Pump motor assembly for hydraulic piston pump and hydraulic piston pump including the assembly

Abstract

This application discloses a pump motor assembly for a hydraulic piston pump and a hydraulic piston pump including the assembly. The pump motor assembly includes: a pump barrel, which is configured as a hollow structure, with multiple flow channels for liquid flow arranged along the axial direction of the pump barrel and mounting holes arranged along the radial direction of the pump barrel in the barrel wall, and internally threaded connecting portions respectively included at both ends of the pump barrel; the mounting holes include a first mounting hole and a second mounting hole; a pump core, which is detachably disposed in the hollow structure of the pump barrel; a suction valve assembly disposed in the first mounting hole and selectively in fluid communication with the well fluid suction flow channels in the multiple flow channels; and a discharge valve assembly disposed in the second mounting hole and selectively in fluid communication with the well fluid discharge flow channels in the multiple flow channels.

Description

Technical Field

[0001] This application relates to the field of rodless oil and gas extraction equipment, and more specifically, to a pump motor assembly for a hydraulic piston pump and a hydraulic piston pump including the assembly. Background Technology

[0002] Hydraulic piston pumps are an important branch of rodless well drainage equipment and a highly efficient mechanical drainage method. They have proven irreplaceable in certain situations. With the increasing exploitation of oil and gas reservoirs such as shale gas and coalbed methane, the depth of oil and gas reservoirs is constantly increasing, and the amount of water accumulated in wells is gradually increasing. Conventional drainage equipment, such as foam lift and velocity tubing, are becoming increasingly inadequate for this situation. Hydraulic piston pumps, due to their high efficiency, applicability to deep wells and deviated wells, and mechanical drainage capabilities, are widely used in oil and gas field drainage operations.

[0003] As an important component of hydraulic piston pumps, the pump motor assembly plays a vital role. However, the existing hydraulic piston pumps have a simple assembly method for their components, and some components cannot be replaced individually when damaged. Utility Model Content

[0004] To address the aforementioned issues, this application provides a pump motor assembly for a hydraulic piston pump and a hydraulic piston pump including the assembly. This assembly enables various assembly methods among the components of the hydraulic piston pump. Furthermore, the easily damaged parts are designed to be disassembled, making disassembly and assembly simple, facilitating the replacement of easily damaged parts, and extending the service life of the components.

[0005] To achieve the above objectives, according to one aspect of this application, a pump motor assembly for a hydraulic piston pump is provided, wherein the pump motor assembly includes: a pump barrel, the pump barrel being configured as a hollow structure, having multiple flow channels for liquid flow arranged axially along the wall of the pump barrel and mounting holes arranged radially along the pump barrel, and having internally threaded connecting portions at both ends of the pump barrel, the mounting holes including a first mounting hole and a second mounting hole; a pump core, the pump core being detachably disposed within the hollow structure of the pump barrel; an intake valve assembly, the intake valve assembly being disposed in the first mounting hole and selectively in fluid communication with the well fluid intake flow channel in the multiple flow channels; and a discharge valve assembly, the discharge valve assembly being disposed in the second mounting hole and selectively in fluid communication with the well fluid discharge flow channel in the multiple flow channels.

[0006] Furthermore, both the first mounting hole and the second mounting hole are provided with internal threads. The suction valve assembly is installed in the first mounting hole through the internal thread of the first mounting hole, and the discharge valve assembly is installed in the second mounting hole through the internal thread of the second mounting hole.

[0007] Furthermore, a sealing ring groove is provided on the outer periphery of the pump core.

[0008] Furthermore, the first mounting hole and the second mounting hole are perpendicular to each other and neither penetrates the wall of the pump cylinder.

[0009] Furthermore, the inhalation valve assembly includes a valve body, a valve seat that cooperates with the valve body to form a receiving cavity, a valve ball and a guide ball holder disposed in the receiving cavity, wherein at least a portion of the valve ball is accommodated in the guide ball holder, and the guide ball holder is capable of moving back and forth along the inner surface of the valve body within the receiving cavity.

[0010] Furthermore, the discharge valve assembly includes a valve seat, a valve body that cooperates with the valve seat to form a receiving cavity, a valve ball and a guide ball holder disposed in the receiving cavity, wherein at least a portion of the valve ball is accommodated in the guide ball holder, and the guide ball holder is capable of moving back and forth along the inner surface of the valve seat within the receiving cavity.

