Patent Publication Number: US-2023160376-A1

Title: Pump body assembly and fluid machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/110103, filed on Aug. 2, 2021, which claims priority to Chinese application No. 202011590433.9, filed on Dec. 29, 2020. All of the aforementioned applications are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a technical field related to rotary cylinder compressors, and specifically to a pump body assembly and a fluid machine. 
     BACKGROUND 
     Taking a rotary cylinder compressor as an example, it is a new type of volumetric compressor. Its cylinder and rotation shaft rotate around their respective centers, and the piston reciprocates with respect to the cylinder and the rotation shaft at the same time. The reciprocating motion of the piston with respect to the cylinder enables periodical enlarging and reducing of the volume cavity; the circular motion with respect to the cylinder sleeve enables communication of the volume cavity with the intake passage and the exhaust passage, respectively. The above two motions cooperate to enable the intake, compression and exhaust processes of the compressor. 
     With the higher and higher requirement of high efficiency and energy saving for compressors, it is necessary to optimize the design of the rotary cylinder compressor to further improve efficiency of the compressor and achieve energy saving and emission reduction. Currently, during running of a rotary cylinder compressor, the rotation shaft divides the sliding hole in the piston into two cavities, and when the rotation shaft of the pump body assembly is sliding with respect to the piston, the two cavities of the sliding hole increase and decrease periodically. and the inner wall of the sliding hole of the piston presses the oil liquid in the sliding hole such that the oil liquid is transferred within the two cavities to achieve the oil pressing process. However, during practical running of a compressor, when the inner wall of the sliding hole of the piston presses the oil liquid, the fluency of the oil liquid will be impeded. During the oil pressing process, the oil liquid causes increase in power consumption of the piston and the rotation shaft, resulting in an increase in power consumption of the pump body assembly of the rotary cylinder compressor. 
     As can be seen from above, currently, there is a problem that the piston impedes a flow of oil liquid during use of rotary cylinder compressors. 
     SUMMARY 
     The main purpose of the present disclosure is to provide a pump body assembly and a fluid machine to solve the problem in prior art that the piston impedes a flow of oil liquid during use of rotary cylinder compressors. 
     In order to achieve the above purpose, according to an aspect of the present disclosure, a pump body assembly is provided, comprising a rotation shaft and a piston provided with a sliding hole, at least a portion of the rotation shaft penetrates into the sliding hole, during rotation of the piston with the rotation shaft, the sliding hole is in sliding fit with the rotation shaft, wherein the piston is provided with a piston communication passage communicated with the sliding hole. 
     In some embodiments, a plurality of the piston communication passages are provided, the plurality of the piston communication passages are disposed on a hole wall face of the sliding hole and/or the plurality of the piston communication passages are disposed on an end face of the piston in an axial direction of the rotation shaft. 
     In some embodiments, the number of the piston communication passages is less than 4. 
     In some embodiments, the sliding hole is provided on its hole wall face with a piston communication groove, and the piston communication groove extends in a sliding direction of the piston and constitutes the piston communication passage. 
     In some embodiments, the piston communication groove has a uniform depth from place to place. 
     In some embodiments, in the sliding direction of the piston, the piston communication groove has a depth H 2  gradually increasing from both ends of the piston communication groove towards a middle portion of the piston communication groove. 
     In some embodiments, the piston communication groove is a groove in a crescent shape. 
     In some embodiments, in an axial direction of the rotation shaft, the piston is provided on its end face with a piston communication groove, and the piston communication groove extends in a sliding direction of the piston and constitutes the piston communication passage. 
     In some embodiments, on the end face of the same end of the piston, a group of two opposite edges of the sliding hole is respectively provided with at least one piston communication groove. 
     In some embodiments, in the axial direction of the rotation shaft, the piston is provided, at each of its top end face and its bottom end face, with the piston communication groove. 
     In some embodiments, with the piston communication groove as a boundary, the end face on a side where the piston communication groove is located comprises a first surface P 1  and a second surface P 2 , wherein the first surface P 1  is in a region between the piston communication groove and an edge of the sliding hole on the side where the piston communication groove is located, and the second surface P 2  is in a region between the piston communication groove and an outer edge of the piston. 
     In some embodiments, a difference in height between the first surface P 1  and the second surface P 2  equals to 0.1 mm. 
     In some embodiments, a distance L 2  between the piston communication groove and an outer edge of the end face of the piston on a side where the piston communication groove is located is greater than or equal to 2 mm. 
     In some embodiments, the sliding hole of the piston is further provided therein with a flexible groove, the flexible groove extends in the axial direction of the rotation shaft, and the flexible groove is communicated at its end with the piston communication groove. 
     In some embodiments, the flexible groove is located at an end of the piston communication groove. 
     In some embodiments, a plurality of the flexible grooves are provided, and both ends of the same piston communication groove are respectively provided with one flexible groove such that a sliding boss protruding from the hole wall face of the sliding hole is formed within the sliding hole. 
     In some embodiments, a surface of the sliding boss facing towards a middle portion of the sliding hole is a sliding face. 
     In some embodiments, the sliding face is a plane. 
     In some embodiments, in the axial direction of the rotation shaft, the flexible groove has its ends penetrating through the end faces on both ends of the piston. 
     In some embodiments, the flexible groove has a length H 3  greater than or equal to 2 mm and less than or equal to 7 mm. 
     In some embodiments, an included angle A between a surface of the flexible groove near a middle portion of the sliding hole and the hole wall face on a side where the flexible groove is located in the sliding hole ranges from 10° to 30°. 
     In some embodiments, the flexible groove comprises a first groove surface and a second groove surface, which are connected in sequence, in a direction close to a middle portion of the sliding hole; a first transition fillet □ 1  is formed between the first groove surface and the hole wall face of the sliding hole, a second transition fillet □ 2  is formed between the second groove surface and the first groove surface, and a third transition fillet □ 3  is formed at an edge on a side of the second groove surface far away from first groove surface. 
     In some embodiments, the first transition fillet □ 1  is 0.3°-1°, and/or the second transition fillet □ 2  is 0.3°-1°, and/or the third transition fillet □ 3  is 0.5°-3°. 
     In some embodiments, the piston communication groove has a width H 1  accounting for 1%-12% of a width W 1  of the piston. 
     In some embodiments, the piston communication groove has a depth H 2  accounting for 3%-50% of a width W 1  of the piston. 
     In some embodiments, the pump body assembly further comprises a cylinder sleeve and a cylinder, wherein the cylinder is rotatably arranged in the cylinder sleeve and is provided thereon, in its radial direction, with a piston hole, the piston is slidably arranged in the piston hole, the rotation shaft penetrates through the piston and drives the piston to reciprocate in an extension direction of the piston hole, and the cylinder rotates to cause rotation of the piston. 
     According to another aspect of the present disclosure, a fluid machine is provided, comprising the pump body assembly. 
     With the technical solutions of the present disclosure, the pump body assembly comprises a rotation shaft and a piston provided with a sliding hole, with at least a portion of the rotation shaft penetrating into the sliding hole, during rotation of the piston with the rotation shaft, the sliding hole is in sliding fit with the rotation shaft, wherein the piston is provided with a piston communication passage communicated with the sliding hole. 
     As can be seen from the above description, in the above embodiment(s) of the present disclosure, by setting the piston communication passage in the sliding hole of the piston, the fluency of oil liquid flow is increased and the power consumption of the pump body assembly is reduced. Currently, during running of a rotary cylinder compressor, when the rotation shaft of the pump body assembly is sliding with respect to the piston, an inner wall of the sliding hole of the piston will impede fluency of oil liquid flow when pressing the oil liquid and cause increase in power consumption of the pump body assembly. 
     Specifically, the rotation shaft penetrates through the sliding hole on the piston and divides the portion inside the piston into two cavities. During movement of the pump body assembly, the piston reciprocates with respect to the rotation shaft, and the two cavities increase and decrease periodically to achieve the oil pressing process. During the reciprocating movement of the piston, the inner wall of the sliding hole of the piston will press the oil liquid to enable transfer of the oil liquid between the two cavities. The piston communication passage communicated with the sliding hole is disposed on the piston so as to improve fluency of oil liquid transfer, to decrease resistance to pressing oil liquid by the piston, to reduce power consumption of the rotation shaft and the piston during the oil pressing process, and to reduce power consumption of the pump body assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings for the description, which constitutes a portion of the present application, are used to provide further understanding to the present disclosure. The illustrative embodiments of the present disclosure and the description thereof are used to explain the present disclosure, rather than forming inappropriate limitation to the present disclosure. In the drawings/figures: 
         FIG.  1    shows an exploded view of a pump body assembly in the present disclosure. 
         FIG.  2    shows a diagram for mounting relation of a rotation shaft and a piston in  FIG.  1   . 
         FIG.  3    shows a diagram of a piston communication groove disposed on a hole wall face of a sliding hole of the piston in the present disclosure wherein the piston communication groove is a rectangular groove. 
         FIG.  4    shows a diagram of a piston communication groove disposed on a hole wall face of a sliding hole of the piston in the present disclosure wherein the piston communication groove is a groove in a crescent shape. 
