JPH03157502A - Hydraulic circuit having flow rate controlling function - Google Patents

Abstract

PURPOSE:To facilitate operation by providing a computing means which computes discharge rate of a hydraulic pump and a computing means which computes the grand total of flow rate required by a load, a computing means which performs comparison, and a computing means which multiplies a command value of an operational part by a coefficient between the operational part of a solenoid operational type directional changeover valve and an operation device. CONSTITUTION:Directional changeover valves 5a to 7a arranged between a hydraulic pump 1 and actuators 20 to 22 are solenoid operational type, and operational command signals of a control means 30 are applied to operational parts 5b, 5c to 7b, 7c. A signal of an operational device 31 output according to the operational rate of handle, rotational speed (n) of a driving engine 3 of the hydraulic pump 1, and an electric signal (p) of oil pressure of an operational part 1e are inputted to the control means 30. The control means 30 has a discharge rate computing means of the hydraulic pump 1, an operational rate computing means of grand total of flow rate required by load, a means which compares outputs of both computing means to each other, and a means which multiplies a command value of the operational part by a coefficient of proportional distribution from the thus obtained result. The operation is thus facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit having a flow rate control function used in construction machinery and the like.

(Prior Art) A conventional hydraulic circuit having a flow rate control function is shown in FIG. 4 (a hydraulic circuit diagram in which the hydraulic circuit disclosed in Japanese Patent Application Laid-open No. 188604/1983 is rewritten as a hydraulic circuit).

In FIG. 4, l is a hydraulic pump with a variable discharge chamber.

In this hydraulic pump 1, the tilt angle of the swash plate 2 is controlled by the output of the hydraulic cylinder 1f, and the discharge flow rate to the main circuit 4 changes depending on the tilt angle of the swash plate. The hydraulic cylinder if is.

The pilot circuit 14 has a pressure chamber 1b connected to the thorn IC, and if pressure oil does not act on the pressure chamber 1b, the rod ld
is held in the position shown by a spring lc. At this time, the discharge flow rate of the hydraulic pump 1 to the main circuit 4 is at its minimum.

The main circuit 4 on the discharge side of the hydraulic pump 1 includes directional control valves 5 to 5.
7 are connected in parallel. Each of these directional control valves 5 to 7
are connected to loads WO to W2 such as actuators via pressure compensation valves IO to 12.

The pressure compensation valve 10 includes a spring chamber 10 having a spring lOa.
b, and a pressure chamber 10c at a position opposite to the spring chamber 10b via the main valve 10d.
, the hydraulic pressure on the downstream side of the directional control valve 5 is connected to the pilot circuit 1.
3a, and the hydraulic pressure of the pilot circuit 14 acts on the spring chamber 10b. When the main valve 10d or the difference between the pressing force between the spring chamber 10b and the pressure chamber 10c increases, the pressure compensating valve 10 moves greatly to the left from the position shown in the figure, and the directional control valve 5 and the load WO Increase the number of connections.

Conversely, when the difference between the pressing forces between the spring chamber 10b and the pressure chamber 10c becomes smaller, the main valve 10d decreases the amount of movement toward the left from the illustrated position, thereby reducing the amount of connection of the load WO of the directional control valve 5. Make it smaller. (The pressure compensating valves 11 and 12 have the same structure as the pressure compensating valve 10, so the same parts of the pressure compensating valves 10 to 12 have numbers 11, 12 representing the respective pressure compensating valves.
are subscripted with the same alphabet, only the numbers are shown, and their explanations are omitted. ) The pilot circuit 14 connected to the hydraulic cylinder la of the hydraulic pump l and the spring chambers 10b to 12b of the pressure compensation valves 18 to 12 is connected to the output side of the high pressure selection circuit 15. This high voltage selection circuit 15 has a load W
A selection valve 16 that selects the high pressure side of the load circuit 21 connected to the load circuit 2z and the load circuit 2z connected to the load W2;
6 and a selection valve 17 which selects the high pressure side of the load circuit 2o connected to the load WO or the output side of the high pressure selection circuit 15, and the pilot circuit 14 It is connected to the output side of the selection valve 17. Therefore, the highest pressure of the load pressures in the load circuits 20 to 21 to the loads Wo to W2 acts on the pilot circuit 14.