[0011] Furthermore, the inhalation valve assembly and the discharge valve assembly also include a spring disposed between the valve body and the guide ball support.

[0012] Furthermore, the guide ball holder includes: a body portion, the center of which is provided with a receiving hole that passes through the body portion, and the valve ball is received in the receiving hole; a plurality of protrusions that extend outward from the circumference of the body portion along the radial direction of the body portion, and the protrusions have a guide surface that guides the guide ball holder to move in the receiving cavity; and a plurality of liquid channels disposed between two adjacent protrusions.

[0013] Furthermore, both the intake valve assembly and the discharge valve assembly have threaded portions on their outer surfaces.

[0014] Furthermore, the pump motor assembly also includes a plug that seals the first mounting hole or the second mounting hole.

[0015] Furthermore, the structure and dimensions of the connecting parts at both ends of the pump cylinder are exactly the same.

[0016] Furthermore, the pump motor assembly is provided with multiple pump cores, the multiple pump cores having a hollow structure, and the multiple pump cores having the same outer diameter and different inner diameters.

[0017] According to another aspect of this application, a hydraulic piston pump is provided, wherein the hydraulic piston pump includes any of the pump motor assemblies described above.

[0018] According to this application, by providing threaded connecting portions at both ends inside the pump barrel, different components can be connected to these ends. Furthermore, by arranging the valve assembly along the radial direction of the pump barrel, the pump motor assembly structure is made more compact, and the valve assembly diameter can be increased, reducing liquid flow resistance. Moreover, this arrangement allows the valve assembly to communicate directly with the pump chamber without requiring a connecting flow channel, reducing the flow channel volume and thus improving adaptability to gas-containing conditions, increasing pump volumetric efficiency, and reducing the likelihood of airlock. In addition, by designing the pump core and pump barrel as separate structures, replacement of the pump core can be easily performed after the inner bore wears down. Attached Figure Description

[0019] Figure 1A and Figure 1B Two different cross-sectional views along the axis of the pump motor assembly according to embodiments of this application are shown. Figure 1A The suction valve assembly and well fluid suction flow channel are shown. Figure 1B The discharge valve assembly and well fluid discharge channel are shown;

[0020] Figure 2A and Figure 2B Perspective views of the pump barrel of the pump motor assembly according to embodiments of this application are shown respectively;

[0021] Figure 3A It shows along Figure 2A and Figure 2B The diagram shows a cross-sectional view taken along the axis of the pump cylinder.

[0022] Figure 3B It shows along Figure 3A A cross-sectional view taken from line AA;

[0023] Figures 4A to 4E Cross-sectional views are shown of the power fluid flow channel, waste power flow channel, motor inlet flow channel, well fluid discharge flow channel, and well fluid intake flow channel arranged axially along the pump barrel; and

[0024] Figure 5 It shows Figure 1A and Figure 1B A 3D view of the pump core;

[0025] Figure 6A and Figure 6B A perspective view and a cross-sectional view of a discharge valve assembly according to an embodiment of this application are shown;

[0026] Figure 7A and Figure 7BA perspective view and a cross-sectional view of an inhalation valve assembly according to an embodiment of this application are shown; and

[0027] Figure 8 A guide ball support structure in an inhalation valve assembly / discharge valve assembly according to an embodiment of this application is shown. Detailed Implementation

[0028] The specific embodiments of this application are described in detail below. The specific embodiments described herein are for illustration and explanation only, and are not intended to limit the scope of this invention.

[0029] The embodiments of this application are described below with reference to the accompanying drawings. Although exemplary embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application can be thoroughly understood and that the scope of this invention can be fully conveyed to those skilled in the art.

[0030] Figure 1A and Figure 1B Two different cross-sectional views along the axis of the pump motor assembly according to an embodiment of this application are shown, each illustrating a different cross-sectional flow path.

[0031] like Figure 1A and 1B As shown, the pump motor assembly according to this application includes a pump barrel 3001, a pump core 3003 disposed in the pump barrel 3001, a discharge valve assembly 3004, and a suction valve assembly 3005.

[0032] The discharge valve assembly 3004 is selectively in fluid communication with the well fluid discharge channel 3007 arranged along the axial direction of the pump barrel 3001, and the suction valve assembly 3005 is selectively in fluid communication with the well fluid suction channel 3006 arranged along the axial direction of the pump barrel 3001.

