Dynamic balance characteristic calculation method for floating type valve plate of axial plunger pump

Abstract

The invention belongs to the technical field of hydraulic pressure, and particularly relates to an axial plunger pump floating type valve plate dynamic balance characteristic calculation method which utilizes a plunger pump dynamic model to obtain pressure change curves in high-pressure and low-pressure kidney-shaped grooves, plunger cavities and auxiliary piston cavities of a plunger pump. On the basis, the flow distribution pair is divided into a high-pressure and low-pressure kidney-shaped groove area, a cavity control area and a partition area, and it is assumed that the pressure of the partition area is linearly distributed in the radial direction, so that a circumferential distribution function of the oil film pressure of the flow distribution pair is obtained. And then, further taking the conclusion that the flow distribution pair oil film follows the logarithmic attenuation law in the radial direction to obtain a new calculation method of the separation force of the flow distribution pair oil film, and realizing calculation of the dynamic balance characteristic of the valve plate. Compared with the prior art, the method has higher calculation precision and has better universality for valve plates of different structures. Compared with a modern oil film lubrication theory numerical calculation method, the method has higher calculation efficiency and calculation stability, and is more suitable for carrying out iterative optimization of structural parameters during engineering design.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic technology, and in particular relates to a method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump. Background Art

[0002] As a hydraulic power element, the swash plate axial piston pump is widely used in large load and high power occasions due to its advantages of high output pressure, high efficiency, simple and compact structure and convenient flow regulation. In the swash plate axial piston pump, the distribution pair composed of the cylinder body and the distribution plate is one of its three key friction pairs. It not only plays an important role in distributing the inlet and outlet oil, but also realizes the sealing function of high temperature and high pressure oil and the function of sliding bearing under high speed and heavy load. Therefore, the distribution pair of the swash plate axial piston pump usually designs the cylinder body as a "floating type", so that the oil film gap of the distribution pair can be adaptively adjusted under the changing external load by relying on the micro-floating ability of the cylinder body. However, since the centrifugal overturning moment of the cylinder body increases sharply with the increase of the cylinder body speed, the cylinder body will produce the "cylinder overturning" phenomenon under high speed, which seriously affects the working performance of the high-speed axial piston pump.

[0003] The new design of floating valve plate and rigid connection between cylinder body and pump shaft fundamentally solves the problem of "cylinder body overturning" at high speed. Therefore, with the development trend of high speed of inclined plate axial piston pump, the design of floating valve plate has been paid more and more attention. The principle diagram of the valve pair of "floating valve plate" is as follows Figure 2 As shown in the figure, the floating valve plate is subjected to two hydraulic forces, one is the separation force generated by the oil film in the valve pair gap, and the other is the compression force generated by the back oil chamber. The balance between the compression force and the separation force determines the floating characteristics of the valve plate, which is crucial in the design of the floating valve plate.

[0004] The structure of the traditional floating distribution plate is shown in Figure 3(a). To calculate the separation force of the distribution plate, the classic method is to split the distribution pair oil film into high-pressure and low-pressure areas along the circumferential direction, and then use the law of radial logarithmic attenuation of the oil film pressure in the parallel plate annular gap to calculate the separation force of the distribution pair oil film. However, for the new structure of the floating distribution plate with a larger high (low) pressure waist groove starting angle as shown in Figure 3(b), continuing to use the above classic distribution plate separation force calculation method will produce significant calculation deviations. This is because, for the traditional floating distribution plate shown in Figure 3(a), its dead angle is only slightly larger than the waist groove angle at the tail end of the plunger cavity, and the distribution pair oil film completes the transition between the high and low pressure zones within a very narrow angular range in the circumferential direction; in addition, the high and low switching process of the plunger cavity is extremely short, so the distribution pair oil film can be simply split into high-pressure and low-pressure areas for consideration, and the auxiliary piston cavity (reference Figure 6) The pressure is simplified to only have two levels, high and low pressure. However, for the floating valve plate shown in Figure 3(b), the enlarged dead zone of the valve plate significantly widens the high-low pressure transition area of ​​the valve plate oil film and significantly lengthens the high-low pressure switching transition process of the plunger cavity, thus breaking the applicable conditions of the classic separation force calculation method.

