Power control valve block, closed pump assembly and engineering machinery

Abstract

The present invention belongs to the technical field of engineering machinery, and discloses a power control valve block, a closed pump assembly and engineering machinery. The power control valve block includes a pilot valve and a control valve. The pilot valve includes a pilot valve body and a pilot valve core slidably arranged in the pilot valve body. The pilot valve core divides the pilot valve body into a first chamber and a second chamber. At least one of the first chamber and the second chamber is connected to an oil replenishment pump. The pilot valve core is used to control the swing of the swash plate of the variable pump. Control valves are arranged at both ends of the pilot valve. The control valve includes a control valve body and a control valve core slidably matched with the control valve body. The control valve core is partially arranged in the first chamber or the second chamber. When the pilot valve core moves in a direction close to one of the control valve cores, one of the control valve cores can adjust the size of its abutment force against the pilot valve core under the action of hydraulic oil. The power control valve block can be combined with a closed pump without a power control function to form a closed pump assembly with a power control function.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a power control valve block, a closed pump assembly and engineering machinery. Background Art

[0002] Existing closed pumps can only achieve single control, such as manual control, hydraulic pilot control or electric control, and cannot achieve power control. Closed pumps can only be used in certain occasions and machines, and cannot be used in most occasions. Existing closed pump components such as Figure 1 As shown, the oil replenishment pump sucks oil from port B, enters through port F, and reaches the reversing valve 200 and the electric proportional pressure reducing valves MY and MZ respectively. When the electric proportional pressure reducing valve MY is energized, the hydraulic oil pressure on the Y side increases, pushing the pilot valve core 100 to move to the right, thereby driving the reversing valve 200 to move to the right, and the hydraulic oil enters the left chamber of the servo cylinder 300 through the reversing valve 200, pushing the swash plate of the variable pump 400 to swing; conversely, when the electric proportional pressure reducing valve MZ is energized, the hydraulic oil will enter the right chamber of the servo cylinder 300, pushing the swash plate of the variable pump 400 to swing in the opposite direction. The existing pilot stage valve core 100 uses electric proportion to control the flow direction of the hydraulic oil, thereby controlling the swing of the swash plate. However, there is no power control function, and it cannot better adapt to the characteristics of the prime mover, especially the engine, which can easily cause the phenomenon of stalling and flameout. Summary of the invention

[0003] The object of the present invention is to provide a power control valve block having a power control function.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A power control valve block, comprising:

[0006] A pilot valve, comprising a pilot valve body and a pilot valve core slidably disposed in the pilot valve body, wherein the pilot valve core divides the pilot valve body into a first chamber and a second chamber, at least one of the first chamber and the second chamber is communicated with an oil replenishment pump, and the pilot valve core is used to control the swing of a swash plate of a variable displacement pump;

[0007] A control valve is provided at both ends of the pilot valve, the control valve comprises a control valve body and a control valve core slidably matched with the control valve body, the control valve core is partially provided in the first cavity or the second cavity, when the pilot valve core moves toward one of the control valve cores, one of the control valve cores can adjust the size of its abutting force against the pilot valve core under the action of hydraulic oil.

[0008] Preferably, the control valve body is provided with an oil inlet, and the hydraulic oil can flow through the oil inlet and act on the control valve core.

[0009] Preferably, the pilot valve further includes a pilot spring, and the pilot spring is disposed in both the first chamber and the second chamber, one end of the pilot spring is connected to the pilot valve core, and the other end is connected to the first chamber or the second chamber.

[0010] The present invention also provides a closed pump assembly, comprising a variable pump and the power control valve block, wherein the pilot valve core is used to control the rotation of the swash plate of the variable pump.

[0011] Preferably, a transmission assembly is further included, one end of the transmission assembly is connected to the swash plate of the variable pump, and the other end is connected to the pilot valve core, and the pilot valve core drives the swash plate of the variable pump to swing through the transmission assembly.

[0012] Preferably, the transmission assembly includes a reversing valve and a servo cylinder, the reversing valve is connected to the oil replenishing pump, the hydraulic oil enters the servo cylinder through the reversing valve, the servo piston of the servo cylinder is connected to the inclined plate of the variable pump through a driving rod, and the pilot valve core is used to adjust the opening of the reversing valve.