[0033] Furthermore, as shown in the figure, both the discharge valve assembly 3004 and the suction valve assembly 3005 are arranged radially along the pump barrel 3001. According to this application, due to the radial arrangement of the valve assemblies, the flow area of ​​the check valve can be increased within the same external dimensions.

[0034] If the valve assembly is placed axially, increasing the flow orifice diameter of the valve assembly will increase the overall outer diameter of the valve assembly, further increasing the outer diameter of the entire pump motor assembly and affecting its applicability to small wellheads. However, according to this application, the valve assembly is placed radially, thus increasing the flow area of ​​the valve assembly without affecting the outer diameter of the pump motor assembly.

[0035] Below, we will refer to the appendix. Figures 6A to 8Detailed description of an embodiment of the present application of the discharge valve assembly 3004 and the intake valve assembly 3005.

[0036] like Figure 6B As shown, the discharge valve assembly 3004 includes a valve seat 3004-1, a valve ball 3004-2, a guide ball support 3004-3, a spring 3004-4, a valve body 3004-5, and a threaded portion 3004-7 provided on the outer surface of the valve seat 3004-1. Furthermore, a sealing surface 3004-6 is formed on the outer surface of the valve body 3004-5 to engage with the pump barrel 3001.

[0037] like Figure 6A As shown, a structure is formed on the top of the discharge valve assembly 3004 to facilitate the application of torque to it using a tool, thereby enabling the discharge valve assembly to be tightened by the tool, and thus the valve body 3004-5 of the discharge valve assembly 3004 and the pump barrel 3001 form a surface seal.

[0038] like Figure 6B As shown, valve seat 3004-1 and valve body 3004-5 cooperate with each other, and a receiving cavity is formed inside valve seat 3004-1 and valve body 3004-5. Valve ball 3004-2, guide ball support 3004-3, and spring 3004-4 are housed in the receiving cavity. Spring 3004-4 is supported in valve body 3004-5, and guide ball support 3004-3 is mounted in valve seat 3004-1 by spring 3004-4, and abuts against the inner surface of valve seat 3004-1. Guide ball support 3004-3 can move back and forth along the inner surface of valve seat 3004-1 by spring 3004-4. Valve ball 3004-2 is disposed between valve seat 3004-1 and guide ball support 3004-3, and is housed in guide ball support 3004-3.

[0039] like Figure 8 As shown, the guide ball holder 3004-3 of the discharge valve assembly 3004 has a body portion 3004-8. A receiving hole 3004-11 is provided in the center of the body portion 3004-8, through which the valve ball 3004-2 can be accommodated. Multiple protrusions 3004-9 extend outward from the circumference of the body portion 3004-8 along the radial direction of the body portion 3004-8. A liquid passage 3004-12 for liquid passage is formed between two adjacent protrusions 3004-9. Each protrusion 3004-9 is provided with a guide surface 3004-10 to guide the guide ball holder 3004-3 in the receiving cavity.

[0040] like Figure 6BAs shown, the guide surface 3004-10 of the guide ball holder 3004-3 abuts against the inner surface of the valve seat 3004-1, and the guide ball holder 3004-3 is disposed in the valve seat 3004-1 by a spring 3004-4. Thus, the guide ball holder 3004-3 can simultaneously guide both the valve ball 3004-2 and the spring 3004-4, ensuring the service life and timely opening and closing of the discharge valve assembly. Furthermore, the presence of the guide ball holder minimizes the length of the discharge valve assembly.

[0041] Figure 7A and Figure 7B The structure of an inhalation valve assembly 3005 according to this application is shown, which is similar to the structure of an exhaust valve assembly 3004.

[0042] Specifically, such as Figure 7B As shown, the suction valve assembly 3004 includes a valve body 3005-1, a spring 3005-2, a guide ball support 3005-3, a valve ball 3005-4, a valve seat 3005-5, and a threaded portion 3005-7 provided on the outer surface of the valve seat 3005-1. Furthermore, a sealing surface 3005-6 is formed on the outer surface of the valve seat 3005-5 to engage with the pump barrel 3001.

[0043] like Figure 7A As shown, a structure is formed on the top of the suction valve assembly 3005 to facilitate the application of torque to it using a tool, so that the suction valve assembly can be tightened by the tool, thereby forming a surface seal between the valve seat 3005-5 of the suction valve assembly 3005 and the pump barrel 3001.

