JPH03157503A - Hydraulic circuit having flow rate controlling function - Google Patents

Abstract

PURPOSE:To facilitate operation by detecting a grand total of oil required by a load from the operational rate of directional changeover valves provided with pressure compensation valves on the downstream side thereof, comparing the grand total of oil with a discharge oil rate of a hydraulic pump, and according to the obtained result, multiplying the command value of the operational parts by a coefficient. CONSTITUTION:Operational command signals of a control means 30 are inputted to operational parts 5b, 5c to 7b, 7c of solenoid type directional changeover valves 5a to 7a arranged between a hydraulic pump 1 and actuators 20 to 22. 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 1b are inputted to the control means 30. The control means 30 compares the grand total of flow rate of pressure oil required by a load with the discharge rate of the hydraulic pump 1, and according to the obtained result, multiply the command value of the operational parts by a coefficient of a proportional distribution for outputting. 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 of 1111 m is shown in Fig. 4 (
The hydraulic circuit diagram disclosed in Japanese Patent Application Laid-Open No. 188504/1982 is rewritten as a hydraulic circuit.

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

In this hydraulic pump l, the tilting angle of the swash plate 2 is controlled by the output of the hydraulic cylinder If serving as a discharge flow rate control section, and the discharge flow rate discharged to the main circuit 4 is changed by the tilt angle of the swash plate. It has become.

The hydraulic cylinder 1f has a pressure chamber 1b connected to the pilot circuit 14 and a spring 1c, and when no pressure oil acts on the pressure chamber 1b, the rod ld is held at the illustrated position by the spring 1c. 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 or more 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 10 to 12.

The pressure compensating valve 10 has 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 Job. When the difference between the pressing forces between the spring chamber 10b and the pressure chamber 10c increases, the pressure compensating valve 10 moves its main valve 10d largely to the left from the position shown in the figure. Increase the amount of WO connections. Conversely, when the difference between the pressing forces between the spring chamber Job and the pressure chamber 10c becomes smaller, the amount of movement of the main valve 10d to the left from the illustrated position is reduced, and the amount of connection between the directional control valve 5 and the load WO is reduced. Make it smaller. (Please note that the pressure compensation valve 11.
12 has the same structure as the pressure compensating valve 10, so for the same parts of the pressure compensating valves 10 to 12, only the numbers are indicated by adding the same alphabetical suffix to the numbers 11 and 12 representing the respective pressure compensating valves. The explanation will be omitted. ) Hydraulic cylinder 1 of hydraulic pump l and spring chamber 1 of pressure compensation valves 10 to 12 (l
The pilot circuit 14 connected to b to 12b is connected to the output side of the high voltage selection circuit 15. This high voltage selection circuit 15 selects the high voltage side of the load circuit 20 to which the load Wl is connected, and the output side thereof is the high voltage selection circuit 1.
The pilot circuit 14 is connected to the output side of the selection valve 17. Therefore, the pilot circuit 14 has loads WO to W.
The pressure of the highest value of the load pressure in the load circuits 20 to 21 to 2 is applied.

The conventional hydraulic circuit having a flow rate control function having the above configuration applies a load pressure corresponding to the highest load among the loads WO to W2 to the spring chambers tob to 12b of the pressure compensation valves 10 to 12 via the pilot circuit 14. Let it work. Further, the hydraulic pressure of the pilot circuit 14 is applied to the pressure chamber 1b of the hydraulic cylinder 1f, and the discharge hydraulic pressure of the hydraulic pump l is applied to 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, the directional control valve 5 and the directional control valve 6
When the is operated, the oil pressure on the upstream side of the pressure compensation valve 10 and the pressure compensation valve 11 increases depending on the opening degree, and the oil pressure becomes as follows.
It acts on the pressure chamber 10c and the pressure chamber 11c via the pilot circuit 13a and the pilot circuit 13b. Then, the main valve 10d of the pressure compensation valve 10 connects the pressure chamber Inc and the spring chamber 10.
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 switching valve 5 and the directional switching valve 6 is maintained at a constant value of the pressing force of the spring LOa and the spring Lla, and the load WO1 and the load W
The amount of oil supplied to l is set to a value corresponding to the operation amount of the directional switching valve 5 and the directional switching valve 6. Note that the same applies when all of the directional control valves 5 to 7 are operated, so a description thereof will be omitted.