The conventional hydraulic circuit having the flow control function having the above-mentioned configuration applies a load pressure corresponding to the highest load among the loads WO to W2 to the spring chambers 10b to 12b of the pressure compensation valves 10 to 12 through the pilot circuit 14. act through. Further, the hydraulic pressure of the pilot circuit 14 is applied to the pressure chamber 1b of the hydraulic cylinder 1a, and the discharge hydraulic pressure of the hydraulic pump 1 is controlled by the pilot circuit 1.
The discharge flow rate is controlled to be higher than the oil pressure of No. 4 by a certain amount.

In such a situation, when the directional switching valve 5 and the directional switching valve 6 are operated, the oil pressure on the upstream side of the pressure compensation valve IO and the pressure compensation valve 11 increases according to their opening degrees, and the oil pressure is equal to the pilot pressure. Circuit 1: Ia acts on pressure chamber 10c and pressure chamber 11c via pilot circuit 1b. Then, the main valve 10d of the pressure compensation valve 10 connects the pressure chamber Inc and the spring chamber 1.
．． The main valve 11d of the pressure compensation valve 11 moves to the left depending on the pressure difference between the pressure chamber 10c and the spring chamber 10b. Therefore, the differential pressure before and after the throttle formed by the directional control valve 5 and the directional control valve 6 is maintained at a constant value of the pressing force of the spring 10a and the spring lla, and the amount of oil supplied to the load WO1 and the load W1 is controlled. , directional switching valve 5, directional switching valve 6
Set the value according to the amount of operation. Note that the same applies when all of the directional control valves 5 to 7 are operated, so a description thereof will be omitted.

(Problems to be Solved by the Invention) In the above conventional technology, the pressure compensating valves IO to I2 adjust the pressure on the downstream side of the directional control valves 5 to 7 to the highest hydraulic pressure among the loads wo to w2, and By determining the discharge flow rate of the pressure oil so that a higher oil pressure is generated in the pump l, the differential pressure before and after the directional control valves 5 to 7 is kept constant, and the operation amount of the directional control valves 5 to 7 is controlled. Pressure oil is distributed to the loads WO to W2 accordingly. This action is such that when the amount of oil required by the loads Wo to w2 exceeds the amount of oil discharged from the hydraulic pump l, the oil pressure in the pilot circuits 13a to 13b on the upstream side of the pressure compensation valves 10 to 12 is The main valve IQd~12 of the pressure compensation valve Io~12 decreases according to the amount of operation.
d is moved by spring loa~12a. Therefore, the operation of the pressure compensation valves 10 to I2 is limited to the springs 10a to 12.
Affected by a.

Due to the above reasons, the hydraulic circuit with this flow control function is
When the amount of oil required by the load WO~w2 is smaller than the amount of oil discharged from the hydraulic pump l, the oil pressure in the upstream pilot circuits 13a~13b of the pressure compensating valves 10~12 can be secured, so the distribution ratio is set to the directional control valves 5~ The value corresponds to the operation amount of 7. However, when the amount of oil required by the loads wo to W2 is larger than the amount of oil discharged from the hydraulic pump, the springs 10a to 12a of the pressure compensating valves 10 to 12 are
As the amount of deflection changes, the oil distribution ratio to the load changes. Therefore, the load W with respect to the operation command value of the directional valve
There is a problem that the operations of O to W2 do not correspond accurately.

