JPH0247284Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a flow control valve with pressure compensation for meter-in control that controls the flow rate of pressure oil supplied to a hydraulic load (hydraulic device) such as a cylinder to a set value. .

[Prior Art] When operating a cylinder as a hydraulic load, for example, one way to prevent the cylinder piston from running out of control is to control the operating speed of the cylinder by adjusting the flow rate of pressure oil supplied to the cylinder. Meter-in control is being performed.

In that case, for example, a flow control valve with pressure compensation as shown in FIG. 8 is used.

This pressure compensated flow control valve 1 has an inlet port 3 and an outlet port 4 in a body 2, and as shown in FIG. 9, the inlet port 3 is connected to a pressure oil supply source 5, and the outlet port 4 is connected to the supply side oil chamber 6a of the cylinder 6, which is a load operated by hydraulic pressure, and the discharge side oil chamber 6b of the cylinder 6 is connected to the tank 7.
connected to.

An oil passage 10 communicating between the inlet port 3 and the outlet port 4 is formed in the body 2, and a pressure compensation valve 8 is disposed on the upstream side thereof, a flow rate adjustment throttle 9 is disposed on the downstream side, and a pressure oil supply source 5 The pressure oil supplied from the cylinder 6 is caused to flow into the supply side oil chamber 6a of the cylinder 6 via the pressure compensating valve 8 and the flow rate adjusting throttle 9, and its flow rate is controlled.

The pressure compensating valve 8 has a pressure compensating spool 13 fitted into a sliding hole 12 that communicates the inlet port 3 and the oil passage 10, and an oil chamber 12a formed at the left end of the sliding hole 12.
The spool 13 is pushed to the right by the biasing force of the spring 14 provided in the spool 13 and the hydraulic pressure introduced from the outlet port 4 side of the flow rate adjustment throttle 9 through the oil passage 11. On the other hand, a T-shaped oil passage 13a formed in the spool 13 is passed from the inlet port 3 to the oil chamber 12b formed at the right end of the sliding hole 12.
Pressure oil is introduced toward the spool 13, and the spool 13 is pushed to the left by the oil pressure.

Therefore, the pressure compensating spool 13 is located at a position where the pressing forces from both left and right ends are balanced, and the inlet port 3
The opening degree (valve opening degree) x of the annular groove 3a leading to is determined.

The flow rate adjustment throttle 9 is constructed by fitting a spool 17 into a sliding hole 16 that communicates the oil passages 10 and 11 with the outlet port 4, and tightening the position adjustment screw 19 by a spring 18.
It is always in contact with the

A narrow slit (or V-groove) 17b is formed in the land portion 17a of this spool 17, and an orifice 20 is formed between it and the annular groove 4a leading to the outlet port 4. Rotate the position adjustment screw 19 from the spool 17.
It can be set by adjusting the position of.

The pressure compensating valve 8 acts to keep the differential pressure across the flow rate adjustment throttle 9 constant, that is, the pressure difference between the oil passage 10 side and the outlet port 4 side. Even if the oil pressure changes,
The flow rate of pressure oil supplied from the outlet port 4 to the cylinder 6 through the orifice 20 is maintained constant (set value).

[Problem that the invention attempts to solve]

In this way, in conventional pressure-compensated flow control valves, a narrow slit or a V-groove is formed in the spool of the flow rate adjustment throttle to form a throttle orifice, thereby increasing the flow rate adjustment stroke and controlling minute flow rates. This makes it easy to adjust the flow rate in the area.

Therefore, in this part, the viscosity is greatly affected by changes in oil temperature, and the flow rate of pressure oil supplied to the cylinder etc. changes depending on the oil temperature, and the operating speed of the cylinder etc. changes accordingly. There was a problem.

For this reason, some flow rate adjustment orifices are made with acute-angled aperture shapes to make them less susceptible to viscosity, but in the micro flow range, the amount of constriction becomes small and it cannot be said to have an acute-angled shape. Fluctuations in flow rate due to oil temperature were observed.

