Axial plunger pump

Abstract

The invention relates to the technical field of hydraulic pressure, in particular to an axial plunger pump. According to the axial plunger pump, an oil discharge port and an oil suction port are formed in a plate body of a valve plate unit. And the oil discharge port and the oil suction port are arc-shaped and are concentrically arranged. And the inner diameter of the oil discharge port is equal to that of the oil suction port. And the outer diameter of the oil discharge port is equal to that of the oil suction port. The supporting layer is fixedly connected with the tray body. An oil discharge groove and an oil suction groove are formed in the supporting layer of the valve plate unit. The oil discharge groove is communicated with the oil discharge port. And the oil discharge groove is arc-shaped and is concentric with the oil discharge port. The inner diameter of the oil discharging groove is smaller than that of the oil discharging opening. And the outer diameter of the oil discharge groove is equal to that of the oil discharge port. The oil suction groove is communicated with the oil suction port. And the oil suction groove is arc-shaped and is concentric with the oil suction port. The outer diameter of the oil suction groove is larger than that of the oil suction opening. The inner diameter of the oil suction groove is equal to that of the oil suction opening. Therefore, the problem of how to improve the anti-overturning capability of the plunger pump cylinder body under the extreme working condition is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulics, and in particular, to an axial piston pump. Background Art

[0002] In a distributed hydraulic system, an axial piston pump is a positive displacement hydraulic pump widely used in an aircraft hydraulic system. It uses the volume change of series-parallel cavities to establish pressure and transmit flow, realizing the conversion from the mechanical energy of the aircraft casing to hydraulic energy. The entire rotating assembly is immersed in the hydraulic oil of the housing. The main shaft drives the cylinder block to rotate through spline fitting, drives the slipper to slide on the swash plate, and forces the piston to reciprocate periodically in the cylinder block, thereby realizing the continuous oil suction and discharge of the piston pump.

[0003] The axial hydraulic piston pump is the core power element of an electro-hydrostatic actuator, featuring a compact structure, small size, and high power density. Given the extreme demand for weight reduction in aircraft, further increasing the rotational speed is the main research direction for achieving a high power density ratio and miniaturization of the electro-hydrostatic actuator. However, the cylinder block overturning caused by high speed poses a great challenge to the structural design of the axial piston pump. The abnormal wear caused by the slipper overturning under high-speed conditions is an important reason for the slipper failure, and the overturning moment under high-speed conditions is relatively large, easily leading to the overturning deformation of the drive shaft. At present, most of the research mainly focuses on low-speed conditions, lacking the analysis of the influence of ultra-high-speed conditions on the friction pair damage and the overturning of the rotating assembly of the axial piston pump. Moreover, the design results under low-speed conditions are not fully applicable to the design of high-speed axial piston pumps. Therefore, it is necessary to make corresponding improvements and optimizations to the structure of the traditional low-speed axial piston pump to meet the usage requirements under extreme conditions. Summary of the Invention

[0004] To solve the problem of how to improve the anti-overturning ability of the cylinder block of the piston pump under extreme conditions, the present invention provides an axial piston pump, which includes:

[0005] A housing unit;

[0006] A flow distribution plate unit, the flow distribution plate unit is located within the housing unit; the flow distribution plate unit includes a plate body and a support layer, the plate body has an oil discharge port and an oil suction port; both the oil discharge port and the oil suction port are arc-shaped and concentrically arranged; the inner diameter of the oil discharge port is equal to the inner diameter of the oil suction port; the outer diameter of the oil discharge port is equal to the outer diameter of the oil suction port; the support layer is fixedly connected to the plate body; the support layer has an oil discharge groove and an oil suction groove; the oil discharge groove is communicated with the oil discharge port; the oil discharge groove is arc-shaped and concentrically arranged with the oil discharge port; the central angle of the oil discharge port coincides with the central angle of the oil discharge groove; the inner diameter of the oil discharge groove is smaller than the inner diameter of the oil discharge port; the outer diameter of the oil discharge groove is equal to the outer diameter of the oil discharge port; the oil suction groove is communicated with the oil suction port; the oil suction groove is arc-shaped and concentrically arranged with the oil suction port; the central angle of the oil suction port coincides with the central angle of the oil suction groove; the outer diameter of the oil suction groove is larger than the outer diameter of the oil suction port; the inner diameter of the oil suction groove is equal to the inner diameter of the oil suction port;

