JPS5943202A - Hydraulic control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention supplies the necessary flow rate and pressure to the actuator when the actuator is in operation, and when the actuator is in neutral and is not in operation, the discharge rate of the variable pump is reduced.
This invention relates to a hydraulic control circuit that reduces 1.

As this type of circuit, a negative control circuit and a load sensing control circuit are conventionally known.

However, the conventional negative control circuit described above has the disadvantage that it cannot control the actuation of the actuator, and therefore cannot achieve the full energy saving effect.

Furthermore, the load sensing control circuit described above can achieve an energy saving effect during the operation of the actuator, but -1-
Since the circuit pressure is almost zero when the actuator is not operating and is in the neutral state, there is a drawback that it takes time to increase the circuit pressure to the required pressure when the actuator starts operating.

This invention provides the f1 movement of the actuator 'I+! , to,
Hydraulic control that supplies the required flow rate and pressure to the actuator, maintains the circuit pressure at a certain constant pressure when the actuator is neutral, and shortens the period of time when the actuator starts operating. The purpose is to provide circuits.

Embodiments of the present invention will be described below based on the drawings.

In the first embodiment shown in FIG. 1, a flow rate adjustment switching valve 2 is installed on the downstream side of the 11-tube conversion pump 1. 4. A load detection boat 5 forms an "f boat 6" therein.

The above-mentioned inflow valve ]・3 communicates with the 1-Kimachi Hen Bomb 1 via the load check valve 7 and the main passage 8, and ′-16 when the Meteor Adjustment Switching Valve 2 is in the neutral position shown. While this inflow boat is blocked, by switching the switch r2 to either the left or right side, the inflow port 3 is communicated with either the actuator channel 10 or 11 which communicates with the actuator 9. .

-1- The tank bow I/4 directly communicates with the tank 12, while the actuator flow path 10 or 11 of 1- is communicated with the tank 12 depending on the switching position of the flow adjustment switch jC2.

1-The load detection boat 5 described above communicates with the tank boat 4 when the flow adjustment J switching valve 2 is in the middle S'/ position shown in the figure, and when the switching valve 2 is switched to either the left or right side. , communicates with the flow path on the pressure oil supply side of the actuator flow paths 10.11, and transmits the load pressure of the flow path on the pressure oil supply side to the shuttle valve j+4 via the first pilot passage 13. The structure is designed to guide you.

Further, the neutral boat 6 communicates with the variable pump 1 via a branch passage 15, and the neutral port 6 is closed when the switching valve 2 is switched to either the left or right side.

By switching the meteor adjustment switching valve 2 to either the left or right position, the inflow boat 3 communicates with either the actuator channel IO or 11 as described above. Depending on the amount, the inflow boat 3
The relationship is such that the aperture area, that is, the aperture area is determined.

Furthermore, a first throttle 1 is provided on the downstream side of the flow rate adjustment switching valve 2.
7 and a second throttle 18 are provided, and the downstream side of the second throttle 18 is connected to a tank 19.

Furthermore, a low pressure relief valve 20 is connected to the upstream side of the first throttle 17.

On the other hand, an output detection passage 21 for detecting the output of the pump 1 is connected to the main passage 8 between the variable pump 1 and the flow rate adjustment switching valve 2.
is communicated with the tilt angle control device 22.

The tilting angle control device 22 includes a differential pressure sensing control valve 23 and a safety jt24.

The differential pressure sensing control valve 23 guides the pilot pressure of the distribution force detection passage 21 to one pilot chamber 25, and the other pilot chamber 26 is provided with a spring 27, and the main pilot passage is It is connected to the shuttle valve 14 via the valve.

The shuttle valve 14 communicates with the first pilot passage 13 as described above, and is also connected to the second pilot passage 28, which is connected to the first throttle 17 and the second pilot passage 28. The intermediate pressure between the throttle 18 and the throttle 18 is introduced into the shuttle valve 14.

Therefore, the spring force of the spring 27 and the higher pilot pressure of the first pilot passage 13 or the second pilot passage 29 come to act on the other Byron h chamber 26.

When the differential pressure sensing control valve 23 is in the right position as shown in the figure, the differential pressure sensing control valve 23 is connected to the tilting angle control cylinder 3 of the variable pump 1.
0 is communicated with the tank 31 to increase the discharge amount of the variable pump 1.

Furthermore, when the differential pressure sensing control valve 23 is switched to the left position in the drawing,
Pressure oil from the output detection passage 21 is supplied to the tilt angle control cylinder 30 to reduce the discharge amount of the variable pump l.

Note that 1- all the valves 24 are switched regardless of the operation of the differential pressure sensing control valve 23 when the pressure in the output detection passage 21 exceeds the set pressure, and the pressure oil in the output detection passage 21 is switched. is supplied to the tilting angle control cylinder 30, and the variable pump
This reduces the amount of discharge.