[Problem that the invention seeks to solve]

In the above conventional technology, the pressure compensating valves 10 to 12 adjust the pressure on the downstream side of the directional control valves 5 to 7 to the highest oil pressure among the loads wo to w2, and a higher oil pressure is generated in the hydraulic pump l. By determining the discharge flow rate of the pressure oil, the differential pressure before and after the directional valves 5 to 7 is kept constant, and the pressure is applied to the load W It distributes oil. This action occurs when the amount of oil required by the loads WO to W2 exceeds the amount of oil discharged from the hydraulic pump l, the pilot circuits 13a to 1j on the upstream side of the pressure compensation valves IO to 12
The oil pressure of b decreases depending on the amount of operation of the directional control valves 5 to 7. Therefore, the main valve 10d~ of the pressure compensation valve lO~12
12d is moved by springs 10a-12a.

Therefore, the operation of the pressure compensation valves 10 to 12 is limited to the springs 10a to 12.
Affected by 12a.

Due to the above reasons, when the amount of oil required by the loads WO~W2 is smaller than the amount of oil discharged from the hydraulic pump 1, the hydraulic circuit that controls the flow 41 operates in the upstream pilot circuit 13a of the pressure compensation valves 1O~12. Since the oil pressure of ~13b can be secured, the distribution ratio becomes a value corresponding to the operation amount of the directional control valves 5-7. However, when the amount of oil required by the load WO-W2 is larger than the amount of oil discharged from the hydraulic pump, even if the directional control valves 5 to 7 have the same operation amount, the springs 1 (la to 12) of the pressure compensating valves 10 to 12
As the amount of deflection of a changes, the differential pressure before and after the directional control valves 5 to 7 changes, and therefore the oil amount distribution ratio to the load changes. Therefore, for the operation command value of the directional valve, the load WO~
There is a problem that the operation of W2 does 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 connect a load such as an actuator to the discharge side of a variable discharge hydraulic pump having a discharge flow rate control section. A pressure compensation system in which a plurality of switching valves are provided, and on the downstream side of the directional switching valves, a main valve pressed in the closing direction by a spring, a spring chamber in which the spring is built in, and a pressure chamber are arranged via the main valve. In addition to providing a selection circuit for selecting the highest value of load pressure in the load circuit of the load connected to each of the directional control valves, the pressure chamber of the pressure compensation valve is connected to the downstream side of the directional control valve, and a spring A chamber is connected to the output side of the selection circuit, the output side of the selection circuit is connected to a discharge flow rate control section of the hydraulic pump, and the discharge flow rate of the hydraulic pump is connected to the directional switching valves on each side. In a hydraulic circuit having a flow control function configured to control the amount of oil to the required amount of the load, and distribute the amount of oil discharged from the hydraulic pump to each load using the pressure compensation valve and the directional control valve, or a fixed amount. A plurality of directional switching valves connected to loads such as actuators are provided on the discharge side of a discharge type hydraulic pump, and a main valve that is pressed in the closing direction by a spring and a main valve connected to the downstream side of the directional switching valve are connected to each other via the main valve. A pressure compensating valve is provided in which a spring chamber in which the spring is incorporated and a pressure chamber are arranged, and a selection circuit for selecting the highest value of load pressure is provided in a load circuit of a load connected to each of the directional switching valves, The pressure chamber of the pressure compensation valve is connected to the downstream side of the directional control valve, and the spring chamber is connected to the output side of the selection circuit, and the selection circuit is connected 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 circuit is connected and a bleed-off pressure control valve opposed to this spring chamber via a main valve and connected to the main circuit are provided, and this bleed-off pressure compensation valve controls the discharge hydraulic pressure of the hydraulic pump. is held high by a certain value by the load pressure of the directional valve mentioned above,
In a hydraulic circuit having a flow rate control function configured to distribute the amount of oil discharged from the hydraulic pump to each load using the directional switching valve and the pressure compensation valve, the directional switching valve is an electromagnetically operated directional control valve. A switching valve, and a discharge flow rate calculating 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 discharge flow rate calculating means for calculating the discharge flow rate of the hydraulic pump, between the operating part of the electromagnetically operated directional selector valve and the operating device for the electromagnetically operated directional selector valve. operation amount calculation means for calculating the total flow rate required by the load from the sum total of the operation amounts of the electromagnetically operated directional control valve; and a comparison operation for comparing the output of the discharge flow rate calculation means and the output of the operation amount calculation means. When the output of the operation amount calculation means becomes larger as a result of this comparison operation,
The present invention is characterized in that a control means is provided, which includes a proportional distribution multiplier that multiplies the command value of the operating section by a proportional distribution coefficient.