         FIG.  5    shows a diagram of a piston communication groove disposed on an end face of the piston in the present disclosure. 
         FIG.  6    shows a top view of  FIG.  5   . 
         FIG.  7    shows a side view of  FIG.  5   . 
         FIG.  8    shows an axial section view of  FIG.  7   . 
         FIG.  9    shows a diagram of a piston communication groove and a flexible groove disposed on an end face of the piston in the present disclosure. 
         FIG.  10    shows a top view of  FIG.  9   . 
         FIG.  11    shows a diagram for mounting relation of various components in the pump body assembly in the present disclosure. 
         FIG.  12    shows a section view along A-A in  FIG.  11   . 
         FIG.  13    shows a diagram of an avoidance recess provided on a cylinder in the present disclosure. 
         FIG.  14    shows a top view of  FIG.  13   . 
         FIG.  15    shows an enlarged view of a in  FIG.  14   . 
         FIG.  16    shows a diagram of a rotation shaft communication groove provided in the rotation shaft in the present disclosure. 
         FIG.  17    shows an enlarged view at b in  FIG.  16   . 
         FIG.  18    shows a diagram of a rotation shaft flow-through hole provided in the rotation shaft in the present disclosure. 
         FIG.  19    shows a diagram of a shaft segment of the rotation shaft within a sliding hole in the present disclosure. 
         FIG.  20    shows a diagram of mounting relation of the rotation shaft with a cylinder and a lower flange in the present disclosure. 
         FIG.  21    shows a diagram of mounting relation of the rotation shaft and the piston in the present disclosure. 
         FIG.  22    shows a top view of  FIG.  21   . 
         FIG.  23    shows a structural diagram of an avoidance recess provided in a lower flange in the present disclosure wherein the avoidance recess is in a crescent shape and the crescent shape has an outer circle which is concentric with the lower flange. 
         FIG.  24    shows a section view of the avoidance recess in  FIG.  23   . 
         FIG.  25    shows a structural section view of the lower flange in  FIG.  23   . 
         FIG.  26    shows an axial section view of the rotation shaft, a cylinder, a lower flange and the piston in a direction perpendicular to movement of the piston. 
         FIG.  27    shows an axial section view of the rotation shaft, a cylinder, a lower flange and the piston in a direction of movement of the piston. 
         FIG.  28    shows a structural diagram of an avoidance recess provided in a lower flange in the present disclosure wherein the avoidance recess is in an irregular shape. 
         FIG.  29    shows a structural diagram of an avoidance recess provided in a lower flange in the present disclosure, wherein the avoidance recess is in a crescent shape and the crescent shape has an outer circle which is not concentric with the lower flange. 
     
    
    
     DETAILED DESCRIPTIONS OF THE EMBODIMENTS 
     It should be noted that the embodiments in the present application and the features therein can be combined with one another if there is no contradiction. Hereinafter, the present disclosure will be explained in detail with reference to the accompanying drawings and in combination with the embodiments. 
     It should be pointed out that any technical or scientific term used in the present application has the same meaning as generally understood by those skilled in the art of the present application, unless otherwise specified. 
     In the present disclosure, the used direction-position expressions, such as “above”, “below”, “top”, “bottom”, are generally used with respect to the direction(s) as shown in the figures, or with respect to the vertical, perpendicular or gravity direction for a part per se, unless specified on the contrary. Similarly, in order to facilitate understanding and description, the expressions of “inner” and “outer” refer to inner and outer portions of contours of parts per se. However, the above direction-position expressions are not used to limit the present disclosure. 
     In order to solve the problem in prior art that oil liquid flow is impeded during use of rotary cylinder compressors due to structures of a cylinder  10 , a piston  20 , a rotation shaft  30  and a flange, a pump body assembly and a fluid machine are provided in the present application. 
     Herein, the fluid machine comprises the pump body assembly as described below. Specifically, the fluid machine is a compressor. In some embodiments, the compressor is a rotary cylinder compressor. 
     In order to solve the problem in prior art of impediment to oil liquid flow during use of rotary cylinder compressors, it is possible to optimize the piston  20  so as to reduce impediment of the piston  20  to the oil liquid, thereby reducing power consumption of the pump body assembly. 
     Specifically, as shown in  FIGS.  1 - 10   , a pump body assembly comprises a rotation shaft  30  and a piston  20  provided with a sliding hole  2011 , at least a portion of the rotation shaft  30  penetrates into the sliding hole  2011 , wherein during rotation of the piston  20  with the rotation shaft  30 , the sliding hole  2011  is in sliding fit with the rotation shaft  30 . The piston  20  is provided with a piston communication passage communicated with the sliding hole  2011 . 
     As can be seen from the above description, in the above embodiment of the present disclosure, a piston communication passage is provided inside the sliding hole  2011  of the piston  20  so as to improve fluency of oil liquid flow and reduce power consumption of the pump body assembly. Currently, during running of a rotary cylinder compressor, when the rotation shaft  30  of the pump body assembly is sliding with respect to the piston  20 , an inner wall of the sliding hole  2011  of the piston  20  will impede fluency of oil liquid flow when pressing the oil liquid and cause increase in power consumption of the pump body assembly. 
     Specifically, the rotation shaft  30  penetrates into the sliding hole  2011  on the piston  20  and divides the portion inside the piston  20  into two cavities. During movement of the pump body assembly, the piston  20  reciprocates with respect to the rotation shaft  30 , and the two cavities increase and decrease periodically to achieve the oil pressing process. During the reciprocating movement of the piston  20 , the inner wall of the sliding hole  2011  of the piston  20  will press the oil liquid to enable transfer of the oil liquid between the two cavities. The piston communication passage communicated with the sliding hole  2011  is disposed on the piston  20  so as to improve fluency of oil liquid transfer, to decrease resistance to pressing oil liquid by the piston  20 , to reduce power consumption of the rotation shaft  30  and the piston  20  during the oil pressing process, and to reduce power consumption of the pump body assembly. 
     In some embodiments, the number of the piston communication passages is less than 4. If the number of the piston communication passages is more than 4, the strength of the piston  20  will be affected, which will lead to insufficient stability of the piston  20  and decreased oil pressing power, and thus affect the whole running efficiency of the pump body assembly. 
     It should be noted that in the specific embodiments as shown in  FIGS.  3 - 10   , there are various implementations according to the difference(s) in the position(s) provided for the piston communication passage(s) and the shape(s) of the piston communication passage(s) as long as the impediment to oil liquid during the oil pressing process due to the piston  20  can be reduced, and they will not be described herein one by one. 
     Hereinafter, according to different structures for the piston communication passages disposed on the piston  20 , various implementations in  FIGS.  3 - 10    are provided. 
     In a specific implementation as shown in  FIG.  3   , a piston communication passage is disposed on a hole wall face of the sliding hole  2011 . The piston communication passage is a rectangular piston communication groove  2021  having a uniform depth from place to place. 
     Specifically, by setting a rectangular piston communication groove  2021  on the hole wall face of the sliding hole  2011  of the piston  20 , the piston communication groove  2021  extends in the sliding direction of the piston  20  and constitutes the piston communication passage, thus enlarging the flow path of the oil liquid. When the hole wall face of the sliding hole  2011  of the piston  20  presses the oil liquid, the oil liquid can be transferred via the piston communication groove  2021 , improving fluency of oil liquid transfer and also reducing power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process. 
     In a specific implementation as shown in  FIG.  4   , a piston communication passage is disposed on a hole wall face of the sliding hole  2011 . The piston communication passage is a piston communication grooves  2021  in a crescent shape. 
     It should be noted that in the sliding direction of the piston  20 , the piston communication groove  2021  has a depth H 2  gradually increasing from both ends of the piston communication groove  2021  towards a middle portion of the piston communication groove  2021 , thus forming the piston communication groove  2021  in a crescent shape. 
     Specifically, by setting a piston communication groove  2021  in a crescent shape on the hole wall face of the sliding hole  2011  of the piston  20 , the piston communication groove  2021  extends in the sliding direction of the piston  20  and constitutes the piston communication passage, thus enlarging the flow path of the oil liquid. When the hole wall face of the sliding hole  2011  of the piston  20  presses the oil liquid, the oil liquid can be transferred via the piston communication groove  2021 , improving fluency of oil liquid transfer and also reducing power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process. 
     In specific implementations as shown in  FIGS.  5 - 8   , a plurality of the piston communication passages are provided, the plurality of the piston communication passages are disposed on an end face of the piston  20  in an axial direction of the rotation shaft  30 . The piston communication passage is the piston communication groove  2021 . 
     In some embodiments, the piston communication groove  2021  extends in a sliding direction of the piston  20  and constitutes the piston communication passage. 
     Specifically, by setting the piston communication passage on an end face of the piston  20  in an axial direction of the rotation shaft  30 , the flow path of the oil liquid is enlarged. When the hole wall face of the sliding hole  2011  of the piston  20  presses the oil liquid, the oil liquid can be transferred via the piston communication groove  2021 , improving fluency of oil liquid transfer and also reducing power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process. 
