CN210889238U

CN210889238U - High-pressure pump

Info

Publication number: CN210889238U
Application number: CN201921527704.9U
Authority: CN
Inventors: 陈阳
Original assignee: Wuxi Xunyuan Precision Technology Co ltd
Current assignee: Wuxi Xunyuan Precision Technology Co ltd
Priority date: 2019-09-16
Filing date: 2019-09-16
Publication date: 2020-06-30
Anticipated expiration: 2029-09-16

Abstract

The utility model relates to a general machinery, a high-pressure pump for pumping liquid specifically says so. It comprises a housing and a pump head. Its characteristics are there is the cylindrical cam in the casing, are provided with the piston rod along the circumference of cylindrical cam in the casing in the cylindrical cam outside, and the one end of piston rod all passes the casing and stretches out outside, and the piston rod that is located the casing is served and all has a stopper, keeps away from stopper one side of piston rod and all is located the recess of cylindrical cam. The pump head links to each other with the casing, all has the axial through-hole on the pump head that the piston rod corresponds, and in piston rod one end stretched into the axial through-hole, there was a water check valve in the axial through-hole one end. The pump heads corresponding to the axial through holes are all provided with water inlet holes, the water inlet holes and the axial through holes are arranged in a one-to-one correspondence mode, the water inlet holes are communicated with the corresponding axial through holes, and the water inlet holes are all provided with water inlet one-way valves. A pump cover is fixed on one end of the pump head far away from the end cover, and a main water outlet is formed in the pump cover. The high-pressure pump has the advantages of small volume, simple structure and long service life.

Description

High-pressure pump

Technical Field

The invention relates to a general machine, in particular to a high-pressure pump for pumping liquid. It is especially suitable for high pressure cleaning pump and mining emulsion pump.

Background

High pressure pumps are used particularly widely in various industries as a general purpose machine for delivering fluids. At present, traditional high-pressure pump includes casing and pump head, and the pivot is connected with the piston through the crank connecting rod in the casing, and the piston is provided with the through-hole on the pump head that corresponds, has the inlet opening that is linked together with the through-hole on the pump head, and the piston is arranged in the through-hole, all has the check valve in the inlet opening and the through-hole one end of keeping away from the piston, keeps away from one of the pump head of end cover and serves and be fixed with the pump cover, and the pump covers and has total. The traditional high-pressure pump utilizes a rotating shaft to drive a piston to reciprocate in a through hole through a crank connecting rod, so that liquid is pumped. Traditional high-pressure pump need all be connected with the piston along its vertical a plurality of crank connecting rods that set up in order to guarantee pump liquid measure and pump liquid pressure power in the pivot, on the crank connecting rod, all is provided with the through-hole on the pump head that the piston corresponds, and the piston is the one-to-one form and is located the through-hole of pump head. In order to increase the number of crank connecting rods, the rotating shaft of the conventional high-pressure pump needs to be made long enough, however, the strength of the long rotating shaft is low, and a large diameter is needed to ensure the strength, resulting in a large volume of the whole high-pressure pump. Moreover, the crank connecting rod has a complex structure and higher cost. In addition, the crank connecting rod structure has more transmission points and larger abrasion, so that the service life of the whole high-pressure pump is shorter.

Disclosure of Invention

The invention aims to provide a high-pressure pump which is small in size, simple in structure and long in service life.

In order to solve the problems, the following technical scheme is provided:

a high pressure pump of the present invention includes a housing and a pump head. The characteristics are there is the cylindrical cam in the casing, be axial fixity between cylindrical cam and casing, the cooperation of circumference rotation form, be provided with the piston rod along cylindrical cam's circumference in the casing in the cylindrical cam outside, the piston rod all arranges along cylindrical cam's axial, the one end of piston rod all passes the casing and stretches out outward, be the cooperation of the axial activity form along the piston rod between piston rod and casing, it has the stopper all to be located on the piston rod one end in the casing, stopper one side of keeping away from the piston rod all is located cylindrical cam's recess, so that the cam rotates, the piston rod is along its axial reciprocating motion. The pump head is the column, and the pump head is located that the casing lateral wall outside that the piston rod corresponds, and it links to each other with the casing, is concentric setting between pump head and cylindrical cam, all has axial through hole on the pump head that the piston rod corresponds, is located that piston rod one end outside the casing stretches into in the axial through hole, and is the cooperation of sliding seal form between piston rod outer wall and axial through hole, keeps away from and has a water check valve in the axial through hole one end of piston rod, and the flow direction of play water check valve is for following the one end that axial through hole and piston rod link to each other to the other end. The pump head that the axial direction through-hole corresponds all has the inlet opening, is the one-to-one between inlet opening and the axial direction through-hole and describes arranging, and the inlet opening is linked together with the axial direction through-hole that corresponds, all has the check valve that intakes on the inlet opening, and the flow direction of the check valve that intakes is from radial inlet opening to axial direction through-hole. The pump head that keeps away from the end cover is served and is fixed with the pump cover, and the opening of pump cover is connected with the end cover in fixed seal form all around, go out the check valve of water and all be located the pump cover, and the pump covers and has total delivery port.

