Patent Description:
At present, during the operation of the pump body assembly, the piston sleeve is prone to rotate eccentrically and aslant, which causes friction between the piston sleeve, the cylinder, and the piston, thus seriously affecting working efficiency and performance of the pump body assembly. Document <CIT> discloses a driving main shaft and a compressor. Document <CIT> discloses a rotating piston compressor.

The main objective of the present invention is to provide a pump body assembly, fluid machinery, and a heat exchange device, to solve the problem in the prior art that the working efficiency of the pump body assembly is affected because the piston sleeve of the pump body assembly is prone to rotate eccentrically.

In order to achieve the objective above, according to one aspect of the present invention, a pump body assembly is provided and includes: at least two structure members, a cylinder arranged between the two structure members, and a piston assembly arranged in the cylinder; the piston assembly includes a piston sleeve and a piston slidably arranged in the piston sleeve; an upper end surface of the piston sleeve fits and is limited by a lower end surface of one structure member disposed above the piston sleeve to prevent the piston sleeve from moving in a radial direction relative to the one structure member.

A position-limiting protrusion is provided on a lower end surface of the piston sleeve; the position-limiting protrusion fits another structure member located below the cylinder to prevent the piston sleeve from moving in the radial direction relative to the other structure member.

The at least two structure members comprises a lower flange and a lower position-limiting plate; the lower position-limiting plate and the lower flange are both disposed below the cylinder; the lower position-limiting plate is disposed between the cylinder and the lower flange; and the position-limiting protrusion is limited and stopped by the lower position-limiting plate to prevent the piston sleeve from moving in the radial direction relative to the lower position-limiting plate. A second extended part is provided on the surface of the lower flange, and the surface of the lower flange faces the piston sleeve; the second extended part limits and stops the position-limiting protrusion to prevent the piston sleeve from moving in the radial direction relative to the lower flange.

The second extended part is located inside the position-limiting protrusion.

The position-limiting protrusion extends into a central hole of the lower position-limiting plate, fits and is limited by an inner surface of the central hole of the lower position-limiting plate.

Further, the one structure member disposed above the piston sleeve is an upper flange.

Further, the upper end surface of the piston sleeve has a first extended part; the lower end surface of the upper flange has a concave part; and the first extended part extends into the concave part, and is limited and stopped by the concave part in a radial direction of the piston sleeve.

Further, the lower end surface of the upper flange has a position-limiting part extending toward the piston sleeve, and the piston sleeve is limited and stopped by the position-limiting part to prevent the piston sleeve from moving in a radial direction relative to the upper flange.

Further, the position-limiting part extends into the piston sleeve, limits and stops an inner surface of the piston sleeve.

Further, the upper end surface of the piston sleeve has a first position-limiting groove, and the position-limiting part extends into the first position-limiting groove to limit and stop the first position-limiting groove.

Further, the at least two structure members include a lower flange located below the piston assembly; a position-limiting protrusion is provided on a surface of the piston sleeve, and the surface of the piston sleeve faces the lower flange; the pump body assembly further includes a lower friction-reducing ring arranged inside the cylinder; the lower friction-reducing ring has a central hole; and the position-limiting protrusion extends into the central hole, and is limited and stopped by the lower flange to prevent the piston sleeve from moving in the radial direction relative to the lower flange.

Further, a second position-limiting groove is provided on a surface of the lower flange, and the surface of the lower flange faces the piston sleeve; the position-limiting protrusion extends into the second position-limiting groove to prevent the piston sleeve from moving in the radial direction relative to the lower flange.

Further, the second extended part is located outside the position-limiting protrusion.

Further, the position-limiting protrusion is a protruding ring extending toward the lower flange, and the protruding ring and the piston sleeve are coaxially arranged.

Further, the position-limiting protrusion includes a plurality of protruding platforms extending toward the lower flange, and the plurality of protruding platforms are arranged at intervals along a circumference of the piston sleeve.

