CN105952705B - Balanced valve - Google Patents

Abstract

The invention relates to a balance valve, which is characterized in that it comprises a valve body, which is provided with a first oil port, a second oil port, and a control oil port; a balance valve sleeve; a balance valve core installed in the balance valve sleeve, There is a stepped through hole inside the balance spool, and the balance spool divides the control chamber in the balance valve sleeve into two independent front chambers and rear chambers; the pilot spool installed in the stepped through hole of the balance spool, the pilot spool Supported by the first spring to keep moving forward, the front end of the pilot spool is located in the small diameter part of the stepped through hole, the rear end of the pilot spool is located in the large diameter part of the stepped through hole, and the rear end of the pilot spool is equipped with a second Three damping holes, a throttling groove is opened on the outer peripheral wall of the front end of the pilot spool; when the pilot spool moves forward. The utility model is a balance valve with simple and reasonable structure, which can stably control the opening of the balance valve core, is free from load interference, and allows relatively large installation torque.

Description

balance valve

technical field

The invention relates to a hydraulic valve, in particular to a hydraulic balance valve capable of maintaining a stable lowering of a load.

Background technique

In modern engineering machinery, construction machinery and other mechanical equipment, a large number of lifting hydraulic circuits are used. In the boom extension and retraction systems of concrete pump trucks, balance valves are usually used for hydraulic locking to ensure that the boom can be positioned at any position. Reliable stay. Among them, the balance valve is the key hydraulic component of the load control system and the hydraulic bearing system, and the performance of the balance valve directly affects the operation quality of the main engine. With the increasing difficulty of concrete pump truck operation, the requirements for sealing, self-locking, stability and multi-functionality of the balance valve are getting higher and higher, and the power density of the balance valve itself is also increasing. With the continuous refresh of the working height, the working pressure of the boom system of the pump truck is also rising. In this context, how to improve the safe operation performance of the concrete pump truck boom system has become the focus of research.

Figure 10 shows a common load control hydraulic system using balancing valves used in the boom system of a concrete pump truck. Its working principle is: when the reversing valve 3' is switched to the load lowering position, the A port of the reversing valve 3' will output oil, and the oil will enter the rod cavity Y of the boom cylinder, and part of the oil will pass through the Px port and damping Hole 1' enters the hydraulic control chamber (piston chamber) Pil of the balance valve, thereby opening the balance valve 2', and the oil in the rodless chamber W passes through the C port and V port of the balance valve 2' and the B port of the reversing valve 3 to return When the reversing valve 3 is switched to the load-rising working position, oil is discharged from the B port, and the oil passes through the check valve in the balance valve 2' (the main structure of the balance valve generally includes a parallel overflow Flow valve and one-way valve, as shown in Figure 4) enter the rodless chamber W of the oil cylinder, the oil in the rod chamber Y returns to the oil tank T through the A of the reversing valve 3', and the weight G rises. When the reversing valve 3' is not switched, the balance valve 2' is closed to seal the oil in the port C and the rodless cavity W of the oil cylinder, and keep the weight G at the required position. The hydraulic system in Figure 4 has various deficiencies and drawbacks. For example, when it is adjusted to the fast operation gear, the pressure and flow of the hydraulic oil on the main oil circuit through the Px port will increase rapidly, and when the balance valve 2' is opened, it will cause a pressure shock to the conventional pilot control valve part of the balance valve. This shock may Cause the balance valve to open suddenly, causing the equipment to work unstable. In addition, the control pressure range of the balance valve in Figure 4 is narrow, the pressure and flow fluctuate greatly, and the micro-control and stability of the balance valve opening process are poor. This control pressure fluctuation and control flow fluctuation of the balance valve will cause the opening of the balance valve 2' to change, making it difficult to keep the position of the piston in the boom cylinder at an accurate position. Therefore, the balance valve installed on the very long boom cylinder is prone to an unstable situation, causing uncontrollability of the equipment and making the equipment work in an unsafe state.

A kind of balancing valve is disclosed in the invention patent entitled "balance valve" as authorized notification number CN103104565B. But there are multiple deficiencies and defects in this balancing valve.

1. The pilot spool of the balance valve in this invention is a steel ball. In the control of the small opening of the balance valve, very precise pilot pressure control is required to realize the slow change of the flow rate to avoid the sudden opening impact of the balance valve. This is difficult to implement in general hydraulic systems.

