CN102562699B - Counterbalance valve, hydraulic cylinder telescoping control circuit and crane - Google Patents

Abstract

The balance valve comprises a main valve body (1) with a forward oil port (A) and a reverse oil port (B), and a main valve core (4), wherein the main valve core comprises a first action surface (A1) and a second action surface (A2) which are opposite, the first action surface is exposed in a first action cavity (3) communicated with the reverse oil port, the second action surface is exposed in a second action cavity (17) communicated with the reverse oil port through a damping groove (5), and the balance valve further comprises a pilot control module which enables the second action cavity to be selectively communicated with an oil drainage port through a pilot control oil port (X). In addition, the invention also provides a hydraulic cylinder telescopic control loop and a hydraulic crane. The invention adopts a pilot control mode, can obtain larger control ratio by controlling the size of the pilot piston rod, ensures that the descending speed-limiting control of the balance valve is more sensitive, has small influence on the opening degree of the main valve core by load pressure, does not generate frequent jitter, and has better working stability and excellent energy-saving effect.

Description

Counterbalance valve, hydraulic cylinder telescoping control circuit and crane

technical field

The present invention relates to a balance valve, in particular to a balance valve. On this basis, the present invention also relates to a hydraulic cylinder expansion and contraction control circuit provided with the balance valve. Furthermore, the invention also relates to a crane.

Background technique

The balance valve is a valve widely used in construction machinery equipment, which plays an important role in improving the working performance of some hydraulic working mechanisms of construction machinery, such as the lifting mechanism, luffing mechanism and telescopic mechanism of hydraulic cranes. Typically, these working mechanisms use hydraulic cylinders as hydraulic actuators, and the hydraulic cylinders need to be telescopically controlled through the hydraulic cylinder telescopic control circuit, and the balance valve is generally set on the working oil circuit connected to the rodless chamber of the hydraulic cylinder.

When the hoisting mechanism of a hydraulic crane descends with a load, if there is no balance valve, the hoisting mechanism will descend at an overspeed under the action of the load, which will easily cause engineering accidents. In order to prevent this dangerous phenomenon, it is necessary to set a balance valve on the descending oil circuit of the telescopic control circuit of the hydraulic cylinder (that is, the working oil circuit connected to the rodless chamber of the hydraulic cylinder), so as to prevent the weight from accelerating down. In addition, when the hoisting mechanism of the hydraulic crane lifts the load to a certain height and temporarily hovers due to the need for work, the balance valve is in a locked state, which can play a locking role and prevent the hydraulic oil in the rodless chamber of the hydraulic cylinder. Oil return, so that the load is supported at this height and will not drop due to the weight of the load. Of course, what needs to be explained here is that the balance valve is not limited to the application in the telescopic control circuit of the hydraulic cylinder, it is widely used in various hydraulic working mechanisms of construction machinery equipment, such as in the full hydraulic walking system When sliding at an overspeed, a balance valve also needs to be set in the hydraulic control circuit of the full hydraulic walking system. Therefore, as an independent valve, the balance valve can be applied to various application occasions known to those skilled in the art. In the following description, in order to help those skilled in the art understand, a typical hydraulic cylinder telescopic control circuit is mainly used as Examples are described.

The simplest balance valve is a valve composed of a one-way valve and a sequence valve connected in parallel, but this kind of balance valve is rarely used in construction machinery due to its unsatisfactory sealing and working stability. Specially designed balance valves are used on construction machinery equipment, such as the balance valve used in the telescopic control circuit of hydraulic cylinders disclosed in US Patent No. 6,098,647. This balance valve is a typical prior art balance valve used on construction machinery equipment.

Fig. 1 and Fig. 2 show the sectional structure schematic diagram and the hydraulic principle diagram of the balance valve in the prior art. As shown in Figure 1, the balance valve in the prior art mainly includes a valve body 101, a main valve core 102, a main valve spring 103, a return spring 105, and a pilot piston 104. The lock holding function and the speed limit function are described in detail below with reference to Fig. 1 and Fig. 2:

Ascending oil inlet state: the hydraulic oil is connected to the positive oil port A (generally through the oil circuit switching of the reversing valve in the telescopic control circuit of the hydraulic cylinder to make the oil into the forward oil port A), what needs to be added here is that for As far as the balance valve is concerned, its positive oil port means that when the oil is fed from the positive oil port, as long as the hydraulic oil has sufficient pressure, the balance valve will conduct, so that the hydraulic actuator (such as a hydraulic cylinder) will pass through the balance valve. ) oil supply; the reverse oil port means that when the oil is fed from the reverse oil port, if the balance valve is not controlled (such as hydraulic control), the balance valve will not conduct regardless of the pressure of the hydraulic oil , which is similar to the forward and reverse ports of the check valve. Referring to Fig. 1 and Fig. 2, when the oil inlet pressure of the positive oil port A is not established, the conical part of the main valve core 102 forms a sealing line contact with the valve body 101 under the pressure of the main valve spring 103, so that the forward direction The oil port A is not connected to the reverse oil port B, so the balance valve will not open; when the oil inlet pressure of the positive oil port A is sufficient, the oil inlet pressure pushes the main valve core 102 to overcome the elastic force of the main valve spring 103, so that The forward oil port A is connected to the reverse oil port B, and the balance valve is opened. At this time, for example, in the telescopic control circuit of the hydraulic cylinder, the hydraulic oil is supplied to the rodless chamber of the hydraulic cylinder through the balance valve, so that the piston rod of the hydraulic cylinder up, pushing the load up.

Lock-up hold state: when the forward oil port A does not enter oil and the pilot control oil port X has no pressure or the pressure is too small, the reverse oil port B communicates with the rodless cavity of the hydraulic cylinder, for example, under the pressure of the load, no The hydraulic oil in the rod cavity acts on the right side of the main valve core 102 through the throttling oil passage on the main valve core 102, so that the conical part of the main valve core 102 is under the joint action of the hydraulic oil and the main valve spring 103. Press against the circumferential ridge of the valve cavity in the valve body 101 to form a tighter seal, the reverse oil port B and the forward oil port A are in a cut-off state, so that the balance valve remains closed, and the rodless hydraulic cylinder The hydraulic oil in the cavity cannot return oil from the reverse oil port B through the forward oil port A, so as to realize the locking function, so that the load can be kept at a certain height for a long time.

Descending speed limit state: When the telescopic control circuit of the hydraulic cylinder needs to control the hydraulic cylinder to drive the load down, the hydraulic control is performed through the pilot control oil port X (the pilot control oil port X is generally connected to the working oil circuit of the rod cavity of the hydraulic cylinder, where the drain The oil port L is mainly used to discharge the hydraulic oil infiltrated in the return spring cavity), when the pressure of the hydraulic control oil port X is small, the pilot piston 104 cannot overcome the pretightening force of the return spring 105, and the pilot piston 104 is in the position shown in Figure 1 The rightmost extreme position shown; when the oil pressure of the pilot control oil port X gradually increases, so that the pilot piston 104 can be pushed to overcome the elastic force of the return spring 105, the pilot piston 103 moves to the left, and when it moves to the predetermined position, it starts to work with the main spool The left end of 102 contacts, and then with the increase of the control pressure, the pilot piston 104 pushes the main valve core 102 to overcome the elastic force of the main valve spring 103, so that the reverse oil port B communicates with the forward oil port A, so that the hydraulic cylinder does not work The hydraulic oil in the rod chamber can return to the oil, so as to realize the function of speed limit in descent.