Further, the other structure member located below the cylinder is the lower flange.

Further, a surface of the lower position-limiting plate, which faces a surface of the piston sleeve, has a third position-limiting groove, and the position-limiting protrusion extends into the third position-limiting groove, and is limited and stopped by the third position-limiting groove.

Further, the at least two of the structure members include the lower flange located below the piston assembly, and the pump body assembly further includes a rotation shaft; the rotation shaft passes through the upper flange, the piston sleeve and the lower flange in sequence; and the rotation shaft, the upper flange, and the lower flange are arranged coaxially.

According to another aspect of the present invention, fluid machinery is provided and includes the pump body assembly above.

According to another aspect of the present invention, a heat exchange device is provided and includes the fluid machinery.

In the technical solution applying the present invention, the pump body assembly includes the at least two structure members, the cylinder and the piston assembly. Where the cylinder is arranged between the two structure members. The piston assembly is arranged in the cylinder. The piston assembly includes the piston sleeve and the piston slidably arranged in the piston sleeve. The upper end surface of the piston sleeve fits and is limited by the lower end surface of the structure member disposed above the piston sleeve, so as to prevent the piston sleeve from moving in the radial direction relative to the structure member. In this case, during the operation of the pump body assembly, the upper end of the piston sleeve is limited and supported by the structure member disposed above it, thereby preventing the piston sleeve from moving in the radial direction during operation, ensuring the piston sleeve to rotate normally, solving the problem in the prior art that the working efficiency of the pump body assembly is affected because the piston sleeve of the pump body assembly is prone to rotate eccentrically, and improving the operation reliability and the working performance of the pump body assembly.

The accompanying drawings attached to the specification form a part of the present invention and are intended to provide a further understanding of the present invention. The illustrative embodiments of the present invention and the description thereof are used for explanations of the present invention, and do not constitute improper limitations of the present invention. In the accompanying drawings:.

The above-mentioned figures include following reference signs:
<NUM>. upper flange; <NUM>. concave part; <NUM>. position-limiting part; <NUM>. lower flange; <NUM>. second position-limiting groove; <NUM>. second extended part; <NUM>. lower position-limiting plate; <NUM>. cylinder; <NUM>. rotation shaft; <NUM>. piston sleeve; <NUM>. first extended part; <NUM>. first position-limiting groove; <NUM>. position-limiting protrusion; <NUM>. step surface; <NUM>. piston; <NUM>. lower friction-reducing ring.

It should be noted that the embodiments in the present invention and the features in the embodiments can be combined with each other if no conflicts occur. The present invention will be described in detail below with reference to the accompanying drawings in combination with the embodiments.

It should be noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by the ordinary skilled in the art of the present invention.

In the present invention, unless stated to the contrary, the orientation words such as "up, down" are usually used to refer to the orientations shown in the drawings, or to the component itself in the vertical, orthographic or gravity direction. Similarly, in order to facilitate the understanding and the description, "left, right" are usually used to refer to the left and right shown in the drawings, and "inner" and "outer" refer to "inner" and "outer" relative to the outline of each component itself. However, the orientation words are not given to limit the present invention.

In order to solve the problem in the prior art that the working efficiency of the pump body assembly is affected because the piston sleeve of the pump body assembly is prone to rotate eccentrically, the present invention provides a pump body assembly, fluid machinery, and a heat exchange device.

As shown in <FIG>, the pump body assembly includes two structure members, a cylinder <NUM> and a piston assembly. The cylinder <NUM> is arranged between the two structure members. The piston assembly is arranged in the cylinder <NUM>. The piston assembly includes a piston sleeve <NUM> and a piston <NUM> slidably arranged in the piston sleeve <NUM>. An upper end surface of the piston sleeve <NUM> fits and is limited by a lower end surface of the structure member disposed above the piston sleeve <NUM>, so as to prevent the piston sleeve <NUM> from moving in a radial direction relative to the structure member.

