WO2013063997A1

WO2013063997A1 - Hydraulic control loop

Info

Publication number: WO2013063997A1
Application number: PCT/CN2012/082285
Authority: WO
Inventors: 左春庚; 李美香; 张劲; 魏星
Original assignee: 中联重科股份有限公司; 湖南中联重科专用车有限责任公司
Priority date: 2011-10-31
Filing date: 2012-09-28
Publication date: 2013-05-10
Also published as: CN102374203B; CN102374203A

Abstract

A hydraulic control loop comprises a direction control valve (10) having a bypass throttle loop and an execution element (20) connected to the direction control valve. The hydraulic control loop further comprises a valve (30). The valve (30) is connected in the bypass throttle loop in series, so that when the execution element (20) is started, a flow of hydraulic oil in the bypass throttle loop is equal to a system flow supplied to the direction control valve (10). When the execution element (20) is started, the valve (30) controls the hydraulic oil in the bypass throttle loop, so that the flow of hydraulic oil in the bypass throttle loop is equal to the system flow supplied to the direction control valve (10), that is to say, the system flow supplied to the direction control valve (10) completely flows into an oil box through the bypass throttle loop, so no hydraulic oil flows to the execution element (20), so that when the execution element (20) is started, the flow of hydraulic oil entering the execution element (20) starts from zero.

Description

Hydraulic control circuit

Technical field

The present invention relates to the field of hydraulic control and, in particular, to a hydraulic control circuit having a bypass throttle circuit. Background technique

In hydraulic drive systems, a speed control loop is usually also provided to meet the control requirements for the speed of movement of the actuator. At present, there are various ways to control the movement speed of the actuator: for example, by changing the flow cross section of the flow control valve to control and regulate the flow into or out of the actuator, thereby realizing the throttle speed regulation loop of the speed regulation; A variable speed control loop that achieves speed regulation by changing the displacement of a hydraulic pump or a hydraulic motor. Since variable-pressure hydraulic pumps are usually required for volumetric speed-regulating circuits, the cost is increased. Therefore, more throttling speed-regulating circuits are used, such as bypass throttle circuits using throttle valves or commutation Valve reversing valve speed control loop.

For example, Figure 1 shows a conventional hydraulic control circuit. As shown in FIG. 1, the hydraulic control circuit includes a directional control valve 10 and an actuator 20 (such as a hydraulic motor) connected to the directional control valve 10, the directional control valve 10 including a bypass inlet P' and a bypass outlet. a bypass throttle circuit of C, wherein the bypass inlet P' communicates with the oil inlet port P (ie, the working hydraulic oil of the hydraulic pump is supplied to the oil inlet port P and the bypass inlet port P' of the directional control valve 10), bypassing The outlet C communicates with the fuel tank, and the flow passage section of the bypass throttle circuit changes with the opening degree of the directional control valve 10. Among them, 11-16 denote the respective throttle grooves at the respective ends of the spool of the directional control valve 10.

Figure 1 shows the working state of the hydraulic control circuit when the directional control valve 10 is in the neutral position. In this state, the working oil ports (A port and B port) of the directional control valve 10, the oil inlet port P and the back are shown. The oil ports T are all closed, and the bypass inlet P' and the bypass outlet C are connected, and the bypass throttle circuit (substantially) does not throttle the flow of oil flowing through the bypass inlet P' and the bypass outlet C. At this time, execute Element 20 does not operate and hydraulic oil from a hydraulic pump (not shown) flows back to the tank through bypass inlet P' and bypass outlet C.

For example, when the directional control valve 10 moves from the neutral position to the left position shown in FIG. 1, the opening degree of the directional control valve 10 gradually increases, the oil inlet port P communicates with the A port, and the B port communicates with the oil return port T. At the same time, the through-flow section of the bypass throttle circuit formed by the bypass inlet P' and the bypass outlet C is gradually reduced. At this time, most of the hydraulic oil from the hydraulic pump sequentially flows through the oil inlet P, the oil inlet throttle groove 13, and the A port, passes through the actuator 20 and performs work on the actuator, and then returns oil from the port B. The throttle groove 11 and the oil return port T flow back to the oil tank. A small portion of the hydraulic oil from the hydraulic pump flows through the bypass inlet P', the bypass throttle 12, and the bypass outlet C to flow back to the tank after throttling.