[0013] Preferably, the servo cylinder comprises:

[0014] A servo cylinder, wherein the servo piston is slidably located in the servo cylinder, and the servo piston is connected to the swash plate of the variable pump, and the servo piston divides the servo cylinder into a third chamber and a fourth chamber, and the third chamber and the fourth chamber are both connected to the reversing valve through a pipeline;

[0015] A servo spring is provided in both the third chamber and the fourth chamber, one end of the servo spring abuts against the servo piston, and the other end abuts against the inner wall of the third chamber or the inner wall of the fourth chamber.

[0016] Preferably, the pressure cut-off valve block is further included, and the pressure cut-off valve block includes:

[0017] The shuttle valve comprises two comparison oil ports and one output oil port, wherein the two comparison oil ports are respectively connected to the oil ports at both ends of the variable pump;

[0018] A relief valve, wherein the relief oil inlet of the relief valve is communicated with the oil output port of the shuttle valve, and the relief oil outlet of the relief valve is communicated with the oil pan.

[0019] Preferably, the first chamber of the pilot valve is connected to the oil replenishing pump through a first oil circuit, and the second chamber is connected to the oil replenishing pump through a second oil circuit. The closed pump assembly also includes a first electric proportional pressure reducing valve arranged on the first oil circuit and a second electric proportional pressure reducing valve arranged on the second oil circuit. The first electric proportional pressure reducing valve is used to adjust the opening of the first oil circuit, and the second electric proportional pressure reducing valve is used to adjust the opening of the second oil circuit.

[0020] The present invention also provides an engineering machine, comprising the closed pump assembly.

[0021] Beneficial effects of the present invention:

[0022] The power control valve block provided by the present invention injects hydraulic oil into the first chamber or the second chamber, thereby driving the pilot valve core to slide in the pilot valve body, thereby driving the swash plate of the variable pump to swing. When the pilot valve core moves toward one of the control valves, it abuts against the control valve core of one of the control valves. At the same time, the control valve core of one of the control valves can slide in the control valve body under the action of hydraulic oil, and the size of its abutment against the pilot valve core is adjusted, thereby adjusting the sliding distance of the pilot valve core, thereby adjusting the displacement of the variable pump and adjusting the power of the variable pump. The power control valve block provided by the present invention can be combined with a closed pump without a power control function to form a closed pump assembly with a power control function, thereby reducing the cost of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a closed pump assembly in the prior art;

[0024] Figure 2 is a schematic structural diagram of a closed pump assembly provided by an embodiment of the present invention;

[0025] Figure 3 is a schematic structural diagram of a power control valve block provided by an embodiment of the present invention;

[0026] Figure 4 is a cross-sectional view of a power control valve block provided by an embodiment of the present invention;

[0027] Figure 5 It is a curve diagram showing the relationship between power and displacement of a variable displacement pump provided in an embodiment of the present invention.

[0028] In the figure:

[0029] 100, pilot valve core; 200, reversing valve; 300, servo cylinder; 400, variable pump;

[0030] 1. pilot valve; 11. pilot valve body; 111. first chamber; 112. second chamber; 12. pilot valve core; 13. pilot spring;

[0031] 2. Control valve; 21. Control valve body; 22. Control valve core; 23. Oil inlet;

[0032] 3. Variable displacement pump;

[0033] 4. The first electric proportional pressure reducing valve;

[0034] 5. Second electric proportional pressure reducing valve;

[0035] 6. Directional valve; 7. Servo cylinder;

[0036] 8. Shuttle valve; 9. Overflow valve. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0038] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the embodiments of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0040] In the description of the embodiments of the present invention, the terms "upper", "lower", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0041] This embodiment provides a power control valve block, such as Figures 2 to 5 As shown, the power control valve block includes a pilot valve 1 and a control valve 2. The pilot valve 1 includes a pilot valve body 11 and a pilot valve core 12 slidably arranged in the pilot valve body 11. The pilot valve core 12 divides the pilot valve body 11 into a first chamber 111 and a second chamber 112. At least one of the first chamber 111 and the second chamber 112 is connected to the oil replenishment pump. The pilot valve core 12 is used to control the swash plate swing of the variable pump 3; control valves 2 are arranged at both ends of the pilot valve 1. The control valve 2 includes a control valve body 21 and a control valve core 22 slidably matched with the control valve body 21. The control valve core 22 is partially arranged in the first chamber 111 or the second chamber 112. When the pilot valve core 12 moves in a direction close to one of the control valve cores 22, one of the control valve cores 22 can adjust the size of its abutment force against the pilot valve core 12 under the action of hydraulic oil. Specifically, in this embodiment, the first chamber 111 and the second chamber 112 can be connected to the supplementary oil pump, which is used to supply oil to the first chamber 111 and the second chamber 112. The hydraulic oil flows into the first chamber 111 or the second chamber 112 through the supplementary pump, thereby driving the pilot valve core 12 to slide in the pilot valve body 11. Control valves 2 are provided at both ends of the pilot valve 1. The control valve cores 22 and the first chamber 112 and the second chamber 112 of the two control valves 2 correspond to each other one by one, and pass through the first chamber 111 and the second chamber 112 respectively.