[Operation] The present invention having the above-mentioned technical means is capable of reducing the amount of oil discharged from the hydraulic pump when the directional control valve is operated in excess of the amount of oil discharged from the hydraulic pump, or when the load fluctuates during operation of the directional control valve. When the amount is insufficient, the control means changes the operating amount of the directional valve proportionally to match the amount of oil discharged from the hydraulic pump, and the pressure compensating valve is not varied. Therefore, even if the amount of oil supplied to the loads WO to W2 becomes necessary in excess of the discharge flow rate of the hydraulic pump, the amount of oil supplied to the loads WO to W2 is reliably proportional to the original operation amount. Becomes a value.

〔Example〕

The first embodiment of the present invention is shown in FIG. 1 (A) and FIG. 2 (A) below.
, will be explained with reference to FIG. In addition, when explaining,
Only the points that are different from the conventional technology will be explained.

In the embodiment shown in FIG. 1(A) and the conventional technology shown in FIG. A control means is provided, and the control means controls the pressure chamber 1b of the hydraulic cylinder 1f of the variable discharge type hydraulic pump in FIG. 1(A).
The hydraulic pressure of the pilot circuit 14 connected to is converted into an electric signal and applied to the control means 30.

In addition, the operating portions 5b of the electromagnetically operated directional control valves 5a to 7a,
5c to 7b, 7c send the operating signals Sl to the operating device 31.
S3 is connected via the control means 30 so as to be given S3.

The rotational speed n of the engine 3 that drives the hydraulic pump 1 and the oil pressure in the pressure chamber tb are converted into an electric signal P and input to the other control means 30.

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 or in the center position, the operating part 5b of the directional control valve 5a
No operation command is issued to the handle 3.
When 1a is operated in the direction of the arrow, switch 32a switches to the contact side.

An operation command corresponding to the amount of operation 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 to the operating section 5c is transmitted to the handle 31.
As much as the amount of operation of a! It is now applied. Further, the output signal of the operating device 3 is applied to a multiplexer 33 of the control means 30.

The pressure chamber 1b of the hydraulic cylinder If serving as the discharge flow rate control unit of the hydraulic pump I and the output signal of the engine 3 are applied to a function circuit 34 that calculates the discharge oil amount Q of the hydraulic pump 1 from these two values. , is applied to the multiplexer 33 as discharge oil ftQ of the hydraulic bomb l. The analog signals applied to these multiplexers 33 are applied to the arithmetic unit 36 via the A-D converter 35, and are applied to the operating units 5b, 5 of the directional control valves 58-7a via the interface 37.
Applied to c~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 Ql to Q3 to be passed through each directional control valve is calculated. A manipulated variable calculation means 40 that calculates the total load oil amount Qv required by the loads WO to W2 from the added value.
and a discharge oil amount calculation means 41 that 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 the hydraulic pump l
Subtract the load WO~W2 or the required load oil amount Qv from p, and if the value Qc (oil amount Qp - oil amount Qv - Qc) is negative (value Qc<O), the manipulated variable operator is 0). It is composed of a comparison calculation means 42 which issues a command to the operation amount calculation means 44.