[0007] A cylinder block unit, the cylinder block unit is located within the housing unit; one end of the cylinder block unit is attached to the support layer; the cylinder block unit is rotatably connected to the housing unit; the cylinder block unit includes a cylinder block body, and the cylinder block body has a plurality of plunger cavities;

[0008] A plunger unit, there are a plurality of plunger units, the plunger unit includes a plunger rod and a plunger ball head; the plunger rod is slidably connected to the cylinder block unit; the plunger rods are arranged in one-to-one correspondence with the plunger cavities; the plunger rod is slidably arranged within the plunger cavity; the plunger ball head is integrally formed with the plunger rod;

[0009] A slipper unit, the slipper unit is detachably connected to the plunger ball head;

[0010] An inclined plate unit, the inclined plate unit is located within the housing unit; the inclined plate unit is detachably connected to the housing unit; the slipper unit abuts against the inclined plate unit;

[0011] A drive shaft unit, the drive shaft unit drives the cylinder block unit to rotate;

[0012] A central spring unit, the central spring unit drives the slipper unit to tightly abut against the inclined plate unit.

[0013] In some embodiments, the cylinder block unit and the flow distribution plate unit form a flow distribution pair; the flow distribution pair is a high-pressure area at the position of the oil discharge groove; the flow distribution pair is a low-pressure area at the position of the oil suction groove;

[0014] The inner radius of the oil drain groove is the first radius r1'; the inner radius of the oil drain port is the second radius r2'; the outer radius of the oil suction port is the third radius r3'; the outer radius of the oil suction groove is the fourth radius r4'; the difference between the first radius and the second radius is the first offset value δ1; the difference between the third radius and the fourth radius is the second offset value δ2; the first offset value and the second offset value are related to the following formula:

[0015] M sx +M tx +M vx +M sh =0;

[0016]

[0017] where M sx is the non-inertial force overturning moment generated by the acting force of the swash plate unit on the plunger rod on the cylinder block unit in the reference direction; the reference direction is the direction from the center of the oil drain groove to the middle of the oil drain groove; M tx is the inertial force overturning moment generated by the inertial force of the movement of the plunger rod on the cylinder block unit; M vx is the total overturning moment generated by the oil film of the flow distribution pair on the cylinder block unit, and is equal to the sum of the overturning moments generated by the oil films in the high-pressure area and the low-pressure area of the flow distribution pair on the cylinder block unit; M sh is the torque generated by the drive shaft unit on the cylinder block unit in the reference direction; r p is the radius of the cylinder block unit; L c is the distance from the intersection of the swash plate unit and the drive shaft unit to the flow distribution plate unit; β is the inclination angle of the swash plate unit; is the pressure of the i-th plunger chamber; the circle formed by the distribution of multiple plunger units is the distribution circle; R is the radius of the distribution circle; is the angular displacement of the i-th plunger rod; F sp is the pre-tightening force of the central spring unit.

[0018] In some embodiments, the inertial force overturning moment generated by the inertial force of the movement of the plunger rod on the cylinder block unit is calculated according to the following formula:

[0019]

[0020] where N is the number of plunger units; ω is the angular velocity.

[0021] In some embodiments, the first offset value is also related to the following formula:

[0022]

[0023] Among them, M vHx is the tipping moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit when the first offset value is zero; θ1 is the starting angle of the high-pressure area of the flow distribution pair; θ2 is the ending angle of the high-pressure area of the flow distribution pair; p H is the load pressure; r1 is the inner radius of the inner sealing band in the flow distribution pair; r2 is the outer radius of the inner sealing band in the flow distribution pair; r3 is the inner radius of the outer sealing band in the flow distribution pair; r4 is the outer radius of the outer sealing band in the flow distribution pair; r1 ′ = r1; r2 ′ = r2 - δ1; r3 ′ = r3 + δ2; r4 ′ = r4.

[0024] In some embodiments, the first offset value is calculated according to the following formula:

[0025]

[0026] Among them, M vHx′ is the tipping moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit when the first offset value is greater than zero; δ1 is the first offset value.

[0027] In some embodiments, the second offset value is also related to the following formula:

[0028]

[0029] Among them, M vLx′ is the tipping moment generated by the oil film in the low-pressure area of the flow distribution pair on the cylinder block unit; θ3 is the starting angle of the low-pressure area of the flow distribution pair; θ4 is the ending angle of the low-pressure area of the flow distribution pair; p L is the tipping force generated by the oil film formed between the oil suction groove and the cylinder block unit on the cylinder block unit.

