Plunger pump servo cavity adjustable cartridge valve structure, plunger pump and application of plunger pump

Abstract

The invention belongs to the field of performance improvement and optimization of hydraulic plunger pumps, and discloses a plunger pump servo cavity adjustable cartridge valve structure which comprises a cartridge valve body, a valve seat is arranged on the periphery of the cartridge valve body, and the valve seat is in threaded connection with an end cover on the rodless end side of a plunger pump servo plunger. A slidable sliding sleeve is arranged in the valve seat, and one end, positioned in the valve seat, of the sliding sleeve is an open end; an axially adjustable adjusting bolt is arranged at the right end of the cartridge valve, one end of the cartridge valve body is connected with the sliding sleeve, and the other end of the cartridge valve body is in contact with the adjusting bolt; a spring is arranged on the periphery of the cartridge valve body, one end of the spring is connected with the sliding sleeve, and the other end is connected with the adjusting bolt. Through axial adjustment of the adjusting bolt, the force value of the spring is adjusted, and the rigidity of the spring in the center of the servo cavity is adjusted. An adjustable cartridge valve structure is additionally arranged at the rodless end of the servo cavity of the plunger pump, and the spring force value of the cartridge valve is adjusted, so that the same displacement is output, the influence of the spring rigidity on the displacement is reduced, the performance zero position of the servo cavity of the plunger pump is adjustable, and the problem that the output stability of a hydraulic system is poor is solved.

Description

Technical Field

[0001] The invention relates to a plunger pump servo cavity adjustable cartridge valve structure, a plunger pump and applications thereof, and belongs to the field of performance improvement and optimization of hydraulic plunger pumps. Background Art

[0002] At present, most domestic and foreign skid loader manufacturers use two independent travel hydraulic systems to drive the left and right wheels in the design of transmission systems. The speed and torque of the left and right motors are changed by changing the flow of the plunger pump input to the left and right motors, thereby controlling the movement and steering of the vehicle. The advantages of this transmission system are simple structure, small space occupation, and flexible realization of vehicle movement and steering. Its disadvantage is that the straight-line walking ability of the whole machine is not easy to control, and most of the control depends on the operator's familiarity with vehicle control (fine-tuning the swing angle of the left and right handles to make the front and rear pumps of the plunger pump output the same flow to control its straight-line movement). Therefore, the stability of the output flow of the front and rear pumps of the plunger pump determines its walking performance.

[0003] like Figure 1 The figure shows the structure of the existing plunger pump servo chamber. After it is disassembled and tested on the test bench, it is found that the zero position of the structure is adjusted by the rod end of the servo plunger. When the zero position of the plunger pump servo chamber is adjusted, when the front and rear pumps of the plunger pump are driven to output the same displacement, the pressures measured in the rod servo chambers of the front and rear pumps are different. After structural analysis, it is found that the structural zero position of the servo chamber is adjustable, but the performance zero position is not adjustable. The reason is that there is an error in the manufacturing of the center spring stiffness in the servo chamber. When the left and right handles are swung to the same angle to output the same pilot force, the left and right pilot forces enter the front and rear pump rod servo chambers respectively to overcome the center spring to push the servo plunger to move. Because of the manufacturing error of the center spring stiffness, the travel of the front and rear pump servo plungers is different, resulting in different output flow rates of the front and rear pumps, which affects the output torque of the left and right motors. Therefore, when the whole machine walking ability is tested, its travel path will deviate to the end with a smaller plunger stroke, which is the so-called whole machine deviation phenomenon.

[0004] As the demand for skid steer loaders in the domestic market continues to rise, all machine manufacturers pay more and more attention to the performance, quality and reliability of plunger pumps. Improving the performance and stability of loaders and ensuring the reliable performance of plunger pumps have become a powerful factor in the competitiveness of manufacturers. Therefore, it is urgent to design a structure that can compensate for the influence of the spring stiffness error of the servo plunger center and achieve the stability of the output flow of the front and rear pumps of the plunger pump, which plays an important role in improving the performance and stability of loaders and improving product competitiveness. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the central spring stiffness of the plunger pump servo chamber has an error, the servo chamber performance zero position cannot be adjusted, and the hydraulic system output stability is poor. By adding an adjustable cartridge valve to the rodless end of the plunger pump servo chamber, the servo chamber performance zero position can be adjusted, thereby making the hydraulic system output stable.

[0006] To achieve the above-mentioned purpose, as a first aspect, the present invention provides an adjustable cartridge valve structure for a plunger pump servo chamber, characterized in that it includes a cartridge valve body, a valve seat fixed to the end cover on the rodless end side of the servo plunger of the plunger pump is arranged on its outer periphery; the valve seat has an installation cavity, an axially slidable sleeve is arranged in the installation cavity, the end of the sleeve located in the installation cavity is an open end, and the end located outside the installation cavity is a closed end; the cartridge valve body is arranged in the sleeve, one end is fixedly connected to the inner wall of the closed end of the sleeve, and the other end is connected to an axially adjustable adjusting bolt; an elastic component is arranged on the outer periphery of the cartridge valve body, one end of the elastic component is connected to the sleeve, and the other end is connected to the adjusting bolt; the force value of the elastic component is adjusted by axially adjusting the adjusting bolt to realize the regulation of the spring stiffness of the servo chamber center.

