JPH04105203U - hydraulic control device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a hydraulic control device that can prevent operating speed from varying due to the influence of load pressure acting on a reciprocating hydraulic actuator. [Configuration] The pilot type directional flow control valves 25, 45 and the differential pressures (P1-P2) and (P3) before and after the control valves 25, 45 are connected to the supply lines 4 and 5 that supply hydraulic pressure to the reciprocating hydraulic actuators 20 and 40, respectively. -P4) to set values ΔP1, ΔP
2, check valves 28, 43, 48 are installed in the oil lines 24, 41, 42 that connect the ports 22a, 40a, 40b on which load pressure acts to the control valves 25, 45. and meter-out pressure compensation valves 29, 44, and 49 are provided in parallel to control the meter-out flow rate to match the meter-in flow rate. Incidentally, when the plurality of hydraulic actuators are operated, the anti-saturation signal pressure AS is used to restrict the flow rate and perform deceleration control.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a hydraulic control device, and in particular to the operating speed of a reciprocating hydraulic actuator. This relates to a device that prevents fluctuations due to the influence of load pressure.

0002

[Conventional technology]

In construction machinery and civil engineering machinery, multiple reciprocating hydraulic pumps can be used from one hydraulic pump. It supplies hydraulic pressure to actuators (hydraulic motors, double-acting hydraulic cylinders, etc.) and Supply pilot pressure from the hydraulic operation valve to the directional flow control valve for each hydraulic actuator. to operate the hydraulic actuator.

For example, FIG. 2 shows a part of the hydraulic system installed in a hydraulic excavator, in which a hydraulic pump 1 is provided with a regulator 7 and a control valve 8 for tilting angle control, and supports a driver's cab. A swing hydraulic motor 40 for swinging the swing table and a boom hydraulic cylinder 20 for swinging the boom up and down are provided, and the hydraulic pressure supply line 5 to the hydraulic motor 40 is connected to a pair of ports of the hydraulic motor 40. A control valve 45 is provided to control the direction and flow rate of hydraulic pressure supplied to the supply line 5 on the upstream side of the control valve 45, and the differential pressure between the inlet and the outlet of the control valve 45 ^is set to a set value (for example, 20 kg/cm ), and the supply line 4 to the hydraulic cylinder 20 is provided with a meter-in pressure compensation valve 47 that controls the direction and flow rate for selectively supplying hydraulic pressure to a pair of ports of the hydraulic cylinder 20. A meter-in pressure compensation is provided in which a control valve 25 is provided and the pressure is compensated in the supply line 4 on the upstream side of the control valve 25 so that the differential pressure between the inlet and the outlet of the control valve 25 becomes a set value (for example, 20 kg/cm ² ). A valve 27 is provided so that pilot pressures p1i, p2i can be supplied from the hydraulically operated valve to the control valve 25 via the pilot line, and pilot pressures p3i, p4i can be supplied to the control valve 45 via the pilot line, Further, the anti-saturation signal pressure AS for flow rate restriction is supplied from the signal pressure line to the meter-in pressure compensating valves 29 and 47, respectively, and the one with the larger outlet side oil pressure of the control valves 25 and 45 is the shuttle valve 6. The hydraulic pressure and discharge pressure are supplied to the control valve 8 via the control valve 8, and the regulator 7 is operated via the control valve 8.

0004 Here, for example, when swinging the boom upward, the head of the hydraulic cylinder 20 is The hydraulic pressure in the rod chamber 21 is discharged while supplying hydraulic pressure to the chamber 22, but the inlet of the control valve 25 The differential pressure between the Since the flow rate flowing into the door chamber 22 is maintained at a constant value determined by the pilot pressure p1i, The rod of the hydraulic cylinder 20 extends at a constant speed. The same applies to the hydraulic motor 40, and the pilot pressure p4i is applied to the hydraulic motor 40 via the control valve 45. Since a fixed flow rate of hydraulic pressure is supplied to one port of the hydraulic motor 40, the hydraulic pressure Motor 40 rotates at a constant speed.