2. The opening of the main valve core of the balance valve is determined by the load pressure and the control pressure. Therefore, the change of the load pressure will cause the change of the opening of the main valve core, which will cause the change of the flow rate and cause the main engine to shake.

3. The pilot control stage only has a decompression circuit composed of 2 dampers. When the control pressure at the X port fluctuates greatly due to load changes, it cannot play a good buffering role, which will cause the opening of the balance valve spool to change, resulting in hydraulic pressure. Cylinder vibration, which can cause severe vibration of the main engine on long-arm operating equipment such as aerial work vehicles or concrete pump trucks, seriously affecting operation safety and operation accuracy. In the decompression circuit composed of the pilot control stage, a part of the oil directly flows back to the oil tank. In the large flow system, the oil return has not much influence, but in the small flow system or the pilot composed of accumulators In the handle control circuit, the flow loss of this part flowing back to the fuel tank is very large, which seriously limits the application of this invention.

4. The valve sleeve is an integral structure. When the coaxiality of the insertion hole is poorly processed and the installation torque is too large, the valve sleeve will be deformed, causing the balance valve spool and the control piston to be stuck, reducing the reliability of use.

Contents of the invention

The technical problem to be solved by the present invention is to provide a balance valve with a simple and reasonable structure, which can stably control the opening of the balance valve core, is free from load interference, and allows relatively large installation torque.

The technical solution adopted by the present invention to solve the above technical problems is: a balance valve, which is characterized in that: it includes a valve body with a spool cavity, and the first oil port and the second oil port communicated with each other are opened on the valve body. There is also a control oil port on the body, the first oil port and the second oil port are located on the side wall of the valve body, and the control oil port is located at the front end of the valve body; the balance valve sleeve is installed in the spool cavity of the valve body to balance There is a sealing ring between the outer circumference of the valve sleeve and the inner wall of the valve core cavity, and the balance valve sleeve is provided with an inlet connecting the second oil port and the control chamber of the balance valve sleeve. The first valve port, the first cross-sectional area of the control chamber of the balance valve sleeve is larger than the second cross-sectional area of the first valve port; the balance valve core installed in the balance valve sleeve and can slide relative to the axial direction, the balance valve core There is a stepped through hole inside. The balance valve core separates the control chamber in the balance valve sleeve into two independent parts: the front chamber and the rear chamber. The second oil port is connected to the rear chamber through the fourth damping hole on the side wall of the balance valve sleeve. Connected, the front end of the balance spool extends into the first valve port, the rear end of the balance spool matches the inner wall of the balance valve sleeve, and the rear end and front end of the balance spool are connected by the first taper surface, the first The cone surface is used to block the first valve port; when the balance spool moves forward, the first cone surface contacts the first valve port, blocking the communication between the first oil port and the second oil port through the first valve port. When the balance spool moves backward, the first taper surface leaves the first valve port, and the first oil port communicates with the second oil port through the first valve port; it is installed in the stepped through hole of the balance spool and can slide relative to the axial direction. The pilot spool is moved forward. The pilot spool is supported by the first spring to keep moving forward. The outer periphery of the pilot spool has a second tapered surface that matches the small diameter part of the stepped through hole. The second tapered surface is used to block the stepped through hole. The small aperture part of the hole, the front end of the pilot spool is located in the small aperture part of the stepped through hole, the rear end of the pilot spool is located in the large diameter part of the stepped through hole, and the rear end of the pilot spool is provided with a connection between the back chamber and the ladder. The third damping hole in the small diameter part of the through hole, the outer peripheral wall of the front end of the pilot spool is provided with a throttling groove whose flow area gradually increases from back to front; when the pilot spool moves forward, the second The tapered surface is in contact with the small diameter portion of the stepped through hole, blocking the communication between the rear chamber and the first oil port after passing through the third damping hole and the small diameter portion of the stepped through hole. After passing through the third damping hole, the throttle groove and the small diameter part of the stepped through hole, it communicates with the first oil port; the pilot control part is used to make the pressure oil passing through the control oil port push the pilot spool to move.

As an improvement, the outer periphery of the front end of the above-mentioned balance valve core is provided with a connecting flow passage for communicating the second oil port with the first oil port via the first valve port. In this way, when the balance spool moves backward, the second oil port communicates with the first oil port through the connecting flow passage, controlling the flow rate through the first valve port to ensure more stable work.

In order to facilitate the installation of the first spring, a first spring seat is provided in the rear cavity, and the first spring is held between the rear end of the pilot valve core and the first spring seat.