     As shown in  FIGS.  5 - 8   , on the end face of the same end of the piston  20 , a group of two opposite edges of the sliding hole  2011  is respectively provided with at least one piston communication groove  2021 . By setting the piston communication groove  2021  at the two edges in opposite positions of the sliding hole  2011 , when the piston  20  presses the oil liquid, the oil liquid can be transferred via the piston communication groove  2021 , improving movement fluency of oil liquid and reducing power consumption of the pump body assembly. 
     As shown in  FIGS.  5 - 8   , in the axial direction of the rotation shaft  30 , the piston  20  is provided, at each of its top end face and its bottom end face, with the piston communication groove  2021 . The piston communication groove  2021  is disposed at each of the top end face and the bottom end face of the piston  20 , to enlarge the flow path of the oil liquid. When the inner wall of the sliding hole  2011  of the piston  20  presses the oil liquid, the movement fluency of oil liquid is improved and the power consumption of the pump body assembly is reduced. 
     As shown in  FIG.  7   , with the piston communication groove  2021  as a boundary, the end face on a side where the piston communication groove  2021  is located comprises a first surface P 1  and a second surface P 2 , wherein the first surface P 1  is in a region between the piston communication groove  2021  and an edge of the sliding hole  2011  on a side where the piston communication groove  2021  is located, and the second surface P 2  is in a region between the piston communication groove  2021  and an outer edge of the piston  20 . Thus, during movement of the piston  20 , the second surface P 2  will not contact the cylinder, thereby preventing friction. 
     Specifically, a difference in height between the first surface P 1  and the second surface P 2  is 0.1 mm. When the difference in height is greater than 0.1 mm, it is possible to affect the strength of the piston  20  due to the difference in height being too large. When difference in height is less than 0.1 mm, the flowability of oil liquid cannot be effectively improved and the power consumption of the pump body assembly during the oil pressing process cannot be reduced. 
     As shown in  FIG.  6   , a distance L 2  between the piston communication groove  2021  and an outer edge of the end face of the piston  20  on a side where the piston communication groove  2021  is located is greater than or equal to 2 mm. When the distance between the piston communication groove  2021  and an outer edge of the end face of the piston  20  on a side where the piston communication groove  2021  is located is less than 2 mm, the strength of the piston  20  will be affected due to the wall thickness of the piston  20  being too small, the piston  20  is prone to be damaged during running such that the pump body assembly cannot operate normally. 
     In specific implementations as shown in  FIGS.  9 - 10   , a plurality of the piston communication passages are provided, the plurality of the piston communication passages are disposed on an end face of the piston  20  in an axial direction of the rotation shaft  30 . The piston communication passage is a combined structure of the piston communication groove  2021  and the flexible groove  2023 , wherein the flexible groove  2023  is disposed within the sliding hole  2011  of the piston  20  and is located at an end of the piston communication groove  2021 . 
     In some embodiments, the flexible groove  2023  extends in the axial direction of the rotation shaft  30 , and the flexible groove  2023  is communicated at its end with the piston communication groove  2021 . 
     Specifically, by setting the piston communication groove  2021  and the flexible groove  2023  in the sliding hole  2011  of the piston  20 , the flow path of the oil liquid is enlarged. When the sliding hole  2011  of the piston  20  presses the oil liquid, the fluency of oil liquid transfer can be improved to reduce impediment of oil liquid to the piston  20  and the rotation shaft  30 , and the power consumption of the pump body assembly is reduced. 
     As shown in  FIGS.  9 - 10   , a plurality of the flexible grooves  2023  are provided, and both ends of the same piston communication groove  2021  are respectively provided with one flexible grooves  2023 , wherein in the axial direction of the rotation shaft  30 , the ends of the flexible groove  2023  go through the end faces on both ends of the piston  20 , such that a sliding boss  2022  protruding from the hole wall face of the sliding hole  2011  is formed within the sliding hole  2011 . 
     Specifically, a surface of the sliding boss  2022  facing towards a middle portion of the sliding hole  2011  is a sliding face  2024 . The sliding face  2024  is a plane. During running of the pump body assembly, the sliding face  2024  and the rotation shaft  30  are in sliding fit with each other to achieve the oil pressing process. By cooperation of the piston communication groove  2021  and the flexible groove  2023 , the fluency of oil liquid transfer is improved, the impediment of oil liquid to the piston  20  and the rotation shaft  30  is reduced, and the power consumption of the pump body assembly is reduced. 
     As shown in  FIG.  10   , the flexible groove  2023  has a length H 3  greater than or equal to 2 mm and less than or equal to 7 mm. When the length H 3  of the flexible groove  2023  is less than 2 mm, the flexible groove  2023  is too small and thus is not conducive to improve the fluency of oil liquid. When the length H 3  of the flexible groove  2023  is greater than 7 mm, the strength of the sliding boss  2022  is affected and the sliding boss  2022  is prone to be damaged during sliding fit with the rotation shaft  30 . 
     As shown in  FIG.  10   , an included angle A between a surface of the flexible groove  2023  near a middle portion of the sliding hole  2011  and the hole wall face on a side where the flexible groove  2023  is located in the sliding hole  2011  ranges from 10° to 30°. If the included angle A is too large, the strength of the portion where the flexible groove  2023  on the sliding boss  2022  is located will be affected, and the sliding boss  2022  is prone to be damaged during sliding fit with the rotation shaft  30 . If the included angle A is too small, it can&#39;t improve the fluency of oil liquid transfer, reduce impediment of oil liquid to the piston  20  and the rotation shaft  30 , and reduce power consumption of the pump body assembly. 
     As shown in  FIG.  10   , the flexible groove  2023  comprises a first groove surface and a second groove surface which are connected in sequence in a direction close to a middle portion of the sliding hole  2011 , a first transition fillet □ 1  is formed between the first groove surface and the hole wall face of the sliding hole  2011 , a second transition fillet □ 2  is formed between the second groove surface and the first groove surface, and a third transition fillet □ 3  is formed at an edge on a side of the second groove surface far away from first groove surface. 
     Specifically, the first transition fillet □ 1  is 0.3°-1°, the second transition fillet □ 2  is 0.3°-1°, and the third transition fillet □ 3  is 0.5°-3°. By setting the fillet and the corresponding angle ranges, the flowability of oil liquid is improved and the power consumption of the pump body assembly is reduced, without affecting the strength of the sliding boss  2022 . The disposed fillet facilitates reducing the concentrated stress on the sliding boss  2022  and enables stable running during the oil pressing process. 
     It should be noted that the piston  20  may also be formed by  3 D printing technology, with a large hollow inside as machined and an outer housing, which cannot be formed by general machining. The inner wall of the sliding hole  2011  is provided with a piston communication groove  2021  in an irregular shape. The piston communication groove  2021  has a first width equal to 12%-70% of a width W 1  of the piston  20 , the piston communication groove  2021  has a second width equal to 1%-12% of a width W 1  of the piston  20 , and the piston communication groove  2021  has a wall thickness of 2 mm-4 mm. 
     As shown in  FIG.  6   , the piston communication groove  2021  has a width H 1  accounting for 1%-12% of a width W 1  of the piston  20 . Specifically, when the width H 1  of the piston communication groove  2021  is too small, the fluency of oil liquid transfer during the oil pressing process cannot be effectively improved and the effect of reduction in power consumption of the pump body assembly cannot be achieved. When the width H 1  of the piston communication groove  2021  is too large, the strength of the rotation shaft  30  will be affected, and the rotation shaft  30  is prone to break during its movement with respect to the piston  20 . 
     As shown in  FIGS.  3 ,  5 ,  6   , the piston communication groove  2021  has a depth H 2  accounting for 3%-50% of a width W 1  of the piston  20 . Specifically, when the depth H 2  of the piston communication groove  2021  is too small, the fluency of oil liquid transfer during the oil pressing process cannot be effectively improved and the effect of reduction in power consumption of the pump body assembly cannot be achieved. When the depth H 2  of the piston communication groove  2021  is too large, the strength of the rotation shaft  30  will be affected, and the rotation shaft  30  is prone to break during its movement with respect to the piston  20 . 
     The pump body assembly in the present disclosure further comprises a cylinder sleeve  40  and a cylinder  10 , wherein the cylinder  10  is rotatably arranged in the cylinder sleeve  40  and the cylinder  10  is provided, in its radial direction, with a piston hole  106 , the piston  20  is slidably arranged in the piston hole  106 , the rotation shaft  30  penetrates through the piston  20  and drives the piston  20  to reciprocate in an extension direction of the piston hole  106 , and the cylinder  10  rotates to cause rotation of the piston  20 . 
     Specifically, in the process that the rotation shaft  30  drives the piston  20  to reciprocate in an extension direction of the piston hole  106 , the piston  20  presses the oil liquid to achieve the oil pressing process of the pump body assembly. The oil liquid is transferred within two cavities formed by the rotation shaft  30  with the piston  20  and the cylinder  10 . By setting the piston communication passage on the piston  20 , the impediment of the piston to oil liquid transfer during oil liquid flowing is reduced, thus reducing power consumption of the pump body assembly during the oil pressing process. 
