Axial plunger pump with vibration reduction and gap self-adaptive adjustment functions

Abstract

The invention provides an axial plunger pump with vibration reduction and clearance self-adaptive adjustment functions, which comprises a plunger cylinder body assembly, and the plunger cylinder body assembly is composed of a plunger, a cylinder body, magnetorheological fluid, a permanent magnet plunger barrel and a plunger hole; a cavity is formed between the inner wall and the outer wall of the plunger, the cavity is filled with the magnetorheological fluid, and the magnetorheological fluid can freely flow in the cavity; under the action of external magnetic force, the magnetorheological fluid has a chain structure; the plunger holes are formed in the cylinder body in a circumferential surrounding manner, and the plunger holes are used for accommodating the permanent magnet plunger barrel and the plunger; the permanent magnet plunger barrel is detachably fixed on the cylinder body; the plunger is embedded into the permanent magnet plunger barrel, and the permanent magnet plunger barrel is in clearance fit with the plunger; by arranging the plunger, the permanent magnet plunger barrel and the magnetorheological fluid, the viscosity of the magnetorheological fluid is changed under the action of a magnetic field to increase damping force, meanwhile, the magnetorheological fluid flows to enable the plunger to adjust the gap between the plunger and the cylinder body in a self-adaptive mode, and eccentric wear is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of plunger pumps, and in particular to an axial plunger pump with vibration reduction and clearance adaptive adjustment functions. Background Art

[0002] As one of the common hydraulic components in hydraulic systems, axial piston pumps are widely used in engineering machinery, aerospace, shipbuilding, metallurgy and other fields. During the operation of traditional axial piston pumps, due to the high movement speed of the plunger and cylinder assembly, vibration and noise often occur, which seriously affects the working stability and life of the pump. Especially under high pressure and high speed conditions, the friction, impact and uneven clearance between the plunger and the cylinder body can easily lead to increased wear of the components, resulting in unnecessary energy loss. In addition, the clearance between the plunger and the cylinder body will deviate after long-term use, reducing the efficiency and service life of the pump.

[0003] In view of the above problems, the prior art usually adopts methods such as adding damping devices or optimizing the plunger-cylinder clearance design to achieve vibration reduction, noise reduction and leakage control. For example, a spring or viscous damper can be added between the plunger and the cylinder to absorb vibration energy by using its damping characteristics; or the gap size between the plunger and the cylinder can be adjusted through precision machining to reduce leakage. However, these methods are often complex in structure, with high manufacturing costs, and have limited improvement on the working stability and service life of the pump. Therefore, there is an urgent need for a new type of axial piston pump plunger-cylinder assembly that can achieve vibration reduction, noise reduction and adaptive clearance adjustment while maintaining a simple and reliable structure, thereby comprehensively improving the working performance and service life of the axial piston pump and meeting the increasingly stringent market demands. Summary of the invention

[0004] The object of the present invention is to provide an axial piston pump with vibration reduction and clearance adaptive adjustment functions, so as to solve the problems of large vibration noise and severe eccentric wear of the piston in the prior art.

[0005] In order to solve the above technical problems, the present invention provides an axial piston pump with vibration reduction and clearance adaptive adjustment functions, including a piston-cylinder assembly, which is composed of a plunger, a cylinder, a magnetorheological fluid, a permanent magnetic plunger cylinder and a plunger hole;

[0006] A cavity is provided between the inner and outer walls of the plunger, and the magnetorheological fluid fills the cavity and can flow freely in the cavity; under the action of an external magnetic force, the magnetorheological fluid has a chain structure;

[0007] The plunger hole is arranged in a circular manner inside the cylinder body, and the plunger hole is used to accommodate the permanent magnetic plunger barrel and the plunger; the permanent magnetic plunger barrel is detachably fixed on the cylinder body; the plunger is embedded in the permanent magnetic plunger barrel, and the permanent magnetic plunger barrel and the plunger are clearance-fitted.

[0008] In a preferred embodiment, the cavity is arranged around the axis of the plunger; the cavity is a closed cavity.

[0009] In a preferred embodiment, a small hole is provided on the outer wall of the plunger, and the small hole has sealing properties;

[0010] The magnetorheological fluid enters the cavity through the small hole.

[0011] In a preferred embodiment, the permanent magnetic plunger barrel is detachably fixed to the plunger hole via a slot.

[0012] In a preferred embodiment, the permanent magnetic plunger barrel is made of a material with strong wear resistance; the plunger is in contact with the permanent magnetic plunger barrel.