(Means for Solving the Problems) The technical means of the present invention for solving the problems of the prior art is to provide a plurality of directional control valves connected to loads such as actuators on the discharge side of a variable discharge type hydraulic pump. A pressure compensation valve is provided on the upstream side of the directional switching valve, and has a spring chamber connected to the downstream side of the directional switching valve, and a pressure chamber opposing the spring chamber and connected to the upstream side of the directional switching valve, and each of the above-mentioned A selection circuit for selecting the highest value of load pressure is provided in the load circuit of the load connected to the directional switching valve, and the output side of this selection circuit is connected to the discharge flow rate control section of the hydraulic pump, and the discharge flow rate of this hydraulic pump is controlled. , a flow rate control configured to control the amount of oil required for the loads connected to the side directional switching valves, and distribute the amount of oil discharged from the hydraulic pump to each load by the pressure compensating valve and the directional switching valve. Alternatively, in a hydraulic circuit having a function, a plurality of directional switching valves connected to loads such as actuators are provided on the discharge side of a fixed discharge type hydraulic pump, and the downstream side of the directional switching valve is connected to the upstream side of the directional switching valve. a pressure compensation valve having a spring chamber and a pressure chamber opposing the spring chamber and connected to the upstream side of the directional control valve;
A selection circuit for selectively detecting the maximum value of the load pressure is provided in the load circuit to which the load connected to the directional control valve is connected, and the output of the selection circuit is provided between the main circuit on the discharge side of the hydraulic pump and the tank. A bleed-off type pressure control valve is provided which opposes the spring chamber to which the side is connected and which is connected to the main circuit via a main valve. Flow rate control '4i4 function configured to maintain a constant value higher than the load pressure of the directional switching valve and distribute the discharge hydraulic pressure of the hydraulic pump to each load by the directional switching valves and pressure compensation valves on the sides. In the hydraulic circuit, the directional control valve is an electromagnetically operated directional control valve, and the directional control valve is provided between an operating section of the electromagnetically operated directional control valve and an operating device for the electromagnetically operated directional control valve. discharge flow rate calculation means for calculating the discharge flow rate of the hydraulic pump; operation amount calculation means for calculating the sum of the flow rate required by the load from the sum of the operation amounts of the respective electromagnetically operated directional control valves; and the discharge flow rate calculation means. Comparison calculation means for comparing the output of the means and the output of the operation amount calculation means 3, and when the output of the operation amount calculation means is larger as a result of this comparison calculation, proportionate distribution is made to the command value of the operation unit. The present invention is characterized by providing a control means comprising a proportional distribution multiplication means for multiplying by a coefficient of .

[For production]

The present invention having the above-mentioned technical means is applicable when the directional control valve is operated in excess of the amount of oil discharged by the hydraulic pump, or when the amount of oil discharged by the hydraulic pump becomes insufficient due to load fluctuations during operation of the directional control valve. Since the operation command to the directional control valve is changed by the control means in proportion to the amount of operation of the directional control valve so as to match the amount of oil discharged from the hydraulic pump, the pressure compensation valve is not fluctuated. Therefore, even if it becomes necessary to supply oil to the loads WO to W2 in excess of the discharge flow rate of the hydraulic pump, the amount of oil supplied to the loads WO to W2 will be a value proportional to the original operation amount.

(Embodiment) The first embodiment of the present invention will be described below as shown in Fig. 1 (A) and Fig. 2 (A).
, will be explained with reference to FIG. In addition, for the explanation,
Only the points that are different from the conventional technology described above will be explained.

In FIG. 1(A), the hydraulic pump l has its operating section 1.
This is a variable discharge type hydraulic pump whose discharge flow rate changes depending on the hydraulic pressure of the pilot circuit 14 acting on the pump. The operating section 1e of the hydraulic pump 1 has a device that converts the hydraulic pressure into electricity, and the output signal of the device is inputted to the control means 30.

Pressure compensating valves 23 to 25 are connected to the discharge side of the hydraulic pump l, and each of the pressure compensating valves 23 to 25 has a
It is configured to connect to loads WO to W2 via directional switching valves 58 to 7a.