As a further improvement, the valve body is composed of a valve housing and a connecting sleeve that is floatingly connected to the rear end of the valve housing through a buckle structure. The valve body forms a floating connection structure, and the valve housing and the connecting sleeve are floatingly connected through the buckle structure, so that in the case of large installation torque or poor coaxiality of the insertion hole processing, the deformation of the connecting sleeve will not be transmitted to the balance The valve sleeve, the pilot spool and the following control piston improve the reliability of the balance valve.

In order to facilitate the setting of the third damping hole, the rear end of the above-mentioned pilot valve core is provided with a second connecting channel for communicating with the small aperture part of the rear cavity and the stepped through hole, and the second connecting channel is internally threaded with a third damping block. The third damping hole is arranged on the third damping block.

As a further improvement, the above-mentioned pilot control part includes a piston chamber located at the rear end of the valve body. The front end of the valve body is fixed with an end cover that seals the piston chamber. The end cover has a liquid outlet channel that communicates with the outside world and the piston chamber. The channel communicates with the piston chamber through the second valve port, and the control oil port is arranged on the end cover; the first damping hole is arranged in the control oil port, and the first damping hole communicates with the outside world and the piston chamber; the one-way valve core, It is installed in the liquid outlet channel and can slide axially relative to the liquid outlet channel. The one-way valve core is supported by the second spring to keep the tendency to block the second valve port; it is installed in the piston chamber and can be axially opposite to the piston chamber. There is a sealing ring between the head of the control piston and the inner hole wall of the piston cavity. The head of the control piston divides the piston cavity into two parts: the rod cavity and the rodless cavity. There is a second damping hole for connecting the rod chamber and the rodless chamber, the rod part of the control piston passes through the top wall of the rod chamber to push the pilot spool, the rod part of the control piston and the top wall of the rod chamber There is a sealing ring between the walls of the inner hole to block the communication between the rod cavity and the valve core cavity of the valve body; the third spring is set in the rod cavity and acts on the head of the control piston to keep the control piston facing Tendency to move axially in the direction of the end cap.

The advantages of the aforementioned pilot control section are:

1) When the oil pressure px entering the pilot control valve from the control oil port suddenly rises, the oil enters the rodless chamber of the piston chamber from the first damping hole first, and the rise of pressure p1 in the rodless chamber pushes the control piston to move to the right ; When the oil pressure px entering the pilot control valve from the control oil port suddenly rises, the rightward movement of the control piston must discharge the oil in the rod chamber to the rodless chamber through the second damping hole, so that the control piston can continue to move to the right , due to the existence of the second damping hole, when the control piston moves to the right, the pressure p2 in the rod cavity is greater than the pressure p1 in the rodless cavity, and the pressure p2 in the rod cavity prevents the control piston from moving to the right, realizing buffering; only When the control pressure px continues to rise, the control piston can continue to move to the right, which plays a role in filtering the control pressure fluctuations. Similarly, when the oil pressure px entering the pilot control valve from the control oil port drops, the pressure p2 in the rod chamber and the pressure p1 in the rodless chamber drop at the same time (p1=p2 in the equilibrium state), and the pressure in the rod chamber The drop of p2 reduces the rightward resistance overcome by the pressure p1 in the rodless cavity, and plays a role of buffering and controlling the leftward movement of the piston.

2), and because the balance valve does not need too much buffer when it is about to close, through the cooperation of the one-way valve core and the second spring, the pressure p1 in the rodless cavity and the control pressure px can be controlled when a certain pressure difference is reached. The pressure p1 in the rodless cavity is quickly opened through the one-way valve core, and the pressure is discharged directly after passing through the liquid outlet channel, without going through the first damping hole, and finally realizes the rapid closing of the balance valve. The advantages of the aforementioned pilot control section are:

In order to facilitate the setting of the first damping hole, the control oil port of the above-mentioned end cover is internally threaded with a first damping block, and the first damping hole is arranged on the first damping block.

In order to facilitate the setting of the second damping hole, the above-mentioned control piston is provided with a second connecting channel connecting the rod chamber and the rodless chamber, and the second connecting channel is internally threaded with a second damping block, and the second damping hole is set at the second Two damping blocks.

In order to facilitate the assembly of the one-way valve core, a second spring seat is provided in the liquid outlet channel of the above-mentioned end cover, and the second spring is supported between the second spring seat and the one-way valve core.