As shown in Fig. 1, when the balance valve in the prior art realizes the function of decreasing the speed limit, the pilot piston 104 pushes the main spool 102 to move because the pilot oil control oil pressure acts on the pilot piston 104, so its control ratio is 1 /K (where K=D ² /d ² , D is the flow inner diameter of the valve chamber in the valve body 101 shown in Figure 1, and d is the diameter of the control oil acting surface of the pilot piston 104), that is, the load pressure and the control pressure The ratio of oil pressure, that is, under the condition that the load pressure is 1MPa, the control oil pressure needs to reach K×1MPa to push the main valve rod 102 (the above control ratio is only a theoretical value, which ignores the return spring 105 and the main valve. The elastic force influence of spring 103). Due to structural design reasons, this prior art balance valve has some insurmountable problems. For example, because D is determined by the flow capacity of the balance valve, this needs to be related to the working speed of the hydraulic working mechanism and the flow demand of the hydraulic actuator. and other factors, the hydraulic working mechanism selects a balance valve with matching flow capacity according to the application needs, so the size of D is relatively determined, and d belongs to the part of the control oil circuit, and it cannot be formed larger, otherwise it will lead to control oil flow. Therefore, the control ratio of the balance valve in the prior art is relatively large. In this case, although the balance valve can realize the function of descending speed limit in the process of descending speed limit, it is too sensitive to the change of load pressure. Once the load pressure changes slightly, the matching control oil pressure is required to change exponentially. Otherwise, the opening of the balance valve will change significantly, and during the working process of the hydraulic working mechanism, the load pressure often changes due to various reasons (especially in the hydraulic working mechanism using multi-stage telescopic cylinders), even if the load pressure Only slightly fluctuating, the opening of the balance valve will also change frequently, so that the balance valve in the prior art is easily affected by the load pressure, and is prone to frequent jitter and other unstable work; Relatively large, so the opening pressure of the balance valve is large when realizing the function of descending speed limit, resulting in large power loss. Therefore, the opening of the balance valve in this prior art is easily affected by the load, and its controllability is poor. Even when the oil pressure of the pilot control oil port X remains constant, it still cannot maintain a stable opening of the balance valve.

It can be seen from the above description that the main disadvantages of the balance valve of the prior art are: first, due to the structural reasons of the balance valve, its control ratio is unreasonable, thus the controllability is poor, and the work is unstable, although it can realize the decline Speed limit function, but the balance valve is too sensitive to the change of load pressure, prone to frequent vibration and other unstable work; second, the opening of the balance valve cannot be controlled relatively stably and reliably through the pilot control oil port X, even in light It is also difficult to achieve stable control when the load is high; thirdly, the control pressure is relatively high. In order to achieve a certain control ratio, the area of the control oil action surface of the pilot piston 104 is often artificially formed to be larger, resulting in even less ideal control sensitivity. And the energy loss is bigger.

Therefore, it is necessary to design a new type of balance valve to overcome or alleviate one or even all of the above-mentioned shortcomings of the prior art.

Contents of the invention

The technical problem to be solved by the present invention is to provide a balance valve, which not only can effectively realize the hydraulic function of the balance valve, but also has good controllability and stable operation.

On this basis, the further technical problem to be solved by the present invention is to provide a hydraulic cylinder telescopic control circuit, which can effectively realize the speed limiting function during the process of the hydraulic cylinder carrying a load and descending, and has good working stability , significantly improving the reliability of the control performance.

In addition, the present invention also provides a crane, which can effectively realize the functions of stable lifting of loads, locking and holding, and lowering speed limit, and has good working stability and relatively reliable control performance.

In order to solve the above technical problems, the present invention provides a balance valve, which includes a main valve body with a forward oil port and a reverse oil port, and a main valve core that can move in the valve cavity of the main valve body. The main spool is in a normally closed sealing position where the forward oil port and the reverse oil port are blocked under the action of the elastic pre-tightening force of the main spool spring, wherein the main spool includes the opposite first acting surface and The second acting surface, the first acting surface is exposed in the first acting chamber communicated with the reverse oil port, the force bearing direction of the second acting surface is the same as the acting direction of the elastic pre-tightening force and is exposed to the In the second action chamber communicated with the reverse oil port via a damping groove or a damping hole, there is an oil drain passage between the second action chamber and the oil drain port of the balance valve; the balance valve also includes A pilot control module, the pilot control module includes a reciprocating pilot piston with a pilot piston rod, a return spring, and a hydraulic control chamber located on one side of the pilot piston, and the pilot piston rod extends into the drain oil passage And under the action of the return spring, it forms a seal with the inner wall of the drain oil passage to block the drain oil passage. The hydraulic control chamber communicates with the pilot control oil port of the balance valve to receive the hydraulic control oil. And controlling the pilot piston to drive the pilot piston rod to move so as to make the drain oil passage conduct.

Preferably, the main spool spring chamber of the main spool spring doubles as the second action chamber.

Preferably, the second action chamber communicates with the reverse oil port through the damping groove, which is formed on the outer peripheral surface of the main valve core and communicates with the inner wall of the valve chamber of the main valve body. When the main valve core moves away from the normal sealing position, the flow opening of the damping groove is increased.

Specifically, a protrusion with an axial slope that cooperates with the damping groove is formed on the inner peripheral surface of the valve chamber of the main valve body, and the protrusion is in the process of moving the main valve core away from the normal sealing position. The distance between the center and the bottom wall of the damping groove is increased to increase the flow opening of the damping groove.

Preferably, the area of the first active surface is smaller than the area of the second active surface.

Preferably, a throttling groove is formed on the pilot piston rod, and the opening of the throttling groove increases as the pilot piston rod moves away from a position sealed with the inner wall of the oil drain passage.

Specifically, the drain oil channel includes a piston rod matching through hole, and the pilot piston rod extends into the piston rod matching through hole and forms a cone with the piston rod matching through hole under the action of the return spring. face seal.

Specifically, the pilot piston rod includes a throttle groove section whose cross-sectional area continuously decreases to form the throttle groove with a continuously increasing cross-sectional area on the pilot piston rod. When the pilot piston rod moves away from the position where it is sealed with the piston rod matching through hole, the throttle groove segment moves through the piston rod matching through hole to increase the flow opening of the throttle groove.

Specifically, the pilot control module includes a pilot valve body integrally formed with the main valve body or installed on the main valve body, and a pilot plunger cavity communicated with the through hole through the piston rod is formed in the pilot valve body and the pilot piston cavity, the pilot plunger cavity communicates with the second action cavity, the pilot piston cavity is provided with the slidable pilot piston and is sealed and separated into the return spring cavity and the said pilot piston cavity In the hydraulic control chamber, the return spring is provided in the return spring chamber, and the oil drain port is provided on the wall of the return spring chamber.

Specifically, one end portion of the pilot piston rod is formed as the conical sealing section that is sealed with the through hole of the piston rod, the conical sealing section is formed with a communication oil passage, and the conical sealing section is connected to There is a guide plunger sealingly matched with the inner peripheral surface of the guide plunger chamber, the guide plunger is provided with a fixed damping hole connecting the communication oil passage and the second action chamber, and the oil drain passage is formed by the It consists of a fixed damping hole, a connecting oil passage, a piston rod matching through hole, a throttling groove and a return spring chamber.