In the technical solution applying this embodiment, during the operation of the pump body assembly, the upper end of the piston sleeve <NUM> is limited and supported by the structure member disposed above it, thereby preventing the piston sleeve <NUM> from moving in the radial direction during operation, ensuring the piston sleeve <NUM> to rotate normally, solving the problem in the prior art that the working efficiency of the pump body assembly is affected because the piston sleeve of the pump body assembly is prone to rotate eccentrically, and improving the operation reliability and the working performance of the pump body assembly.

In this embodiment, the structure member disposed above the piston sleeve <NUM> is an upper flange <NUM>.

As shown in <FIG>, the upper end surface of the piston sleeve <NUM> has a first extended part <NUM>; the lower end surface of the upper flange <NUM> has a concave part <NUM>; and the first extended part <NUM> extends into the concave part <NUM>, and is limited and stopped by the concave part <NUM> in a radial direction of the piston sleeve <NUM>. In this case, the first extended part <NUM> of the piston sleeve <NUM> extends into the concave part <NUM> of the upper flange <NUM>, realizing, by the upper flange <NUM>, the position limitation to the piston sleeve <NUM> in the radial direction. During the operation of the pump body assembly, the convex part <NUM> limits and stops the first extended part <NUM>, which ensures that the first extended part <NUM> rotates in the convex part <NUM>, thereby preventing the first extended part <NUM> from moving in the radial direction, realizing, by the upper flange <NUM>, the position limitation and a support for the upper end of the piston sleeve <NUM>, preventing the piston sleeve <NUM> from rotating eccentrically and aslant, ensuring the pump body assembly to operate normally, and improving the working reliability of the pump body assembly.

In this embodiment, the first extended part <NUM> and the concave part <NUM> are ring-shaped, and the first extended part <NUM>, the concave part <NUM>, and the piston sleeve <NUM> are coaxially arranged. In this case, the above arrangement enables the piston sleeve <NUM> to rotate relative to the upper flange <NUM>, thereby ensuring the operation reliability of the pump body assembly. The piston sleeve <NUM> and the upper flange <NUM> are eccentrically arranged, and an eccentricity thereof is an eccentricity e of the pump body assembly. In this case, the above arrangement enables the first extended part <NUM> of the piston sleeve <NUM> to rotate in the concave part <NUM> of the upper flange <NUM> and rotate around a central axis of the piston sleeve <NUM> (or around a central axis of the concave part <NUM>), thus ensuring reliability of the position limitation and the support provided by the upper flange for the piston sleeve <NUM>.

It should be noted that the first extended part <NUM> is not limited to such a structure. Optionally, the first extended part <NUM> is a double-layered ring-shaped structure, and at least one layer of the ring-shaped structure is limited and stopped by an inner groove wall or an outer groove wall of the concave part <NUM>. In this case, the above arrangement makes the structure of the first extended part <NUM> more diversified, thereby making the processing and manufacturing of the piston sleeve <NUM> easier and simpler, and reducing labor intensity of staff.

In this embodiment, the concave part <NUM> is a groove. The above-mentioned structure is simple, and easy to process and implement.

In this embodiment, a width of the groove is greater than a thickness of the first extended part <NUM>. In this case, the above arrangement ensures that the first extended part <NUM> is located in the groove, thereby ensuring that the groove can limit and stop the first extended part <NUM>, improving the reliability of the position limitation provided by the upper flange <NUM> for the piston sleeve <NUM>, and improving the operation reliability of the pump body assembly.

In this embodiment, there is a first predetermined distance between an inner groove wall of the groove and a side surface of the first extended part <NUM> proximate to the center of the piston sleeve <NUM>, and the first predetermined distance is greater than or equal to <NUM>, and less than or equal to <NUM>. Specifically, the inner groove wall of the groove limits and stops the side surface of the first extended part <NUM> proximate to the center of the piston sleeve <NUM>, preventing a radial displacement therebetween. Moreover, in order to ensure that the piston sleeve <NUM> can rotate normally, the first predetermined distance, between the inner groove wall of the groove and the side surface of the first extended part <NUM> proximate to the center of the piston sleeve <NUM>, is set, which not only ensures the groove to radially limit the position of the first extended part <NUM>, but also enables the first extended part <NUM> to rotate relative to the groove, thereby improving the operation reliability of the pump body assembly.

