Closed pump variable characteristic curve adjusting structure and adjusting method

Abstract

The invention relates to the technical field of closed pump variable characteristic control, in particular to a closed pump variable characteristic curve adjusting structure and method. The adjusting structure comprises a valve sleeve, a spring set and an adjusting assembly. A valve seat is installed at one end of the valve sleeve, a sealing cavity is formed between the valve seat and the valve sleeve, and a piston is further installed in the valve sleeve in a sliding mode. The spring set is installed in the sealing cavity and comprises a first spring, a second spring and a third spring, the first spring and the second spring are connected in series to form a series spring, the two ends of the series spring abut against the piston and the valve seat respectively, and the third spring is located on the radial inner side of the series spring. The adjusting assembly is installed on the valve seat, and the two ends of the third spring abut against the piston and the adjusting assembly respectively. According to the hydraulic control variable pump, the variable characteristic of the hydraulic control variable pump can be adjusted, and different working conditions of a vehicle or the operation requirements of different operators are met.

Description

Technical Field

[0001] The present invention relates to the technical field of closed pump variable characteristic control, and in particular to a closed pump variable characteristic curve adjustment structure and adjustment method. Background Art

[0002] Hydraulic components are widely used in the industrial field or engineering machinery field, especially in the engineering machinery field, which has high requirements for the variable characteristics of hydraulic pumps. At present, the control methods of hydraulic pumps mainly include manual control, electric control and hydraulic control. Manual control usually changes the variable curve characteristics of the controller through the curve of the cam, while electric control is mostly electric proportional control to provide linear control. In the hydraulic control method, the existing technology usually adopts a single spring or double spring series design. The single spring design provides linear control, that is, the hydraulic pressure is proportional to the displacement of the control piston. The series double spring design provides broken line control. By adjusting the stiffness of the series spring, the slope of the variable curve can be changed.

[0003] Although the single spring design and the double spring series design can provide basic control functions, they cannot achieve the adjustment and change of the variable curve. Although the double spring scheme provides broken line control, the existence of the external power feedback device limits the installation of the adjustment screw, making the variable characteristic unable to be adjusted and only one displacement characteristic can be achieved, which limits the adaptability of the hydraulic pump under different vehicle speed control and different operating requirements. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the embodiments of the present invention is to provide a closed pump variable characteristic curve adjustment structure and adjustment method to solve how to achieve different vehicle speed controls when the motor displacement remains unchanged to meet the operational requirements of different vehicle operating conditions or different operators.

[0005] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A closed pump variable characteristic curve adjustment structure comprises: a valve sleeve, a spring group and an adjustment component; a valve seat is installed at one end of the valve sleeve, a sealing cavity is formed between the valve seat and the valve sleeve, and a piston is also slidably installed in the valve sleeve; the spring group is installed in the sealing cavity, and comprises a first spring, a second spring and a third spring, the first spring and the second spring are connected in series to form a series spring, the two ends of the series spring respectively abut on the piston and the valve seat, and the third spring is located on the radial inner side of the series spring; the adjustment component is installed on the valve seat, and the two ends of the third spring respectively abut on the piston and the adjustment component.

[0007] Optionally, a connecting seat is provided between the first spring and the second spring, one end of the first spring abuts against the piston, and the other end abuts against one end of the connecting seat, and one end of the second spring abuts against the adjusting assembly, and the other end abuts against the other end of the connecting seat.

[0008] Optionally, a step hole is provided in the valve sleeve, and a side of the step hole facing away from the piston has a step surface, and the connecting seat abuts against the step surface.

[0009] Optionally, an inner spring seat is installed at the end of the piston, and one end of the first spring and one end of the third spring abut against the inner spring seat.

[0010] Optionally, the valve seat has a concave hole, an outer spring seat is installed in the concave hole, and one end of the second spring and one end of the third spring abut against the outer spring seat.

[0011] Optionally, the adjusting assembly comprises a valve sleeve and an adjusting nut, the valve sleeve is threadedly installed in the valve seat, one end of the third spring away from the piston abuts against the end of the valve sleeve, and the adjusting nut is installed on the valve sleeve.

[0012] Optionally, the valve sleeve has a threaded hole at its center, a core rod is threadedly installed in the threaded hole, and the core rod passes through the valve sleeve, and a locking nut is installed at the outer end of the core rod.