Alternatively, one end portion of the pilot piston rod is provided with a taper fitting that is sealed with the fitting through hole of the piston rod, and the taper fitting is located in the cavity of the pilot plunger and fixed to On the pilot piston rod, the drain oil channel is composed of the pilot plunger cavity, the piston rod matching through hole, the throttling groove and the return spring cavity.

Alternatively, one end of the pilot piston rod is connected to or formed with a sealing post located in the guide plunger chamber and spaced from the inner peripheral surface of the guide plunger chamber, and the seal post has a Cooperate with the tapered part of the through hole sealing fit, the oil drain oil passage is composed of the guide plunger cavity, the piston rod matching through hole, the throttling groove and the return spring cavity.

Specifically, the main valve body is provided with a main valve sleeve, the valve chamber of the main valve body is formed by the main valve sleeve, and the first action chamber, the second action chamber and the spring chamber of the main valve core pass through the main valve sleeve. The valve core is formed by cooperation with the main valve sleeve.

On the basis of the above-mentioned balance valve technical solution, the present invention also provides a hydraulic cylinder telescopic control circuit, the hydraulic cylinder telescopic control circuit includes a balance valve and a reversing valve, wherein the balance valve is any one of the above-mentioned technical solutions For the balance valve, the forward oil port of the balance valve is connected with a working oil port of the reversing valve, the reverse oil port is connected with the rodless chamber of the hydraulic cylinder, and the pilot control oil port is connected with the hydraulic pressure The working oil circuit of the rod cavity of the cylinder is connected, and the oil discharge port is connected with the oil tank or the oil return circuit.

In addition, the present invention also provides a crane, wherein the crane includes the above hydraulic cylinder telescopic control circuit.

Through the above technical solution, the balance valve of the present invention selectively makes the second action chamber (preferably, the spring chamber of the main valve core also serves as the second action chamber) communicate with the oil tank or the return oil circuit through the movement of the pilot piston rod, Therefore, the movement of the main spool is controlled by controlling the movement of the pilot piston rod. It adopts the pilot control method, so it is only necessary to control the shape and size of the pilot piston rod to easily obtain a large control ratio, which makes the drop limit of the balance valve The speed control is more sensitive, and the opening of the main spool can be effectively controlled by a small control oil pressure, and the opening of the main spool is not greatly affected by the load pressure, which mainly depends on the oil pressure at the pilot control oil port. Therefore, frequent vibrations will not occur due to slight changes in load pressure, and the working stability is better. In addition, in a preferred manner, the second action chamber communicates with the reverse oil port through the damping groove that can increase the flow capacity and reduce the damping effect as the main valve core moves axially, which can make the balance valve control effect of the present invention More preferably, a relative dynamic balance is formed between the first action chamber and the second action chamber, so as to avoid excessive opening of the main valve core. In addition, the pilot piston rod can be integrated with a throttling groove, and the throttle groove gradually increases its opening with the movement of the pilot piston rod when the pilot control oil port has sufficient oil pressure, or when the oil pressure of the pilot control oil port When the pressure decreases, the opening is gradually reduced, so the working stability is better, and the impact phenomenon during the working process is avoided. At the same time, since the length of the second flow groove on the pilot piston rod can be formed longer, the controllability is better. In addition, since the required control oil pressure is small, the energy saving effect is good. Apparently, since the telescoping control circuit of the hydraulic cylinder and the hydraulic crane of the present invention include the above-mentioned balance valve of the present invention, they also have the above-mentioned technical advantages.

Other features and advantages of the present invention will be described in detail in the following detailed description.

Description of drawings

The following drawings are used to provide a further understanding of the present invention, and constitute a part of the description, which are used together with the following specific embodiments to explain the present invention, but the scope of protection of the present invention is not limited to the following drawings and specific implementation Way. In the attached picture:

Fig. 1 and Fig. 2 are respectively a sectional structure schematic diagram and a hydraulic principle diagram of a balance valve in the prior art.

Fig. 3 is a schematic cross-sectional structure diagram of a balance valve according to a specific embodiment of the present invention.

Fig. 4 is a partially enlarged schematic view of the throttle groove on the pilot piston rod of the balance valve shown in Fig. 3 .

Fig. 5 is a schematic diagram of the hydraulic principle of the balance valve according to the specific embodiment of the present invention shown in Fig. 3 .

Fig. 6 and Fig. 7 are partial enlarged schematic diagrams of two other specific implementation forms of the throttling groove on the pilot piston rod of the balance valve of the present invention respectively.

Explanation of reference numerals of the present invention:

1 main valve body; 2 main valve sleeve;

3 first action chamber; 4 main spool;

5 Damping groove; 6 Main spool spring;

7 main spool spring chamber; 8 guide plunger;

9 fixed damping hole; 10 connected oil passage;

11 guide plunger cavity; 12 pilot valve body;

13 return spring cavity; 14 return spring;

15 pilot piston rod; 16 pilot piston;

17 second action chamber; 18 hydraulic control chamber;

19 oil drain passages;

136 guide the inner peripheral surface of the plunger cavity;

137 sealing column; 138 lock nut;

139 taper fittings; 140 taper sealing section;

141 Piston connecting section; 142 First throttle section;

143 second throttle section; 144 third throttle section;

145 throttle groove; A positive oil port;

B reverse oil port; A1 first action surface;

A2 second action surface; L oil drain port;

P1 The oil pressure in the first action chamber;

P2 Oil pressure in the second action chamber;

X pilot control port.

Detailed ways

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and the protection scope of the present invention is not limited to the following specific embodiments. .

First of all, it needs to be explained that the balance valve of the present invention is a hydraulic component, and its core technical concept lies in its hydraulic control relationship, not in the specific valve structure. The specific valve structures shown in Fig. 3, Fig. 4 and Fig. 6 and Fig. 7 are only specific structural forms to help those skilled in the art to understand, but the protection scope of the present invention should not be limited to these specific structural forms, for example , as far as the hydraulic control relationship of the preferred form of the balance valve of the present invention shown in FIG. As long as it adopts the hydraulic control relationship of the balance valve of the present invention, it belongs to the scope of protection of the present invention.

In order to help those skilled in the art deeply understand the technical solution of the present invention, a preferred specific structural form of the balance valve of the present invention is first described below with reference to Figure 3 and Figure 4, so that those skilled in the art can initially form the technical solution of the present invention relatively intuitive understanding. However, the protection scope of the present invention is not limited to the detailed structure shown in Fig. 3 and Fig. 4, for this reason on the basis of the preferred valve structure, the present invention will be further described on a more generalized level (ie hydraulic control relationship level) technical solutions.

As shown in Figure 3, the illustrated balance valve includes a main valve body 1 formed with a forward oil port A and a reverse oil port B, a main valve sleeve 2, a main valve core 4, a main valve core spring 6, a pilot valve body 12. Return spring 14, pilot piston 16, pilot piston rod 15, etc., in which the main valve core 4 and the main valve sleeve 2 are matched in the axial direction, a conical mating surface to form a conical surface seal, a cylindrical mating surface, the main valve The core 4 forms a tapered seal with the main valve sleeve 2 under the action of the elastic pre-tightening force of the main valve core spring 6, so as to be in a normal sealing position that cuts off the forward oil port A and the reverse oil port B.