Furthermore, in the conventional flow control valve with pressure compensation shown in FIG. 8, even if the orifice 20 of the flow rate adjustment throttle 9 is fully closed, leakage occurs between the land portion 17a of the spool 17 and the annular groove 4a. Due to the flow rate
Since Q ₁ occurs, it is necessary to increase the overlap of the fully closed sections to some extent as shown in Fig. 7, which poses the problem of increasing the width of the dead zone.

[Means for solving problems]

The pressure-compensated flow control valve for meter-in control based on this invention solves the above-mentioned problems by incorporating a flow rate adjustment orifice on the upstream side of the oil passage that communicates the inlet port and outlet port of the body, and pressure compensation on the downstream side. In addition to providing a tank port separate from the outlet port, a constriction part that is actively affected by changes in oil viscosity and a pressure compensation valve that maintains a constant differential pressure across the constriction part are installed. Pressure oil is diverted from between a flow rate regulating throttle and a pressure compensating valve in an oil passage that communicates the port and the outlet port, and is returned from the tank port to the tank via the throttle section.

[Effect]

Pressure oil that flows in from the inlet port and passes through the flow rate adjustment restriction is divided into a flow path that passes through the pressure compensation valve and is supplied to the hydraulic load from the outlet port, and a flow path that returns to the tank from the tank port through the restriction section. be done.

Therefore, the viscosity changes with changes in oil temperature,
Even if the amount of pressure oil that flows in from the inlet port and passes through the flow rate adjustment throttle increases or decreases, the throttle part is affected by the change in viscosity and changes the flow rate commensurate with the above increase or decrease. The flow out and supplied to the hydraulic load remains constant.

〔Example〕

Embodiments of this invention will be described below with reference to FIGS. 1 to 6.

Fig. 1 is a cross-sectional view schematically showing an embodiment of this invention, and Fig. 2 is a hydraulic circuit diagram in which the cylinder speed is controlled by the meter-in method as an example of its use. Portions corresponding to those in the figures and FIG. 9 are designated by the same reference numerals, and their explanations will be omitted.

This flow control valve with pressure compensation for meter-in control 1' has a flow rate adjustment throttle 9 on the upstream side of an oil passage 10 that communicates an inlet port 3 and an outlet port 4 formed in a body 2', and a pressure compensation valve 8 on the downstream side. and place the second
Pressure oil supplied from the pressure oil supply source 5 shown in the figure is made to flow into the supply side oil chamber 6a of the cylinder 6 via a flow rate adjustment throttle 9 and a pressure compensation valve 8.

The pressure compensation valve 8 introduces the pressure oil on the inlet side of the orifice 20 of the flow rate regulating throttle valve 9 through the oil passage 23 into the oil chamber 12b on the left end side of the pressure compensation spool 13.
The pressure oil on the outlet side of the orifice 20 is transferred to the oil passages 10 and 24.
Through the oil chamber 1 on the right end side of the pressure compensating spool 13
2a to maintain the differential pressure across the orifice 20 at a set value (compensation pressure).

Furthermore, a tank port 31 is provided in the body 2' in addition to the outlet port 4, and a constriction part 32, for example, in the shape of a capillary (tiyork shape), which is actively affected by changes in the viscosity of oil, is used to maintain a constant differential pressure across the constriction part 32. A second flow rate control section 30 consisting of a pressure compensation valve 33 to maintain
has been established.

Then, the pressure oil separated by the oil passage 37 from between the flow rate adjustment throttle 9 and the pressure compensating valve 8 of the oil passage 10 that communicates the inlet port 3 and the outlet port 4 is transferred to the second flow rate control unit 30. From the tank port 31 to the tank 7 via the pressure compensating valve 33 and the throttle part 32
I am trying to make it flow back to.

Moreover, the pressure compensation valve 33 of the second flow rate control section 30
is the pressure compensating spool 34 as well as the pressure compensating valve 8.
Pressure oil to be supplied to the inlet side of the constriction part 32 is introduced into the oil chamber 36a on the left end side of the pressure compensating spool 34, and the pressure oil supplied to the inlet side of the constriction part 32 is introduced into the oil chamber 36b on the right end side to which the spring 35 is attached. Pressure oil on the outlet side of the is introduced through the oil passage 38 to
It acts to keep the differential pressure across the front and rear constant.

