JPS6026801A - Flow control circuit - Google Patents

Abstract

PURPOSE:To keep a constant difference in pressure between flows before and behind a flow adjusting variable throttle by incorporating a constant flow control valve, a sequence valve and a fixed orifice in the pilot system of a specific- pressure reducing valve which is connected to the inflow side of the variable throttle. CONSTITUTION:A flow adjusting variable throttle 1 is disposed on the way of a main oil passage 11 which connects a liquid pressure source to a load, such as a cylinder or the like and a specific pressure reducing valve 2 is also arranged in series at the inflow side of the variable throttle 1. A pressure P1 at the entrance of the variable throttle 1 is sent via an oil passage 12 into the primary pilot compartment of said valve 2 and a differential pressure setting spring 10 is provided for the secondary pilot compartment. A constant flow control valve 14 serving for supplying a trifle pilot flow of a constant rate is disposed on the way of an oil passage 13 which connects the inflow side of the specific pressure reducing valve 2 to the secondary pilot compartment. A sequence valve 18 and a fixed throttle 22 making up a parallel circuit are connected to an oil passage 17 which connects the secondary pilot compartment to the outflow side of the variable throttle 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the primary pressure or
・Relates to a flow rate control circuit in which the differential pressure across the variable throttle is kept constant when the secondary pressure fluctuates, and a preset constant flow rate is supplied to the negative part when the throttle opens.

Conventionally, the variable throttle C for adjusting the flow...
There was a drawback that if there was a change in the flow rate, the flow rate would change.

That is, if the flow rate passing through the constriction is Q, the flow IV + coefficient of the constriction part is C1, the opening area of the constriction is Δ, and the density of the fluid is ρ, then the flow rate Q is given by the following formula, Q = CA ffi 10 ( 1) The flow IQ changes depending on the differential pressure ΔP across the throttle.

Therefore, conventional flow control valves combine a throttle valve and a constant differential pressure reducing valve based on the principle that if the differential pressure ΔP before and after the J throttle is kept constant, the flow rate will not change according to equation 1). Even when there is a pressure fluctuation before and after ℃, the differential pressure before and after the throttle is kept constant (the passing flow rate is kept at the set flow rate).

Figure 1 shows the combination of a constant differential pressure reducing valve. ! This figure shows a conventional flow control circuit, which is realized using the valve structure shown in FIG.

In FIG. Bay lower 1 on the next side of valve 2
The input pressure P1 of the variable throttle 1 is introduced into the chamber, and the output force P2 of the variable throttle 1 is introduced into the secondary side pipe I chamber equipped with a pressure setting spring 3. are doing.

Further detailed explanation will be given with reference to the valve structure shown in FIG.
A pressure compensating spool 4 is installed in the flow path from the inlet to the outlet of the body 3, and a pressure compensating spool 4 is installed between the land on the right side of the spool 4 and the inlet passage. 5, and introduce the population pressure P1 of the variable throttle 1 to the right side of the spool 4 to form the primary pilot chamber 7, and on the other side, integrally form a large diameter screw 1 hem 8, Inlet pressure P1 is introduced to the right side of the large-diameter screw 1 hem 8, and a differential pressure setting strip ring 10 is installed in the secondary side piping 1 to chamber 9 on the left side. has been introduced.

As shown in Figures 1 and 2, the operation of the flow rate control circuit Ia, the fluid flow enters from the inlet to the pressure compensating orifice 5 and J:
The inlet pressure 1]1 of the variable throttle '1 reaches the χ outflow L1 which passes through the variable throttle 1 and the variable throttle 1, and the inlet pressure 1]1 of the variable throttle '1 passes through the small hole and flows into the pressure compensation spool 4 A2. The outlet pressure P2 acts on the A3 area, and the outlet pressure P2 acts on the A1 area.

Therefore, if we change the balance of the forces acting on the pressure compensating spool 4 in a steady state where the fluid is flowing, then I
XP2=(A2→-A3) XP1(([4(,
, [is the compression force of the differential pressure setting spring 10), and AI
Since +A2=A3, P'1P2=F/Δ1 (2
), and the front and back difference of variable aperture 1 IEf (r]1-P2
) becomes constant.