At the same time, the main spool 4 also includes a first action surface A1 for being pressurized to drive the main spool to leave the normal sealing position and for being pressurized to make the main spool 4 maintain or move to the normal sealing position. The second action surface A2, the first action surface A1 is exposed in the first action chamber 3 communicating with the reverse oil port B, that is, the first action surface A1 and the main valve sleeve 2 jointly enclose the first action chamber 3. To be able to receive the hydraulic oil from the reverse oil port B and withstand the pressure of the hydraulic oil, the second acting surface A2 is exposed to the main spool spring chamber 7 communicated with the reverse oil port B via the damping groove 5, the The main spool spring chamber 7 is jointly surrounded by the second action surface A2, the main valve sleeve 2 and the sides of the pilot valve body 12. In the embodiment shown in FIG. The second action chamber where the main spool 4 moves, the damping groove 5 is formed on the outer peripheral surface of the main spool 4, and the damping groove 5 is also shown in the hydraulic schematic diagram shown in FIG. 5 . Preferably, the damping groove 5 follows the main spool 4 from the normal sealing position where the reverse oil port B and the forward oil port A are blocked to the controlled conduction position where the reverse oil port B and the forward oil port A are connected. It is easy for those skilled in the art to understand that the flow opening is increased during the movement of the through position. This is generally achieved by the cooperation between the main valve core 4 and the inner peripheral surface of the main valve sleeve 2, for example, on the main valve core 4 A damping groove 5 is formed, and a protrusion with an axial gradient matched with the damping groove 5 is formed on the inner peripheral surface of the main valve sleeve 2. As the main valve core 4 moves relative to the main valve sleeve 2, the protrusion and the damping The distance between the bottom wall of the groove 5 increases, thereby increasing the opening of the damping groove 5 and increasing the flow capacity. One end of the main spool spring 6 is installed on the protrusion at one end of the main spool 4 , while the other end is installed and supported on the side of the pilot valve body 12 . The pilot piston rod 15 can be axially assembled with the guide plunger 8 by means of welding, riveting or the like. The pilot plunger 8 is located in the pilot plunger chamber 11 of the pilot valve body 12 and cooperates with the inner peripheral surface of the pilot plunger chamber 11 of the pilot valve body 12 to make the movement of the pilot piston rod 16 more stable. A fixed damping hole 9 and a communication oil passage 10 communicating with the fixed damping hole are formed in the guide plunger 8 , and the main valve core spring chamber 7 communicates with the guide plunger cavity 11 through the fixed damping hole 9 and the communication oil passage 10 .

The pilot valve body 12 is sealed and installed on the main valve body 1, and a pilot plunger chamber 11 and a pilot piston chamber are formed in the pilot valve body 12, and the pilot plunger chamber 11 and the pilot piston chamber pass through the pilot valve body 12. The piston rod is connected with the through hole 20, the pilot plunger chamber 11 is communicated with the main valve core spring chamber 7, and the pilot piston chamber is provided with a slidable pilot piston 16, which is sealed and separated into a return spring chamber 13 and a hydraulic pressure chamber by the pilot piston 16. The control chamber 18 and the hydraulic control chamber 18 communicate with the pilot control oil port X of the balance valve to receive the hydraulic control oil and control the pilot piston 16 to drive the pilot piston rod 15 to move. A return spring 14 is provided in the return spring chamber 13 , and an oil drain port L is provided on the wall of the return spring chamber 13 . The pilot piston rod 15 extends into the piston rod matching through hole 20 and forms a cone seal with the piston rod matching through hole 20 under the action of the return spring 14. When the hydraulic oil pressure in the hydraulic control chamber 18 is sufficient to overcome the return spring 14 and the pressure of the hydraulic oil in the main spool spring cavity 7 on the pilot piston rod 15, the pilot piston rod 15 is driven to move away from the position that is sealed with the through hole 20 of the piston rod. The structure of the pilot piston rod 15 and the tapered surface seal of the piston rod matching through hole 20 and the throttling groove 145 on the pilot piston rod are shown in Figure 4. The throttling groove section and the piston connecting section 141, wherein a conical seal is formed between the conical sealing section 140 of the pilot piston rod 15 and the piston rod fitting through hole 20, and the conical section forms a conical sealing surface. In order to form the throttle groove 145 on the pilot piston rod 15, the cross-sectional area of the throttle groove section of the pilot piston rod 15 needs to have a corresponding change, so that the throttle groove section of the pilot piston rod 15 forms a corresponding throttle groove 145 , specifically, the throttle groove section of the pilot piston rod 15 can be subdivided into three sections, and there is only a small gap between the first throttle groove section 142 and the inner peripheral surface matched with the piston rod matching through hole 20, and the following The cross-sectional area of the second throttling groove section 143 decreases gradually; then the cross-sectional area of the third throttling groove section 144 continues to gradually decrease and finally remains unchanged. The cross-sectional area of the piston connection section 141 of the pilot piston rod 15 , which is connected to the pilot piston 16 , is the same as the cross-sectional area of the first throttle groove section 142 . One end of the return spring 14 is installed on the side of the pilot piston 16 , and the other end is installed and supported on the inner side of the return spring cavity 13 of the pilot valve body 12 .

It can be seen from the above description that the main technical feature of the balance valve in the preferred embodiment above is that it adopts the pilot control mode, and the opening of the main valve core is controlled by controlling the movement of the pilot piston rod. The control ratio of the balance valve can be approximately considered as D ² /d ² , where D is the outer diameter of the pilot piston 16, and d is the outer diameter of the piston connection section 141 of the pilot piston rod 15, that is to say, the small control oil pressure at the pilot control oil port X can make The main spool 4 is open, and even if the load pressure changes slightly, the opening of the main spool of the balance valve will not change sensitively, so the work is more stable and reliable, and it is not easy to produce unstable phenomena such as jitter, and the control is more sensitive. Good control. In addition, the balance valve also has the following structural features: first, the balance valve integrates the throttle groove that controls the movement of the main valve core 4 of the balance valve on the pilot piston rod, and the throttle groove is on the pilot piston rod. The throttling groove sections 142, 143, 144 are formed continuously, and the flow opening is changed. As the pilot piston rod 15 moves to the left as shown in FIG. 3, the flow opening increases, and when it moves to the right, the flow opening decreases. Through flow opening, it improves the performance of the balance valve through a simplified structure; second, the balance valve makes the main valve core spring chamber 7 double as the second action chamber, thereby making the balance valve structure of the present invention more compact, the main valve The core spring chamber 7 communicates with the reverse oil port through the damping groove 5 that can increase the flow capacity and reduce the damping effect as the main valve core moves axially, which can make the balance valve control effect of the present invention better, making the formation of the first A relative dynamic balance is formed between the first action chamber and the second action chamber to avoid excessive opening of the main valve core; thirdly, the balance valve forms a fixed damping hole 9 in the guide plunger 8 so that the main The pressure relief of the spool spring chamber 7 is too fast, thereby ensuring the smooth movement of the main spool spool; fourth, the pilot piston rod is integrated with a throttle groove 145, which has enough oil at the pilot control oil port. When pressing, the opening is gradually increased with the movement of the pilot piston rod, or the opening is gradually reduced when the oil pressure of the pilot control oil port decreases, so the working stability is better and the impact phenomenon during the working process is avoided. Because the main function of the throttling groove on the pilot piston rod 15 is to reduce the pressure of the spring chamber 7, the installation positions of the pilot piston 16, pilot piston rod 15 and pilot valve body 12 can be selected according to specific conditions, and can be installed in the The axial position shown in 3 can also be installed at a position with a certain angle to the axis of the balance valve, and can also be installed in a plane perpendicular or non-perpendicular to the axis, and is not limited to the specific form shown in Figure 3 .

