Variable motor pressure control valve and design method

Abstract

The application discloses a variable motor pressure control valve and a design method, and the pressure control valve comprises a valve sleeve, a valve core is arranged in the valve sleeve, a first oil port, a second oil port and a control oil port are arranged on the valve sleeve, a step close to the first oil port is arranged on the outer circumferential surface of the valve core, a first through hole is arranged on the valve core in the axial direction, a second through hole communicated with the first through hole is arranged on the valve core in the radial direction, the second through hole is located between the first oil port and the control oil port, a first annular groove communicated with the second oil port is arranged on the outer circumferential surface of the valve core, a second annular groove is arranged between the first annular groove and the second through hole, a third through hole communicated with the first through hole is arranged on the bottom surface of the second annular groove, and the second oil port is communicated with the control oil port through a damping hole. The application has the advantages of low motor failure rate, good replaceability and low improvement cost.

Description

Technical Field

[0001] This invention belongs to the field of variable displacement motors, and particularly relates to a variable displacement motor pressure control valve and its design method. Background Technology

[0002] The output torque of a variable displacement motor (or simply motor) is directly proportional to the product of its displacement and pressure. During motor operation, situations may arise where the load suddenly increases when the motor is at a small displacement. This can lead to: 1) insufficient output torque at the small displacement, and 2) overpressure operation. To address these issues, a pressure control valve is typically added to the motor. The purpose is to: 1) ensure the motor provides sufficient output torque; and 2) protect the motor from overpressure operating conditions. For example, pressure control valves (HD1D, EP2D) are commonly used in conjunction with hydraulic proportional control and electro-proportional control in Rexroth L6VE / M series hydraulic motors.

[0003] The existing pressure control valves (HD1D, EP2D) all have the same structure. Figure 4 As shown, the valve includes a valve sleeve 1, a valve core 2 inside the valve sleeve 1, a first oil port 10, a second oil port 11 and a control oil port 12 on the valve sleeve 1, a step 20 near the first oil port 10 on the outer peripheral surface of the valve core 2, a first through hole 21 in the axial direction of the valve core 2, a second through hole 22 in the radial direction of the valve core 2 communicating with the first through hole 21, the second through hole 22 being located between the first oil port 10 and the control oil port 12, a first annular groove 23 communicating with the second oil port 11 on the outer peripheral surface of the valve core 2, a second annular groove 24 between the first annular groove 23 and the second through hole 22, and a third through hole 25 communicating with the first through hole 21 on the bottom surface of the second annular groove 24.

[0004] like Figure 3 As shown, the first oil port 10 is connected to the working oil port A of the motor through the one-way valve C, the second oil port 11 is connected to the working oil port B of the motor through the one-way valve D, the control oil port 12 is connected to the large end of the variable cylinder of the motor, the first through hole 21 is connected to the return oil port T of the motor, and the outlet end of the one-way valve C is connected in parallel with the outlet end of the one-way valve D.

[0005] During use, it was found that the motor sometimes fails to switch to a smaller displacement, and the motor failure rate is relatively high. Summary of the Invention

[0006] The purpose of this invention is to provide a variable displacement motor pressure control valve and its design method. This invention has the advantages of reducing motor failure rate, good replaceability, and low improvement cost.

[0007] The technical solution of the present invention: A variable displacement motor pressure control valve includes a valve sleeve, a valve core inside the valve sleeve, a first oil port, a second oil port and a control oil port on the valve sleeve, a step near the first oil port on the outer peripheral surface of the valve core, a first through hole in the axial direction of the valve core, a second through hole in the radial direction of the valve core communicating with the first through hole, the second through hole being located between the first oil port and the control oil port, a first annular groove communicating with the second oil port on the outer peripheral surface of the valve core, a second annular groove between the first annular groove and the second through hole, a third through hole communicating with the first through hole on the bottom surface of the second annular groove, and the second oil port communicating with the control oil port through a damping hole.

[0008] The aforementioned design method for the variable motor pressure control valve involves setting a damping orifice between the second annular groove and the first annular groove, allowing the second oil port to connect to the control oil port through the damping orifice.