[0005] It should be said that the currently widely used numerical calculation method of lubricating oil film theory based on the Reynolds equation can accurately obtain the complete pressure distribution law of the oil film of the distribution pair, including that shown in Figure 3 (a) and Figure 3 (b), and realize the calculation of the separation force of the oil film of the distribution pair under general circumstances. However, when this method is applied to actual engineering design, it is limited by the shortcomings of low calculation efficiency and poor numerical stability, and it is difficult to realize the automatic iterative optimization design of structural parameters. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The technical problem to be solved by the present invention is: in view of the problem that the classic method for calculating the separation force of a distribution plate is not suitable for a floating distribution plate with a new structure, how to propose a more universal, sufficiently accurate and at the same time sufficiently efficient method for calculating the separation force of a floating distribution plate to provide support for the dynamic balance design of the floating distribution plate.

[0008] (II) Technical solution

[0009] In order to solve the above technical problems, the present invention provides a method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump, the method comprising the following steps:

[0010] Step 1: Let the pressure p at the mid-diameter of the oil film be v With the valve plate position angle The distribution function of

[0011]

[0012] The separation force F0 of the oil film on the distribution plate is

[0013]

[0014] Among them, r1 is the inner diameter of the distribution plate sealing belt, r2 is the inner diameter of the distribution plate waist groove, r3 is the outer diameter of the distribution plate waist groove, and r4 is the outer diameter of the distribution plate sealing belt. is the polar angle of a point on the distribution plate;

[0015] Step 2. Define the "cavity control area" and "partition area" in the distribution auxiliary oil film: the cavity control area refers to the area covered by the waist-shaped groove at the tail end of the plunger cavity, and the partition area refers to the transition area between the high- and low-pressure waist-shaped grooves and the waist-shaped groove at the tail end of the plunger cavity; using the existing floating distribution plate axial piston pump dynamics model, the dynamic change curves of the oil pressure of the high- and low-pressure waist-shaped grooves, each plunger cavity, and the upper and lower auxiliary piston cavities are obtained, and it is further assumed that the pressure of the oil film in the partition area obeys a linear transition along the circumferential direction; in summary, the distribution function is calculated Substitute into formula (2) to calculate the separation force F0;

[0016] Step 3: The clamping force on the floating valve plate is the hydraulic pressure provided by the four main hydraulic chambers and two auxiliary piston chambers on its back; the two auxiliary piston chambers are divided into an upper auxiliary piston chamber and a lower auxiliary piston chamber; the four main hydraulic chambers are connected to the pump outlet oil circuit and the pump inlet oil circuit respectively, so their pressures are respectively the pump outlet high pressure p H and pump inlet low pressure p L ; The two auxiliary piston chambers are alternately connected and disconnected with each plunger chamber, and their pressures are expressed as p f1 and p f2 ;

[0017] In summary, the calculation formula for the compression force on the distribution plate is further obtained as follows:

[0018]

[0019] Where D1 and D2 are the diameters of the main hydraulic chamber and auxiliary piston chamber of the floating valve plate respectively; f1 - Upper auxiliary piston chamber pressure, p f2 - Pressure in the lower auxiliary piston chamber;

[0020] Step 4: Calculate the compression coefficient ε of the distribution plate

[0021]

[0022] Among them, in step 2, the dynamic model of the floating distribution plate axial piston pump is any model that can simulate the dynamic change curves of the high and low pressure waist grooves, each plunger cavity, and the upper and lower auxiliary piston cavities of the distribution plate in the floating distribution plate plunger pump.

[0023] (III) Beneficial effects

[0024] Compared with the prior art, the present invention uses the existing axial piston pump dynamics model to obtain the circumferential distribution function of the oil film pressure of the distribution pair, and based on this, proposes a new method for calculating the separation force on the floating distribution plate. Compared with the classical calculation method, this method is more universal and is applicable to the distribution plate structure shown in Figure 3 (a) and Figure 3 (b). Compared with the modern oil film theory calculation method based on the Reynolds equation, it is more efficient, more applicable in engineering, and more suitable for iterative optimization of structural parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the balance calculation method for the floating valve plate of an axial piston pump;

[0026] Figure 2 This is the principle diagram of the flow distribution pair of the "floating distribution plate";