Specifically, when the inlet pressure PO changes, the lj force Po
Accordingly, the inflow period from the pressure compensation A refill 5/) port changes (t), the differential pressure across the variable throttle 1 changes, and the balance of the force acting on the L[)J compensation spool 4 is disrupted. That is,
When the inlet pressure Po increases, the pressure horn compensation spool 4 moves to the left, and when the input pressure PO decreases, the pressure compensation spool 4 moves to the right to the balance position.

On the other hand, the output It JF force P2 changes 1. In this case, when the pressure compensating spool 4 becomes unbalanced and the outlet pressure P2 becomes low, the stool 41a moves to the right side, and when the outlet pressure P2 becomes high, it moves to the right side to the balanced position.

As a result, the pressure compensating spool 4 operates as described in (2) above.
It is assumed that the constant difference pressure reducing valve is IrIJI and the flow through the variable throttle 1 is constant so that F/''A1=constant in the equation.

However, in such a conventional flow rate control circuit, the flow m a3 of the pressure compensating orifice 5 of the constant difference pressure reducing valve 2 is determined by the pressure and flow rate of the fluid flowing through the variable restrictor '1.
J, and L "The force also changes, and this change affects the balance based on the differential pressure setting spring 10 of the pressure compensating spool 4, and the front and rear rotation of the variable throttle 1 becomes unstable at a constant value.

To solve this problem, the hydraulic pressure acting area of the pressure horn compensating spool 4 must be △1. A2. Increasing △3 and increasing the spring constant of the differential pressure setting spring 10 is a good idea, but the flow rate used becomes slower and the ail+control valve becomes larger, and the responsiveness decreases as the spool becomes larger. If the differential pressure setting spring is tightened too tightly, the minimum pressure for the constant differential pressure reducing valve to operate will be affected, and when the small flow n1 is set, the differential pressure across the front and rear will fluctuate, causing the passing flow to remain constant. There was a problem that there was no longer a battery.

On the other hand, in the case of 3.1, the decrease in responsiveness can be solved by reducing the area of the flow path of the pyrower 1, but this naturally causes the problem of increasing the size of the valve by 1r1.

The present invention has been made in view of the conventional problems such as (J) (11-force auxiliary spool d3 of the constant-difference pressure reducing valve, the differential pressure setting spring is enlarged, and the front and rear difference of the 61-variable orifice is In addition to keeping the pressure constant within the range of the rated flow rate, the rated flow rate can also be set appropriately depending on the strength of the differential pressure setting spring of the constant A reduction JJ valve. Now, by further increasing the rated flow rate and creating a diversion control circuit that operates stably after setting the small flow suspension, + I + C1j (7 is called 11 white).

In order to achieve this goal, this Komei arranges constant difference pressure reducing valves in a targeted manner on the inflow side of the variable throttle for flow adjustment 11, Constant flow control that applies the input L1 pressure of the variable restrictor to the chamber, and flows a constant flow through the oil path connecting the inlet side oil path of the constant difference pressure reducing valve and the primary side valve 1 to the chamber with a difference INr setting spring. On the other hand, a sequence valve ↑ is installed in the oil path connecting the secondary side pi of the constant differential pressure reducing valve ``1　 and the output of the variable throttle (1), 1-1 pressure is introduced into the 1-1 chamber of the variable restrictor, and the secondary side pipe is equipped with a sequence pressure step-setting spring.
This circuit has a circuit configuration in which a sequence valve is connected in parallel with a fixed A-renoise.

Furthermore, the outflow side oil passage of the constant flow control valve in the circuit is connected to a tank, and a negative
A relief valve that opens at peak pressure when stopped is installed.