As a further improvement, the above-mentioned end cap has a threaded connection column inserted and screwed into the piston cavity, and the rear end surface of the threaded connection column has an annular wall extending toward the control piston, and the annular wall is used to contact the head of the control piston. . Because the protruding part extends into the piston chamber, the length of the control piston can be shortened, which can ensure that the tail of the control piston can extend into the large-diameter part, saving costs. If there is no threaded connection column, the tail of the control piston must be ensured Only when the piston cavity is extended can it enter the large-diameter part. In addition, the setting of the annular wall ensures that even if the control piston head is in contact with the annular wall of the end cover, there is a certain space in the rodless cavity.

Compared with the prior art, the present invention has the advantages of:

1. The front peripheral wall of the pilot spool is provided with a throttling groove whose flow area becomes larger gradually from the back to the front to realize the gradual change of the flow rate. In this way, the flow rate will change slowly and will not cause sudden changes at the moment of micro-action or opening. open shock;

2. The opening amount of the balance spool is controlled by the opening amount of the pilot spool. When the pilot spool opens for a certain distance, the oil in the second oil port B reaches the rear cavity through the fourth damping hole, and then passes through the third damping hole. , The throttle groove of the pilot spool flows into the first oil port A, so there is a certain pressure difference between the pressure pB of the second oil port and the pressure p3 in the rear chamber, and the pressure pB of the second oil port>in the rear chamber The pressure p3 of the second oil port acts on the annular area A12 formed by A1 and A2 of the balance spool, and the pressure p3 in the rear chamber acts on the first cross-sectional area A1 of the balance spool, so that when the pilot When the spool is opened to a certain distance, pB*A12>pB*A1, the balance spool is moved to the right by the resultant force; but as soon as the balance spool moves to the right, the opening of the pilot spool decreases again (throttle groove effect), and p3 rises again , until pb*A34=Pb*A3. The third damping hole on the pilot spool has a pressure compensation function within a certain pressure range, which can ensure the flow stability of the balance valve. It is based on this follow-up principle that the opening of the balance spool is not affected by the load pressure, but is only determined by the movement of the pilot spool, so it will not cause flow fluctuations and vibrations due to load changes.

3. The valve body is in the form of floating connection, which will not cause the valve core to be stuck due to excessive installation torque or insufficient machining accuracy of the valve hole, which improves reliability.

Description of drawings

Fig. 1 is a structural sectional view of an embodiment of the present invention;

Fig. 2 is a cross-sectional view of a balance valve sleeve in an embodiment of the present invention;

Fig. 3 is the front view of the balanced spool in the embodiment of the present invention;

Fig. 4 is the side view of balance spool in the embodiment of the present invention;

Fig. 5 is the front view of pilot spool in the embodiment of the present invention;

Fig. 6 is a side view of the pilot valve core in the embodiment of the present invention;

Fig. 7 is a structural cross-sectional view of the pilot control part in the embodiment of the present invention;

Fig. 8 is a schematic diagram of the principle of the pilot control part in the embodiment of the present invention;

Fig. 9 is a schematic diagram of the application principle of the embodiment of the present invention;

Fig. 10 is a common load control hydraulic system using balance valves in the boom system of the existing concrete pump truck.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figures 1-9, it is a preferred embodiment of the present invention.

A balancing valve comprising

A valve body 1 with a spool chamber, the valve body 1 is opened with a first oil port A and a second oil port B communicating with each other, the valve body 1 is also opened with a control oil port X, the first oil port A and the second oil port The oil port B is located on the side wall of the valve body, and the control oil port X is located at the front end of the valve body 1. The valve body 1 is composed of a valve housing 12 and a connecting sleeve 14 floatingly connected to the rear end of the valve housing 12 through a buckle structure 13 .

The balance valve sleeve 2 is installed in the spool cavity of the valve body 1. A sealing ring is provided between the outer periphery of the balance valve sleeve 2 and the inner wall of the valve core cavity. The inlet 21 of the control cavity of 2, the front part of the control cavity of the balance valve sleeve 2 has an annular inner shoulder blade 22 to form the first valve port 4a, and the first cross-sectional area A1 of the control cavity of the balance valve sleeve 2 is larger than the first valve port 4a The second cross-sectional area A2.

