Integrated oil supplementing one-way relief valve for closed hydraulic piston variable displacement pump

Abstract

The application discloses an integrated oil supplementing one-way overflow valve for a closed hydraulic plunger variable pump, which comprises a valve sleeve, a large valve core arranged in the valve sleeve, a small valve core arranged in the large valve core, a first spring arranged on the large valve core, and a second spring arranged on the small valve core; one end of the valve sleeve is provided with a first inlet and outlet, and the side wall of the valve sleeve is provided with a second inlet and outlet; the large valve core and the valve sleeve form a first on-off port; the large valve core and the small valve core form a second on-off port, one side of the second on-off port is communicated with the first inlet and outlet, and the other side of the second on-off port is communicated with the second inlet and outlet; and the application further comprises a control oil channel with at least three ports. The application has the functions of integrating a one-way oil supplementing valve and a high-pressure overflow valve, is suitable for two kinds of oil circuits, namely a pilot type and a direct-acting type, improves the end cover compatibility, and reduces the manufacturing cost of the end cover of the closed hydraulic plunger variable pump.

Description

Technical Field

[0001] This invention belongs to the field of closed-loop hydraulic piston variable pumps, and particularly relates to an integrated replenishing one-way relief valve for closed-loop hydraulic piston variable pumps. Background Technology

[0002] Closed-loop hydraulic variable displacement pumps are widely used in construction machinery such as truck cranes, crawler cranes, road rollers, and aerial work platforms. Compared to open-loop hydraulic systems, closed-loop hydraulic systems, composed of components such as the closed-loop hydraulic variable displacement pump, hydraulic motor, and cylinders, have simpler piping connections. This not only saves installation space but also reduces leakage and vibration issues caused by piping connections, thus improving system reliability. Closed-loop hydraulic systems reduce the chance of air entering the hydraulic fluid, resulting in smoother operation. Furthermore, the closed-loop hydraulic variable displacement pump can directly control the flow direction of the output hydraulic fluid, ensuring a smooth transition and avoiding hydraulic shocks caused by various valves in the hydraulic system. Therefore, closed-loop hydraulic variable displacement pumps are increasingly favored by OEMs.

[0003] Closed-loop hydraulic systems experience continuous oil losses during operation (oil losses due to the volumetric efficiency of the closed-loop hydraulic piston variable pump itself, leakage from the actuator, leakage from pipelines, and leakage from valves within the closed-loop hydraulic system). To compensate for these oil losses and ensure the normal operation of the entire closed-loop hydraulic system, a small-displacement fixed-displacement pump, called a replenishing pump, is typically integrated into the closed-loop hydraulic piston variable pump. The replenishing pump has a smaller displacement and lower pressure, and its outlet pressure is limited by a built-in replenishing relief valve. The closed-loop hydraulic piston variable pump has two independent outlets, A and B, both of which can be used as high-pressure or low-pressure ports. Ports A and B are isolated by two check valves, while simultaneously connected by two high-pressure relief valves. The replenishing pump replenishes the oil lost by the closed-loop hydraulic system to the low-pressure side of port A / B through the check valves, and the replenishing pump is always connected to the low-pressure side of port A / B. The two high-pressure relief valves at ports A and B limit the maximum pressure of their respective ports to prevent overload of the closed hydraulic system. When the pressure of the closed hydraulic system is lower than the opening pressure set by the two high-pressure relief valves, ports A and B are shut off. When the pressure of the closed hydraulic system is higher than the opening pressure set by the two high-pressure relief valves, the high-pressure relief valve on the high-pressure side of ports A and B opens, connecting ports A and B.

[0004] High-pressure relief valves are divided into pilot-operated relief valves and direct-acting relief valves. The basic principle of a high-pressure relief valve is to regulate pressure through negative feedback created by the balance and movement of the valve core.

[0005] The working principle of a pilot-operated relief valve is as follows: When pressurized oil flows in from the inlet, the pressure acts on the lower end face of the main valve core. The valve body is designed with a damping orifice; the pressurized oil passes through this orifice and enters the right chamber of the pilot valve, ultimately acting on the valve core of the pilot-operated relief valve. The valve core of the pilot-operated relief valve is normally closed due to spring force. The spring's pre-adjustment pressure can be adjusted using an external adjustment handle. When the hydraulic pressure is less than the spring pre-adjustment pressure, the pilot valve core remains closed, and the main valve core does not respond. When the system pressure rises, the internal hydraulic pressure of the pilot valve exceeds the spring pre-adjustment pressure, causing the pilot valve to open. Under the pressure reduction effect of the damping orifice, a pressure difference is generated between the upper and lower parts of the main valve core, causing the main valve core to rise. This connects the previously sealed inlet and outlet oil passages, allowing pressurized oil to flow directly from the inlet to the outlet, thus achieving unloading.

