Pilot-operated type proportional displacement control valve

Abstract

The pilot-operated type proportional displacement control valve comprises a valve body, a first plug, a second plug, a valve deck, a valve element, a first piston, a second piston, a first screw, a first pipe connector, a second pipe connector, a second screw, a third screw, a third plug, a fourth plug, a spring, a pin, an eccentric screw rod, a supporting nail and a shifting rod. By means of the lever principle and mechanical-hydraulic combination, pilot pressure is linearly converted into displacement of the driving lever ball head, linear proportional control over displacement of moving parts can be achieved, the structure is simple, and control is reliable.

Description

Technical Field

[0001] The invention relates to the field of control valves, and in particular to a pilot-operated proportional displacement control valve. Background Art

[0002] Axial piston pumps are widely used in the field of engineering machinery. They are the core components of engineering machinery and play a vital role in the performance of the machine. During the use of the piston pump, in order to change the operating speed of the actuator, it is necessary to change the size of the pump displacement, and the size of the pump displacement is controlled by the control valve installed on the pump. There are various control valves on the pump, including hydraulic proportional control, two-point control, electric proportional control, etc. As modern society has higher and higher requirements for informatization and intelligence, electric proportional control has gradually become a control method favored by host manufacturers. Traditional pilot-type proportional displacement control devices are mostly fork-type, in which the fork has a complex shape, needs to be cast, and is difficult to process. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention proposes a pilot-operated proportional displacement control valve, and the specific technical solution is as follows:

[0004] A pilot-operated proportional displacement control valve comprises a valve body, a screw plug 1, a screw plug 2, a valve cover, a valve core, a piston 1, a piston 2, a screw 1, a pipe joint 1, a pipe joint 2, a screw 2, a screw 3, a screw plug 3, a screw plug 4, a spring, a pin, an eccentric screw, a support pin and a lever;

[0005] The valve cover is installed on the valve body, and the pipe joint 1 and the pipe joint 2 are symmetrically installed in the left and right openings at the bottom of the valve body through threaded connection. The valve core is located inside the valve body and installed between the pipe joint 1 and the pipe joint 2, and the end faces of the pipe joint 1 and the pipe joint 2 limit the position of the valve core; the piston 1 and the piston 2 are symmetrically installed above the inside of the valve body through the left and right openings above the valve body, and the left and right openings above the valve body are sealed by the screw plug 1 and the screw plug 2 respectively;

[0006] The screw 1 is vertically installed in the valve body, and the lower end of the screw 1 is fixedly connected to the middle part of the valve core, and the upper end is located between the piston 1 and the piston 2; the screw 1 is used to apply the thrust generated by the pilot pressure to the piston 1 or the piston 2; one end of the screw 2 passes through the opening at the rear end of the valve body and is fixedly connected to the piston 1, and one end of the screw 3 passes through the opening at the rear end of the valve body and is fixedly connected to the piston 2; the opening at the rear end of the valve body is sealed by the screw plug 3 and the screw plug 4 respectively;

[0007] The two ends of the spring are respectively connected to the second screw and the third screw, and a certain pre-tightening force exists when the spring is installed;

[0008] The pin is installed in the upper end hole of the shift rod, and the supporting pin is installed in the hole in the middle and upper position of the shift rod. The upper end of the shift rod penetrates into the valve body, and the eccentric screw passes through the middle hole of the shift rod, and the two ends of the eccentric screw are respectively supported on the front and rear wall surfaces of the valve body, thereby realizing the installation of the shift rod in the valve body; the positions of the upper end hole, the hole in the middle and upper position, and the middle hole of the shift rod must meet the following requirements: when the shift rod is installed, the pin is located between the piston one and the piston two, and the supporting pin abuts against the valve core, thereby realizing that the pin limits the left and right movement of the piston one and the piston two, and the supporting pin limits the rotation of the valve core.

[0009] Furthermore, a horizontal groove with the same width as screw 2 and screw 3 is provided on the rear end surface inside the valve body, and the other ends of screw 2 and screw 3 are both located in the horizontal groove, limiting the screw 2 to drive piston 1 and the screw 3 to drive piston 2 to slide left and right along the horizontal groove.

[0010] Furthermore, the two side surfaces of the horizontal groove of the valve body adopt a conical surface design, so that the spring can be embedded more conveniently.