The balance valve core 3 installed in the balance valve sleeve 2 and can slide relative to the axial direction. The balance valve core 3 has a stepped through hole inside, and the balance valve core 3 divides the control chamber in the balance valve sleeve 2 into an independent front chamber 5a and the rear cavity 5b, the second oil port B communicates with the rear cavity 5b through the fourth damping hole 7d on the side wall of the balance valve sleeve 2, the front end 31 of the balance valve core 3 extends into the first valve port 4a, and the balance valve core The rear end 32 of 3 is matched with the inner cavity wall of the balance valve sleeve 2, and the rear end 32 and the front end 31 of the balance valve core 3 are connected by the first tapered surface 33, which is used to block the first valve Mouth 4a. The outer periphery of the front end 31 of the balance valve core 3 is provided with a connecting channel 311 for communicating the second oil port B with the first oil port A via the first valve port 4a.

When the balance spool 3 moves forward, the first taper surface 33 contacts the first valve port 4a, blocking the communication between the first oil port A and the second oil port B through the first valve port 4a. After the balance spool 3 In the shifted state, the first tapered surface 33 leaves the first valve port 4a, and the first oil port A communicates with the second oil port B through the first valve port 4a.

The pilot spool 8 is installed in the stepped through hole of the balance spool 3 and can slide relative to the axial direction. The pilot spool 8 is supported by the first spring 10a to keep moving forward, and the rear chamber 5b is provided with a first spring seat. 11a, the first spring 10a is supported between the rear end of the pilot valve core and the first spring seat 11a. The outer circumference of the pilot spool 8 has a second tapered surface 81 that matches the small aperture portion 34 of the stepped through hole. The second tapered surface 81 is used to block the small aperture portion 34 of the stepped through hole. In the small aperture portion 34 of the hole, the rear end of the pilot spool 8 is located in the large diameter portion 35 of the stepped through hole, and the rear end of the pilot spool 8 is provided with a small aperture portion 34 for communicating with the rear chamber 5b and the stepped through hole The third damping hole 7c, the outer peripheral wall of the front end of the pilot valve core 8 is provided with a throttling groove 82 whose flow area gradually increases from the rear to the front, and the throttling groove 82 is triangular in shape.

When the pilot spool 8 moves forward, the second tapered surface 81 is in contact with the small diameter portion 34 of the stepped through hole, blocking the connection between the rear cavity 5b and the first through the third damping hole 7c and the small diameter portion 34 of the stepped through hole. The communication of oil port A, when the pilot spool 8 moves backward, the rear chamber 5b communicates with the first oil port A after passing through the third damping hole 7c, the throttling groove 82 and the small diameter portion 34 of the stepped through hole in sequence. The rear end of the pilot spool 8 is provided with a second connecting channel 83 for connecting the rear cavity 5b and the small aperture portion 34 of the stepped through hole. The second connecting channel 83 is internally threaded with a third damping block 73, and the third The damping hole 7c is provided on the third damping block 73 .

The pilot control part is used to make the pressure oil passing through the control oil port X push the pilot spool 8 to move.

The pilot control section includes

The piston cavity 15 located at the inner rear end of the valve body 1, the front end of the valve body 1 is fixed with an end cover 6 that blocks the piston cavity 15, and the end cover 6 has a liquid outlet channel 61 that communicates with the outside world and the piston cavity 15. The liquid passage 61 communicates with the piston chamber 15 through the second valve port 4b, and the control oil port X is arranged on the end cover 6 .

The first damping hole 7 a is arranged in the control oil port X, and the first damping hole 7 a communicates with the outside world and the piston chamber 15 . The control oil port X of the end cover 6 is internally threaded with a first damping block 71 , and the first damping hole 7 a is disposed on the first damping block 71 .

The one-way valve core 16 is arranged in the liquid outlet channel 61 and can slide axially relative to the liquid outlet channel 61. The one-way valve core 16 is supported by the second spring 10b to keep blocking the second valve port 4b The trend; the liquid outlet channel 61 of the end cover 6 is provided with a second spring seat 11b, and the second spring 10b is supported between the second spring seat 11b and the one-way valve core 16.

The control piston 9 which is arranged in the piston cavity 15 and can slide axially relative to the piston cavity 15 is provided with a sealing ring between the head 91 of the control piston 9 and the inner hole wall of the piston cavity 15, and the head of the control piston 9 91 divides the piston chamber 15 into two parts, the rod chamber 151 and the rodless chamber 152. The control piston 9 is provided with a second damping hole 7b for communicating with the rod chamber 151 and the rodless chamber 152. The rod part 92 of the control piston 9 Pass through the top wall of the rod chamber 151 to push the pilot spool 8, and a sealing ring is arranged between the rod part 92 of the control piston 9 and the inner hole wall of the rod chamber 151 to block the rod. The chamber 151 communicates with the valve core chamber of the valve body 1; the end cover 6 has a threaded connection post 63 inserted and threaded into the piston chamber 15, and the rear end surface of the threaded connection post 63 has an annular ring extending toward the control piston 9. The wall 62, the annular wall 62, is intended to be in contact with the head 91 of the control piston. The control piston 9 is provided with a second connecting passage 93 communicating with the rod chamber 151 and the rodless chamber 152, the second connecting passage 93 is internally threaded with the second damping block 72, and the second damping hole 7b is arranged in the second damping hole 7b. on block 72.