In this embodiment, the convex part <NUM> and the upper flange <NUM> are eccentrically arranged, and the eccentricity is e. In this case, the eccentricity of the pump body assembly is determined in the above manner, making it easier to guarantee the eccentricity of the pump body assembly, and the determination of the eccentricity e is more reliable and simple.

As shown in <FIG>, the pump body assembly further includes a lower flange <NUM> and a rotation shaft <NUM>. The lower flange <NUM> is disposed below the piston assembly. The rotation shaft <NUM> passes through the upper flange <NUM>, the piston sleeve <NUM>, and the lower flange <NUM> in sequence; and the rotation shaft <NUM>, the upper flange <NUM>, and the lower flange <NUM> are arranged coaxially. During the operation of the pump body assembly, the rotation shaft <NUM> rotates around the central axis of the upper flange <NUM>; the piston sleeve <NUM> rotates around the central axis of the concave part <NUM>; the piston <NUM> only reciprocates relative to the piston sleeve <NUM>; and the piston <NUM> reciprocates relative to the rotation shaft <NUM>. The two reciprocating motions are perpendicular to each other, that is, the operation of the pump body assembly follows the principle of the cross slide block type mechanism. With the reciprocating motion between the piston <NUM> and the piston sleeve <NUM>, the volumes of two cavities formed between a curved surface of the head of the piston <NUM>, the inner surface of the cylinder <NUM>, and the guiding hole of the piston sleeve <NUM> gradually change, thereby completing a process of intake, compression and exhausting.

The present invention further provides fluid machinery (not shown), including the above-mentioned pump body assembly. Optionally, the fluid machinery is a compressor.

The present invention further provides a heat exchange device (not shown), including the above-mentioned fluid machinery. Optionally, the heat exchange device is an air conditioner.

The pump body assembly of the second embodiment differs from that of the first embodiment in that structures of the upper flange <NUM>, the piston sleeve <NUM>, and the lower flange <NUM> are different respectively.

As shown in <FIG>, the lower end surface of the upper flange <NUM> has a position-limiting part <NUM> extending toward the piston sleeve <NUM>, and the piston sleeve <NUM> is limited and stopped by the position-limiting part <NUM>, so as to prevent the piston sleeve <NUM> from moving in a radial direction relative to the upper flange <NUM>. Where, the position-limiting part <NUM> extends into the piston sleeve <NUM>, limits and stops an inner surface of the piston sleeve <NUM>. In this case, the position-limiting part <NUM> of the upper flange <NUM> extends into the piston sleeve <NUM>, limits and stops the inner surface of the piston sleeve <NUM>, thereby realizing, by the upper flange <NUM>, a position limitation to the piston sleeve <NUM> in the radial direction. During the operation of the pump body assembly, the inner surface of the piston sleeve <NUM> is limited and stopped by the position-limiting part <NUM> to prevent the piston sleeve <NUM> from moving in the radial direction, thereby realizing, by the upper flange <NUM>, the position limitation to and the support for an upper end of the piston sleeve <NUM>, preventing the piston sleeve <NUM> from rotating eccentrically and aslant, ensuring the pump body assembly to operate normally, and improving the working reliability of the pump body assembly.

As shown in <FIG>, a step surface <NUM> is disposed on the inner surface of the piston sleeve <NUM>, and the step surface <NUM> is disposed at one end of the piston sleeve <NUM>, and the one end of the piston sleeve <NUM> faces the upper flange <NUM>. The position-limiting part <NUM> extends to the step surface <NUM> to limit and stop the step surface <NUM>, thereby achieving, by the upper flange <NUM>, the position limitation to the piston sleeve <NUM> in the radial direction.

