An adjustable power valve device, system and method of controlling the same

Abstract

The application provides a power-adjustable valve device, system and control method thereof, which comprises an electric proportional valve, a valve core, a spring, an eccentric latch, a flow distribution disc, a swash plate, a variable piston, a plunger slipper assembly, a solenoid valve block, a shell, a pump shell, a sliding block, a pump cylinder body and a throttle valve. The electric proportional valve is installed on the solenoid valve block, the solenoid valve block is connected with the shell through an oil passage Pf, the valve core, the spring and the eccentric latch are all installed in the shell, the pressure output by the solenoid valve acts on the valve core through the oil passage Pf, the flow distribution disc is installed on the shell, the positioning pin hole of the flow distribution disc adopts a U-shaped structure, and the eccentric latch ball head is connected with the U-shaped groove of the flow distribution disc through one end. The flow distribution disc is controlled by the electric proportional valve, the valve core, the spring and the eccentric latch to distribute flow, so that the problem that the engine power cannot be fully utilized is effectively avoided, the energy-saving effect is achieved, the number of parts is reduced, and the product cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of hydraulic pumps, and more particularly to an adjustable power valve device, system, and control method thereof. Background Technology

[0002] Currently, the hydraulic power source of engineering machinery at home and abroad generally adopts constant power control piston pump. The purpose is to adjust the pump's flow output according to the outlet pressure, so that the pump's output flow and outlet pressure satisfy a hyperbolic function relationship, making full use of the engine power to achieve energy saving.

[0003] Analyzing existing hydraulic direct-control variable displacement piston pumps used in skid steer loaders, the power value at a specific speed (i.e., the constant power pressure inflection point) is set by adjusting the position of the eccentric bolt on the distributor plate according to the engine characteristic curve. After the power value is adjusted, the eccentric bolt is tightened. If the eccentric bolt position is not adjusted properly, the following situations may occur: the power value is set too high, causing engine stalling; the power value is set too low, failing to fully utilize engine power, resulting in power loss. Therefore, adjusting the eccentric bolt position is crucial, and because the adjustment method is mechanical and manual, the adjustment precision is low, leading to a certain deviation in the power setting.

[0004] When the engine speed changes, the engine power changes accordingly. Since the position of the eccentric bolt on the distributor plate does not change, the pump power value does not change. Therefore, the pump power and the engine power cannot be well matched. This structure does not have a real-time power adjustment function, which will cause the engine power to be wasted at other speeds.

[0005] Existing technical solutions all use constant power control valves to control the pump at constant power. These control valves have many parts and require high machining precision. Existing technical solutions use rotating distribution plates to achieve vibration and noise reduction, but they cannot achieve constant power control. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adjustable power valve device, system and control method thereof.

[0007] To address the problems of existing technologies, this invention discloses an adjustable power valve device, comprising an electro-proportional valve, a valve core, a spring, and a distribution plate; one end of the valve core is connected to the electro-proportional valve via an oil circuit, and the other end is connected to the spring; the valve core is connected to the distribution plate via a transmission structure, and the distribution plate is provided with an oil suction groove, an oil discharge groove, and a vibration damping groove surrounding its center; the pressure oil output by the electro-proportional valve acts on the valve core through the oil circuit, and when the force on the valve core is greater than the spring force, the valve core, driven by the pressure oil, drives the distribution plate to rotate through the transmission structure.

[0008] Furthermore, the transmission structure includes an eccentric pin disposed on the valve core and a U-shaped groove disposed on the distribution plate; the eccentric pin includes a ball head and a connecting post, the ball head being located in the U-shaped groove, and the connecting post being connected to the valve core.

[0009] Furthermore, the transmission structure includes a U-shaped groove in the valve core and an eccentric pin in the distribution plate; the eccentric pin includes a ball head and a connecting post, the ball head is connected to the distribution plate through the connecting post, and the ball head is located in the U-shaped groove.

[0010] Accordingly, an adjustable power valve system includes: a swashplate, a variable piston, a plunger slipper assembly, a solenoid valve block, a housing, a pump housing, a slider, and a pump cylinder; it also includes the aforementioned adjustable power valve device; the solenoid valve block and the pump housing are respectively connected to the housing; an electro-proportional valve is installed on the solenoid valve block, and the valve core, spring, and distributor plate are all installed inside the housing; the swashplate, variable piston, slider, and pump cylinder are all located inside the pump housing; the swashplate is connected to the variable piston via the slider, the plunger slipper assembly is located inside the pump cylinder, and the end face of the plunger slipper assembly presses against the swashplate; the distributor plate communicates with the pump cylinder, and the pump's output shaft passes through the swashplate.