     As can be seen from the above description, the above embodiment(s) of the present disclosure can achieve the following technical effect(s): 
     By setting the piston communication passage(s) in the sliding hole  2011  of the piston  20 , the fluency of oil liquid flow is improved and the power consumption of the pump body assembly is reduced. Currently, during running of a rotary cylinder compressor, when the rotation shaft  30  of the pump body assembly is sliding with respect to the piston  20 , an inner wall of the sliding hole  2011  of the piston  20  will impede fluency of oil liquid flow when pressing the oil liquid and cause increase in power consumption of the pump body assembly. 
     Specifically, the rotation shaft  30  penetrates through the sliding hole  2011  on the piston  20  and divides the portion inside the piston  20  into two cavities. During movement of the pump body assembly, the piston  20  reciprocates with respect to the rotation shaft  30 , and the two cavities increase and decrease periodically to achieve the oil pressing process. During the reciprocating movement of the piston  20 , the inner wall of the sliding hole  2011  of the piston  20  will press the oil liquid to enable transfer of the oil liquid between the two cavities. The communication passage communicated with the sliding hole  2011  is disposed on the piston  20  so as to improve fluency of oil liquid transfer, to decrease resistance to pressing oil liquid by the piston  20 , to reduce power consumption of the rotation shaft  30  and the piston  20  during the oil pressing process, and to reduce power consumption of the pump body assembly. 
     In order to solve the problem in prior art of impediment of the piston to oil liquid flow during use of rotary cylinder compressors, the cylinder  10  may be optimized, decreasing a gap between a stop convex ring  1011  on the cylinder  10  and the rotation shaft  30  to reduce impediment of the stop convex ring  1011  of the cylinder  10  to oil liquid and thus reduce power consumption of the pump body assembly. 
     Specifically, as shown in  FIGS.  11 - 15   , the pump body assembly comprises a cylinder  10  and a rotation shaft  30 , the cylinder  10  is rotatably arranged and the cylinder  10  is provided, in its axial direction, with a stop convex ring  1011 ; the rotation shaft  30  penetrates through the stop convex ring  1011  and extends into the cylinder  10 , the stop convex ring  1011  is provided, on an inner annular plane on a side facing towards the rotation shaft  30 , with an avoidance recess  1012  such that a flow-through gap is formed between the rotation shaft  30  and the avoidance recess  1012 . 
     As can be seen from the above description, in the above embodiment(s) of the present disclosure, by setting the avoidance recess  1012  on the stop convex ring  1011  of the cylinder  10  on the inner annular plane on the side facing towards the rotation shaft  30 , the flow-through gap between the rotation shaft  30  and the cylinder  10  is increased and the oil liquid resistance to the rotation shaft  30  and the piston  20  is reduced, thus improving running stability. Currently, in the prior pump body assembly, the flow-through gap formed between the rotation shaft  30  and the inner wall of the stop convex ring  1011  on the cylinder  10  is too small, the piston  20  and the rotation shaft  30  are impeded by the oil liquid during movement, resulting in increased power consumption for oil pressing of the piston  20  and the rotation shaft  30  and also affecting stability of the rotation shaft  30  and the piston  20 . 
     Specifically, the rotation shaft  30  penetrates through the cylinder  10  and the flow-through gap is formed between the rotation shaft  30  and the inner annular plane of the stop convex ring  1011  of the cylinder  10 . The avoidance recess  1012  is disposed on the inner annular plane of the stop convex ring  1011  to increase the flow-through gap between the rotation shaft  30  and the cylinder  10  to facilitate flow and transfer of oil liquid, effectively reducing oil liquid resistance to the rotation shaft  30  and the piston  20  during rotation, and preventing the rotation shaft  30  and the piston  20  from increase of power consumption or being unstable due to impediment of oil liquid to the rotation shaft  30  and the piston  20 . 
     As shown in  FIGS.  12 - 15   , the avoidance recess  1012  extends to edges on both sides of the stop convex ring  1011  in the axial direction of the rotation shaft  30 . 
     Specifically, the avoidance recess  1012  extends to the edges on both sides of the stop convex ring  1011  to form a gap passage, enlarging the flow-through gap, improving fluency of the oil liquid flowing through the flow-through gap, reducing impediment of oil liquid to the rotation shaft  30 , and reducing power consumption of the pump body assembly. 
     As shown in  FIGS.  12 - 15   , the avoidance recess  1012  is an avoidance groove disposed on an inner annular face such that the wall thickness of the portion of the stop convex ring  1011  with the hiding groove is less than that of the portion of the stop convex ring  1011  without the hiding groove. 
     Specifically, the avoidance recess  1012  is a hiding groove disposed on an inner annular face. The hiding groove is provided to increase the flow-through gap at the hiding groove. During the oil pressing process of the pump body assembly, when the oil liquid is pressed to flow through the hiding groove, the impediment to the oil liquid can be reduced, improving fluency of oil liquid flow and reducing power consumption of the pump body assembly. 
     In the present disclosure, the flow-through gap is greater than 1 mm and less than 3 mm. The flow-through gap controlled to be within the range from 1 mm to 3 mm can effectively improve fluency of oil liquid flow and reduce power consumption of the pump body assembly. When the flow-through gap is less than 1 mm, it is too small to improve fluency of oil liquid flowing through the flow-through gap and cannot achieve the effect of reduction in power consumption of the pump body assembly. When the flow-through gap is greater than 3 mm, it is too large and will affect the strength of the portion at the stop convex ring  1011  of the cylinder  10 , and thus the stop convex ring  1011  is prone to be damaged, resulting in that the problems of inclination and oil leakage are prone to occur to the cylinder  10  during running. 
     Specifically, the avoidance recess  1012  has a width in a circumferential direction of the inner annular face which equals to 2%-5% of a diameter of the inner annual face. When the width of avoidance recess  1012  in the circumferential direction of the inner annular face is too small, the width of the flow-through gap formed at the avoidance recess  1012  is too small, the fluency of the oil liquid flowing through the flow-through gap cannot be effectively improved, and the effect of reduction in power consumption of the pump body assembly cannot be achieved. When the width of avoidance recess  1012  in the circumferential direction of the inner annular face is too large, the stability of the stop convex ring  1011  of the cylinder  10  will be affected, resulting in that the problems of inclination and oil leakage are prone to occur to the cylinder  10  during running, and also affecting stable running of the pump body assembly. 
     It should be noted that the width of the avoidance recess  1012  in the circumferential direction of the inner annular face may be changed according to the size of the stop convex ring  1011  on the cylinder  10 . For different types of cylinders  10 , the corresponding avoidance recesses  1012  having different widths may be provided on the inner annular face of the stop convex ring  1011  of the cylinder  10 . 
     As shown in  FIGS.  14 - 15   , the flow-through gap is 2%-30% of the diameter of the inner annular face. Specifically, when the pump body assembly is pressing oil, the oil liquid can flow through the flow-through gap to reduce impediment of the stop convex ring  1011  to the oil liquid, thus improving fluency of oil liquid flow and reducing power consumption during the oil pressing process of the pump body. When the flow-through gap is too small, it is too small to improve fluency of the oil liquid flowing through the flow-through gap and cannot achieve the effect of reduction in power consumption of the pump body assembly. When the flow-through gap is too large, it will affect the strength of the portion at the stop convex ring  1011  of the cylinder  10 , and thus the stop convex ring  1011  is prone to be damaged, resulting in that the problems of inclination and oil leakage are prone to occur to the cylinder  10  during running, and also affecting stable running of the pump body assembly. 
     It should be noted that the flow-through gap may be varied according to the size of the stop convex ring  1011  on the cylinder  10 . For different types of cylinders  10 , the corresponding flow-through gaps may be provided on the inner annular face of the stop convex ring  1011  of the cylinder  10 . 
     As shown in  FIG.  15   , the stop convex ring  1011  has a minimum wall thickness t greater than or equal to 1 mm at the portion where the avoidance recess  1012  is located. With the stop convex ring  1011  having the wall thickness greater than or equal to 1 mm, during rotation of the cylinder  10 , the stop convex ring  1011  has a function of positioning. The stop convex ring  1011  has an influence on the stability of the cylinder  10  and prevents the cylinder  10  from inclination. The stop convex ring  1011  is robust. Therefore, the stop convex ring  1011  has a minimum wall thickness t greater than or equal to 1 mm to ensure strength of the stop convex ring  1011  such that the cylinder  10  can run stably. 
     As shown in  FIGS.  11 ,  13 ,  14 ,  15   , the cylinder  10  is provided thereon, in its radial direction, with a piston hole  106 . The inner annular face of the stop convex ring  1011  has a first face segment  1013  and a second face segment  1014  opposite thereto. A connection line of the first face segment  1013  and the second face segment  1014  is perpendicular to an extension direction of the piston hole  106 . Each of the first face segment  1013  and the second face segment  1014  is provided with the avoidance recess  1012 . 
     Specifically, the connection line of the first face segment  1013  and the second face segment  1014  of the stop convex ring  1011  of the cylinder  10  is perpendicular to the extension direction of the piston hole  106  on the cylinder  10 . The oil liquid flows through the first face segment and the second face segment. Each of the first face segment  1013  and the second face segment  1014  is provided thereon with the avoidance recess  1012 . It can improve fluency of oil liquid at the flow-through gap, facilitate oil liquid transfer, and thus reduce power consumption of the pump body assembly. 