That is, as the temperature of the inflowing pressure oil increases, the viscosity decreases, the resistance of the constriction part 32 decreases, and the differential pressure across it decreases, and the differential pressure between the oil chambers 36a and 36b decreases, so that the pressure Compensation spool 34
moves to the left and the valve opening increases. and,
Since the pressure compensating spool 34 comes to rest when the differential pressure across the throttle portion 32 becomes equal to the set pressure, the flow rate Q ₂ of the pressure oil flowing out from the tank port 31 increases.

On the other hand, when the temperature of the inflowing pressure oil decreases, the viscosity increases, and the resistance of the throttle part 32 increases, so the differential pressure across the throttle part 32 increases, and the oil chambers 36a and 36b
As the differential pressure between the
Q ₂ decreases.

The pressure oil (flow rate Q ₃ ) flowing in from the inlet port 3 and passing through the flow rate adjustment throttle 9 flows out from the outlet port 4 via the pressure compensating valve 8 and enters the cylinder 6.
The flow is divided into the amount flowing into the supply side oil chamber 6a (flow rate Q ₁ ) and the amount flowing back from the tank port 31 to the tank 7 via the second flow rate control unit 30 (flow rate Q ₂ ) (Q ₃ =Q ₁ + _Q2 ).

By the way, as mentioned above, since the orifice 20 of the flow rate adjustment throttle 9 is affected by the viscosity due to the oil temperature, the flow rate _Q3 of the oil flowing therein increases as the oil temperature rises, but this increase is As shown by the curves A, B, C, and D in FIG. 3, even if the set flow rate is increased, the flow rate does not increase significantly, and the flow rate tends to increase almost uniformly in any flow rate setting range.

Therefore, the temperature-flow rate characteristic of the throttle section 32 of the second flow rate control section ₃₀ is set as shown in FIG _. If the flow rate of discharged oil flowing out from outlet port 4 is set to correspond to the increase in
Since Q ₁ is Q ₃ −Q ₂ when Q ₃ > Q ₂ , its temperature-flow characteristics are shown by B', C', and D' in Figure 5, and which set flow rate range Also, there is almost no change in flow rate due to temperature.

That is, the temperature characteristics are significantly improved, and the operating speed of the cylinder 5 is stably controlled by this flow rate _Q1 .

Next, if the opening degree of the orifice 20 of the flow rate adjustment orifice 9 is made extremely small so that Q ₃ <Q ₂ , the flow rate Q ₂ will no longer be able to flow with the differential pressure set by the pressure compensation valve 8, and the differential pressure will increase. In order to
Q ₁ becomes zero.

For example, set the compensation pressure of the pressure compensation valve 8 to 3Kgf/
cm ² , flow rate Q ₂ = 10c.c./min, orifice 2
If the opening amount at 0 is set so that Q ₃ ≧10 c.c./min, the differential pressure before and after the opening is maintained at the compensation pressure of the pressure compensation valve 8 (3 Kgf/cm ² ).

However, by moving the spool 17 to the right using the position adjustment screw 19, the opening amount of the orifice 20 is changed to Q ₃
= 5c.c./min, Q ₂ = 10
Since pressure oil of cc/min must pass through the orifice 20, it cannot flow completely with a differential pressure of 3 kgf/cm ² , so this differential pressure is increased to 12 kgf/cm ² . This is determined from the differential pressure ∝ (flow rate/area) ² .

Since this pressure difference becomes much larger than the compensation pressure, the pressure compensation valve 8 is fully closed.

Therefore, the orifice opening amount and flow rate characteristics with respect to the spool stroke of the flow rate adjustment throttle 9 are determined by the sixth
As shown in the figure, the pressure compensating valve 8 is fully closed until the opening amount of the orifice 20 becomes equal to the flow rate _Q2 , so the width of the dead zone until the flow rate _Q1 starts to flow becomes narrow.

Note that in order to prevent leakage from around the spool 13 of the pressure compensating valve 8, a slight overlap section (dead zone) is necessary.

