Plunger pump servo cavity adjustable cartridge valve structure

Abstract

The utility model 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 utility model relates to a kind of adjustable plug-in valve structure of plunger pump servo cavity, belong to the field of hydraulic plunger pump performance improvement, optimization. BACKGROUND

[0002] At present, the transmission system design of domestic and foreign skid steer loader manufacturers mostly adopts two independent walking hydraulic systems to drive left and right wheels, changes the speed and torque of left and right motors by changing the flow of plunger pump input left and right motors, to control the walking and steering of vehicle. The advantages of this transmission system are simple structure, small space occupation, and flexible realization of vehicle walking and steering. Its disadvantage is that the straight-line walking ability of the whole machine is not easy to control, mostly relying on the familiarity of the operator to control the walking ability of the vehicle (fine-tuning left and right handle swing angle to make the plunger pump front and rear pump output the same flow to control its straight-line walking), so the stability of plunger pump front and rear pump output flow determines its walking performance.

[0003] As shown in Figure 1 The structure zero of the existing plunger pump servo cavity structure is adjusted by the rod end of servo plunger. When the plunger pump servo cavity zero is set, the pressures measured in the front and rear pump rod servo cavities are different when the front and rear pumps output the same displacement. After analyzing the structure, it is found that the structure zero of the servo cavity is adjustable, but the performance zero is not adjustable. The reason is that there is an error in the manufacturing of the center spring stiffness in the servo cavity. When the left and right handles swing the same angle to output the same pilot force, the left and right pilot forces enter the front and rear pump rod servo cavities to overcome the center spring to move the servo plunger. Because of the error in the manufacturing of the center spring stiffness, the strokes of the front and rear pump servo plungers are different, resulting in different output flows of the front and rear pumps, which affects the output torque of the left and right motors, so that the driving path of the whole machine will be biased to the end with smaller plunger stroke during the walking ability test of the whole machine, which is called the whole machine running deviation.

[0004] With the increasing demand for skid steer loaders in the domestic market, manufacturers pay more attention to the performance, quality and reliability of plunger pumps. Improving the performance and stability of the loader and ensuring the performance and reliability of the plunger pump 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 center spring stiffness error of the servo plunger, realize the stability of the output flow of the front and rear pumps of the plunger pump, and play an important role in improving the performance and stability of the loader and improving the competitiveness of the product. UTILITY MODEL CONTENTS

[0005] The utility model discloses a purpose is to solve the current plunger pump servo cavity center spring rigidity error, servo cavity performance zero position can not be adjusted, the problem of poor output stability of hydraulic system. Through being newly added one adjustable cartridge valve at the rodless end of plunger pump servo cavity, can realize the adjustment of servo cavity performance zero position, thereby make the output stability characteristic of hydraulic system.

[0006] In order to achieve the above object, the utility model provides a kind of plunger pump servo cavity adjustable cartridge valve structure, including cartridge valve body, its outer periphery is provided with the valve seat fixed with the end cover of the rodless end side of plunger pump servo plunger;Valve seat has installation cavity, the installation cavity is equipped with the sliding sleeve that can axially slide, and one end of sliding sleeve in installation cavity is open end, and one end outside installation cavity is closed end;Cartridge valve body is located in the sliding sleeve, one end is fixedly connected with the closed end inner wall of the sliding sleeve, and the other end is connected with the adjustable adjusting bolt that can be axially adjusted;Cartridge valve body outer periphery is provided with spring, and one end of spring is connected with sliding sleeve, and the other end is connected with adjusting bolt;By adjusting bolt axial adjustment, adjust spring force value, realize the control of servo cavity center spring rigidity.

[0007] According to the utility model, further, the adjustable bolt has the cavity for installing spring seat, the cavity is communicated with the open end of the sliding sleeve, one end of the spring is connected with the spring seat, and the sliding sleeve is pre-pressed on the valve seat by the spring and the spring seat;One end of the sliding sleeve is closed end, and the end extends to the outside of the valve seat;When servo plunger is adjusted to the middle position, the length of the closed end of the sliding sleeve extending outside the valve seat coincides with the rodless end face of servo plunger, at this time, the swash plate swing angle is zero, and the plunger pump displacement output is zero.

[0008] According to the utility model, further, the spring rigidity set value is servo plunger center spring rigidity error value.

[0009] According to the utility model, further, the valve seat is provided with through hole leading to servo cavity, prevents pressure oil from entering the inner chamber of valve seat and causes the inner chamber to be blocked.