     It should be noted that during mounting of the pump body assembly, the rotation shaft  30  may be close to the first face segment or to the second face segment. Each of the first face segment and the second face segment is provided thereon with the avoidance recess  1012 . Therefore, when the rotation shaft  30  is close to either the first face segment or the second face segment, the same technical effect can be achieved, both improving fluency of oil liquid and facilitating mounting. 
     As shown in  FIGS.  11 - 15   , the pump body assembly further comprises a piston  20  provided with a sliding hole  2011 , the rotation shaft  30  penetrates through the sliding hole  2011 , and a group of face segments of the inner annular face of the stop convex ring  1011  in the extension direction of the sliding hole  2011  are each provided with the avoidance recess  1012 . 
     Specifically, the piston  20  is provided thereon with a sliding hole  2011 . The piston  20  moves within the cylinder  10  to achieve oil pressing. The piston  20  presses the oil liquid to enable oil liquid transfer. The oil liquid pressed by the piston  20  will flow through a group of face segments of the stop convex ring  1011  in the extension direction of the sliding hole  2011 . The face segments is provided thereon with the avoidance recess  1012 . It can reduce oil pressing resistance to the piston  20 , reduce vibration of the piston  20 , and avoid the problem of damage to the piston  20 . Also, the avoidance recess  1012  improves fluency of oil liquid flow, reduces resistance between the rotation shaft  30  and the oil liquid, and reduces power consumption of the pump body assembly. Herein, just another reference is used. The extension direction of the piston hole  106  is previously used as reference, while the extension direction of the sliding hole  2011  is herein used as reference, wherein the extension direction of the piston hole  106  may be same as or perpendicular to the extension direction of the sliding hole  2011 . Specifically, it is apparent in  FIG.  12    that the extension direction of the piston hole  106  is perpendicular to that of the sliding hole  2011 . 
     As shown in  FIG.  11   , the pump body assembly further comprises a cylinder sleeve  40  having a volume cavity  4001 . The cylinder  10  is rotatably arranged in the volume cavity  4001 . The piston  20  is slidably arranged in the piston hole  106  of the cylinder  10 . The rotation shaft  30  penetrates through the sliding hole  2011  of the piston  20  and drives the piston  20  to reciprocate in an extension direction of the piston hole  106 . The cylinder  10  rotates to cause rotation of the piston  20 . 
     Specifically, the cylinder  10  and the rotation shaft  30  rotate. The cylinder  10  can cause the piston  20  to rotate. The rotation shaft  30  penetrates through the sliding hole  2011  of the piston  20  and divides a volume cavity  4001  inside the cylinder  10  and the piston  20  into two cavities. With the action of the rotation shaft  30 , the piston  20  reciprocates within the piston hole  106  in the extension direction of the piston hole  106 . The reciprocating movement of the piston  20  causes the two cavities to increase and decrease periodically. Also, the piston  20  presses the oil liquid within the cylinder  10  to achieve periodical transfer of the oil liquid within the two cavities. By setting the avoidance recess  1012  on the inner annular face of the stop convex ring  1011  of the cylinder  10 , the impediment of the stop convex ring  1011  to the oil liquid during transfer of the oil liquid can be reduced, improving fluency of oil liquid transfer and reducing power consumption of the pump body assembly. 
     As can be seen from the above description, the above embodiment(s) of the present disclosure can achieve the following technical effect(s): 
     By setting the avoidance recess  1012  on the stop convex ring  1011  of the cylinder  10  on the inner annular plane on the side facing towards the rotation shaft  30 , the flow-through gap between the rotation shaft  30  and the cylinder  10  is increased and the oil liquid resistance to the rotation shaft  30  and the piston  20  is reduced, thus improving running stability. Currently, in the prior pump body assembly, the flow-through gap formed between the rotation shaft  30  and the inner wall of the stop convex ring  1011  on the cylinder  10  is too small, the piston  20  and the rotation shaft  30  are impeded by the oil liquid during movement, resulting in increased power consumption for oil pressing of the piston  20  and the rotation shaft  30  and also affecting stability of the rotation shaft  30  and the piston  20 . 
     Specifically, the rotation shaft  30  penetrates through the cylinder  10  and the flow-through gap is formed between the rotation shaft  30  and the inner annular plane of the stop convex ring  1011  of the cylinder  10 . The avoidance recess  1012  is disposed on the inner annular plane of the stop convex ring  1011  to increase the flow-through gap between the rotation shaft  30  and the cylinder  10  to facilitate flow and transfer of oil liquid, it can effectively reduce oil liquid resistance to the rotation shaft  30  and the piston  20  during rotation, and prevent the rotation shaft  30  and the piston  20  from producing increased power consumption or being unstable due to impediment of oil liquid to the rotation shaft  30  and the piston  20 . 
     In order to solve the problem in prior art of impediment to oil liquid flow during use of rotary cylinder compressors, it is possible to optimize the rotation shaft  30  so as to reduce impediment of the rotation shaft  30  to the fluency of oil liquid flow in the piston  20 , thereby reducing power consumption of the pump body assembly. 
     Specifically, as shown in  FIGS.  16 - 19   , a pump body assembly comprises a rotation shaft  30  and a piston  20  provided with a sliding hole  2011 , with at least a portion of the rotation shaft  30  penetrating into the sliding hole  2011 , during rotation of the piston  20  with the rotation shaft  30 , the sliding hole  2011  is in sliding fit with the rotation shaft  30 , wherein the rotation shaft  30  is provided, on the shaft segment of the rotation shaft  30  in the sliding hole  2011 , with a rotation shaft flow-through passage, and the rotation shaft flow-through passage extends in the sliding direction of the piston  20 . 
     As can be seen from the above description, in the above embodiment(s) of the present disclosure, the rotation shaft  30  is provided, on the shaft segment of the rotation shaft  30  in the sliding hole  2011  of the piston  20 , with a flow-through passage, the fluency of oil liquid flow is improved and the power consumption of the pump body assembly is reduced. Currently, during running of a rotary cylinder compressor, when the rotation shaft of the pump body assembly is sliding with respect to the piston, the region of the rotation shaft in the piston impedes flowing of the oil liquid such that the oil liquid impedes movement of the piston and the rotation shaft and the power consumption of the pump body assembly is increased. 
     Specifically, the rotation shaft  30  penetrates through the sliding hole  2011  on the piston  20  and divides the portion inside the piston  20  into two cavities. During movement of the pump body assembly, the piston  20  reciprocates with respect to the rotation shaft  30 , and the two cavities increase and decrease periodically to achieve the oil pressing process. The shaft segment of the rotation shaft  30  in the sliding hole  2011  of the piston  20  will press the oil liquid to enable transfer of the oil liquid within the two cavities. The rotation shaft flow-through passage is disposed on the shaft segment of the rotation shaft  30  in the sliding hole  2011  so as to reduce impediment of the rotation shaft  30  to the oil liquid and reduce power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process, and thus reduce power consumption of the pump body assembly. 
     As shown in  FIGS.  16  and  18   , there are a plurality of rotation shaft flow-through passages which are spaced in the axial direction of the rotation shaft  30 . By setting a plurality of spaced rotation shaft flow-through passages on the rotation shaft  30 , during the oil pressing process, the oil liquid can be transferred via the plurality of rotation shaft flow-through passages, enlarging the flow path and reducing power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process. 
     In some embodiments, there are less than 4 rotation shaft flow-through channels. When there are more than 4 flow-through passages, too many rotation shaft flow-through passages will cause decrease in strength of the rotation shaft  30 , and during relative movement of the rotation shaft  30  and the piston  20 , the rotation shaft  30  is prone to break due to decrease in strength of the rotation shaft  30 . With less than 4 rotation shaft flow-through passages, the flow path of the oil liquid is enlarged, without affecting the strength of the rotation shaft  30 . 
     It should be noted that in the specific embodiments as shown in  FIGS.  16 - 19   , the rotation shaft flow-through passage is a passage disposed on the rotation shaft  30  to enlarge the flow path of the oil liquid. In the specific implementation(s), there may be multiple specific structures for the rotation shaft flow-through passage as long as the impediment of the rotation shaft  30  to the oil transfer in the sliding hole  2011  of the piston  20  can be reduced, and they will not be described herein one by one. 
     Hereinafter, according to different structures for the rotation shaft flow-through passage, the following specific implementations are provided for explanation. 
     In the specific implementations as shown in  FIGS.  16 - 17   , the sliding hole  2011  has a group of opposite hole wall faces of the sliding hole  2011 . The rotation shaft  30  is provided, on the shaft segment in the sliding hole  2011 , with a sliding fit face  3011  cooperating with the hole wall face of the sliding hole  2011 . The rotation shaft flow-through passage is a rotation shaft communication groove  3013  and is disposed on the sliding fit face  3011 . 