[0007] According to the present invention, further, the adjustable bolt has a cavity for installing a spring seat, the cavity is connected to the open end of the sleeve, one end of the spring is connected to the spring seat, and the sleeve is pre-tightened on the valve seat through the spring and the spring seat; one end of the sleeve is a closed end, which extends to the outside of the valve seat; when the servo plunger is adjusted to the middle position, the length of the closed end of the sleeve extending out of the outside of the valve seat coincides with the end face of the rodless end of the servo plunger, at this time the swash plate swing angle is zero, and the plunger pump displacement output is zero.

[0008] According to the present invention, further, the spring stiffness setting value is a servo plunger center spring stiffness error value.

[0009] According to the present invention, further, the valve seat is provided with a through hole leading to the servo cavity to prevent the pressure oil from entering the inner cavity of the valve seat and causing the inner cavity to be pressurized.

[0010] According to the present invention, further, the adjusting bolt is locked with the valve seat through a nut and a screw plug, and the extension degree of the adjustable bolt is changed by rotating the nut.

[0011] According to the present invention, further, a first O-ring is provided on the contact surface between the adjusting bolt and the valve seat to prevent leakage of hydraulic oil.

[0012] According to the present invention, further, the valve seat is connected to the end cover of the plunger pump via an external thread, and a second O-ring is installed on the contact surface of the two to prevent oil leakage at the junction of the two.

[0013] As a second aspect, the present invention further provides a plunger pump, comprising a servo plunger rod end and a servo plunger rodless end, wherein the servo plunger rodless end is provided with the above-mentioned adjustable cartridge valve structure, and the output displacement is adjusted by axial adjustment of the adjustable cartridge valve structure.

[0014] As a third aspect, the present invention also provides an application of the above-mentioned plunger pump. When the output displacements of the servo plunger rod end and the servo plunger rodless end are different, the screw-in depth of the adjusting bolt is adjusted to change the output displacement of that side to make it the same as that of the other side.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The purpose of the present invention is to solve the current problems of errors in the stiffness of the center spring of the servo chamber of the plunger pump, inability to adjust the performance zero position, and poor output stability of the hydraulic system. Compared with the existing plunger pump, the output displacement stability is controlled by the servo plunger center spring, and its uncontrollable factors are large. If the error of the center spring stiffness value of the front and rear pump servo plungers is large, the displacement output error is also large; by adding an adjustable cartridge valve structure to the rodless end of the servo chamber of the plunger pump, adjusting the spring force value of the cartridge valve, and compensating for the different stiffness of the center spring caused by manufacturing errors, the servo plungers of the front and rear pumps of the plunger pump overcome the same spring force value, thereby outputting the same displacement, reducing the influence of the spring stiffness on its displacement, making the performance zero position of the servo chamber of the plunger pump adjustable, and solving the problem of poor output stability of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional schematic diagram of the servo chamber structure of an existing hydraulic plunger pump;

[0018] Figure 2 It is a cross-sectional schematic diagram of a servo chamber structure of a hydraulic plunger pump with a cartridge valve installed;

[0019] Figure 3 It is a schematic cross-sectional view of a cartridge valve structure;

[0020] Figure numerals: 1-cartridge valve body; 2-adjusting bolt; 3-nut; 4-screw plug; 5-first O-ring; 6-valve seat; 7-second O-ring; 8-sleeve; 9-spring; 10-spring seat. DETAILED DESCRIPTION

[0021] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0022] like Figure 2 and 3As shown, the technical solution adopted by the present invention is to provide a plunger pump servo cavity adjustable cartridge valve structure, one end of which is connected to the servo plunger, including a cartridge valve body 1, a valve seat 6 sleeved on the outer periphery of the cartridge valve body 1 and connected to the end cover of the plunger pump servo plunger, a sleeve 8 arranged inside the valve seat 6, an adjusting bolt 2 for adjusting the insertion depth of the cartridge valve body 1, a nut 3 and a plug 4 for locking the adjusting bolt 2, a spring seat 10 arranged in the adjusting bolt 2, a spring 9 connected to the sleeve 8 at one end and the spring seat 10 at the other end, and a first O-ring 5 and a second O-ring 7 that play a sealing role.