The pressure compensation valve 23 has a spring 23a and the directional control valve 5
a spring chamber 23b connected to the downstream side of the directional control valve 5a via a pilot circuit 18a;
A pressure chamber 23c is connected to the pressure chamber 23c via a. This pressure compensation valve 23 maintains the pressure on the upstream side of the throttle formed by the directional switching valve 5a as high as the pressing force of the spring 23a of the spring chamber 23b. Therefore, the amount of oil that passes through the directional switching valve 5a corresponds to the amount of operation of the directional switching valve 5a. Further, the main valve 23d of the pressure compensation valve 23 is normally in a fully open position,
The circuit is narrowed down by the oil pressure difference between the spring chamber 23b and the pressure chamber 23c. Note that the other pressure compensating valves 24 and 25 have the same configuration and function as the pressure compensating valve 23, so the same parts are given the same suffixes and detailed explanation thereof will be omitted. In addition, those corresponding to the pilot circuit 18a are 18b,
18c, pilot circuit 19a corresponds to 19b
, 19c. The directional control valves 5a to 7a are
Electromagnetic operation type directional switching valve, its operating parts 5b, 5c to 7
The operation direction and amount of operation are determined by operation command signals applied to signals b and 7c from the operation device 31 via the control means 3o.

Operation parts 5b, 5c to 7b, 7c of directional switching valves 5a to 7a
is connected to the operating device 31 via the control means 30,
The rotational speed n of the engine 3 that drives the hydraulic pump 1 and the oil pressure of the operating section 1e are converted into an electric signal P and inputted to the other side of the control means KO.

The operating device 31 is composed of a joystick or the like, and the voltage changes depending on the amount of operation thereof. That is, in FIG. 2(A), the joystick handle 3
1a is in the center position, the operating part 5b of the directional control valve 5a
, 5c are not issued, and when the handle 31a is operated in the direction of the arrow, the switch 32a is activated.
When the switch is switched to the contact side, an operation command corresponding to the operation amount of the handle 31a is applied to the operation section 5b. Similarly, when the handle 31a is operated in the direction of arrow C, the switch 32a is switched to the contact C side, and an operation command corresponding to the amount of operation of the handle 31a is applied to the operation section 5C. Moreover, the output signal of the operating device 31 is
The signal is applied to a multiplexer 33 of the control means 30.

The operation unit (e) of the hydraulic pump l and the output signal of the engine 3 are applied to a function circuit 34 that calculates the discharge flow rate Q of the hydraulic pump 1 from these two values, and the discharge flow rate Q of the hydraulic pump l is applied to a multiplexer 33. The analog signals applied to these multiplexers 33 are A-D.
The voltage is applied to the arithmetic unit 36 via the converter 35, and is applied to the operation unit 5 of the directional control valves 5a to 7a via the interface 37.
b, 5C to 7b, 7C.

As shown in FIG.
~31c is read, and from the value transmitted as a digital signal via the A-D converter 35, the amount of oil QO~Q2 that each directional control valve attempts to pass is calculated, and the value is A manipulated variable calculating means 40 that calculates the total load oil amount Qv required by the load WO-W2 from the added value.
and a discharge flow rate calculating means 41 which calculates the discharge oil amount Qp of the hydraulic pump l from the output of the function circuit 34 applied to the multiplexer 33 and transmitted as a digital signal via the A-D converter 35; Discharge oil amount Q of hydraulic pump 1
The load oil amount Qv required by the loads WO to W2 is subtracted from p, and if the value Qc (oil amount Qp - oil amount Qv = Qc) is negative (value Qc<O), the operation amount calculation means 43 is activated. command,
If the value Qc is positive (value Qc≧0), the manipulated variable calculation means 4
4, and a comparison calculation means 42 for issuing commands for the operations of 4.

Note that when the output of the comparison calculation means 42 becomes a negative value, the operation amount calculation means 43 calculates a flow rate Ql~ required by each load calculated from the operation command signals Sl~S3 to the operation command signals Sl~S3. The operation command signals Sl' to S2' obtained by correcting the product of Q3 and Qp/Qv are applied to the operating parts 5b, 5c to 7b, and 7c of the directional control valves 5a to 7a,
When the output of the comparison calculation means 42 becomes 0 or a positive value, the operation amount calculation means 44 outputs the operation command signal Sl~
The current value of the signal S3 is applied to the operation parts 5b, 5c to 7b, and 7c of the directional control valves 5a to 7a.