[0030] In some embodiments, the axial piston pump further includes a valve unit, the valve unit includes a valve core body and a valve core spring; the valve unit is detachably connected to the flow distribution plate; the valve unit controls the on-off of the oil discharge port and the oil suction port with the plunger cavity respectively;

[0031] The calculation processes of the first offset value and the second offset value are also related to the following formula:

[0032]

[0033] Among them, L s is the axial length of the contact part between the cylinder block unit and the drive shaft; F v is the thrust of the valve core body; Fsp is the pre-compression force of the spool valve spring.

[0034] In some embodiments, the absolute value of the first offset value is less than the absolute value of the second offset value.

[0035] In some embodiments, the depth of the oil drain groove is less than the depth of the oil drain port; the depth of the oil suction groove is less than the depth of the oil suction port; the depth directions of the oil drain groove, the oil drain port, the oil suction groove, and the oil suction port are perpendicular to the disk body.

[0036] In some embodiments, the support layer and the disk body are integrally formed by three-dimensional printing.

[0037] To solve the problem of how to improve the anti-overturning ability of the cylinder block of the piston pump under extreme working conditions, the present invention has the following advantages:

[0038] By reasonably changing the offset dimensions of the oil drain groove and the oil suction groove on the support layer, the inner diameter of the oil drain groove is made smaller than the inner diameter of the oil drain port, and the outer diameter of the oil suction groove is made larger than the outer diameter of the oil suction port. Thus, the instantaneous acting torque of the support layer of the flow distribution disk unit on the cylinder block unit can be changed, and the balance design of the overturning torque of the cylinder block unit can be realized, thereby weakening the lateral offset of the cylinder block unit under the high-speed working condition of the axial piston pump and improving the reliability of the axial piston pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Shows a schematic diagram of an axial piston pump according to an embodiment;

[0040] Figure 2 Shows a three-dimensional schematic diagram of a flow distribution disk unit according to an embodiment;

[0041] Figure 3 Shows Figure 2 A plan schematic diagram of the flow distribution disk unit in the embodiment;

[0042] Figure 4 Shows Figure 2 A sectional schematic diagram of the flow distribution disk unit in the embodiment;

[0043] Figure 5 Shows a schematic diagram of the simulation of the axial piston pump before improvement according to an embodiment;

[0044] Figure 6 Shows a schematic diagram of the simulation of the axial piston pump after improvement according to an embodiment.

[0045] Reference numerals: 10 housing unit; 20 flow distribution plate unit; 21 plate body; 22 support layer; 23 oil suction port; 24 oil discharge port; 25 oil suction groove; 26 oil discharge groove; 30 cylinder block unit; 31 cylinder block body; 32 plunger chamber; 40 plunger unit; 41 plunger rod; 42 plunger ball head; 50 slipper unit; 60 swash plate unit; 70 drive shaft unit; 80 central spring unit. Detailed implementation manners

[0046] The present disclosure will now be described with reference to several exemplary embodiments. It should be understood that the description of these embodiments is only for enabling those of ordinary skill in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0047] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to". The term "based on" is to be construed as "at least partially based on". The terms "an embodiment" and "a kind of embodiment" are to be construed as "at least one embodiment". The term "another embodiment" is to be construed as "at least one other embodiment". The orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation. And, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present application can be understood according to specific circumstances. In addition, the terms "mounted", "arranged", "provided with", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral structure; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, or there may be internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated device, element or component. Unless otherwise specified, the meaning of "a plurality" is two or more.

[0048] In this embodiment, in the high-speed operating condition of the axial piston pump, the tilting of the cylinder block caused by its high-speed operation poses a great challenge to the structural design of the axial piston pump. The abnormal wear caused by the tilting of the slipper in the high-speed operating condition is an important reason for the slipper failure. Moreover, when the rotational speed of the axial piston pump exceeds 10,000 revolutions per minute, the inertial tilting moment of the cylinder block is equivalent to the reaction thrust moment of the oil film of the flow distribution pair. At this time, the cylinder block is extremely prone to tilting and deforming towards the dead center outside the flow distribution plate, which limits the high-speed application of the electro-hydrostatic actuator. To solve the above problems, this embodiment discloses an axial piston pump. As Figure 1 shown, the axial piston pump includes: a housing unit 10, a flow distribution plate unit 20, a cylinder block unit 30, a plunger unit 40, a slipper unit 50, a swash plate unit 60, a drive shaft unit 70, and a central spring unit 80.