When the flow rate adjustment switching valve 2 is switched to one of the left and right positions, for example, to the left side position in the figure, the medium I and the boat 6 are blocked, and the pressure oil from the variable pump 1 is passed through the actuator flow path 10. Although it flows into the actuator 9, its throttle area is determined according to the switching point of the switching valve 2,
The differential pressure corresponding to the throttle surface JJIi is the flow rate adjustment switching valve 2.
Occurs before and after.

Note that the return oil from the actuator 9 returns to the tank 12 through the tank boat 4.

-1- When pressure oil flows into the actuator 9 and load pressure is generated as described in -1-, the load pressure is transmitted from the load detection boat 5 via the first pilot passage 13 and the shaft valve 14. , the other force of the differential pressure sensing control valve 23 flows into the pilot chamber 26 .

At this time, the pilot chamber 25 of the differential pressure sensing control valve 23
Since the pressure oil from the variable pump l flows in through the output detection passage 21, the differential pressure sensing control f? 23, depending on the switching amount of the flow i adjustment switching block r2) 1! The pressures before and after the throttle are opposed to each other. In other words, the discharge pressure of the variable pump and the load pressure of the actuator are opposed to each other as described above.

Therefore, a differential pressure is generated before and after the throttle area determined according to the switching height of the flow rate adjustment switching valve 2C.
Since it is always equal to the spring force of 7, the differential pressure is always -
・Kept constant.

In other words, the differential pressure sensing control (
j23 performs its control function.

To explain in more detail, the differential pressure sensing side 1 JII valve 23
When the discharge pressure of the variable pump 1 is higher than the sum of the load pressure of the other pilot chamber 26 and the spring force of the spring 27, the differential pressure sensing control valve 23 is switched to the left position in the figure, and the is supplied to the tilting angle control cylinder 30 to reduce the discharge amount of the pump l.

On the other hand, when the total value of the other pilot chamber 26 and the spring 27 is higher than the discharge pressure of the pump I, the differential pressure sensing control valve 23 is switched to the right position as shown in the figure.
The cylinder 30 is communicated with the tank 31 to increase the discharge amount of the variable pump 1.

As described above, the discharge amount of the variable pump 1 is adjusted so that the differential pressure before and after the meteor adjustment switching valve 2 is always kept constant, and the pressure and flow rate required by the actuator 9 are always supplied. Become.

This is because even if the load on the actuator 9 increases or decreases, the differential pressure generated before and after the flow rate adjustment switching valve 2 is always kept constant.

Next, when the flow rate adjustment switching valve 2 is returned to the neutral position 1η shown in the figure, the inflow boat 3 is closed and the pilot passage 13 is closed.
is in communication with the tank 12, and the neutral boat 6 is opened to allow oil from the variable pump 1 to flow out into the channel 1B.

Therefore, the discharge oil of the variable pump 1 is the first throttle 17.
Since the water flows to the tank 19 via the second throttle 18, pressure is generated between the first throttle 17 and the second throttle 18.

This pressure changes from the second pilot passage 28 to the shuttle valve 14.
It flows into the other pilot chamber 26 of the differential pressure sensing control valve 23 via the pass main pilot passage 28 . In other words, the rear pressure of the first throttle 17 flows into the second pilot chamber 26, and the front pressure flows into one of the pilot chambers 25.

In this state fm, the differential pressure sensing control 'jt23 is -
Since the control function is performed in the same manner as described above, the discharge pressure of the variable pump 1 is maintained at a pressure equal to the differential pressure corresponding to the spring force of the spring 27.

Therefore, when the flow rate adjustment switching valve 2 is held at the neutral position, the circuit pressure does not become extremely low, and is maintained at a pressure M1 equal to the above-mentioned differential pressure.

When the flow rate adjustment switching valve 2 is switched to the neutral position from the state in which the 7 actuator 9 is operated as described above, the circuit pressure is maintained at the set pressure of the low pressure relief valve 2o, that is, the low pressure. Therefore, even if the flow rate adjustment v1 switching valve 2 is suddenly switched to the neutral position, no peak pressure is generated.

The second embodiment shown in FIG. 2 has a plurality of flow rate adjustment switching valves and accordingly a plurality of actuators.

That is, on the downstream side of the flow rate adjustment switching valve 2, another flow rate adjustment switching valve r32 having the same configuration is provided, and an actuator 33 is attached to this flow rate adjustment switching valve 32.

Furthermore, a pressure control valve 34.35 is provided on the 1-stream side of each of the flow rate adjustment switching valves 2.32.