[0010] According to the utility model, further, the adjusting bolt is locked with the valve seat by nut and screw plug, and the telescopic degree of adjustable bolt is changed by rotating nut.

[0011] According to the utility model, further, the contact surface of the adjusting bolt and the valve seat is provided with first O-shaped ring, to prevent hydraulic oil leakage.

[0012] According to the utility model, further, the valve seat is connected with plunger pump end cover by external thread, and second O-shaped ring is mounted on the contact surface of the two, to prevent oil leakage at the joint of the two.

[0013] Compared with prior art, the utility model has the following beneficial effects:

[0014] The utility model discloses a kind of adjustable cartridge valve structures of plunger pump servo cavity, one end is connected with servo plunger, including cartridge valve body 1, the valve seat 6 of being sleeved in the outer periphery of cartridge valve body 1 and being connected with plunger pump servo plunger end cover, the sliding sleeve 8 being arranged in valve seat 6 interior, the adjusting bolt 2 for adjusting the insertion depth of cartridge valve body 1, the nut 3 and the plug 4 for locking adjusting bolt 2, the spring seat 10 being arranged in adjusting bolt 2 and the spring 9 with one end being connected with sliding sleeve 8, the other end being connected with spring seat 10, the first O-ring 5 and the second O-ring 7 playing sealing effect. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a hydraulic plunger pump servo cavity structure sectional view of existing;

[0016] Figure 2 It is a hydraulic plunger pump servo cavity structure sectional view of existing;

[0017] Figure 3 It is a hydraulic plunger pump servo cavity structure sectional view of existing;

[0018] Reference signs: 1-cartridge valve body;2-adjusting bolt;3-nut;4-plug;5-first O-ring;6-valve seat;7-second O-ring;8-sliding sleeve;9-spring;10-spring seat. DETAILED DESCRIPTION

[0019] To make the utility model more obvious and easy to understand, with preferred embodiment, and cooperate with the drawings, detailed description is as follows.

[0020] As Figure 2 And 3 The utility model discloses a kind of adjustable cartridge valve structures of plunger pump servo cavity, one end is connected with servo plunger, including cartridge valve body 1, the valve seat 6 of being sleeved in the outer periphery of cartridge valve body 1 and being connected with plunger pump servo plunger end cover, the sliding sleeve 8 being arranged in valve seat 6 interior, the adjusting bolt 2 for adjusting the insertion depth of cartridge valve body 1, the nut 3 and the plug 4 for locking adjusting bolt 2, the spring seat 10 being arranged in adjusting bolt 2 and the spring 9 with one end being connected with sliding sleeve 8, the other end being connected with spring seat 10, the first O-ring 5 and the second O-ring 7 playing sealing effect.

[0021] The plug-in valve body 1 is arranged inside the valve seat 6, and is connected with the end cover of the rodless end side of the plunger pump servo plunger through the external thread of the valve seat 6; the spring 9 is arranged on the outer periphery of the plug-in valve body 1; the valve seat 6 is internally provided with a sliding sleeve 8 which can axially slide, one end of the sliding sleeve 8 is a closed end which extends to the outside of the valve seat 6, and the other end of the sliding sleeve 8 in the valve seat 6 is an open end; the plug-in valve body 1 is coaxially arranged in the hollow cavity of the sliding sleeve 8, and one end of the plug-in valve body 1 is fixedly connected with the inner wall of the closed end of the sliding sleeve 8; the other end of the plug-in valve body 1 is connected with the adjusting bolt 2, the adjusting bolt 2 is locked with the valve seat 6 through the nut 3 and the plug 4; the nut 3 is rotated to adjust the tightening degree of the adjusting bolt 2, so as to adjust the force value of the spring 9; the adjusting bolt 2 is provided with a mounting cavity, the mounting cavity is provided with a spring seat 10, one end of the spring 9 is connected with the spring seat 10, so as to prevent the spring 9 from being deflected during installation; the contact surface between the adjusting bolt 2 and the valve seat 6 is provided with the first O-shaped ring 5, so as to prevent hydraulic oil from leaking; the sliding sleeve 8 is controlled by the spring 9 and the spring seat 10, so that the closed end of the sliding sleeve 8 extends by a fixed length relative to the valve seat 6. When the end face of the servo plunger is attached to the end face of the sliding sleeve 8, the servo plunger is located at the middle position (structure zero position), at this time, the swash plate angle is zero, and the plunger pump displacement output is zero; the rigidity setting value of the spring 9 is the servo plunger center spring rigidity error value (the difference value is set as 8% of the center spring rigidity); the valve seat 6 is provided with a through hole leading to the servo cavity, so as to prevent the pressure oil from entering the inner cavity of the valve seat and causing the inner cavity to be blocked; the valve seat 6 is connected with the end cover of the plunger pump through the external thread, and the second O-shaped ring 7 is arranged on the contact surface between the valve seat 6 and the end cover, so as to prevent oil leakage at the joint between the valve seat and the end cover.