[0027] FIG3(a) and FIG3(b) are schematic diagrams of the conventional structure and the new structure of the floating valve plate, respectively;

[0028] Figure 4 It is a schematic diagram of radial distribution law of oil film pressure in the distribution pair;

[0029] In the figure, r1 is the inner diameter of the distribution plate sealing belt, r2 is the inner diameter of the distribution plate waist groove, r3 is the outer diameter of the distribution plate waist groove, r4 is the outer diameter of the distribution plate sealing belt, - the polar angle of a point on the valve plate;

[0030] Figure 5 It is a schematic diagram of the valve plate cavity control area and the partition area;

[0031] In the figure, - cylinder angle;

[0032] Figure 6 It is a floating type valve plate pressing surface structure;

[0033] In the figure, - Cylinder angle, p H - Pump outlet high pressure, p L - Pump inlet low pressure, p f1 - Pressure in the upper and lower auxiliary piston chambers, p f2 -lower auxiliary piston chamber pressure, x-horizontal coordinate axis, y-vertical coordinate axis, D1-main hydraulic chamber diameter, D2-auxiliary piston chamber diameter, L x -x-direction positioning dimension of the main hydraulic chamber, L y - Y-direction positioning dimension of the main hydraulic chamber, L f -The distance between the auxiliary piston cavity and the origin (center of the valve plate);

[0034] Figure 7 The figure is a comparison chart of the calculation results of the method proposed in the present invention and the traditional method.

[0035] Figure 8 In order to utilize the method proposed in the present invention, the calculation results of the balance characteristics of the original structure of the distribution plate in Figure 3 (a) and the new structure of the distribution plate in Figure 3 (b) are shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0037] In order to solve the above technical problems, the present invention provides a method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump, the method comprising the following steps:

[0038] Step 1: Let the pressure p at the mid-diameter of the oil film be v With the valve plate position angle The distribution function of

[0039]

[0040] Continuing to use the conclusion of the classic analytical method that the oil film of the distribution pair obeys the logarithmic decay law in the radial direction, the separation force F0 of the oil film on the distribution plate is

[0041]

[0042] Among them, r1 is the inner diameter of the distribution plate sealing belt, r2 is the inner diameter of the distribution plate waist groove, r3 is the outer diameter of the distribution plate waist groove, and r4 is the outer diameter of the distribution plate sealing belt. is the polar angle of a point on the distribution plate;

[0043] Step 2: Figure 5 As shown in the figure, in the oil film of the distribution sub-distributor, the "cavity control area" and "partition area" are defined: the cavity control area refers to the area covered by the waist-shaped groove at the tail end of the plunger cavity, and the partition area refers to the transition area between the high-low pressure waist-shaped groove and the waist-shaped groove at the tail end of the plunger cavity; using the existing floating distribution plate axial piston pump dynamics model, the dynamic change curves of the oil pressure of the high-low pressure waist-shaped groove, each plunger cavity, and the upper and lower auxiliary piston cavities are obtained, and it is further assumed that the pressure of the oil film in the partition area obeys a linear transition along the circumferential direction; in summary, the distribution function is calculated Substitute into formula (2) to calculate the separation force F0;

[0044] Step 3: Figure 6 As shown in the figure, the clamping force on the floating valve plate is the hydraulic pressure provided by the four main hydraulic chambers and two auxiliary piston chambers on its back; the two auxiliary piston chambers are divided into an upper auxiliary piston chamber and a lower auxiliary piston chamber; the four main hydraulic chambers are connected to the pump outlet oil circuit and the pump inlet oil circuit respectively, so their pressures are respectively the pump outlet high pressure p H and pump inlet low pressure p L; The two auxiliary piston chambers are alternately connected and disconnected with each plunger chamber, and their pressures are expressed as p f1 and p f2 ;

[0045] In summary, the calculation formula for the compression force on the distribution plate is further obtained as follows:

[0046]

[0047] Where D1 and D2 are the diameters of the main hydraulic chamber and auxiliary piston chamber of the floating valve plate respectively; f1 - Upper auxiliary piston chamber pressure, p f2 - Pressure in the lower auxiliary piston chamber;

[0048] Step 4: Calculate the compression coefficient ε of the distribution plate

[0049]

[0050] Among them, in step 2, the dynamic model of the floating distribution plate axial piston pump is any model that can simulate the dynamic change curves of the high and low pressure waist grooves, each plunger cavity, and the upper and lower auxiliary piston cavities of the distribution plate in the floating distribution plate plunger pump.