The water inlet holes are arranged along the radial direction of the pump head and are all located between the outer circular surface of the pump head and the corresponding axial through holes.

The outer side wall of the pump cover corresponding to the water inlet one-way valve is provided with connecting pipes which extend outwards in the radial direction, the connecting pipes are connected with the corresponding water inlet one-way valve through communicating pipes, the outer end face of the closed end of the pump cover is provided with an annular groove, the opening part of the annular groove is fixedly connected with an annular cover plate in a sealing mode, a main water inlet is formed in the annular cover plate, and the annular groove and the section of the pump cover between the connecting pipes are provided with flow channels.

All be connected with the directional rod on the section piston rod that is located the casing, directional rod is parallel with the piston rod, and the directional rod equals with the distance of piston rod to cylindrical cam center to the distance at cylindrical cam center, all has directional hole on the casing lateral wall that the directional rod corresponds, and the one end of directional rod is located the directional hole that corresponds, and is the sliding form cooperation between directional rod and the directional hole.

The shell is in a cylindrical shape with an end cover. The cylindrical cam comprises a cylinder body, a rotating shaft is integrally connected with the cylinder body in a concentric mode, two ends of the rotating shaft extend out of two ends of the cylinder body respectively, a groove of the cylindrical cam is located on the outer circular surface of the cylinder body, and the cylinder body is arranged in the shell in a concentric mode. An outer central pit is formed in the outer end face of the cylinder bottom of the shell, and an inner central pit is formed in the inner side wall of the end cover. There is the centre bore on the outer central pit, has the back lid in the outer central pit, and the back that the centre bore corresponds is covered and is stepped down the hole, the one end of pivot passes the centre bore in proper order and steps down the hole and stretch out outside the casing, has first conical bearing in that section pivot that the centre bore corresponds, has the first annular boss towards first conical bearing on the medial surface of back lid, have the second annular boss towards first conical bearing on the cylinder, first annular boss offsets with first conical bearing's outer lane, and second annular boss offsets with first conical bearing's inner circle. Keep away from the pivot one end of casing bobbin base and be located in the interior central pit, and there is second tapered bearing this of serving of pivot, there is the third annular boss towards second tapered bearing on the cylinder, has the fourth annular boss towards second tapered bearing in the interior central pit, and third annular boss offsets with the inner circle of second tapered bearing, and fourth annular boss offsets with the outer lane of second tapered bearing.

And wear-resistant copper sleeves are arranged between the piston rod and the shell.

A sealing sleeve is fixed in one end of the axial through hole far away from the water outlet one-way valve, the piston rod is located in the corresponding sealing sleeve, and an annular sealing ring is arranged between the inner side wall of the sealing sleeve and the piston rod, so that the piston rod is connected with the axial through hole in a sliding sealing manner.

A mandrel bearing is arranged on one side of a limiting block positioned in the groove of the cylindrical cam, the axis of the radial bearing is arranged along the radial direction of the cylindrical cam, and the outer diameter of the radial bearing is smaller than the width of the groove of the cylindrical cam.

And connecting pins are uniformly distributed between the pump head and the side wall of the shell corresponding to the piston rod, so that a space is reserved between the pump head and the shell.

The piston rod is divided into a first section body and a second section body, the first section body is connected with the side wall of the shell, the orientation rod is connected with the first section body, one end of the first section body, which is positioned outside the shell, is connected with the second section body through a coupler, and one end of the second section body, which is far away from the first section body, is positioned in the corresponding axial through hole. The shaft coupling all is arranged in the interval of pump head and casing, and the movement distance of piston rod is less than the interval length of pump head and casing.