The operation of the first embodiment having the above configuration will be explained.

In FIG. 1(A), when the hydraulic pump l is driven by the engine 3 and pressure oil is discharged into the main circuit 4, the directional switching valve 5a and the directional switching valve 6a are operated by a command from the operating device 31. Then, the discharge pressure oil of the hydraulic pump l flows from the main circuit 4 to the load WO via the pressure compensation valve 23 of the load circuit 20 and the directional switching valve 5a, and also flows into the load WO through the pressure compensation valve 24 of the load circuit 21. It flows into the load W1 via the directional switching valve 6a.

At this time, the load WO and Wl are smaller than the load WO.
If l is lighter, its load pressure is reduced by the selection valve 16 and selection valve 17 of the high pressure selection circuit 15.
The load pressure acts on the pilot circuit 14 via the selection valve 17, and the oil pressure acts on the operating part 1e of the hydraulic pump l,
The hydraulic pump 1 controls the discharge pressure of the operating part 1e to a value higher than the load pressure of the load WO by a certain value.

In this way, the oil pressure of the main circuit 4 is controlled to a value higher than the load pressure of the load WO by a certain value, and the oil pressure of the main circuit 4 is controlled to be higher than the load pressure of the load WO.
0 pressure compensation valve 23. It acts on the pressure compensation valve 24 of the load circuit 21. This pressure compensating valve 23 has its pressure chamber 23c.
Since the hydraulic pressure on the upstream side of the directional control valve 5a is acting on the spring chamber 23b, and the hydraulic pressure on the downstream side of the directional control valve 5a is acting on the spring chamber 23b, the main valve 2''ld is connected to the directional control valve 5a. The pressure difference before and after is maintained at a value corresponding to the pressing force of the spring 23a of the spring chamber 23b.

Similarly, the pressure compensation valve 24 has its pressure chamber 24c acted on by the hydraulic pressure on the upstream side of the directional control valve 6a, and its spring chamber 24c.
Since the hydraulic pressure on the downstream side of the directional switching valve 6a is acting on the directional switching valve 6a, the main valve 24d maintains the pressure difference before and after the directional switching valve 6a at a value corresponding to the pressing force of the spring 24a in the spring chamber 24b. do. Therefore, the flow rate of pressure oil supplied to the load WO is:
The value corresponds to the amount of operation of the directional switching valve 5a, and similarly, the flow rate of the pressure oil supplied to the load Wl has a value depending on the amount of operation of the directional switching valve 6a.

In the operation of the above hydraulic circuit, the control means 30 functions as follows. For example, directional switching valve 5a, directional switching valve 6a
handle 31a and handle 31b of the operating device 31 that transmits the differential command.
The command value is applied to the multiplexer 33, which converts the pilot oil pressure of the pilot circuit 14 acting on the operating part 1e into electricity and applies it to the function circuit 34 as the oil pressure signal p, and also converts the rotation speed of the engine 3 into an electric signal. It is converted into a rotation speed signal n and applied to the function circuit 34. Function circuit 3
4 calculates the discharge oil amount Q of the hydraulic pump l from these two signals, and applies it to the multiplexer 33 as the discharge oil amount Q of the hydraulic pump l. Each of these signals is sent to multiplexer 3
3, and the detected analog signals are applied as digital signals to an arithmetic unit 36 via an A-D converter 35. The calculation device 36 receives an operation signal S1 of the joystick handle 31a of the operation device 31,
When the operation signal S2 of the joystick handle llb is sequentially detected by the multiplexer 33, the operation amount calculating means 40 determines whether the direction switching valve 5a and the direction switching valve 6a will supply the load WO1Wl based on the operation signals S1 and S2. Calculate the load oil amount Qv. Furthermore, when the discharge oil amount signal Q is applied by the multiplexer 33, the discharge flow rate calculation means 41 calculates the discharge oil amount Qp based on this discharge oil pressure signal Q. This discharge oil amount Qp and load oil amount Q
v means that the load oil amount Qv is subtracted from the discharge oil amount Qp by the comparison calculation means 42, and if the value is (Qp-Qv≧0) 0 or more, the load WO, Wl or the required oil amount is Since the amount of oil discharged from the pump l is greater than the amount of oil discharged from the pump l, the operation amount calculating means 44 operates the directional control valve 5a from the operating device l.
Operation signal S1 to directional control valve 6a. A signal equivalent to S2 is sent to the operation part 5b or 5c of the directional control valve 5a and the directional control valve 6.
The voltage is applied to the operating section 6b or 6C of a. In this way, when the operation command is applied to the directional switching valve 5a and the directional switching valve 6a,
As described above, the pressure compensation valve 23 and the pressure compensation valve 24 control the differential pressure between the directional switching valve 5a and the directional switching valve 5a, and control the load WO1 and the load wi.
Maintain the value according to the manipulated variable of a.

