A load-sensitive variable displacement pump equipped with an electric proportional valve

Abstract

A load-sensitive variable pump provided with an electric proportional valve. The problem that the existing variable pump has a large displacement when starting, resulting in poor stability, high energy consumption, and poor adjustment accuracy during operation is solved. It includes a variable pump, a load-sensitive valve, and an electric proportional valve. The variable pump is provided with a variable pump oil outlet connected to the oil inlet of the main valve. The variable pump includes a rotor assembly for sucking and discharging oil and a limiting mechanism for controlling the displacement of the variable pump. The limiting mechanism includes a rocking member for limiting the rotor assembly and a limiting plunger member for limiting the swing of the rocking member. The variable pump has a first position during installation, a second position during startup, and a third position during operation. The present invention has the advantages of simple structure, convenient assembly, reliable operation, long service life, reliable output, more energy-saving, higher stability, more environmental protection, fast startup response, and high adjustment accuracy.

Description

Technical Field

[0001] The invention relates to a variable displacement pump, in particular to a load-sensitive variable displacement pump provided with an electric proportional valve. Background Art

[0002] A variable displacement pump is a pump with variable displacement. It can be a single-acting vane pump, radial piston pump, or axial piston pump, and is widely used in hydraulic transmission fields such as metallurgy, mining, engineering machinery, ships, and civil aviation ground equipment. In the hydraulic control of large mechanical equipment such as cranes, their movements are usually controlled by a variable displacement pump. Since these mechanical movements are relatively complex, such as boom length adjustment, hoisting, and telescoping, the actual flow rates required for different movements vary. Some hydraulic systems also involve confluence operations, so ordinary simple variable displacement pumps cannot meet these requirements. Currently, a load-sensing valve is installed on the variable displacement pump, which can control the pump's output flow rate according to the size of the load. However, in actual use, when the crane is just started or operating at low speed, the pump output flow rate is very large, and problems such as body shaking, poor stability, and high energy consumption often occur during the crane ignition operation. Summary of the Invention

[0003] In order to solve the problems in the prior art of large displacement of existing variable displacement pumps at startup, resulting in poor stability, high energy consumption, and poor adjustment accuracy during operation, the present invention provides a load-sensitive variable displacement pump equipped with an electric proportional valve.

[0004] The technical solution of the present invention is: a load-sensitive variable pump provided with an electric proportional valve, comprising a variable pump, a load-sensitive valve and an electric proportional valve, the variable pump being provided with a variable pump oil outlet connected to the oil inlet of the main valve, the variable pump comprising a rotor assembly for sucking and discharging oil and a limiting mechanism for controlling the displacement of the variable pump, the limiting mechanism comprising a rocking member for limiting the position of the rotor assembly and a limiting plunger member for limiting the swing position of the rocking member, the variable pump having a first position during installation, a second position during startup and a third position during operation, and when the variable pump is in the second position, the pressure oil at the oil outlet of the variable pump enters the limiting plunger member through the electric proportional valve and is closed by the limiting plunger member The swing angle of the small rocking member causes the variable pump output displacement to gradually decrease in the first state, and the pressure oil at the variable pump outlet passes through the load-sensitive valve and the electric proportional valve into the limit plunger and changes the displacement of the variable pump to zero displacement through the limit plunger. The electric proportional valve is provided with a first valve body, a first valve core and a control unit. When the variable pump is in the third position, the variable pump has a third state in which the output displacement of the variable pump gradually increases when the pressure oil in the limit plunger returns to the oil tank through the electric proportional valve and the load-sensitive valve to release the limit on the rocking member, and a third state in which the control unit controls the first valve core to continue to move so that the output displacement of the variable pump changes to the maximum output displacement.

[0005] As an improvement of the present invention, the electric proportional valve includes a valve sleeve, the first valve core sleeve is arranged in the first valve body, and the first elastic member and the second elastic member are respectively provided at both ends of the first valve core. The first valve core has a first position when installed, a second position in which dynamic balance is achieved through the interaction between the first elastic member and the second elastic member, and a third position controlled by the control unit so that the working flow tends to the maximum output flow.