In addition, it should be noted that the above description is only the preferred structural form of the balance valve of the present invention, but the balance valve of the present invention is not limited to the above specific structural form. The guide plunger 8 and the fixed damping hole 9 can also be eliminated, and the tapered fitting 139 is fixed by a lock nut 138 at one end of the pilot piston rod 15. The conical sealing section of the piston rod 15 is similar, mainly through the conical surface on the conical surface fitting 139 and the through hole 20 of the piston rod of the pilot valve body 12 to form a conical seal, and it can also play a role in the pilot piston rod 15. The stop function prevents the pilot piston rod 15 from excessively moving and losing the effective position of normal work. Similar to the above-mentioned preferred mode, the pilot piston rod 15, the pilot piston 16, the pilot valve body 12, the taper fitting 139, and the lock nut 138 can be It is installed at the axial position of the balance valve, but it can also be installed at a position with a certain angle to the axis of the balance valve, or in a plane perpendicular or non-perpendicular to the axis of the balance valve. For another example, referring to Fig. 7, the guide plunger 8 and the fixed damping hole 9 of the above-mentioned preferred specific form can also be replaced by the sealing column 137 shown in Fig. There is no matching requirement on the surface, and the diameter of the sealing post 137 is smaller than the diameter of the pilot plunger chamber (spacing from the inner peripheral surface of the pilot plunger chamber). In this way, the purpose of the present invention can also be achieved. However, it should be noted that in the alternative embodiment shown in Figures 6 and 7, the control ratio of the counterbalance valve is slightly reduced compared to the control ratio of the preferred configuration described above, because the taper fitting 139 or The diameters of the sealing columns 137 are larger than the diameter of the piston rod connecting section 141 of the pilot piston rod 15 shown in FIG. The diameter of the sealing post 137 is calculated. However, obviously, in these two alternative implementations, the balance valve of the present invention still controls the opening degree of the main spool 4 by controlling the movement of the pilot piston rod 15 itself, so the control ratio can be optimized relatively easily, significantly The working stability can be greatly improved, and the control sensitivity can be enhanced, so as to significantly improve the working performance of the balance valve, and the opening of the main spool can be controlled by controlling the opening of the throttling groove 145, so as to achieve a certain degree of approximation proportional control function.

What needs to be repeatedly explained here is that it can also be seen from the alternative embodiments shown in Figure 6 and Figure 7 that within the scope of the technical concept of the balance valve of the present invention, those skilled in the art can make various specific structures deformation, but as long as these structural deformations belong to the technical concept of the present invention, they shall belong to the protection scope of the present invention. The main technical idea of the present invention lies in its core hydraulic control principle, and the protection scope of the present invention should not be limited to any specific detailed structure.

For this reason, the following will mainly refer to Fig. 5 to describe the technical solution on the level of the technical conception in a broader sense of the present invention. For better understanding of the structure, reference may be made to Figure 3 as appropriate.

Referring to Fig. 3, as described above, the main valve part of the balance valve of the present invention is basically similar to the balance valve of the prior art, that is, the balance valve includes a main valve body 1 with a forward oil port A and a reverse oil port B And the main spool 4 that can move in the valve chamber of the main valve body 1 to control the on-off of the forward oil port A and the reverse oil port B, the main spool 4 is under the elastic preset of the main spool spring 6 Under the action of tight force, it is in the normally closed sealing position where the forward oil port A and the reverse oil port B are cut off. This kind of seal generally adopts a conical surface seal, for example, the conical surface at one end of the main valve core 4 in Fig. The main valve sleeve 2 in the valve cavity of the main valve core 4 forms a tapered seal, and the other end of the main valve core 4 is pressed against the main valve sleeve 2 by the pre-tightening elastic force of the main valve core spring 6, thereby It is formed so that the main valve core 4 is in the normal sealing position, so as to block the forward oil port A and the reverse oil port B.

Different from the prior art, the main spool 4 also includes a first action surface A1 for being pressurized to drive the main spool to leave the normal sealing position and for being pressurized so that the main spool 4 maintains or The second acting surface A2 that moves to the normal sealing position, that is to say, the main valve core 4 includes the opposite first acting surface A1 and the second acting surface A2, wherein the direction of the first acting surface bearing the hydraulic oil pressure is the same as that of the first acting surface The pressure direction of the second action surface is opposite, and the force direction of the second action surface A2 is the same as the action direction of the elastic pre-tightening force of the main valve core spring 6, that is, the main valve core 4 can be kept in or moved to the normal state. Trends in seal position. Wherein, the first working surface A1 is exposed in the first working chamber communicated with the reverse oil port B, so as to be able to receive the hydraulic oil from the reverse oil port B and bear the pressure of the hydraulic oil; the second working surface A2 It is exposed to the second action chamber 17 that communicates with the reverse oil port B through the damping groove 5 or the damping hole, so as to receive the hydraulic oil from the reverse oil port B through the damping groove 5 or the damping hole and bear the pressure of the hydraulic oil , it should be noted here that due to the effect of the damping groove 5 or the damping hole, the oil pressure in the second action chamber 17 is generally lower than the oil pressure in the first action chamber 3 during the dynamic operation of the balance valve. When the second action chamber 17 is closed (for example, the balance valve is locked and maintained), the oil pressure of the hydraulic oil in the second action chamber 17 needs a certain period of time to accumulate to reach the same pressure as the hydraulic oil pressure in the first action chamber 3. The extent, that is to say, there is a certain reaction time difference. The specific structural forms of the first action chamber 3 and the second action chamber can be varied. For example, in the preferred structure shown in the above-mentioned FIG. In this way, there is no need to independently form the second action chamber 17 on the physical structure of the valve, thereby simplifying the structure. In this case, the second action surface A2 is the right end surface of the main valve core 4 shown in FIG. The end face of the main spool body and the end face of the boss used to install the main spool spring 6), of course, the main spool spring chamber 7 may not be used as the second action chamber 17, in this case it is necessary to set an independent second Action chamber 17. In addition, a drain oil channel 19 is provided between the second action chamber 17 and the oil drain port L of the balance valve. For example, in the above-mentioned FIG. The piston rod between the oil channel 10, the return spring chamber 13 on the pilot valve body 12 and the guide plunger chamber 11 is formed by the through hole 20, the throttling groove 145 and the return spring chamber 13; and in Fig. 6 and Fig. 7 In an alternative modified embodiment, the oil discharge oil passage 19 is composed of a guide plunger chamber 11 , a piston rod fitting through hole 19 , a throttling groove 145 and a return spring chamber 13 . Apparently, those skilled in the art can also think of various other specific structural forms, but these simple modified structures should all belong to the protection scope of the present invention.

In addition, the balance valve of the present invention also includes a pilot control module, the main part of which is actually a control cylinder, referring to Figure 3 as appropriate, the pilot control cylinder module includes a pilot with a pilot piston rod 15 capable of reciprocating movement Piston 16, return spring 14 acting on the pilot piston 16, and a hydraulic control cavity 18 located on one side of the pilot piston 16, the pilot piston rod 15 extends into the oil drain passage 19 and Under the action of the return spring 14, it forms a seal with the inner wall of the drain oil passage 19, thereby blocking the drain oil passage. The hydraulic control chamber 18 communicates with the pilot control oil port X of the balance valve, so that it can receive the hydraulic control oil to drive the pilot piston. 16 moves, and the pilot piston 16 drives the pilot piston rod 15 to move away from the position where it forms a seal with the inner wall of the drain oil passage 19, so that the drain oil passage 19 conducts, and the second action chamber 17 is connected to the drain oil passage. The oil port L is connected to discharge the hydraulic oil in the second working chamber, so that the hydraulic oil in the second working chamber 17 decreases.