If the diversion control circuit tcJ has such a circuit configuration, the differential pressure across the variable throttle will actuate the sequence valve.
A [1~1 pressure is applied, and the front and back Z-pressure decreases 1. : In case (3t), the sequence valve is closed and the fluid flowing through the constant flow control valve a3 and the fixed orifice avoids increasing the secondary side pyroramie pressure of constant differential pressure reduction 5↑, and the spool of the constant differential pressure reducing valve is increased. (The flow rate passing through the throttle is restored to the set flow rate. On the other hand, if the differential pressure across the front and rear increases, the secondary side of the pressure reducing valve is
117 By increasing the force, the spool is squeezed and the flow rate passing through the variable throttle is held down to the set flow rate.
13. J. Install a relief valve in the pilot system ('
By doing this, the increase in circuit 1 "force" of 0 load stop 11''l is suppressed to the relief setting pressure horn.

According to the present invention, the following effects can be obtained.

First, the balance fluctuation of the constant differential pressure reducing valve is eliminated, and the spool is made larger and there is no need to strongly tighten the setting λ shilling 4. Valve, sequence valve J3 and fixed orifice are constant N reduction J
- Since the valve pylon 1 is installed in the oil passage of one system, the valve structure that realizes the flow control circuit can be significantly downsized.

In addition, increasing the spring load to increase the rated flow rate can be achieved by changing the spring load of the sequence valve, so even if the rated flow m is increased, the valve structure does not become larger. By changing the constant differential pressure reducing valve, it is possible to easily increase the constant flow rate by 18 degrees.

Furthermore, Dirii 1'7I1.11. The peak pressure of 'i is held down to the set relief pressure (to protect the circuit, ]' and by the operation of the relino valve, ・fi T mountain 1・:″・11 condition-
[・Moby 1] Tsu 1 - It is possible to improve the stability and response of the circuit by passing a small diversion to the system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a circuit diagram showing one embodiment of the present invention.

First, let's talk about the first configuration! l'Jzuru, liquid ff, BS'
, to the main oil line 11 connected to the load such as the cylinder 9 (,
A variable throttle 1 for adjusting the L flow rate is installed, a force P1 is introduced into the inflow side of the variable throttle 1 via a pilot oil passage 12, and Ml, [setting spring '
10 is installed, and the circuit section is the same as the conventional flow control circuit shown in Figure 1.2. Same (ru1sei wo 4:r
(Jru1゜In addition to this configuration, in the present invention, the inlet side and the primary and secondary side pipes 11 chambers of Maz-jr difference n-1f2)
A constant flow control valve 14 is installed () in which a constant pilot]-small flow 61 flows in the constant flow simple interest (&11 valve i/l 1.L flow rate). The fixed orifice 15 and the constant differential reduction JE tf "I G that determine the Differential pressure i1.5 before and after the throttle 15.
Fixed throttle 15 and constant differential reduction J1 valve +61JcJ
The control to keep the differential pressure across the throttle constant is shown in FIGS. 1 and 2. It has the same effect as the previous flow W control cycle.

On the other hand, the secondary side Byron L-chamber of the constant difference pressure reducing valve 2 and the outflow side 1 of the variable throttle 1. - Oil passage '11 and 5\oil passage 17
1, a non-sequence valve 18 is installed, and the sequence valve 1B's primary side valve, pilot chamber t is 1; In addition, the outlet pressure P2 of the variable throttle 1 is introduced into the secondary side pylower 1 chamber equipped with a differential setting spring 20. Furthermore, a seat valve and a bypass oil A fixed throttle 22 is connected in parallel across the path 21. 1゜Here - C1 A round pressure setting spring 1 that falls on the constant difference pressure reducing valve 2
0's spring in front of the vehicle is equal to or smaller than the conventional device.
The pressure compensating spool used in the L-E valve 2 is also the same as the conventional device (Y, J, a much smaller spool is used).On the other hand, the differential pressure setting spring 20 of the sequence valve 18 is
C is determined according to the rated flow rate of the variable restrictor '1, and when increasing the rated flow rate (spring sufficiently spring VJG>
, l-1 is short; JEL [n2 constant spring 20
4 Use.

Next, the operation of the embodiment shown in FIG. 3 will be explained.