The third spring 10c is arranged in the rod cavity 151 and acts on the head 91 of the control piston 9 to keep the control piston 9 moving axially towards the end cover 6 .

The working principle and process of the balance valve are divided into three processes: rising, stopping and falling, as shown in Figure 9.

During the rising process, the pressure oil of the reversing valve reaches the first oil port A of the balance valve, and the pressure oil of the first oil port A pushes the balance spool 12 to open (at this time, the pilot spool 8 is closed), and the first oil passes through A The flow into the second oil port B reaches the rodless chamber of the hydraulic cylinder, pushing the hydraulic cylinder upward.

During the descending process, the pressure oil at the control oil port X pushes the control piston 15 to move to the right, causing the pilot spool 8 to have a certain displacement, and the hydraulic cylinder slowly descends from the static state; the pressure at the control oil port X continues to increase, and the opening of the pilot spool 8 continues. increase, the hydraulic cylinder speed continues to increase; when the displacement of the pilot spool 8 continues to increase to a certain stage at the control oil port X pressure, the balance spool 3 opens, and the opening amount of the balance spool 3 is controlled by the opening amount of the pilot spool 8 Yes, when the pilot spool 8 is opened for a certain distance, the oil in the second oil port B reaches the rear cavity 5b through the fourth damping hole 7d, and then flows into the first port through the third damping hole 7c and the throttle groove 82 of the pilot spool. Oil port A, so there is a certain pressure difference between the pressure pB of the second oil port and the pressure p3 in the rear cavity, the pressure pB of the second oil port> the pressure p3 in the rear cavity, and the pressure pB of the second oil port acts On the annular area A12 formed by A1 and A2 of the balance spool, the pressure p3 in the rear cavity acts on the first cross-sectional area A1 of the balance spool, so that when the pilot spool opens to a certain distance, pB*A12> pB*A1, the balance spool is moved to the right by the resultant force; but as soon as the balance spool 3 moves to the right, the opening of the pilot spool 8 decreases again (the throttle groove 82 acts), and p3 rises again until pb*A34=Pb*A3 . The third damping hole 7c on the pilot spool has a pressure compensation function within a certain pressure range, which can ensure the flow stability of the balance valve. Due to the setting of the throttling groove 82, the flow rate is gradually changed, so that at the moment of micro-action or opening, the flow rate changes slowly, and no sudden opening impact will be caused. The opening of the balance spool 3 can be controlled by controlling the pressure of the oil port X, thereby controlling the speed of the oil cylinder descending. It is based on this follow-up principle that the opening of the balance spool is not affected by the load pressure, but is only determined by the movement of the pilot spool, so it will not cause flow fluctuations and vibrations due to load changes.

Stopping the process, the pressure of the control oil port x decreases, the displacement of the pilot spool 8 decreases, the area of the throttle groove 82 formed between the pilot spool 8 and the balance spool 3 decreases, the pressure at the rear end of the balance main spool 3 increases, and the balance The spool 3 moves forward; the pressure drop of the control oil port x is 0, the first spring 10a pushes the pilot spool 8 forward, and the second conical surface 71 is used to block the small diameter portion 34 of the stepped through hole, thus balancing the spool 3 Under the action of the pressure of the second oil port B, it also moves forward to realize closing.

The working principle and process of the pilot control valve are as follows:

1. When the pilot spool of the balance valve reaches a balanced and stable state, the oil pressure px entering the pilot control valve from the control oil port X = the pressure p1 in the rodless chamber 152 = the pressure p2 in the rod chamber 151, and the pressure in the balance valve The opening of the pilot spool 8 is stable, and the position of the control piston 5 is fixed.