[0011] Furthermore, it also includes a throttle valve for connecting the variable piston and the oil tank.

[0012] Accordingly, the control method for the aforementioned adjustable power valve system:

[0013] When the control pressure acting on the variable piston stabilizes at a certain value, the swashplate is in a state of force equilibrium. When the outlet pressure increases, the force equilibrium of the swashplate will be broken, and the swashplate will tend to swing. The product of the pressure value that breaks the equilibrium and the flow rate is the constant power value of the pump. This point is the constant power inflection point.

[0014] If it is necessary to reduce the pressure value corresponding to breaking the force balance of the swashplate, the input current of the electro-proportional valve is reduced, and its output pressure oil also decreases accordingly. The output pressure oil of the electro-proportional valve acts on the valve core. When the force on the valve core is less than the spring force, the force balance of the valve core is broken. Driven by the spring force, the valve core drives the distribution plate to rotate through the transmission structure, thereby reducing the mismatch angle of the distribution plate. When the force on the valve core reaches equilibrium again, the valve core stops moving, the distribution plate stops rotating, and the mismatch angle of the distribution plate is fixed at a certain angle. When the torque of the variable piston acting on the swashplate remains unchanged, in order to maintain the balance of the swashplate, the torque of the plunger slipper assembly acting on the swashplate cannot be changed either. When the mismatch angle decreases, the torque of the plunger slipper assembly acting on the swashplate will increase. The pressure value is reduced to keep the torque of the plunger slipper assembly on the swashplate constant, the pressure value corresponding to breaking the force balance of the swashplate decreases, and the constant power pressure inflection point is reduced.

[0015] Furthermore, when it is necessary to increase the pressure value corresponding to breaking the force balance of the swashplate, the input current of the electro-proportional valve is increased, and its output pressure oil also increases accordingly. The pressure oil output by the electro-proportional valve acts on the valve core. When the force on the valve core is greater than the spring force, the force balance of the valve core is broken. Under the push of the pressure oil, the valve core drives the distribution plate to rotate through the transmission structure, thereby increasing the mismatch angle of the distribution plate. When the force on the valve core reaches equilibrium again, the valve core stops moving, the distribution plate stops rotating, and the mismatch angle of the distribution plate is fixed at a certain angle. As the mismatch angle increases, the torque of the plunger slipper assembly acting on the swashplate decreases. The pressure value is increased to keep the torque of the plunger slipper assembly on the swashplate constant, thus increasing the pressure value corresponding to breaking the force balance of the swashplate and increasing the constant power pressure inflection point.

[0016] Furthermore, after entering the constant power stage, as the pump outlet pressure increases, the swashplate swings back to a smaller angle. During the swing of the swashplate, it drives the variable piston to move. At this time, the pressure oil in the variable piston chamber flows back to the oil tank through the throttle valve. When the pump outlet pressure decreases, the variable piston drives the swashplate to swing to a larger angle. At this time, the variable piston controls the pressure oil to flow into the variable piston chamber in part and flow back to the oil tank through the throttle valve in part.

[0017] Furthermore,

[0018] The torque balance equation for the swashplate of the plunger slipper assembly is:

[0019]

[0020] F a The force on the variable piston is L; L is the lever arm of the variable piston. The torque exerted on the swashplate by the plunger slipper assembly;

[0021] When the torque of the variable piston on the swashplate is greater than the torque of the piston slipper assembly on the swashplate, the swashplate tilt angle tends to increase; when the torque of the variable piston on the swashplate is less than the torque of the piston slipper assembly on the swashplate, the swashplate tilt angle tends to decrease.

[0022] The force equation for the variable piston is:

[0023] F a =PA (2)

[0024] P is the pilot hydraulic pressure; A is the variable piston area.