Set the opening degree of variable aperture 1 WI3 ffi is jri 1
', -,,, while listening to the flow, let the fluid flow through the oil passage 11, and (when the time comes, e.g. Power [) 2 change point]
J 9 When the differential pressure △1) (-Pl-P, 2) at the front and rear of Calibration 1 decreases, the front and rear pressure ΔP is J, and the force applied to the resequence valve 18 is the difference jl. 20 spring force 1:1 or more]・Tomuttosa 1 piece sequence valve 18
is shown in the figure, Jζ) (two closed, bypass oil passage 2) ()
A constant flow control valve 'l/l (,
: J, a constant flow rate q1 flows, and this constant flow rate +111
．． 1) Occurrence of fixed orifice 22 9 Ii', -C constant; decrease j [Pressure 1' in the secondary side pyrower 1-chamber of valve 2 rises L, decreases constant 7' 11 valve 2 Pressure compensation spool IJ Ii
Move and balance in the direction of listening to Rikiura 1nΔ Rinois,
As a result, the flow m flowing into the variable A refill 1 is increased, and the differential pressure ΔF across C is restored to a constant value corresponding to the set flow rate.

Next, if the increase in the input January-January force P O is 2 < lJl i
, lf l', I Ll Variable aperture 1 due to decrease of force P2
Suppose that the differential pressure ΔP (= "1 - P 2 ) across the front and rear increases, the force acting on the sequence valve 18 according to the differential pressure Δ
1-same), the sequence valve 18 switches to listen to the oil path, and a constant flow from the control valve 14 (11 flows through the sequence valve 1ε3. Therefore, a constant differential pressure reduction occurs. valve 2
secondary side pilot]・The pressure in the chamber decreases, and the constant differential pressure reducing valve 2
Move the 1ri spool of pressure oil to the force side that closes the oil pressure (balanced), and therefore the flow rate flowing through the variable restrictor 1 is restricted (the differential pressure △P before and after is adjusted according to the set flow rate). (I will hold it down to a constant value).

The difference between the front and rear of the variable throttle 1 is controlled by controlling the secondary piping pressure of the constant differential pressure reduction jt2 by the operation of the sheath valve 18 according to the external pressure Δt1 of the front and rear of the variable throttle 1. The pressure ΔP is always kept constant, and the input "1 pressure PO or output"
When the pressure P2 fluctuates, variable throttle 1 is applied to the cylinder load cap.
A fixed flow IF can be provided.

In addition, the secondary side pipe of the constant difference pressure reducing valve 2 is installed independently from the Tsuchiura Road 11.
Since it is controlled by
There is no need to strengthen the valve 0 or increase the hydraulic action area of the pressure compensating spool. I can do it.

Furthermore, the rated flow rate setting IJ corresponding to the maximum flow W, constant differential pressure reduction tf2, by controlling the differential pressure △P before and after the variable throttle 10 to be constant.
This can be achieved by increasing the spring MffiF1 of the differential pressure setting spring 20 in the sequence valve 18 by increasing the pressure setting reset spring 10. is constant flow M control valve 1
A small flow rate q1 is caused by 4 (since j,
Since the tank valve 1 B itself has been made smaller, the spring load of the differential pressure setting springs 2 and 0 should be set to 1.
/'U There is no need to enlarge the valve structure, and even if the rated flow rate is increased, the control circuit (J) can be made smaller.

This + j Because of this, it is possible to replace the constant flow control valve 14, the fixed flow control valve 14, the fixed flow control valve 14, the fixed flow control valve 14, and the fixed flow control valve 22 with a small one. Even if the control circuit is provided, the control circuit will be downsized by fd, and the spring load "
By using a small one with 0, a small diversion can be set with iiJ variable aperture 1.

However, it is possible to perform high-precision control to always maintain the differential pressure Δ() between the front and rear constant.

FIG. 4 is a circuit diagram showing another embodiment of the present invention,
This embodiment is based on the oil passage 1 on the outflow side of the constant flow control valve 14 shown in FIG. '3 is equipped with a lilin valve 24 (), and the tank 25 is
It is characterized in that it is connected to the circuit of the song (16 or the embodiment shown in FIG. 3).

