CN106907367A - New Structure Speed Control Valve - Google Patents

Abstract

The invention discloses a novel speed regulating valve, the flow rate controlled by the valve is not affected by the change of load at all, and the problem of the speed stability of the hydraulic cylinder under the condition of changing load is solved. The principle is to set a reset plunger to replace the original reset spring on the basis of the existing speed control valve, and lead the pressure oil from the oil inlet of the speed control valve to the end chamber of the reset plunger through the oil hole two so that the spool of the pressure reducing valve is always subject to a constant hydraulic pressure, even when the position of the spool of the pressure reducing valve changes due to feedback, the thrust generated by the hydraulic oil acting on the end of the reset plunger remains unchanged. This ensures that the pressure difference between the front and rear of the orifice remains unchanged. At the same time, in order to ensure that the acting area of the hydraulic oil at both ends of the pressure reducing valve spool is equal, an area compensation plunger is set at the other end of the pressure reducing valve spool, and the cross-sectional area of the area compensation plunger is equal to that of the reset plunger. equal. The present invention overcomes the inherent defect of the original spring reset, ensures that the pressure difference between the front and rear of the orifice remains unchanged, and when the area of the orifice is constant, the flow rate flowing through the speed regulating valve is not affected by the load change at all, thereby ensuring The speed control accuracy of the hydraulic cylinder is improved.

Description

New Speed Control Valve

technical field

The invention relates to the technical field of a speed regulating valve for controlling liquid flow, in particular to a novel speed regulating valve whose flow does not vary with load.

Background technique

In order to control the movement speed of the hydraulic cylinder, the throttle valve is the simplest and most basic flow control valve, but due to the poor rigidity of the throttle valve, it is only suitable for occasions where the load changes little or the speed control accuracy is not high . The pressure-flow equation Q=C _d A (2ΔP/ρ) ^1/2 of the well-known orifice shows that the flow rate through the orifice is proportional to the opening area A of the orifice, and is proportional to the pressure difference between the front and rear of the orifice. The half of ΔP is directly proportional to the power. In order to ensure that the flow Q remains unchanged, it is only necessary to ensure that A and ΔP remain unchanged. Therefore, in order to solve the problem of the speed stability of the hydraulic cylinder with large load changes, after the opening area A of the throttle port is adjusted, measures should be taken to ensure that the pressure difference between the front and rear of the throttle valve port remains unchanged when the load changes.

The currently known technology is a speed regulating valve composed of a throttle valve and a differential pressure reducing valve connected in series, and an overflow throttle valve composed of a throttle valve and a differential pressure relief valve in parallel. The principle of these two valves is to use the spool movement of the fixed differential pressure reducing valve and the differential pressure relief valve to compensate the pressure difference change before and after the throttle port, so as to ensure the front of the throttle valve port. , After the pressure difference is basically unchanged.

According to the known speed regulating valve, its principle is to lead the pressure oil before and after the throttle port to the two ends of the differential pressure reducing valve core respectively, and the difference between the hydraulic thrust generated by the pressure difference and the elastic force of the spring and the hydraulic force Balance, that is, the hydraulic thrust generated by the pressure difference is equal to the spring force minus the hydraulic force. If the load is constant, the spool of the fixed difference pressure reducing valve works stably in a balanced position, and the opening of the spool of the fixed difference pressure reducing valve is constant. When the outlet pressure of the orifice changes with the load, the force balance of the spool of the differential pressure reducing valve is broken, and the spool moves, and the opening of the pressure reducing valve port is changed by the movement of the spool of the differential pressure reducing valve. Perform pressure compensation to move the spool of the differential pressure reducing valve to a new equilibrium position to work stably, and ensure that the pressure difference between the front and back of the orifice is basically unchanged. After considering the balance measures of hydraulic power in structure, it can be considered that the hydraulic force acting on the spool of differential pressure reducing valve is zero. Therefore, the pressure before and after the orifice acts on the two ends of the fixed difference pressure reducing valve spool to generate hydraulic thrust equal to the elastic force of the spring, so the pressure difference between the two ends of the fixed difference pressure reducing valve spool is equal to the elastic force of the spring divided by The effective area of the differential pressure reducing valve spool. Although the effective area of the spool of the differential pressure reducing valve is a certain value, the elastic force of the spring acting on the spool of the differential pressure reducing valve is not constant, and its elastic force is related to the compression of the spring, while the spring The amount of compression will vary with the position of the differential pressure reducing valve spool. Therefore, the pressure difference at both ends of the fixed differential pressure reducing valve core will also change, that is, the pressure difference before and after the orifice will change. Although structurally it can be considered to use a soft spring to reduce the change of elastic force caused by the displacement of the spool, it cannot guarantee the stability of the pressure difference between the front and rear of the orifice. In the same way, the known overflow throttle valve cannot ensure that the pressure difference between the front and rear of the throttle port is stable. Therefore, in the case where the speed control accuracy is particularly high, the performance of the existing speed control valve and overflow throttle valve cannot meet the requirements, so it is particularly important to design a new speed control valve whose flow rate is completely unaffected by load changes. important.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the existing speed control valve technology, and provide a new type of speed control valve, which is used in the meter-in speed control circuit and the bypass throttle speed control circuit, and the flow rate controlled by it is completely different. Affected by load changes to ensure that the hydraulic cylinder speed is stable.