     Specifically, when the rotation shaft  30  moves with respect to the sliding hole  2011  of the piston  20 , the sliding fit face  3011  on the rotation shaft  30  is used to be in relative sliding fit with the hole wall face on the sliding hole  2011 . The rotation shaft communication groove  3013  is disposed on the sliding fit face  3011 . The sliding fit face  3011  presses the oil liquid during sliding relative to the hole wall face of the sliding hole  2011 . The oil liquid can be transferred via the rotation shaft communication groove  3013 , decreasing resistance between the rotation shaft  30  and the piston  20  and the oil liquid, and reducing power consumption of the pump body assembly. 
     It should be noted that the sliding fit face  3011  is a plane. This means that the hole wall face of the sliding hole  2011  is a plane. The sliding fit face  3011  reciprocates with respect to the hole wall face of the sliding hole  2011 . The rotation shaft communication groove  3013  is provided on a surface of the sliding fit face  3011 . 
     As shown in  FIGS.  17  and  19   , the rotation shaft communication groove  3013  has a width t 1  accounting for 5%-20% of a diameter R 1  of the shaft segment of the rotation shaft  30  in the sliding hole  2011 . When the width t 1  of the rotation shaft communication groove  3013  is too small, it cannot effectively improve fluency of oil liquid transfer during the oil pressing process and the effect of reduction in power consumption of the pump body assembly cannot be achieved. When the width t 1  of the rotation shaft communication groove  3013  is too large, the strength of the rotation shaft  30  will be affected and the rotation shaft  30  is prone to break during its movement with respect to the piston  20 . 
     It should be noted that the width t 1  of the rotation shaft communication groove  3013  may be varied according to different types of the rotation shaft  30  as long as the fluency of oil liquid can be improved and the power consumption of the pump body assembly during the oil pressing process can be reduced. 
     As shown in  FIGS.  17  and  19   , the rotation shaft communication groove  3013  has a depth hl accounting for 5%-20% of a diameter R 1  of the shaft segment of the rotation shaft  30  in the sliding hole  2011 . 
     Specifically, when the depth hl of the rotation shaft communication groove  3013  is too small, it cannot effectively improve fluency of oil liquid transfer during the oil pressing process and the effect of reduction in power consumption of the pump body assembly cannot be achieved. When the depth hl of the rotation shaft communication groove  3013  is too large, the strength of the rotation shaft  30  will be affected and the rotation shaft  30  is prone to break during its movement with respect to the piston  20 . 
     It should be noted that the depth hl of the rotation shaft communication groove  3013  may be varied according to different types of the rotation shaft  30  as long as the fluency of oil liquid can be improved and the power consumption of the pump body assembly during the oil pressing process can be reduced. 
     In the specific implementation as shown in  FIG.  18   , the sliding hole  2011  has a group of opposite hole wall faces of the sliding hole  2011 . The rotation shaft  30  is provided, on the shaft segment in the sliding hole  2011 , with a sliding fit face  3011  cooperating with the hole wall face of the sliding hole  2011 . The rotation shaft  30  is further provided, on the shaft segment in the sliding hole  2011 , with a group of connection faces  3016 , opposite to each other, for connecting two sliding fit faces  3011 . The rotation shaft flow-through passage is a rotation shaft flow-through hole  3012 , and rotation shaft flow-through hole  3012  penetrates through two connection faces  3016 . 
     Specifically, the rotation shaft  30  penetrates through the sliding hole  2011  of the piston  20  and divides the sliding hole  2011  into two cavities. During the oil pressing process, the oil liquid is transferred between the two cavities. The rotation shaft flow-through hole  3012  is disposed between the two connection faces  3016 , so as to improve fluency of oil liquid flow, reduce impediment of oil liquid to the rotation shaft  30  and the piston  20 , and reduce power consumption of the pump body assembly during the oil pressing process. 
     It should be noted that the sliding fit face  3011  is a plane such that a distance L 1  between the two sliding fit faces  3011  is greater than a diameter of the rotation shaft flow-through hole  3012  by 2 mm. The sliding fit face  3011  slides with respect to the hole wall face of the sliding hole  2011 , with the friction reduced by the planar design, and the distance L 1  between the two sliding fit faces  3011  is greater than the diameter of the rotation shaft flow-through hole  3012  by 2 mm, to ensure the strength of the rotation shaft  30 , and prevent the rotation shaft  30  from damage or breaking during running due to a too large diameter of the rotation shaft flow-through hole  3012 . 
     In some embodiments, the diameter of the rotation shaft flow-through hole  3012  is greater than or equal to 1 mm. when the diameter of the rotation shaft flow-through hole  3012  is less than 1 mm, the effect of reducing pump body assembly cannot be achieved. In order to improve fluency of oil liquid flow, it is necessary for the diameter of the rotation shaft flow-through hole to be greater than or equal to 1 mm. 
     As shown in  FIGS.  16  and  18   , the rotation shaft  30  comprises a long shaft segment  3014  and a short shaft segment  3015  which are connected in sequence, with the long shaft segment  3014  having a length greater than that of the short shaft segment  3015 . The long shaft segment  3014  is provided thereon with a sliding fit face  3011 . At least a portion of the long shaft segment  3014  extends into the sliding hole  2011 . 
     Specifically, the sliding fit face  3011  on the long shaft segment  3014  is in sliding fit with the hole wall face of the sliding hole  2011  in the piston  20 . The rotation shaft flow-through passage is disposed on the long shaft segment  3014  to achieve reduction in power consumption of the rotation shaft  30  and the piston  20  during the oil pressing process. 
     As shown in  FIGS.  16 ,  18 ,  19   , the diameter of the shaft segment in the sliding hole  2011  is greater than the diameter of the short shaft segment  3015 . A stepped shape is formed at an interface between an end face of the shaft segment and the short shaft segment  3015 , and a support face is formed at an interface between the end face of the shaft segment and the short shaft segment  3015 . 
     The pump body assembly in the present disclosure further comprises a cylinder sleeve  40 , and a cylinder  10  is rotatably arranged in the cylinder sleeve  40 . The cylinder  10  is provided thereon, in its radial direction, with a piston hole  106 . The piston  20  is slidably arranged in the piston hole  106 . The rotation shaft  30  penetrates through the piston  20  and drives the piston  20  to reciprocate in an extension direction of the piston hole  106 . The cylinder  10  rotates to cause rotation of the piston  20 . 
     Specifically, during the reciprocating movement of the piston  20  in the extension direction of the piston hole  106  driven by the rotation shaft  30 , the piston  20  presses the oil liquid to achieve the oil pressing process of the pump body assembly. The oil liquid is transferred within the two cavities formed by the rotation shaft  30  and the piston  20  and the cylinder  10 . The rotation shaft flow-through passage is disposed on the shaft segment of the rotation shaft  30 , so as to improve fluency of oil liquid transfer, to reduce impediment of the rotation shaft  30  to oil liquid transfer during flowing of the oil liquid and reduce power consumption of the pump body assembly during the oil pressing process. 
     As can be seen from the above description, in the above embodiments of the present disclosure, the following technical effects are achieved: 
     The flow-through passage is disposed on the shaft segment of the rotation shaft  30  in the sliding hole  2011  of the piston  20 , so as to improve fluency of oil liquid flow and reduce power consumption of the pump body assembly. Currently, during running of a rotary cylinder compressor, when the rotation shaft  30  of the pump body assembly is sliding with respect to the piston  20 , the region of the rotation shaft  30  in the piston  20  impedes flowing of the oil liquid such that the oil liquid impedes movement of the piston  20  and the rotation shaft  30  and the power consumption of the pump body assembly is increased. 
     Specifically, the rotation shaft  30  penetrates through the sliding hole  2011  on the piston  20  and divides the portion inside the piston  20  into two cavities. During movement of the pump body assembly, the piston  20  reciprocates with respect to the rotation shaft  30 , and the two cavities increase and decrease periodically to achieve the oil pressing process. The shaft segment of the rotation shaft  30  in the sliding hole  2011  of the piston  20  will press the oil liquid to enable transfer of the oil liquid within the two cavities. The rotation shaft flow-through passage is disposed on the shaft segment of the rotation shaft  30  in the sliding hole  2011  so as to reduce impediment of the rotation shaft  30  to the oil liquid and reduce power consumption of the piston  20  and the rotation shaft  30  during the oil pressing process, and thus reduce power consumption of the pump body assembly. 
     In order to solve the problem in prior art of impediment to oil liquid flow during use of rotary cylinder compressors, a flange structure can be optimized to reduce impediment of the flange structure to the piston  20 , thereby improving fluency of oil liquid flow to reduce power consumption of the pump body assembly. 
     Specifically, as shown in  FIGS.  20 - 29   , the pump body assembly comprises a cylinder  10  and a flange structure. The cylinder  10  is rotatably arranged. The flange structure is on a side of the cylinder  10  and has a positioning boss  6001  protruding in the cylinder  10 . The positioning boss  6001  is provided thereon with an avoidance recess  6002 . 