[0025] Furthermore,

[0026] The equation for the torque of the plunger slipper assembly acting on the swashplate is as follows:

[0027]

[0028] N is the number of plungers; AP P is the area of ​​the plunger; d P is the pump outlet pressure. i The inlet pressure of the pump is r; the radius of the distribution circle is r; M is M. P For the plunger mass; M s Let α be the mass of the shoe; α be the inclination angle of the swashplate. This represents the closed dead angle; φ represents the high-low pressure cross angle. It's a mismatched role.

[0029] The beneficial effects of this invention are as follows:

[0030] This invention provides a valve device with variable constant power and pressure cut-off value. It controls the flow distribution plate through an electro-proportional valve, valve core, spring, and eccentric pin, which effectively avoids the problem of insufficient engine power and achieves energy saving effect. At the same time, it reduces the number of parts and lowers product cost. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an adjustable power valve device according to the present invention;

[0032] Figure 2 This is a schematic diagram of the valve core, eccentric pin, and distribution plate in an adjustable power valve device of the present invention.

[0033] Figure 3 This is a schematic diagram of another connection form between the eccentric pin and the distribution plate in an adjustable power valve device of the present invention.

[0034] Figure 4 This is a schematic diagram of an adjustable power valve system according to the present invention;

[0035] Figure 5 This is a schematic diagram of the variable piston position in an adjustable power valve system according to the present invention.

[0036] Figure 6 This is a diagram of a swashplate-variable piston structure in an adjustable power valve system according to the present invention.

[0037] Figure 7 This is a flow path diagram of the throttle valve housing of an adjustable power valve system according to the present invention;

[0038] Figure 8 This is a schematic diagram illustrating the working principle of an adjustable power valve system according to the present invention.

[0039] Figure 9 This is a power curve diagram of an adjustable power valve system according to the present invention.

[0040] Figure 10 This is a schematic diagram of the distribution plate structure of an adjustable power valve system according to the present invention.

[0041] Figure label:

[0042] 1. Electro-proportional valve; 2. Valve core; 3. Spring; 4. Eccentric pin; 5. Distribution plate; 6. Swashplate; 7. Variable piston; 8. Piston slipper assembly; 9. Solenoid valve block; 10. Housing; 11. Pump housing; 12. Slider; 13. Pump cylinder; 14. Throttle valve. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] like Figure 1-2 As shown, an adjustable power valve device of the present invention includes an electro-proportional valve 1, a valve core 2, a spring 3, and a distribution plate 5. One end of the valve core 2 is connected to the electro-proportional valve 1 via an oil circuit, and the other end is connected to the spring 3. The valve core 2 is connected to the distribution plate 5 via a transmission structure. The distribution plate 5 is provided with an oil suction groove, an oil discharge groove, and a vibration damping groove surrounding its center. The pressure oil output by the electro-proportional valve 1 acts on the valve core 2 through the oil circuit. When the force on the valve core 2 is greater than the spring force of the spring 3, the valve core 2 is driven by the pressure oil to rotate the distribution plate 5 through the transmission structure. The transmission structure includes an eccentric pin 4 provided on the valve core 2 and a U-shaped groove provided on the distribution plate 5. The eccentric pin 4 includes a ball head and a connecting post. The ball head is located in the U-shaped groove, and the connecting post is connected to the valve core 2. The valve core 2 shown has a boss at its end for connecting the spring 3, and a slot on its side for the eccentric pin 4 and connecting post to be inserted.

[0045] like Figure 3 As shown, the present invention also provides another form of transmission structure including a U-shaped groove provided in the valve core 2 and an eccentric pin 4 provided in the distribution plate 5; the eccentric pin 4 includes a ball head and a connecting post, the ball head is connected to the distribution plate 5 through the connecting post, and the ball head is located in the U-shaped groove.

[0046] like Figure 4 As shown, the adjustable power valve system provided by the present invention includes, in addition to the valve device described above, a swashplate 6, a variable piston 7, a plunger slipper assembly 8, a solenoid valve block 9, a housing 10, a pump housing 11, a slider 12, a pump cylinder 13, and a throttle valve 14.