[0022] The working principle of the utility model is as follows: when the front and rear pump servo plungers of the plunger pump are adjusted to the structure zero position, the rodless end face of the servo plunger is coincided with the extended end face of the sliding sleeve; the control handle is swung, so that the pilot force is simultaneously introduced into the rod end of the front and rear servo cavities of the plunger pump, the pressure acting on the rod end of the servo cavity overcomes the servo plunger center spring and the plug-in valve spring to push the servo plunger to move; when it is found that one end of the front and rear pumps has a lower displacement (caused by the two center spring rigidity value errors), the rotation depth of the low displacement end adjusting bolt 2 is adjusted, so that the output displacements of the front and rear pumps are the same, that is, at this time, the force values of the servo plunger center springs and the plug-in valve springs of the front and rear pumps after superposition are the same, so the problem of large output precision error of the hydraulic system is solved.

[0023] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form or in essence. It should be noted that those skilled in the art can make some improvements and supplements without departing from the present application, and these improvements and supplements should also be considered as the protection scope of the present application. Any equivalent changes, modifications and evolutions made by those skilled in the art without departing from the spirit and scope of the present application, and all equivalent embodiments of the present application, are still within the scope of the technical solutions of the present application.

Claims

1. A plunger pump servo chamber adjustable cartridge valve structure, characterized in that, The plug-in valve body is provided with a valve seat fixed with an end cover on the rodless end side of the plunger servo plunger of the plunger pump; the valve seat has a mounting cavity, and an axially slidable sleeve is arranged in the mounting cavity; one end of the sleeve in the mounting cavity is an open end, and the other end of the sleeve out of the mounting cavity is a closed end; the plug-in valve body is arranged in the sleeve, one end of the plug-in valve body is fixedly connected with the inner wall of the closed end of the sleeve, and the other end of the plug-in valve body is connected with an axially adjustable adjusting bolt; a spring is arranged on the outer periphery of the plug-in valve body, one end of the spring is connected with the sleeve, and the other end of the spring is connected with the adjusting bolt; the spring force value is adjusted by adjusting the adjusting bolt in the axial direction, so that the center spring stiffness of the servo cavity is adjusted and controlled.

2. An adjustable cartridge valve structure for a plunger pump servo chamber as defined in claim 1, wherein, The adjustable bolt has a cavity for mounting a spring seat, the cavity is in communication with the open end of the sleeve, one end of the spring is connected with the spring seat, and the sleeve is arranged on the valve seat through the spring 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 this time, the swash plate swing angle is zero, and the plunger pump displacement output is zero.

3. A plug valve structure for an adjustable cartridge valve of a plunger pump servo chamber as defined in claim 1, wherein, The spring stiffness set value is the servo plunger center spring stiffness error value.

4. A plug valve structure for an adjustable cartridge valve of a piston pump servo chamber as defined in claim 1, characterized in that The valve seat is provided with a through hole leading to the servo cavity, so as to prevent the pressure oil from entering the inner cavity of the valve seat and causing the inner cavity to be blocked.

5. An adjustable cartridge valve structure for a plunger pump servo chamber as defined in claim 1 wherein, The adjusting bolt is locked with the valve seat through a nut and a plug, and the extension degree of the adjustable bolt is changed by rotating the nut.

6. An adjustable cartridge valve structure for a plunger pump servo chamber as defined in claim 5 wherein, The contact surface of the adjusting bolt and the valve seat is provided with a first O-shaped ring, so as to prevent hydraulic oil from leaking.

7. An adjustable cartridge valve structure for a plunger pump servo chamber as defined in claim 1 wherein, The valve seat is connected with the end cover of the plunger pump through external threads, and a second O-shaped ring is arranged on the contact surface of the two, so as to prevent oil leakage at the joint of the two.

Images