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

[0012] Furthermore, the first piston and the second piston are installed in a mirror image to ensure the symmetry of the bidirectional control of the pilot-operated proportional displacement control valve.

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

[0014] The present invention utilizes the lever principle and the combination of machine and fluid to linearly convert the size of the pilot pressure into the size of the displacement of the lever ball head, thereby realizing linear proportional control of the displacement of the moving parts, and has a simple structure and reliable control. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The appearance of the pilot-operated proportional displacement control valve of this embodiment is shown in FIG. Figure 1 .

[0016] Figure 2 The appearance of the pilot-operated proportional displacement control valve of this embodiment is shown in FIG. Figure 2 .

[0017] Figure 3 This is a schematic diagram of the interior of the pilot-operated proportional displacement control valve of this embodiment with the valve body removed.

[0018] Figure 4 It is a main sectional view of this embodiment.

[0019] Figure 5 yes Figure 4PP cross-sectional view.

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

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

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

[0023] Fig. 9 It is a schematic diagram of an application example in which the pilot-operated proportional displacement control valve of this embodiment is installed on a plunger pump.

[0024] In the figure, valve body 1, screw plug 1 2-1, screw plug 2-2, valve cover 3, valve core 4, piston 1 5-1, piston 2 5-2, screw 1 6, pipe joint 1 8-1, pipe joint 2 8-2, screw 2 9-1, screw 3 9-2, screw plug 3 10-1, screw plug 4 10-2, spring 11, pin 12, eccentric screw 13, support pin 14, lever 15, control piston 16, horizontal groove 101. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below based on the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more clear. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used 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 screw plug 2-1, a screw plug 2-2, a valve cover 3, a valve core 4, a piston 5-1, a piston 5-2, a screw 6, a pipe joint 8-1, a pipe joint 8-2, a screw 2 9-1, a screw 3 9-2, a screw plug 3 10-1, a screw plug 4 10-2, a spring 11, a pin 12, an eccentric screw 13, a support pin 14 and a shift rod 15.

[0027] Among them, Figure 4 As shown, the valve cover 3 is installed on the valve body 1, and the pipe joint 1 8-1 and the pipe joint 2 8-2 are symmetrically installed in the left and right openings at the bottom of the valve body 1 through threaded connection. The valve core 4 is located inside the valve body 1 and installed between the pipe joint 1 8-1 and the pipe joint 2 8-2. The end faces of the pipe joint 1 8-1 and the pipe joint 2 8-2 limit the valve core 4. The piston 1 5-1 and the piston 2 5-2 are symmetrically installed above the inside of the valve body 1 through the left and right openings at the top of the valve body 1, and the left and right openings at the top of the valve body 1 are sealed by the screw plug 1 2-1 and the screw plug 2-2 respectively. Figure 4 and Figure 5 As shown, screw 1 6 is vertically installed in valve body 1, and the lower end of screw 1 6 is fixedly connected to the middle of valve core 4, and the upper end is located between piston 1 5-1 and piston 2 5-2. Screw 1 6 is used to apply the pilot pressure of the external pipe joint to piston 1 5-1 or piston 2 5-2. In addition, as Figure 5 As shown, one end of the screw 2 9-1 passes through the opening at the rear end of the valve body 1 and is fixedly connected to the piston 1 5-1, and one end of the screw 3 9-2 passes through the opening at the rear end of the valve body 1 and is fixedly connected to the piston 2 5-2. Figure 6 As shown, a horizontal groove 101 with the same width as screw 2 9-1 and screw 3 9-2 is provided on the rear end surface of the valve body 1, and the other ends of screw 2 9-1 and screw 3 9-2 are both located in the horizontal groove 101, limiting the screw 2 9-1 to drive piston 1 5-1 and screw 3 9-2 to drive piston 2 5-2 to slide left and right along the horizontal groove 101. The opening at the rear end of the valve body 1 is sealed by screw plug 3 10-1 and screw plug 4 10-2 respectively. Figure 5 As shown, the two ends of the spring 11 are respectively connected to the second screw 9-1 and the third screw 9-2, and there is a certain pre-tightening force when the spring 11 is installed.

[0028] The spring 11 is a tension spring. The two side surfaces of the horizontal groove 101 of the valve body 1 are designed with conical surfaces, so that the spring 11 can be more conveniently embedded. The piston 1 5-1 and the piston 2 5-2 are installed in a mirror image to ensure the symmetry of the two-way control of the pilot-operated proportional displacement control valve.