[0044] like Figure 7B As shown, valve body 3005-1 and valve seat 3005-5 cooperate with each other, and a receiving cavity is formed inside valve body 3005-1 and valve seat 3005-5. Spring 3005-2, guide ball support 3005-3, and valve ball 3005-4 are housed in the receiving cavity. A portion of valve ball 3005-4 is disposed on valve seat 3005-5, and another portion of valve ball 3005-4 is disposed in guide ball support 3005-3, which abuts against the inner surface of valve body 3005-1. One end of spring 3005-2 is supported on guide ball support 3005-3, and the other end is supported on valve body 3005-1. Through spring 3005-2, guide ball support 3005-3 can move back and forth on the inner surface of valve body 3005-1.

[0045] The structure of the guide ball support 3005-3 of the intake valve assembly 3005 is similar to that of the guide ball support 3004-3 of the discharge valve assembly 3004. Except that the guide ball support of the intake valve assembly 3005 uses the reference numerals starting with 3005, it uses the same reference numerals as the guide ball support of the discharge valve assembly 3004. This will not be described in detail here.

[0046] like Figure 7B As shown, the guide surface 3005-10 of the guide ball support 3005-3 abuts against the inner surface of the valve body 3005-1. One end of the spring 3005-2 is supported on the guide ball support 3005-3, and the other end is supported on the valve body 3005-1. Thus, the guide ball support 3005-3 can simultaneously guide both the valve ball 3005-4 and the spring 3005-2, ensuring the service life and timely opening and closing of the suction valve assembly. Furthermore, the guide ball support minimizes the length of the suction valve assembly.

[0047] Return to Figure 2A and Figure 2B , Figure 2A and Figure 2B The three-dimensional structure of the pump barrel 3001 according to an embodiment of this application is shown. To illustrate the structure of the pump barrel more clearly, Figure 2A The pump barrel structure is shown in perspective view, and different flow channels arranged along the pump barrel axis are shown in different colors. Figure 3A and Figure 3B Cross-sectional views taken along the axial direction of the pump barrel and along the radial direction of the pump barrel and along line AA are shown respectively. Figures 4A to 4E Cross-sectional views of different flow channels arranged in the pump barrel are shown.

[0048] As shown in the figure, the pump cylinder 3001 is a hollow structure. Multiple flow channels for liquid flow are arranged along the axial direction of the pump cylinder 3001 within its wall. Figure 2A These flow channels are indicated by different colors to achieve different flow channel conduction functions and structural connection functions. Furthermore, as shown in the figure, these flow channels are arranged along the circumferential direction of the pump barrel 3001. According to this application, as... Figure 2A As shown, the pump barrel 3001 is circumferentially provided with a power fluid flow channel (red) extending axially along the pump barrel, a waste power fluid flow channel (yellow) allowing the power fluid to flow out of the pump, a motor chamber inlet flow channel (gray) allowing the power fluid to flow into the motor chamber, a well fluid discharge flow channel (purple) allowing the well fluid to be discharged from the pump, and a well fluid suction flow channel (green) allowing the well fluid to flow into the pump. Waste power fluid refers to the high-pressure power fluid that returns to the surface after driving the piston movement in the pump core.

[0049] like Figure 3BAs shown, it illustrates a cross-sectional view of the various flow channels 3011 on the pump barrel as described above (i.e., the power fluid flow channel (red), the waste power fluid flow channel (yellow), the motor inlet flow channel (grey), the well fluid discharge flow channel (purple), and the well fluid intake flow channel (green)). Figure 4A As shown, it illustrates a cross-sectional view of the power fluid flow channel in the pump barrel 3001. (As shown...) Figure 4B As shown, it illustrates a cross-sectional view of the waste power flow channel in pump casing 3001. (As...) Figure 4C As shown, it illustrates a cross-sectional view of the flow channel in the motor inlet chamber of the pump barrel 3001. (As shown...) Figure 4D As shown, it illustrates a cross-sectional view of the well fluid discharge channel in pump casing 3001. (As...) Figure 4E As shown, it illustrates a cross-sectional view of the well fluid intake channel in the pump barrel 3001.

[0050] like Figure 2B As shown, mounting holes 3009 are provided radially in the wall of the pump cylinder 3001. According to one embodiment of this application, the pump cylinder 3001 is provided with two mounting holes 3009, namely, a first mounting hole and a second mounting hole.

