CN220769834U - Control valve and engineering machinery hydraulic system - Google Patents

Abstract

A control valve includes a valve body defining a valve chamber and formed with at least an oil inlet, an oil return, and a working oil port; and a spool mounted in the valve chamber and axially slidable to define at least a closed position of the control valve and a working position communicating the oil inlet port with the working oil port. The valve core is provided with a pressure relief channel, and the pressure relief channel is arranged to realize communication between the working oil port and the oil return port in at least one stroke of the valve core, which is switched between the working valve position and the closing valve position. A work machine hydraulic system includes the control valve disposed between a hydraulic pump and a hydraulic actuator. The control valve is capable of providing a brake oscillation suppression function.

Description

Control valve and engineering machinery hydraulic system

Technical Field

The present application relates to a control valve for use in a hydraulic system and a hydraulic system for a construction machine employing such a hydraulic valve.

Background

Control valves are often used in hydraulic systems of work machines to control the supply of hydraulic oil to an implement. When the actuator is braked by switching the valve position of the control valve, if the weight driven by the actuator is large, the actuator may swing at the braking position. For example, many work machines include a lower carriage and an upper carriage that is rotatable relative to the lower carriage by a swing motor drive. An operator controls the action of the rotary motor through the rotary handle. When the swing motor needs to be stopped, the operator pushes the swing handle back to the neutral position. Based on the return signal of the rotary handle, the controller switches the valve position of the control valve of the rotary motor, so that the oil supply pipeline and the oil return pipeline of the rotary motor are cut off. However, the boarding cannot stop immediately but will continue to slip under inertia, resulting in an increase in pressure in the return line and a decrease in pressure in the supply line, possibly even cavitation. In the event of such a pressure change, the swing motor again tends to rotate in the opposite direction, thereby swinging back and forth at the braking position. In order to avoid the problem in the prior art, an anti-reverse (anti-swing) valve is generally adopted in a hydraulic loop, and when the rotary motor is braked, high-pressure oil in an oil return pipeline flows into an oil supply pipeline through the anti-swing valve to compensate the oil pressure in the oil supply pipeline, so that the oil pressure on two sides of the rotary motor tends to be stable, and the rotary motor is prevented from reversing.

However, adding an anti-roll valve to the hydraulic system can result in increased costs.

Disclosure of Invention

It is an object of the present application to provide an improved control valve which overcomes the problems associated with brake hunting in the prior art.

To this end, the present application provides in one aspect thereof a control valve comprising:

a valve body defining a valve chamber and formed with at least an oil inlet, an oil return, and a working oil port; and

a spool mounted in the valve chamber and axially slidable to define at least a closed position of the control valve and a working position communicating the oil inlet port with the working oil port;

the valve core is provided with a pressure relief channel, and the pressure relief channel is arranged to realize communication between the working oil port and the oil return port in at least one stroke of the valve core, which is switched between the working valve position and the closing valve position.

In one embodiment, the pressure relief channel has a first end and a second end disposed at axially different locations; in the closed valve position, the second end is communicated with the oil return port, and the valve body breaks the gap between the first end and the working oil port; in the working valve position, the first end is communicated with the working oil port, and the second end is communicated with the oil return port, or the valve body breaks the gap between the second end and the oil return port.

In one embodiment, the axial positions of the first and second ends of the relief passage are designed such that, in the course of the valve element from the working valve position to the closing valve position:

after the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port;

or when the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port;

or before the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port.

In one embodiment, the relief passage includes one or more throttle grooves formed on an outer peripheral surface of the spool that extend parallel to an axial direction.

In one embodiment, the pressure relief passage includes radial holes formed in the valve spool at different axial locations and axial holes connecting the radial holes.

In one embodiment, the relief passage includes a beveled aperture in the valve spool extending between different axial end positions.

In one embodiment, the axial position of the spool is controlled by a valve position control energy input from a control end of the control valve, the value of the valve position control energy being set in association with a preset spool movement speed during at least a portion of the spool movement from the operating valve position to the closed valve position.