The pressure control valve 34 provided on the upstream side of the flow rate adjustment switching valve 2 is connected to the main passage 8 and guides oil from the main passage 8 to the inflow boat 3.

The pressure i'17 control valve 34 thus configured is operated from its origin side, that is, from its downstream side, via the pilot flow path 36.
The pilot I pressure is introduced into one pilot chamber 37 of the pressure control valve 34.

In addition, the other pilot chamber 38 is provided on the opposite side from the one pilot chamber 37, and this pilot chamber 38 is equipped with a spring 39, and the biro I/pressure of the first pilot passage 13 is The load pressure of the actuator 9 is guided.

Further, the pressure control valve 35 on the downstream side is connected to the parallel passage 4
0 to the main passage 8, and the /JE motor control valve 35 via this parallel passage 4o.
The structure is such that the oil from the +q variable pump 1 that flows into the tank is guided to the inflow boat 41 of the meteor adjustment switching valve 32.

The pressure control valve 35 configured in this way is connected to the pilot flow path 42.
A spring 45 is provided in the other pilot chamber 44, and the load pressure from the load detection boat 46 is guided to the third pilot chamber 43 through the outlet side.
This other pilot chamber 4 via the pilot passage 47
4, and its configuration is that of the pressure control valve 3 on the upstream side.
It is exactly the same as 4.

In this second embodiment, f32 pi iff ,, l- derived from between the first diaphragm 17 and the second diaphragm 18
The passage 29 and the third pilot passage 47 connected to the load detection boat 46 are connected via a shuttle valve 48, and the shuttle valve 48 and the shuttle valve 1
4 through a passage 49.

Therefore, the higher pressure in the second pilot passage 29 and the third pilot passage 47 is selected and flows into the passage 49, and the higher pressure in the passage 49 and the first pilot passage 13 is selected. Selected main pilot passage 28
There will be an influx into

Note that the flow rate adjustment switching valve 32 is formed with a tank boat 50 and a neutral boat 51 similarly to the flow rate adjustment switching valve 2, and when the flow rate adjustment switching valve p32 is in the neutral position shown, the load detection port 4G is connected to the load detection port 4G. is connected to the tank 52.

However, IIF in the above, Il! : When the adjustment switches JR 2 and 32 are held at the neutral position indicated by 1Δ, the variable pump 1 is connected from the main passage 8 to the neutral port 6 of the upstream flow rate adjustment switching valve 2 to the neutral flow path 16. → Neutral boat 51 with downstream flow rate adjustment switch 32 → Neutral flow path 53 → First
[Aperture] 7→Returns to the tank 19 via the second aperture 18.

In the neutral position shown in "-", the double-flow control switching valve 2.3
Since the second load detection boat 3.46 communicates with the tank 12.52, the first pilot passage 13 and the third pilot passage 47 become tank pressure, and the pilot pressure in the second pilot passage 29 becomes It flows into the tilting angle control device 22 via the main passage 2, and is controlled in the same way as in the first embodiment of NIJ. That is, the pressure of the circuit 1L is maintained at a certain constant level without being extremely low.

Further, if both flow rate adjustment switching valves 2 and 32 are switched at the same time, these pressure control valves 34 and 35 function as follows.

First, to explain the case where the flow rate adjustment switching valve 2 is switched to the left position, the discharged oil that has passed through the pressure control brake r34 is
The inflow boat 3 flows into the actuator 9 through one actuator flow path lO. The return oil from the actuator 9 is returned to the tank 12 from the other actuator flow path 11 via the tank boat 4.

At this time, the oil that has passed through the pressure control valve 34 flows into one pilot chamber 37 of the pressure control valve 34 via the pilot flow path 36.

Further, the load pressure of the actuator 9 flows from the load detection boat 5 into the other pilot chamber 38 of the pressure control valve 34 .

Therefore, the pressure before power distribution and the pressure on the supply side of the variable pump 1 are opposed to each other via the pressure control valve 34, but in exactly the same way as in the case of the differential pressure sensing control valve 23 described above, The differential pressure after the flow rate adjustment switching jr 2 +ii+ is always maintained to correspond to the spring force of the spring 39, and the actuator 9 is supplied with the pressure and flow rate at the center.

In other words, when the pressure on the output 1 side of the pressure control valve 34 is higher than the load pressure, the pressure control valve 34 moves against the spring 39, and -1- f1. 1'rl'+i Reduce M.

Further, when the pressure on the outlet side is lower than the load pressure, the pressure control valve 34 moves in the opposite direction to the above, thereby increasing the opening area on the outlet side.

In this way, the pressure control valve 34 allows only the flow rate required by the cutter 9 to be supplied to the cutter 9.
The surplus flow ridge flows into the pressure control valve 35 on the downstream side via the rose 1/le passage 40.