[0013] Optionally, a shell is provided outside the valve seat, the shell is detachably connected to the valve seat, and the inner end of the shell is sealed to the valve body.

[0014] Optionally, the stiffness coefficient of the first spring is K1, the stiffness coefficient of the second spring is K2, and the stiffness coefficient of the third spring is K3, wherein K1>K2>K3.

[0015] The embodiment of the present invention further provides a method for adjusting the closed pump variable characteristic curve adjustment structure as described above, comprising:

[0016] In the first stage, the sum of the compression forces of the first spring and the third spring is less than the compression force of the second spring, the piston only compresses the first spring and the third spring, and the second spring is preloaded without displacement;

[0017] In the second stage, the sum of the compression forces of the first spring and the third spring is equal to the compression force of the second spring, resulting in an inflection point;

[0018] In the third stage, when the sum of the compression forces of the first spring and the third spring is greater than the compression force of the second spring, the piston compresses the first spring, the second spring and the third spring simultaneously;

[0019] Adjust the preload force of the third spring, thereby adjusting the starting point of the first stage and the compression stroke of the first spring and the third spring when reaching the turning point of the first stage and the second stage, that is, adjust the stroke of the variable piston, and then adjust the variable characteristic curve.

[0020] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] Through the series and parallel relationship of the three springs, two springs are first connected in series, and then connected in parallel with another spring, and the adjustment structure of the parallel spring is added. By adjusting the compression of the third spring, the variable characteristic of the hydraulic variable pump is adjustable, and the initial starting point of the hydraulic pump displacement variable is changed. At the same time, the inflection point force remains unchanged but the corresponding piston stroke is changed, so that the corresponding displacement will change. By changing the variable characteristic curve, different vehicle speed controls can be achieved to meet the needs of different working conditions and operators, which not only improves the control flexibility of the hydraulic pump, but also enhances its adaptability in various application scenarios.

[0022] Advantages of additional aspects of the present invention will be given in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In addition, the spacing or size between each other is exaggerated to show the position of each part, and the schematic diagram is only used for illustration.

[0024] Figure 1 It is a schematic diagram of the variable characteristic curve of the single spring solution;

[0025] Figure 2 It is a schematic diagram of a double spring series structure;

[0026] Figure 3 It is a schematic diagram of the variable characteristic curve of the double spring series scheme;

[0027] Figure 4 is a schematic diagram of a three-spring adjustment structure provided by an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of a variable characteristic curve provided by an embodiment of the present invention;

[0029] In the figure: 1, power feedback device; 2, first spring; 3, second spring; 4, valve body; 5, piston; 6, inner spring seat; 7, connecting seat; 8, outer spring seat; 9, valve seat; 10, housing; 11, third spring; 12, valve sleeve; 13, adjusting nut; 14, locking nut; 15, core rod; DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] Explanation of terms

[0032] Closed pump: usually refers to a closed hydraulic pump, which is a hydraulic pump in which the displacement of the pump and motor is fixed and cannot be changed at will. Closed pump systems are usually used for travel drive control of mobile machinery, such as excavators, cranes, etc. In a closed pump system, the motor displacement remains unchanged, and the speed of the vehicle can be changed by changing the variable characteristics of the pump to achieve control of the equipment speed.

[0033] like Figure 1 As shown, it is the variable characteristic curve of the single spring control mode. The external control hydraulic oil enters the left chamber of the servo variable piston 5, pushing the servo piston 5 to move to the right and compressing the variable spring. At this time, the pressure of the external control oil and the compression displacement of the spring are linearly related, and the control curve is a slant line.

[0034] like Figure 2 As shown, it is a double spring series control mode. The first spring 2 and the second spring 3 are connected in series. The external control hydraulic oil enters the left chamber of the servo variable piston 5, pushing the servo piston 5 to move to the right, first compressing the variable first spring 2, and then compressing the first spring 2 and the second spring 3 at the same time. According to the spring stiffness formula, the stiffness of the first half is K1, and the stiffness of the second half is (K1*K2) / (K1+K2). Since the stiffness of the series spring is lower than K1, the variable curve is a broken line control (such as Figure 3 As shown in the figure, the first half of the variable speed is slow, and the second half of the variable speed is fast. When the hydraulic pump is just variable, only one spring is compressed, and then two springs are compressed. The first half of the control spring has a large stiffness, and the swash plate variable speed is relatively soft and has no impact. The second half of the double spring has a small stiffness, the swash plate variable speed, and the acceleration is faster. Figure 3 As shown, the variable starting point is 4 bar, the pump variable final point is 9.5 bar, and the inflection point of the first spring 2 and the second spring 3 is about 5.5 bar.