[0005] Here, anti-saturation is applied to the pressure compensation valves 27 and 47 to limit the flow rate. When the signal pressure AS is supplied, each pressure compensation valve 27, 47 has a smaller differential pressure. Since the flow rate is controlled in such a way that the flow rate to the hydraulic motor 40 and the hydraulic cylinder 20 is decreases and enters a deceleration state.

[0006]

[Problem that the idea aims to solve]

In the hydraulic control device shown in FIG. 2, for example, if dirt is collected in the bucket of a hydraulic excavator, When the boom is swung downward while the head chamber 22 is When the load pressure due to the weight of When this occurs, the meter-out flow rate from the head chamber 22 increases, causing the rod to retract. The entry speed increases significantly, causing the boom to run away. At this time, the oil in the rod chamber 21 When the pressure difference between the inlet and outlet of the control valve 25 starts to increase as the pressure decreases, the pressure difference Although the pressure compensation valve 27 controls the flow rate to decrease so as to maintain the set value, Since cavitation has occurred in the meter-in chamber 21, the meter-in pressure compensating valve is The pressure compensation control by No. 27 does not function effectively at all.

[0007] Anti-saturation signal pressure AS is input while the hydraulic motor 40 is rotating at full speed. When the meter-in flow rate to the hydraulic motor 40 is significantly reduced and the rotating base suddenly decelerates, Also, since the rotational inertia of the swivel table acts, the meter-in pressure compensating valve is The pressure compensation control of No. 47 will not function effectively, causing the swivel base to run away. In this way, in hydraulic systems where the load pressure due to gravity and inertia force is quite large, When discharging a load pressure of It is almost impossible to control the operating speed of the motor to a desired speed.

[0008] The purpose of this invention is to reduce the impact of the load pressure acting on a reciprocating hydraulic actuator. A hydraulic control device that can prevent the operating speed of a hydraulic actuator from fluctuating due to The goal is to provide the following.

[0009]

[Means to solve the problem]

The hydraulic control device according to claim 1 provides a reciprocating flow from a hydraulic supply line connected to a hydraulic supply source. The direction and flow rate for selectively supplying hydraulic pressure to a pair of ports on a dynamic actuator can be determined externally. A control valve that is controlled by pilot pressure from Controls the flow rate so that the differential pressure between the inlet and outlet of the control valve installed in the supply line is the set value. In a hydraulic control device equipped with a meter-in pressure compensation valve, the hydraulic actuator Connect at least the port on which load pressure acts among the pair of ports of the motor to the control valve. A check valve that allows hydraulic pressure to flow to that port, and a control valve inlet and outlet. and a meter-out pressure compensation valve that controls the flow rate so that the differential pressure of They are installed in parallel.

0010 The hydraulic control device according to claim 2 is the hydraulic control device according to claim 1, in which a plurality of Multiple sets of control valves and meter-in pressure for each reciprocating hydraulic actuator A force compensation valve and a meter-out pressure compensation valve are installed, and these multiple meter-in pressure Compensation valves and multiple meter-out pressure compensation valves are connected to each hydraulic actuator. Anti-saturation signal pressure supplied externally when limiting tine flow rate , respectively, to reduce each of the differential pressures.

[0011]

[Effect] In the hydraulic control device according to claim 1, the meter-in pressure compensation valve is a control valve. The flow rate is controlled so that the differential pressure between the inlet and outlet of the The meter-in flow rate flowing from the valve to the reciprocating hydraulic actuator is determined by the pilot pressure. The hydraulic actuator is controlled to a completely constant value, and the operating speed of the hydraulic actuator is controlled to be constant. Of the pair of ports of the hydraulic actuator, at least the port on which load pressure acts The oil line that connects the port to the control valve has a check valve that allows hydraulic pressure to flow to that port. , a meter-out that compensates for pressure so that the differential pressure between the inlet and outlet of the control valve is equal to the differential pressure. Since the hydraulic pressure compensation valve is installed in parallel, hydraulic pressure is supplied to the port where this load pressure acts. A constant meter-in flow is supplied through the check valve when The actuator operates at a constant speed. By the way, is this the port where the load pressure acts? When discharging hydraulic pressure from the control valve, the meter-out pressure compensation valve connects the inlet and outlet of the control valve. Since the meter-out flow rate is controlled so that the differential pressure is at the set value, the meter-in flow rate is The meter is controlled so that the flow rate is constant and the flow rate is constant and matches the meter-in flow rate. The out flow rate will be controlled. In this way, the port where load pressure acts When discharging hydraulic pressure from It can be controlled to a constant speed. Therefore, the operating speed of the reciprocating hydraulic actuator in the forward direction and the backward direction It is possible to precisely control the operating speed of the It can be controlled.