In the above operation, as a result of operating the operating device 31 and increasing the operating signal Sl, the load oil amount Qv calculated by the operating amount calculating means 40 increases, and the calculation result of the comparison calculating means 42 becomes (Qp-Qv< O) When it becomes smaller than O, the calculator 43a of the operation amount calculation means 43 multiplies the load oil amount Ql corresponding to the operation signal Sl by the value of the discharge oil amount Qp/load oil amount Qv, and the operation signal St' is smaller than the operation signal S1. as directional valve 5
The voltage is applied to the operation section 5b of a. Similarly, the calculator 43b multiplies the load oil amount Q2 corresponding to the operation signal S2 by the value of the discharge oil amount Qp/load oil amount Qv, and outputs the result as an operation signal S2' smaller than the operation signal S2. to be applied. Therefore, the load WO is reduced in proportion to the amount of operation of the operating device 31 or the operation of the directional switching valve 5a and the directional switching valve 6a until it becomes equal to the amount of oil discharged from the hydraulic pump l.
The speed of Wl decreases or decreases at the same rate, and the amount of operation of the operating device 31, that is, the joystick handle 31
The operation continues at a speed proportional to the amount of operation of a and 31b. In addition, the joystick handle 31a,
Even when all of 31b, :llc are operated, the operation continues at the same speed ratio according to the operation amount.

Next, a second embodiment will be described with reference to FIG. 1(B), FIG. 2(B), and FIG. 3.

The difference between the second embodiment shown in FIG. 1(B) and the first embodiment is that the hydraulic pump 1 is changed from a variable discharge type to a fixed discharge type, and between the main circuit 4 of the hydraulic pump 1a and the tank. In this configuration, a bleed-off type pressure compensation valve 8 is provided.

The bleed-off type pressure compensation valve 8 has the same structure as the pressure compensation valve 23 described above, and has a spring chamber 8 having a spring 8a.
b, and a pressure chamber 8c arranged in the spring chamber 8b via a main valve 8d.The spring chamber 8b is connected to the pilot circuit 14, and the pressure chamber 8c is connected to the pilot circuit 8c.
The configuration is such that it is connected to the main circuit 4 via. Note that the relief valve 8f limits the maximum pressure of the pilot circuit 8e.

The bleed-off pressure compensation valve 8 having such a configuration maintains the hydraulic pressure of the pilot circuit 14 acting on the spring chamber 8b higher by the pressing force of the spring 8a. In other words, the oil pressure of the main circuit 4 is maintained at a value higher than the load pressure of the loads WO to W2 by the pressing force of the spring 8a. The oil pressure of the main circuit 4 maintained at such oil pressure is controlled by the pressure compensating valves 23 to 25 according to the loads WO to W2 connected to each of the directional control valves 58 to 7a, and the directional control valves 5a-7a
Hydraulic pressure corresponding to the operation amount is supplied to the loads WO to W2.