2. When the oil pressure px entering the pilot control valve from the control oil port X suddenly rises, the oil first enters the rodless chamber 151 of the piston chamber through the first damping hole 7a, and the rise of the pressure p1 in the rodless chamber 151 pushes the control The piston 9 moves to the right; when the oil pressure px entering the pilot control valve from the control oil port 62 suddenly rises, the right movement of the control piston 9 must discharge the oil in the rod chamber 152 to the rodless chamber through the second damping hole 7b 151, the control piston 9 can continue to move to the right, because of the existence of the second damping hole 7b, when the control piston 9 moves to the right, the pressure p2 in the rod chamber 152 is greater than the pressure p1 in the rodless chamber 151, and the pressure in the rod chamber 152 p2 prevents the control piston 9 from moving to the right and realizes buffering; only when the control pressure px continues to rise, the control piston 9 can continue to move to the right, which plays a role in filtering the control pressure fluctuations. Similarly, when the oil pressure px entering the pilot control valve from the control oil port X drops, the pressure p2 in the rod chamber 152 and the pressure p1 in the rodless chamber 151 drop simultaneously (p1=p2 in the equilibrium state), and the rod The drop of the pressure p2 in the cavity 152 reduces the rightward resistance overcome by the pressure p1 in the rodless cavity 151, and plays a role of buffering the leftward movement of the control piston 9.

3. Since the balance valve does not need too much buffer when it is about to close, through the cooperation of the one-way valve core 16 and the second spring 10b, the pressure p1 and the control pressure px in the rodless cavity 151 can be controlled until a certain pressure difference is reached. At this time, the pressure p1 in the rodless cavity 151 is quickly opened through the one-way valve core 16, and the pressure is discharged directly after passing through the liquid outlet channel 61, without going through the first damping hole 7a, and finally realizes the rapid closing of the balance valve.

Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations of the present invention will occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A kind of 1. balanced valve, it is characterised in that：Including

   Valve body (1) with spool chamber, is provided with the first hydraulic fluid port (A) to communicate with each other, the second hydraulic fluid port (B), valve body on valve body (1) (1) control port (X) is also provided with, first hydraulic fluid port (A) and the second hydraulic fluid port (B) are located on body wall, control port (X) Then it is located at valve body (1) front end；

   Valve pocket (2) is balanced, in the spool chamber of valve body (1), is balanced between valve pocket (2) periphery and spool cavity wall equipped with close Seal, balances the import (21) for the control chamber that the second hydraulic fluid port of connection (B) and balance valve pocket (2) are provided with valve pocket (2), balances valve pocket (2) there is omoplate (22) in annular to form the first valve port (4a) for the front portion of control chamber, balance the first of the control chamber of valve pocket (2) Cross-sectional area (A1) is more than the second cross-sectional area (A2) of the first valve port (4a)；

   Installed in the balance valve core (3) that balance valve pocket (2) is interior and can slide to axial, there is ladder inside balance valve core (3) The control chamber balanced in valve pocket (2) is separated into independent ante-chamber (5a) and back cavity (5b) two parts by through hole, balance valve core (3), Second hydraulic fluid port (B) is connected by balancing the 4th damping hole (7d) on valve pocket (2) side wall with back cavity (5b), balance valve core (3) The first valve port (4a) is stretched into front end (31), and the rear end (32) of balance valve core (3) coordinates with the internal chamber wall of balance valve pocket (2), balance It is connected between the rear end (32) and front end (31) of spool (3) by first conical surface (33), first conical surface (33) is blocking the One valve port (4a)；

   Before balance valve core (3) under shifting state, first conical surface (33) contacts with the first valve port (4a), blocks the first hydraulic fluid port (A) connected by the first valve port (4a) with the second hydraulic fluid port (B), under balance valve core (3) afterwards shifting state, first conical surface (33) The first valve port (4a) is left, the first hydraulic fluid port (A) is connected by the first valve port (4a) with the second hydraulic fluid port (B)；

   In the ladder hole of balance valve core (3) and the pilot valve (8) that can slide to axial, pilot valve (8) by First spring (10a) holds the reach trend that keeps, and pilot valve (8) periphery has to be coordinated with the small-bore portion (34) of ladder hole Second conical surface (81), second conical surface (81) is to block the small-bore portion (34) of ladder hole, the front end position of pilot valve (8) In the small-bore portion (34) of ladder hole, the rear end of pilot valve (8) is located in the heavy caliber portion (35) of ladder hole, guide In the rear end of spool (8) be equipped with to connect back cavity (5b) and ladder hole small-bore portion (34) the 3rd damping hole (7c), The throttling channel (82) become larger by rear to preceding flow area is provided with the front end periphery wall of the pilot valve (8)；