[0006] As a further improvement of the present invention, the valve sleeve is provided with an adjusting component, which is connected to the first elastic member and adjusts the opening position of the first valve core by adjusting the elastic force of the first elastic member.

[0007] As a further improvement of the present invention, a first connecting sleeve is provided in the valve sleeve, the first elastic member is provided in the first connecting sleeve, one end of the first elastic member is against the first connecting sleeve, and the other first end is against the first valve core, and the adjusting component is against the outer wall of the first connecting sleeve and is used to adjust the elastic force of the first elastic member.

[0008] As a further improvement of the present invention, a second connecting sleeve is provided in the first valve body, the second elastic member is provided in the second connecting sleeve, the first valve body is provided with an installation cavity at one end of the first valve core close to the second connecting sleeve, the rocking member is provided with a feedback rod, the feedback rod is provided with a pushing member, the pushing member is inserted into the installation cavity and is used to push the second connecting sleeve.

[0009] As a further improvement of the present invention, the first valve body is provided with a first oil hole, a second oil hole and a third oil hole, and the first valve core moves axially so that the second oil hole is connected to the first oil hole and the third oil hole respectively.

[0010] As a further improvement of the present invention, the load-sensitive valve includes a second valve body and a second valve core. The second valve core is arranged in the second valve body and slides relative to the second valve body. One end of the second valve core is provided with a pressure regulating component for adjusting the opening pressure of the second valve core.

[0011] As a further improvement of the present invention, the pressure regulating assembly includes a pressure regulating part and a pressing part, the pressing part and the second valve core are offset against each other, and a pressure regulating spring is provided between the pressure regulating part and the pressing part.

[0012] As a further improvement of the present invention, the second valve body is provided with a fourth oil hole, a fifth oil hole and a sixth oil hole, the fourth oil hole is connected to the oil outlet of the variable pump, the fifth oil hole is connected to the third oil hole on the first valve body, and the sixth oil hole is connected to the main valve.

[0013] As a further improvement of the present invention, a seventh oil hole is provided on the second valve body, and the fourth oil hole is connected to the third oil hole on the first valve body through the fifth oil hole when the variable pump is in the second state, and the sixth oil hole is connected to the oil return port of the main valve when the variable pump is in the first state, and when the variable pump is in the third state, the sixth oil hole is connected to the oil inlet of the main valve, and the third oil hole is connected to the oil tank through the fifth oil hole and the seventh oil hole.

[0014] The present invention has the beneficial effects of providing a load-sensing valve and an electric proportional valve, enabling the variable displacement pump to output at low or even zero displacement during startup or at low speeds, thereby saving energy and protecting the environment, preventing vehicle vibration, providing excellent stability, and providing a fast response speed during operation. Furthermore, the electric proportional control enables precise control within a certain flow range, resulting in high control accuracy and greater energy conservation and environmental protection. The present invention also has the advantages of a simple structure, easy assembly, reliable operation, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attachment Figure 1 Schematic diagram of the structure of an embodiment of the present invention.

[0016] Attachment Figure 2 For attachment Figure 1 Schematic diagram of the structure after removing the electric proportional valve 3.

[0017] Attachment Figure 3 For attachment Figure 1 Schematic diagram of the structure of the load sensing valve 2.

[0018] Attachment Figure 4 For attachment Figure 3 Schematic diagram of the cross-sectional structure.

[0019] Attachment Figure 5 For attachment Figure 1 Schematic diagram of the structure of the CEC proportional valve 3.

[0020] Attachment Figure 6 For attachment Figure 5 Schematic diagram of the structure in another direction.

[0021] Attachment Figure 7 For attachment Figure 5 Schematic diagram of the half-section structure.

[0022] Attachment Figure 8 For attachment Figure 5 Schematic diagram of the half-section structure in another direction.