The operating speed of the actuator 20 if the system flow is constant (if the actuator

20 is a hydraulic cylinder, the operating speed of the actuator 20 is the linear moving speed of the piston rod of the hydraulic cylinder; if the actuator 20 is a hydraulic motor, the operating speed of the actuator 20 is the rotational speed of the hydraulic motor. The system load and the opening of the directional control valve 10.

Specifically, when the load is constant, if the opening degree of the directional control valve 10 is increased, the flow cross section of the bypass throttle circuit formed by the bypass inlet P' and the bypass outlet C is reduced, and therefore, The flow rate of the hydraulic oil acting on the actuator 20 is increased, and the flow rate of the hydraulic oil flowing through the bypass throttle circuit is decreased, thereby accelerating the operating speed of the actuator 20; conversely, if the load is constant, if the direction is controlled When the opening degree of the valve 10 is decreased, the flow cross section of the bypass throttle circuit is increased, so that the flow rate of the hydraulic oil acting on the actuator 20 is decreased, and the flow rate of the hydraulic oil flowing through the bypass throttle circuit is increased. Large, thereby slowing the operating speed of the actuator 20. Through the above process, the speed control of the actuator 20 is achieved by the bypass throttle circuit of the directional control valve 10.

In the case of a certain degree of opening, if the system load increases, the pressure of the hydraulic oil of the system will increase, so that the flow rate of the hydraulic oil flowing through the bypass throttle circuit will increase, but the amount of oil supplied by the system It is certain that it will inevitably lead to a decrease in the flow rate of the hydraulic oil acting on the actuator 20, thereby slowing down the operating speed of the actuator 20; conversely, if the system load is reduced, the pressure of the system hydraulic oil is lowered. Thereby reducing the flow rate of the hydraulic oil flowing through the bypass throttle circuit, Therefore, the flow rate of the hydraulic oil acting on the actuator 20 is inevitably increased, thereby accelerating the running speed of the actuator 20.

From the above analysis, it is known that the main factor affecting the operating speed of the actuator 20 is the opening degree of the system load and the directional control valve 10, in other words, the main influencing factor of the flow rate of the hydraulic oil acting on the actuator 20 is the system load and direction. The opening of the control valve 10 is controlled.

Therefore, such a hydraulic control circuit has the following drawbacks.

When the system is in the idle state, the spool of the directional control valve 10 is in the neutral position, and the system hydraulic oil flows back to the oil tank through the bypass circuit. Since the throttle groove is designed according to the idle speed, the hydraulic oil in the bypass circuit is The flow rate is equal to the system flow (ie, the oil flow capacity of the bypass return is equal to the system oil supply).

However, when the actuator 20 is actuated (at this time, the spool of the directional control valve 10 just starts to move), the excess hydraulic oil is caused by the rapid increase of the system flow rate, thereby causing the bypass circuit to have less oil flow than the system oil supply. The flow will flow to the actuator 20, causing a sudden increase in the flow of hydraulic oil entering the actuator 20 (i.e., when the actuator 20 is actuated, the flow of hydraulic oil entering the actuator 20 is not zero-based).

Due to the presence of such defects, the actuator 20 is subject to severe jitter at startup. Therefore, the conventional hydraulic control circuit has the drawback that the stability of the actuator is poor at startup. How to improve the smooth running of the traditional hydraulic control circuit at startup is a technical problem to be solved. Summary of the invention

It is an object of the present invention to provide a hydraulic control circuit with which a better operational stability can be achieved at startup.

In order to achieve the above object, the present invention provides a hydraulic control circuit including a directional control valve having a bypass throttle circuit and an actuator coupled to the directional control valve, the hydraulic control circuit further including a valve, a valve is connected in series in the bypass throttle circuit to enable The flow rate of hydraulic oil flowing through the bypass throttle circuit can be equal to the system flow supplied to the directional control valve when the actuator is activated.

Preferably, the valve is capable of maintaining a constant flow rate of hydraulic oil flowing through the actuator when the system flow rate supplied to the directional control valve is constant.