The signal oil pressure input to the control means 30 is the oil pressure of the pilot circuit 14 converted into an oil pressure signal p by the oil pressure-electrical converter 9 and applied to the function circuit 34a of FIG. 2(B). It is converted into a discharge oil amount signal Q of 1a. Since the hydraulic pump 1a is of a fixed discharge type, this function circuit 34a is a function circuit that matches the characteristics of the hydraulic pump 1a.

The operations of the multiplexer 33, A-D converter 35, and arithmetic unit 36 of this control means 30 are similar to those of the first embodiment described above. That is, the operation amount calculation means 40 calculates the required load oil amount Qv from the operation amount of the directional control valves 58 to 7a, and the discharge flow amount calculation means 41 calculates the required load oil amount Qv from the operation amount of the directional control valves 58 to 7a.
The comparison calculation means 42 subtracts the load oil amount Qv from the discharged oil amount Qp, and the value Qc is O-
If it is smaller, the manipulated variable calculating means 43 multiplies each of the manipulated variables Sl to s3 by oil output amount Qp/load oil amount Qv to obtain corrected manipulated variable signals Sl' to S3', and then the directional control valve 5a The amount of restriction formed by ~7a is determined by each direction switching valve 58.
The load oil amount Qv passing through 7a is corrected to match the discharge oil amount Qp of the hydraulic pump 1a. Therefore, the pressure oil discharged from the hydraulic pump Ia is proportionally distributed to the loads WO to W2 without the pressure compensation valves 23 to 25 operating, so the load W
The ratio of change in the operating speed of the loads WO to W2 remains the same when the amount of oil requested by O to W2 exceeds the amount of oil discharged from the hydraulic pump 1a and when it does not.

(Effects of the Invention) As explained above, the present invention detects the total amount of pressure oil required by the load from the operation amount of the directional control valve, and calculates the discharge of the hydraulic pump from the hydraulic pump control oil pressure and the engine rotation speed. When the amount of oil is compared and calculated and the total amount of pressure oil required by the load is larger than the amount of oil discharged by the hydraulic pump based on the amount of operation of the directional control valve, the operation signal to each directional control valve is sent according to the amount of operation. Since the total amount of pressure oil required by the load is controlled from the operation amount of the directional switching valve so as to match the amount of oil discharged from the hydraulic pump, each pressure compensation valve operates normally. Therefore, when the amount of oil required by the load exceeds the amount of oil discharged by the hydraulic pump, the operating speed of the load decreases, or is the ratio reduced when the amount of oil required by the load does not exceed the amount of oil discharged by the hydraulic pump? It is similar to the operating ratio of . Therefore, when the total amount of pressure oil required by the load is larger than the amount of oil discharged by the hydraulic pump from the amount of operation of the directional valves, the operator can adjust the hydraulic pressure without changing the amount of operation of each directional valve. Since the operation can be performed with the same feeling as when the total amount of pressure oil required by the load is smaller from the amount of operation of the directional control valve than the amount of oil discharged from the pump, the operation becomes easier.

[Brief explanation of the drawing]

FIG. 1(A) is a hydraulic circuit diagram including an electrical system according to a first embodiment of the present invention, and FIG. 1(B) is a hydraulic circuit diagram including an electrical system according to a second embodiment of the present invention. Figure (A) is a control system diagram of the control means of the first embodiment. Figure 2 (B) is a control system diagram of the control means of the second embodiment. )
Block diagram showing the flow of functions of the arithmetic unit, No. 4
The figure is a hydraulic circuit diagram of a conventional technology. l...Variable discharge type hydraulic pump 1a...Fixed discharge type hydraulic pump 3...Engine 4...Main circuits 5a, 6a, 7a...Direction switching valve 8... Bleed-off type pressure compensation valve 9...Hydraulic-electrical converter 10-12...Pressure compensation valve 14...Pilot circuit 15...High pressure selection circuit 16.17... - Selection valves 20 to 22... Load circuits 3 to 25... Pressure compensation valve 0... Control means l... Operating device 2... Switch 3... Multiplexer 4. ... Function circuit 5 ... A-D converter 6 ... Arithmetic device 0 ... Manipulated amount calculation means l ... Discharge amount calculation means 2 ... Comparison means 3.44 ...Operation amount calculation means 3a, 43a, 43a...Arithmetic unit