[0023] Attachment Figure 9 For attachment Figure 5 Schematic diagram of the explosion structure.

[0024] In the figure, 1, variable pump; 11, variable pump oil outlet; 12, rotor assembly; 13, limit mechanism; 131, rocking member; 1311, feedback lever; 1312, push member; 132, limit plunger member; 14, reset mechanism; 2, load-sensing valve; 21, second valve body; 23, second valve core; 24, pressure-regulating assembly; 241, pressure-regulating member; 242, top pressure member; 243, pressure-regulating spring; 25, fourth oil hole; 26, fifth oil hole; 27, sixth oil hole; 28, Seventh oil hole; 3. Electric proportional valve; 31. First valve body; 311. First elastic member; 312. Second elastic member; 313. Mounting cavity; 314. First oil hole; 315. Second oil hole; 316. Third oil hole; 32. Valve sleeve; 33. Control unit; 331. Push rod; 34. First valve core; 35. Adjustment assembly; 351. Adjustment screw; 3511. Inclined surface; 36. First connecting sleeve; 361. Conical surface portion; 37. Second connecting sleeve; 38. Connecting piece. DETAILED DESCRIPTION

[0025] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0026] Depend on Figure 1 Combine Figure 2-9As shown, a load-sensitive variable pump provided with an electric proportional valve includes a variable pump 1, a load-sensitive valve 2 and an electric proportional valve 3. The variable pump 1 is provided with a variable pump oil outlet 11 connected to the oil inlet of the main valve. The variable pump 1 includes a rotor assembly 12 for sucking and discharging oil and a limiting mechanism 13 for controlling the displacement of the variable pump 1. The limiting mechanism 13 includes a rocking member 131 for limiting the rotor assembly 12 and a limiting plunger 132 for swinging and limiting the rocking member 131. Specifically, the rotation of the rotor assembly in the variable pump drives the suction and discharge of oil, and the limiting plunger introduces pressurized oil to limit the rocking member to adjust and control the pump displacement, and the rocking member is reset by the reset mechanism 14, etc., which are existing technologies and will not be described again. The variable pump 1 has a first position when installed, a second position when started and a third position when working. When the variable pump 1 is in the second position, the pressure oil at the variable pump outlet 11 enters the limit plunger 132 through the electric proportional valve 3 and closes the swing angle of the rocking member 131 through the limit plunger 132, so that the output displacement of the variable pump 1 gradually decreases. The pressure oil at the variable pump outlet 11 passes through the load sensing valve 2 and the electric proportional valve 3 and enters the limit plunger 132 and closes the swing angle of the rocking member 131 through the limit plunger 132. The electric proportional valve 3 is provided with a first valve body 31, a first valve core 34, and a control unit 33. When the variable pump 1 is in the third position, the variable pump 1 has a third state in which the output displacement of the variable pump 1 gradually increases when the pressure oil in the limit plunger 132 returns to the oil tank through the electric proportional valve 3 and the load-sensing valve 2 to release the limit on the rocking member 131, and a third state in which the control unit 33 controls the first valve core 34 to continue to move, causing the output displacement of the variable pump 1 to move toward the maximum output displacement. The beneficial effects of the present invention are that the provision of the load-sensing valve and the electric proportional valve enables the variable pump to output at low or even zero displacement during startup or at low speed, which is energy-saving and environmentally friendly, avoids vehicle body vibration, has good stability, and has a fast response speed during operation. Moreover, through electric proportional control, it can accurately control within a certain flow range, has high control accuracy, and is more energy-saving and environmentally friendly. The present invention also has the advantages of simple structure, easy assembly, reliable operation, and long service life.Take a crane as an example for further explanation: when the present invention is used in conjunction with the main valve of the crane, after the crane is ignited, since the LS port (i.e., the sixth oil hole 27) of the load-sensing