0012 In the hydraulic control device according to claim 2, basically the same effect as in claim 1 can be obtained. It will be done. In addition, multiple sets of control valves each corresponding to multiple reciprocating hydraulic actuators, A meter-in pressure compensation valve and a meter-out pressure compensation valve are installed, and these multiple -tine pressure compensation valve and multiple meter-out pressure compensation valves are attached to each hydraulic actuator. Externally supplied anti-saturation when limiting the meter-in flow to the Since the configuration is configured to receive each of the signal pressures and reduce each of the differential pressures, the external When more anti-saturation signal pressure is input, the For the corresponding meter-in pressure compensation valve and meter-out pressure compensation valve, the corresponding control Since the pressure difference between the inlet and outlet of the valve is controlled to decrease, each hydraulic actuator Deceleration control according to anti-saturation signal pressure during both forward and backward movements This will ensure that the process is performed accurately.

[0013]

[Effect of the idea]

According to the hydraulic control device according to claim 1, as explained in the section of the operation, the control By installing a valve and a meter-in pressure compensation valve, the meter-in flow rate can basically be kept constant. The operating speed of the hydraulic actuator can be controlled at a constant level, and the load pressure can be A check valve and meter-out pressure compensation are installed in the oil line connecting the active port to the control valve. By installing compensation valves in parallel, when hydraulic pressure is discharged from the port where load pressure acts, When the meter-out pressure compensation valve adjusts the meter-in flow rate to match the meter-in flow rate. It is possible to control the output flow rate and keep the operating speed of the hydraulic cylinder constant. This means that even when load pressure is applied, the hydraulic actuator's forward speed and It is possible to precisely control the double-acting speed, and the operating speed during deceleration can also be precisely controlled. You can control it.

[0014] According to the hydraulic control device according to claim 2, as explained in the section of the operation, the basic In other words, the same effects as in claim 1 can be obtained. In addition, for each of the multiple reciprocating hydraulic actuators, the Accurately performs deceleration control according to the anti-saturation signal pressure even during reverse operation. I can do it.

[0015]

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the hydraulic system of the present invention is applied to a part of the hydraulic system of a hydraulic excavator as a construction machine. This is an example when a control device is applied. As shown in Figure 1, a boom that drives the swash plate hydraulic pump 1 and the boom to swing up and down. hydraulic cylinder 20 and a swivel that drives the swivel base including the driver's cab in forward and reverse rotation around a vertical axis. A recirculating hydraulic motor 40 is provided. The first supply line 4 that supplies hydraulic pressure from the hydraulic pump 1 to the hydraulic cylinder 20 is filled with oil. A direction in which hydraulic pressure is alternatively supplied to the rod chamber 21 and head chamber 22 of the pressure cylinder 20 and a pilot control valve 25 that controls the flow rate, a check valve 26, and a meter-in valve. A pressure compensating valve 27 is interposed as shown, and the head chamber 2 of the hydraulic cylinder 20 1 has a fairly large load due to the weight of the earth and sand loaded into the bucket at the tip of the boom. Since load pressure acts on the oil passage 2 leading from the port 22a of the head chamber 22 to the control valve 25, 4 includes a check valve 28 that allows oil pressure to be supplied to the head chamber 22, and a meter-out pressure A force compensation valve 29 is provided in parallel. Note that the port 21a of the rod chamber 21 is It is connected via line 23 to control valve 25 .