[0009] Compared with existing technologies, this invention, based on existing pressure control valves (HD1D, EP2D), incorporates a damping orifice that connects to the control port and the second port. Through extensive research, the applicant discovered that the inability of a motor to switch to a smaller displacement typically occurs when the load pressure rises to a certain level and then momentarily drops. In this case, the oil pressure in the control chamber exceeds the load pressure, causing both check valves to close simultaneously. This prevents the high-pressure oil in the control chamber from draining, the valve core from returning to its original position, and the large end of the motor's variable displacement cylinder remains open to return oil, thus preventing a return to a smaller displacement. This invention, by connecting the control port and the second port with the damping orifice, ensures that even with the check valves closed, the high-pressure oil in the control chamber can still drain smoothly, the valve core can return smoothly, and the large end of the motor's variable displacement cylinder is blocked from return oil, allowing the motor to switch to a smaller displacement with a lower failure rate. Furthermore, this invention is an improvement on existing pressure control valves without altering their external dimensions or assembly dimensions. It can directly replace existing pressure control valves, offering good replaceability and very low improvement costs, essentially negligible. Therefore, the present invention has the advantage of reducing motor failure rate, and has good replaceability and low improvement cost. Attached Figure Description

[0010] Figure 1 This is a front view of the present invention.

[0011] Figure 2 yes Figure 1 Enlarged view at point A.

[0012] Figure 3 This is a hydraulic schematic diagram of a pressure control valve on a variable displacement motor.

[0013] Figure 4 This is a front view of an existing pressure control valve.

[0014] The markings in the attached diagram are as follows: 1-valve sleeve, 10-first oil port, 11-second oil port, 12-control oil port; 2-valve core, 20-step, 21-first through hole, 22-second through hole, 23-first annular groove, 24-second annular groove, 25-third through hole. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0016] Example. A variable displacement motor pressure control valve, improved from the HD1D or EP2D type pressure control valve, such as... Figure 1 and Figure 2 As shown, the valve includes a valve sleeve 1, within which a valve core 2 is housed. The valve sleeve 1 has a first oil port 10, a second oil port 11, and a control oil port 12. The outer circumferential surface of the valve core 2 has a step 20 near the first oil port 10. The valve core 2 has a first through hole 21 axially and a second through hole 22 radially communicating with the first through hole 21, located between the first oil port 10 and the control oil port 12. The outer circumferential surface of the valve core 2 has a first annular groove 23 communicating with the second oil port 11. A second annular groove 24 is formed between the first annular groove 23 and the second through hole 22. The bottom surface of the second annular groove 24 has a third through hole 25 communicating with the first through hole 21. The key feature is that the second oil port 11 is connected to the control oil port 12 through a damping hole 3. The damping hole 3 is annular and formed between the valve sleeve 1 and the valve core 2.

[0017] Working principle: First, analyze the existing pressure control valve, such as... Figure 3 As shown, the motor initially operates at a small displacement. When the motor encounters a sudden load change, the system pressure increases. The high-pressure oil in the system acts on step 20 through the one-way valve C(D). At this time, from Figure 3 Looking up, the pressure control valve is in the left position, from Figure 4 Looking upwards, valve core 2 moves to the right, the first through hole 21 connects to the control oil port through the second through hole 22, the large end of the variable cylinder connects to the return oil, and the motor changes to a large displacement. When the load pressure suddenly drops, because there is a very small clearance between valve core 2 and valve sleeve 1, and the one-way valve C closes quickly, the control chamber (the control chamber is...) Figure 2 The oil circuit shown by the double-dotted line is closed, the pressure cannot be reduced, the oil pressure acting on step 20 cannot be reduced, the spring cannot move the valve core 2 back, and the large end of the variable cylinder is still constantly connected to the return oil, which causes the motor to be unable to return to the small displacement.

[0018] After understanding why the motor cannot return to a small displacement, the present invention sets up a damping hole 3 to keep the second oil port 11 and the control oil port 12 open, so that the control chamber will not be closed. Even if the one-way valve C is closed, the oil pressure acting on the step 20 can be reduced, so that the motor can return to a small displacement.

Claims

1. A variable displacement motor pressure control valve, comprising a valve sleeve (1), a valve core (2) disposed inside the valve sleeve (1), a first oil port (10), a second oil port (11) and a control oil port (12) disposed on the valve sleeve (1), a step (20) near the first oil port (10) disposed on the outer peripheral surface of the valve core (2), a first through hole (21) disposed axially on the valve core (2), a second through hole (22) disposed radially on the valve core (2) communicating with the first through hole (21), the second through hole (22) being located between the first oil port (10) and the control oil port (12), a first annular groove (23) communicating with the second oil port (11) disposed on the outer peripheral surface of the valve core (2), a second annular groove (24) disposed between the first annular groove (23) and the second through hole (22), and a third through hole (25) communicating with the first through hole (21) disposed on the bottom surface of the second annular groove (24), characterized in that: A damping hole (3) is provided on the outer circumferential surface of the valve core (2) between the second annular groove (24) and the first annular groove (23). When the first through hole (21) is connected to the control oil port (12) through the second through hole (22), the second oil port (11) is connected to the control oil port (12) through the damping hole (3).

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