In addition, when the output of the comparison calculation means 42 becomes a negative value, the operation amount operator stage 43 inputs the oil amount required by each load calculated from the operation command signals S1 to S3 to the operation command signals S1 to S3. The operation command signals Sl' to S2' obtained by correcting the product of Ql to Q3 and Qp/Qv are applied to the operating portions 5b, 5c to 7b, and 7c of the directional control valves 5a to 7a, and are operated by the operation amount calculation means. 44 is when the output of the comparison calculation means 42 becomes 0 or a positive value, so the operation command signal s
Directional switching valves 5a to 7a with the signals of 1 to s3 as they are.
The voltage is applied to the operating units 5b, 5c to 7b, and 7c.

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

As mentioned above, the hydraulic circuit shown in FIG. 1(A) maintains the discharge oil pressure of the hydraulic pump l at a constant pressure difference between the upstream side and the downstream side of the pressure compensation valves 10 to 12 or the directional control valves 58 to 7a. The amount of oil to loads WO to W2 is maintained at the value of directional control valve 5.
The amount of oil corresponding to the operation amount of a to 7a is supplied.

In the above-described operation of the hydraulic circuit, the control means 3° functions as follows. For example, assuming that a command to operate the directional control valves 5a to 7a is being transmitted, the handles 318 to 3 of the operating device 31 that transmit the commands to operate the valves 5a to 7a.
The command value 1c is applied to the multiplexer 33, which converts the pilot hydraulic pressure of the pilot circuit 14 acting on the pressure chamber lb of the hydraulic cylinder 1a into electricity and applies it to the function circuit 34 as a hydraulic signal p. A function circuit 34 converts the rotation speed into an electrical signal and uses it as a rotation speed signal n.
to be applied. The function circuit 34 calculates the discharge oil ff1Q of the hydraulic pump 1 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 sequentially detected by three multiplexers,
The detected analog signal is applied as a digital signal to the arithmetic unit 35 via the A-D converter 35. When the operation signal SL of the joystick handle 31a of the operation device 31, the operation signal S2 of the joystick handle 31b, and the operation signal s3 of the joystick handle 31c are sequentially detected by the multiplexer 33, the calculation device 36 calculates the operation amount. The calculation means 40 operates the directional switching valve 5a and the directional switching valve 7a based on the operation signals Sl to s3.
Load oil amount Qv to be supplied to loads WO to W2
Calculate. Further, when a 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 amount signal Q.

The discharge oil amount Qp and the load oil amount Qv are calculated by the comparison calculation means 4
In step 2, the load oil amount Qv is subtracted from the discharge oil amount Qp, and the value is less than 0/(Qp-Qv≧0), and the load WO~
Since the amount of oil discharged from the hydraulic pump l exceeds the amount of oil required by W2, the operation amount operator stage 44 outputs the operation signal 5 from the operation device 31 to the directional control valves 58 to 7a.
A signal equivalent to l-S3 is applied to the operating section 5b or 5c of the directional switching valve 5a, the operating section 6b or 6c of the directional switching valve 6a, and the operating section 7b or 7c of the directional switching valve 7a. In this way, when the operation command is applied to the directional switching valves 58 to 7a, the pressure compensating valves 10 to 12 adjust the difference between the front and back of the directional switching valves 5a to 7a, as described above. The pressure is controlled to maintain the loads WO to W2 at values corresponding to the operating amounts of the directional switching valves 5a to 7a.

In the above operation, as a result of operating the operation device 31 and increasing the operation signal Sl, the load oil amount Qv calculated by the operation amount calculation means 40 increases and becomes smaller than 0 as the calculation result of the comparison calculation means 42 (Qp -Qv<O), and the operation signal S1' is smaller than the operation signal S1 obtained by multiplying the load oil amount Q1 corresponding to the operation signal S1 by the value of discharge oil ff1Qp/load oil amount Qv. The voltage is applied to the operating portion 5b of the directional control valve 5a. Similarly, the computing unit 43b
is the discharge oil amount Q to the load oil amount Q2 corresponding to the operation signal S2.
The product is multiplied by the value of p/load oil amount Qv and applied to the operating section 6b of the directional control valve 6a as an operating signal S2' smaller than the operating signal S2, and the arithmetic unit 43c also applies an operating signal S3' to the operating section 7b. Therefore, the operating amounts of the directional switching valves 58 to 7a are reduced in proportion to the operating amounts of the operating device 31 until they become equal to the amount of oil discharged from the hydraulic pump l, so the speeds of the loads WO to W2 are reduced. However, the operation amount of the operation part gt:ll, that is, the joystick handle:lla,
The operation continues at a speed proportional to the amount of operation of 31b and 31c. In addition, joystick handle: 11a
, 31b, :lIc are operated, they continue to operate at the same speed ratio.

