A pilot operated proportional displacement control valve

Abstract

The application discloses a pilot proportional displacement control valve, which comprises a valve body, screw plug one, screw plug two, a valve cover, a valve core, piston one, piston two, screw one, pipe joint one, pipe joint two, screw two, screw three, screw plug three, screw plug four, a spring, a pin, an eccentric screw rod, a supporting pin and a push rod. The application utilizes the lever principle and combines machine and liquid, linearly converts the size of the pilot pressure into the displacement size of the push rod ball head, can realize linear proportional control of the displacement of the moving part, and has simple structure and reliable control.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of control valves, in particular to a pilot proportional displacement control valve. BACKGROUND

[0002] Axial piston pump is widely used in the field of engineering machinery, and is a core component of engineering machinery, which plays a crucial role in the performance of the machine. In the process of using the piston pump, in order to change the running speed of the actuator, the size of the pump displacement needs to be changed, and the size of the pump displacement is controlled by the control valve installed on the pump. The control valve on the pump is various, including hydraulic proportional control, two-point control, and electric proportional control. With the increasing demand for informationization and intelligentization in modern society, electric proportional control has gradually become a preferred control method for host manufacturers. The traditional pilot proportional displacement control device is mostly a yoke type, which has a complex yoke shape and needs to be cast. Moreover, the processing difficulty is large. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a pilot proportional displacement control valve, and the specific technical solutions are as follows:

[0004] A pilot proportional displacement control valve, comprising a valve body, a screw plug one, a screw plug two, a valve cover, a valve core, a piston one, a piston two, a screw one, a pipe joint one, a pipe joint two, a screw two, a screw three, a screw plug three, a screw plug four, a spring, a pin, an eccentric screw rod, a support nail and a lever.

[0005] The valve cover is installed on the valve body, the pipe joint one and the pipe joint two are symmetrically installed in the left and right end openings below the valve body through threaded connection, the valve core is located inside the valve body and is installed between the pipe joint one and the pipe joint two, and the end faces of the pipe joint one and the pipe joint two limit the valve core; the piston one and the piston two are symmetrically installed above the valve body inside through the left and right end openings above the valve body, and the left and right end openings above the valve body are sealed by the screw plug one and the screw plug two respectively.

[0006] The screw one is vertically installed in the valve body, the lower end of the screw one is fixedly connected to the middle part of the valve core, and the upper end is located between the piston one and the piston two; the screw one is used for applying the thrust generated by the pilot pressure to the piston one or the piston two; one end of the screw two is fixedly connected to the piston one through the opening in the rear end of the valve body, and one end of the screw three is fixedly connected to the piston two through the opening in the rear end of the valve body; the openings in the rear end of the valve body are sealed by the screw plug three and the screw plug four respectively.

[0007] The two ends of the spring are connected to the screw two and the screw three respectively, and the spring has a certain pre-tightening force when installed.

[0008] The pin is installed in the upper end hole of the lever, the supporting pin is installed in the hole at the middle upper position of the lever, the upper end of the lever is deeply inserted into the valve body, and the eccentric screw is passed through the middle hole of the lever and the two ends of the eccentric screw are supported on the front and rear wall surfaces of the valve body respectively, so that the lever is installed in the valve body; the positions of the upper end hole, the hole at the middle upper position and the middle hole of the lever should meet that when the lever is installed, the pin is located between the piston one and the piston two, and the supporting pin abuts against the valve core, so that the pin limits the left and right direction movement of the piston one and the piston two, and the supporting pin limits the rotation of the valve core.

[0009] Further, a horizontal groove with the same width as the screw two and the screw three is formed on the rear end surface in the valve body, and the other ends of the screw two and the screw three are located in the horizontal groove, so that the screw two and the screw three can only slide left and right along the horizontal groove.

[0010] Further, the surfaces on both sides of the horizontal groove of the valve body are designed as conical surfaces, so that the spring can be more conveniently embedded.

[0011] Further, the spring is a tension spring.

[0012] Further, the piston one and the piston two are mirror installed, so as to ensure the symmetry of bidirectional control of the pilot proportional displacement control valve.

[0013] The beneficial effects of the present application are as follows:

[0014] The present application utilizes the lever principle, combines machine and liquid, linearly converts the size of the pilot pressure into the displacement size of the lever ball head, can realize linear proportional control of the displacement of the moving part, and has simple structure and reliable control. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the appearance view of the pilot proportional displacement control valve of the present embodiment Figure 1 .