In order to solve the above technical problems, the present invention adopts the following technical scheme: the new speed regulating valve is based on the existing speed regulating valve, and a reset plunger for resetting the valve core is arranged on the large end of the pressure reducing valve core to replace The original return spring, and the pressure oil P1 at the oil inlet of the speed regulating valve is led to the end chamber of the reset plunger through the oil hole 2, so that the spool of the pressure reducing valve is always subjected to a hydraulic force, even if the pressure reducing valve When the position of the spool changes due to feedback, the thrust P1×B generated by the hydraulic oil P1 acting on the end of the reset plunger remains unchanged, and B is the cross-sectional area of the end of the reset plunger. At the same time, an area compensation plunger is set at the small end of the pressure reducing valve spool. The cross-sectional area of the area compensation plunger is equal to that of the reset plunger, and the chamber at the end of the area compensation plunger passes through the oil discharge channel. Connected to fuel tank.

The above-mentioned reset plunger is set on the large end surface of the pressure reducing valve spool, the large end chamber of the pressure reducing valve spool communicates with the oil outlet of the speed regulating valve, and the end chamber of the reset plunger communicates with the speed regulating valve through oil hole 2. The oil inlet port of the valve is connected.

The above-mentioned area compensation plunger is set on the small end of the pressure reducing valve spool, and the cross-sectional area of the area compensation plunger is equal to that of the reset plunger, so as to ensure that the pressure oil P2 and P3 at both ends of the pressure reducing valve spool The area of effect is equal.

The chamber at the end of the area compensation plunger communicates with the oil tank through an oil drain passage.

Compared with the prior art, the present invention has the following advantages: since the original structure adopts spring reset, the position of the spool of the pressure relief valve changes when the pressure feedback is performed, resulting in a change in the elastic force of the return spring, so the pressure relief valve The differential pressure across the spool also changes. After adopting the new speed regulating valve structure of the present invention, it overcomes the inherent defect of using the spring to reset, so that a constant hydraulic thrust is always applied to the reset plunger at the end of the pressure reducing valve core, even if the pressure reducing valve core is operating. If the position changes during pressure feedback, it can also ensure that the hydraulic thrust at the end of the reset plunger remains unchanged, so as to ensure that the pressure difference between the front and rear of the orifice remains unchanged. When the opening of the orifice is constant, the flow through the speed regulating valve The flow rate is completely unaffected by load changes, thus ensuring the speed control accuracy of the hydraulic cylinder.

Description of drawings

Accompanying drawing is the working principle diagram of structure of the present invention.

The labels show: 1-valve body, 2-oil hole 1, 3-acting area A1 of the large end of the pressure reducing valve spool, 4-reset plunger end chamber, 5-reset plunger end cross-sectional area B , 6-Oil hole 2, 7-Reset plunger, 8-Reducing valve spool big end chamber, 9-Reducing valve spool, 10-Reducing valve spool small end effective area A2, 11-Reducing Pressure valve spool small end chamber, 12- speed control valve oil inlet, 13- pressure reducing valve spool small end effective area A3, 14- oil unloading channel, 15- area compensation plunger, 16- area Compensation plunger end chamber, 17-reducing valve spool small end end chamber, 18-oil hole three, 19-throttle valve adjusting screw, 20-throttle valve spool, 21-oil hole four, 22-speed valve oil outlet, 23-throttle valve spring, h1-relief valve port opening, h2-throttle valve port opening, P1-speed control valve oil inlet pressure, P2-decompression After the valve port is decompressed, the oil pressure, P3-speed valve oil outlet pressure.

detailed description

The technical scheme of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in the accompanying drawings, the new speed regulating valve includes a differential pressure reducing valve and a throttle valve, which are connected in series, with the differential pressure reducing valve at the front and the throttle valve at the rear. The large end of the pressure reducing valve spool 9 is provided with a reset plunger 7, and the end of the reset plunger 7 has a reset plunger end chamber 4, the effective area of which is B, and the pressure oil P1 output by the hydraulic pump is overflowed. After the valve is stabilized, it flows into the oil inlet 12 of the new speed regulating valve. The pressure oil P1 is divided into two paths at the entrance, one path is led to the end chamber 4 of the reset plunger through the oil hole 2 6, and acts on the area B of the end of the reset plunger 7; the other path passes through the decompression chamber with an opening degree of h1 After the valve port is decompressed, the pressure drops to P2, and P2 flows out after passing through the throttle valve port, and the pressure drops to P3, and P3 is connected to the hydraulic cylinder to drive the load. At the same time, the pressure oil P2 is led to the small end chamber 17 of the pressure reducing valve spool and the small end chamber 11 of the pressure reducing valve spool through oil hole 3 18 and oil hole 4 21 respectively. The effective area of action is A3, the effective area of the small end of the pressure reducing valve spool is A2, the pressure oil P3 is introduced to the large end area of action of the pressure reducing valve spool through oil hole 12, and the force of the pressure reducing valve spool is balanced The equation is:

P3×A1+P1×B=P2(A2+A3)+Fs

Fs is the hydraulic force on the relief valve spool;

From A1=A2+A3, arrange the above formula to get:

P2-P3=(P1×B-Fs)/A1

P2-P3 is the pressure difference between the front and back of the orifice. If the hydrodynamic balance measures are adopted in the structure, Fs=0, so:

P2-P3=(P1×B)/A1. Since the pressure oil P1 is adjusted to a fixed value by the relief valve at the outlet of the hydraulic pump, the areas B and A1 are constant, so P2-P3 is completely determined by (P1×B)/A1 to a certain value. The opening degree h2 of the orifice is also unchanged, so the flow rate flowing through the orifice is also a certain value, which ensures that the speed of the hydraulic cylinder remains constant.

The specific compensation process of the pressure reducing valve spool is described below in three load situations:

The first type: when the opening degree h2 of the throttle port is constant and the load is constant, the pressure P3 of the oil outlet 22 of the speed control valve remains unchanged, and the pressure P1 of the oil inlet port of the speed control valve is adjusted by the relief valve at the pump outlet to When the fixed value remains unchanged, when the opening degree h1 of the pressure reducing valve spool 9 is automatically adjusted to satisfy the pressure and flow balance equation, the pressure reducing valve spool 9 works stably in a balanced position, and at this time P2 is also stable, so according to the valve core The force balance equation is P2-P3=(P1×B-Fs)/A1, and Fs=0 after adopting hydrodynamic balance measures, so P2-P3=(P1×B)/A1. Since the opening degree h2 of the orifice remains unchanged at this time, the pressure difference P2-P3 before and after the orifice also remains unchanged, so the flow rate flowing through the orifice remains unchanged, and the guaranteed hydraulic cylinder speed remains unchanged.

The second type: On the basis of the first case (that is, the force balance of the spool at a certain position), if the load increases at this time, the pressure of P3 will increase, and the increase of P3 will break the spool 9 of the pressure reducing valve. The original force balance, the valve core 9 of the pressure reducing valve moves to the direction of increasing the valve port, the opening degree h1 of the valve port of the pressure reducing valve increases, and its decompression effect weakens, resulting in an increase of P2. When P2 increases to meet the requirements of P2- When P3=(P1×B)/A1, the spool 9 of the pressure reducing valve reaches the force balance in a new position and works stably again. At this time, P2-P3=(P1×B)/A1 is exactly the same as the first situation Similarly, when the guaranteed load increases, the pressure difference between the front and rear of the orifice remains constant. At this time, if the opening degree h2 of the orifice remains unchanged, the flow through the orifice remains unchanged, ensuring the hydraulic cylinder speed. It remains stable when the load increases.

The third type: similarly, on the basis of the first case (that is, the force balance of the spool at a certain position), if the load decreases at this time, the pressure of P3 will decrease, and the pressure reducing valve spool will be broken due to the decrease of P3. 9 In the original force balance, the valve core 9 of the pressure reducing valve moves to the direction of reducing the opening, the opening degree h1 of the valve port of the pressure reducing valve decreases, and its decompression effect increases, resulting in a decrease in P2. When P2 decreases to meet P2- When P3=(P1×B)/A1, the pressure reducing valve spool 9 reaches a force balance in a new position and works stably again. At this time, P2-P3=(P1×B)/A1 is the same as the first and second The two situations are exactly the same, which ensures that when the load decreases, the pressure difference between the front and rear of the orifice remains constant. At this time, if the opening degree h2 of the orifice remains unchanged, the flow through the orifice remains unchanged, ensuring hydraulic pressure. Cylinder speed remains constant as load decreases.

To sum up, no matter how the load changes, the new speed control valve can ensure that the pressure difference between the front and rear of the throttle port remains unchanged. After the throttle port opening degree h2 is adjusted, the flow rate through the throttle port remains unchanged, ensuring The stability of the hydraulic cylinder speed is constant.

Claims (3)

1. A new type of speed control valve, including a fixed differential pressure reducing valve and a throttle valve connected in series, is characterized in that: a reset plunger is set on the large end surface of the pressure reducing valve spool, and the end chamber of the reset plunger passes through Oil hole two communicates with the oil inlet of the speed regulating valve. 2. The new speed regulating valve according to claim 1, characterized in that: the small end of the valve core of the pressure reducing valve is provided with an area compensation plunger, and the cross-sectional area of the area compensation plunger is equal to the cross-sectional area of the reset plunger. equal. 3. The novel speed control valve according to claim 2, characterized in that the chamber at the end of the area compensation plunger communicates with the oil tank through an oil drain passage.