[0016] The control valve 25 has a first position where hydraulic pressure is supplied to the rod chamber 21 and a first position where hydraulic pressure is supplied to the head chamber 22. switchable between a second position for supplying hydraulic pressure and a blocking position for blocking hydraulic pressure; Moreover, the opening degree is connected from the first position to the block position and from the second position to the block position. It is a spool valve that changes continuously, and the pilot valve is supplied from the hydraulically operated valve in the driver's seat. The position is switched by the pilot pressure p1i, p2i, and the pilot pressure p1i or the pilot pressure It is operated to an opening degree according to the pilot pressure p2i.

The meter-in pressure compensation valve 27 is a spool valve that can be switched between a supply position and a block position and whose opening degree changes continuously from the supply position to the block position, The flow rate is controlled so that the differential pressure (P1-P2) between the inlet side oil pressure P1 and the outlet side oil pressure P2 becomes a set pressure ΔP1 (for example, 20 kg/cm ² ) set by the spring 27a. Therefore, the inlet side oil pressure P1 of the control valve 25 is introduced into the pilot part 27b through the oil passage 30, and the outlet side oil pressure P2 of the control valve 25 is introduced into the pilot part 27c through the oil passage 31. An anti-saturation signal pressure AS generated by a signal pressure generator (not shown) is supplied to the pilot section 27d for uniformly restricting the flow rate to the hydraulic actuators when the actuators are operated simultaneously.

[0018] The meter-out pressure compensation valve 29 receives hydraulic pressure from the head chamber 22 where the load pressure acts. To prevent the meter-out flow rate from becoming abnormally large due to the influence of load pressure when discharging. In order to make the meter-out flow rate compatible with the meter-in flow rate supplied to the rod chamber 21. Similarly to the meter-in pressure compensation valve 27, the inlet side oil pressure P1 of the control valve 25 The differential pressure (P1-P2) between the pressure and the outlet side oil pressure P2 is the set pressure ΔP1 set by the spring 29a. This is to control the meter-out flow rate of the oil passage 24 so that the meter-in flow rate is It has the same structure as the pressure compensation valve 27. Therefore, the inlet oil pressure P1 of the control valve 25 is supplied to the pilot part 29b through the oil passage 32. Also, the outlet side oil pressure P2 of the control valve 25 is introduced into the pilot part 29c through the oil passage 3. 3, and an anti-saturation signal pressure is also introduced to the pilot section 29d. AS has been introduced.

[0019] A second supply line 5 that supplies hydraulic pressure from the hydraulic pump 1 to the hydraulic motor 40 includes a front A pilot type control valve 45 having the same configuration as the control valve 25 described above, a check valve 46, and a front A meter-in pressure compensation valve 47 having the same configuration as the meter-in pressure compensation valve 27 described above is provided. As shown in the figure, the hydraulic motor 40 is installed on the swivel base when decelerating from the swivel state. The load pressure due to the rotational inertia of is applied to one of the forward rotation port 40a and the reverse rotation port 40b. Therefore, the oil passage 41 connecting the normal rotation port 40a to the control valve 45 has a Similar to the check valve 28 and the meter-out pressure compensation valve 29, the check valve 43 and the meter-out pressure compensating valve 44 are connected in parallel, and the reversing port 40b is connected in parallel. Similarly to the above, the oil passage 42 connected to the control valve 45 has a check valve 48 and a meter out. A pressure compensation valve 49 is connected in parallel.

The control valve 45 is switched in position by pilot pressures p3i and p4i supplied from hydraulically operated valves, and is operated to an opening degree according to the pilot pressures p3i and p4i. The meter-in pressure compensation valve 47 adjusts the pressure difference (P3-P4) between the inlet side oil pressure P3 and the outlet side oil pressure P4 of the control valve 45 to a set pressure ΔP2 (for example, 20 kg/cm ² ) set by a spring 47a. The inlet oil pressure P3 is introduced into the pilot part 47b through an oil passage 50, the outlet oil pressure P4 is introduced into the pilot part 47c through an oil passage 51, and the anti-saturation signal pressure is introduced into the pilot part 47d. AS has been introduced.