[0049] The housing unit 10 serves as the housing of the axial piston pump, which is used to protect the internal components of the axial piston pump, prevent oil leakage and the entry of external foreign objects.

[0050] The flow distribution plate unit 20 is located inside the housing unit 10; as Figure 2 、 Figure 3 、 Figure 4 shown, the flow distribution plate unit 20 includes a plate body 21 and a support layer 22. The plate body 21 is provided with an oil discharge port 24 and an oil suction port 23; both the oil discharge port 24 and the oil suction port 23 are arc-shaped and concentrically arranged; the inner diameter of the oil discharge port 24 is equal to the inner diameter of the oil suction port 23; the outer diameter of the oil discharge port 24 is equal to the outer diameter of the oil suction port 23; the support layer 22 is fixedly connected to the plate body 21; the support layer 22 is provided with an oil discharge groove 26 and an oil suction groove 25; the oil discharge groove 26 is communicated with the oil discharge port 24; the oil discharge groove 26 is arc-shaped and concentric with the oil discharge port 24; the central angle of the oil discharge port 24 coincides with the central angle of the oil discharge groove 26; the inner diameter of the oil discharge groove 26 is smaller than the inner diameter of the oil discharge port 24; the outer diameter of the oil discharge groove 26 is equal to the outer diameter of the oil discharge port 24; the oil suction groove 25 is communicated with the oil suction port 23; the oil suction groove 25 is arc-shaped and concentric with the oil suction port 23; the central angle of the oil suction port 23 coincides with the central angle of the oil suction groove 25; the outer diameter of the oil suction groove 25 is larger than the outer diameter of the oil suction port 23; the inner diameter of the oil suction groove 25 is equal to the inner diameter of the oil suction port 23; through the above settings, the oil suction groove 25 and the oil discharge groove 26 are respectively offset from the oil suction port 23 and the oil discharge port 24, so that when an oil film is formed between the support layer 22 and the cylinder block unit 30, the oil film around the oil discharge groove 26 is closer to the center of the flow distribution plate unit 20, and the oil film around the oil suction groove 25 is farther from the center of the flow distribution plate unit 20, balancing the uniformity of the overall tilting moment of the oil film of the flow distribution pair at the support layer 22 on the cylinder block unit 30, thereby weakening the lateral offset of the cylinder block unit 30 under the high-speed operating condition of the axial piston pump and improving the reliability of the axial piston pump.

[0051] The cylinder block unit 30 is located inside the housing unit 10; one end of the cylinder block unit 30 is in contact with the support layer 22; the cylinder block unit 30 is rotatably connected to the housing unit 10; the cylinder block unit 30 includes a cylinder block body 31, and the cylinder block body 31 is provided with a plurality of plunger cavities 32; the hydraulic function of the axial piston pump is realized by the piston movement of the plunger unit 40 in the plunger cavities 32 of the cylinder block body 31.

[0052] There are a plurality of plunger units 40, and the plunger unit 40 includes a plunger rod 41 and a plunger ball head 42; the plunger rod 41 is slidably connected to the cylinder block unit 30; the plunger rods 41 are arranged in one-to-one correspondence with the plunger cavities 32; the plunger rod 41 is slidably arranged in the plunger cavity 32; the plunger ball head 42 is integrally formed with the plunger rod 41; the piston movement of the plunger unit 40 in the plunger cavity 32 is used to cooperate with the port plate unit 20 to realize the oil suction and oil discharge operations.

[0053] The slipper unit 50 is detachably connected to the plunger ball head 42; the swash plate unit 60 is located inside the housing unit 10; the swash plate unit 60 is detachably connected to the housing unit 10; the slipper unit 50 abuts against the swash plate unit 60; the drive shaft unit 70 drives the cylinder block unit 30 to rotate; the central spring unit 80 drives the slipper unit 50 to tightly abut against the swash plate unit 60.