[0006] The working principle of a direct-acting relief valve is as follows: When the direct-acting relief valve is connected to the system, hydraulic oil acts on the valve core, generating a force in the opposite direction to the pre-adjusted pressure of the spring. When the inlet pressure is lower than the set pressure of the relief valve, the valve core does not open, and the inlet pressure mainly depends on the external load. When the hydraulic force is greater than the spring pre-adjusted pressure, the valve core opens, and the oil flows back to the tank from the overflow port. The spring force increases with the increase of the relief valve opening until it balances with the hydraulic force. When the relief valve begins to overflow, the pressure at its inlet is basically stable at the set value, thus playing a role in overflow pressure stabilization. The overflow pressure value of the relief valve can be adjusted by adjusting the pre-compression of the spring with the pressure adjusting screw.

[0007] A check valve automatically opens and closes based on the flow of oil, preventing backflow. Typically, check valves are installed with the inlet at the top and the outlet at the bottom. Installing a check valve at the outlet of a closed-loop pump prevents damage to the pump and system due to oil loss, thus protecting the system.

[0008] Based on the working principle of a closed-loop variable displacement pump, it typically lacks a replenishing relief valve function. Therefore, a replenishing check valve and a high-pressure relief valve must be integrated. Since the direct-acting relief valve and the pilot-operated relief valve have different oil inlet methods, different cross-flow circuits must usually be designed on the end cap of the closed-loop variable displacement pump (both ports A and B are on the end cap) to accommodate relief valves with different oil inlet methods. Additionally, an oil inlet circuit needs to be designed on the end cap to cooperate with the replenishing check valve, resulting in numerous end cap configurations and increased manufacturing costs.

[0009] Therefore, there is an urgent need for a new control valve that can simultaneously function as a replenishing check valve and a high-pressure relief valve, and can be used in various oil circuits and different oil inlet methods. This would reduce the number of cross-oil circuits in the rear cover, improve the compatibility of the rear cover, and also reduce the manufacturing cost of the end cover of the closed-type plunger variable pump. Summary of the Invention

[0010] The purpose of this invention is to provide an integrated one-way relief valve for closed-loop hydraulic piston variable pumps. This invention integrates the functions of a one-way relief valve and a high-pressure relief valve, is suitable for both pilot-operated and direct-acting hydraulic circuits, improves end-cap compatibility, and reduces the manufacturing cost of the end-cap for closed-loop hydraulic piston variable pumps.

[0011] The technical solution of the present invention: an integrated oil replenishment one-way relief valve for a closed hydraulic piston variable pump, including a valve sleeve, a large valve core inside the valve sleeve, a small valve core inside the large valve core, a first spring connected to the valve sleeve on the large valve core, and a second spring connected to the large valve core on the small valve core.

[0012] One end of the valve sleeve is provided with a first inlet and outlet, and the side wall of the valve sleeve is provided with a second inlet and outlet; a first open / closed port is formed between the large valve core and the valve sleeve, and the first open / closed port is located between the first inlet and outlet and the second inlet and outlet; a second open / closed port is formed between the large valve core and the small valve core, one side of the second open / closed port is connected to the first inlet and outlet, and the other side of the second open / closed port is connected to the second inlet and outlet.

[0013] It also includes a control oil passage with at least three ports, one end of which is connected to the first inlet and outlet, the other end of which is connected to the inner end face of the large valve core, and the remaining end of which is connected to the outer end face of the small valve core.

[0014] In the aforementioned integrated one-way relief valve for closed-type hydraulic piston variable pump, the inner end of the large valve core is slidably connected to the valve sleeve. The outer circumferential surface of the large valve core is provided with a first step surface and a second step surface. The first step surface is located at the first inlet and outlet, and the second step surface is located at the second inlet and outlet. The second step surface is connected to the first step surface through a first conical surface. The first on / off port is formed between the first conical surface and the valve sleeve.

[0015] In the aforementioned integrated replenishing one-way relief valve for closed-loop hydraulic piston variable pump, a third through hole is provided at the junction of the first conical surface or the first conical surface and the first stepped surface. The third through hole is a component of the control oil passage.

[0016] In the aforementioned integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump, the first spring is located between the valve sleeve and the large valve core. One end of the first spring is connected to the large valve core through a retaining ring, and the other end of the first spring is connected to the first screw plug, which is connected to the end of the valve sleeve.