[0021] Each meter-out pressure compensation valve 44 and 49 has the same structure as the pressure compensation valve 29. The springs 44a and 49a, which are similar to the spring 29a, are used to obtain the same function. The inlet side oil passage P3 connects the oil passages 52 and 53 to the pilot parts 44b and 49b. The outlet side oil pressure P4 is introduced into the pilot parts 44c and 49c through the oil passage 54. An anti-saturation signal is introduced into the pilot sections 44d and 49d. Pressure AS has been introduced.

[0022] Furthermore, a hydraulic series is used as a tilt angle regulator to control the discharge amount of the hydraulic pump 1. A hydraulic pressure P2 on the outlet side of the control valve 25 is connected to an oil passage 31 and an oil passage. 34 to the shuttle valve 6, and the outlet side oil pressure P4 of the control valve 45 is supplied to the oil path. 51 and oil passage 55 to the shuttle valve 6, and the shuttle valve 6 receives hydraulic pressures P2 and P. 4 is selected and supplied to the control valve 8 via the oil path 60, and also to the hydraulic pump. The discharge pressure of the pump 1 is supplied to the control valve 8 via an oil passage 61.

[0023] Next, the operation of the hydraulic control device for the hydraulic excavator described above will be explained. For example, when the pilot pressure p1i is supplied, the control valve 25 is switched to the second position. Then, hydraulic pressure is supplied to the head chamber 22 through the check valve 28 of the oil passage 24, and the oil passage Hydraulic pressure in the rod chamber 21 is discharged via 23. At this time, the differential pressure (P1-P2) is set by the meter-in pressure compensation valve 27. Since the pressure is controlled to be ΔP1, the flow inside the control valve 25 is supplied to the head chamber 22. The flow rate is a constant value determined by the pilot pressure p1i, and the operation of the hydraulic cylinder 20 is The moving speed is controlled to be constant. When anti-saturation signal pressure AS is input , by the biasing force of the anti-saturation signal pressure by the pressure compensation valve 27. Control is performed so that the differential pressure (P1-P2) is smaller than the set pressure ΔP1. Therefore, the meter-in flow rate flowing through the control valve 25 decreases and the operating speed of the hydraulic cylinder 20 decreases. degree is reduced.

[0024] In contrast, the pilot pressure p2i is supplied to supply hydraulic pressure to the rod chamber 21. When the load pressure is applied to the head chamber 22, if the meter out If the head pressure compensation valve 29 is not provided, the load pressure will cause the head chamber 22 to The discharged meter-out flow rate becomes abnormally large, causing a cavity in the rod chamber 21. tion occurred, the operating speed of the hydraulic cylinder 20 became abnormally high, and the boom escaped. do. However, a meter-out pressure compensation valve 29 is provided, and this pressure compensation valve 29 The meter-out flow rate is controlled so that the differential pressure (P1-P2) becomes the set pressure ΔP1. Since the operating speed of the hydraulic cylinder 20 starts to increase and the rod chamber 21 decreases and the differential pressure (P1-P2) begins to increase, the pressure compensation valve 29 opens Change to the decreasing side and reduce the meter-out flow rate. In this way, the pilot The meter-out flow rate is compatible with or corresponds to the meter-in flow rate according to the pressure p2i. The meter-out flow rate is controlled so that the operating speed of the hydraulic cylinder 20 is constant. It will be held constant. When anti-saturation signal pressure AS is input In some cases, control is performed so that the differential pressure is smaller than the set differential pressure ΔP1 as described above, The meter-in flow rate and meter-out flow rate decrease, and the operating speed of the hydraulic cylinder 20 increases. Slowed down.

[0025] Next, a control valve 45 for the hydraulic motor 40 and a meter-in pressure compensation valve 47 and The functions of the meter-out pressure compensation valves 44 and 49 are basically the same as above. Therefore, I will briefly explain it. When the pilot pressure p4i is supplied, the control valve 45 is switched to the first position and the control valve 45 is switched to the first position. Hydraulic pressure is supplied to the forward rotation port 40a through the check valve 43, and the reverse rotation port 40b. Hydraulic pressure is discharged from the meter-out pressure compensation valve 49. At this time, the above Similarly, the meter-in flow rate is controlled to a constant value determined by the pilot pressure p4i, and the pressure compensation The compensation valve 49 controls the meter-out flow rate to be equal to the meter-in flow rate. , the hydraulic motor 40 rotates forward at a constant speed.