The basic technical solution on the level of hydraulic control relationship of the present invention has been described above, and the technical concept of the basic technical solution includes various possible specific valve structures within the scope of the present invention. Therefore, it needs to be emphasized again that no matter how the specific structure of the balance valve is modified, as long as it adopts the above-mentioned hydraulic control relationship of the present invention, it shall fall within the scope of protection of the present invention. On the basis of the above-mentioned technical solutions, the balance valve of the present invention also includes some preferred specific structures, such as the above-mentioned structure in which the main valve core spring chamber 7 doubles as the second action chamber 3, Fig. 3, Fig. 6 and Fig. The specific structural form of the drain oil channel 19 in 7. Some other preferred structural forms of the balance valve of the present invention will be described below. These structural forms have been properly described in the preferred mode with reference to FIG. 3 above, so they are only briefly described below.

In the above basic technical solution, the second action chamber 17 communicates with the reverse oil port B through the damping groove 5 or the damping hole, that is to say, as long as there is damping between the second action chamber 17 and the reverse oil port B The flow of the function is sufficient. However, preferably, the second action chamber 17 communicates with the reverse oil port B through a specific damping groove 5 formed on the outer peripheral surface of the main valve core 4 and connected to the main valve body 1 The cooperation of the inner wall of the valve cavity increases the flow opening of the damping groove 5 when the main valve core 4 moves away from the normal sealing position. That is to say, the damping groove 5 is a damping groove that can increase the flow capacity and reduce the damping effect as the main valve core moves axially, that is, the damping groove that the flow opening can be changed, which can make the balance valve of the present invention The control effect is better, so that a relative dynamic balance is formed between the first action chamber and the second action chamber, and the excessive opening of the main valve core is avoided. Specifically, this type of damping groove 5 can be realized through various specific structures, for example, as mentioned above, specifically, a damping groove 5 is formed on the outer peripheral surface of the main valve core 4, and the inner peripheral surface of the valve chamber of the main valve body (For example, the inner peripheral surface of the main valve sleeve 2) is formed with a projection with an axial slope that matches the damping groove 5 (the projection has a predetermined length). As the valve cavity moves, the distance between the protrusion and the bottom wall of the damping groove 5 increases to increase the flow opening of the damping groove 5 , thereby increasing the flow capacity of the damping groove 5 . Of course, those skilled in the art can realize the above-mentioned axially variable flow opening through various structures for the damping groove 5 , which will not be repeated here.

In addition, the area of the first action surface A1 can be smaller than the area of the second action surface A2, but this is not necessarily the case. By selecting the main valve core spring 6 with different elastic coefficients, the area of the first action surface A1 can also be Of course, in the preferred embodiment shown in Figure 3, since the main spool spring chamber 7 preferably doubles as the second action chamber 17, obviously the area of the first action surface A1 can be less than The area of the second acting surface A2.

In order to make the balance valve run more smoothly and avoid the impact of instantaneous flow interruption or conduction, a throttle groove 145 is formed on the pilot piston rod 15, and the flow opening of the throttle groove 145 moves away from the pilot piston rod 15. The sealing position with the inner wall of the oil drain passage 19 is increased. Specifically, for example, as described above with reference to FIG. 3 , the drain oil passage 19 includes a piston rod matching through hole 20, and the pilot piston rod 15 extends into the piston rod matching through hole 20 and is connected to the piston rod under the action of the return spring 14. The rod fits through hole 20 to form a cone seal. The pilot piston rod 15 includes throttling groove sections 142, 143, 144, the cross-sectional area of which throttling groove section continuously decreases to form a throttling groove 145 with a continuously increasing cross-sectional area on the pilot piston rod 15, so When the pilot piston rod 15 moves away from the sealing position with the piston rod matching through hole 20, the throttle groove segments 142, 143, 144 move through the piston rod matching through hole 20 to increase the throttle groove 145 flow capacity.

Specifically, referring to FIG. 3 , the above-mentioned pilot control module of the present invention includes a pilot valve body 12 that is integrally formed with the main valve body 1 or sealed and installed on the main valve body 1 . The piston rod cooperates with the guide plunger chamber 11 and the pilot piston chamber communicated with the through hole 20. The guide plunger chamber 11 communicates with the second action chamber 17. This communication can have various forms, and is not limited to that shown in FIG. 3 specific form shown. As mentioned above, the specific structure of the pilot control module is actually a control cylinder, the pilot piston chamber is provided with a slidable pilot piston 16, and the pilot piston chamber is separated into a return spring chamber 13 and a hydraulic control chamber by the pilot piston 16 18. The return spring 14 is provided in the return spring chamber 13, and the return spring 14 has a certain elastic pre-tightening force acting on the pilot piston 16, so that the tapered end of the pilot piston rod 15 or the seal is pressed against to the piston rod fitting hole 20 to form a cone seal. In addition, the oil drain port L is arranged on the cavity wall of the return spring cavity 13 . The main valve body 1 is provided with a main valve sleeve 2, the valve chamber of the main valve body 1 is formed by the main valve sleeve 2, and the first action chamber 3, the second action chamber 17 and the main valve core spring chamber 7 pass through the main valve body. The core 3 is formed by cooperating with the main valve sleeve 2 . In addition, some other preferred structures have been described above in the preferred specific implementation manner with reference to FIG. 3 , and will not be described again.

The working principle of the balance valve in the preferred embodiment of the present invention will be described below mainly with reference to FIG. 3 , FIG. 3 and FIG. 5 , so as to better reflect the advantages of the balance valve of the present invention.

The working principle of the balance valve is shown in Figure 5, where the application of the balance valve to the hydraulic cylinder telescopic control circuit of the hydraulic crane hoisting mechanism is taken as an example. One of the working oil ports is connected, the reverse oil port B is connected with the rodless chamber of the hydraulic cylinder, and the pilot control oil port X is connected with the working oil circuit of the rod chamber of the hydraulic cylinder. In this case, the working state of the balance valve is divided into ascending oil inlet state (hydraulic oil flow direction is forward oil port A→reverse oil port B), lock holding state, and descending speed limit state (hydraulic oil flow direction Reverse oil port B→forward oil port A).

Rising oil inlet state: When the hydraulic oil pressure established at the forward oil port A is sufficient to overcome the elastic force of the main spool spring 6, the hydraulic oil pushes the main spool 4 to move, thus making the forward oil port A and the reverse oil port B Connected, the hydraulic oil enters the rodless chamber of the hydraulic cylinder from the forward oil port A through the reverse oil port B, thereby pushing the piston rod of the hydraulic cylinder to rise, so that the lifting mechanism of the hydraulic crane can lift the load;

Locking and holding state: when the lifting mechanism of the hydraulic crane lifts the load to a certain height, and the load hovers at this height due to the needs of the operation, the hydraulic cylinder telescopic control circuit stops supplying oil to the hydraulic cylinder, and the load is at The oil pressure generated by the reverse oil port B enters the main spool spring cavity 7 through the damping groove 5, and the pressure in the main spool spring cavity 7 and the pretightening force of the main spool spring 6 work together to press the main spool 4 against the main spool. A tapered seal is formed on the valve sleeve 2, even if the main valve core spring 6 is damaged, the oil pressure in the main valve core spring chamber 7 can ensure its reliable sealing, so that the forward oil port A and the reverse oil port B are cut off. At the same time, at this time, because the telescopic control circuit of the hydraulic cylinder stops supplying oil to the hydraulic cylinder, there is no oil pressure at the pilot control oil port X, and the pilot piston 16 is at the rightmost end of the stroke under the pretightening force of the return spring 14, and the pilot piston rod 15 The conical sealing surface of the conical sealing section 140 cooperates with the piston rod of the pilot valve body 12 to form a conical sealing of the through hole 20, thereby sealing the hydraulic oil in the spring chamber 7 of the main valve core. That is to say, the reliable sealing of the balance valve as a whole makes it impossible for the rod chamber of the hydraulic cylinder to return oil, so that the load cannot drop under its own weight, thus forming a locked state.