[0016] Figure 2 It is the appearance view of the pilot proportional displacement control valve of the present embodiment Figure 2 .

[0017] Figure 3 It is the internal schematic view of the pilot proportional displacement control valve of the present embodiment after removing the valve body.

[0018] Figure 4 It is the main sectional view of the present embodiment.

[0019] Figure 5 It is Figure 4PP sectional view.

[0020] Figure 6 yes Figure 4 FF sectional view.

[0021] Figure 7 This is a schematic diagram of the main internal oil passages of the pilot-operated proportional displacement control valve in this embodiment.

[0022] Figure 8 This is a cross-sectional view of an application example of the pilot-operated proportional displacement control valve of this embodiment being installed on a plunger pump.

[0023] Figure 9 This is a schematic diagram illustrating an application example of the pilot-operated proportional displacement control valve installed on a plunger pump, as described in this embodiment.

[0024] In the diagram, the components are: valve body 1, plug 1 2-1, plug 2 2-2, valve cover 3, valve core 4, piston 1 5-1, piston 2 5-2, screw 1 6, pipe connector 1 8-1, pipe connector 2 8-2, screw 2 9-1, screw 3 9-2, plug 3 10-1, plug 4 10-2, spring 11, pin 12, eccentric screw 13, support pin 14, lever 15, control piston 16, and horizontal groove 101. Detailed Implementation

[0025] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0026] like Figures 1 to 6 As shown, the pilot-operated proportional displacement control valve of this embodiment includes a valve body 1, a first plug 2-1, a second plug 2-2, a valve cover 3, a valve core 4, a first piston 5-1, a second piston 5-2, a first screw 6, a first pipe connector 8-1, a second pipe connector 8-2, a second screw 9-1, a third screw 9-2, a third plug 10-1, a fourth plug 10-2, a spring 11, a pin 12, an eccentric screw 13, a support pin 14, and a lever 15.

[0027] Among them, such as Figure 4 As shown, valve cover 3 is mounted on valve body 1. Pipe connector 1 8-1 and pipe connector 2 8-2 are symmetrically installed in the left and right end openings at the bottom of valve body 1 via threaded connections. Valve core 4 is located inside valve body 1 and is installed between pipe connector 1 8-1 and pipe connector 2 8-2, with the end faces of pipe connector 1 8-1 and pipe connector 2 8-2 limiting the valve core 4. Piston 1 5-1 and piston 2 5-2 are symmetrically installed inside the upper part of valve body 1 through the left and right end openings at the top, and the left and right end openings at the top of valve body 1 are sealed by screw plug 1 2-1 and screw plug 2-2, respectively. Figure 4 andFigure 5 As shown, screw one 6 is vertically installed in valve body 1, and the lower end of screw one 6 is fixedly connected to the middle part of valve core 4, and the upper end is located between piston one 5-1 and piston two 5-2. Screw one 6 is used to apply the pilot pressure connected to the pipe joint to piston one 5-1 or piston two 5-2. In addition, as shown, Figure 5 As shown, one end of screw two 9-1 is fixedly connected to piston one 5-1 through the opening in the rear end of valve body 1, and one end of screw three 9-2 is fixedly connected to piston two 5-2 through the opening in the rear end of valve body 1. As shown, Figure 6 As shown, a horizontal groove 101 with the same width as screw two 9-1 and screw three 9-2 is formed on the rear end surface inside valve body 1, and the other end of screw two 9-1 and screw three 9-2 are both located in horizontal groove 101, so that piston one 5-1 driven by screw two 9-1 and piston two 5-2 driven by screw three 9-2 can only slide left and right along horizontal groove 101. The openings in the rear end of valve body 1 are respectively sealed by screw plug three 10-1 and screw plug four 10-2. As shown, Figure 5 As shown, spring 11 is connected to screw two 9-1 and screw three 9-2 at both ends, and spring 11 has a certain pre-tightening force when installed.

[0028] Spring 11 is a tension spring. The surfaces on both sides of horizontal groove 101 of valve body 1 are designed as tapered surfaces, so that spring 11 can be more conveniently embedded. Piston one 5-1 and piston two 5-2 are mirror image installed, ensuring the symmetry of bidirectional control of the pilot proportional displacement control valve.