valve is connected to the main valve oil return port T, the variable pump oil outlet 11 is connected to the oil inlet P of the crane main valve, and since the main valve stem of the main valve is in the middle position at this time, the oil at the variable pump outlet cannot flow out and is blocked. The pressure at the variable pump oil outlet rises instantaneously. As the pressure at the variable pump oil outlet rises, the variable pump oil outlet is connected to the first oil hole of the electric proportional valve through the internal oil channel and the external oil channel. The pressure oil in the first oil hole enters the second oil hole through the movement of the first valve core of the electric proportional valve. The pressure oil in the second oil hole enters the limit plunger, causing the variable pump to move in the direction of small displacement, that is, the variable pump is in the first state; when the variable reaches the set displacement value Q (at this time, the control unit of the electric proportional valve is not energized, and it adjusts its Q value through the adjustment component, that is, the dynamic balance of the first valve core is achieved through the cooperation of the first elastic member, the second elastic member and the pressure at the feedback rod push member and the adjustment component), the pressure at the oil outlet 11 of the variable pump continues to rise. When the pressure rises to the load sensitive set pressure value △P (that is, when the set pressure of the pressure regulating component is overcome), the second valve core moves to the right under the push of the pressure at the fourth oil hole (see. Figure 4), so that the pressure oil in the fourth oil hole enters the limit plunger through the fifth oil hole, the third oil hole, and the second oil hole, and continues to push the rocking member to swing (the swing angle becomes smaller), so that the variable pump changes to zero displacement, that is, the variable pump is in the second state; the above process is an instantaneous process. Under actual working conditions, after the crane is ignited, the variable pump instantly becomes zero displacement under the action of the electric proportional and load-sensitive valve, so that the variable pump is at zero displacement when the crane is idling, which is energy-saving and environmentally friendly, reduces vehicle body vibration, has good product stability, and low energy consumption. When the crane needs to work, when the crane main valve needs to work, the LS port of the load-sensing valve is connected to the P port of the main valve, and the main valve stem is moved. At this time, oil flows out of the variable pump oil outlet, and the second valve core moves to the left under the action of the pressure regulating spring of the pressure regulating assembly. At this time, the oil in the limit plunger returns to the oil tank through the second oil hole, the third oil hole, the fifth oil hole, and the seventh oil hole. At this time, the variable pump rocking member moves to the maximum displacement under the action of the reset mechanism 14 (the reset mechanism usually includes a reset spring and a reset piston), that is, the first oil port selects the high-pressure oil at the variable pump oil outlet to enter the limit plunger through the second oil hole, and the high-pressure oil in the limit plunger passes through the second oil hole. The oil through hole and the third oil through hole return to the oil tank, the first valve core is in a dynamic balance state, and the variable pump reaches the set displacement value Q, that is, the variable pump is in the third state; at this time, the control force of the control unit is increased (usually precise control is provided by the current of the solenoid valve). At this time, the push rod of the control unit pushes the first valve core to overcome the thrust of the feedback rod pushing piece, and the displacement of the variable pump will change from the set displacement value Q to the maximum displacement, that is, the variable pump is in the fourth state; the increase in current is related to the car throttle, and the current increases accordingly when the car throttle is increased. The present invention performs adjustment control after the pump displacement reaches the Q value, and its control accuracy is higher, which is more in line with the actual working conditions of the crane.