In this embodiment, the position-limiting part <NUM> and the piston sleeve <NUM> are coaxially arranged. Where, the position-limiting part <NUM> and the upper flange <NUM> are eccentrically arranged, and the eccentricity is e. In this case, the eccentricity of the pump body assembly is determined in the above manner, which makes it easier to guarantee the eccentricity of the pump body assembly, and the determination of the eccentricity e is more reliable and simple.

As shown in <FIG>, an eccentric protruding platform is provided on a surface of the lower flange <NUM>, and the surface of the lower flange <NUM> faces the piston sleeve <NUM>. The eccentric protruding platform can limit and stop the lower end of the piston sleeve <NUM> to prevent the lower end of the piston sleeve <NUM> from moving in the radial direction relative to the lower flange <NUM>.

The pump body assembly of the third embodiment differs from that of the second embodiment in that structure of the piston sleeve <NUM> is different.

As shown in <FIG>, a position-limiting part <NUM> is provided on the lower end surface of the upper flange <NUM>, and extends towards the piston sleeve <NUM>. The piston sleeve <NUM> is limited and stopped by the position-limiting part <NUM>, so as to prevent the piston sleeve <NUM> from moving in the radial direction relative to the upper flange <NUM>. Where, the upper end surface of the piston sleeve <NUM> has a first position-limiting groove <NUM>, and the position-limiting part <NUM> extends into the first position-limiting groove <NUM>, so as to limit and stop the first position-limiting groove <NUM>. In this case, the position-limiting part <NUM> of the upper flange <NUM> extends into the first position-limiting groove <NUM> of the piston sleeve <NUM>, and the position-limiting part <NUM> limits and stops the first position-limiting groove <NUM>, thereby achieving, by the upper flange <NUM>, the position limitation to the piston sleeve <NUM> in the radial direction, preventing the piston sleeve <NUM> from moving in the radial direction, realizing, by the upper flange <NUM>, the position limitation to and the support for the upper end of the piston sleeve <NUM>, preventing the piston sleeve <NUM> from rotating eccentrically and aslant, ensuring the pump body assembly to operate normally, and improving the working reliability of the pump body assembly.

As shown in <FIG>, the position-limiting part <NUM>, the first position-limiting groove <NUM>, and the piston sleeve <NUM> are coaxially arranged. Where, the position-limiting part <NUM> and the upper flange <NUM> are eccentrically arranged, and the eccentricity is e. In this case, the eccentricity of the pump body assembly is determined in the above manner, making it easier to guarantee the eccentricity of the pump body assembly, and the determination of the eccentricity e is more reliable and simpler.

The embodiment is not part of the present invention. The pump body assembly of the fourth embodiment differs from that of the first embodiment in that the structure of the lower flange <NUM> is different.

As shown in <FIG>, a position-limiting protrusion <NUM> is provided on a lower end surface of the piston sleeve <NUM>, and the position-limiting protrusion <NUM> fits and limits another structure member located below the cylinder <NUM> thus preventing the piston sleeve <NUM> from moving in the radial direction relative to the other structure member. Where the other structure member located below the cylinder <NUM> is a lower flange <NUM>. In this case, the position-limiting protrusion <NUM> of the piston sleeve <NUM> fits the lower flange <NUM>, so as to limit the position of the piston sleeve <NUM> in the radial direction. At the same time, the upper end of the piston sleeve <NUM> is limited and supported by the upper flange <NUM>, so that both the upper end and the lower end of the piston sleeve <NUM> are limited and supported, thus avoiding structural interference between the piston sleeve <NUM> and the piston <NUM> or cylinder <NUM>, which will affect the normal operation of the pump body assembly, and improving the operation reliability and the working performance of the pump body assembly.