[0029] As shown, Figure 6 As shown, pin 12 is installed in the upper end hole of lever 15, support pin 14 is installed in the hole at the middle upper position of lever 15, the upper end of lever 15 penetrates into valve body 1, and eccentric screw 13 penetrates through the middle hole of lever 15, and the two ends of eccentric screw 13 are respectively supported on the front and rear wall surfaces of valve body 1, so as to realize the installation of lever 15 in valve body 1. The positions of the upper end hole, the hole at the middle upper position and the middle hole of lever 15 should satisfy that when lever 15 is installed, pin 12 is located between piston one 5-1 and piston two 5-2, and support pin 14 abuts against valve core 4, so as to realize the left and right direction movement limiting of piston one 5-1 and piston two 5-2 by pin 12, and the rotation limiting of valve core 4 by support pin 14.

[0030] The installation process of the entire pilot proportional displacement control valve is as follows:

[0031] Firstly, the valve core 4 is installed into the valve body 1, then the screw 6 is screwed into the threaded hole of the valve core 4, then the pin 12 is pressed into the upper end hole of the lever 15, the support pin 14 is screwed into the hole of the lever 15 in the upper position, then the middle plane of the valve core 4 is rotated to be parallel to the side surface of the valve body 1, at the same time, the lever 15 is passed through the middle of the valve core 4 and the valve body 1, until the middle hole of the lever 15 is aligned with the installation hole of the valve body 1, at this time, the support pin 14 installed on the lever 15 will contact with the middle plane of the valve core 4, the freedom of rotation of the valve core 4 is limited, then the eccentric screw 13 is passed through the installation hole of the other side surface of the valve body 1, through the through hole below the lever 15, through the installation hole of the side surface of the valve body 1, at this time, the installation of the eccentric screw 13 is completed, then the piston 5-1 and the piston 5-2 are installed into the valve body, then the screw plug 2-1 and the screw plug 2-2 are screwed into the valve body 1, then the pipe joint 8-1 and the pipe joint 8-2 are installed, then the screw 9-1 and the screw 9-2 are screwed into the threaded holes of the piston 5-1 and the piston 5-2 through the installation holes of the screw plug 3 10-1 and the screw plug 4 10-2 on the valve body 1, then the screw plug 3 10-1 and the screw plug 4 10-2 are screwed onto the valve body 1, then the spring 11 is assembled onto the recess between the screw plug 3 10-1 and the screw plug 4 10-2, finally, the valve cover 3 is installed onto the valve body 1, the entire pilot proportional displacement control valve is assembled.

[0032] The operating principle of the entire pilot proportional displacement control valve is as follows:

[0033] As Figure 7 and Figure 8As shown, when this pilot-operated proportional displacement control valve is installed on a plunger pump, the lower ball end of the lever 15 is mounted on the control piston 16 of the plunger pump. This electro-proportional displacement control valve can symmetrically and bidirectionally control the swashplate angle of the plunger pump, keeping it at a certain angle between -β and β. This depends on whether the external pilot pressure is supplied through the Ps1 port of pipe connector 1-8-1 or the Ps2 port of pipe connector 2-8-2, and the magnitude of the pilot pressure. The control logic is bidirectionally symmetrical. When an external pilot pressure is supplied to port Ps1 of pipe connector 1 8-1 or port Ps2 of pipe connector 2 8-2, valve core 4 will be subjected to a thrust proportional to the magnitude of the external pilot pressure. At the same time, the pilot-operated proportional displacement control valve opens, and pressurized oil will enter pump control chamber a or b, pushing control piston 16 to move. As control piston 16 moves, it also rotates lever 15. When lever 15 rotates, piston 1 5-1 or piston 2 5-2 will stretch spring 11 under the action of pin 12. When the extension of spring 11 causes the spring force to increase slightly beyond the thrust applied to valve core by the pilot pressure, valve core 4 will be pulled back to the neutral position by piston 1 5-1 or piston 2 5-2. At this time, since the pressurized oil entering pump control chambers a and b is only used to compensate for leakage, control piston 16 will stop moving. The distance that control piston 16 moves is directly proportional to the magnitude of the pilot pressure of the pilot-operated proportional displacement control valve, thereby realizing that the displacement of the plunger pump changes linearly with the magnitude of the pilot pressure.

[0034] The principle of this pilot-operated proportional displacement control valve will be explained below by introducing external pilot pressure into the Ps1 port of pipe connector 1 8-1. The situation of introducing external pilot pressure into the Ps2 port of pipe connector 2 8-2 can also be understood.