[0017] In the aforementioned integrated oil replenishment check relief valve for closed-loop hydraulic piston variable pump, the small valve core is provided with a cone, the cone is provided with a second conical surface, and the second through-off port is formed between the second conical surface and the large valve core.

[0018] In the aforementioned integrated oil replenishment check relief valve for a closed-loop hydraulic piston variable pump, the large valve core is provided with a first through hole that communicates with the second inlet and outlet.

[0019] In the aforementioned integrated oil replenishment check relief valve for a closed-loop hydraulic piston variable pump, the inner end of the small valve core is provided with a first spring seat, the small valve core is connected to the conical surface of the first spring seat, the first spring seat is connected to the second spring seat through a second spring, and the second spring seat is connected to the large valve core through a limit pin.

[0020] In the aforementioned integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump, a second screw plug is provided at the end of the large valve core near the first inlet and outlet.

[0021] In the aforementioned integrated one-way relief valve for a closed-loop hydraulic piston variable pump, the small valve core extends radially outward from the end near the second plug to form a piston body. The piston body and the large valve core are in clearance fit, and an oil cavity is formed between the piston body and the second plug. An annular groove is provided on the outer circumferential surface of the small valve core, which is located between the cone and the piston body. A second through hole is provided on the bottom surface of the annular groove, which connects to the end face of the small valve core near the first spring seat. The oil cavity, the clearance between the piston body and the large valve core, the annular groove, and the second through hole are all components of the control oil passage.

[0022] In the aforementioned integrated replenishing one-way relief valve for closed-loop hydraulic piston variable pump, both the first spring seat and the second spring seat are provided with a fourth through hole in the axial direction. The fourth through hole is a component of the control oil passage.

[0023] Compared with the prior art, the present invention has two functions: one-way oil replenishment and high-pressure relief. It is equivalent to integrating the existing oil replenishment check valve and high-pressure relief valve together and connecting them to the A / B port of the closed hydraulic piston variable pump. It is also applicable to both pilot-operated relief valve and direct-acting relief valve circuits. Therefore, there is no need to design complex oil circuits on the end cover of the closed piston variable pump, which can simplify the manufacturing cost of the end cover. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Figure 2 This is a hydraulic schematic diagram of the invention used on a closed-loop hydraulic piston variable pump.

[0026] The markings in the attached diagram are as follows: 1-valve sleeve, 2-large valve core, 3-small valve core, 4-first spring, 5-second spring, 6-first through-hole, 7-second through-hole, 9-first spring seat, 10-second spring seat, 11-limiting pin, 12-oil cavity, 13-fourth through hole;

[0027] 100 - First import / export point; 101 - Second import / export point;

[0028] 200 - First stepped surface, 201 - Second stepped surface, 202 - First conical surface, 203 - Third through hole, 204 - Retaining ring, 205 - First screw plug, 206 - Second screw plug;

[0029] 300 - Cone, 301 - Second conical surface, 303 - First through hole, 304 - Piston body, 305 - Annular groove, 306 - Second through hole; Detailed Implementation

[0030] 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.

[0031] Example. An integrated replenishing check relief valve for a closed-loop hydraulic piston variable pump, such as... Figure 1 As shown, it includes a valve sleeve 1, a large valve core 2 inside the valve sleeve 1, a small valve core 3 inside the large valve core 2, a first spring 4 connected to the valve sleeve 1 on the large valve core 2, and a second spring 5 connected to the large valve core 2 on the small valve core 3.

[0032] One end of the valve sleeve 1 is provided with a first inlet / outlet 100, and the side wall of the valve sleeve 1 is provided with a second inlet / outlet 101; a first open / closed port 6 is formed between the large valve core 2 and the valve sleeve 1, and the first open / closed port 6 is located between the first inlet / outlet 100 and the second inlet / outlet 101; a second open / closed port 7 is formed between the large valve core 2 and the small valve core 3, one side of the second open / closed port 7 is connected to the first inlet / outlet 100, and the other side of the second open / closed port 7 is connected to the second inlet / outlet 101; with the first open / closed port 6 as the boundary, the axial oil pressure area of ​​the side of the large valve core 2 closer to the first inlet / outlet 100 is greater than the oil pressure area of ​​the inner end of the large valve core 2.

[0033] It also includes a control oil passage with three ports. One end of the control oil passage is connected to the first inlet / outlet 100, the other end of the control oil passage is connected to the inner end face of the large valve core 2, and the remaining end of the control oil passage is connected to the outer end face of the small valve core 3.