In one embodiment, the number of the working oil ports is two, and the control valve is provided with a corresponding working valve position for communicating the oil inlet with one of the two working oil ports; and is also provided with

And a corresponding pressure relief channel is arranged in the valve core for each working oil port, and each pressure relief channel is arranged to realize communication between the corresponding working oil port and the oil return port in at least one stroke of the valve core switched between the corresponding working valve position and the closed valve position.

The present application provides, in another aspect thereof, a hydraulic system for a construction machine, comprising:

a hydraulic pump;

a hydraulic actuator; and

the control valve is arranged between the hydraulic pump and the hydraulic actuator to control the hydraulic pump to supply hydraulic oil to the hydraulic actuator.

In the hydraulic system of the construction machine, the hydraulic actuator may be an entry swing motor of the construction machine.

The case of this application control valve is formed with the pressure release passageway for establish the intercommunication between the hydraulic fluid outlet and tend the work hydraulic fluid outlet that pressure risen when carrying out braking operation to actuating element through this control valve, with the high-pressure oil pressure release in this work hydraulic fluid outlet, make actuating element both sides oil pressure tend to stability fast, restrain actuating element's braking swing. Because the control valve of the present application provides a brake swing inhibiting function, the hydraulic system can eliminate the anti-reverse (anti-swing) valve often employed in the prior art, thereby reducing the cost and complexity of the hydraulic system.

Drawings

The foregoing and other aspects of the present application will be more fully understood and appreciated from the following detailed description taken with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a hydraulic system in which the control valve of the present application may be employed;

FIG. 2 is a schematic illustration of an exemplary configuration of a control valve of the present application;

FIG. 3 is a schematic illustration of a spool of the control valve shown in FIG. 2;

FIGS. 4-6 are schematic diagrams of two valve positions of the control valve shown in FIG. 2;

FIG. 7 is a schematic illustration of a valve position control scheme of the control valve shown in FIG. 2;

fig. 8-10 are schematic diagrams of other exemplary configurations of control valves of the present application.

Detailed Description

The present application relates generally to control valves for hydraulic systems for controlling the supply of hydraulic oil to actuators. An example of a hydraulic system using the control valve of the present application is a hydraulic system of a construction machine, wherein an example of an actuator controlled by the control valve is a swing motor. However, the control valve of the present application may also be used to control the supply of hydraulic oil to various forms of actuators in other various hydraulic systems.

Referring to an example of a hydraulic system to which the present application is applied, which is shown in fig. 1, a hydraulic pump Pu in the hydraulic system controls the operation of a hydraulic motor (e.g., a boarding swing motor of a construction machine) Mo through a control valve V. In this example, the control valve V is a three-position four-way valve, and has four oil ports, namely an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, which are hereinafter referred to as P, T, a, and B. The port P is connected with the output end of the hydraulic pump Pu, the port T is connected with an oil tank, and the port A and the port B are respectively connected with two oil ports Am and Bm of the hydraulic motor Mo.

The control valve V has three positions, namely a neutral (or closed) position, a first operating position and a second operating position. In the middle position, each oil port is cut off. In the first working valve position, the port P is communicated with the port A, and the port T is communicated with the port B. In the second working valve position, the port P is communicated with the port B, and the port T is communicated with the port A. In the neutral position of the control valve V, the hydraulic pump Pu cuts off the supply of hydraulic oil to the hydraulic motor Mo, and the hydraulic motor Mo stops rotating. In the first and second operating positions of the control valve V, the hydraulic pump Pu supplies hydraulic oil to the hydraulic motor Mo in different directions, so that the hydraulic motor Mo rotates in different directions.

One possible configuration of the control valve V of fig. 1 is shown in fig. 2, with the control valve V in a neutral position. The control valve V mainly includes a valve body 1 defining a valve chamber, and a spool 2 mounted in the valve chamber and axially slidable to effect switching of the valve position. Only the portion of the control valve V relevant to the present application is shown in fig. 2, and the other portions are not shown.