By adopting the scheme, the method has the following advantages:

the invention is characterized in that a cylindrical cam is arranged in a shell, a piston rod is arranged in the shell, one end of the piston rod penetrates through the shell and extends out, a limiting block is arranged at one end of the piston rod which is positioned in the shell, one side of the limiting block far away from the piston rod is positioned in a groove of the cylindrical cam, a pump head is positioned at the outer side of the side wall of the shell corresponding to the piston rod and is connected with the shell, axial through holes are arranged on the pump heads corresponding to the piston rod, one end of the piston rod which is positioned outside the shell extends into the axial through holes, a water outlet one-way valve is arranged at one end of the axial through hole far away from the piston rod, water inlet holes are arranged on the pump heads corresponding to the axial through holes in a one-to-one correspondence manner, the water inlet holes are communicated with the corresponding axial through holes, water inlet one-way valves are arranged on the water. The high-pressure pump realizes liquid pumping by utilizing the cylindrical cam to drive the piston rod to reciprocate in the axial through hole. The pump hydraulic pressure can be provided by arranging enough piston rods around the cam, compared with the background art, the linear arrangement is changed into circumferential arrangement, the strength is ensured without increasing the length, and therefore the volume of the whole high-pressure pump is greatly reduced. Moreover, the high-pressure pump drives the piston rod to move by utilizing the cylindrical cam, and compared with a crank connecting rod, the structure of the whole high-pressure pump is greatly simplified, and the manufacturing cost is reduced. And the grooves of the cam drive the piston rod to linearly move, so that compared with the multi-stage transmission of a crank connecting rod, the abrasion points are reduced, the abrasion speed is reduced, and the service life of the whole high-pressure pump is greatly prolonged.

Drawings

FIG. 1 is a schematic view of the high pressure pump of the present invention;

FIG. 2 is a schematic sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic right-side view of FIG. 1;

FIG. 4 is a schematic structural view of FIG. 1 with the housing, rear cover, first screws and bolts omitted;

FIG. 5 is a schematic left side view of FIG. 4;

FIG. 6 is a schematic perspective view of the high pressure pump of the present invention;

FIG. 7 is an exploded perspective view of the high pressure pump of the present invention with the bolts, nuts, first and second screws omitted;