[0029] like Figure 6 As shown, the pin 12 is installed in the upper hole of the lever 15, and the support pin 14 is installed in the hole at the upper middle position of the lever 15. The upper end of the lever 15 penetrates into the valve body 1, and passes through the middle hole of the lever 15 through the eccentric screw 13, and the two ends of the eccentric screw 13 are respectively supported on the front and rear walls of the valve body 1, so that the lever 15 is installed in the valve body 1. The positions of the upper hole, the hole at the upper middle position and the middle hole of the lever 15 must meet the following requirements: when the lever 15 is installed, the pin 12 is located between the piston 1 5-1 and the piston 2 5-2, and the support pin 14 abuts against the valve core 4, so that the pin 12 is used to limit the left and right movement of the piston 1 5-1 and the piston 2 5-2, and the support pin 14 is used to limit the rotation of the valve core 4.

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

[0031] First, install the valve core 4 into the valve body 1, then screw the screw 6 into the threaded hole of the valve core 4, then press the pin 12 into the upper end hole of the lever 15, screw the support nail 14 into the hole in the upper middle position of the lever 15, then rotate the plane in the middle of the valve core 4 to be parallel to the side of the valve body 1, and at the same time pass the lever 15 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 mounting hole of the valve body 1. At this time, the support nail 14 installed on the lever 15 will contact the plane in the middle of the valve core 4, limiting the freedom of rotation of the valve core 4, and then pass the eccentric screw 13 through the mounting hole on the other side of the valve body 1, through the through hole under the lever 15, and through the mounting hole on the side of the valve body 1. At this time After the eccentric screw 13 is installed, the piston 1 5-1 and the piston 2 5-2 are then installed into the valve body, and then the screw plug 1 2-1 and the screw plug 2-2 are screwed into the valve body 1, and the pipe joint 1 8-1 and the pipe joint 2 8-2 are installed. Then the screw 2 9-1 and the screw 3 9-2 are respectively passed through the mounting holes of the screw plug 3 10-1 and the screw plug 4 10-2 on the valve body 1 and screwed into the threaded holes on the piston 1 5-1 and the piston 2 5-2. Then the screw plug 3 10-1 and the screw plug 4 10-2 are screwed onto the valve body 1, and then the spring 11 is assembled to the groove between the screw plug 3 10-1 and the screw plug 4 10-2. Finally, the valve cover 3 is installed on the valve body 1, and the entire pilot proportional displacement control valve is assembled.

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

[0033] like Figure 7 and Figure 8As shown, when the pilot-operated proportional displacement control valve is installed on the plunger pump, the lower end ball head of the lever 15 is installed on the control piston 16 of the plunger pump. The electric proportional displacement control valve can symmetrically control the swash plate angle of the plunger pump in both directions, so that it stays at a certain angle between -β and β, which depends on whether the external pilot pressure is passed through the Ps1 port of the pipe joint 1 8-1 or the Ps2 port of the pipe joint 2 8-2 and the size of the pilot pressure. The control logic is bidirectionally symmetrical. When the external pilot pressure is introduced into the Ps1 port of the pipe connector 1 8-1 or the Ps2 port of the pipe connector 2 8-2, the valve core 4 will be subjected to a thrust proportional to the external pilot pressure. At the same time, the pilot proportional displacement control valve will open, and the pump control chamber a or b will enter the pressure oil to push the control piston 16 to move. The control piston 16 moves and the lever 15 rotates. When the lever 15 rotates, the piston 1 5-1 or the piston 2 5-2 will stretch the spring 11 driven by the pin 12. When the elongation of the spring 11 causes the spring force to increase to slightly exceed the thrust applied to the valve core by the pilot pressure, the valve core 4 will be pulled back to the middle position by the piston 1 5-1 or the piston 2 5-2. At this time, since the pressure oil entering the pump control chambers a and b is only used to compensate for leakage, the control piston 16 will stop moving. The distance the control piston 16 moves is in direct proportion to the pilot pressure of the pilot proportional displacement control valve, thereby realizing that the displacement of the plunger pump changes linearly with the pilot pressure.

[0034] The principle of the pilot-operated proportional displacement control valve is explained below by taking the Ps1 port of pipe connector 1 8-1 as an example to introduce an external pilot pressure, and the situation where the Ps2 port of pipe connector 2 8-2 is introduced as an example to introduce an external pilot pressure can also be understood.