[0013] In a preferred embodiment, the permanent magnetic plunger cylinder is made of permanent magnetic material.

[0014] In a preferred embodiment, an oil film is provided on the inner wall of the permanent magnetic plunger cylinder, and the oil film is in contact with the plunger.

[0015] In a preferred embodiment, the magnetorheological fluid consists of magnetic particles and a carrier liquid.

[0016] In a preferred embodiment, the magnetic particles are made of ferromagnetic materials, including iron, cobalt, and nickel; and the carrier liquid is low-viscosity mineral oil or silicone oil.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0018] 1. By filling the cavity on the inner wall of the plunger with magnetorheological fluids of different viscosities, the magnetorheological fluid changes its viscosity under the action of the magnetic field, effectively increasing the damping force, thereby reducing the vibration and noise caused by the movement of the plunger, and effectively solving the problem of high vibration and noise in the prior art.

[0019] 2. By filling the cavity on the inner wall of the plunger with magnetorheological fluid, the plunger can adaptively adjust the gap between the plunger and the cylinder body under the action of the magnetic field force, keep the axis of the plunger and the cylinder body consistent, avoid eccentric wear, reduce leakage, and effectively solve the serious eccentric wear problem of the plunger in the prior art.

[0020] 3. By embedding a permanent magnetic plunger barrel in the plunger hole inside the cylinder body, the plunger is in contact with the permanent magnetic plunger barrel, and the plunger does not directly contact the cylinder body with friction, thereby preventing the cylinder body from being worn and protecting the cylinder body. The permanent magnetic plunger barrel is detachable and when the permanent magnetic plunger barrel is worn, only the permanent magnetic plunger barrel needs to be replaced or repaired, thereby reducing the cost of repair and replacement.

[0021] 4. By setting up the plunger, permanent magnetic plunger cylinder and magnetorheological fluid, the working stability and service life of the plunger pump are significantly improved, and the structure is simple and reliable, suitable for various axial piston pumps, and has broad application prospects and market value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of an axial piston pump in a preferred embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the plunger structure of an axial piston pump in a preferred embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the cylinder structure of an axial piston pump in a preferred embodiment of the present invention;

[0025] Figure 4 A comparison diagram of the vibration amplitude of the axial piston pump in the preferred embodiment of the present invention and the vibration amplitude of the existing piston pump;

[0026] Figure 5 A comparison diagram of the amplitude and speed of the axial piston pump in the preferred embodiment of the present invention and the existing piston pump;

[0027] Figure 6 A schematic diagram of the force on the plunger of an axial piston pump in a preferred embodiment of the present invention;

[0028] Figure 7 The figure is a curve showing the variation of the lateral force between the plunger and the plunger hole wall of the axial piston pump in the preferred embodiment of the present invention.

[0029] Explanation of the accompanying reference numerals: 1. plunger; 2. cylinder body; 3. magnetorheological fluid; 4. permanent magnetic plunger cylinder; 5. plunger hole. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted 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 components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] refer to Figure 1-Figure 7 This embodiment provides an axial piston pump 1 with vibration reduction and clearance adaptive adjustment functions, including a piston cylinder assembly. Figure 1 The plunger-cylinder assembly is composed of a plunger 1, a cylinder 2, a magnetorheological fluid 3, a permanent magnetic plunger barrel 4 and a plunger hole 5. A cavity is provided between the inner and outer walls of the plunger 1, and the magnetorheological fluid 3 fills the cavity and can flow freely inside the cavity; the plunger hole 5 is arranged in a circular manner inside the cylinder 2 to accommodate the permanent magnetic plunger barrel 4 and the plunger 1; the permanent magnetic plunger barrel 4 is fixed inside the cylinder 2 through a slot to provide a stable external magnetic field to the magnetorheological fluid 3. By filling the inner wall cavity of the plunger 1 with magnetorheological fluids 3 of different viscosities and embedding the permanent magnetic plunger barrel 4 in the plunger hole 5 inside the cylinder 2, the magnetorheological fluid 3 reduces the vibration of the plunger 1 through the damping effect under the action of the magnetic field, and at the same time, the plunger 1 adaptively adjusts the gap between the plunger 1 and the cylinder 2 under the action of the magnetic field force, keeps the axes of the plunger 1 and the cylinder 2 consistent, avoids eccentric wear, and reduces leakage.

[0034] like Figure 2 A closed cavity surrounding the axis is provided between the inner and outer walls of the plunger 1 to place the magnetorheological fluid 3. At the same time, a small hole with good sealing performance is provided on the outer wall of the plunger 1 to replace different magnetorheological fluids 3. The magnetorheological fluid 3 enters the cavity through the small hole.