[0047] The electro-proportional valve 1 is mounted on the solenoid valve block 9. The solenoid valve block 9 is connected to the housing 10 via the flow channel Pf oil passage. The valve core 2, spring 3, and eccentric pin 4 are all installed inside the housing 10. The pressure output by the solenoid valve 1 acts on the valve core 2 through the oil passage Pf. One end of the valve core 2 has a boss for mounting the spring 3. One end of the spring 3 rests against the housing. The distribution plate 5 is mounted on the housing 10. The positioning pin hole of the distribution plate 5 adopts a U-shaped structure. One end of the eccentric pin 4 is a ball head, and the other end is cylindrical. The cylindrical end of the eccentric pin 4 is vertically inserted into the cylindrical cavity of the valve core 2. The ball head end of the eccentric pin 4 is connected to the U-shaped groove of the distribution plate 5. The pump output shaft passes through the swashplate 6.

[0048] like Figure 5 , 6 As shown, the variable piston 7 is installed inside the pump housing 11, and the swashplate 6 is connected to the variable piston 7 via the slider 12, as shown. Figure 5 As shown, the pump cylinder body 13 is located inside the pump housing 11, the plunger slipper assembly 8 is installed inside the pump cylinder body 13, and the slipper end face presses against the swashplate 6.

[0049] like Figure 8 , 9 As shown, the working principle of the adjustable power valve system provided by the present invention is as follows:

[0050] The torque balance equation for the plunger slipper assembly 8 and swashplate 6 is:

[0051]

[0052] F a The force on variable piston 7; L is the lever arm of variable piston 7; The torque exerted by the plunger slipper assembly 8 on the swashplate 6;

[0053] When the torque of the variable piston 7 acting on the swashplate 6 is greater than the torque of the piston slipper assembly 8 acting on the swashplate 6, the tilt angle of the swashplate 6 tends to increase; when the torque of the variable piston 7 acting on the swashplate 6 is less than the torque of the piston slipper assembly 8 acting on the swashplate 6, the tilt angle of the swashplate 6 tends to decrease.

[0054] The force equation for variable piston 7 is:

[0055] F a =PA (2)

[0056] P is the pilot hydraulic pressure; A is the area of ​​the variable piston 7.

[0057] The equation for the torque acting on the swashplate 6 by the plunger slipper assembly 8 is as follows:

[0058]

[0059] N is the number of plungers; AP P is the area of ​​the plunger; d P is the pump outlet pressure. i The inlet pressure of the pump is r; the radius of the distribution circle is r; M is M. P For the plunger mass; M s α is the shoe mass; α is the swashplate inclination angle; Δφ is the dead angle, see Figure 10 φ represents the high-low voltage span angle, see Figure 10 φ0 is a mismatched angle, see Figure 10 .

[0060] When the control pressure acting on the variable piston 7 stabilizes at a certain value, the swashplate 6 is in a state of force equilibrium. According to formulas (1), (2) and (3), when the outlet pressure increases, the force equilibrium of the swashplate 6 will be broken, and the swashplate 6 will tend to swing. The product of the pressure value that breaks the equilibrium and the flow rate is the constant power value of the pump. This point is the constant power inflection point.

[0061] If it is necessary to reduce the pressure value corresponding to the breaking of the force balance of swashplate 6, the input current of electro-proportional valve 1 can be reduced, and its output pressure oil will also decrease. The output pressure oil of electro-proportional valve 1 acts on valve core 2. When the force on it is less than the spring force of spring 3, the force balance of valve core 2 is broken. Under the push of the spring force, valve core 2 drives eccentric pin 4 to move to the left. The ball head of eccentric pin 4 moves along the U-shaped groove of distribution plate 5, thereby driving distribution plate 5 to rotate, thereby reducing the misalignment angle of distribution plate 5. When the force on valve core 2 reaches balance again, it stops moving, and the misalignment angle of distribution plate 5 is fixed at a certain angle. As can be seen from equation (2), when the torque of variable piston 7 acting on swashplate 6 remains unchanged, in order to maintain the balance of swashplate 6, the torque of plunger slipper assembly 8 acting on swashplate 6 cannot be changed. As can be seen from formula (3), when the mismatch angle decreases, the torque of the plunger slipper assembly 8 acting on the swashplate 6 will increase. Therefore, it is necessary to reduce the pressure value to keep the torque of the plunger on the swashplate 6 constant. The pressure value corresponding to breaking the force balance of the swashplate 6 will also decrease, thus achieving the purpose of reducing the constant power pressure inflection point.