Preferably, when the load on the actuator is increased, the valve correspondingly reduces the flow cross section of the valve port of the valve; when the load on the actuator is reduced, the valve correspondingly The flow cross section of the valve port of the valve is increased such that the flow rate of the hydraulic oil flowing through the bypass throttle circuit does not change if the directional control valve has a constant opening.

Preferably, the hydraulic control circuit further includes a fuel tank, the valve is a hydraulic flow control valve including an inlet, an outlet, and a first control port and a second control port, the inlet and the direction control of the pilot flow control valve a bypass outlet of the valve is communicated, an outlet of the pilot flow control valve is in communication with the oil tank, and a first control port of the pilot flow control valve is directly or indirectly connected to a system pressure of the hydraulic control circuit, The second control port is in communication with the bypass throttle circuit and is connected to a hydraulic control device acting on the spool of the pilot flow control valve.

Preferably, the first control port of the pilot flow control valve is in direct communication with the oil inlet of the directional control valve.

Preferably, the hydraulic control device comprises a throttle valve and a flow-sensitive piston cylinder, the throttle valve being connected in series in an oil inlet path of the directional control valve, the flow-sensitive piston cylinder comprising a closed piston cylinder and an axially axial direction a piston reciprocally disposed in the cylinder, the piston being coupled to a first piston rod extending from a first end wall of the cylinder, the first piston rod and a spool of the pilot flow control valve a spring connection, a first cavity is defined between the piston and the first end wall, and a second cavity is defined between the piston and the second end wall, the first cavity and the directional control valve The downstream portion of the throttle valve of the oil inlet passage is connected, and the second chamber is connected to the upstream portion of the throttle valve of the oil inlet passage of the directional control valve.

Preferably, the piston of the flow sensitive piston cylinder is further coupled with a second piston rod extending in a direction opposite to the first piston rod to a second end wall of the piston barrel. Preferably, the hydraulic control device comprises a controller and an electric control valve electrically connected to the controller, the output end of the electric control valve is connected to the second control port, thereby acting on the liquid control flow control valve a spool, the controller controlling a pressure of an output of the electronically controlled valve based on a flow signal of a system flow supplied to the directional control valve.

Preferably, the directional control valve has an oil inlet P, a return port T, and two working ports Α,

And a valve constituting the bypass inlet P' and the bypass outlet C of the bypass throttle circuit, and a bypass throttle groove 15 is disposed between the bypass inlet P' and the bypass outlet C, The oil inlet port and the bypass inlet P' are both in pressure communication with the system, and the working port ports Β, Β are respectively in communication with the actuator 11, and the bypass outlet C is in communication with the valve 30.

Preferably, the actuator is a hydraulic motor, and the hydraulic control circuit is a swing control loop. According to the above technical solution, when the actuator is started, that is, when the spool of the directional control valve starts to move from the neutral position to the left or right position, the system flow rate is increased, and the valve is used to control the hydraulic oil in the bypass throttle circuit, thereby The flow rate of the hydraulic oil flowing through the bypass throttle circuit can be equal to the system flow supplied to the directional control valve, that is, the system flow supplied to the directional control valve flows substantially all through the bypass throttle circuit to the fuel tank, thus No hydraulic oil flows to the actuator to achieve a zero flow of hydraulic oil entering the actuator when the actuator is activated. Further, it is possible to avoid violent jitter of the actuator and achieve the object of the present invention.

Other features and advantages of the invention will be described in detail in the detailed description which follows. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are in the In the drawing:

Figure 1 is a schematic view of a conventional hydraulic control circuit;

2 is a schematic view of a hydraulic control circuit in accordance with a preferred embodiment of the present invention; Figure 3 is a detailed schematic view showing the connection relationship between the liquid control flow control valve and the flow sensitive piston cylinder of Figure 1;

Figure 4 is a schematic view showing the structure of the flow sensitive piston rod of Figure 3;

Figure 5 is a schematic illustration of a hydraulic control circuit in accordance with another preferred embodiment of the present invention. detailed description

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are intended to be illustrative and not restrictive.