[0035] like Figure 3 The permanent magnetic plunger barrel 4 is detachably fixed to the plunger hole 5 through a slot, and the permanent magnetic plunger barrel 4 is fixed to the plunger hole 5 on the inner wall of the cylinder body 2 through the slot, and can be easily replaced with a permanent magnetic plunger barrel 4 with different magnetic field strengths.

[0036] The permanent magnetic plunger barrel 4 is made of a material with strong wear resistance. The plunger 1 does not directly contact the cylinder body 2 with friction, but only directly contacts the permanent magnetic plunger barrel 4, which effectively prevents the cylinder body 2 from being worn. When the permanent magnetic plunger barrel 4 is worn, only the plunger barrel needs to be replaced or repaired, which reduces costs.

[0037] The permanent magnetic plunger barrel 4 is placed in the plunger hole 5 and contacts the plunger 11 through an oil film to provide a stable external magnetic field to the magnetorheological fluid 3 inside the plunger 1. The permanent magnetic plunger barrel 4 and the plunger 1 are clearance-fitted, and the oil film formed between the two can further reduce wear.

[0038] Specifically, the principle of achieving vibration reduction and noise reduction by the plunger-cylinder assembly in this embodiment is as follows:

[0039] like Figure 4 The magnetorheological fluid 3 provided in this embodiment is composed of magnetic particles and a carrier liquid. The magnetic particles are usually made of strong magnetic materials such as iron, cobalt, nickel, etc., and have a micron size. The carrier liquid is selected from mineral oil or silicone oil with low viscosity. Under the action of an external magnetic field, the magnetic particles will form a chain structure, increase the viscosity and strength of the magnetorheological fluid 3, and thus produce a damping effect. When the plunger 1 vibrates during operation, the magnetorheological fluid 3 will be affected by the external magnetic field in the cavity of the inner wall of the plunger 1, forming a chain structure, increasing its viscosity and strength. This damping effect can effectively absorb and dissipate the vibration energy of the plunger 1, thereby reducing the vibration amplitude and achieving a reduction in the vibration amplitude of the axial piston 1 pump.

[0040] When there is no magnetic field, the magnetorheological fluid 3 is in a liquid state, the damping force is small, the system's vibration damping is weak, and the fluid in the plunger 1 can allow a wider range of movement. When there is a magnetic field, the magnetic particles are arranged into a chain structure under the action of the magnetic field, the liquid behaves as a quasi-solid state, and the damping force is greatly enhanced. At this time, the damping effect of the system becomes stronger, and the vibration is quickly suppressed. Therefore, by adjusting the magnetic field strength, the response of the system vibration can be weakened.

[0041] The mechanical properties of magnetorheological fluids are often described by the Bigham model, which describes the relationship between stress and strain rate under shear force:

[0042]

[0043] Where: τ is the shear stress in the fluid; τ y (H) is the yield stress; η is the plastic viscosity; is the shear rate. The relationship between yield stress and magnetic field strength is:

[0044] τ y (H)=αHβ (2)

[0045] Among them, α and β are empirical coefficients.

[0046] The damping force of the magnetorheological damper is:

[0047]

[0048] Where: F is the total damping force, C is the viscous damping coefficient, is the velocity of the liquid in plunger 1, F f is the controllable friction force (related to the magnetic field strength), and sgn() is the sign function.

[0049] When the external magnetic field changes, the value of C will change, thereby changing the damping force of the system and achieving the effect of vibration control.

[0050] like Figure 5 Compared with the existing plunger pump, it can be seen that the vibration velocity amplitude of the plunger using the device of the present invention is greatly reduced compared with the traditional plunger, and the vibration reduction effect is very obvious.

[0051] Specifically, the principle of the plunger-cylinder assembly in this embodiment to achieve the adaptive adjustment of the plunger-cylinder clearance is as follows:

[0052] like Figure 6 The main forces on which the plunger is subjected during movement are: the gravity of the plunger group F g , plunger chamber oil pressure F p , Axial inertia force of plunger group F a , Plunger group centrifugal force F c , the reaction force F of the swash plate on the plunger group N , Cylinder cavity oil pressure F u , the lateral forces F1 and F2 between the plunger and the wall of the plunger hole 5 and the friction force F generated by F1 and F2 f , the friction force F between the sliding shoe and the swash plate b , the return force F of the return plate acting on the sliding shoe during the oil suction stroke r Point C is the center of mass of the plunger group, which can be approximately considered to be on the plunger axis, and point M is the intersection of the separation line of the two contact stress segments and the plunger axis.