As shown in <FIG>, a second position-limiting groove <NUM> is provided on the surface of the lower flange <NUM>, and the surface of the lower flange <NUM> faces the piston sleeve <NUM>. The position-limiting protrusion <NUM> extends into the second position-limiting groove <NUM> to prevent the piston sleeve <NUM> from moving in the radial direction relative to the lower flange <NUM>. Specifically, the second position-limiting groove <NUM> is eccentrically arranged on the lower flange <NUM>, and the position-limiting protrusion <NUM> extends into the second position-limiting groove <NUM>, thereby realizing, by the lower flange <NUM>, the position limitation and a stop to the piston sleeve <NUM>.

The pump body assembly of the fifth embodiment differs from that of the fourth embodiment in that the structure of the pump body assembly is different.

As shown in <FIG>, the two structure members include the lower flange <NUM> located below the piston assembly; the position-limiting protrusion <NUM> is provided on the surface of the piston sleeve <NUM>, and the surface of the piston sleeve faces the lower flange <NUM>. The pump body assembly further includes a lower friction-reducing ring <NUM> arranged inside the cylinder <NUM>. The lower friction-reducing ring <NUM> has a central hole, and the position-limiting protrusion <NUM> extends into the central hole, and is limited and stopped by the lower flange <NUM>, so as to prevent the piston sleeve <NUM> from moving in the radial direction relative to the lower flange <NUM>. In this case, the central hole of the lower friction-reducing ring <NUM> fits and limits the position-limiting protrusion <NUM> of the piston sleeve <NUM>, and accordingly, the lower friction-reducing ring <NUM> realizes the position limitation to the piston sleeve <NUM> in the radial direction, thereby limiting and stopping the lower end of the piston sleeve <NUM>. At the same time, the upper end of the piston sleeve <NUM> is supported by the upper flange <NUM>, so that both the upper end and the lower end of the piston sleeve <NUM> are limited and supported, thereby avoiding structural interference between the piston sleeve <NUM> and the piston <NUM> or cylinder <NUM>, which will affect the normal operation of the pump body assembly, and improving the working reliability of the pump body assembly.

Specifically, an outer surface of the lower friction-reducing ring <NUM> fits the inner circular surface of the cylinder <NUM>, and an inner surface of the lower friction-reducing ring <NUM> fits the position-limiting protrusion <NUM> of the piston sleeve <NUM>. The lower friction-reducing ring <NUM> rotates relative to the cylinder <NUM> and the position-limiting protrusion <NUM>, and a rotation speed of the lower friction-reducing ring <NUM> relative to the cylinder <NUM> and a rotation speed of the lower friction-reducing ring <NUM> relative to the position-limiting protrusion <NUM> are less than a rotation speed of the rotation shaft <NUM>. As power consumption of the friction pairs is proportional to square of the rotation speed, the power consumption of the pump body assembly is reduced.

In this embodiment, the position-limiting protrusion <NUM> is a protruding ring extending toward the lower flange <NUM>, and the protruding ring and the piston sleeve <NUM> are coaxially arranged. Specifically, in the process of limiting and stopping the protruding ring by the lower flange <NUM>, the protruding ring makes a force exerted on the piston sleeve <NUM> more uniform and stable, thereby making the piston sleeve <NUM> operate more stably, and improving the operation reliability of the pump body assembly.

It should be noted that the structure of the position-limiting protrusion <NUM> is not limited to such.

Optionally, the position-limiting protrusion <NUM> includes a plurality of protruding platforms extending toward the lower flange <NUM>, and the plurality of protruding platforms are arranged at intervals along a circumference of the piston sleeve <NUM>. The above arrangement can not only make quality of the piston sleeve <NUM> reduced, but also make the structure of the piston sleeve <NUM> simpler, thereby reducing processing costs of the piston sleeve <NUM>.