[0042] The power control valve block provided in this embodiment injects hydraulic oil into the first chamber 111 or the second chamber 112, thereby driving the pilot valve core 12 to slide in the pilot valve body 11, thereby driving the swash plate of the variable pump 3 to swing. When the pilot valve core 12 moves toward one of the control valves 2, it abuts against the control valve core 22 of one of the control valves 2. At the same time, the control valve core 22 of one of the control valves 2 can slide in the control valve body 21 under the action of hydraulic oil, and the size of its abutment against the pilot valve core 12 is adjusted, thereby adjusting the sliding distance of the pilot valve core 12, and then adjusting the displacement of the variable pump 3 and the power of the variable pump 3. The power control valve block provided in this embodiment can be combined with a closed pump without a power control function to form a closed pump assembly with a power control function, thereby reducing the cost of the hydraulic system.

[0043] Specifically, Figure 3 and Figure 4As shown, the pilot valve 1 further includes a pilot spring 13. The first chamber 111 and the second chamber 112 are both provided with the pilot spring 13. One end of the pilot spring 13 is connected to the pilot valve core 12, and the other end is connected to the first chamber 111 or the second chamber 112. More specifically, one end of one of the pilot springs 13 is connected to the pilot valve core 12, and the other end is connected to the inner wall of the first chamber 111. One end of the other pilot spring 13 is connected to the pilot valve core 12, and the other end is connected to the inner wall of the second chamber 112. When the pilot valve core 12 slides in the pilot valve body 11, the pilot spring 13 is squeezed and compressed. In this embodiment, the first chamber 111 is located to the left of the pilot piston (such as Figure 2 and Figure 3 The second chamber 112 is located on the right side of the pilot piston (as shown in FIG. Figure 2 and Figure 3 shown on the right).

[0044] Specifically, Figure 3 and Figure 4 As shown, an oil inlet 23 is provided on the control valve body 21, and an annular groove is provided on the control valve core 22, and the annular groove is located between the oil inlet 23 and the first chamber 111 or between the oil inlet 23 and the second chamber 112, and the hydraulic oil can flow into the annular groove through the oil inlet 23 and act on the control valve core 22, thereby adjusting the abutment force of the control valve core 22 against the pilot valve core 12. It should be noted that the hydraulic oil flows in through the oil inlet 23 and flows to the annular groove, which not only adjusts the control valve core 22 to slide along its axial direction and adjusts the abutment force of the control valve core 22 against the pilot valve core 12, but also plays a certain lubricating role. It can be understood that the greater the oil pressure of the hydraulic oil, the greater the abutting force of the control valve core 22 against the pilot valve core 12, the smaller the moving distance of the pilot valve core 12, and the smaller the displacement of the variable pump 3; the smaller the oil pressure of the hydraulic oil, the smaller the abutting force of the control valve core 22 against the pilot valve core 12, the greater the moving distance of the pilot valve core 12, and the larger the displacement of the variable pump 3, thereby realizing power control of the variable pump 3.

[0045] It should be noted that P 先导 *S 先导 -K(X+△X)=P 控制 *S 控制 , that is, the sum of the product of the pilot pressure and the pilot cavity area and the spring compression force is equal to the product of the control pressure and the control cavity area, where the pilot cavity refers to the area of ​​the hydraulic oil acting on the pilot valve core 12, the pilot area is a constant value, the spring stiffness coefficient K is a constant value, X refers to the preset compression of the spring, △X refers to the actual compression of the spring, and the control cavity area refers to the area of ​​the annular groove opened on the control valve core 22. The control cavity area is a constant value. The formula is simplified to: P 控制 *S1-P 先导*S2=K, that is to say, there is a linear relationship between the pilot pressure and the control pressure, that is, there is a linear relationship between the pilot pressure and the hydraulic oil pressure, and the pilot pressure corresponds to the displacement of the variable pump 3, and the displacement multiplied by the fixed speed is the flow rate. Therefore, there is a linear relationship between the flow rate of the variable pump 3 and the control pressure (hydraulic oil pressure).