[0027] The electric proportional valve 3 includes a valve sleeve 32, a first valve core 34 sleeved within a first valve body 31, and first and second elastic members 311 and 312, respectively, at either end of the first valve core 34. The first valve core 34 has a first position when installed, a second position in which dynamic balance is achieved through the interaction of the first and second elastic members 311 and 312, and a third position controlled by a control unit 33, in which the operating flow rate approaches the maximum output flow rate. Specifically, an adjustment assembly 35 is provided on the valve sleeve 32. The adjustment assembly 35 is connected to the first elastic member 311 and adjusts the opening position of the first valve core 34 by adjusting the elastic force of the first elastic member 311. The present invention advantageously provides an adjustment assembly that adjusts the force applied to the first valve core, thereby adjusting the flow rate output of the electric proportional valve. When energized, the electromagnetically controlled flow rate is electrically proportionally controlled from the set value, resulting in high adjustment accuracy. The present invention also has the advantages of simple structure, easy assembly, reliable operation, and long service life. The present invention utilizes a first elastic member and a second elastic member to force the valve core to open to a certain position during operation, achieving dynamic balance and thereby allowing the output flow rate to reach a set value (Q). When the control unit is activated, it can continue to control the movement of the first valve core, thereby causing the flow rate on the valve body to change toward the maximum output flow rate. Of course, in actual production, it can also be controlled toward the minimum flow rate. This allows the proportional valve to be controlled from the original zero to maximum flow rate to a variable control from the Q value to the maximum flow rate, making the control of the valve core and flow rate more sensitive to the unit current and more precise.

[0028] The valve sleeve 32 is provided with a first connecting sleeve 36. The first elastic member 311 is sleeved within the first connecting sleeve 36. One end of the first elastic member 311 abuts against the first connecting sleeve 36, while the other first end abuts against the first valve core 34. The adjustment assembly 35 abuts against the outer wall of the first connecting sleeve 36 and is used to adjust the elastic force of the first elastic member 311. Specifically, the outer wall of the first connecting sleeve 36 is provided with a tapered portion 361 to facilitate the pushing of the adjustment assembly 35. More specifically, the adjustment assembly 35 includes an adjusting screw 351, which abuts against the tapered portion 361 of the first connecting sleeve 36. The extended line of the adjusting screw 351's center falls on the tapered portion 361 of the first connecting sleeve 36. More specifically, the adjusting screw 351 passes through the valve sleeve 32 and abuts against the outer wall of the first connecting sleeve 36. The adjusting screw 351 is provided with an inclined surface 3511 that mates with the tapered portion 361. This structure allows the set value Q to be adjusted by the adjusting screw, and the cooperation between the inclined surface and the conical surface makes the adjusting screw reliable and convenient to adjust. The provision of the first connecting sleeve facilitates pressing the first valve core, driving the first valve core to move, and adjusting the elastic force of the first elastic member.

[0029] The control unit 33 is located at one end of the first valve core 34 near the first connecting sleeve 36. The control unit 33 is provided with a push rod 331 for pushing the first valve core 34. This structure facilitates the control unit to drive the first valve core to move. Specifically, the control unit can use electromagnetic force to drive the push rod to move.

[0030] The first valve body 31 is provided with a second connecting sleeve 37, and the second elastic member 312 is sleeved within the second connecting sleeve 37. The first valve body 31 is provided with a mounting cavity 313 at one end of the first valve core 34 near the second connecting sleeve 37. The rocking member 131 is provided with a feedback rod 1311, and the feedback rod 1311 is provided with a pushing member 1312. The pushing member 1312 is inserted into the mounting cavity 313 and is used to push the second connecting sleeve 37. This enables feedback control of the output of the electric proportional valve.

[0031] The first valve core 34 is provided with a connecting piece 38. One end of the second elastic member 312 abuts against the second connecting sleeve 37, while the other end abuts against the connecting piece 38. The connecting piece 38 is inserted into the second connecting sleeve 37. This structure makes it convenient and reliable for the second elastic member to press against the first valve core, facilitating reliable operation of the first valve core.

[0032] The first valve body 31 is provided with a first oil hole 314, a second oil hole 315, and a third oil hole 316. The first valve core 34 axially moves, causing the second oil hole 315 to communicate with the first and third oil holes 314, 316, respectively. The second oil hole is connected to a stopper. When the variable pump is in the first state, the first and second oil holes 314, 315 communicate, causing the first valve core to move toward the second position. When the variable pump is in the second state, the third oil hole 316 communicates with the second oil hole and contains high-pressure oil, meaning that the third oil hole supplies oil to the second oil hole. When the variable pump is in the third state, the second oil hole communicates with the third oil hole and contains high-pressure oil, meaning that the second oil hole supplies oil to the third oil hole. This structure allows the connection between the second oil hole and the stopper to be switched by the different positions of the first valve core, making the present invention convenient and reliable to control.