fig. 8 is an exploded perspective view of the housing in the high pressure pump of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1 to 8, a high-pressure pump of the present invention includes a housing 1 and a pump head 4. There is the cylindrical cam in casing 1, be axial fixity between cylindrical cam and casing 1, the cooperation of circumference rotation form, be provided with the piston rod along cylindrical cam's circumference in the casing 1 in the cylindrical cam outside, the piston rod all arranges along cylindrical cam's axial, the one end of piston rod all passes casing 1 and stretches out outside, be the cooperation of the axial activity form along the piston rod between piston rod and casing 1, it all has stopper 20 to be located on the piston rod one end in casing 1, stopper 20 one side of keeping away from the piston rod all is located cylindrical cam's recess, so that the cam rotates, the piston rod is along its axial reciprocating motion. Pump head 4 is the column, and pump head 4 is located the 1 lateral wall outside of that casing that the piston rod corresponds, and it links to each other with casing 1, is concentric the setting between pump head 4 and cylindrical cam, all has axial through hole 16 on the pump head 4 that the piston rod corresponds, and the piston rod one end that is located the casing 1 outside stretches into in the axial through hole 16, and is the sliding seal form cooperation between piston rod outer wall and axial through hole 16, has water check valve 19 in the axial through hole 16 one end of keeping away from the piston rod, and the flow direction of water check valve 19 is for following the one end that axial through hole 16 and piston rod link to each other to the other end. A sealing sleeve 22 is fixed in one end of the axial through hole 16 far away from the water outlet one-way valve 19, the piston rod is positioned in the corresponding sealing sleeve 22, and an annular sealing ring 39 is arranged between the inner side wall of the sealing sleeve 22 and the piston rod, so that the piston rod is connected with the axial through hole 16 in a sliding sealing manner. The pump head 4 corresponding to the axial through hole 16 is provided with water inlet holes 23, the water inlet holes 23 are arranged along the radial direction of the pump head 4, and the water inlet holes 23 are located between the outer circular surface of the pump head 4 and the corresponding axial through hole 16. The water inlet holes 23 and the axial through holes 16 are arranged in a one-to-one correspondence mode, the water inlet holes 23 are communicated with the corresponding axial through holes 16, the water inlet check valves 5 are arranged on the water inlet holes 23, and the flow direction of the water inlet check valves 5 is from the radial water inlet holes 23 to the axial through holes 16. A pump cover 32 is fixed on one end of the pump head 4 far away from the end cover 2, the periphery of an opening part of the pump cover 32 is fixedly and hermetically connected with the end cover 2, the water outlet check valves 19 are all positioned in the pump cover 32, and a main water outlet 34 is arranged on the pump cover 32. The outer side wall of the pump cover 32 corresponding to the water inlet one-way valve 5 is provided with a connecting pipe 7 which extends outwards in the radial direction, the connecting pipe 7 is connected with the corresponding water inlet one-way valve 5 through a communicating pipe 6, the outer end face of the closed end of the pump cover 32 is provided with an annular groove 24, the opening part of the annular groove 24 is fixedly connected with an annular cover plate 8 in a sealing mode, the annular cover plate 8 is provided with a main water inlet 33, and a flow channel 25 is arranged in the section of the pump cover 32 between the annular groove 24 and the connecting pipe 7. The pump head 4 and the side wall of the shell 1 corresponding to the piston rod are uniformly provided with connecting pins 3, so that a space is reserved between the pump head 4 and the shell 1. The piston rod is divided into a first section body 12 and a second section body 10, the first section body 12 is connected with the side wall of the shell 1, the directional rod 36 is connected with the first section body 12, one end of the first section body 12, which is positioned outside the shell 1, is connected with the second section body 10 through the coupler 11, and one end of the second section body 10, which is far away from the first section body 12, is positioned in the corresponding axial through hole 16. The shaft coupling 11 is located in the distance between the pump head 4 and the housing 1, and the movement distance of the piston rod is smaller than the length of the distance between the pump head 4 and the housing 1. The shell 1 is connected with the pump head 4 and the housing through bolts 13. The rear cover 27 is connected to the housing 1 by first screws 15, and the annular cover plate 8 is connected to the housing by second screws 9.

To prevent the piston rod from rotating, the stopper 20 is caused to move away from the groove of the cylindrical cam. The section of the piston rod located in the housing 1 is connected with an orientation rod 36, the orientation rod 36 is parallel to the piston rod, the distance from the orientation rod 36 to the center of the cylindrical cam is equal to the distance from the piston rod to the center of the cylindrical cam, the side wall of the housing 1 corresponding to the orientation rod 36 is provided with an orientation hole, one end of the orientation rod 36 is located in the corresponding orientation hole, and the orientation rod 36 is in sliding fit with the orientation hole.

In order to limit the cylindrical cam. The housing 1 is cylindrical with an end cap 2. The cylindrical cam comprises a cylinder 17, the cylinder 17 is concentrically and integrally connected with a rotating shaft 14, two ends of the rotating shaft 14 respectively extend out of two ends of the cylinder 17, a groove of the cylindrical cam is positioned on the outer circular surface of the cylinder 17, and the cylinder 17 is concentrically arranged in the shell 1. An outer central concave pit 35 is formed on the outer end face of the cylinder bottom of the shell 1, and an inner central concave pit 37 is formed on the inner side wall of the end cover 2. There is the centre bore on the outer central pit 35, has back lid 27 in the outer central pit 35, has the hole of stepping down on the back lid 27 that the centre bore corresponds, the one end of pivot 14 passes the centre bore in proper order and steps down the hole and stretch out outside casing 1, has first conical bearing 18 on that section pivot 14 that the centre bore corresponds, has the first annular boss 38 towards first conical bearing 18 on the medial surface of back lid 27, there is the second annular boss 28 towards first conical bearing 18 on the cylinder 17, and first annular boss 38 offsets with first conical bearing 18's outer lane, and second annular boss 28 offsets with first conical bearing 18's inner circle. One end of the rotating shaft 14 far away from the bottom of the shell 1 is located in the inner central concave pit 37, the end of the rotating shaft 14 is provided with a second conical bearing 26, the column 17 is provided with a third annular boss 30 facing the second conical bearing 26, the inner central concave pit 37 is provided with a fourth annular boss 29 facing the second conical bearing 26, the third annular boss 30 abuts against the inner ring of the second conical bearing 26, and the fourth annular boss 29 abuts against the outer ring of the second conical bearing 26.