As shown in FIG. 2, the hydraulic control circuit according to the present invention includes a directional control valve 10 having a bypass throttle circuit and an actuator 20 coupled to the directional control valve 10, the hydraulic control circuit further including a valve 30, the valve 30 is connected in series in the bypass throttle circuit so that the flow rate of the hydraulic oil flowing through the bypass throttle circuit can be equal to that supplied to the directional control valve 10 when the actuator 20 is activated System traffic.

According to this technical solution, when the actuator 20 is started, that is, when the spool of the directional control valve 10 starts to move from the neutral position to the left or right position, the system flow rate Q is increased, and the valve 30 is used to bypass the hydraulic oil in the throttle circuit. Control so that the flow rate of hydraulic oil flowing through the bypass throttle circuit can be equal to the system flow supplied to the directional control valve 10, that is, the system flow supplied to the directional control valve 10 is substantially all bypass bypassed The circuit flows to the fuel tank so that no hydraulic oil flows to the actuator 20 to achieve a zero flow of hydraulic oil entering the actuator 20 when the actuator 20 is activated. Further, it is possible to avoid the violent jitter of the actuator 20, and the object of the present invention is achieved.

In order to achieve the object of the present invention, the valve 30 can have various forms as long as the flow passage area of the bypass throttle circuit can be adjusted and controlled when the actuator 20 is started, so that the hydraulic pressure oil flows into the system when the actuator 20 is started. The bypass throttle circuit can be used.

For example, the valve 30 can be a hydraulic flow control valve or an electronically controlled flow control valve, the electronically controlled flow control The valve or pilot flow control valve can act according to the signal of the system flow. Two preferred embodiments of the valve 30 will be described in detail below.

Preferably, the valve 30 is also capable of maintaining a constant flow rate of hydraulic oil flowing through the actuator 20 while the hydraulic control system is operating, in the event that the system flow rate supplied to the directional control valve 10 is constant. Therefore, in the case where the flow rate of the hydraulic oil supplied to the directional control valve by the hydraulic pump (i.e., the system flow rate) is constant, the hydraulic oil flowing through the actuator 20 can be utilized by the valve 30 regardless of the change in the load on the actuator. The traffic (basically) remains the same. Thus, the actuator can be maintained at a relatively stable operating speed during operation, thereby achieving a stable operating state.

Specifically, with the valve 30 connected in series in the bypass throttle circuit, when the load on the actuator 20 is increased, the valve 30 correspondingly reduces the flow cross section of the valve port of the valve; When the load on the actuator 20 is reduced, the valve 30 correspondingly increases the flow cross section of the valve port of the valve so that the directional control valve 10 has a constant opening degree, flowing through The flow rate (basic) of the hydraulic oil of the bypass throttle circuit does not change. This is because, for example, when the load on the actuator 20 is increased, the system pressure is increased, and an increase in the system pressure will push the spool of the valve 30 to decrease its flow area, so the pressure at the inlet of the valve 30 will rise. Until the spool of the valve 30 is forced to reach equilibrium again, the pressure difference between the oil supply port of the directional control valve 10 and the inlet of the valve 30 remains substantially unchanged, so that the flow rate of the hydraulic oil through the bypass outlet is substantially unchanged. Similarly, when the load on the actuator 20 is reduced, the system pressure is reduced and the reduction in system pressure will push the spool of the valve 30 to increase its flow area, so the inlet pressure of the valve 30 will drop until the valve The spool of 30 is again stressed by the force, so that the pressure difference between the oil supply port of the directional control valve 10 and the inlet of the valve 30 remains substantially unchanged, so that the flow rate of the hydraulic oil through the bypass outlet is substantially unchanged.

Therefore, regardless of the change in the system load, since the flow of the hydraulic oil flowing through the bypass throttle circuit remains substantially unchanged, and the system flow rate can be kept constant, the directional control valve is supplied thereto.