[0054] In this embodiment, as Figure 5 、 Figure 6 shown, on the basis of establishing the cylinder block mathematical model under the combined action of loads such as the inertial overturning moment and the hydraulic overturning moment of the axial piston pump, the motion law characteristics of the axial piston pump are analyzed to reveal the cylinder block overturning bearing mechanism under the action of complex loads. Among them, Figure 5 can be obtained by substituting the original structural parameters in Table 1 below into the simulation software, Figure 6 can be obtained by substituting the structural optimization parameters in Table 1 below into the simulation software. Figure 5 shows that the axial piston pump is prone to overturning and its overturning motion direction under the original structural parameters; Figure 5 And Figure 6 shows the mechanism of the deformation amount of the axial piston pump decreasing from large to small according to the order of red, orange, yellow, green, cyan, and blue. Figure 6 The axial piston pump in

[0055]

[0056] like Figure 1 As shown, the cylinder unit 30 and the distribution plate unit 20 form a distribution pair; Figure 2 As shown, the position of the distribution pair at the oil discharge groove 26 is a high-pressure area; the position of the distribution pair at the oil suction groove 25 is a low-pressure area.

[0057] like Figure 3 As shown, the inner radius of the oil drain groove 26 is a first radius r1′; the inner radius of the oil drain port 24 is a second radius r2′; the outer radius of the oil suction port 23 is a third radius r3′; and the outer radius of the oil suction groove 25 is a fourth radius r4′. The difference between the first and second radii is a first offset value δ1; and the difference between the third and fourth radii is a second offset value δ2. The first and second offset values are related by the following formula:

[0058] M sx +M tx +M vx +M sh =0;

[0059]

[0060] Among them, M sx M is the non-inertial overturning moment generated by the force of the swash plate unit 60 on the plunger rod 41 on the cylinder unit 30 in the reference direction; the reference direction is the direction from the center of the oil drain groove 26 to the middle of the oil drain groove 26; tx M is the inertia overturning moment generated by the inertia force of the piston rod 41 on the cylinder unit 30; vx is the total overturning moment generated by the oil film of the distribution pair on the cylinder unit 30, and is equal to the sum of the overturning moments generated by the oil film in the high-pressure area and the low-pressure area of the distribution pair on the cylinder unit 30, that is: M vx =M vHx +M vLx ;M sh M is the torque generated by the drive shaft unit 70 on the cylinder unit 30 in the reference direction; sh The value of M can be obtained by the above moment balance equation (i.e. sx +M tx +M vx +M sh =0), it is found that by adjusting the first offset value and the second offset value, it is possible to reduce M sh The effect of the value of can improve the anti-overturning moment capacity of the plunger pump cylinder under extreme working conditions. p is the radius of the cylinder unit 30; L c is the distance from the intersection of the swash plate unit 60 and the drive shaft unit 70 to the valve plate unit 20; β is the inclination angle of the swash plate unit 60; is the pressure of the i-th plunger chamber 32; the circle formed by the distribution of multiple plunger units 40 is the distribution circle; R is the radius of the distribution circle; is the angular displacement of the i-th plunger rod 41; F sp is the pre-tightening force of the central spring unit 80. Through the above calculations, the non-inertial force overturning moment M generated by the acting force of the swash plate unit 60 on the plunger rod 41 in the reference direction on the cylinder block unit 30 sx is obtained, which facilitates the subsequent determination of the offset dimensions of the oil discharge groove 26 and the oil suction groove 25, that is, the first offset value and the second offset value.

[0061] In this embodiment, the inertial force overturning moment generated by the inertial force of the movement of the plunger rod 41 on the cylinder block unit 30 is calculated according to the following formula:

[0062]

[0063] where M tx is the inertial force overturning moment generated by the inertial force of the movement of the plunger rod 41 on the cylinder block unit 30; N is the number of plunger units 40; ω is the angular velocity. Through the above calculations, the inertial force overturning moment generated by the inertial force of the movement of the plunger rod 41 on the cylinder block unit 30 can be obtained, so as to further improve the analysis of the motion law characteristics of the axial piston pump and reveal the overturning bearing mechanism of the cylinder block unit 30 under complex loads.

[0064] In this embodiment, the first offset value is also related to the following formula:

[0065]

[0066] where M vHx is the overturning moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit 30 when the first offset value is zero; θ1 is the starting angle of the high-pressure area of the flow distribution pair; θ2 is the ending angle of the high-pressure area of the flow distribution pair; p H is the load pressure; r1 is the inner radius of the inner sealing belt of the flow distribution pair; r2 is the outer radius of the inner sealing belt of the flow distribution pair; r3 is the inner radius of the outer sealing belt of the flow distribution pair; r4 is the outer radius of the outer sealing belt of the flow distribution pair; r1 ′ = r1; r2 ′ = r2 - δ1; r3 ′ = r3 + δ2; r4 ′ = r4.