In order to prolong the service life of the piston rod. And wear-resistant copper sleeves 31 are arranged between the piston rod and the shell 1.

In order to prolong the service life of the stop block 20. A mandrel bearing 21 is arranged on one side of a limiting block 20 in the groove of the cylindrical cam, the axis of the radial bearing 21 is arranged along the radial direction of the cylindrical cam, and the outer diameter of the radial bearing 21 is smaller than the width of the groove of the cylindrical cam.

The high-pressure pump realizes liquid pumping by utilizing the cylindrical cam to drive the piston rod to reciprocate in the axial through hole 16. The pump hydraulic pressure can be provided by arranging enough piston rods around the cam, compared with the background art, the linear arrangement is changed into circumferential arrangement, the strength is ensured without increasing the length, and therefore the volume of the whole high-pressure pump is greatly reduced. Moreover, the high-pressure pump drives the piston rod to move by utilizing the cylindrical cam, and compared with a crank connecting rod, the structure of the whole high-pressure pump is greatly simplified, and the manufacturing cost is reduced. And the grooves of the cam drive the piston rod to linearly move, so that compared with the multi-stage transmission of a crank connecting rod, the abrasion points are reduced, the abrasion speed is reduced, and the service life of the whole high-pressure pump is greatly prolonged. In the practical use process, the orientation rod 36 can be fixed on the end cover 2, the orientation sleeve is fixed on the piston rod, and the orientation of the piston rod is realized by the cooperation of the orientation sleeve and the orientation rod 36.

Claims

1. A high-pressure pump comprising a housing (1) and a pump head (4); the device is characterized in that a cylindrical cam is arranged in the shell (1), the cylindrical cam is axially fixed and circumferentially rotatably matched with the shell (1), a piston rod is arranged in the shell (1) at the outer side of the cylindrical cam along the circumferential direction of the cylindrical cam, the piston rod is axially arranged along the cylindrical cam, one end of the piston rod penetrates through the shell (1) and extends out of the shell, the piston rod is axially movably matched with the shell (1) along the piston rod, a limiting block (20) is arranged at one end of the piston rod in the shell (1), and one side of the limiting block (20) far away from the piston rod is arranged in a groove of the cylindrical cam so as to facilitate the rotation of the cam and the reciprocating movement of the piston rod along the axial direction of the piston rod; the pump head (4) is columnar, the pump head (4) is positioned on the outer side of the side wall of the shell (1) corresponding to the piston rod and is connected with the shell (1), the pump head (4) and the cylindrical cam are concentrically arranged, the pump head (4) corresponding to the piston rod is provided with an axial through hole (16), one end of the piston rod positioned outside the shell (1) extends into the axial through hole (16), the outer wall of the piston rod is matched with the axial through hole (16) in a sliding sealing manner, one end of the axial through hole (16) far away from the piston rod is provided with a water outlet one-way valve (19), and the flow direction of the water outlet one-way valve (19) is from one end of the axial through hole (16) connected with the piston rod to the other end; water inlet holes (23) are formed in the pump head (4) corresponding to the axial through holes (16), the water inlet holes (23) are arranged in a one-to-one correspondence manner with the axial through holes (16), the water inlet holes (23) are communicated with the corresponding axial through holes (16), water inlet check valves (5) are arranged on the water inlet holes (23), and the flow direction of the water inlet check valves (5) is from the radial water inlet holes (23) to the axial through holes (16); one end of the pump head (4) far away from the end cover (2) is fixedly provided with a pump cover (32), the periphery of an opening part of the pump cover (32) is fixedly and hermetically connected with the end cover (2), the water outlet check valve (19) is positioned in the pump cover (32), and the pump cover (32) is provided with a main water outlet (34).

2. The high-pressure pump as claimed in claim 1, characterized in that the inlet openings (23) are arranged in the radial direction of the pump head (4), the inlet openings (23) each being located between an outer circumferential surface of the pump head (4) and a corresponding axial through hole (16).