[0035] It can be seen that the variable characteristics of the single spring scheme and the double spring series control scheme realize linear control and broken line control, but cannot realize the adjustment and change of the variable curve. In the double spring scheme, there is an external power feedback device 1, and the adjustment screw cannot be installed, and the deformation characteristic cannot be adjusted. The function can only realize one displacement characteristic. When the motor displacement remains unchanged, it is difficult to achieve different vehicle speed control, and it cannot meet the operation requirements of different vehicle working conditions or different operators.

[0036] Example 1

[0037] In order to solve the above technical problems, this embodiment proposes a closed pump variable characteristic curve adjustment structure, which adds a three-spring variable spring scheme on the basis of the double-spring variable mechanism, and at the same time adds an adjustment component of the third spring. While realizing broken line control, it further realizes the adjustment and change of the variable characteristic curve, thereby providing a wider control range and higher operational flexibility.

[0038] like Figure 4 As shown, the closed pump variable characteristic curve adjustment structure includes a valve sleeve 12, a spring group and an adjustment component; a valve seat 9 is installed at one end of the valve sleeve 12, a sealing cavity is formed between the valve seat 9 and the valve sleeve 12, and a piston 5 is also slidably installed in the valve sleeve 12; the spring group is installed in the sealing cavity, including a first spring 2, a second spring 3 and a third spring 11, the first spring 2 and the second spring 3 are connected in series to form a series spring, the two ends of the series spring are respectively abutted on the piston 5 and the valve seat 9, and the third spring 11 is located on the radial inner side of the series spring; the adjustment component is installed on the valve seat 9, and the two ends of the third spring 11 are respectively abutted on the piston 5 and the adjustment component.

[0039] Through the series and parallel relationship of the three springs, two springs are first connected in series, and then connected in parallel with another spring, and the adjustment structure of the parallel spring is added. By adjusting the compression of the third spring 11, the variable characteristic of the hydraulic variable pump is adjustable, and the pump can be made variable from 3bar, 4bar and other pressures. At the same time, the inflection point force remains unchanged but the corresponding piston 5 stroke is changed, so that the corresponding displacement will change. By changing the variable characteristic curve (such as Figure 5 As shown, control curve 1 is a double spring curve, and control curve 2 and control curve 3 can realize different pump variable curves and control characteristics by adjusting the parallel springs to achieve different vehicle speed controls, thereby meeting the needs of different working conditions and operators, which not only improves the control flexibility of the hydraulic pump, but also enhances its adaptability in various application scenarios.

[0040] A connecting seat 7 is provided between the first spring 2 and the second spring 3, one end of the first spring 2 abuts against the piston 5, and the other end abuts against one end of the connecting seat 7, one end of the second spring 3 abuts against the adjustment component, and the other end abuts against the other end of the connecting seat 7. The connecting seat 7 acts as a supporting component between the springs, optimizing the adjustment process of the variable characteristic curve of the entire closed pump.

[0041] The valve sleeve 12 is provided with a stepped hole, and the side of the stepped hole facing away from the piston 5 has a stepped surface, and the connecting seat 7 abuts against the stepped surface. The stepped hole provides a solid supporting surface, so that the connecting seat 7 can abut against the stepped surface reliably, thereby enhancing the connection stability between the piston 5 and the spring assembly.

[0042] An inner spring seat 6 is installed at the end of the piston 5, and one end of the first spring 2 and one end of the third spring 11 abut against the inner spring seat 6. The inner spring seat 6 provides a stable connection point for the first spring 2 and the third spring 11.

[0043] The valve seat 9 has a concave hole, in which an outer spring seat 8 is installed, and one end of the second spring 3 and one end of the third spring 11 abut against the outer spring seat 8. The existence of the outer spring seat 8 can effectively abut one end of the second spring 3 and one end of the third spring 11, thereby improving the stability of the spring group.