This pressure control valve 35 also functions in exactly the same way as the pressure control valve 34 on the upstream side, and supplies the actuator 33 with the necessary pressure and flow rate.

Since the one-way control valves 34 and 35 function as described in -I-, even if the load pressure of either actuator 9 or 33 is low, oil from the variable pump l is only applied to the lower actuator. is never supplied. .

As is clear from the above description, this invention has the following features.

A variable pump having a tilting angle control cylinder and a load detection boat that adjusts the throttle opening on the supply side according to the switching amount and detects the load pressure of the actuator,
and a flow rate adjustment switching valve that blocks the inflow boat that serves as a supply flow path to the actuator in the neutral position, and a flow rate adjustment switching valve provided downstream of the meteor adjustment switching valve, and furthermore, the meteor adjustment switching valve is held at the neutral position. a first throttle communicating with the variable pump via a neutral flow path; a second throttle provided further downstream of the first throttle; 1. A low pressure relief valve connected to the upstream side of the first throttle, a pilot passage led from the -1 and 4 load detection ports, and a pilot passage led from the line connecting the first and second throttles -1. , a shuttle valve that merges both pilot passages and selects the higher pilot pressure, a main pilot passage that leads the pilot pressure from this shuttle valve, and one pilot chamber connected to the discharge side of the variable pump. Then, the other pilot chamber is connected to the main pilot passage, and the pressure difference between the two is sensed to control the tilt angle control cylinder, so that the pressure difference before and after the flow if adjustment switching valve is always -. The present invention is characterized in that it is equipped with a tilting angle control device equipped with a differential pressure sensing control valve that controls the discharge amount of the +1'l' variable pump so as to maintain the same value.

With the above configuration, the differential pressure before and after the throttle, whose opening degree is determined according to the switching amount of the flow rate adjustment switching valve, is sensed by the differential pressure sensing control valve, and the pressure can be varied by 14''-1. The discharge amount of the pump is controlled to keep the differential pressure constant even if the load on the nuclear actuator changes.

Therefore, while the actuator is in operation, the necessary pressure and meteor are supplied to the actuator, thereby saving energy.

Furthermore, when the meteor adjustment switching valve is held in the neutral position, the differential pressure sensing control valve senses the pressure between the first and second throttles and adjusts the discharge amount of the nf variable pump, so the circuit pressure does not become extremely low.

In this way, since the circuit pressure at the neutral state can be maintained to a certain extent at 1 m11, the rise time of the actuator at startup becomes faster.

In addition, the circuit pressure when the flow rate adjustment switching valve is returned to the neutral position is maintained at low pressure by the low pressure relief valve.
Even if the flow rate adjustment switching valve mentioned above is suddenly switched to the neutral position, peak pressure will occur in the circuit.

do not have.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, and FIG. 2 is a circuit diagram showing a second embodiment. 1.φ variable pump,? , 32...Dispute+J adjustment switching valve, 3.41-...Inflow port, 5.4G...-Load detection boat, 8...Main passage, 9.33...Actuator, 13.29 and 47-・・Ba・f lot aisle, 1
411・War shuttle valve, 16.53・・Neutral flow path, 1
7... First throttle, 18... Second throttle, 20... Low pressure relief valve, 22... Tilt angle control device, 23...
Differential pressure sensing control valve, 25.26 - Pilot room, 2nd... Main pilot passage, 30... Cylinder for tilting angle control. Representative Patent Attorney Yoshinohi Shima 1 Figure

Claims (1)

[Claims] A variable pump having a cylinder for controlling a tilting angle, and a load detection port that adjusts the throttle opening on the supply side according to the switching amount and detects the load pressure of the actuator. , and actuate in neutral position. A flow rate adjustment switching valve is installed downstream of the flow regulating switch valve, which blocks the inflow boat that serves as the supply flow path for the evening, and when the flow regulating switching valve is held at the neutral position, the neutral A first throttle communicating with the variable pump described in - through a flow path, and a second throttle provided further downstream of the first throttle.
- a low pressure relief valve connected to the flow side of the first throttle; (- a pilot passage led from the charge distribution detection port; - a line connecting the first throttle and the second throttle). a shuttle valve that merges both pilot passages and selects the pilot pressure with higher pressure, a main pilot passage that leads pilot pressure from this shuttle valve, and a pilot chamber for force. The cylinder is connected to the discharge side of the bomb, and the other pilot chamber is connected to the above-mentioned main pylon) and passage, and the differential pressure between the two is sensed to control the above-mentioned tilting angle control cylinder fJj and adjust JAj-1ij. Ensure that the differential pressure before and after the switching valve is always constant >! /11ik A hydraulic control circuit consisting of a tilting angle control device equipped with a differential pressure sensing control block V for controlling the discharge point of a variable pump.