[0034] The inner end of the large valve core 2 is slidably connected to the valve sleeve 1. The outer circumferential surface of the large valve core 2 is provided with a first step surface 200 and a second step surface 201. The first step surface 200 is located at the first inlet / outlet 100, and the second step surface 201 is located at the second inlet / outlet 101. The second step surface 201 is connected to the first step surface 200 through a first conical surface 202. The first through / break 6 is formed between the first conical surface 202 and the valve sleeve 1.

[0035] A third through hole 203 is provided at the junction of the first conical surface 202 or the first conical surface 202 and the first stepped surface 200. The third through hole 203 is a component of the control oil passage.

[0036] The first spring 4 is located between the valve sleeve 1 and the large valve core 2. One end of the first spring 4 is connected to the large valve core 2 through the retaining ring 204, and the other end of the first spring 4 is connected to the first screw plug 205, which is connected to the end of the valve sleeve 1.

[0037] The small valve core 3 is provided with a cone 300, and a second cone surface 301 is provided on the cone 300. The second through-cut 7 is formed between the second cone surface 301 and the large valve core 2.

[0038] The large valve core 2 is provided with a first through hole 303 that communicates with the second inlet / outlet 101. The first through hole 303 is located on one side of the cone 300.

[0039] The inner end of the small valve core 3 is provided with a first spring seat 9. The small valve core 3 is connected to the conical surface of the first spring seat 9. The first spring seat 9 is connected to the second spring seat 10 through the second spring 5. The second spring seat 10 is connected to the large valve core 2 through the limiting pin 11.

[0040] The large valve core 2 is provided with a second screw plug 206 at the end near the first inlet / outlet 100.

[0041] The small valve core 3 extends radially outward from the end near the second screw plug 206 to form a piston body 304. The piston body 304 is clearance-fitted with the large valve core 2, and an oil cavity 12 is formed between the piston body 304 and the second screw plug 206. An annular groove 305 is provided on the outer circumferential surface of the small valve core 3. The annular groove 305 is located between the cone 300 and the piston body 304 and connects to the third through hole 203. A second through hole 306 is provided on the bottom surface of the annular groove 305. The second through hole 306 connects to the end face of the small valve core 3 near the first spring seat 9. The oil cavity 12, the clearance between the piston body 304 and the large valve core 2, the annular groove 305 and the second through hole 306 are all components of the control oil passage.

[0042] Both the first spring seat 9 and the second spring seat 10 are provided with a fourth through hole 13 in the axial direction. The fourth through hole 13 is a component of the control oil passage.

[0043] Use of this invention: such as Figure 2 As shown, a closed-loop hydraulic piston variable pump uses two replenishing one-way relief valves. One of these valves is designated as valve M, and the other as valve N. Valve M and valve N are connected to ports A and B of the pump, respectively. Port A is connected to the first inlet / outlet 100 of valve N, and port B is connected to the first inlet / outlet 100 of valve M. The second inlet / outlet 101 of valve N is then connected to the second inlet / outlet 101 of valve M. When pressure is high on side A and low on side B, valve M functions as a replenishing one-way valve, and valve N functions as a high-pressure relief valve, with valve N closed. When the pressure on side A reaches the pre-adjusted pressure set by valve N, valve N opens, connecting the oil circuits on sides A and B. The inlet oil flows directly to the outlet, achieving a high-pressure unloading function.

[0044] Specific working principle: When the first inlet and outlet are at 100 high pressure, the high-pressure oil enters the annular groove 305 through the third through hole 203. Part of the high-pressure oil enters the oil chamber 12 through the gap between the piston body 304 and the large valve core 2, connecting the upper end face of the lower valve core. Another part of the high-pressure oil enters the inner cavity of the valve sleeve 1 through the second through hole 306 and the fourth through hole 13, connecting the lower end face of the large valve core 2. Since the oil pressure area at the upper end of the large valve core 2 is smaller than that at the lower end, the large valve core 2 is always in the closed state. The first open / closed port 6 remains open, and the large valve core 2 will not open. When the high-pressure oil pressure continues to rise, because the lower end of the small valve core 3 has a conical surface, the oil pressure area at the upper end of the small valve core 3 is greater than that at the lower end. The small valve core 3 moves downward against the elastic force of the second spring 5, and the second on / off port 7 opens. The high-pressure oil at port A enters port B through the third through hole 203, the annular groove 305, the first through hole 303, and the second inlet / outlet 101. Port A and port B communicate, realizing high-pressure overflow unloading.