[0051] Example 1

[0052] In this embodiment, for a plunger pump with 9 plungers and a displacement of 125 ml / r, under the conditions of a pump speed of 2000 r / min and a pump outlet pressure of 40 MPa, for a complete movement cycle, that is, the time when the cylinder body rotates from 0° to 40°, the new method proposed by the present invention and the traditional method are used to calculate the balance characteristics of the valve plate respectively; wherein the steps of the method of the present invention are as follows:

[0053] Step 1: Let the pressure p at the mid-diameter of the oil film be v With the valve plate position angle The distribution function of

[0054]

[0055] like Figure 4 As shown in the figure, we continue to use the conclusion of the classic analytical method that the oil film of the distribution pair obeys the logarithmic decay law in the radial direction, so the separation force F0 of the oil film on the distribution plate is

[0056]

[0057] Step 2: Calculate the distribution function of the oil film pressure along the circumferential direction of the distribution pair And the separation force F0 on the distribution plate. Figure 5As shown, in the oil film of the distribution sub-distributor, the "cavity control area" and "partition area" are defined: the cavity control area refers to the area covered by the waist-shaped groove at the tail end of the plunger cavity, and the partition area refers to the transition area between the high- and low-pressure waist-shaped grooves and the waist-shaped groove at the tail end of the plunger cavity. Using the existing dynamic model of the floating distribution plate axial piston pump, the dynamic change curves of the oil pressure of the high- and low-pressure waist-shaped grooves, the plunger cavity, and the upper and lower auxiliary piston cavities can be obtained, and it is further assumed that the pressure of the oil film in the partition area follows a linear transition along the circumferential direction. In summary, the distribution function can be calculated Substituting into formula (2), the separation force F0 can be calculated;

[0058] Step 3: Figure 6 As shown in the figure, the pressing force on the floating valve plate is the hydraulic pressure provided by the four main hydraulic chambers and two auxiliary piston chambers on its back; the four main hydraulic chambers are connected to the pump outlet oil circuit and the pump inlet oil circuit respectively, so their pressures are respectively the pump outlet high pressure p H and pump inlet low pressure p L The two auxiliary piston chambers are alternately connected and disconnected with each plunger chamber, and their pressures are expressed as p f1 and p f2 Using the existing dynamic model of floating valve plate axial piston pump, the pump outlet high pressure p can be obtained. H , Pump inlet low pressure p L and the pressures pf1 and pf2 of the two auxiliary piston chambers f2 .

[0059] In summary, the calculation formula for the pressure on the distribution plate can be further obtained as follows:

[0060]

[0061] Among them, D1 and D2 are the diameters of the main hydraulic chamber and auxiliary piston chamber of the floating valve plate respectively.

[0062] Step 4: Calculate the compression coefficient of the distribution plate

[0063]

[0064] For the traditional structure of the distribution plate shown in Figure 3 (a), the separation force, compression force and compression coefficient of the distribution plate are calculated using the traditional classical method and the new method proposed in this patent. The calculation results are as follows: Figure 7As shown. It can be seen that the calculation results obtained by the two calculation methods are very consistent, indicating that the proposed new method for calculating the balance of the distribution plate based on the dynamic model of the plunger pump is correct. In addition, the clamping force, separation force, and compression coefficient curves obtained by the traditional calculation method will undergo sudden changes at certain specific cylinder angle positions, while the clamping force, separation force, and compression coefficient curves calculated by the new method have a smooth transition throughout the entire cycle. This is because the new method takes into account the dynamic transition process of the high and low pressure switching of the plunger cavity and the auxiliary piston cavity, as well as the high and low pressure transition area of ​​the distribution auxiliary oil film.

[0065] Using the new method proposed in the present invention, the separation force, compression force and compression coefficient are calculated for the original structure and the new structure of the distribution plate shown in Figure 3 (a) and Figure 3 (b), respectively. The calculation results are as follows: Figure 8 shown.