     As can be seen from the above description, in the above embodiment(s) of the present disclosure, the avoidance recess  6002  is disposed on the positioning boss  6001  to reduce impediment of the flange structure to the flow path and reduce power consumption of the compressor. Currently, the flange structure of the prior pump body seriously blocks the path in the flow path in the cylinder  10  and the piston  20  close to the side of the flange structure such that the frozen oil cannot be smoothly transferred in the flow path, resulting in increase in resistance to the rotation shaft  30  during rotation and increase in power consumption of the compressor. Specifically, when the flange structure is the lower flange  60 , the portion in the flow path close to the lower portion is prone to be blocked. 
     Specifically, the positioning boss  6001  of the flange structure protrudes in the cylinder  10 . By setting the avoidance recess  6002  on the positioning boss  6001 , the impediment of the positioning boss  6001  to the flow path in the cylinder  10  is reduced. During rotation of the cylinder  10 , the oil liquid in the cylinder  10  flows back and forth via the flow path in the cylinder  10 . When the oil liquid flows to the positioning boss  6001 , the oil liquid can flow along the avoidance recess  6002 , increasing the flow volume, thus reducing power consumption of the compressor and also reducing noise and vibration of the compressor. 
     As shown in  FIGS.  23 - 29   , the positioning boss  6001  is concentric with the flange structure. The positioning boss  6001  is formed integrally on the flange structure and is partially protruded in the cylinder  10  to position the cylinder  10  to prevent the cylinder  10  from inclination during rotation. Also, the flange structure has a load bearing ability. When the positioning boss  6001  is concentric with the flange structure, the eccentric force between the positioning boss  6001  and the flange structure is decreased and the stability of the flange structure and the positioning boss  6001  is increased, thus improving running stability of the pump body assembly and also prolonging the service lives of the flange structure and the positioning boss  6001 . 
     As shown in  FIGS.  23 - 29   , the flange structure further comprises a flange hole  6003  penetrating through the positioning boss  6001 . The flange hole  6003  is eccentric with respect to the center of the flange structure. The pump body assembly further comprises a rotation shaft  30  penetrating through the cylinder  10  and the flange hole  6003 . 
     Specifically, the rotation shaft  30  penetrates through the piston  20  and the cylinder  10 , and is inserted in the flange hole  6003 . Herein, the flange hole  6003  is eccentric with respect to the positioning boss  6001 . The positioning boss  6001  has a function of bearing the rotation shaft  30 , and thus the eccentric flange hole  6003  can effectively decrease the concentrated stress between the positioning boss  6001  and the flange structure, which is conducive to prolonging the service life of the flange structure and also convenient to provide the avoidance recess  6002  on the positioning boss  6001 . The avoidance recess  6002  enlarges the flow path of the oil liquid, decreases resistance of the oil liquid to the rotation shaft  30 , and reduces power consumption of the pump body assembly. 
     As shown in  FIGS.  23 - 29   , the positioning boss  6001  is in a shape of step, and comprises a first segment  6004  and a second segment  6005 . The first segment  6004  is far away from the center of the cylinder  10  than the second segment  6005 . The outer circumferential face of the first segment  6004  is matched with an inner wall face of the cylinder  10 . a surface of the second segment  6005  on the side facing towards the center of the cylinder  10  is used as a support face for supporting the rotation shaft  30  of the pump body assembly. The flange hole  6003  penetrates through the first segment  6004  and the second segment  6005 . 
     Specifically, the second segment  6005  and the first segment  6004  cooperate to form a structure in stepped shape. The outer circumferential face of the first segment  6004  and the inner surface of the cylinder  10  are matched, without affecting rotation of the cylinder  10 . An end face of the second segment  6005  facing towards the center of the cylinder  10  supports the rotation shaft  30 . The flange hole  6003  and the second segment  6005  are concentric. The first segment  6004  and the second segment  6005  cooperate to form the avoidance recess  6002 , thus enlarging the flow path in the cylinder  10 , reducing impediment to rotation of the rotation shaft  30 , and reducing power consumption of the pump body assembly. 
     It should be noted that in the specific embodiments as shown in  FIGS.  23 - 29   , the first segment  6004  and the second segment  6005  are both circular bosses. During practical production, it is not necessary for both the first segment  6004  and the second segment  6005  to be circular bosses. It is also possible that only one of the first segment  6004  and the second segment  6005  is a circular boss, or it is also possible that none of the first segment  6004  and the second segment  6005  is a circular boss, as long as the first segment  6004  can be matched with the inner face of the cylinder  10  without any impediment and the second segment  6005  can support the rotation shaft  30 . As there are various shapes and combination forms for the first segment  6004  and the second segment  6005 , no further specific embodiment will be additionally provided herein for explanation. 
     It should be noted that based on difference in position as disposed for the second segment  6005  with respect to the first segment  6004 , it is possible to form various shapes of the avoidance recess  6002 . As there are various shape combination forms for the, the combination forms will not be described one by one. Hereinafter, according to different shapes for the avoidance recess  6002 , different implementations are provided respectively for explanation. 
     In the specific implementations as shown in  FIGS.  23 - 27   , the first segment  6004  and the second segment  6005  are both circular bosses. The orthographic projection of the second segment  6005  on the first segment  6004  is not completely overlapped with the outer circumference of the first segment  6004 , and the avoidance recess  6002  is formed at a stepped face between the outer circumference of the second segment  6005  and the first segment  6004 . In this case, the avoidance recess  6002  is a recess in a crescent shape which has an outer circle concentric with the flange structure. 
     Specifically, the first segment  6004  and the second segment  6005  are both circular bosses. As the avoidance recess  6002  is formed at the stepped face between the outer circumference of the second segment  6005  and the first segment  6004 , when the outer circumference of the second segment  6005  is partially overlapped with the outer circumference of the first segment  6004 , the avoidance recess  6002  in a crescent shape is formed at the stepped face between the outer circumference of the second segment  6005  and the first segment  6004 . The avoidance recess  6002  in the crescent shape enlarges the flow path of the oil liquid, reduces impediment of the oil liquid to the rotation shaft  30 , and reduces power consumption of the pump body assembly. 
     In the specific implementation as shown in  FIG.  28   , the first segment  6004  and the second segment  6005  are both circular bosses. The orthographic projection of the second segment  6005  on the first segment  6004  is not completely overlapped with the outer circumference of the first segment  6004 . The first segment  6004  is further disposed thereon with a support rib  6006  extending towards a center of the cylinder  10 . The support rib  6006  is not higher than the second segment  6005 . At least one side surface of the support rib  6006  is flush with the outer circumference of the first segment  6004 . The support rib  6006  and the second segment  6005  are spaced apart, and the avoidance recess  6002  is formed between the support rib  6006  and the second segment  6005 . In this case, the avoidance recess  6002  has an irregular shape. Herein, in the specific embodiment(s), it is generally possible to select the support rib  6006  having a height same as that of the second segment  6005 . 
     Specifically, with the support rib  6006  disposed on the first segment  6004 , the support rib  6006 , the first segment  6004  and the second segment  6005  cooperate to form the avoidance recess  6002  in an irregular shape. The avoidance recess  6002  can enlarge the flow path in the cylinder  10 , decrease resistance between the rotation shaft  30  and the oil liquid, and reduce power consumption of the pump body assembly. Moreover, with the support rib  6006  added, the stability between the positioning boss  6001  and the cylinder  10  can be improved. 
     It should be noted that the area of the irregular shape is determined as being not greater than an end area of an end of the first segment  6004  facing towards the center of the cylinder  10 . 
     In the specific implementation as shown in  FIG.  29   , the first segment  6004  and the second segment  6005  are both circular bosses. The orthographic projection of the second segment  6005  on the first segment  6004  is not completely overlapped with the outer circumference of the first segment  6004 . The first segment  6004  is further disposed thereon with a support rib  6006  extending towards a center of the cylinder  10 . The support rib  6006  is not higher than the second segment  6005 . At least one side surface of the support rib  6006  is flush with the outer circumference of the first segment  6004 . The support rib  6006  and the second segment  6005  are at least partially connected, and the avoidance recess  6002  is formed between the support rib  6006  and the second segment  6005 . In this case, the avoidance recess  6002  has a crescent shape, and the outer circle of the crescent shape is eccentric with respect to the flange structure. 
     Specifically, with the support rib  6006  added between the second segment  6005  and the first segment  6004 , the stability between the positioning boss  6001  and the cylinder  10  can be improved, preventing the cylinder  10  from inclination. Moreover, the avoidance recess  6002  formed between the first segment  6004  and the second segment  6005  can enlarge the flow path in the cylinder  10 , decrease resistance between the rotation shaft  30  and the oil liquid, and reduce power consumption of the pump body assembly. 
     In a specific embodiment not shown, the first segment  6004  and the second segment  6005  are both circular bosses. The orthographic projection of the second segment  6005  on the first segment  6004  is not overlapped at all with the outer circumference of the first segment  6004  such that an avoidance recess  6002  is formed at a stepped face between the outer circumference of the second segment  6005  and the first segment  6004 . In this case, the avoidance recess  6002  is an annular recess. 
     Specifically, the first segment  6004  is not overlapped with the outer circumference of the second segment  6005 . An annular avoidance recess  6002  is formed at a stepped face between the outer circumference of the second segment  6005  and the first segment  6004 . The annular avoidance recess  6002  can enlarge the flow path, reduce impediment of the flange structure to the flow path, and reduce power consumption of the pump body assembly. 