[0044] The regulating assembly includes a valve sleeve 12 and an regulating nut 13. The valve sleeve 12 is threadedly mounted in the valve seat 9. One end of the third spring 11 away from the piston 5 abuts against the end of the valve sleeve 12. The regulating nut 13 is mounted on the valve sleeve 12. By adjusting the position of the valve sleeve 12, the pre-compression strength of the third spring 11 can be flexibly adjusted, thereby directly affecting the starting point and inflection point of the variable characteristic curve.

[0045] The center of the valve sleeve 12 has a threaded hole, a core rod 15 is threadedly installed in the threaded hole, and the core rod 15 passes through the valve sleeve 12, and a locking nut 14 is installed at the outer end of the core rod 15. The setting of the core rod 15 can limit the moving position of the piston 5, and the existence of the locking nut 14 can prevent accidental loosening during operation, thereby improving the reliability of the entire structure.

[0046] A housing 10 is disposed outside the valve seat 9, and the housing 10 is detachably connected to the valve seat 9, and the inner end of the housing 10 is sealedly connected to the valve body 4, ensuring that no hydraulic oil leakage occurs during the operation of the pump, thereby improving the working efficiency of the pump.

[0047] The stiffness coefficient of the first spring 2 is K1, the stiffness coefficient of the second spring 3 is K2, and the stiffness coefficient of the third spring 11 is K3, wherein K1>K2>K3. By combining different spring stiffnesses, the response characteristics of the closed pump are optimized so that the hydraulic pump can achieve smoother characteristic changes during the adjustment process to meet the needs under different working conditions.

[0048] Example 2

[0049] This embodiment proposes a method for adjusting the closed pump variable characteristic curve adjustment structure based on the embodiment 1, including:

[0050] The displacement of piston 5 is set to L. According to the formula of spring series and parallel stiffness coefficient:

[0051] In the first stage, when the sum of the compression forces (the sum of F1) of the first spring 2 and the third spring 11 is less than the compression force (F1) of the second spring 3, the piston 5 only compresses the first spring 2 and the third spring 11, and the second spring 3 is pre-tightened without forming any displacement. At this time, the compression force Fa=(K1+K3)*L.

[0052] In the second stage, an inflection point occurs when the sum of the compression forces (the sum of F1 ) of the first spring 2 and the third spring 11 is equal to the compression force ( F1 ) of the second spring 3 .

[0053] In the third stage, when the sum of the compression forces of the first spring 2 and the third spring 11 (the sum of F1) is greater than the compression force (F1) of the second spring 3, the piston 5 compresses the first spring 2, the second spring 3 and the third spring 11 at the same time, and Fb = [(K1*K2) / (K1+K2)+K3]*L.

[0054] Let's take an example to illustrate:

[0055] The F1 value of the first spring 2 is 78N, the F1 value of the second spring 3 is 119N, and the F1 value of the third spring 11 is 20N. When the piston 5 moves to the right:

[0056] Phase 1:

[0057] In the first case, the third spring 11 is not pre-compressed. The piston 5 only pushes the first spring 2. At this time, the variable starting point corresponding stress is 78N, divided by the area of ​​the piston 5, the pilot fluid pressure is about 3bar, at this time, the pump starts to have displacement; in the second case, the third spring 11 is pre-compressed to the F1 value, at this time the area of ​​the piston 5 remains unchanged, the pilot fluid pressure is about 4bar, at this time, the pump starts to have displacement.

[0058] Phase 2:

[0059] The first spring 2 and the third spring 11 are connected in parallel, and the sum of F1 of the first spring 2 and F1 of the third spring 11 is equal to the F1 value of the second spring 3. At this time, the inflection point position is reached.

[0060] Phase 3:

[0061] The three springs work together to achieve maximum displacement.

[0062] Through the above process, it can be known that the spring force at the variable inflection point is 119N, and this value remains unchanged. By adjusting the pre-compression amount of the third spring 11, the spring force value at the initial movement of the piston 5 can be changed, thereby changing the pilot fluid pressure and changing the initial starting point of the hydraulic pump displacement variable. At the same time, since the initial force value of the spring is changed, but the inflection point force value remains unchanged at 119N, the change in the initial force value can change the moving distance of the piston 5, so that the displacement of the piston 5 corresponding to the inflection point position is different, and the displacement of the pump is different. The present invention only adjusts the variable characteristics of the first stage of the pump.