[0067] Since the cylinder block unit 30 is also subjected to the acting moment of the oil film of the flow distribution pair in addition to the acting moments of the plunger unit 40 and the swash plate unit 60, by calculating the overturning moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit 30 when the first offset value is zero through the above calculations, the reliability of the analysis and calculation of the overturning moment of the axial piston pump can be improved.

[0068] In this embodiment, the first offset value is calculated according to the following formula:

[0069]

[0070] where M vHx′ is the tipping moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit 30 when the first offset value is greater than zero; δ1 is the first offset value.

[0071] Through the above calculation, it is convenient to determine the first offset value. During the rotation of the cylinder block unit 30 relative to the flow distribution plate unit 20, the oil suction groove 25 and the oil discharge groove 26 on the support layer 22 will successively come into contact with, overlap with, and separate from the plunger cavity 32. During this process, the effective wrap angle range of the flow distribution pair and the size of the formed oil film sealing band will change accordingly. By reasonably changing the offset size of the support layer 22, the instantaneous acting moment of the oil film of the flow distribution pair on the cylinder block unit 30 can be changed, realizing the balanced design of the tipping moment of the cylinder block unit 30, thereby weakening the lateral offset of the cylinder block unit 30 at ultra-high speeds.

[0072] In this embodiment, the second offset value is also related to the following formula:

[0073]

[0074] where M vLx′ is the tipping moment generated by the oil film in the low-pressure area of the flow distribution pair on the cylinder block unit 30; θ3 is the starting angle of the low-pressure area of the flow distribution pair; θ4 is the ending angle of the low-pressure area of the flow distribution pair; p L is the tipping force generated by the oil film formed between the oil suction groove 25 and the cylinder block unit 30 on the cylinder block unit 30.

[0075] When the sealing band of the flow distribution pair is offset, the first offset value δ1 can be the offset amount of the high-pressure area of the flow distribution pair, and the second offset value δ2 can be the offset amount of the low-pressure area of the flow distribution pair. It can be obtained that r1 ′ = r1; r2 ′ = r2 - δ1; r3 ′ = r3 + δ2; r4 ′ = r4. The cylinder block unit 30 is mainly affected by the acting force of the oil film of the flow distribution pair on the end face. Among them, the pressure distribution in the high-pressure area of the flow distribution pair is:

[0076]

[0077] The pressure distribution in the low-pressure area of the flow distribution pair is:

[0078]

[0079] Then, the pressure distributions in the high-pressure and low-pressure regions of the flow distribution pair can be subjected to area integration to obtain the torque exerted by the oil film of the flow distribution pair on the cylinder block unit 30. First, the pressure distribution in the high-pressure region can be integrated over the area:

[0080]

[0081] Subsequently, after integrating the content in the curly brackets using the method of integration by parts and summarizing, the following can be obtained:

[0082]

[0083] After that, using the sum-to-product formula for trigonometric functions, the integration is continued to obtain the torque as:

[0084]

[0085] So far, the torque equation for the high-pressure region of the flow distribution pair has been obtained. For the torque equation of the low-pressure region, referring to the above process and solving the area integral according to the pressure distribution in the low-pressure region, the following can be obtained:

[0086]

[0087] Through the above calculations, it is convenient to determine the first offset value and the second offset value. Thus, the total overturning torque generated by the oil film of the flow distribution pair on the cylinder block unit 30 can be obtained as:

[0088]

[0089] From the above formula, it can be seen that by changing the magnitudes of the first offset value and the second offset value, the total overturning torque generated by the oil film of the flow distribution pair on the cylinder block unit 30 can be changed. Thus, the instantaneous torque exerted by the support layer 22 of the flow distribution plate unit 20 on the cylinder block unit 30 can be changed, realizing the balanced design of the overturning torque of the cylinder block unit 30, thereby reducing the lateral offset of the cylinder block unit 30 under the high-speed condition of the axial piston pump and improving the reliability of the axial piston pump.

[0090] In this embodiment, the axial piston pump further includes a valve unit. The valve unit includes a valve core body and a valve core spring; the valve unit is detachably connected to the flow distribution plate; the valve unit controls the on-off of the oil discharge port 24 and the oil suction port 23 respectively with the plunger cavity 32;

[0091] The calculation process of the first offset value and the second offset value is also related to the following formula:

[0092]

[0093] where L s is the axial length of the contact part between the cylinder block unit 30 and the drive shaft; F v is the thrust of the valve core body; F spis the pre-compression force of the spool spring. The calculation takes into account the torque generated by the drive shaft unit 70, thereby improving the accuracy of the calculated first offset value and second offset value.