The flow rate of the hydraulic oil of 10 is substantially constant, passing through the working port of the directional control valve 10 (port A or Port B) the flow rate of the hydraulic oil acting on the actuator 20 (this flow rate is equal to the system flow rate Q of the hydraulic oil supplied to the directional control valve 10 minus the flow rate Q2 of the hydraulic oil flowing through the bypass throttle circuit) It remains unchanged, so that the oil flow rate for the actuator can be made independent of the load change, and only by the opening of the spool of the directional control valve 10 (i.e., the flow area of the bypass outlet).

The valve 30 capable of realizing the technical solution of the present invention can have various forms. For example, preferably, as shown in FIGS. 2 and 3, the hydraulic control circuit further includes a fuel tank, and the valve 30 is a hydraulic flow including an inlet 301, an outlet 302, and a first control port 303 and a second control port 304. a control valve, an inlet 301 of the pilot flow control valve is in communication with a bypass outlet C of the directional control valve 10, and an outlet 302 of the pilot flow control valve is in communication with the fuel tank, thereby causing the valve 30 to be connected in series In the fuel saving circuit. The first control port 303 of the pilot flow control valve is directly or indirectly connected to the system pressure of the hydraulic control circuit, thereby regulating the flow area of the valve 30, so that the oil flow rate of the actuator is independent of the load change. the goal of. Preferably, as shown in Figures 2 and 3, the first control port 303 of the pilot flow control valve is in direct communication with the oil inlet of the directional control valve 10.

Further, the second control port 304 is in communication with the bypass throttle circuit and is connected to a hydraulic control device serving as a spool of the pilot flow control valve. Therefore, the position of the spool of the pilot flow control valve is adaptively adjusted by the action of the spring, so that when the actuator 20 is started, the flow rate of the hydraulic oil entering the actuator 20 is zero. .

The hydraulic control device can have various forms, such as shown in Figures 2, 3 and 4, the hydraulic control device comprising a throttle valve 4 and a flow sensitive piston cylinder 32, the throttle valve 4 being connected in series In the oil inlet path of the directional control valve 10, the flow sensitive piston cylinder 32 includes a closed piston cylinder 329 and a piston 328 axially reciprocally disposed in the piston cylinder 329. The piston 328 is connected to the piston 328. a first piston rod 327 of the first end wall 3281 of the piston barrel 329, the first piston rod 327 is coupled to a spring of the valve core of the pilot flow control valve, thereby adjusting the force acting on the spring Adjusting a position of a spool of the pilot flow control valve, a first cavity 322 is defined between the piston 328 and the first end wall 3281, the piston 328 and the second end A second cavity 321 is defined between the walls 3282, and the first cavity 322 is connected to a downstream portion of the throttle valve 4 of the oil inlet path of the directional control valve 10, the second cavity 321 and the directional control valve 10 The upstream portion of the throttle valve 4 of the inlet passage is connected.

How to achieve the object of the present invention using the above-described hydraulic control device will be described in detail below with reference to Figs. 3 and 4.

For the pilot flow control valve (30), hydraulic oil flowing through the bypass throttle circuit flows from the bypass outlet C to the inlet 301 and then from the outlet 302 to the tank. At the first control port 303, the control pressure of the hydraulic oil is the system pressure P entering the directional control valve 10, and the control area is Al. In the second control port 304, since the second control port 304 is in communication with the bypass throttle circuit, the control pressure of the hydraulic oil is the pressure P2 of the hydraulic oil entering the inlet 301 of the pilot flow control valve and the valve of the valve 30. The sum of the elastic forces Fo of the springs of the core, the control area is A2. Therefore, for a liquid-controlled flow control valve, the force balance equation is P*Al=P2*A2+Fo (Formula 1). Since A1=A2, let A1=A2=A, it can be concluded that P-P2=Fo/A. Since A is constant for a particular valve 30, P-P2 is a constant. That is, after the throttling of the bypass throttling circuit, the pressure difference of the hydraulic oil is fixed. Specifically, the pressure difference of the hydraulic oil on both sides of the bypass throttle grooves 12 and 15 is fixed and is not affected by the load. Therefore, in the case where the flow rate of the system supplied to the directional control valve 10 is constant, the flow rate of the hydraulic oil flowing through the bypass throttle circuit remains unchanged, thereby maintaining the flow rate of the hydraulic oil flowing through the actuator 20. constant. The purpose of achieving the oil flow of the actuator is independent of the load change.