[0046] like Figure 4 As shown, the black straight line is the relationship curve between the power and displacement of the variable pump 3, the black curve part is the power curve of the engine, and the black dotted line part is the relationship curve between the power and displacement of the variable pump 3 under different currents. The power control valve block can be adjusted to achieve power control of the variable pump 3 so that it is lower than the power curve of the engine, so as to achieve the purpose of not shutting down the engine.

[0047] It should be noted that if Figure 3 As shown, a control cavity is provided on the control valve body 21 of the control valve 2, and the control valve core 22 is partially provided in the control cavity. The first cavity 111 can be communicated with the control cavity of one control valve 2, and the second cavity 112 can be communicated with the control cavity of another control valve 2, so that hydraulic oil is provided in the control cavity, so that both ends of the control valve core 22 have control oil pressure to offset the influence of the pilot oil pressure. More specifically, in this embodiment, an oil passage connecting the first cavity 111 and the control cavity of the control valve 2 is provided on the control valve body 21 of one control valve 2, and an oil passage connecting the second cavity 112 and the control cavity of the control valve 2 is provided on the control valve body 21 of the other control valve 2. In other embodiments, the first cavity 111 and the control cavity of the control valve 2 and the second cavity 112 and the control cavity of the control valve 2 are connected by externally provided oil pipes.

[0048] This embodiment also provides a closed pump assembly, such as Figure 2 and Figure 5 As shown, it includes a variable pump 3 and a power control valve block, and the pilot valve core 12 is used to control the rotation of the swash plate of the variable pump 3, thereby changing the displacement of the variable pump 3 and adjusting the power of the variable pump 3.

[0049] Specifically, Figure 2As shown, the first chamber 111 of the pilot valve 1 is connected to the replenishing pump through the first oil circuit, and the second chamber 112 is connected to the replenishing pump through the second oil circuit. The closed pump assembly also includes a first electric proportional pressure reducing valve 4 arranged on the first oil circuit and a second electric proportional pressure reducing valve 5 arranged on the second oil circuit. The first electric proportional pressure reducing valve 4 is used to adjust the opening of the first oil circuit, and the second electric proportional pressure reducing valve 5 is used to adjust the opening of the second oil circuit. When the first electric proportional pressure reducing valve 4 is opened, the hydraulic oil of the replenishing pump flows to the first chamber 111 of the pilot valve 1 through the first oil circuit, thereby pushing the pilot valve core 12 to move toward the second chamber 112. At this time, the volume of the first chamber 111 increases, and the volume of the second chamber 112 decreases. When the second electric proportional pressure reducing valve 5 is opened, the hydraulic oil of the replenishing pump flows to the second chamber 112 of the pilot valve 1 through the second oil circuit. At this time, the volume of the first chamber 111 decreases, and the volume of the second chamber 112 increases.

[0050] Specifically, Figure 2 As shown, the closed pump assembly also includes a transmission assembly, one end of which is connected to the swash plate of the variable pump 3, and the other end is connected to the pilot valve core 12. The pilot valve core 12 drives the swash plate of the variable pump 3 to swing through the transmission assembly. The transmission assembly includes a reversing valve 6 and a servo cylinder 7. The reversing valve 6 is connected to the oil replenishment pump. The hydraulic oil enters the servo cylinder 7 through the reversing valve 6. The servo piston of the servo cylinder 7 is connected to the swash plate of the variable pump 3 through a driving rod. The pilot valve core 12 is used to adjust the opening of the reversing valve 6. The hydraulic oil provided by the oil replenishment pump enters the servo cylinder 7 through the reversing valve 6. The servo piston of the servo cylinder 7 is connected to the swash plate through a driving rod. The pilot piston is used to control the opening of the reversing valve 6 to adjust the oil pressure of the hydraulic oil entering the servo cylinder 7, thereby adjusting the movement of the servo piston of the servo cylinder 7, and finally realizing the adjustment of the swing angle of the swash plate.