Descending speed limit state: when the hydraulic cylinder carries a load and descends, the telescopic control circuit of the hydraulic cylinder supplies oil to the rod cavity of the hydraulic cylinder, and the rodless cavity returns oil through the balance valve of the present invention. At this time, the pilot control oil port X is due to the hydraulic cylinder There is oil pressure on the working oil circuit of the rod cavity, so the pilot control oil port X establishes the oil pressure, when the oil pressure of the pilot control oil port X can overcome the elastic preload of the return spring acting on the pilot piston 16 and the main spool When the pressure in the spring chamber 7 acts on the pilot piston rod 15, the pilot piston 16, the pilot piston rod 15 and the guide plunger 8 move to the left together (these three parts can be integrally constructed or connected to each other after being manufactured separately), and then As the pressure of the pilot control oil port X increases, the displacement of the pilot piston 16 gradually increases, the seal between the pilot piston rod 15 and the pilot valve body 12 opens, and the flow area of the throttle groove on the pilot piston rod 15 increases with the pilot piston. The movement of the rod 15 gradually increases. At this time, the hydraulic oil in the rodless cavity of the hydraulic cylinder acts on the second acting surface A2 of the main valve core from the reverse oil port B through the damping groove 5 (for example, the main valve core shown in Figure 3 The hydraulic oil (oil pressure is P2) on the right end surface) passes through the throttling on the fixed damping hole 9, the communicating oil passage 10, the piston rod matching through hole 20, and the throttle groove sections 142, 143, 144 of the pilot piston rod 15. The groove 145 and the oil drain port L flow back to the oil tank (or the oil return circuit), so the oil pressure P2 of the hydraulic oil acting on the second acting surface A2 of the main valve core decreases. When the oil pressure P2 decreases to a certain extent , the hydraulic oil in the rodless chamber of the hydraulic cylinder (the oil pressure is P1) acts on the first action surface A1 of the main valve core through the reverse oil port B (for example, the main valve core 4 shown in Figure 3 is in the first action chamber 3 After the pressure formed by the pressure end surface inside) is greater than the pressure of the second acting surface A2 of the main spool and the pressure of the main spool spring (that is, P2×A2+Fs, Fs is the force of the main spool spring 6), the main valve The spool moves to the right, and the movement of the main spool will reduce the damping effect of the damping groove 5, so the hydraulic pressure P2 acting on the right end of the main spool increases, and at the same time prevents the main spool from accelerating to the right, making the main valve The movement of the core is relatively stable, and the hydraulic oil flows from the reverse oil port B to the forward oil port A to realize the descending function. When the hydraulic cylinder carries the load and descends too fast, a certain degree of negative pressure is formed in the rod chamber of the hydraulic cylinder, and the pilot control The oil pressure of the oil port X decreases, so the pilot piston rod 15 will move to the right as shown in Figure 3, so that the flow capacity of the throttle groove on the pilot piston rod 15 decreases, and accordingly the flow in the second action chamber The hydraulic oil P2 increases, so that the opening of the main spool 4 is reduced to avoid falling too fast and play a speed limiting role.

On the basis of the above technical solution, the present invention also provides a hydraulic cylinder telescopic control circuit, the hydraulic cylinder telescopic control circuit includes a balance valve and a reversing valve. The valve is connected to one working oil port of the reversing valve, and the rod cavity is connected to the other working oil port of the reversing valve through another working oil circuit. Specifically, the forward oil port A of the balance valve is connected with a working oil port of the reversing valve, the reverse oil port B is connected with the rodless chamber of the hydraulic cylinder, and the pilot control oil port X is connected with the hydraulic cylinder There is a working oil circuit in the rod cavity, and the oil discharge port L is connected with the fuel tank or the oil return circuit. It should be noted here that in the telescopic control circuit of the above-mentioned hydraulic cylinder, the connection of the pilot control oil port X to the working oil circuit of the rod chamber of the hydraulic cylinder is only a typical connection form. In addition, the balance valve of the present invention The pilot hydraulic control oil port X can also be connected to an external hydraulic control oil source outside the telescopic control circuit of the hydraulic cylinder, such as an external hydraulic control oil source formed after the hydraulic oil pumped by the hydraulic pump is decompressed by a pressure reducing valve. The control oil source can be connected to the pilot control oil port X via the corresponding hydraulic control oil circuit, and the corresponding on-off valve or pressure regulating valve can be set on the hydraulic control oil circuit, so that the hydraulic control oil can be supplied to the pilot control oil port X according to the working conditions to realize above control functions. The present invention also provides a hydraulic crane, which includes the above hydraulic cylinder expansion and contraction control circuit.

As can be seen from the above description, the balance valve of the present invention has the advantages of: first, the balance valve of the present invention selectively enables the second action chamber 17 (for example, the second action chamber 17 shown in FIG. The main spool spring chamber 7) of the action chamber communicates with the oil tank or the oil return circuit, so as to control the movement of the main spool 4 by controlling the movement of the pilot piston rod 15, which adopts the pilot control mode, so only the pilot piston rod needs to be controlled The shape and size of 7 can easily obtain a larger control ratio, which makes the descending speed limit control of the balance valve more sensitive, and the opening of the main spool 3 can be effectively controlled through a small control oil pressure, and the main spool The opening of the valve is not greatly affected by the load pressure, but mainly depends on the oil pressure at the pilot control oil port X, so there will be no frequent vibration due to slight changes in the load pressure, and the working stability is good. Second, the second action chamber 17 communicates with the reverse oil port B through the damping groove 5 that can increase the flow capacity and reduce the damping effect as the main valve core moves axially, which can make the balance valve control effect of the present invention more effective Well, a relative dynamic balance is formed between the first action chamber and the second action chamber to avoid excessive opening of the main valve core. Third, in a preferred manner, the pilot piston rod 15 is integrated with a throttle groove 145, and the throttle groove 145 gradually increases with the movement of the pilot piston rod 15 when the pilot control oil port X has sufficient oil pressure. degree, or gradually reduce the opening degree when the oil pressure of the pilot control oil port X decreases, so the working stability is better and the impact phenomenon during the working process is avoided; Fourth, because the pilot control of the balance valve is relatively large, the balance valve The opening of the main spool is mainly controlled by the pilot control oil pressure. At the same time, the length of the throttle groove 145 on the pilot piston rod can be formed longer, so the controllability is better; fifth, because the required control oil pressure is smaller , better energy saving effect. Apparently, since the telescoping control circuit of the hydraulic cylinder and the hydraulic crane of the present invention include the above-mentioned balance valve of the present invention, they also have the above-mentioned technical advantages.