[0026] Here, if the anti-saturation signal pressure AS is supplied, The meter-in flow rate is controlled to decrease. However, if the pressure compensation valve 49 If it is not provided, the hydraulic motor 40 will not rotate due to the rotational inertia of the swivel base. The swivel base runs away when trying to rotate at the rotational speed. However, by providing a pressure compensation valve 49, Since the meter-out flow rate is controlled to be equal to the meter-in flow rate, the Meter-in flow rate and meter-out flow rate are simultaneously controlled by chisaturation signal pressure AS. Therefore, the deceleration of the hydraulic motor 40 is performed reliably and accurately. . In addition, also when the pilot pressure p3i is supplied and the hydraulic motor 40 is reversed. Same as above.

[0027] As explained above, the meter-out pressure compensation valve 29 and check valve 28 are provided. As a result, the meter-out flow rate is abnormal due to the load pressure acting on the head chamber 22. It is possible to prevent the boom from escaping by increasing the The operating speed in the forward and reverse directions can be accurately and stably controlled. In addition, meter-out pressure compensation valves 44 and 49 and check valves 43 and 48 are installed. deceleration with or without anti-saturation signal pressure AS. It is possible to prevent the swivel base from running away due to the rotational inertia of the swivel base etc. when Correct the rotation speed when decelerating the hydraulic motor 40 during forward rotation and reverse rotation. It can be controlled reliably and stably.

[0028] The hydraulic control device of the present invention is compatible with other reciprocating hydraulic actuators of hydraulic excavators. It can be similarly applied to hydraulic circuits for hydraulic excavators, and can also be applied to various types of construction other than hydraulic excavators. For reciprocating hydraulic actuators for machinery, civil engineering machinery, and various other industrial machinery and equipment. Of course, the present invention can also be similarly applied to hydraulic circuits.

[0029]

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a hydraulic control device for a hydraulic excavator according to an embodiment of the present invention.

FIG. 2 is a diagram corresponding to FIG. 1 according to the prior art.

[Explanation of symbols]

1. Hydraulic pump 4. Supply line 5. Supply line 20...Hydraulic cylinder 21a...port 22a...port 24...Oil road 25...Pilot control valve 27...Pressure compensation valve for meter-in 28...Check valve 29...Pressure compensation valve for meter out 40...Hydraulic motor 40a...port 40b...port 41...Oil road 42...Oil road 43...Check valve 44...Pressure compensation valve for meter out 45...Pilot control valve 47...Pressure compensation valve for meter-in 48...Check valve 49...Pressure compensation valve for meter out AS...Anti-saturation signal pressure

Claims (2)

[Scope of utility model registration request] 1. A control valve that selectively controls the direction and flow rate of supplying hydraulic pressure from a hydraulic supply line connected to a hydraulic pressure supply source to a pair of ports of a reciprocating actuator using an external pilot pressure, and this control valve. In a hydraulic control device equipped with a meter-in pressure compensation valve that is installed in the hydraulic supply line upstream of the valve and controls the flow rate so that the differential pressure between the inlet and outlet of the control valve becomes a set value, 1
The set value is the differential pressure between the inlet and outlet of the control valve and the check valve that allows hydraulic pressure to flow to the oil passage connecting at least the port on which load pressure acts among the paired ports to the control valve. A hydraulic control device characterized in that a meter-out pressure compensation valve is provided in parallel to control the flow rate. 2. A plurality of sets of control valves, meter-in pressure compensation valves, and meter-out pressure compensation valves respectively corresponding to the plurality of reciprocating hydraulic actuators are provided, and the plurality of meter-in pressure compensation valves and the plurality of meter-out pressure compensation valves are provided. Claim 1, wherein the pressure compensation valve is configured to receive an anti-saturation signal pressure supplied from the outside to reduce each of the differential pressures when limiting the meter-in flow rate to each hydraulic actuator. Hydraulic control device described in.