     It should be noted that when the avoidance recess  6002  is an annular recess, it is possible for the inner and outer annular faces thereof to be concentric or eccentric. When the inner and outer annular faces are concentric or eccentric, the same technical effect can be achieved. That is, the annular avoidance recess  6002  can enlarge the flow path and reduce impediment of the rotation shaft  30  to the oil liquid. Therefore, the configuration of the inner and outer annular faces, either concentric or eccentric, will not be individually described herein. 
     As shown in  FIG.  25   , the avoidance recess  6002  has a depth h equal to 4%-25% of a diameter of the first segment  6004 . Specifically, the depth of the avoidance recess  6002  is limited by the diameter of the first segment  6004 , to prevent a too large depth of the avoidance recess  6002  from affecting stability of cooperation of the positioning boss  6001  and the flange structure with the rotation shaft  30  and the cylinder  10 . When the depth h of the avoidance recess  6002  equals to 4%-25% of the diameter of the first segment  6004 , the avoidance recess  6002  can enlarge the flow path of the oil liquid, decrease resistance to rotation of the rotation shaft  30 , and reduce power consumption, without affecting running stability of the pump body assembly. 
     As shown in  FIG.  25   , a wall thickness d of the second segment  6005  is 10%-80% of a maximum wall thickness D of the first segment  6004 . As the second segment  6005  is eccentric with respect to the flange structure and the first segment  6004  is concentric with respect to the flange structure, the second segment  6005  is thus eccentric with respect to the first segment  6004 . It should be noted that when the wall thickness of the second segment  6005  is 10%-80% of the maximum wall thickness of the first segment  6004 , the eccentricity ratio of the second section  6005  to the first section  6004  is constant, and will not change with the ratio of the wall thickness of the first segment  6004  to the maximum wall thickness of the second segment  6005 . Moreover, the wall thickness of the second segment  6005  is constant while the wall thickness of the first segment  6004  may be changed. By setting the avoidance recess  6002  on the stepped face between the second segment  6005  and the first segment  6004 , the effect of enlarging flow path is achieved to reduce power consumption of the pump body. 
     In some embodiments, the second segment  6005  has a wall thickness d equal to 20%-40% of a maximum wall thickness D of the first segment  6004 . Specifically, by further defining the wall thickness d of the second segment  6005  and maximum wall thickness D of the first segment  6004 , it can be seen that when the wall thickness d of the second segment  6005  equals to 20%-40% of the maximum wall thickness D of the first segment  6004 , the flow-through effect of the oil liquid in the flow path is the best, the resistance of the oil liquid to the rotation shaft  30  is the lowest, and the power consumption of the pump body assembly is the lowest. 
     As shown in  FIG.  25   , the avoidance recess  6002  has a depth h equal to 5%-60% of a height H of the flange structure. Specifically, when the depth h of the avoidance recess  6002  is less than 5%-60% of the height H of the flange structure, the depth of the avoidance recess  6002  on the positioning boss  6001  is too small, the first segment  6004  of the positioning boss  6001  will impede flow of the oil liquid in the flow path and the oil liquid will impede rotation of the rotation shaft  30 , resulting in increase in power consumption of the pump body assembly. When the depth h of the avoidance recess  6002  is greater than 5%-60% of the height H of the flange structure, the depth of the avoidance recess  6002  on the positioning boss  6001  is too large, resulting in decrease in strength of the positioning boss  6001  and decrease in stability of the pump body assembly during running, and the displacement the rotation shaft  30  and the cylinder  10 . 
     In some embodiments, the avoidance recess  6002  has a depth h equal to 15%-35% of a height H of the flange structure. Specifically, the depth h of the avoidance recess  6002  equal to 15%-35% of the height H of the flange structure is the further definition to the depth h of the avoidance recess  6002  equal to 5%-60% of the height H of the flange structure. When the depth h of the avoidance recess  6002  equals to 15%-35% of the height H of the flange structure, the avoidance recess  6002  can effectively enlarge the flow path of the oil liquid, reduce impediment of the oil liquid to the rotation shaft  30  during its rotation, and reduce power consumption of the pump body assembly. 
     The flange structure in the present disclosure comprises a lower flange  60 . The rotation shaft  30  has a long shaft segment and a short shaft segment, with the long shaft segment having a diameter greater than that of the short shaft segment, such that a rotation shaft support face is formed at an interface between the long shaft segment and the short shaft segment. The rotation shaft support face is supported at the positioning boss  6001 . The short shaft segment penetrates into the lower flange  60 . 
     Specifically, the second segment  6005  of the positioning boss  6001  on the supports the support face of the rotation shaft  30 . During rotation of the rotation shaft  30 , the avoidance recess  6002  on the lower flange  60  enlarges the flow path of the oil liquid in the cylinder  10 , resulting in reduction in impediment of the oil liquid to the rotation shaft  30  and reduction in power consumption. 
     The pump body assembly in the present disclosure further comprises a cylinder sleeve having a volume cavity in which the cylinder  10  is rotatably arranged. The cylinder  10  is provided, in its radial direction, with a piston hole  106 , the piston  20  is slidably arranged in the piston hole  106 , the rotation shaft  30  penetrates through the piston  20  and drives the piston  20  to reciprocate in an extension direction of the piston hole  106 , and the cylinder  10  rotates to cause rotation of the piston  20 . The flange structure is located at an end of the cylinder sleeve in its axial direction, and at least a portion of the rotation shaft  30  penetrates into the flange structure. 
     Specifically, the cylinder  10  in the cylinder sleeve is rotated synchronously with the rotation shaft  30 . The piston  20  reciprocates in the piston hole  106 . The relative movement between the piston  20  and the rotation shaft  30  enables oil liquid transfer within two flow paths formed by cooperation of the cylinder  10 , the piston  20  and the rotation shaft  30 . The two flow paths increase and decrease periodically with the reciprocating movement of the piston  20  to drive oil liquid transfer. The avoidance recess  6002  disposed on the positioning boss  6001  of the lower flange  60  can reduce impediment of the positioning boss  6001  to oil liquid flow in the flow path(s), decrease resistance between the rotation shaft  30  and the oil liquid, and reduce power consumption of the pump body assembly. 
     As can be seen from the above description, the above embodiment(s) of the present disclosure can achieve the following technical effect(s): 
     By setting the avoidance recess  6002  on the positioning boss  6001 , the impediment of the flange structure to the flow path is reduced and the power consumption of the compressor is reduced. Currently, the flange structure of the prior pump body seriously blocks the lower portion of the flow path in the cylinder  10  and the piston  20  such that the frozen oil cannot be smoothly transferred in the flow path, resulting in increase in resistance to the rotation shaft  30  during rotation and increase in power consumption of the compressor. 
     Specifically, the positioning boss  6001  of the flange structure protrudes in the cylinder  10 . By setting the avoidance recess  6002  on the positioning boss  6001 , the impediment of the positioning boss  6001  to the flow path in the cylinder  10  is reduced. During rotation of the cylinder  10 , the oil liquid in the cylinder  10  flows back and forth via the flow path in the cylinder  10 . When the oil liquid flows to the positioning boss  6001 , the oil liquid can flow along the avoidance recess  6002 , increasing the flow volume, thus reducing power consumption of the compressor and also reducing noise and vibration of the compressor. 
     Apparently, the embodiments as described above are only some embodiments of the present disclosure, rather than all embodiments. Any other embodiments obtained by those skilled in the art, based on the embodiments in the present disclosure and without any inventive work, will fall within the protection scope of the present disclosure. 
     It should be noted that the terms as used herein are only for describing specific implementations, and are not intended to limit the exemplary implementations according to the present application. As used herein, the singular form is intended to comprise the plural form, unless otherwise specified in the context. In addition, it should be understood that when the terms of “comprise” and/or “include” are/is used in the present description, it means that there are a feature, a step, an operation, a device, a component, and/or the combinations thereof. 
     Those as described above are only the preferred embodiments of the present disclosure, and are not used for limiting the present disclosure. For those skilled in the art, there may be various modifications and changes for the present disclosure. Any modification, equivalent substitution or improvement made within the spirit and principle of the present disclosure should be incorporated in the protection scope of the present disclosure. 
     Apparently, the embodiments as described above are only some embodiments of the present disclosure, rather than all embodiments. Any other embodiments obtained by those skilled in the art, based on the embodiments in the present disclosure and without any inventive work, will fall within the protection scope of the present disclosure. 
     It should be noted that the terms as used herein are only for describing specific implementations, and are not intended to limit the exemplary implementations according to the present application. As used herein, the singular form is intended to comprise the plural form, unless otherwise specified in the context. In addition, it should be understood that when the terms of “comprise” and/or “include” are/is used in the present description, it means that there are a feature, a step, an operation, a device, a component, and/or the combinations thereof. 
     It should be noted that the terms of ‘first”, “second” and the like in the description and claims and the above figures of the present application are used for distinguishing similar objects, rather than describing a specific order or sequence. It is understandable that such data as used may be exchanged under a suitable condition such that the implementations of the present application as described herein can be implemented in an order other than those depicted or described herein.