second supply circuit led to the second pilot chamber is the biasing means. When the urging force is less than Chi, communicates the first supply circuit and a second supply circuit, when it exceeds the biasing force, characterized in that blocking switched communication valve is in the shutoff position, the communication between the first supply circuit and the second supply circuit And

According to the first and second aspects of the present invention, when the difference in load pressure between the first supply circuit and the second supply circuit is equal to or less than the set pressure, the first supply circuit and the second supply are provided by the communication valve provided in the communication path. The circuit communicates with the first supply circuit and the second supply circuit when the set pressure is exceeded. Accordingly, when the pressure difference between the first and second actuators exceeds the set pressure due to the difference in load received from the outside by the first actuator and the second actuator, the pressure oil supplied to the first and second actuators Therefore, the first and second actuators can be set to operating speeds corresponding to lever operations.
Further, by connecting one end of the communication path to the most downstream side of the first supply circuit and connecting the other end to the most downstream side of the second supply circuit, the distance between the communication path and the first and second actuators is shortened. is doing. Therefore, since the influence of pressure loss, oil leakage, etc. between the communication path and the first and second actuators is small, the loads on the first and second actuators can be accurately detected.

  In particular, according to the second aspect of the invention, the throttle is provided between the first pilot passage and the second pilot passage on the communication passage, so that the supply passage communicates with the supply passage, and pressure oil is passed through the communication passage. When flowing, the pressure oil can be prevented from flowing abruptly. Since the rapid flow of pressure oil can be suppressed, vibration associated with the rapid flow of pressure oil does not occur. Therefore, vibration of the device itself can be suppressed.

1 to 3 show circuit diagrams of a hydraulic control apparatus according to an embodiment of the present invention.
As shown in the figure, the discharge path 3 is provided in the variable pump P which is a pressure supply source of the present invention, and the discharge path 3 is branched into a first supply path 4a and a first supply path 5a.
Further, a switching valve 6 is provided in the first supply path 4a, and a switching valve 7 is provided in the first supply path 5a. The downstream supply path of the switching valve 6 is a second supply path 4b, and the downstream supply path of the switching valve 7 is a second supply path 5b.
The first supply path 4a and the second supply path 4b constitute the first supply circuit of the present invention, and the first supply path 5a and the second supply path 5b provide the second supply of the present invention. The circuit is configured.

  Further, the first actuator 1 for traveling is connected to the first supply path 4a via the second supply path 4b, and the first supply path 5a is connected to the first supply path 5a via the second supply path 5b. 2 The actuator 2 is connected. Therefore, the pressure oil from the variable pump P is supplied to the first and second actuators 1 and 2 via the first and second supply paths 4a and 4b and the first and second supply paths 5a and 5b.

Pressure compensation valves 8 and 9 are provided in the second supply passages 4b and 5b. In the first pilot chambers 8 a and 9 a of the pressure compensation valves 8 and 9, the highest load pressure among the load pressures of the first and second actuators 1 and 2 is passed through the first pilot passages 11 and 12. Guided.
Further, springs 18 and 19 having the same spring force are provided on the first pilot chambers 8a and 9a side of the pressure compensation valves 8 and 9, respectively.

On the other hand, the pressure on the downstream side of the switching valves 6 and 7 is guided to the second pilot chambers 8b and 9b of the pressure compensation valves 8 and 9 via the second pilot passages 14 and 15, respectively.
Therefore, each pressure compensating valve 8, 9 is a value obtained by adding the upstream pressure, that is, the downstream pressure of each switching valve 6, 7, to the maximum load pressure plus the pressure corresponding to the spring force of springs 18, 19. Keep its opening so as to maintain.

The maximum load pressure of the first and second actuators 1 and 2 is selected by the shuttle valve 10. The maximum load pressure selected by the shuttle valve 10 is led from the pilot passage 13 to the first pilot chambers 8a, 9a of the pressure compensation valves 8, 9 through the first pilot passages 11, 12.
The maximum load pressure selected by the shuttle valve 10 is also led to the regulator 17 via the pilot passage 16. The regulator 17 controls the discharge flow rate of the variable pump P so as to maintain a discharge pressure obtained by adding a constant pressure to the maximum load pressure.