Oil grooves (undercut grooves) T1, a1, p1, b1, T2 are formed in the valve body 1 in this order from left to right facing the valve chamber, wherein the oil grooves a1, p1, b1 communicate with the oil port A, P, B, respectively, and the oil grooves T1, T2 communicate with the oil port T through an internal oil passage in the valve body 1.

Referring to fig. 2, oil grooves (undercut grooves) a2, b2 are formed in the outer periphery of the valve body 2, and the oil groove a2 is located on the left side of the oil groove b2. The oil grooves a2 and b2 divide the body of the valve element 2 from left to right into a first valve element segment 21, a second valve element segment 22 and a third valve element segment 23. The outer periphery of the first spool section 21 is formed with one or more relief passages (throttle grooves) 24 extending parallel to the spool axial direction. The pressure relief passage 24 has a first end (right end) axially adjacent to the oil groove a2 but spaced from the oil groove a2 and a second end (left end) axially distant from the oil groove a2.

Returning to fig. 2, in the neutral position of the control valve V, the oil groove a1 faces the oil groove a2, and the oil groove b1 faces the oil groove b2. The first spool section 21 blocks the oil groove t1 from the oil groove a1, the second spool section 22 blocks the oil groove p1 from both the oil grooves a1 and b1, and the third spool section 23 blocks the oil groove b1 from the oil groove t 2. Thus, the ports P, T, a, and B are all blocked, and the control valve V is closed. In addition, a portion of the relief passage 24 faces the oil groove t1, and the relief passage 24 does not communicate with any other oil groove in the valve body 1.

Fig. 4 shows the spool 2 sliding to the right in the valve chamber so that the control valve V reaches the first working position. In this position, oil groove a2 establishes communication between oil groove a1 and oil groove p1, oil groove b2 establishes communication between oil groove b1 and oil groove t2, and second spool segment 22 interrupts oil groove p1 from oil groove b 1. Thus, the port P is communicated with the port A, the port T is communicated with the port B, and the control valve V is in a full-open state. At this time, the first end of the relief passage 24 faces the oil groove a1, and the second end of the relief passage 24 is closed by the valve body 1.

In the process of switching the control valve V from the first operating valve position to the neutral position, the valve spool 2 moves leftward, and after the opening of the control valve V reaches a certain preset opening, the second end of the relief passage 24 reaches a state facing the oil groove t1, so that the relief passage 24 establishes communication between the oil groove a1 and the oil groove t1, and meanwhile, the oil grooves a1 and p1 remain in communication, but the opening of the control valve V gradually decreases. This state is shown in fig. 5.

As the spool 2 moves further to the left, the opening degree of the control valve V continues to decrease until it decreases to zero, while the relief passage 24 maintains communication between the oil groove a1 and the oil groove t 1. This state is shown in fig. 6.

Thereafter, the valve body 2 moves further leftward, and the first end of the relief passage 24 is separated from the oil groove a1, and is closed by the valve body material between the oil groove a1 and the oil groove t1, and the space between the oil groove a1 and the oil groove t1 is interrupted. Finally, the control valve V is switched to the neutral position shown in fig. 2.

During the switching from the first operating valve position to the neutral position, in a state in which the relief passage 24 causes communication between the oil groove a1 and the oil groove T1, high-pressure hydraulic oil in the oil groove a1 (i.e., the oil port a) flows to the oil groove T1 (i.e., the oil port T) through the relief passage 24, so that the rapid relief of the oil port a is realized, the oil pressure on both sides of the hydraulic motor Mo or other forms of hydraulic actuators controlled by the control valve V quickly becomes stable, and the braking oscillation of the hydraulic motor Mo or other forms of actuators is suppressed. Thus, the brake hunting suppressing function is provided in the control valve V without the need for the prior art anti-reverse (anti-hunting) valve in the hydraulic system.