[0035] like Figures 7 to 9 As shown, in the initial state, the spring 11 is in the initial pre-stretched position with a certain pre-tightening force. The magnitude of the pre-tightening force determines the starting point of the control current of the pilot proportional displacement control valve. Due to processing and assembly errors, the eccentric screw 13 is first adjusted to make the valve core 4 in the middle position. At this time, the function of the pilot proportional displacement control valve is the PTab intercommunication state with a very small opening. The control piston 16 of the plunger pump is in the zero swing angle position with the swash plate, and the plunger pump has no output flow.

[0036] When the external pilot pressure is introduced into the Ps1 port, the Ps2 port is connected to the T port. At this time, the pilot pressure acts on the left end face of the valve core 4, pushing the valve core 4 to the right for a distance, and this distance is limited by the end face of the pipe joint 8-2. At the same time, the screw 16 on the valve core 4 will drive the piston 2 5-2 to move to the right. However, the pressure oil at the P port has not entered the control chamber a of the plunger pump at this time, so the control piston 16 still stays in the middle position, which means that the lever 15 and the pin 12 remain stationary. Then, due to the limit of the pin 12, the piston 5-1 will not be able to move to the right, and the spring 11 will be stretched. At this time, the pilot pressure The functions of the pilot-operated proportional displacement control valve are Pa fully open and bT fully open. The pressure oil in the P port enters the a chamber of the plunger pump through the pilot-operated proportional displacement control valve. The oil in the b chamber of the plunger pump will flow out through the T port through the pilot-operated proportional displacement control valve. The control piston 16 moves to the right under the push of the hydraulic pressure. In the process of the control piston 16 moving to the right, it will drive the lever 15 to rotate counterclockwise, and then drive the piston 15-1 to the left through the pin 12 on the lever 15. The spring 11 is further stretched and the spring force increases. When the control piston 16 moves a certain distance to the right, the spring force Increase to a level slightly larger than the hydraulic pressure exerted on the valve core 4 by the external pilot pressure entering the Ps1 port. At this time, the piston 2 5-2 will be pulled to the left by the piston 1 5-1 through the spring 11. The valve core 4 will also be moved to the left by the screw 1 6 in contact with the piston 2 5-2. The control piston 16 moves a short distance to the right, pulling the valve core 4 back to the left. At this time, the function of the control valve is the PTab interconnection with a very small opening. The control piston 16 will stay in this position. Since the control piston 16 is connected to 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 thrust exerted on the valve core 4 by the external pilot pressure introduced into the Ps1 port is determined by the size of the external pilot pressure introduced. The greater the pilot pressure, the greater the thrust, and the control piston 16 needs to move a longer distance to increase the spring force more before the valve core 4 can be pulled back to its original position. In other words, 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 piston displacement, the greater the swing angle of the plunger pump swash plate, and the greater the displacement output by the plunger pump, which realizes the control of the size of the plunger pump displacement by the ratio of the pilot pressure.

[0037] When the external pilot pressure at the Ps1 port is released, the liquid pressure applied by the pilot pressure on the left end face of the valve core 4 disappears, but the control piston 16 has not moved at this time, and the piston 15-1 cannot move. This means that the piston 2 5-2 will be pulled to the left by the spring 11, and at the same time, the valve core 4 will move to the left until it is restricted by the end face of the pipe joint 18-1. At this time, the functions of the pilot proportional displacement control valve are Pb fully open and aT fully open. The pressure oil in the P port enters the b chamber of the plunger pump through the pilot proportional displacement control valve, and the oil in the a chamber of the plunger pump will flow out through the T port of the pilot proportional displacement control valve. The control piston 16 moves to the left under the action of the liquid pressure in the b chamber, and the lever 15 rotates clockwise, and the piston 15-1 moves to the right under the pulling force of the spring 11. At this time, the valve core 4 remains stationary due to the end face limit of the pipe joint 8-1, the pilot proportional displacement control valve is still in the fully open state, the b chamber continues to enter oil, and the control piston 16 continues to move to the left until the control piston 5-1 contacts the screw 6 and the control piston 5-2 contacts the pin 12. At this time, the spring 11 will return to the initial pre-stretched state, and the control piston 16 will continue to move to the left for a short distance, bringing the valve core 4, pistons 5-1 and 5-2, screws 6 and spring 11 back to the initial position. The function of the pilot proportional displacement control valve is to gradually return from the fully open state of Pb and the fully open state of aT to the interconnected state of PTab with a very small initial opening. The control piston returns to the initial position and stops moving. At this time, the swash plate angle returns to zero, and the plunger pump stops outputting oil.