Further, the second supply path 4b and the second supply path 5b communicate with each other through the communication path 20, and a communication valve 21 is provided in the communication path 20. This communication valve 21 shuts off the communication between the communication position A that connects the second supply path 4b and the second supply path 5b via the communication path 20, and the communication between the second supply path 4b and the second supply path 5b. It consists of positions B and C.
A pressure on the first actuator 1 side is guided to the first pilot chamber 21 a of the communication valve 21 via the first pilot passage 22. On the other hand, the pressure on the second actuator 2 side is guided to the second pilot chamber 21 b of the communication valve 21 via the second pilot passage 23.

  At both ends of the communication valve 21, springs 24 and 25 having the same spring force are provided. Therefore, the communication valve 21 does not move from the illustrated communication position A when the difference between the pressure on the first actuator 1 side and the pressure on the second actuator 2 side is less than the set pressure of the springs 24 and 25. The 2nd supply path 4b and the 2nd supply path 5b are connected.

  On the other hand, when the difference between the pressure on the first actuator 1 side and the pressure on the second actuator 2 side exceeds the set pressure of the springs 24 and 25, the communication valve 21 changes from the communication position A to the cutoff position B or the cutoff position C. Thus, the communication between the second supply path 4b and the second supply path 5b is cut off.

  Note that the pressure difference between the first actuator 1 side and the second actuator 2 side necessary for switching the communication valve 21 is determined by the set pressure of the springs 24 and 25. Therefore, if the set pressure of the springs 24 and 25 is changed, the pressure difference required for switching the communication valve 21 can also be changed.

  The communication valve 21 is provided with a throttle 26. When the second supply passage 4b and the second supply passage 5b communicate with each other through the throttle 26 and pressure oil flows through the communication passage 20, the rapid flow of the pressure oil can be suppressed. Since the rapid flow of pressure oil can be suppressed, vibration associated with the rapid flow of pressure oil does not occur. Therefore, vibration of the device itself can be suppressed.

  The first supply path 4a, the switching valve 6, the second supply path 4b, and the pressure compensation valve 8 constitute a first circuit of the present invention. The first supply path 5a, the switching valve 7, the second supply path 5b, and the pressure compensation valve 9 constitute a second circuit of the present invention.

The pressure oil discharged from the variable pump P is guided to the first supply paths 4 a and 5 a via the discharge path 3. The pressure oil guided to the first supply path 4 a is supplied to the first actuator 1 through the switching valve 6 → the second supply path 4 b → the pressure compensation valve 8. On the other hand, the pressure oil guided to the first supply path 5 a is supplied to the second actuator 2 through the switching valve 7 → the second supply path 5 b → the pressure compensation valve 9.

  At this time, since the maximum load pressure is applied to the first pilot chambers 8a and 9a of the pressure compensation valves 8 and 9, the pressure upstream of the pressure compensation valves 8 and 9, that is, the switching valves 6 and 9, respectively. 7 is maintained at a value obtained by adding the pressure corresponding to the spring force of the springs 18 and 19 to the maximum load pressure.

  On the other hand, the pressure on the upstream side of the switching valves 6 and 7 is maintained by the variable pump P at a value obtained by adding a constant pressure to the maximum load pressure. Therefore, the pressure difference between the upstream and downstream of each switching valve 6, 7, that is, the pressure difference before and after each switching valve 6, 7 becomes equal. Therefore, when the switching valves 6 and 7 are switched, a flow rate corresponding to the opening degree is supplied to the first and second actuators 1 and 2 via the second supply paths 4b and 5b. become.

At this time, if the difference between the pressure on the first actuator 1 side and the pressure on the second actuator 2 side is equal to or less than the set pressure of the springs 24 and 25, the communication valve 21 does not move from the illustrated communication position A. The second supply path 4 b and the second supply path 5 b communicate with each other through the communication path 20.
On the other hand, when the difference between the pressure on the first actuator 1 side and the pressure on the second actuator 2 side exceeds the set pressure of the springs 24 and 25, the communication valve 21 is switched to the cutoff position B or C, and the second supply The communication between the path 4b and the second supply path 5b is blocked.

According to the above-described embodiment, the communication between the second supply path 4b and the second supply path 5b is cut off, so that the first and second actuators 1 and 2 depend on the load received from the outside by the first actuator 1 and the second actuator 2. Even if there is a pressure difference between the actuators 1 and 2, a large amount of pressure oil is not supplied to the actuator with a low pressure. That is, since the amount of pressure oil supplied to the first and second actuators 1 and 2 is substantially equal, the first actuator 1 and the second actuator 2 can be set to operating speeds corresponding to lever operations.
Therefore, even if the vehicle using the above-described device travels on a sloping ground as shown in FIG. 3, the operating speeds of the first and second actuators 1 and 2 are equal, so that the straightness of the vehicle can be ensured.