As shown in <FIG>, <FIG> and <FIG>, a second extended part <NUM> is provided on the surface of the lower flange <NUM>, and the surface of the lower flange <NUM> faces the piston sleeve <NUM>. The second extended part <NUM> limits and stops the position-limiting protrusion <NUM>, so as to prevent the piston sleeve <NUM> from moving in the radial direction relative to the lower flange <NUM>. Specifically, a side surface of the second extended part <NUM> fits and limits a side surface of the position-limiting protrusion <NUM>, thereby preventing a relative radial displacement therebetween, further preventing the piston sleeve <NUM> from moving in the radial direction relative to the lower flange <NUM>, ensuring the piston sleeve <NUM> to operate stably, and improving the operation reliability and the working efficiency of the pump body assembly.

Optionally, there is a second predetermined distance between the inner side surface of the second extended part <NUM> and the side surface of the position-limiting protrusion <NUM> away from the center of the piston sleeve <NUM>, and the second predetermined distance is greater than or equal to <NUM>, and less than or equal to <NUM>. In this case, the above numerical range not only ensures that the second extended part <NUM> can limit the position-limiting protrusion <NUM> in the radial direction, but also enables the position-limiting protrusion <NUM> to rotate relative to the second extended part <NUM>, thereby improving the operation reliability of the pump body assembly.

In other embodiments shown in <FIG>, the second extended part <NUM> is located inside the position-limiting protrusion <NUM>. Specifically, an outer side surface of the second extended part <NUM> limits and stops a side surface of the position-limiting protrusion <NUM>, and the side surface of the position-limiting protrusion <NUM> is adjacent to the center of the piston sleeve, thereby preventing a radial displacement therebetween.

The pump body assembly of the sixth embodiment differs from that of the fifth embodiment in that the structure of the lower flange <NUM> is different.

In this embodiment, a second position-limiting groove is provided on the surface of the lower flange, and the surface of the lower flange faces the piston sleeve, and the position-limiting protrusion extends into the second position-limiting groove to prevent the piston sleeve from moving in the radial direction relative to the lower flange. In this case, the position-limiting protrusion not only fits and is limited by the central hole of the lower friction-reducing ring, but also fits the second position-limiting groove of the lower flange, thereby further improving the operation stability of the piston sleeve.

Optionally, the second position-limiting groove is eccentrically arranged on the lower flange, and the eccentricity is e.

According to the present invention, as shown in <FIG>, the structure members further include the lower flange <NUM> and a lower position-limiting plate <NUM>. The lower position-limiting plate <NUM> and the lower flange <NUM> are both disposed below the cylinder <NUM>, and the lower position-limiting plate <NUM> is disposed between the cylinder <NUM> and the lower flange <NUM>. The position-limiting protrusion <NUM> is limited and stopped by the lower position-limiting plate <NUM>, so as to prevent the piston sleeve <NUM> from moving in the radial direction relative to the lower position-limiting plate <NUM>. In this case, the position-limiting protrusion <NUM> of the piston sleeve <NUM> fits and is limited by the lower position-limiting plate <NUM> in the radial direction. At the same time, the upper end of the piston sleeve <NUM> is limited and supported by the upper flange <NUM>, so that both the upper end and the lower end of the piston sleeve <NUM> are limited and supported, thereby avoiding structural interference between the piston sleeve <NUM> and the piston <NUM> or the cylinder <NUM>, which will affect the normal operation of the pump body assembly, and improving the operation reliability and the working performance of the pump body assembly.

As shown in <FIG>, the position-limiting protrusion <NUM> extends into the central hole of the lower position-limiting plate <NUM>, fits and is limited by the inner surface of the central hole of the lower position-limiting plate <NUM>. Specifically, the lower position-limiting plate <NUM> is fixedly connected to the lower flange <NUM>, and the outer surface of the position-limiting protrusion <NUM> is limited and stopped by the inner surface of the central hole, thereby realizing, by the upper flange, the position limitation and the stop to the position-limiting protrusion <NUM> (piston sleeve <NUM>), preventing the piston sleeve <NUM> from moving in the radial direction relative to the lower position-limiting plate <NUM> or the lower flange <NUM>, and further improving the operation reliability of the pump body assembly.