In this embodiment, the flow rate of the flow rate adjustment throttle 9 is manually set using the adjustment screw 19, but it may be set electrically using a proportional solenoid, a stepping motor, or the like.

In addition, the spool of the flow rate adjustment throttle valve is provided with slits, V-grooves, etc. to form an orifice.
Minute flow rate adjustment can be performed with a relatively long stroke, and there is little variation due to processing accuracy.

In other words, if the machining accuracy of the length of the slit or V-groove is ±0.1, then if the length is 1 mm, it will be ±0.1/1.
= 10 (%), but if it is 3 mm, ±0.1/3 = ±3.3
(%), and the machine difference is reduced.

Furthermore, although not shown in the drawings, if an edge-shaped (acute angle) throttle is formed on the spool instead of a slit or V-groove, fluctuations due to viscosity can be suppressed to some extent, so the throttle part 32 can be formed into a half-edge shape ( The influence of viscosity can be reduced by making the inlet slightly rounded, etc.).

[Effects of the invention] As explained above, the flow control valve with pressure compensation for meter-in control according to this invention prevents the flow rate from decreasing due to the decrease in viscosity even if the temperature of the pressure oil supplied to the hydraulic load such as a cylinder increases. Since the flow rate of pressure oil corresponding to the increased amount can be diverted and returned to the tank via the throttle part of the second flow control section, the flow rate of pressure oil supplied to the hydraulic load can be adjusted without being affected by temperature. The flow rate can be controlled to a preset value using the throttle, thereby making it possible to stably operate a hydraulic device such as a cylinder.

Furthermore, since the dead band width is narrowed, responsiveness is improved in remote operation using a proportional solenoid or the like.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a flow control valve with pressure compensation for meter-out control showing an embodiment of this invention;
Fig. 2 is a hydraulic circuit diagram showing an example of its use, and Figs. 3 to 5 are diagrams showing the characteristics of flow rates Q ₁ , Q ₂ , Q ₃ of each port with respect to oil temperature in the embodiment shown in Fig. 1, respectively. , Figure 6 also shows the orifice opening amount and flow rate Q ₁ for the spool stroke of the flow rate adjustment throttle.
FIG. 7 is a diagram similar to FIG. 6 for a conventional flow rate control valve with pressure compensation; FIG. 8 is a schematic sectional view showing an example of a conventional flow rate control valve with pressure compensation; FIG. 9 is a hydraulic circuit diagram showing an example of its use. 1'...Flow control valve with pressure compensation for meter-in control, 2'...Body, 3...Inlet port, 4...
Outlet port, 5... Pressure oil supply source, 6... Cylinder, 7... Tank, 8... Pressure compensation valve, 9... Flow rate adjustment throttle, 10, 23, 24, 37, 38...
Oil passage, 13...Pressure compensation spool, 17...Spool, 20...Orifice, 30...Second flow rate control section, 31...Tank port, 32...Restriction section, 33...Pressure compensation valve.

Claims (1)

[Claims for Utility Model Registration] 1. The body has an inlet port that connects to a pressure oil supply source and an outlet port that connects to a hydraulic load such as a cylinder, and an oil path that communicates the inlet port and the outlet port with an oil passage that adjusts the flow rate. In the flow control valve with pressure compensation in which a throttle and a pressure compensation valve are inserted, a flow rate adjustment throttle is arranged on the upstream side of the oil passage, a pressure compensation valve is arranged on the downstream side, and a tank port is provided in the body separately from the outlet port. and a throttle part that is actively affected by changes in the viscosity of the oil.
A pressure compensation valve is provided to maintain a constant differential pressure across the throttle, and the pressure oil is diverted from between the flow rate adjustment throttle and the pressure compensation valve of the oil passage communicating the inlet port and the outlet port. A flow control valve with pressure compensation for meter-in control, characterized in that the flow is returned from the tank port to the tank via the tank port. 2. The flow control valve with pressure compensation for meter-in control according to claim 1 of the utility model registration claim, in which the throttle portion is formed in the shape of a thin tube.