[0051] According to one embodiment of this application, both the first mounting hole and the second mounting hole are provided with internal threads. The threaded portion 3005-7 of the suction valve assembly 3005 is installed in the first mounting hole 3009 by engaging with the internal thread of the first mounting hole 3009; the suction valve assembly 3005 and the first mounting hole 3009 are designed for a transition fit. The threaded portion 3005-7 of the discharge valve assembly 3004 is installed in the second mounting hole 3009 by engaging with the internal thread of the second mounting hole 3009. The discharge valve assembly 3004 and the second mounting hole 3009 are designed for a transition fit. With this configuration, the valve assemblies can be assembled independently, thereby facilitating the disassembly and assembly of the valve assemblies and enabling sealing tests.

[0052] Install the valve assembly into position 3008 of pump cylinder 3001 through the first mounting hole or the second mounting hole (e.g., Figure 3A After (as shown), it can be done at position 3015 of pump cylinder 3001 (as shown). Figure 3A As shown, install the plug 3002 to seal it.

[0053] Furthermore, according to one embodiment of this application, such as Figure 3A As shown, the two mounting holes are perpendicular to each other and neither penetrates the wall of the pump cylinder 3001.

[0054] like Figure 3AAs shown, the pump cylinder 3001 also has a first protrusion 3013 and a second protrusion 3014 that are oppositely arranged and protrude toward the hollow structure. A first mounting hole passes through the first protrusion 3013 and the second protrusion 3014. The first end of the pump core 3003 can abut against the first protrusion 3013 and the second protrusion 3014.

[0055] Similarly, the cylinder wall of pump cylinder 3001 is also provided with a third protrusion and a fourth protrusion that are oppositely arranged and protrude toward the hollow structure (e.g. Figure 1A (As shown in 1B), the second mounting hole penetrates the third protrusion and the fourth protrusion. The first end of the pump core 3003 can abut against the third and fourth protrusions.

[0056] The pump cylinder 3001 has internal threads 3010 at both ends (e.g., ...). Figure 3A The connection portion (shown) is shown. According to the embodiments of this application, the structure and dimensions of the connection portions at both ends of the pump barrel 3001 are exactly the same. Therefore, when components (e.g., multi-functional connectors) are inserted into the connection portions at both ends of the pump barrel 3001, rotating the pump barrel 3001 180 degrees can achieve different assembly structures.

[0057] According to this application, since the pump barrel has multiple flow channels extending axially along its circumference, if the valve assembly structure is arranged axially, the usable space is affected by the pump barrel wall thickness and the surrounding flow channel structure. Therefore, it is difficult to achieve a large size for the valve assembly, resulting in a smaller valve assembly diameter and higher flow resistance. For the same pump barrel size, arranging the valve assembly radially requires more usable space than arranging it axially. Therefore, the radial arrangement of the valve assembly with guide ball support, compared to the axial arrangement, not only reduces the length of the valve assembly but also makes the structure more compact and allows for a larger valve assembly diameter, reducing liquid flow resistance. Furthermore, this arrangement allows the valve assembly to be directly connected to the pump chamber without needing to connect the flow channels, reducing the flow channel volume and thus improving adaptability to gas-containing conditions, increasing pump volumetric efficiency, and reducing the risk of airlock.

[0058] like Figure 5 As shown, a pump core 3003 according to an embodiment of this application is illustrated. The pump core 3003 has a hollow structure for accommodating a piston and cooperating with the outer circle of the piston. By sealing the piston with the inner hole of the pump core 3003, the interior of the pump core 3003 can be divided into two piston chambers.

[0059] Furthermore, according to one embodiment of this application, the pump core 3003 is detachably disposed in the hollow structure of the pump barrel 3001.

[0060] By designing the pump core and pump barrel as separate structures, it is easy to replace the pump core after the inner bore is worn.

[0061] According to one embodiment of this application, a plurality of detachable pump cores may be provided, each pump core having the same outer diameter that can be inserted into a pump barrel, but having different inner diameters to accommodate a piston. Thus, by replacing pump cores with different inner diameters, the diameter of the accommodated piston can be changed, and the diameter of the piston chamber can also be changed without replacing the pump barrel.

[0062] Therefore, according to the detachable pump core of this application, when the piston rod diameter remains unchanged and the piston diameter changes, the area ratio of the rod chamber to the rodless chamber of the piston cavity will also change accordingly. Therefore, the area ratio of the rod chamber to the rodless chamber of the hydraulic piston pump can be changed by replacing the piston and the pump core.

[0063] Furthermore, according to one embodiment of this application, a sealing ring groove 3012 is provided on the outer side of the pump core 3003 for installing a sealing element, thereby achieving a seal between the pump core 3003 and the inner hole of the pump barrel 3001.