[0023] The cartridge valve body 1 is arranged inside the valve seat 6, and is connected to the end cover on the rodless end side of the servo plunger of the plunger pump through the external thread of the valve seat 6; the spring 9 is arranged on the outer periphery of the cartridge valve body 1; an axially slidable sleeve 8 is arranged inside the valve seat 6, one end of the sleeve 8 is a closed end, and the closed end extends to the outside of the valve seat 6, and the end of the sleeve 8 located inside the valve seat 6 is an open end; the cartridge valve body 1 is coaxially arranged in the hollow cavity of the sleeve 8, one end of which is fixedly connected to the inner wall of the closed end of the sleeve 8; the other end of the cartridge valve body 1 is connected to a regulating The adjusting bolt 2 is locked with the valve seat 6 through the nut 3 and the screw plug 4; the tightening degree of the adjusting bolt 2 can be adjusted by rotating the nut 3, thereby adjusting the force value of the spring 9; the adjusting bolt 2 has an installation cavity, in which a spring seat 10 is arranged, and one end of the spring 9 is connected to the spring seat 10 to prevent the spring 9 from swinging when installed; the contact surface between the adjusting bolt 2 and the valve seat 6 is provided with a first O-ring 5 to prevent leakage of hydraulic oil; the sliding sleeve 8 is controlled by the spring 9 and the spring seat 10 so that its closed end extends a fixed length relative to the valve seat 6. When the end face of the servo plunger fits with the protruding end face of the sleeve 8, the servo plunger is located at its neutral position (structural zero position), at which time the swash plate swing angle is zero and the plunger pump displacement output is zero; the spring 9 stiffness setting value is the servo plunger center spring stiffness error value (the difference is set to 8% of the center spring stiffness); a through hole is provided on the valve seat 6 leading to the servo cavity to prevent the pressure oil from entering the inner cavity of the valve seat and causing pressure build-up in the inner cavity; the valve seat 6 is connected to the plunger pump end cover through an external thread, and a second O-ring 7 is installed on the contact surface of the two to prevent oil leakage at the junction of the valve seat and the end cover.

[0024] The working principle of the present invention is as follows: when the servo plungers of the front and rear pumps of the plunger pump are adjusted to the structural zero position, the rodless end face of the servo plunger coincides with the end face of the extended end of the sliding sleeve; the control handle swings, so that the pilot force simultaneously enters the rod ends of the front and rear servo chambers of the plunger pump, and the pressure acts on the rod ends of the servo chambers to overcome the servo plunger center spring and the cartridge valve spring to push the servo plunger to move. When it is found that the displacement of one end of the front and rear pumps is lower (caused by the error in the stiffness values ​​of the two center springs), the output displacement of the front and rear pumps is made the same by adjusting the screwing depth of the adjusting bolt 2 at the low displacement end, that is, at this time, the force value of the servo plunger center spring of the front and rear pumps and the cartridge valve spring after superposition is the same, which solves the problem of large output accuracy error of the hydraulic system.

[0025] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A plunger pump servo chamber adjustable cartridge valve structure, characterized in that: It comprises a cartridge valve body, the periphery of which is provided with a valve seat fixed to the end cover on the rodless end side of the servo plunger of a plunger pump; the valve seat has an installation cavity, the installation cavity is provided with an axially slidable sleeve, the end of the sleeve located in the installation cavity is an open end, and the end located outside the installation cavity is a closed end; the cartridge valve body is arranged in the sleeve, one end is fixedly connected to the inner wall of the closed end of the sleeve, and the other end is connected to an axially adjustable adjusting bolt; an elastic component is arranged on the periphery of the cartridge valve body, one end of the elastic component is connected to the sleeve, and the other end is connected to the adjusting bolt; the force value of the elastic component is adjusted by axially adjusting the adjusting bolt, so as to realize the regulation of the spring stiffness of the center of the servo cavity.

2. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 1, characterized in that: The adjustable bolt has a cavity for installing a spring seat, the cavity is connected to the open end of the sleeve, one end of the elastic component is connected to the spring seat, and the sleeve is arranged in the valve seat through the elastic component and the spring seat; when the servo plunger is adjusted to the middle position, the length of the closed end of the sleeve extending out of the outside of the valve seat coincides with the end face of the rodless end of the servo plunger, at which time the swash plate swing angle is zero and the plunger pump displacement output is zero.

3. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 1, characterized in that: The spring stiffness setting value is a servo plunger center spring stiffness error value.

4. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 1, characterized in that: The valve seat is provided with a through hole leading to the servo cavity to prevent the pressure oil from entering the inner cavity of the valve seat and causing the inner cavity to be pressurized.

5. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 1, characterized in that: The adjusting bolt is locked with the valve seat through a nut and a screw plug, and the expansion and contraction degree of the adjustable bolt can be changed by rotating the nut.

6. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 5, characterized in that: The contact surface between the adjusting bolt and the valve seat is provided with a first O-ring to prevent leakage of hydraulic oil.

7. A plunger pump servo chamber adjustable cartridge valve structure as claimed in claim 1, characterized in that: The valve seat is connected to the end cover of the plunger pump through an external thread, and a second O-ring is installed on the contact surface of the two to prevent oil leakage at the junction of the two.

8. A plunger pump, comprising a servo plunger with a rod end and a servo plunger without a rod end, characterized in that: The rodless end of the servo plunger is provided with an adjustable cartridge valve structure as described in any of claims 1 to 7, and the output displacement is adjusted by axial adjustment of the adjustable cartridge valve structure.

9. Use of the plunger pump as claimed in claim 8, characterized in that: When the output displacements of the servo plunger with rod end and the servo plunger without rod end are different, the screwing depth of the adjusting bolt is adjusted to change the output displacement of the side to be the same as that of the other side.

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