[0033] The load-sensing valve 2 comprises a second valve body 21 and a second valve core 23. The second valve core 23 is disposed within the second valve body 21 and slidably engages with the second valve body 21. A pressure-regulating assembly 24 is provided at one end of the second valve core 23 for adjusting the opening pressure of the second valve core 23. Specifically, the pressure-regulating assembly 24 comprises a pressure-regulating member 241 and a pressure member 242. The pressure member 242 abuts against the second valve core 23, with a pressure-regulating spring 243 interposed between the pressure-regulating member 241 and the pressure member 242. The pressure-regulating assembly can adjust and balance the load-sensing opening value. More specifically, the presence of two pressure-regulating springs enhances product stability.

[0034] The second valve body 21 is provided with a fourth oil hole 25, a fifth oil hole 26, and a sixth oil hole 27. The fourth oil hole 25 is connected to the variable pump oil outlet 11, the fifth oil hole 26 is connected to the third oil hole 316 on the first valve body 31, and the sixth oil hole 27 is connected to the main valve. Specifically, the second valve body 21 is provided with a seventh oil hole 28. The fourth oil hole 25 is connected to the third oil hole 316 on the first valve body 31 via the fifth oil hole 26 when the variable pump 1 is in the second state. The sixth oil hole 27 is connected to the oil return port of the main valve when the variable pump 1 is in the first state. When the variable pump 1 is in the third state, the sixth oil hole 27 is connected to the oil inlet of the main valve. The third oil hole 316 is connected to the oil tank via the fifth oil hole 26 and the seventh oil hole 28. Such a structure makes the product operate reliably, and through the coordinated control of the load-sensing valve and the electric proportional valve, the variable pump has the advantages of reliable output, more energy-saving, higher stability, more environmental protection, fast start-up response, and high adjustment accuracy.

[0035] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or they can refer to internal connections between two components. A person of ordinary skill in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0037] Technical personnel should note: Although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention. Any modification using the inventive concept will be included in the scope of protection of this patent.

Claims

1. A load-sensitive variable displacement pump equipped with an electric proportional valve, characterized in that The invention comprises a variable pump (1), a load-sensitive valve (2) and an electric proportional valve (3); the variable pump (1) is provided with a variable pump oil outlet (11) connected to the oil inlet of the main valve; the variable pump (1) comprises a rotor assembly (12) for sucking and discharging oil and a limit mechanism (13) for controlling the displacement of the variable pump (1); the limit mechanism (13) comprises a swing member (131) for limiting the position of the rotor assembly (12) and a limit plunger member (132) for limiting the swing position of the swing member (131); the variable pump (1) has a first position when installed, a second position when started and a third position when working; when the variable pump (1) is in the second position, the pressure oil at the variable pump oil outlet (11) enters the electric proportional valve (3) through the pressure oil at the variable pump oil outlet (11). The first state in which the displacement of the variable pump (1) is gradually reduced by the limit plunger (132) and the swing angle of the swing member (131) is reduced by the limit plunger (132), and the pressure oil at the oil outlet (11) of the variable pump enters the limit plunger (132) through the load sensing valve (2) and the electric proportional valve (3) and the displacement of the variable pump (1) is changed to zero displacement by the limit plunger (132). The electric proportional valve (3) is provided with a first valve body (31), a first valve core (34) and a control unit (33). When the variable pump (1) is in the third position, the pressure oil in the limit plunger (132) of the variable pump (1) is returned to the oil tank through the electric proportional valve (3) and the load sensing valve (2) to release the swing angle of the swing member. The electric proportional valve (3) comprises a valve sleeve (32), the first valve core (34) is sleeved in the first valve body (31), the two ends of the first valve core (34) are respectively provided with a first elastic member (311) and a second elastic member (312), the first valve core (34) has a first position when installed, a second position in which dynamic balance is achieved through the interaction of the first elastic member (311) and the second elastic member (312), and a third position in which the working flow rate tends to the maximum output flow rate under the control of the control unit (33). The valve sleeve (32) is provided with an adjusting component (35), the adjusting component (35) is connected to the first elastic member (311) and adjusts the opening position of the first valve core (34) by adjusting the elastic force of the first elastic member (311), the valve sleeve (32) is provided with a first connecting sleeve (36), the first elastic member (311) is sleeved in the first connecting sleeve (36), one end of the first elastic member (311) is against the first connecting sleeve (36), and the other first end is against the first valve core (34), the adjusting component (35) is against the outer wall of the first connecting sleeve (36) and is used to adjust the elastic force of the first elastic member (311), and the first valve body (31) is provided with a second connecting sleeve (37),The second elastic member (312) is sleeved in the second connecting sleeve (37); the first valve body (31) is provided with a mounting cavity (313) at one end of the first valve core (34) close to the second connecting sleeve (37); the rocking member (131) is provided with a feedback rod (1311); the feedback rod (1311) is provided with a pushing member (1312); the pushing member (1312) is inserted into the mounting cavity (313) and is used to push the second connecting sleeve (37).