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

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

The bleed-off type pressure compensation valve 8 is composed of a spring chamber 8b having a spring 8a and a pressure chamber 8c disposed in the spring chamber 8b via a main valve 8d.
b is connected to the pilot circuit 14, and the pressure chamber 8c is connected to the main circuit 4 via the pilot circuit 8e.

Note that the relief valve 8f limits the maximum pressure of the pilot circuit 8e.

Bleed-off type pressure compensation valve 8 having such a configuration
is maintained higher than the hydraulic pressure of the pilot circuit 14 acting on the spring chamber 8b by the pressing force of the spring 8a. In other words, the hydraulic pressure of the main circuit 4 is determined by the load pressure of the loads WO to W2.
The value is held at a higher value by the amount of pressing force. The oil pressure in the main circuit 4 maintained at such oil pressure is applied to the load WO connected to each of the directional control valves 58 to 7a by the pressure compensating valves lO to 12.
~W2, and supplies hydraulic pressure according to the operation amount of the directional control valves 5a to 7a to the loads WO to W2.

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

The operations of the multiplexer 33, AD 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 5a 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 5a to 7a.
The comparison calculation means 42 subtracts the load oil amount Qv from the discharged oil amount Qp, and if the value Qc is smaller than O, the manipulated variable operator stage 43 calculates the amount Qp. The manipulated variables 51 to s3 are multiplied by the discharge oil amount Qp/loaded oil amount Qv to obtain the corrected manipulated variable signals Sl'' to S3', and the amount of throttle formed by the directional switching valves 5a to 7a is switched in each direction. The load oil amount Qv passing through the valves 5a to 7a is corrected to match the discharge oil amount Qp of the hydraulic pump Ia. Therefore,
The pressure compensation valves 23 to 25 do not operate, and the load WO
Hydraulic pump for W2! Since the discharge pressure oil of a is distributed proportionally, the amount of oil required by the loads WO to W2 is the same as that of the hydraulic pump 1aA.
The ratio of change in operating speed of the loads WO to W2 remains the same when the discharged oil amount is exceeded and when it is not exceeded.

(Effects of the Invention) As explained above, the present invention detects the load or the total amount of pressure oil required from the operation amount of the directional control valve, and detects the discharge oil of the hydraulic pump from the hydraulic pump control oil pressure and the engine rotation speed. When the amounts are compared and calculated, and the total amount of pressure oil required is greater than the amount of oil discharged from the hydraulic pump due to the operation amount of the directional control valve,
The operation signal to each directional switching valve is controlled according to the operating amount of the directional switching valve so that the total amount of pressure oil required for the load matches 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, does the operating speed of the load decrease?What is the ratio 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 greater than the amount of oil discharged by the hydraulic pump from the operation amount of the directional valve, the operator can adjust the hydraulic pressure without changing the amount of operation of each directional valve. This has the effect of making the operation easier because the operation can be performed with the same feeling as when the total amount of pressure oil required is smaller than the amount of oil discharged from the pump due to the amount of operation of the directional valve.