The preferred embodiment of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the specific details of the above embodiment, within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, These simple modifications all belong to the protection scope of the present invention. For example, the main valve body 1 and the pilot valve body 12 can be an integral valve body, and in order to install the main valve core 4, the piston rod 15, etc., the integral valve body can be detachably divided into two structures. In addition, the main valve sleeve 2 can also form an integral structure with the main valve body 1. In this case, the matching structure of the main valve sleeve 2 and the main valve core 3 is directly formed on the main valve body 1. It is slightly difficult to adopt the form of the main valve sleeve 2, but this deformation mode also belongs to the protection scope of the present invention. Generally speaking, the balance valve of the present invention is to propose a more advanced technical solution, and its core technical concept lies in its hydraulic control principle, not in the specific mechanical structure. Under the inspiration of the hydraulic control principle shown in Figure 5 Those skilled in the art can think of various specific valve structures different from those shown in Figure 3, but as long as they adopt the technical concept shown in Figure 5 of the present invention, they should all belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (15)

1. A balance valve, including a main valve body (1) with a forward oil port (A) and a reverse oil port (B) and a main valve core (4) capable of moving in the valve cavity of the main valve body (1) ), the main spool (4) is in the normally closed sealing position where the forward oil port (A) and the reverse oil port (B) are cut off under the elastic pre-tightening force of the main spool spring (6), in, The main spool (4) includes opposite first action surface (A1) and second action surface (A2), and the first action surface (A1) is exposed to the first action surface connected with the reverse oil port (B). In an action cavity (3), the force direction of the second action surface (A2) is the same as the action direction of the elastic pre-tightening force and is exposed to the reverse oil port through the damping groove (5) or damping hole (B) In the connected second action chamber (17), there is an oil drain passage (19) between the second action chamber and the oil drain port (L) of the balance valve; The balance valve also includes a pilot control module, which includes a reciprocatingly movable pilot piston (16) with a pilot piston rod (15), a return spring (14), and a hydraulic control chamber located on one side of the pilot piston (18), the pilot piston rod (15) extends into the drain oil passage (19) and forms a seal with the inner wall of the drain oil passage (19) under the action of the return spring (14) While blocking the oil drain passage, the hydraulic control chamber (18) communicates with the pilot control oil port (X) of the balance valve to receive hydraulic control oil and control the pilot piston (16) to drive the pilot The piston rod (15) moves to make the oil drain passage (19) conduct. the 2. The balance valve according to claim 1, wherein the main spool spring chamber (7) of the main spool spring (6) doubles as the second action chamber (17). the 3. The balance valve according to claim 1, wherein, the second action chamber (17) communicates with the reverse oil port (B) through the damping groove (5), and the damping groove (5) forms On the outer peripheral surface of the main valve core (4), and by cooperating with the inner wall of the valve cavity of the main valve body (1), when the main valve core (4) moves away from the normally closed sealing position During the process, the flow opening of the damping groove (5) is increased. the 4. The balance valve according to claim 3, wherein, on the inner peripheral surface of the valve cavity of the main valve body (1), a protrusion with an axial slope is formed to cooperate with the damping groove (5), the The distance between the protrusion and the bottom wall of the damping groove (5) increases when the main valve core (4) moves away from the normally closed sealing position, so as to increase the flow through the damping groove (5) opening. the 5. The balance valve according to claim 1, wherein the area of the first action surface (A1) is smaller than the area of the second action surface (A2). the 6. The balance valve according to any one of claims 1 to 5, wherein a throttling groove (145) is formed on the pilot piston rod (15), and the flow opening of the throttling groove (145) is Increases as the pilot piston rod (15) moves away from sealing with the inner wall of the drain oil passage (19). the 7. The balance valve according to claim 6, wherein the oil drain passage (19) includes a piston rod fitting through hole (20), and the pilot piston rod (15) extends into the piston rod fitting through hole (20) and under the action of the return spring (14), cooperate with the through hole (20) of the piston rod to form a tapered seal. the 8. The counterbalance valve according to claim 7, wherein said pilot piston rod (15) comprises a throttle groove section (142, 143, 144) whose cross-sectional area continuously decreases so that at said The throttle groove (145) with a continuously increasing cross-sectional area is formed on the pilot piston rod (15), when the pilot piston rod (15) moves away from the position where it is sealed with the piston rod matching through hole (20) , the throttle groove segments (142, 143, 144) move through the piston rod fitting through hole (20) to increase the flow opening of the throttle groove (145). the 9. The balancing valve according to claim 8, wherein the pilot control module comprises a pilot valve body (12) integrally formed with the main valve body (1) or installed on the main valve body (1) , the pilot valve body (12) is formed with a guide plunger chamber (11) and a pilot piston chamber communicated through the piston rod fitting through hole (20), the guide plunger chamber (11) and the second The action chamber (17) is connected, and the pilot piston chamber is provided with the pilot piston (16) that can slide, and is sealed and separated into the return spring chamber (13) and the hydraulic control chamber ( 18), the return spring chamber (13) is provided with the return spring (14), and the wall of the return spring chamber (13) is provided with the oil drain port (L). the 10. The balance valve according to claim 9, wherein one end portion of the pilot piston rod (15) is formed as a conical sealing section (140) that is sealed with the piston rod matching through hole (20), the A connecting oil passage (10) is formed on the conical sealing section (140), and the conical sealing section (140) is connected with a guide plunger (8 ), the guide plunger (8) is provided with a fixed damping hole (9) connecting the communication oil passage (10) and the second action chamber (17), and the oil drain passage (19) is fixed by the The damping hole (9), the connecting oil passage (10), the piston rod matching through hole (20), the throttling groove (145) and the return spring chamber (13) constitute. the 11. The balance valve according to claim 9, wherein one end of the pilot piston rod (15) is provided with a taper fitting (139) that is sealed with the piston rod matching through hole (20), the The taper fitting (139) is located in the pilot plunger cavity (11) and is fixed to the pilot piston rod (15) through a lock nut (138), and the drain oil passage (19) is connected by the The guide plunger cavity (11), the piston rod and the through hole (20), the throttling groove (145) and the return spring cavity (13) are formed. the 12. The balance valve according to claim 9, wherein one end of the pilot piston rod (15) is connected or formed with a ), the sealing column (137) is spaced apart from the inner peripheral surface of the piston rod (137). The guide plunger cavity (11), the piston rod and the through hole (20), the throttling groove (145) and the return spring cavity (13) are formed. the 13. The balance valve according to claim 6, wherein, the main valve body (1) is provided with a main valve sleeve (2), and the valve chamber of the main valve body (1) passes through the main valve sleeve (2). ), the first action chamber (3), the second action chamber (17) and the main valve core spring chamber (7) are formed by the cooperation of the main valve core (3) and the main valve sleeve (2) . the 14. The telescopic control circuit of the hydraulic cylinder, including a balance valve and a reversing valve, wherein the balance valve is the balance valve according to any one of claims 1 to 13, and the positive oil port (A) of the balance valve It communicates with a working oil port of the reversing valve, the reverse oil port (B) communicates with the rodless chamber of the hydraulic cylinder, and the pilot control oil port (X) connects with the working oil circuit of the rod chamber of the hydraulic cylinder or It is connected to an external hydraulic control oil source outside the telescopic control circuit of the hydraulic cylinder, and the oil drain port (L) is connected with the oil tank or the oil return circuit. the 15. A crane, wherein the crane comprises a hydraulic cylinder telescoping control circuit according to claim 14. the

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