In the above embodiment, the throttle 26 is provided in the communication valve 21. However, the throttle 26 is provided on the communication path 20 and between the first pilot path 22 and the second pilot path 23. Good.
For example, as shown in FIG. 2, if the throttle 26 is provided in the communication path 20, the communication valve 21 can be reduced in size by the space of the throttle 26.

  As shown in FIGS. 1 and 2, the communication path 20 has one end connected to the most downstream side of the second supply path 4b and the other end connected to the most downstream side of the second supply path 5b. Although the 2 supply path 4b and the 2nd supply path 5b are connected, as long as the 2nd supply path 4b and the 2nd supply path 5b are connected, they may be connected anywhere.

  However, as in this embodiment, if the most downstream side of the second supply path 4b communicates with the most downstream side of the second supply path 5b, the communication path 20 and the first and second actuators 1 and 2 are connected. The distance becomes shorter. Accordingly, since the influence of pressure loss and oil leakage between the communication path and the first and second actuators 1 and 2 is small, the load on the first and second actuators 1 and 2 can be accurately detected. .

In this embodiment, a traveling actuator is used as the two actuators 1 and 2, but any actuator may be used.
For example, there is a theater stage device that moves up and down the stage by two cylinder actuators. If the hydraulic control device of the present invention is used for the cylinder actuator of such a stage device, even if a biased force is applied to the stage device, the operating speeds of the two cylinder actuators are almost equal. You can move up and down.

Further, in this embodiment, the springs 18 and 19 provided on the first pilot chamber 21a side and the second pilot chamber 21b side of the communication valve 21 are used as the biasing means of the present invention. May be used as the biasing means. That is, as long as the urging force is applied to the communication valve 21, the means is not limited to the spring. Further, the urging force of the urging means may be variably controlled.
In this embodiment, a load sensing circuit that operates two actuators with one variable pump is used, but two variable pumps may be connected to the two actuators.

It is a circuit diagram showing a first embodiment. It is a circuit diagram which shows 2nd Embodiment. It is a figure which shows the vehicle which drive | works a slope. It is a circuit diagram which shows the conventional hydraulic control apparatus. It is the figure which provided the communicating path in the hydraulic control apparatus of FIG.

Explanation of symbols

1, 2 1st, 2nd actuator 4a, 5a 1st supply path 4b, 5b 2nd supply path 6, 7 Switching valve 8, 9 Pressure compensation valve 20 Communication path 21 Communication valve 21a 1st pilot chamber 21b 2nd pilot chamber 22 1st pilot passage 23 2nd pilot passage 24,25 Spring 26 Restriction P Variable pump

Claims (2)

A first supply circuit for introducing pressure oil of the pressure supply source to the first actuator; a second supply circuit for introducing pressure oil of the pressure supply source to the second actuator; a switching valve provided in the both supply circuits; comprising a pressure compensating valve provided on the downstream side, and the communication passage connecting the downstream side of the most downstream side and the second supply circuit of the first supply circuit, and a communication valve provided in the communication passage, the The communication valve communicates the first supply circuit and the second supply circuit via the communication path when the difference between the load pressure of the first supply circuit and the load pressure of the second supply circuit is equal to or less than the set pressure. A hydraulic control device that shuts off communication between the first supply circuit and the second supply circuit when the set pressure is exceeded. A communication position to communicate the first supply circuit and a second supply circuit, a communication valve and a blocking position for blocking the communication between the first supply circuit and a second supply circuit, this communication valve first A pilot chamber and a second pilot chamber are provided, and biasing means having the same biasing force are provided on the first pilot chamber side and the second pilot chamber side, and the load pressure of the first supply circuit is guided to the first pilot chamber. A first pilot passage, a second pilot passage for guiding the load pressure of the second supply circuit to the second pilot chamber, a throttle provided on the communication passage and between the first pilot passage and the second pilot passage; And the difference between the load pressure of the first supply circuit led to the first pilot chamber and the load pressure of the second supply circuit led to the second pilot chamber is less than or equal to the biasing force of the biasing means , communication valve is maintaining the communicating position, the first supply Communicates the road and a second supply circuit, when it exceeds the biasing force, switches the communication valve is in the shutoff position, the hydraulic control device according to claim 1, wherein for blocking the communication between the first supply circuit and the second supply circuit .

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