In order to enhance the pressure release capability of the pressure release passage 24, on the one hand, it is considered to appropriately increase the flow area of the pressure release passage 24, and on the other hand, it is considered to appropriately lengthen the time for which communication between the oil tank a1 and the oil tank t1 is maintained through the pressure release passage 24 during the switching of the control valve V from the first operating valve position to the neutral position. The valve position of the control valve V can be switched electrically, hydraulically or the like. If an electric switching mode is adopted, valve position control energy input by a control end of the control valve V is characterized as current of an electromagnetic coil; if a hydraulic switching mode is adopted, valve position control energy input by a control end of the control valve V is characterized as pilot pressure. Whichever valve position control energy is adopted, the moving speed of the spool 2 can be appropriately reduced by controlling the valve position control energy after the relief passage 24 initially establishes communication between the oil tank a1 and the oil tank t1, thereby extending the time for which communication between the oil tank a1 and the oil tank t1 is maintained through the relief passage 24.

For example, one valve position control energy scheme is shown in FIG. 7. In fig. 7, the horizontal axis represents time, and the vertical axis represents valve position control energy. As schematically represented by the graph in fig. 7, the valve position control energy applied to the respective control end of the control valve V is rapidly increased from the minimum value Smin at a time point t1, reaches a maximum value Smax at a time point t2 immediately after the time point t1, and thereafter maintains the maximum value Smax of the valve position control energy until a later braking time point t3. From the braking time point t3, the valve position control energy at the control end is rapidly reduced until a time point t4 at which the relief passage 24 initially establishes communication between the oil tank a1 and the oil tank t 1. At time t4, valve position control energy value S1> minimum value Smin. After time t4, the valve position control energy is reduced at a set valve position control energy reduction rate (which is smaller than the valve position control energy reduction rate in the period between time t3 and time t 4) until time t5, the valve position control energy is reduced to the minimum value Smin. The time point t5 is a time point when the control valve V initially reaches the neutral position, or a time point when the communication between the oil grooves a1 and t1 is initially disconnected. After time t5, the valve position control energy remains at a minimum value Smin.

Other ways of controlling valve position control energy during communication between tank a1 and tank t1 via relief passage 24 are also contemplated.

As regards the structure of the relief passage 24, other forms of relief passage 24 may be employed in addition to the one or more grooves formed on the outer periphery of the first spool section 21 extending in the spool axial direction as described above.

For example, in the example of the valve spool 2 shown in fig. 8, the relief passage 24 includes radial holes that are opened at different axial positions (axial positions where the first end and the second end of the relief passage 24 are located) and axial holes that connect the radial holes. At each axial location, one or more radial holes may be provided that extend radially to the axial hole.

In the example of the valve cartridge 2 shown in fig. 9, the relief passage 24 includes one or more angled holes extending between the first and second ends. If there are a plurality of inclined holes, these are communicated at their central portions.

In the previously described example, the relief passage 24 is designed such that, in the fully opened state of the control valve V, the first end of the relief passage 24 faces the oil groove a1 and the second end of the relief passage 24 is closed by the valve body 1. However, it is also possible to design the relief passage 24 such that in the fully opened state of the control valve V, the first end of the relief passage 24 faces the oil sump a1 and the second end of the relief passage 24 faces the oil sump T1, i.e. in the fully opened state of the control valve V, the relief passage 24 establishes communication between the a port and the T port of the control valve. In such a control valve V, the valve position control energy reduction may be controlled at a set smaller valve position control energy reduction rate throughout or during a portion of the time period during the switching from the valve full open position to the closed position to extend the time for which communication between the oil tank a1 and the oil tank t1 is maintained through the relief passage 24.

Further, in the example described above, during the switching of the control valve V from the first operating valve position to the neutral position, the communication between the oil tanks a1 and p1 is disconnected after the pressure relief passage 24 establishes communication between the oil tank a1 and the oil tank t 1. However, the pressure relief channel 24 may also be designed to: during the switching of the control valve V from the first operating valve position to the neutral position, the communication between the oil grooves a1 and p1 is interrupted before the pressure relief passage 24 establishes communication between the oil groove a1 and the oil groove t1, or the communication between the oil grooves a1 and p1 is interrupted while the pressure relief passage 24 establishes communication between the oil groove a1 and the oil groove t 1. Obviously, the timing problem between the point in time when communication between the oil grooves a1 and t1 and the point in time when communication between the oil grooves a1 and p1 is disconnected can be achieved by designing the axial positions of the relevant oil grooves and the axial positions of the first and second ends of the relief passage 24, depending on the specific application requirements. The length of time that the oil sump a1 is in communication with the oil sump t1 is achieved by setting the valve position control energy value.