Therefore, it is necessary to provide the oil return throttle 11 and the conventional hydraulic control circuit shown in FIG.

14 to reduce the impact of the load on the system, in the hydraulic control circuit shown in Figure 2, there is no need to set the return throttle slots 11 and 14, thus removing the back pressure, so that the system pressure is correspondingly reduced, to improve the system Efficiency and reduce maintenance costs.

For the flow-sensitive piston cylinder 32, assuming that the flow area of the throttle valve 4 is A6, the differential pressure Po-P before and after the throttle valve 4 increases as the flow rate of the inlet passage of the directional control valve 10 increases. Big (According to the small hole flow formula, Q = c _d , where c _d is the flow coefficient,

For hydraulic oil density). Since the first chamber 322 is connected to the downstream portion of the throttle valve 4 of the oil inlet passage of the directional control valve 10, the first chamber 322 is introduced into the pressure P of the oil inlet port of the directional control valve 10, and the control area is A5. Since the second chamber 321 is connected to the upstream portion of the throttle valve 4 of the oil inlet path of the directional control valve 10, the second chamber 321 introduces a system pressure Ρο, and the control area is Α4. Obviously, the above pressure Ρ is the pressure of the system hydraulic oil upstream of the throttle valve 4, and the pressure Ρ is the pressure of the hydraulic oil after the (downstream) throttle valve 4.

Therefore, the force balance formula of the piston 328 is: Po*A4=P*A5+Fo (Formula 2). Due to the presence of the first piston rod 327, the control area A5 of the first chamber 322 and the control area A4 of the second chamber 321 are slightly misaligned. Under the premise that the error can be neglected, that is, A4=A5, and let Α4=Α5=Α'. According to the above formula 2, Fo = (Po-P) *A'. Therefore, when the system flow rate Q is increased when the actuator 20 is actuated, the pressure difference Po-P on both sides of the throttle valve 4 is increased, thereby increasing Fo, and the pressure difference of the hydraulic oil in the bypass throttle circuit. The P-P2 is increased to increase the flow of hydraulic oil through the bypass throttle circuit. By rationally designing the above various parameters, it is possible to achieve the object of the present invention by increasing the flow rate of the hydraulic oil in the bypass throttle circuit to the same as the system flow rate when the actuator 20 is activated.

The calculation process is as follows: The flow rate of the hydraulic oil flowing through the bypass throttle circuit is Q2, wherein

: (P - P2)

Q2 = C _d * AV

P

2 * Fo

C, * A3 *

p * A

A——the force control area of the pressure compensating valve 31;

A' - the control area of the flow sensitive piston 32;

A3 - the flow area of the bypass throttling circuit (bypass chute 12 or 15);

A6 - Flow area of the throttle valve 4.

The above A, A' and A6 are fixed values, and A3 is decreased as the opening degree of the directional control valve 10 is increased. Therefore, as the opening degree of the directional control valve 10 is gradually increased, since the flow passage area of the bypass throttle groove 12 or 15 is gradually decreased, the flow rate through the bypass circuit is gradually decreased until the directional control valve 10 reaches the left Bit or right position (At this time, part of the hydraulic oil passes through the bypass circuit or there is no hydraulic oil as required). When the opening degree of the directional control valve 10 is constant and the system flow rate Q is constant, the flow rate Q2 of the hydraulic oil flowing through the bypass throttle circuit is also constant, so the flow rate of the hydraulic oil entering the actuator 20 is set. Q1 is also a fixed value. That is, when the system flow rate Q is constant, the flow rate of the hydraulic oil entering the actuator 20 is only related to the opening degree of the directional control valve 10; when the opening degree of the directional control valve 10 is a fixed value, A3 is a fixed value, and the system flow rate Q When increasing, the flow rate Q2 of the hydraulic oil flowing through the bypass throttle circuit is increased. By appropriately designing the above various parameters, the flow rate Q2 of the hydraulic oil flowing through the bypass throttle circuit can be equalized when the actuator 20 is started. The system flow Q, that is, the flow rate Q1 entering the actuator 20 can start from zero.