[0094] In this embodiment, as Figure 4 shown, the absolute value of the first offset value is less than the absolute value of the second offset value. Since one end of the drive shaft unit 70 passes through the center of the flow distribution plate unit 20, the inner diameter side of the oil drain groove 26 needs to be offset toward the direction close to the center of the support layer 22, so that the offset distance of the inner diameter of the oil drain groove 26 is limited, while the outer diameter offset distance of the oil suction groove 25 is sufficient. Such a design can reasonably utilize the space on the support layer 22 and avoid affecting the decline of the oil film sealing effect formed between the support layer 22 and the cylinder block unit 30.

[0095] In this embodiment, as Figure 4 shown, the depth of the oil drain groove 26 is less than the depth of the oil drain port 24; the depth of the oil suction groove 25 is less than the depth of the oil suction port 23; the depth directions of the oil drain groove 26, the oil drain port 24, the oil suction groove 25, and the oil suction port 23 are perpendicular to the disk body 21. Thereby, the production cost can be reduced, and only a relatively thin thickness is required to achieve the effect of changing the oil film offset dimensions on the inner diameter side and outer diameter side of the oil drain groove 26 and the inner diameter side and outer diameter side of the oil suction groove 25.

[0096] In this embodiment, the support layer 22 and the disk body 21 can be integrally formed by three-dimensional printing. The flow distribution plate unit 20 formed by three-dimensional printing has high precision and good firmness of the combination between the support layer 22 and the disk body 21.

[0097] Those of ordinary skill in the art can understand that the above embodiments are specific cases for implementing the present disclosure, and in practical applications, various changes can be made in form and details without departing from the scope of the present disclosure.

Claims

1. An axial piston pump, characterized in that the axial piston pump includes: a housing unit; a valve plate unit, the valve plate unit is located within the housing unit; the valve plate unit includes a plate body and a support layer, the plate body has an oil discharge port and an oil suction port; both the oil discharge port and the oil suction port are arc-shaped and concentrically arranged; the inner diameter of the oil discharge port is equal to the inner diameter of the oil suction port; the outer diameter of the oil discharge port is equal to the outer diameter of the oil suction port; the support layer is fixedly connected to the plate body; the support layer has an oil discharge groove and an oil suction groove; the oil discharge groove is communicated with the oil discharge port; the oil discharge groove is arc-shaped and concentrically arranged with the oil discharge port; the central angle of the oil discharge port coincides with the central angle of the oil discharge groove; the inner diameter of the oil discharge groove is smaller than the inner diameter of the oil discharge port; the outer diameter of the oil discharge groove is equal to the outer diameter of the oil discharge port; the oil suction groove is communicated with the oil suction port; the oil suction groove is arc-shaped and concentrically arranged with the oil suction port; the central angle of the oil suction port coincides with the central angle of the oil suction groove; the outer diameter of the oil suction groove is larger than the outer diameter of the oil suction port; the inner diameter of the oil suction groove is equal to the inner diameter of the oil suction port; a cylinder block unit, the cylinder block unit is located within the housing unit; one end of the cylinder block unit is in contact with the support layer; the cylinder block unit is rotatably connected to the housing unit; the cylinder block unit includes a cylinder block body, and the cylinder block body has a plurality of plunger cavities; a plunger unit, there are a plurality of plunger units, the plunger unit includes a plunger rod and a plunger ball head; the plunger rod is slidably connected to the cylinder block unit; the plunger rods are arranged in one-to-one correspondence with the plunger cavities; the plunger rods are slidably arranged within the plunger cavities; the plunger ball head is integrally formed with the plunger rod; a slipper unit, the slipper unit is detachably connected to the plunger ball head; an inclined plate unit, the inclined plate unit is located within the housing unit; the inclined plate unit is detachably connected to the housing unit; the slipper unit abuts against the inclined plate unit; a drive shaft unit, the drive shaft unit drives the cylinder block unit to rotate; a central spring unit, the central spring unit drives the slipper unit to tightly abut against the inclined plate unit.