[0038] Those skilled in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the invention shall be included in the protection scope of the invention.

Claims

1. A pilot-operated proportional displacement control valve, characterized in that: It comprises a valve body (1), a screw plug 1 (2-1), a screw plug 2 (2-2), a valve cover (3), a valve core (4), a piston 1 (5-1), a piston 2 (5-2), a screw 1 (6), a pipe joint 1 (8-1), a pipe joint 2 (8-2), a screw 2 (9-1), a screw 3 (9-2), a screw plug 3 (10-1), a screw plug 4 (10-2), a spring (11), a pin (12), an eccentric screw (13), a support pin (14) and a lever (15); The valve cover (3) is mounted on the valve body (1); the pipe joint 1 (8-1) and the pipe joint 2 (8-2) are symmetrically mounted in the left and right openings at the bottom of the valve body (1) through threaded connection; the valve core (4) is located inside the valve body (1) and is mounted between the pipe joint 1 (8-1) and the pipe joint 2 (8-2); the valve core (4) is limited by the end faces of the pipe joint 1 (8-1) and the pipe joint 2 (8-2); the piston 1 (5-1) and the piston 2 (5-2) are symmetrically mounted above the inside of the valve body (1) through the left and right openings at the top of the valve body (1); and the left and right openings at the top of the valve body (1) are sealed by the screw plug 1 (2-1) and the screw plug 2 (2-2) respectively; The screw one (6) is vertically installed in the valve body (1), and the lower end of the screw one (6) is fixedly connected to the middle part of the valve core (4), and the upper end is located between the piston one (5-1) and the piston two (5-2); the screw one (6) is used to apply the thrust generated by the pilot pressure to the piston one (5-1) or the piston two (5-2); one end of the screw two (9-1) passes through the opening at the rear end of the valve body (1) and is fixedly connected to the piston one (5-1), and one end of the screw three (9-2) passes through the opening at the rear end of the valve body (1) and is fixedly connected to the piston two (5-2); the opening at the rear end of the valve body (1) is sealed by the screw plug three (10-1) and the screw plug four (10-2) respectively; The two ends of the spring (11) are respectively connected to the second screw (9-1) and the third screw (9-2), and a certain pre-tightening force exists when the spring (11) is installed; The pin (12) is installed in the upper end hole of the lever (15), and the support pin (14) is installed in the hole at the upper middle position of the lever (15). The upper end of the lever (15) penetrates into the valve body (1), and the eccentric screw (13) passes through the middle hole of the lever (15), and the two ends of the eccentric screw (13) are respectively supported on the front and rear walls of the valve body (1), so that the lever (15) is installed in the valve body (1); The positions of the upper end hole, the hole at the upper middle position and the middle hole of the lever (15) must satisfy the following conditions: 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 support pin (14) abuts against the valve core (4), so that the pin (12) limits the left-right movement of the piston one (5-1) and the piston two (5-2), and the support pin (14) limits the rotation of the valve core (4).

2. The pilot operated proportional displacement control valve according to claim 1, characterized in that: A horizontal groove (101) having the same width as the second screw (9-1) and the third screw (9-2) is provided on the rear end surface inside the valve body (1), and the other ends of the second screw (9-1) and the third screw (9-2) are both located in the horizontal groove (101), so that the second screw (9-1) drives the first piston (5-1), and the third screw (9-2) drives the second piston (5-2) to slide left and right along the horizontal groove (101).

3. The pilot operated proportional displacement control valve according to claim 2, characterized in that: The surfaces on both sides of the horizontal groove (101) of the valve body (1) are designed with conical surfaces, so that the spring (11) can be more conveniently embedded.

4. The pilot operated proportional displacement control valve according to claim 3, characterized in that: The spring (11) is a tension spring.

5. The pilot operated proportional displacement control valve according to claim 4, characterized in that: The piston one (5-1) and the piston two (5-2) are installed in a mirror image to ensure the symmetry of the bidirectional control of the pilot-operated proportional displacement control valve.

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