Preferably, as shown in FIG. 4, the piston 328 of the flow-sensitive piston cylinder 32 is further coupled with a second end wall 3282 extending in a direction opposite to the first piston rod 327 from the piston barrel 329. The second piston rod 326 is such that the control area A5 of the first chamber 322 coincides with the control area A4 of the second chamber 321 to reduce the presence of errors.

The hydraulic control device is not limited thereto. As shown in FIG. 5, the hydraulic control device may include a controller 50 and an electronically controlled valve 40 electrically connected to the controller 50. The output end of the electronic control valve 40 is connected to the a second control port 304 of the flow control flow control valve, thereby acting on the spool of the pilot flow control valve, the controller 50 controlling the flow according to the flow signal of the system pressure hydraulic oil (ie, the system flow rate Q) The pressure at the output of the electronically controlled valve 40. Preferably, the electronically controlled valve 40 is an electromagnetic proportional pressure reducing valve. Therefore, when the controller 50 knows that the actuator 20 is activated (ie, when the system flow rate Q is increased), the controller 50 can activate the electronically controlled valve 40 to adjust the position of the spool of the pilot flow control valve, thereby making the flow The flow rate Q2 of the hydraulic oil passing through the bypass throttle circuit is increased to a level equal to the system flow rate Q, achieving the object of the present invention.

Preferably, as shown in FIG. 2, the directional control valve 10 has the oil inlet port P, the oil return port T, two working oil ports A, B, and a bypass inlet constituting the bypass throttle circuit. P' and a valve bypassing the outlet C (such as a three-position six-way valve), and a bypass throttle groove 12, 15 is disposed between the bypass inlet P and the bypass outlet C. Both the port P and the bypass inlet P' are in communication with a system pressure (such as a system hydraulic oil pumped by the hydraulic pump), and the working ports A, B are respectively in communication with the actuator 11, the oil return port T is in communication with the oil tank, and the bypass outlet C communicates with the valve 30 and further communicates with the oil tank.

Specifically, as shown in FIG. 2, when the directional control valve 10 is in the first position (the left position in FIG. 1), the oil inlet port P communicates with a working oil port A, and the oil return port T is in communication with another working port B, the bypass throttle circuit is cut off (the flow area of the bypass throttle groove 12 is the smallest, that is, closed); in the directional control valve 10 is in the second position (Fig. 2 The oil inlet P is in communication with the other working port B, the oil return port T is in communication with the one port A, and the bypass throttle circuit is cut off (bypass section) The flow passage area of the flow channel 15 is the smallest, that is, closed; when the directional control valve 10 is at the intermediate position, the oil inlet port P and the oil return port T are both closed, and the bypass inlet P' is adjacent to the side The outlet port C communicates through the bypass throttle groove (at this time, the flow passage area of the bypass throttle groove is the largest).

Preferably, the actuator 11 can be a hydraulic motor, and the hydraulic control circuit is a swing control loop.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments, and various simple modifications of the technical solutions of the present invention may be made within the scope of the technical idea of the present invention. These simple variations are within the scope of the invention. It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without being contradictory, and are not limited to the reference relationship of the claims in the claims. . In order to avoid unnecessary repetition, the present invention will not be further described in various possible combinations.

In addition, any combination of various embodiments of the invention may be made, as long as it does not deviate from the idea of the invention, and should also be regarded as the disclosure of the invention.

Claims

Rights request

A hydraulic control circuit comprising a directional control valve (10) having a bypass throttle circuit and an actuator (20) coupled to the directional control valve (10), wherein the hydraulic pressure The control circuit further includes a valve (30) connected in series in the bypass throttle circuit to enable flow through the bypass throttle circuit when the actuator (20) is activated The flow rate of the hydraulic oil can be equal to the system flow supplied to the directional control valve (10).

2. The hydraulic control circuit according to claim 1, characterized in that the valve (30) is capable of remaining through the execution in the case where the system flow rate supplied to the directional control valve (10) is constant The flow rate of the hydraulic oil of the component (20) does not change.