[0051] Specifically, the servo oil cylinder 7 includes a servo cylinder body and a servo spring. The servo piston slides in the servo cylinder body, and the servo piston is connected to the swash plate of the variable pump 3. The servo piston divides the servo cylinder body into a third chamber and a fourth chamber. The third chamber and the fourth chamber are both connected to the reversing valve 6 through a pipeline. The hydraulic oil can flow into the third chamber or the fourth chamber through the reversing valve 6, so that the servo piston slides in the servo cylinder body; a servo spring is arranged in the third chamber and the fourth chamber. One end of the servo spring abuts against the servo piston, and the other end abuts against the inner wall of the third chamber or the inner wall of the fourth chamber. It can be understood that one end of one of the servo springs is connected to the servo piston, and the other end is connected to the inner wall of the third chamber. One end of the other servo spring is connected to the servo piston, and the other end is connected to the inner wall of the fourth chamber. The servo piston can slide in the servo cylinder and squeeze one of the servo pistons. In this embodiment, the third chamber is located to the left of the servo piston (such as Figure 2 The fourth chamber is located on the right side of the servo piston (as shown in Figure 2 right as shown).

[0052] In this embodiment, the reversing valve 6 is a three-position four-way valve, the P port of the reversing valve 6 is connected to the oil replenishing pump, the two working ports of the reversing valve 6 are respectively connected to the third chamber and the fourth chamber, and the T port of the reversing valve 6 is connected to the oil pan. The reversing valve 6 includes a first position (left position), a second position (right position) and a middle position between the first position (left position) and the second position (right position). In this embodiment, the pilot valve core 12 is connected to the reversing valve core of the reversing valve 6 through a transmission rod, and the pilot valve core 12 drives the movement of the reversing valve core through the transmission rod to realize the switching of the reversing valve 6 between the first position (left position), the middle position and the second position (right position). When the reversing valve 6 is in the first position (left position) and the second position (right position), the pumping direction of the variable pump 3 is opposite. When the reversing valve 6 is in the middle position, the swash plate swing angle of the variable pump 3 is 0, and the variable pump 3 stops working.

[0053] It should be noted that when the pressure of the hydraulic oil in the first chamber 111 is greater than the pressure of the hydraulic oil in the second chamber 112, the pilot valve core 12 drives the transmission rod to the right (eg Figure 2 The pilot valve core 12 moves the reversing valve 6 to the first position (left position) and the hydraulic oil provided by the oil replenishment pump enters the third chamber; when the pressure of the hydraulic oil in the second chamber 112 is greater than the pressure of the hydraulic oil in the first chamber 111, the pilot valve core 12 drives the transmission rod to the left (as shown in FIG. Figure 2 The left side as shown in the figure moves and places the reversing valve 6 in the second position (right position), and the hydraulic oil provided by the oil replenishing pump enters the fourth chamber; when the pressure of the hydraulic oil in the first chamber 111 is equal to the pressure of the hydraulic oil in the second chamber 112, the pilot valve core 12 drives the transmission rod to move and places the reversing valve 6 in the middle position, and the third chamber is connected to the fourth chamber. At this time, the servo piston is located in the middle of the two servo springs and drives the swash plate to swing in the direction close to 0.

[0054] Specifically, Figure 2 As shown, the closed pump assembly also includes a pressure cut-off valve block, which includes a shuttle valve 8 and a relief valve 9. The shuttle valve 8 includes two comparison oil ports and one output oil port. The two comparison oil ports are respectively connected to the oil ports at both ends of the variable pump 3; the overflow oil inlet of the relief valve 9 is connected to the output oil port of the shuttle valve 8, and the overflow oil outlet of the relief valve 9 is connected to the oil pan. Through the shuttle valve 8, the highest pressure on both sides of the P / S of the variable pump 3 is selected. When the highest pressure reaches the pressure value set by the relief valve 9, the relief valve 9 opens, and the supplementary oil pressure is discharged into the oil pan, so that the pressure at both ends of the servo valve core is equal, so as to achieve the purpose of the displacement of the variable pump 3 being basically zero. At this time, the pressure of the variable pump 3 is the pressure of the relief valve 9, and the displacement of the variable pump 3 is basically zero, maintaining the existing pressure. In other embodiments, the overflow oil outlet of the relief valve 9 can be connected to the oil tank or the oil collection box.