2. The axial piston pump according to claim 1, characterized in that the cylinder block unit and the valve plate unit form a flow distribution pair; the flow distribution pair is a high-pressure area at the position of the oil discharge groove; the flow distribution pair is a low-pressure area at the position of the oil suction groove; the inner radius of the oil discharge groove is the first radius r1'; the inner radius of the oil discharge port is the second radius r2'; the outer radius of the oil suction port is the third radius r3'; the outer radius of the oil suction groove is the fourth radius r4'; the difference between the first radius and the second radius is the first offset value δ1; the difference between the third radius and the fourth radius is the second offset value δ2; the first offset value and the second offset value are related to the following formula: M sx +M tx +M vx +M sh = 0; Wherein, M sx is the non-inertial force overturning moment generated by the acting force of the swash plate unit on the plunger rod on the cylinder block unit in the reference direction; the reference direction is the direction from the center of the oil drain groove to the middle of the oil drain groove; M tx is the inertial force overturning moment generated by the inertial force of the plunger rod movement on the cylinder block unit; M vx is the total overturning moment generated by the oil film of the flow distribution pair on the cylinder block unit, and is equal to the sum of the overturning moments generated by the oil films in the high-pressure area and the low-pressure area of the flow distribution pair on the cylinder block unit; M sh is the torque generated by the drive shaft unit on the cylinder block unit in the reference direction; r p is the radius of the cylinder block unit; L c is the distance from the intersection point of the swash plate unit and the drive shaft unit to the flow distribution plate unit; β is the inclination angle of the swash plate unit; is the pressure of the i-th plunger chamber; the circle formed by the distribution of multiple plunger units is the distribution circle; R is the radius of the distribution circle; is the angular displacement of the i-th plunger rod; F sp is the pre-tightening force of the central spring unit.

3. The axial piston pump according to claim 2, characterized in that the inertial force overturning moment generated by the inertial force of the plunger rod movement on the cylinder block unit is calculated according to the following formula: Wherein, N is the number of the plunger units; ω is the angular velocity.

4. An axial piston pump according to claim 3, wherein the first offset value is further related to the following formula: where M vHx is the tipping moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit when the first offset value is zero; θ1 is the starting angle of the high-pressure area of the flow distribution pair; θ2 is the ending angle of the high-pressure area of the flow distribution pair; p H is the load pressure; r1 is the inner radius of the inner sealing belt in the flow distribution pair; r2 is the outer radius of the inner sealing belt in the flow distribution pair; r3 is the inner radius of the outer sealing belt in the flow distribution pair; r4 is the outer radius of the outer sealing belt in the flow distribution pair; r1 ′ = r1; r2 ′ = r2 - δ1; r3 ′ = r3 + δ2; r4 ′ = r4.

5. An axial piston pump according to claim 4, wherein the first offset value is calculated according to the following formula: Wherein, M vHx′ is the overturning moment generated by the oil film in the high-pressure area of the flow distribution pair on the cylinder block unit when the first offset value is greater than zero; δ1 is the first offset value.

6. An axial piston pump according to claim 4, wherein the second offset value is further related to the following formula: where M vLx′ is the tipping moment generated by the oil film in the low-pressure area of the flow distribution pair on the cylinder block unit; θ3 is the starting angle of the low-pressure area of the flow distribution pair; θ4 is the ending angle of the low-pressure area of the flow distribution pair; p L is the tipping force generated by the oil film formed between the oil suction groove and the cylinder block unit on the cylinder block unit.

7. An axial piston pump according to claim 6, wherein the axial piston pump further comprises a valve unit, the valve unit includes a valve core body and a valve core spring; the valve unit is detachably connected to the valve plate; the valve unit controls the on-off of the oil discharge port and the oil suction port respectively communicating with the plunger cavity; the calculation processes of the first offset value and the second offset value are further related to the following formula: Among them, L s is the axial length of the contact part between the cylinder block unit and the drive shaft; F v is the thrust of the spool body; F sp is the pre-compression force of the spool spring.

8. An axial piston pump according to claim 7, wherein the absolute value of the first offset value is less than the absolute value of the second offset value.

9. An axial piston pump according to claim 1, wherein the depth of the oil discharge groove is less than the depth of the oil discharge port; the depth of the oil suction groove is less than the depth of the oil suction port; the depth directions of the oil discharge groove, the oil discharge port, the oil suction groove and the oil suction port are perpendicular to the disk body.

10. An axial piston pump according to claim 1, wherein the support layer and the disk body are integrally formed by three-dimensional printing.

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