2. A load-sensing variable displacement pump with an electric proportional valve according to claim 1, characterized in that The first valve body (31) is provided with a first oil hole (314), a second oil hole (315) and a third oil hole (316); the first valve core (34) is axially moved so that the second oil hole (315) is connected to the first oil hole (314) and the third oil hole (316) respectively; the second oil hole is connected to the limit plunger; when the variable pump is in the first state, the first oil hole (314) is connected to the second oil hole (315) and the first valve core is moved to the second position; when the variable pump is in the second state, the third oil hole (316) is connected to the second oil hole and high-pressure oil is provided in the third oil hole; when the variable pump is in the third state, the second oil hole is connected to the third oil hole and high-pressure oil is provided in the second oil hole.

3. A load-sensing variable displacement pump with an electric proportional valve according to claim 2, characterized in that The load-sensitive valve (2) comprises a second valve body (21) and a second valve core (23); the second valve core (23) is arranged in the second valve body (21) and is slidably engaged with the second valve body (21); and a pressure regulating component (24) for regulating the opening pressure of the second valve core (23) is provided at one end of the second valve core (23).

4. A load-sensing variable displacement pump with an electric proportional valve according to claim 3, characterized in that The pressure regulating assembly (24) comprises a pressure regulating member (241) and a pressing member (242), the pressing member (242) and the second valve core (23) being in contact with each other, and a pressure regulating spring (243) is provided between the pressure regulating member (241) and the pressing member (242).

5. A load-sensing variable displacement pump with an electric proportional valve according to claim 3, characterized in that The second valve body (21) is provided with a fourth oil hole (25), a fifth oil hole (26) and a sixth oil hole (27); the fourth oil hole (25) is connected to the oil outlet (11) of the variable pump, the fifth oil hole (26) is connected to the third oil hole (316) on the first valve body (31), and the sixth oil hole (27) is connected to the main valve.

6. A load-sensing variable displacement pump with an electric proportional valve according to claim 5, characterized in that The second valve body (21) is provided with a seventh oil hole (28); the fourth oil hole (25) is connected to the third oil hole (316) on the first valve body (31) through the fifth oil hole (26) when the variable pump (1) is in the second state; the sixth oil hole (27) is connected to the oil return port of the main valve when the variable pump (1) is in the first state; when the variable pump (1) is in the third state, the sixth oil hole (27) is connected to the oil inlet of the main valve; and the third oil hole (316) is connected to the oil tank through the fifth oil hole (26) and the seventh oil hole (28).

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