[0053] (1) Plunger chamber oil pressure Fp

[0054] When 0≤φ≤π,

[0055]

[0056] When π<φ≤2π,

[0057]

[0058] Where d is the plunger diameter, p is s is the outlet pressure of the plunger pump, and p0 is the inlet pressure of the plunger pump.

[0059] (2) Axial inertia force F of plunger assembly a

[0060]

[0061] Where m is the total mass of the plunger and the sliding shoe.

[0062] (3) Plunger assembly centrifugal force F c

[0063] Plunger group centrifugal force F c The point of action is at the center of mass C, and the direction is always along the radial direction of the plunger distribution circle and points outward.

[0064] F c =mRω 2 (7)

[0065] F c Decomposing along the x and y directions, we get:

[0066]

[0067] (4) Cylinder cavity oil pressure F u

[0068] The part of the plunger extending out of the cylinder cavity is a curved surface, and the oil pressure in the cylinder cavity is:

[0069]

[0070] F u Decomposing along the y direction and the z direction, we get:

[0071] F uz =-F u cosβ

[0072] F uy =-F u sinβ (10)

[0073] Where, d 2 is the outer diameter of the sliding shoe sealing band, p e is the oil pressure in the cylinder cavity.

[0074] (5) The reaction force F of the swash plate on the piston assembly N

[0075] The reaction force F of the swash plate on the plunger group N The direction is always perpendicular to the swash plate surface and can be decomposed into F along the y direction and the z direction. Ny and F Nz .

[0076] F Ny =F N sinβ

[0077] F Nz =F N cosβ (11)

[0078] The oil pressure between the oil suction stroke shoe and the swash plate is approximately pe ,but:

[0079]

[0080] (6) Lateral forces F1 and F2 between the plunger and the plunger hole wall

[0081] The component of the swash plate reaction force F ny , Plunger group centrifugal force F c , Friction force F between the sliding shoe and the swash plate b and plunger group gravity F g Under the action of , the plunger hole undergoes elastic deformation, and two contact stresses are generated at the front and rear ends of the plunger cylinder length. These two stresses can be approximately regarded as continuous linearly distributed stresses, and their resultant forces are assumed to be F1 and F2 respectively. During the movement, the magnitude and direction of F1 and F2 are always in dynamic change. F1 is decomposed into F along the x direction and the y direction. 1x and F 1y , F2 is decomposed into F along the x and y directions 2x and F 2y ,like Figure 6 shown.

[0082] The clearance between the plunger and the plunger hole is much smaller than the plunger diameter and the length of the plunger in the cylinder, so it can be assumed to be clearance-free sliding. At the same time, it is assumed that the sliding friction will not affect the distribution of the contact pressure of the plunger pair, and there is no relative rotation between the sliding shoe and the plunger ball head. Then, according to the stress triangle similarity principle, the contact length between the plunger and the plunger hole wall is:

[0083]

[0084] l=l1+l2 (15)

[0085] After finishing, we can get:

[0086]

[0087] (7) Friction force F between the plunger and the plunger hole wall f

[0088] There are two types of friction between the plunger and the plunger hole wall. One is the Coulomb friction caused by the lateral forces F1 and F2, and the other is the viscous friction caused by the viscosity of the oil. Because the Coulomb friction of the plunger pair is much larger than the viscous friction, it is assumed that the friction between the plunger and the plunger hole wall is mainly manifested as Coulomb friction, then:

[0089] When 0≤φ≤π,

[0090] F f =-f1(F1+F2) (18)

[0091] When π<φ≤2π,

[0092] F f =f1(F1+F2) (19)

[0093] Where f1 is the Coulomb friction coefficient of the plunger pair.