3. Hydraulic control circuit according to claim 2, characterized in that the valve (30) correspondingly reduces the valve of the valve (30) as the load on the actuator (20) increases Flow passage section of the port; when the load on the actuator (20) is reduced, the valve (30) correspondingly increases the flow cross section of the valve port of the valve (30) so as to be in the direction In the case where the control valve (10) has a constant opening degree, the flow rate of the hydraulic oil flowing through the bypass throttle circuit does not change.

4. The hydraulic control circuit according to claim 1, wherein the hydraulic control circuit further comprises a fuel tank, and the valve (30) includes an inlet (301), an outlet (302), and a first control port (303). And a liquid control flow control valve of the second control port (304), the inlet (301) of the pilot flow control valve is in communication with the bypass outlet (C) of the directional control valve (10), the pilot flow An outlet (302) of the control valve is in communication with the fuel tank, and a first control port (303) of the pilot flow control valve is directly or indirectly connected to a system pressure of the hydraulic control circuit, and the second control port (304) a hydraulic control device that communicates with the bypass throttle circuit and is coupled to a spool that acts on the pilot flow control valve.

The hydraulic control circuit according to claim 4, wherein the first control port of the pilot flow control valve is in direct communication with the oil inlet of the directional control valve (10).

6. The hydraulic control circuit according to claim 4, wherein the hydraulic control device comprises a throttle valve (4) and a flow sensitive piston cylinder (32), the throttle valve (4) being connected in series In the oil inlet path of the directional control valve (10), the flow sensitive piston cylinder (32) includes a closed piston cylinder (329) and a piston (328) axially reciprocally disposed in the piston cylinder (329). The piston (328) is coupled to a first piston rod (327) extending from a first end wall (3281) of the cylinder (329), the first piston rod (327) and the pilot flow control valve a spring connection of the spool, a first cavity (322) defined between the piston (328) and the first end wall (3281), the piston (328) and the second end wall (3282) A second chamber (321) is defined between the first chamber (322) and a downstream portion of the throttle valve (4) of the oil inlet passage of the directional control valve (10), the second chamber (321) ) is connected to the upstream portion of the throttle valve (4) of the oil inlet path of the directional control valve (10).

7. The hydraulic control circuit according to claim 6, wherein the piston (328) of the flow sensitive piston cylinder (32) is further connected to extend in a direction opposite to the first piston rod (327). a second piston rod (326) of the second end wall (3282) of the cylinder (329).

8. The hydraulic control circuit according to claim 4, wherein the hydraulic control device comprises a controller (50) and an electronically controlled valve (40) electrically connected to the controller (50), the electronically controlled valve The output end of (40) is in communication with the second control port (304) to act on the spool of the pilot flow control valve, and the controller (50) is supplied to the directional control valve (10) The flow signal of the system flow controls the pressure at the output of the electronically controlled valve (40).

The hydraulic control circuit according to any one of claims 1-8, wherein the directional control valve (10) has an oil inlet (P), a return port (T), and two working a port (Α, Β) and a valve constituting a bypass inlet (Ρ') and a bypass outlet (C) of the bypass throttle circuit, at the bypass inlet (Ρ') and the bypass outlet (C) is provided with a bypass throttle groove, and the oil inlet port (Ρ) and the bypass inlet port (Ρ') are both in communication with the system pressure, and the working oil ports (A, Β) are respectively executed with the said The element (11) is in communication, and the bypass outlet (C) is in communication with the valve (30).

10. The hydraulic control circuit according to claim 9, wherein the oil inlet (Ρ) and a working oil port (Α) when the directional control valve (10) is in the first position Connected, the oil return port (Τ) is connected to another working oil port (Β), and the bypass throttle circuit is cut off;

When the directional control valve (10) is in the second position, the oil inlet port (Ρ) is in communication with the other working oil port (Β), the oil return port (Τ) and the one port port (Α) connected, the bypass throttle circuit is cut off;

When the directional control valve (10) is in the intermediate position, the oil inlet (Ρ) and the oil return port

(Τ) is all closed, and the bypass inlet (Ρ') and the bypass outlet (C) communicate with each other through the bypass throttle.

The hydraulic control circuit according to claim 1, wherein the actuator (20) is a hydraulic motor, and the hydraulic control circuit is a swing control circuit.