3. The high-pressure pump according to claim 2, characterized in that the outer side wall of the pump cover (32) corresponding to the water inlet check valve (5) is provided with a connecting pipe (7) extending radially outwards, the connecting pipes (7) are connected with the corresponding water inlet check valve (5) through a communicating pipe (6), the outer end surface of the closed end of the pump cover (32) is provided with an annular groove (24), the opening part of the annular groove (24) is fixedly connected with an annular cover plate (8) in a sealing manner, the annular cover plate (8) is provided with a total water inlet (33), and the section of the pump cover (32) between the annular groove (24) and the connecting pipe (7) is provided with a flow channel (25).

4. The high-pressure pump as claimed in claim 1, characterized in that the piston rods located in the housing (1) are each connected with an orientation rod (36), the orientation rods (36) are parallel to the piston rods, the distance from the orientation rods (36) to the center of the cylindrical cam is equal to the distance from the piston rods to the center of the cylindrical cam, the side walls of the housing (1) corresponding to the orientation rods (36) are each provided with an orientation hole, one end of each orientation rod (36) is located in the corresponding orientation hole, and the orientation rods (36) are slidably fitted with the orientation holes.

5. The high-pressure pump as claimed in claim 1, characterized in that the housing (1) is cylindrical with an end cap (2); the cylindrical cam comprises a cylinder (17), the cylinder (17) is concentrically and integrally connected with a rotating shaft (14), two ends of the rotating shaft (14) respectively extend out of two ends of the cylinder (17), a groove of the cylindrical cam is positioned on the outer circular surface of the cylinder (17), and the cylinder (17) is concentrically arranged in the shell (1); an outer central pit (35) is formed in the outer end face of the cylinder bottom of the shell (1), and an inner central pit (37) is formed in the inner side wall of the end cover (2); a central hole is formed in the outer central pit (35), a rear cover (27) is arranged in the outer central pit (35), a relief hole is formed in the rear cover (27) corresponding to the central hole, one end of the rotating shaft (14) sequentially penetrates through the central hole and the relief hole and extends out of the shell (1), a first conical bearing (18) is arranged on the section of the rotating shaft (14) corresponding to the central hole, a first annular boss (38) facing the first conical bearing (18) is arranged on the inner side surface of the rear cover (27), a second annular boss (28) facing the first conical bearing (18) is arranged on the cylinder (17), the first annular boss (38) abuts against the outer ring of the first conical bearing (18), and the second annular boss (28) abuts against the inner ring of the first conical bearing (18); keep away from pivot (14) one end at the bottom of casing (1) section of thick bamboo and be located in interior central pit (37), and there is second tapered bearing (26) this of pivot (14) to serve, have third annular boss (30) towards second tapered bearing (26) on cylinder (17), have fourth annular boss (29) towards second tapered bearing (26) in interior central pit (37), third annular boss (30) offsets with the inner circle of second tapered bearing (26), and fourth annular boss (29) offsets with the outer lane of second tapered bearing (26).

6. A high-pressure pump according to claim 1, characterized in that a wear-resistant copper bush (31) is provided between the piston rod and the housing (1).

7. The high-pressure pump as claimed in claim 1, characterized in that a sealing sleeve (22) is fixed in one end of the axial through hole (16) remote from the outlet check valve (19), the piston rod is located in the corresponding sealing sleeve (22), and an annular sealing ring (39) is arranged between the inner side wall of the sealing sleeve (22) and the piston rod, so that the piston rod is connected with the axial through hole (16) in a sliding sealing manner.

8. The high-pressure pump as claimed in claim 1, characterized in that a radial bearing (21) is provided on the side of the stopper (20) in the groove of the cylindrical cam, the axis of the radial bearing (21) being arranged in the radial direction of the cylindrical cam, the outer diameter of the radial bearing (21) being smaller than the groove width of the cylindrical cam.

9. The high pressure pump according to any of claims 1 to 8, wherein the pump head (4) and the side wall of the housing (1) corresponding to the piston rod are provided with connecting pins (3) uniformly, so that the pump head (4) and the housing (1) are spaced apart from each other.

10. The high-pressure pump according to claim 4, characterized in that the piston rod is divided into a first segment (12) and a second segment (10), the first segment (12) is connected to the side wall of the housing (1), the orientation rod (36) is connected to the first segment (12), one end of the first segment (12) located outside the housing (1) is connected to the second segment (10) through a coupling (11), and one end of the second segment (10) remote from the first segment (12) is located in the corresponding axial through hole (16); the shaft coupling (11) is located in the distance between the pump head (4) and the shell (1), and the movement distance of the piston rod is smaller than the distance between the pump head (4) and the shell (1).