[0063] The present invention changes the displacement adjustment curve by adjusting the third spring 11 to achieve different vehicle speed controls, thereby meeting the operational requirements of different vehicle operating conditions or different operators. If the adjustment is only performed on the basis of two series springs, only the pre-compression of the second spring can be adjusted, thereby adjusting the initial force value of the second spring (for example, from 119N to 200N), and the pre-compression of the first spring cannot be adjusted. At this time, the initial spring force of the piston is still 78N and will not change, that is, the corresponding value of the pump's displacement starting point is always 3bar and will not change. The points that change are the compression of the first spring and the displacement of the piston, that is, adjusting the second spring can only adjust the inflection point force and the displacement of the pump corresponding to the inflection point force, and cannot adjust the pump's starting liquid pressure.

[0064] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A closed pump variable characteristic curve adjustment structure, characterized in that: include: Valve sleeves, spring packs and adjustment assemblies; A valve seat is installed at one end of the valve sleeve, a sealing cavity is formed between the valve seat and the valve sleeve, and a piston is slidably installed in the valve sleeve; The spring group is installed in the sealing cavity, and includes a first spring, a second spring and a third spring. The first spring and the second spring are connected in series to form a series spring. Two ends of the series spring abut against the piston and the valve seat respectively. The third spring is located radially inside the series spring. The regulating assembly is mounted on the valve seat, and two ends of the third spring abut against the piston and the regulating assembly respectively.

2. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: A connecting seat is provided between the first spring and the second spring, one end of the first spring abuts against the piston, and the other end abuts against one end of the connecting seat, one end of the second spring abuts against the adjusting assembly, and the other end abuts against the other end of the connecting seat.

3. The closed pump variable characteristic curve adjustment structure according to claim 2, characterized in that: A step hole is arranged in the valve sleeve, and a side of the step hole facing away from the piston has a step surface, and the connecting seat abuts against the step surface.

4. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: An inner spring seat is installed at the end of the piston, and one end of the first spring and one end of the third spring abut against the inner spring seat.

5. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: The valve seat has a concave hole, an outer spring seat is installed in the concave hole, and one end of the second spring and one end of the third spring abut against the outer spring seat.

6. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: The regulating assembly comprises a valve sleeve and an regulating nut. The valve sleeve is threadedly installed in the valve seat. One end of the third spring away from the piston abuts against the end of the valve sleeve. The regulating nut is installed on the valve sleeve.

7. The closed pump variable characteristic curve adjustment structure according to claim 6, characterized in that: The center of the valve sleeve is provided with a threaded hole, a core rod is threadedly installed in the threaded hole, and the core rod passes through the valve sleeve, and a locking nut is installed at the outer end of the core rod.

8. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: A shell is arranged outside the valve seat, the shell is detachably connected to the valve seat, and the inner end of the shell is sealedly connected to the valve body.

9. The closed pump variable characteristic curve adjustment structure according to claim 1, characterized in that: The stiffness coefficient of the first spring is K1, the stiffness coefficient of the second spring is K2, and the stiffness coefficient of the third spring is K3, wherein K1>K2>K3.

10. A method for adjusting a closed pump variable characteristic curve adjustment structure according to any one of claims 1 to 9, characterized in that: include: In the first stage, the sum of the compression forces of the first spring and the third spring is smaller than the compression force of the second spring, the piston only compresses the first spring and the third spring, and the second spring is preloaded without displacement; In the second stage, the sum of the compression forces of the first spring and the third spring is equal to the compression force of the second spring, resulting in an inflection point; In the third stage, when the sum of the compression forces of the first spring and the third spring is greater than the compression force of the second spring, the piston compresses the first spring, the second spring and the third spring simultaneously; Adjust the preload force of the third spring, thereby adjusting the starting point of the first stage and the compression stroke of the first spring and the third spring when reaching the turning point of the first stage and the second stage, that is, adjust the stroke of the variable piston, and then adjust the variable characteristic curve.

Images