[0064] According to this application, by providing threaded connecting parts at both ends inside the pump barrel, different components can be connected to these two ends. Furthermore, the connecting parts at both ends of the pump barrel have the same structure and dimensions, allowing for different assembly structures to be achieved by rotating the pump barrel 180 degrees. Moreover, by arranging the valve assembly along the radial direction of the pump barrel, not only is the structure of the pump motor assembly more compact, but the diameter of the valve assembly can also be increased, reducing liquid flow resistance. In addition, this arrangement allows the valve assembly to communicate directly with the pump chamber without requiring a connecting flow channel, reducing the flow channel volume, thereby improving adaptability to gas-containing conditions, increasing pump volumetric efficiency, and reducing the likelihood of airlock.

[0065] In addition, by designing the pump core and pump barrel as separate structures, it is easy to replace the pump core after the inner bore is worn.

[0066] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A pump motor assembly for a hydraulic piston pump, characterized by The pump motor assembly includes: The pump barrel is configured as a hollow structure. In the barrel wall, multiple flow channels for liquid flow are provided along the axial direction of the pump barrel and mounting holes are provided along the radial direction of the pump barrel. The pump barrel also includes internally threaded connecting parts at both ends. The mounting holes include a first mounting hole and a second mounting hole. Pump core, wherein the pump core is disposed in a detachable manner within the hollow structure of the pump barrel; A suction valve assembly, wherein the suction valve assembly is disposed in the first mounting hole and is selectively in fluid communication with the well fluid suction channel in the plurality of flow channels; and A discharge valve assembly is disposed in the second mounting hole and is selectively in fluid communication with the well fluid discharge channel in the plurality of flow channels.

2. The pump motor assembly of claim 1, wherein, Both the first mounting hole and the second mounting hole are provided with internal threads. The suction valve assembly is installed in the first mounting hole through the internal thread of the first mounting hole, and the discharge valve assembly is installed in the second mounting hole through the internal thread of the second mounting hole.

3. The pump motor assembly of claim 1, wherein, The pump core has a sealing ring groove on its outer periphery.

4. The pump motor assembly of any one of claims 1-3, wherein, The first mounting hole and the second mounting hole are perpendicular to each other and neither penetrates the wall of the pump cylinder.

5. The pump motor assembly of claim 1, wherein, The inhalation valve assembly includes a valve body, a valve seat that cooperates with the valve body to form a receiving cavity, a valve ball and a guide ball holder disposed in the receiving cavity, wherein at least a portion of the valve ball is accommodated in the guide ball holder, and the guide ball holder is capable of reciprocating along the inner surface of the valve body within the receiving cavity.

6. The pump motor assembly of claim 1, wherein, The discharge valve assembly includes a valve seat, a valve body that cooperates with the valve seat to form a receiving cavity, a valve ball and a guide ball holder disposed in the receiving cavity, wherein at least a portion of the valve ball is accommodated in the guide ball holder, and the guide ball holder is capable of reciprocating along the inner surface of the valve seat within the receiving cavity.

7. The pump motor assembly of claim 5 or 6, wherein, The inhalation valve assembly and the discharge valve assembly also include a spring disposed between the valve body and the guide ball support.

8. The pump motor assembly of claim 5 or 6, wherein, The guide ball holder includes: a body portion, the center of which is provided with a receiving hole that passes through the body portion, and the valve ball is received in the receiving hole; a plurality of protrusions that extend outward from the circumference of the body portion along the radial direction of the body portion, and the protrusions have a guide surface that guides the guide ball holder to move in the receiving cavity; and a plurality of liquid channels disposed between two adjacent protrusions.

9. The pump motor assembly of claim 2, wherein, Both the inhalation valve assembly and the discharge valve assembly have threaded portions on their outer surfaces.

10. The pump motor assembly of any one of claims 1-3, wherein, The pump motor assembly also includes a plug that seals the first mounting hole or the second mounting hole.

11. The pump motor assembly of any one of claims 1 to 3, wherein, The structure and dimensions of the connecting parts at both ends of the pump cylinder are exactly the same.

12. The pump motor assembly of claim 4, wherein, The pump motor assembly is provided with a plurality of pump cores, the plurality of pump cores having a hollow structure and having the same outer diameter and different inner diameters.

13. A hydraulic piston pump characterized by The hydraulic piston pump includes a pump motor assembly according to any one of claims 1 to 12.

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