[0045] When the first inlet / outlet 100 is under low pressure, the replenishing pressure oil enters the second inlet / outlet 101 from port B. The replenishing pressure oil applies downward pressure to the large valve core 2 through the end face of the second stepped surface 201. When the replenishing pressure reaches the pre-adjusted pressure, the large valve core 2 moves downward against the elastic force of the first spring 4, the first on / off port 6 opens, and the first inlet / outlet 100 and the second inlet / outlet 101 communicate. The replenishing pressure oil from port B enters port A, realizing replenishment. For the small valve core 3, since the oil pressure area on the upper side of the cone 300 is smaller than the oil pressure area on the lower side, the replenishing pressure on the cone 300 is upward, so the second on / off port 7 always remains open, and the small valve core 3 will not open.

Claims

1. An integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump, characterized in that: Includes valve sleeve (1), valve sleeve (1) is provided with a large valve core (2), large valve core (2) is provided with a small valve core (3), large valve core (2) is provided with a first spring (4) connected to valve sleeve (1), and small valve core (3) is provided with a second spring (5) connected to large valve core (2). One end of the valve sleeve (1) is provided with a first inlet and outlet (100), and the side wall of the valve sleeve (1) is provided with a second inlet and outlet (101); a first open / closed port (6) is formed between the large valve core (2) and the valve sleeve (1), and the first open / closed port (6) is located between the first inlet and outlet (100) and the second inlet and outlet (101); a second open / closed port (7) is formed between the large valve core (2) and the small valve core (3), one side of the second open / closed port (7) is connected to the first inlet and outlet (100), and the other side of the second open / closed port (7) is connected to the second inlet and outlet (101); It also includes a control oil passage with at least three ports, one end of which is connected to the first inlet / outlet (100), the other end of which is connected to the inner end face of the large valve core (2), and the remaining end of which is connected to the outer end face of the small valve core (3). The inner end of the small valve core (3) is provided with a first spring seat (9). The small valve core (3) is connected to the conical surface of the first spring seat (9). The first spring seat (9) is connected to the second spring seat (10) through the second spring (5). The second spring seat (10) is connected to the large valve core (2) through the limiting pin (11). The large valve core (2) is provided with a second screw plug (206) at the end near the first inlet / outlet (100). The small valve core (3) extends radially outward from the end near the second screw plug (206) to form a piston body (304). The piston body (304) is in clearance fit with the large valve core (2). An oil cavity (12) is formed between the piston body (304) and the second screw plug (206). An annular groove (305) is provided on the outer circumferential surface of the small valve core (3). The annular groove (305) is located between the cone (300) and the piston body (304). A second through hole (306) is provided on the bottom surface of the annular groove (305). The second through hole (306) connects to the end face of the small valve core (3) near the first spring seat (9). The oil cavity (12), the clearance between the piston body (304) and the large valve core (2), the annular groove (305), and the second through hole (306) are all components of the control oil passage. Both the first spring seat (9) and the second spring seat (10) are provided with a fourth through hole (13) in the axial direction. The fourth through hole (13) is a component of the control oil passage.

2. The integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump according to claim 1, characterized in that: The inner end of the large valve core (2) is slidably connected to the valve sleeve (1). The outer circumferential surface of the large valve core (2) is provided with a first step surface (200) and a second step surface (201). The first step surface (200) is located at the first inlet / outlet (100), and the second step surface (201) is located at the second inlet / outlet (101). The second step surface (201) is connected to the first step surface (200) through the first conical surface (202). The first through / break (6) is formed between the first conical surface (202) and the valve sleeve (1).

3. The integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump according to claim 2, characterized in that: A third through hole (203) is provided at the junction of the first conical surface (202) or the first conical surface (202) and the first stepped surface (200). The third through hole (203) is a component of the control oil passage.

4. The integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump according to claim 2, characterized in that: The first spring (4) is located between the valve sleeve (1) and the large valve core (2). One end of the first spring (4) is connected to the large valve core (2) through the retaining ring (204), and the other end of the first spring (4) is connected to the first screw plug (205). The first screw plug (205) is connected to the end of the valve sleeve (1).

5. The integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump according to claim 1, characterized in that: The small valve core (3) is provided with a cone (300), and the cone (300) is provided with a second cone surface (301). The second through-cut (7) is formed between the second cone surface (301) and the large valve core (2).

6. The integrated replenishing one-way relief valve for a closed-loop hydraulic piston variable pump according to claim 5, characterized in that: The large valve core (2) is provided with a first through hole (303) that communicates with the second inlet and outlet (101).

Images