In this embodiment of FIG. 5, 1. Burnt (', also lily) valve 2
/I is when the cylinder load is at full stroke 1-], and tl moves from the cylinder end to the end of the cylinder. JJ on the primary side of the external pressure reducing valve 2
II 4'> Prevent +L l, , Constant differential pressure reducing valve 24
One special feature is that it is set to (l? if) from the peak chromatic force at 1 load f￥11. A constant flow II h<jl 677 is supplied to the cylinder, and when it reaches the cylinder end, the Lt flow reaches U days and the pressure in the circuit reaches the 11 output pressure of liquid J1.1lNi. When the pressure reaches the relief setting pressure of λ1 and the relief pressure setting spring 26 reaches a certain value, the relief valve 24 opens and communicates with the tank 25.
Pressure in the circuit is suppressed to the relief setting pressure. At this time,
11 Constant flow in the relief valve 24 m Control valve '14 cJζ constant small flow resistance q1 and constant differential pressure reduction 11゛2 and small flow jj'i due to leakage of variable throttle 1, +12 is fixed Δ refit 22
C flows through.

In this case, the primary side bar (1:
, 1 1 - Pressure Which downstream pilot pressure Difference j - [
is a relatively low difference set by the setting spring 10C.
It is possible to protect the constant differential pressure reducing valve 2 from the peak I which occurs at t4 when the load is stopped.

Of course, the relief valves 211 and C are sufficiently miniaturized because the constant flow control valve 14 has a small flow rate (11, the constant difference pressure reducing valve 2, and the leakage flow from the variable throttle 1 [fiQ2]). and newly installed the relief valve 24 ()-U (,
+ The valve device can be sufficiently miniaturized.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional circuit, and Figure 2 is an i! FIG. 3 is a sectional view showing an example of a conventional valve structure; FIG. 3 is a circuit diagram showing an embodiment of the I* invention; FIG. 1: Variable throttle for flow rate adjustment 2, 'IC3: Constant difference pressure reducing valve 1o, 17; 20 nibui 1 pressure stage constant snow 'link' + 1
: ff2 oil passage 2.19: Pi II oil passage 13.17: Oil passage 15.22: Fixed throttle 18: Sealing valve 2'l: Bypass oil passage 2I! I: Relief valve 25): Evening 26: Relief setting pressure spring Fig. 1 0 Fig. 2

Claims (2)

[Claims] (1) Variable throttle for flow adjustment, etc. Arranged in series on the inflow side of the variable throttle for flow adjustment, if
Insertion of variable orifice] Primary side pie where pressure is introduced ['' 1-
The secondary side pipe containing the chamber, 13 and the differential pressure setting spring [
``TS1''~The constant difference i1i, li L, which moves the chamber to the right, [with the valve,
A constant flow control valve that is installed in an oil passage connecting the inlet side oil passage of the constant difference pressure reducing valve and the secondary side pilot chamber, and a constant flow control valve that flows a constant flow, and a secondary side piping [J tube] of the constant difference pressure reducing valve. 1 chamber and said iiJ
It was installed in the oil passage connecting the outlet side oil passage of the variable throttle, and introduced the inlet pressure of the variable throttle into the primary pilot chamber 1~, and the fHl:] pressure into the secondary side pylon 1~chamber with a setting spring. A flow control circuit comprising a sequence valve and a fixed throttle connected in parallel to the sequence valve. (2) A variable throttle for flow rate adjustment, a primary side bi-III chamber into which the input L1 pressure of the variable restrictor is introduced, and a differential pressure setting spring are provided. A constant flow control valve installed in an oil passage connecting the inflow side oil passage of the constant difference pressure reducing valve and the secondary side piping chamber, and a constant flow rate control valve that flows a constant flow, The secondary side pipe of the differential pressure reducing valve is provided in the oil passage connecting the J chamber and the output (1 side oil passage) of the variable throttle, and the artificial pressure horn of the variable throttle is connected to the primary side pilot chamber, and the outlet pressure A sequence valve introduced into the chamber on the secondary side equipped with a differential pressure setting spring, a fixed throttle connected in parallel to the sequence valve, and a fixed throttle connected in parallel to the sequence valve, as defined above))! A diversion control circuit characterized in that it is equipped with a relief valve installed in an oil path leading from the outflow side of the sub-control valve to the tank.