[0062] When it is necessary to increase the pressure value corresponding to breaking the force balance of swashplate 6, the input current of electro-proportional valve 1 is increased, and its output pressure oil also increases accordingly. The pressure oil output by electro-proportional valve 1 acts on valve core 2. When the force on it is greater than the spring force of spring 3, valve core 2 drives eccentric pin 4 to move to the right under the push of pressure oil. The ball head of eccentric pin 4 moves along the U-shaped groove of distribution plate 5, thereby driving distribution plate 5 to rotate, thereby increasing the mismatch angle of distribution plate 5. When the force on valve core 2 reaches balance again, valve core 2 stops moving, and the mismatch angle of distribution plate 5 is fixed at a certain angle. As can be seen from formula (3), the larger the mismatch angle, the smaller the torque of plunger slipper assembly 8 acting on swashplate 6. Therefore, it is necessary to increase the pressure value to keep the torque of plunger slipper assembly 8 on swashplate 6 unchanged, and the pressure value corresponding to breaking the force balance of swashplate 6 will also increase, thus achieving the purpose of increasing the constant power pressure inflection point.

[0063] like Figure 7 As shown, after entering the constant power stage, as the outlet pressure increases, the swashplate 6 swings back to a smaller angle. During the swing of the swashplate 6, it drives the variable piston 7 to move. At this time, the pressure oil in the chamber of the variable piston 7 flows back to the oil tank through the throttle valve 14. When the outlet pressure decreases, the variable piston 7 drives the swashplate 6 to swing to a larger angle. At this time, the variable piston 7 controls the pressure oil to flow partly into the chamber of the variable piston 7 and partly back to the oil tank through the throttle valve 14.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, in the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the accompanying drawings of this invention, the fill patterns are only for distinguishing layers and do not constitute any other limitation.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A valve system with adjustable power, characterized in that, include: The pump housing includes a swashplate (6), a variable piston (7), a plunger slipper assembly (8), a solenoid valve block (9), a housing (10), a pump housing (11), a slider (12), and a pump cylinder (13). It also includes an adjustable power valve assembly comprising an electro-proportional valve (1), a valve core (2), a spring (3), and a distribution plate (5). One end of the valve core (2) is connected to the electro-proportional valve (1) via an oil circuit, and the other end is connected to the spring (3). The valve core (2) is connected to the distribution plate (5) via a transmission structure. The distribution plate (5) is provided with an oil suction groove, an oil discharge groove, and a vibration damping groove surrounding its center. The pressure oil output by the electro-proportional valve (1) acts on the valve core (2) through the oil circuit. When the pressure is greater than that of the spring (3), the pressure oil is applied to the valve core (2). When the force is applied, the valve core (2) drives the distribution plate (5) to rotate through the transmission structure under the push of the pressure oil; the solenoid valve block (9) and the pump housing (11) are respectively connected to the housing (10); the electro-proportional valve (1) is installed on the solenoid valve block (9), and the valve core (2), spring (3) and distribution plate (5) are all installed in the housing (10); the swash plate (6), variable piston (7), slider (12) and pump cylinder (13) are all located in the pump housing (11); the swash plate (6) is connected to the variable piston (7) through the slider (12), the plunger slipper assembly (8) is located in the pump cylinder (13), and the end face of the plunger slipper assembly (8) presses on the swash plate (6); the distribution plate (5) is connected to the pump cylinder (13), and the pump output shaft passes through the swash plate (6); When the control pressure acting on the variable piston (7) stabilizes at a certain value, the swashplate (6) is in a state of force balance. When the outlet pressure increases, the force balance of the swashplate (6) will be broken, and the swashplate (6) will tend to swing. The product of the pressure value that breaks the balance and the flow rate is the constant power value of the pump. This point is the constant power inflection point. If it is necessary to reduce the pressure value corresponding to the force balance of the broken swashplate (6), then reduce the input current of the electro-proportional valve (1), and its output pressure oil will also decrease. The output pressure oil of the electro-proportional valve (1) acts on the valve core (2). When the force on the valve core (2) is less than the spring force of the spring (3), the force balance of the valve core (2) is broken. The valve core (2) is driven by the spring force to drive the distribution plate (5) to rotate through the transmission structure, thereby reducing the misalignment angle of the distribution plate (5). When the force on the valve core (2) reaches balance again, the valve core (2) stops moving, and the distribution... When the disk (5) stops rotating, the mismatch angle of the distribution disk (5) is fixed at a certain angle. When the torque of the variable piston (7) on the swashplate (6) remains unchanged, in order to maintain the balance of the swashplate (6), the torque of the plunger slipper assembly (8) on the swashplate (6) cannot be changed. When the mismatch angle becomes smaller, the torque of the plunger slipper assembly (8) on the swashplate (6) will increase, and the pressure value will decrease to keep the torque of the plunger slipper assembly (8) on the swashplate (6) unchanged. The pressure value corresponding to the force balance of the swashplate (6) will decrease, and the constant power pressure inflection point will decrease.