[0094] According to the above analysis, if Figure 7 , using MATLAB to obtain the curves of the lateral forces F1 and F2 between the plunger and the plunger hole wall as the cylinder body rotates. Figure 7 It can be seen that when the plunger moves in the oil discharge stroke, as the cylinder body rotation angle increases, the lateral forces F1 and F2 between the plunger and the plunger hole wall gradually increase, and the lateral force reaches the maximum at 5°, at which time F1 is 2350N and F2 is 1190N, and then the lateral force gradually decreases, and is the smallest at the bottom dead center position, and F1 is always greater than F2. This is because among the several forces that cause the lateral force of the plunger, the y-direction component force F of the swash plate reaction force is Ny and the centrifugal force F of the plunger group c Plays a major role, at the top dead center position F Ny With F c In the same plane and in the same direction, due to the existence of the coulomb friction of the sliding shoe pair, the lateral force of the plunger is not the maximum at this time, but reaches the maximum when it rotates a smaller angle of 5°. After that, as the rotation angle of the cylinder increases, F Ny With F c The angle gradually increases, and the resultant force gradually decreases, so the lateral force of the plunger gradually decreases. After passing the bottom dead center, due to the sudden change in the oil pressure in the plunger chamber, the lateral force of the plunger also suddenly changes, and F1 suddenly changes upward and F2 suddenly changes downward. When the plunger moves in the oil suction stroke, as the rotation angle of the cylinder body increases, the lateral forces F1 and F2 between the plunger and the plunger hole wall gradually increase, and F1 is always greater than F2. It can be seen that due to the difference in the sizes of F1 and F2, the plunger and the cylinder body have a tendency to wear eccentrically. Therefore, the device provided in this embodiment can provide a magnetic field force to compensate for the difference between F1 and F2 through the flow of magnetorheological fluid. Specifically, when F1 is greater than F2, the plunger has a tendency to wear eccentrically downward, the distance between the lower part of the plunger and the permanent magnetic plunger barrel becomes smaller, the magnetorheological fluid is subjected to an increase in magnetic field repulsion to compensate for F2, and the plunger deflects to the middle position. Similarly, when F2 is greater than F1, the magnetic field force compensates for F1, and under the joint action of the two, the plunger-cylinder body gap is adaptively adjusted.

[0095] In this embodiment, by arranging the permanent magnetic plunger barrel 4 in the plunger hole 5, the plunger 1 is in contact with the permanent magnetic plunger barrel 4, and the plunger 1 does not directly contact the cylinder body 2 by friction, thereby preventing the cylinder body 2 from being worn and protecting the cylinder body 2. When the permanent magnetic plunger barrel 4 is worn, only the permanent magnetic plunger barrel 4 needs to be replaced or repaired, thereby reducing the cost of repair and replacement.

[0096] In some embodiments, the permanent magnetic plunger cylinder 4 is made of permanent magnetic material with strong magnetism and constant magnetism, thereby improving the stability of the external magnetic field.

[0097] In this embodiment, by introducing magnetorheological fluid 3 and permanent magnetic plunger tube 4 into the plunger cylinder assembly, a new vibration reduction and clearance adaptive adjustment scheme is provided, which has a significant vibration reduction effect and is suitable for various axial piston 1 pump applications, and has broad application prospects and market value.

[0098] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. An axial piston pump with vibration reduction and clearance adaptive adjustment functions, characterized in that: It includes a plunger-cylinder assembly, which is composed of a plunger, a cylinder, a magnetorheological fluid, a permanent magnetic plunger barrel and a plunger hole; A cavity is provided between the inner and outer walls of the plunger, and the magnetorheological fluid fills the cavity and can flow freely in the cavity; under the action of an external magnetic force, the magnetorheological fluid has a chain structure; The plunger hole is arranged in a circumferential manner inside the cylinder body, and the plunger hole is used to accommodate the permanent magnetic plunger cylinder and the plunger; The permanent magnetic plunger barrel is detachably fixed on the cylinder body; the plunger is embedded in the permanent magnetic plunger barrel, and the permanent magnetic plunger barrel and the plunger are clearance-fitted.

2. The axial piston pump with vibration reduction and clearance adaptive adjustment function according to claim 1, characterized in that: The cavity is arranged around the axis of the plunger in a surrounding manner; the cavity is a closed cavity.

3. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 2, characterized in that: A small hole is provided on the outer wall of the plunger, and the small hole has sealing performance; The magnetorheological fluid enters the cavity through the small hole.

4. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 1, characterized in that: The permanent magnetic plunger cylinder is detachably fixed to the plunger hole via a clamping groove.

5. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 1, characterized in that: The permanent magnetic plunger barrel is made of a material with strong wear resistance; the plunger is in contact with the permanent magnetic plunger barrel.

6. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 5, characterized in that: The permanent magnetic plunger cylinder is made of permanent magnetic material.

7. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 1, characterized in that: An oil film is arranged on the inner wall of the permanent magnetic plunger cylinder, and the oil film is in contact with the plunger.

8. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 1, characterized in that: The magnetorheological fluid consists of magnetic particles and carrier liquid.

9. The axial piston pump with vibration reduction and clearance adaptive adjustment functions according to claim 8, characterized in that: The magnetic particles are made of ferromagnetic materials, including iron, cobalt and nickel; the carrier liquid is low-viscosity mineral oil or silicone oil.

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