[0035] like Figures 7 to 9 As shown, in the initial state, the spring 11 is in the initial pre-tension position with a certain preload. The magnitude of the preload determines the starting point of the control current of the pilot-operated proportional displacement control valve. Due to machining and assembly errors, the eccentric screw 13 is first adjusted so that the valve core 4 is in the neutral position. At this time, the function of the pilot-operated proportional displacement control valve is the PTab interconnection state with a very small opening. The control piston 16 of the plunger pump, along with the swashplate, is in the position of zero swing angle, and the plunger pump has no output flow.

[0036] When the Ps1 port is connected with the external pilot pressure, the Ps2 port is connected with the T port, at this time, the pilot pressure acts on the left end face of the valve core 4, and pushes the valve core 4 to the right for a distance, and the distance is limited by the end face of the pipe joint 8-2, at the same time, the screw 6 above the valve core 4 will drive the piston 5-2 to move to the right, but at this time, the pressure oil of the P port has not entered the control cavity a of the plunger pump, so the control piston 16 still stays in the middle position, which means that the shift lever 15 and the pin 12 remain stationary, and then the piston 5-1 cannot move to the right due to the limitation of the pin 12, and the spring 11 is elongated, at this time, the function of the pilot proportional displacement control valve is that the P-a is fully open and the b-T is fully open, the pressure oil of the P port enters the a cavity of the plunger pump through the pilot proportional displacement control valve, and the oil in the b cavity of the plunger pump flows out through the T port, the control piston 16 moves to the right under the action of the hydraulic pressure, in the process of the control piston 16 moving to the right, the shift lever 15 is counterclockwise rotated, and then the piston 5-1 is driven to move to the left through the pin 12 on the shift lever 15, and the spring 11 is further elongated, and the spring force is increased, when the control piston 16 moves to the right for a distance, the spring force is slightly greater than the hydraulic pressure exerted on the valve core 4 by the external pilot pressure connected with the Ps1 port, at this time, the piston 5-2 is moved to the left by the piston 5-1 through the spring 11, and the valve core 4 is also moved to the left by the screw 6 in contact with the piston 5-2, the control piston 16 moves to the right for a small distance, and pulls the valve core 4 back to the original position, at this time, the function of the control valve is that the P-T-a-b is interchanged with a small opening degree, and the control piston 16 stays at this position, since the control piston 16 is connected with the swash plate of the plunger pump, the swash plate will also swing to an angle, and the plunger pump will output a certain displacement; the pushing force exerted on the valve core 4 by the external pilot pressure connected with the Ps1 port is determined by the size of the external pilot pressure, the greater the pilot pressure, the greater the pushing force, and then the control piston 16 needs to move a longer distance to increase the spring force more, so as to pull the valve core 4 back to the original position, that is, the displacement of the control piston is determined by the size of the external pilot pressure, the greater the external pilot pressure, the greater the displacement of the piston, and the greater the swing angle of the swash plate of the plunger pump, and the greater the displacement output by the plunger pump, so as to realize the proportional control of the displacement of the plunger pump by the size of the pilot pressure.

[0037] When the external pilot pressure of Ps1 port is unloaded, the hydraulic pressure of the pilot pressure applied to the left end face of the spool 4 disappears, but at this time the control piston 16 is not yet moved, and the piston one 5-1 cannot move either, which means that the piston two 5-2 will be pulled by the spring 11 to move leftward, and the spool 4 will move leftward with it until the end face of the pipe joint one 8-1 limits, at which time the function of the pilot proportional displacement control valve is P-b full open and a-T full open, and the pressure oil of the P port enters the b cavity of the plunger pump through the pilot proportional displacement control valve, and the oil of the a cavity of the plunger pump will flow out through the T port of the pilot proportional displacement control valve, and the control piston 16 moves leftward under the action of the hydraulic pressure of the b cavity, and the shift rod 15 rotates clockwise, and the piston one 5-1 moves rightward under the pulling force of the spring 11, at which time the spool 4 remains stationary due to the end face limitation of the pipe joint one 8-1, and the pilot proportional displacement control valve is still in the full open state, and the b cavity continues to admit oil, and the control piston 16 continues to move leftward, until the control piston one 5-1 contacts the screw one 6, and the control piston two 5-2 contacts the pin 12, at which time the spring 11 will return to the initial pre-stretching state, and the control piston 16 continues to move leftward for a small distance, and the spool 4, the piston one 5-1 and two 5-2, the screw one 6, and the spring 11 return to the initial position together, and the function of the pilot proportional displacement control valve is gradually from P-b full open and a-T full open to the initial opening degree of P-T-a-b intercommunication state, and the control piston returns to the initial position and stops moving, at which time the swash plate angle is zero, and the plunger pump stops outputting oil.