[0066] In summary, the present invention belongs to the field of hydraulic technology, and specifically relates to a method for calculating the dynamic balance characteristics of a floating distribution plate of an axial piston pump, which uses a piston pump dynamics model to obtain the pressure change curves in the high and low pressure waist grooves, each piston cavity, and auxiliary piston cavity of the piston pump. On this basis, the distribution pair is divided into a high and low pressure waist groove area, a cavity control area, and a partition area, and it is assumed that the pressure in the partition area is linearly distributed along the radial direction, thereby obtaining the circumferential distribution function of the oil film pressure of the distribution pair. Then, further following the conclusion that the oil film of the distribution pair obeys the logarithmic attenuation law along the radial direction, a new method for calculating the separation force of the oil film of the distribution pair is obtained, and the calculation of the dynamic balance characteristics of the distribution plate is realized. Compared with the traditional classical analytical calculation method, this method has higher calculation accuracy and better universality for distribution plates of different structures. Compared with the modern oil film lubrication theory numerical calculation method, this method has higher calculation efficiency, better calculation stability, and is more suitable for iterative optimization of structural parameters during engineering design.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump, characterized in that: The method comprises the following steps: Step 1: Let the pressure p at the mid-diameter of the oil film be v With the valve plate position angle The distribution function of The separation force F0 of the oil film on the distribution plate is Among them, r1 is the inner diameter of the distribution plate sealing belt, r2 is the inner diameter of the distribution plate waist groove, r3 is the outer diameter of the distribution plate waist groove, and r4 is the outer diameter of the distribution plate sealing belt. is the polar angle of a point on the distribution plate; Step 2. In the oil film of the distribution sub-distributor, define the "cavity control area" and "partition area": ​​the cavity control area refers to the area covered by the waist-shaped groove at the tail end of the plunger cavity, and the partition area refers to the transition area between the high- and low-pressure waist-shaped grooves and the waist-shaped groove at the tail end of the plunger cavity; using the existing floating distribution plate axial piston pump dynamics model, the dynamic change curves of the oil pressure of the high- and low-pressure waist-shaped grooves, each plunger cavity, and the upper and lower auxiliary piston cavities are obtained, and it is further assumed that the pressure of the oil film in the partition area obeys a linear transition along the circumferential direction; in summary, the distribution function is calculated Substitute into formula (2) to calculate the separation force F0; Step 3: The clamping force on the floating valve plate is the hydraulic pressure provided by the four main hydraulic chambers and two auxiliary piston chambers on its back; the two auxiliary piston chambers are divided into an upper auxiliary piston chamber and a lower auxiliary piston chamber; the four main hydraulic chambers are connected to the pump outlet oil circuit and the pump inlet oil circuit respectively, so their pressures are respectively the pump outlet high pressure p H and pump inlet low pressure p L ; The two auxiliary piston chambers are alternately connected and disconnected with each plunger chamber, and their pressures are expressed as p f1 and p f2 ; In summary, the calculation formula for the compression force on the distribution plate is further obtained as follows: Where D1 and D2 are the diameters of the main hydraulic chamber and auxiliary piston chamber of the floating valve plate respectively; f1 - Upper auxiliary piston chamber pressure, p f2 -Lower auxiliary piston chamber pressure; Step 4: Calculate the compression coefficient ε of the distribution plate 2. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: In step 2, the dynamic model of the floating valve plate axial piston pump is any model that can simulate the dynamic change curves of the high and low pressure waist grooves, each plunger cavity, and the upper and lower auxiliary piston cavities of the valve plate in the floating valve plate plunger pump.

3. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: r1 is the inner diameter of the distribution plate sealing zone.

4. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: r2 is the inner diameter of the waist groove of the distribution plate.

5. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: r3 is the outer diameter of the waist groove of the distribution plate.

6. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: r4 is the outer diameter of the distribution plate sealing zone.

7. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: is the polar angle of a point on the distribution plate.

8. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: D1 and D2 are the diameters of the main hydraulic chamber and auxiliary piston chamber of the floating valve plate respectively.

9. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: p f1 is the pressure in the upper auxiliary piston chamber.

10. The method for calculating the dynamic balance characteristics of a floating valve plate of an axial piston pump according to claim 1, characterized in that: p f2 is the pressure in the lower auxiliary piston chamber.

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