2. The adjustable power valve system according to claim 1, characterized in that, It also includes a throttle valve (14) for connecting the variable piston (7) and the oil tank.

3. The adjustable power valve system according to claim 1, characterized in that, The transmission structure includes an eccentric pin (4) disposed on the valve core (2) and a U-shaped groove disposed on the distribution plate (5); the eccentric pin (4) includes a ball head and a connecting post, the ball head is located in the U-shaped groove, and the connecting post is connected to the valve core (2).

4. The adjustable power valve system according to claim 1, characterized in that, The transmission structure includes a U-shaped groove in the valve core (2) and an eccentric pin (4) in the distribution plate (5); the eccentric pin (4) includes a ball head and a connecting post, the ball head is connected to the distribution plate (5) through the connecting post, and the ball head is located in the U-shaped groove.

5. The control method for the adjustable power valve system according to claim 1, characterized in that: When it is necessary to increase the pressure value corresponding to breaking the force balance of the swashplate (6), the input current of the electro-proportional valve (1) is increased, and the output pressure oil is also increased accordingly. The output pressure oil of the electro-proportional valve (1) acts on the valve core (2). When the force on the valve core (2) is greater than the spring force of the spring (3), the force balance of the valve core (2) is broken. Under the push of the pressure oil, the valve core (2) drives the distribution plate (5) to rotate through the transmission structure, thereby increasing the mismatch angle of the distribution plate (5). When the force on the valve core (2) reaches balance again, the valve core (2) stops moving, the distribution plate (5) stops rotating, and the mismatch angle of the distribution plate (5) is fixed at a certain angle. As the mismatch angle increases, the torque of the plunger slipper assembly (8) acting on the swashplate (6) decreases, and the pressure value is increased to keep the torque of the plunger slipper assembly (8) on the swashplate (6) unchanged. The pressure value corresponding to breaking the force balance of the swashplate (6) increases, and the constant power pressure inflection point increases.

6. The control method for the adjustable power valve system according to claim 5, characterized in that: After entering the constant power stage, as the pump outlet pressure increases, the swashplate (6) swings back at a small angle. During the swing of the swashplate (6), the variable piston (7) moves. At this time, the pressure oil in the chamber of the variable piston (7) flows back to the oil tank through the throttle valve (14). When the pump outlet pressure decreases, the variable piston (7) drives the swashplate (6) to swing to a large angle. At this time, the variable piston (7) controls a portion of the pressure oil to flow into the chamber of the variable piston (7) and a portion to flow back to the oil tank through the throttle valve (14).

7. The control method for the adjustable power valve system according to claim 1, characterized in that: The torque balance equation for the plunger slipper assembly (8) and swashplate (6) is as follows: (1)； The variable piston (7) is subjected to force; The variable piston (7) is the force arm; The torque exerted by the plunger slipper assembly (8) on the swashplate (6); When the torque of the variable piston (7) acting on the swashplate (6) is greater than the torque of the piston slipper assembly (8) acting on the swashplate (6), the tilt angle of the swashplate (6) tends to increase; when the torque of the variable piston (7) acting on the swashplate (6) is less than the torque of the piston slipper assembly (8) acting on the swashplate (6), the tilt angle of the swashplate (6) tends to decrease. The force equation for the variable piston (7) is: (2)； Pilot fluid pressure; The area of ​​piston (7) is a variable.

8. The control method for the adjustable power valve system according to claim 1, characterized in that: The torque equation of the plunger slipper assembly (8) acting on the swashplate (6) is as follows: (3)； The number of plungers; The area of ​​the plunger; This refers to the pump's outlet pressure. ρ is the pump inlet pressure; r is the radius of the distribution circle; For the plunger mass; For the quality of the ski boots; The swashplate inclination angle; To close the blind spot; For high and low voltage crossover angle; It's a mismatched role.

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