The pump body assembly of the eighth embodiment differs from that of the present invention above in that the structure of the lower position-limiting plate <NUM> is different.

In this embodiment, a surface of the lower position-limiting plate, which faces a surface of the piston sleeve, has a third position-limiting groove, and the position-limiting protrusion extends into the third position-limiting groove, and is limited and stopped by the third position-limiting groove. Specifically, the position-limiting protrusion fits a groove wall of the third position-limiting groove, to realize, by the lower position-limiting plate, the position limitation to the piston sleeve, thereby making the piston sleeve operate more stably, and improving the operation reliability of the pump body assembly.

Optionally, the third position-limiting groove is a ring-shaped groove, and the ring-shaped groove and the central hole of the lower position-limiting plate are arranged coaxially.

From the above description, it can be seen that the above-mentioned embodiments of the present invention achieves the following technical effects:
during the operation of the pump body assembly, the upper end of the piston sleeve is limited and supported by the structure member disposed thereabove, thereby preventing the piston sleeve from moving in the radial direction during operation, ensuring that the piston sleeve can rotate normally, and solving the problem in the prior art that the working efficiency of the pump body assembly is affected because the piston sleeve of the pump body assembly is prone to rotate eccentrically, and improving the operation reliability and the working performance of the pump body assembly.

It should be noted that terms used herein are only for the purpose of describing specific embodiments and not intended to limit the exemplary embodiments of the invention. The singular of a term used herein is intended to include the plural of the term unless the context otherwise specifies. In addition, it should also be appreciated that when terms "include" and/or "comprise" are used in the description, they indicate the presence of features, steps, operations, devices, components and/or their combination.

Claim 1:
A pump body assembly comprising:
at least two structure members,
a cylinder (<NUM>) arranged between the two structure members, and
a piston assembly arranged in the cylinder (<NUM>);
wherein the piston assembly comprises a piston sleeve (<NUM>) and a piston (<NUM>) slidably arranged in the piston sleeve (<NUM>);
a position-limiting protrusion (<NUM>) is provided on a lower end surface of the piston sleeve (<NUM>); the position-limiting protrusion (<NUM>) fits another structure member located below the cylinder (<NUM>) to prevent the piston sleeve (<NUM>) from moving in the radial direction relative to the other structure member,
the at least two structure members comprise a lower flange (<NUM>) and a lower position-limiting plate (<NUM>); the lower position-limiting plate (<NUM>) and the lower flange (<NUM>) are both disposed below the cylinder (<NUM>); the lower position-limiting plate (<NUM>) is disposed between the cylinder (<NUM>) and the lower flange (<NUM>); the position-limiting protrusion (<NUM>) is limited and stopped by the lower position-limiting plate (<NUM>) to prevent the piston sleeve (<NUM>) from moving in the radial direction relative to the lower position-limiting plate (<NUM>);
characterized in that a second extended part (<NUM>) is provided on the surface of the lower flange (<NUM>), and the surface of the lower flange (<NUM>) faces the piston sleeve (<NUM>); the second extended part (<NUM>) limits and stops the position-limiting protrusion (<NUM>) to prevent the piston sleeve (<NUM>) from moving in the radial direction relative to the lower flange (<NUM>);
the second extended part (<NUM>) is located inside the position-limiting protrusion (<NUM>);
the position-limiting protrusion (<NUM>) extends into a central hole of the lower position-limiting plate (<NUM>), fits and is limited by an inner surface of the central hole of the lower position-limiting plate (<NUM>); and
an upper end surface of the piston sleeve (<NUM>) fits and is limited by a lower end surface of one structure member disposed above the piston sleeve (<NUM>) to prevent the piston sleeve (<NUM>) from moving in a radial direction relative to the one structure member.