[0038] Those skilled in the art can understand that the above description is only a preferred example of the application and is not used to limit the application, although the application is described in detail with reference to the foregoing examples, and those skilled in the art can still modify the technical solutions recorded in the foregoing examples or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A pilot operated proportional displacement control valve characterized by, The valve body (1), the screw plug (2-1), the screw plug (2-2), the valve cover (3), the valve core (4), the piston (5-1), the piston (5-2), the screw (6), the pipe joint (8-1), the pipe joint (8-2), the screw (9-1), the screw (9-2), the screw plug (10-1), the screw plug (10-2), the spring (11), the pin (12), the eccentric screw (13), the support pin (14) and the push rod (15) are included. The valve cover (3) is installed on the valve body (1), the pipe joint (8-1) and the pipe joint (8-2) are symmetrically installed in the left and right end holes below the valve body (1) through threaded connection, the valve core (4) is located inside the valve body (1) and is installed between the pipe joint (8-1) and the pipe joint (8-2), and the end faces of the pipe joint (8-1) and the pipe joint (8-2) limit the valve core (4); the piston (5-1) and the piston (5-2) are symmetrically installed above the valve body (1) through the left and right end holes above the valve body (1), and the left and right end holes above the valve body (1) are sealed by the screw plug (2-1) and the screw plug (2-2) respectively. The screw (6) is vertically installed in the valve body (1), the lower end of the screw (6) is fixedly connected to the middle part of the valve core (4), and the upper end is located between the piston (5-1) and the piston (5-2); the screw (6) is used for applying the thrust generated by the pilot pressure to the piston (5-1) or the piston (5-2); one end of the screw (9-1) is fixedly connected to the piston (5-1) through the hole in the rear end of the valve body (1), and one end of the screw (9-2) is fixedly connected to the piston (5-2) through the hole in the rear end of the valve body (1); the holes in the rear end of the valve body (1) are sealed by the screw plug (10-1) and the screw plug (10-2) respectively. The two ends of the spring (11) are connected to the screw (9-1) and the screw (9-2) respectively, and the spring (11) has a certain pre-tightening force when being installed. The pin (12) is installed in the upper end hole of the lever (15), the supporting pin (14) is installed in the hole at the middle upper position of the lever (15), the upper end of the lever (15) is deeply inserted into the valve body (1), and the eccentric screw (13) passes through the middle hole of the lever (15) and is supported on the front and rear wall surfaces of the valve body (1) at both ends, so that the lever (15) is installed in the valve body (1); the positions of the upper end hole, the hole at the middle upper position and the middle hole of the lever (15) satisfy that when the lever (15) is installed, the pin (12) is located between the piston one (5-1) and the piston two (5-2), and the supporting pin (14) abuts against the valve core (4), so that the pin (12) limits the left and right direction movement of the piston one (5-1) and the piston two (5-2), and the supporting pin (14) limits the rotation of the valve core (4).

2. The pilot operated proportional displacement control valve of claim 1, wherein, The rear end surface inside the valve body (1) is provided with a horizontal groove (101) with the same width as the screw two (9-1) and the screw three (9-2), and the other ends of the screw two (9-1) and the screw three (9-2) are located in the horizontal groove (101), so that the screw two (9-1) drives the piston one (5-1) and the screw three (9-2) drives the piston two (5-2) can only slide left and right along the horizontal groove (101).

3. The pilot operated proportional displacement control valve of claim 2 wherein, The two side surfaces of the horizontal groove (101) of the valve body (1) are designed as conical surfaces, so that the spring (11) can be more conveniently embedded.

4. The pilot operated proportional displacement control valve of claim 3 wherein, The spring (11) is a tension spring.

5. The pilot operated proportional displacement control valve of claim 4 wherein, The piston one (5-1) and the piston two (5-2) are mirror installed to ensure the symmetry of the bidirectional control of the pilot proportional displacement control valve.

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