[0055] This embodiment also provides an engineering machine, including the above-mentioned closed pump assembly, so as to achieve power control.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A power control valve block, characterized in that: include: A pilot valve (1) comprises a pilot valve body (11) and a pilot valve core (12) slidably disposed in the pilot valve body (11), wherein the pilot valve core (12) divides the pilot valve body (11) into a first chamber (111) and a second chamber (112), wherein at least one of the first chamber (111) and the second chamber (112) is connected to an oil replenishment pump, and the pilot valve core (12) is used to control the swash plate swing of a variable displacement pump (3); A control valve (2), wherein both ends of the pilot valve (1) are provided with the control valve (2), the control valve (2) comprising a control valve body (21) and a control valve core (22) slidably matched with the control valve body (21), and the control valve core (22) is partially arranged in the first chamber (111) or the second chamber (112); The oil replenishment pump is used to supply oil to the first chamber (111) and / or the second chamber (112), thereby driving the pilot valve core (12) to slide in the pilot valve body (11); when the pilot valve core (12) moves in a direction close to one of the control valve cores (22), one of the control valve cores (22) can adjust the size of its abutment force against the pilot valve core (12) under the action of hydraulic oil; An oil inlet (23) is provided on the control valve body (21), and an annular groove is provided on the control valve core (22). The annular groove is located between the oil inlet (23) and the first chamber (111) or between the oil inlet (23) and the second chamber (112). The hydraulic oil can flow into the annular groove through the oil inlet (23) and act on the control valve core (22). The greater the oil pressure of the hydraulic oil, the greater the abutment force of the control valve core (22) against the pilot valve core (12), and the smaller the movement distance of the pilot valve core (12).

2. The power control valve block according to claim 1, characterized in that: The pilot valve (1) further comprises a pilot spring (13), wherein the pilot spring (13) is disposed in both the first chamber (111) and the second chamber (112), wherein one end of the pilot spring (13) is connected to the pilot valve core (12), and the other end is connected to the first chamber (111) or the second chamber (112).

3. A closed pump assembly, characterized in that: It comprises a variable pump (3) and a power control valve block as claimed in any one of claims 1 to 2, wherein the pilot valve core (12) is used to control the rotation of the swash plate of the variable pump (3).

4. The closed pump assembly according to claim 3, characterized in that: It also comprises a transmission assembly, one end of which is connected to the swash plate of the variable pump (3), and the other end of which is connected to the pilot valve core (12); the pilot valve core (12) drives the swash plate of the variable pump (3) to swing through the transmission assembly.

5. The closed pump assembly according to claim 4, characterized in that: The transmission assembly comprises a reversing valve (6) and a servo cylinder (7); the reversing valve (6) is connected to an oil replenishing pump; hydraulic oil enters the servo cylinder (7) through the reversing valve (6); the servo piston of the servo cylinder (7) is connected to the swash plate of the variable pump (3) through a driving rod; and the pilot valve core (12) is used to adjust the opening of the reversing valve (6).

6. The closed pump assembly according to claim 5, characterized in that The servo cylinder (7) comprises: A servo cylinder, wherein the servo piston is slidably located in the servo cylinder and connected to the swash plate of the variable pump (3), wherein the servo piston divides the servo cylinder into a third chamber and a fourth chamber, wherein the third chamber and the fourth chamber are both connected to the reversing valve (6) through a pipeline; A servo spring is provided in both the third chamber and the fourth chamber, one end of the servo spring abuts against the servo piston, and the other end abuts against the inner wall of the third chamber or the inner wall of the fourth chamber.

7. The closed pump assembly according to claim 3, characterized in that: Also included is a pressure cut-off valve block, the pressure cut-off valve block comprising: The shuttle valve (8) comprises two comparison oil ports and one output oil port, wherein the two comparison oil ports are respectively connected to the oil ports at both ends of the variable pump (3); A relief valve (9), wherein the relief oil inlet of the relief valve (9) is connected to the oil output port of the shuttle valve (8), and the relief oil outlet of the relief valve (9) is connected to the oil pan.

8. The closed pump assembly according to claim 3, characterized in that: The first chamber (111) of the pilot valve (1) is connected to the oil replenishing pump via a first oil circuit, and the second chamber (112) is connected to the oil replenishing pump via a second oil circuit. The closed pump assembly also includes a first electric proportional pressure reducing valve (4) arranged on the first oil circuit and a second electric proportional pressure reducing valve (5) arranged on the second oil circuit. The first electric proportional pressure reducing valve (4) is used to adjust the opening of the first oil circuit, and the second electric proportional pressure reducing valve (5) is used to adjust the opening of the second oil circuit.

9. An engineering machine, characterized in that: A closed pump assembly comprising any one of claims 3-8.

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