[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, FIG. 1(B) is a hydraulic circuit diagram including an electrical system according to a second embodiment of the present invention, and FIG. 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, and Figure 3 is the control system diagram of the control means of the second embodiment.
B) a block diagram showing the flow of functions of the arithmetic device;
FIG. 4 is a hydraulic circuit diagram of the prior art. l...Variable discharge type hydraulic pump la...Fixed discharge type hydraulic pump 3...Engine 4...Main circuit 5a, 6a, 7a...Direction switching valve 8... Bleed-off type pressure compensation valve 9...Hydraulic-electrical converter lO~12...Pressure compensation valve 14...Pilot circuit 15...High pressure selection circuit 16.17...Selection Valve 20-22...Load circuit 30...Control means]...Operating device 32...Switch 33...Multiplexer 34...Function circuit 35...A -D converter 36... @ Calculation device 40... Manipulated amount calculation means 41... Discharge amount calculation means 42... Comparison means 43, 44... Manipulated amount calculation means 4 pieces a, 4 go a, 43a...Arithmetic unit 1 diagram (A
)

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 hydraulic pump having a discharge flow rate control section, and a valve is pressed in the closing direction by a spring on the downstream side of the directional switching valve. A pressure compensating valve is provided, which is composed of a main valve, a spring chamber in which the spring is built in, and a pressure chamber arranged through the main surface of the main valve. A selection circuit for selecting a value is provided, a pressure chamber of the pressure compensating valve is connected to the downstream side of the directional control valve, a spring chamber is connected to the output side of the selection circuit, and the output side of the selection circuit is connected to the output side of the selection circuit. connected to a discharge flow rate control section of a hydraulic pump, controls the discharge flow rate of this hydraulic pump to the required oil amount for the load connected to the individual directional switching valve, and adjusts the discharge oil amount of the hydraulic pump to the pressure compensating valve. In a hydraulic circuit having a flow control function configured to distribute the flow rate to each load with a directional control valve, the directional control valve is an electromagnetically operated directional control valve, and the operating part of the electromagnetically operated directional control valve and , a discharge flow rate calculation means for calculating the discharge flow rate of the hydraulic pump is provided between the operating device for the electromagnetically operated directional control valve, and a load is required from the sum of the operating amounts of each of the electromagnetically operated directional control valves. a manipulated variable calculation means for calculating the sum of the flow rates, a comparison calculation means for comparing the output of the discharge flow rate calculation means with an output of the manipulated variable calculation means, and an output of the manipulated variable calculation means as a result of this comparison calculation. 1. A hydraulic circuit having 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 coefficient of proportional distribution when the command value becomes large. (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 on the downstream side of the directional switching valves, there is a main valve that is pressed in the closing direction by a spring and a main valve that is pressed in the closing direction by a spring. A selection circuit for selecting a maximum value of load pressure for a load circuit of a load connected to each of the directional control valves, and providing a pressure compensation valve in which a spring chamber in which the spring is housed and a pressure chamber are arranged via a valve. is provided, the pressure chamber of the pressure compensation valve is connected to the downstream side of the directional control valve, the spring chamber is connected to the output side of the selection circuit, and the pressure chamber is connected to the output side of the selection circuit, and 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-off pressure control valve opposed to this spring chamber via a main valve and connected to the main circuit are provided, and the bleed-off pressure compensation valve controls the hydraulic pressure. A configuration in which the hydraulic pressure discharged from the pump is held high by a certain value by the load pressure of the directional switching valve, and the amount of oil discharged from the hydraulic pump is distributed to each load by the individual directional switching valve and pressure compensation valve. In a hydraulic circuit having a flow rate control function, the directional control valve is an electromagnetically operated directional control valve, and an operating section of the electromagnetically operated directional control valve, and an operating device for the electromagnetically operated directional control valve. a discharge flow rate calculating means for calculating the discharge flow rate of the hydraulic pump; and a manipulated variable calculating means for calculating the sum of the flow rate required by the load from the sum of the manipulated variables of each of the electromagnetically operated directional control valves; , a comparison calculation means for comparing the output of the discharge flow rate calculation means and the output of the operation amount calculation means, and when the output of the operation amount calculation means becomes larger as a result of this comparison calculation, the command value of the operation unit is 1. A hydraulic circuit having a flow rate control function, characterized in that a control means is provided, comprising a proportional distribution multiplier for multiplying a proportional distribution coefficient by a proportional distribution coefficient.