Claims (2)

[Claims] (1) A plurality of directional switching valves connected to loads such as actuators are provided on the discharge side of a variable discharge type hydraulic pump, and a spring chamber and a spring chamber to which the downstream side of the directional switching valve is connected are provided on the upstream side of the directional switching valve. A pressure compensation valve having a pressure chamber facing the chamber and connected to the upstream side of the directional control valve is provided, and a selection circuit for selecting the highest value of the load pressure is provided in a load circuit of a load connected to each of the directional control valves. , the output side of this selection circuit is connected to the discharge flow rate control section of the hydraulic pump, and the discharge flow rate of this hydraulic pump is controlled to the required amount of oil for the load connected to each of the directional control valves, In a hydraulic circuit having a flow control function configured to distribute the amount of discharged oil to each load using the pressure compensating valve and the directional switching valve, the directional switching valve is an electromagnetically operated directional switching valve, and the directional switching valve is an electromagnetically operated directional switching valve. A discharge flow rate calculation means for calculating the discharge flow rate of the hydraulic pump is disposed between the operating section of the directional switching valve of the type and the operating device for the electromagnetically operated directional switching valve; A manipulated variable calculation means for calculating the total flow rate required by the load from the sum of the valve operation amounts, a comparison calculation means for comparing the output of the discharge flow rate calculation means with the output of the manipulated variable calculation means, and A flow rate characterized in that a control means is provided, comprising a proportional distribution multiplier that multiplies the command value of the operating section by a proportional distribution coefficient when the output of the resultant manipulated variable calculation means becomes larger. Hydraulic circuit with control function. (2) A plurality of directional switching valves connected to loads such as actuators are provided on the discharge side of a fixed discharge type hydraulic pump, and a spring chamber and a spring chamber to which the downstream side of the directional switching valve is connected are installed on the upstream side of the directional switching valve. A pressure compensation valve having a pressure chamber facing the chamber and connected to the upstream side of the directional switching valve is provided, and a maximum value of the load pressure of the load connected to the directional switching valve is selectively detected in a load circuit connected to the directional switching valve. A selection circuit is provided between the main circuit on the discharge side of the hydraulic pump and the tank, a spring chamber to which the output side of the selection circuit is connected, and a bleed chamber opposed to the spring chamber via a main valve and connected to the main circuit. An off-type pressure control valve is provided, and this bleed-off type pressure compensating valve maintains the discharge oil pressure of the hydraulic pump by a certain value higher than the load pressure of the directional control valve, and the discharge oil amount of the hydraulic pump is adjusted to the above-mentioned level. In a hydraulic circuit having a flow rate control function configured to distribute to each load with an individual directional switching valve and a pressure compensation valve, the directional switching valve is an electromagnetically operated directional switching valve, and the directional switching valve of the electromagnetically operated type is Discharge flow rate calculation means for calculating the discharge flow rate of the hydraulic pump, and a discharge flow rate calculation means for calculating the discharge flow rate of the hydraulic pump, and a control unit for each of the electromagnetically operated directional control valves, between the operating section of the switching valve and the operating device for the electromagnetically operated directional control valve. a manipulated variable calculating means for calculating the total flow rate required by the load from the sum total of the flow rate, a comparison calculating means for comparing the output of the discharge flow rate calculating means with the output of the manipulated variable calculating means, and a manipulated variable as a result of this comparison calculation. A flow rate control function characterized in that a control means is provided, comprising a proportional distribution multiplier that multiplies the command value of the operating section by a proportional distribution coefficient when the output of the calculation means becomes larger. Hydraulic circuit with.