Further, in the example described above, the relief passage 24 is provided for one of the working ports (port a) of the control valve V. In the example shown in fig. 10, the corresponding relief passages 24 are provided for both of the working ports (ports a, B) of the control valve. The relief passage 24 provided for the B port has the same or similar structure and brake hunting suppression function as the relief passage 24 provided for the a port described above.

When the hydraulic motor Mo is a loading rotary motor of the engineering machinery, the pressure release channels 24 are arranged for the two working oil ports of the control valve V, so that the loading rotary motor has a swing inhibiting function during forward and reverse rotation braking.

Furthermore, in the example described above, the control valve V is a three-position four-way valve, however, the spool with the relief passage 24 of the present application may be applied to control valves having other numbers of valve positions and other numbers of ports.

Although the present application is described herein with reference to specific exemplary embodiments, the scope of the application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the present application.

Claims (10)

1. A control valve, comprising:

a valve body (1) defining a valve chamber and formed with at least an oil inlet (P), an oil return (T), a working oil port; and

a spool (2) mounted in the valve chamber and axially slidable to define at least a closed position of the control valve and a working position communicating the oil inlet with the working oil port;

the valve is characterized in that the valve core is provided with a pressure relief channel (24), and the pressure relief channel is arranged to realize communication between the working oil port and the oil return port in at least one stroke of the valve core switched between the working valve position and the closing valve position.

2. The control valve of claim 1, wherein the pressure relief passage has a first end and a second end disposed at axially different locations; in the closed valve position, the second end is communicated with the oil return port, and the valve body breaks the gap between the first end and the working oil port; in the working valve position, the first end is communicated with the working oil port, and the second end is communicated with the oil return port, or the valve body breaks the gap between the second end and the oil return port.

3. The control valve of claim 2, wherein the axial positions of the first and second ends of the relief passage are designed such that, in the travel of the spool from the working valve position to the closed valve position:

after the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port;

or when the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port;

or before the oil inlet is disconnected from the working oil port, the pressure relief channel is communicated between the working oil port and the oil return port.

4. The control valve of any of claims 1-3, wherein the relief passage includes one or more throttle grooves formed on an outer peripheral surface of the spool that extend parallel to the axial direction.

5. A control valve according to any one of claims 1 to 3, wherein the pressure relief passage comprises radial bores provided in the valve spool at different axial positions and an axial bore connecting the radial bores.

6. A control valve according to any of claims 1-3, wherein the relief passage comprises a chamfer extending in the spool between different axial end positions.

7. A control valve according to any one of claims 1-3, characterized in that the axial position of the spool is controlled by valve position control energy input from the control end of the control valve, the value of the valve position control energy being set in connection with a preset spool movement speed during at least a part of the time period during which the spool is moved from the working valve to the closing valve position.

8. A control valve according to any one of claims 1-3, wherein the number of said working ports is two, said control valve having a respective working valve position communicating said oil inlet with one of the two working ports; and is also provided with

And a corresponding pressure relief channel is arranged in the valve core for each working oil port, and each pressure relief channel is arranged to realize communication between the corresponding working oil port and the oil return port in at least one stroke of the valve core switched between the corresponding working valve position and the closed valve position.

9. A hydraulic system of a work machine, comprising:

a hydraulic pump;

a hydraulic actuator; and

a control valve disposed between the hydraulic pump and the hydraulic actuator to control the hydraulic pump to supply hydraulic oil to the hydraulic actuator;

the control valve according to any one of claims 1 to 8.

10. The work machine hydraulic system of claim 9, wherein the hydraulic actuator is an on-board swing motor.