   Before pilot valve (8) under shifting state, second conical surface (81) is contacted with the small-bore portion (34) of ladder hole, blocks back cavity (5b) via the connection with the first hydraulic fluid port (A) afterwards of the small-bore portion (34) of the 3rd damping hole (7c) and ladder hole, in pilot valve Core (8) is afterwards under shifting state, and back cavity (5b) is successively via the small-bore portion of the 3rd damping hole (7c), throttling channel (82) and ladder hole (34) connected afterwards with the first hydraulic fluid port (A)；

   Pilot control part, to make the pressure oil by control port (X) promote pilot valve (8) mobile.
2. 2. balanced valve according to claim 1, it is characterised in that：Front end (31) periphery of the balance valve core (3) is provided with To make the linking runner (311) that the second hydraulic fluid port (B) is communicated via the first valve port (4a) with the first hydraulic fluid port (A).
3. 3. balanced valve according to claim 1, it is characterised in that：The first spring base (11a) is equipped with the back cavity (5b), First spring (10a) is held between the rear end of pilot valve and the first spring base (11a).
4. 4. balanced valve according to claim 1, it is characterised in that：The valve body (1) is by valve casing (12) and passes through buckle structure (13) connector sleeve (14) of the floating connection in valve casing (12) rear end forms.
5. 5. balanced valve according to claim 1, it is characterised in that：It is equipped with the rear end of the pilot valve (8) to connect Second interface channel (83) in the small-bore portion (34) of back cavity (5b) and ladder hole, the connection of the second interface channel (83) internal thread There is the 3rd damping block (73), the 3rd damping hole (7c) is arranged on the 3rd damping block (73).
6. 6. according to the balanced valve described in Claims 1 to 5 any claim, it is characterised in that：The pilot control part bag Include

   Arranged on the plunger shaft (15) of valve body (1) Internal back end, valve body (1) is fixedly arranged at the front end with the end cap for blocking plunger shaft (15) (6), there is the liquid outlet channel (61) for connecting extraneous and described plunger shaft (15), liquid outlet channel (61) passes through second in end cap (6) Valve port (4b) is connected with plunger shaft (15), and the control port (X) is arranged on end cap (6)；

   First damping hole (7a), is arranged in control port (X), the first damping hole (7a) connection external world and plunger shaft (15)；

   Nonreturn valve core (16), and can be with respect to liquid outlet channel (61) axial slip, the check valve in the liquid outlet channel (61) Core (16) is held by second spring (10b) to keep blocking the trend of the second valve port (4b)；

   In the plunger shaft (15) and can opposing pistons chamber (15) axial slip control piston (9), the head of control piston (9) (91) it is equipped with sealing ring between the inner hole wall of plunger shaft (15) to seal, the head (91) of control piston (9) is by plunger shaft (15) It is divided into rod chamber (151) and rodless cavity (152) two parts, is equipped with control piston (9) to connect rod chamber (151) and without bar The second damping hole (7b) of chamber (152), the bar portion (92) of control piston (9) are pierced by the roof of rod chamber (151) to promote Pilot valve (8) is stated, it is close that sealing ring is equipped between the bar portion (92) of control piston (9) and the roof inner hole wall of rod chamber (151) Envelope, to block rod chamber (151) and the spool chamber of valve body (1) to connect；

   3rd spring (10c), in the rod chamber (151) and acts on the heads (91) of control piston (9) and makes control piston (9) Keep the trend towards the axial movement of end cap (6) direction.
7. 7. balanced valve according to claim 6, it is characterised in that：Control port (X) internal thread of the end cap (6) is connected with First damping block (71), first damping hole (7a) are arranged on the first damping block (71).
8. 8. balanced valve according to claim 6, it is characterised in that：Connection rod chamber (151) is equipped with the control piston (9) With the second interface channel (93) of rodless cavity (152), the second interface channel (93) internal thread is connected with the second damping block (72), institute The second damping hole (7b) is stated to be arranged on the second damping block (72).
9. 9. balanced valve according to claim 6, it is characterised in that：Second is equipped with the liquid outlet channel (61) of the end cap (6) Spring base (11b), the second spring (10b) are held between second spring seat (11b) and nonreturn valve core (16).
10. 10. balanced valve according to claim 6, it is characterised in that：The end cap (6), which has, is inserted into and is threaded in piston Threaded connection column portion (63) in chamber (15), is threadedly coupled to have on the rear end face of column portion (63) and prolongs to control piston (9) direction The annular wall (62) stretched, annular wall (62) contact to the head (91) with control piston.