CN113847222A - Direct-current high-pressure plunger pump and coffee machine - Google Patents

Abstract

The invention provides a direct-current high-pressure plunger pump and a coffee machine. The piston assembly has a first end connected to the cam assembly and a second end in clearance fit with the piston channel. The piston assembly is provided with a cam movable cavity and a sliding fit part, the cylinder body and/or the driving assembly is provided with a limit part, and the sliding fit part is in limit fit with the limit part and slides along a first direction relative to the limit part; the cam component is positioned in the cam movable cavity and comprises a cam body and a rotating shaft, the cam body is fixed on the driving shaft, the rotating shaft is rotatably arranged on the cam body, and the outer peripheral wall of the rotating shaft is contacted with the inner peripheral wall of the cam movable cavity; the driving component drives the cam component to rotate and drives the piston component to reciprocate. The direct-current high-pressure plunger pump enables the interior of the cylinder body to reach higher pressure and reduces running resistance.

Description

Direct-current high-pressure plunger pump and coffee machine

Technical Field

The invention relates to the field of coffee making equipment, in particular to a direct-current high-pressure plunger pump and a coffee machine.

Background

Referring to fig. 1 to 3, a water pump used in a conventional coffee maker includes a connecting rod 101, a piston 102, a cam 103, a cylinder 104, and a motor, wherein the piston 102 is reciprocally mounted in the cylinder 104, the cam 103 is mounted on a driving shaft 105 of the motor, two ends of the connecting rod 101 are respectively hinged to the piston 102 and the cam 103, the motor drives the cam 103 to rotate and drives the connecting rod 101 to swing, and the connecting rod 101 drives the piston 102 to reciprocate, thereby increasing pressure in the cylinder 104.

In the water pump, in the process that the connecting rod 101 drives the piston 102 to move, the connecting rod 101 swings relative to the piston 102, so that the sealing performance between the piston 102 and the cylinder 104 is poor, and the connecting rod 101 not only has reciprocating movement but also swings, so that higher pressure in the cylinder cannot be achieved, and the operation resistance is large.

Disclosure of Invention

A first object of the present invention is to provide a direct-current high-pressure plunger pump capable of achieving a higher pressure inside a cylinder while reducing running resistance.

The second purpose of the invention is to provide a coffee machine with the direct-current high-pressure plunger pump.

In order to achieve the first object, the invention provides a direct-current high-pressure plunger pump, which comprises a cylinder body, a driving assembly, a cam assembly and a piston assembly, wherein an accommodating cavity and a pressurizing cavity which are communicated with each other are arranged in the cylinder body, and a piston channel which extends along a first direction is arranged on one side of the pressurizing cavity, which is close to the accommodating cavity. The drive assembly sets up in one side of cylinder body, and drive assembly's drive shaft stretches into and holds the chamber, and the axial perpendicular to first direction of drive shaft. The cam assembly is mounted on the drive shaft and is located within the receiving cavity. The piston assembly is installed and is held the intracavity, and the first end of piston assembly is connected with the cam subassembly, and the second end of piston assembly stretches into in the piston passageway, piston assembly and piston passageway clearance fit. The piston assembly is provided with a cam movable cavity and a sliding fit part, the cylinder body and/or the driving assembly is provided with a limiting part, and the sliding fit part is in limiting fit with the limiting part and slides along a first direction relative to the limiting part; the cam component is positioned in the cam movable cavity and comprises a cam body and a rotating shaft, the cam body is fixed on the driving shaft, the rotating shaft is rotatably arranged on the cam body, the axis of the rotating shaft is parallel to the axial direction of the driving shaft, and the outer peripheral wall of the rotating shaft is contacted with the inner peripheral wall of the cam movable cavity; the driving assembly drives the cam assembly to rotate and drives the piston assembly to reciprocate along the first direction.

According to the scheme, when the driving assembly drives the cam assembly to rotate, the rotating shaft of the cam assembly applies acting force to the piston assembly, and meanwhile, due to the matching of the sliding fit part on the piston assembly and the limiting part on the cylinder body/driving assembly, the piston assembly can only move back and forth along the first direction. Because the piston only moves along the first direction relative to the cylinder body and does not swing relative to the cylinder body, the sealing performance between the piston and the piston channel can be effectively ensured, and higher pressure can be achieved in the pressurizing cavity in the cylinder body. Meanwhile, because the piston does not swing relative to the cylinder body, the resistance of the piston in moving is smaller. In addition, the pivot is rotationally installed on the cam body, and consequently the frictional force between pivot and the piston is rolling friction, because the cam constantly produces the friction between the internal perisporium in pivoted in-process and cam activity chamber, through the setting of pivot, can reduce the frictional force between cam module and the piston, prevent to lead to the piston can not move to preset the position owing to cam module's wearing and tearing, and the effect of effective pressure boost can not be realized, its life that can effectively prolong direct current high pressure plunger pump.

The cam comprises a cam body, a rotating shaft, a cam shaft and a cam body, wherein the cam body is provided with a driving shaft and a driving shaft; the cam component further comprises a positioning pin which is fixed on the cam body and penetrates through the mounting groove, the rotating shaft is sleeved on the positioning pin through the central hole, the rotating shaft is located in the mounting groove, and part of the rotating shaft is exposed out of the opening.

It can be seen that the rotating shaft can be stably coupled to the cam body.

Preferably, the cam moving cavity comprises a first arc-shaped wall and a second arc-shaped wall which are oppositely arranged and connected end to end, the first arc-shaped wall is bent towards the pressurizing cavity, the second arc-shaped wall is bent towards the direction far away from the pressurizing cavity, and the plane of the central axis of the first arc-shaped wall and the central axis of the second arc-shaped wall passes through the axis of the driving shaft and is parallel to the first direction.

It can be seen that the shaft is movable along the first and second arcuate walls to ensure smooth movement of the piston assembly.

In a preferred scheme, the piston assembly comprises a piston, a sealing element, an elastic sealing ring and a fixing element; the piston comprises a cylindrical part and a piston part which are arranged along a first direction and connected, the cam movable cavity and the sliding fit part are both positioned on the cylindrical part, and the piston part is in sliding fit with the piston channel; the sealing element and the elastic sealing ring are arranged at the axial end, far away from the cylindrical part, of the piston part, the elastic sealing ring is located between the sealing element and the piston part, and the fixing element fixes the sealing element on the piston part along the first direction.

Therefore, the arrangement of the sealing element and the elastic sealing ring ensures that the pressurizing cavity and the accommodating cavity are effectively isolated, liquid in the pressurizing cavity is prevented from flowing into the accommodating cavity, the sealing element realizes axial and radial sealing of the piston channel, the elastic sealing ring further seals a gap between the piston and the sealing element, and the liquid is prevented from entering the accommodating cavity through the central hole of the sealing element.

Further, the sealing element is in interference fit with the piston channel; or a sleeve is arranged in the piston channel, and the sealing element is in interference fit with the sleeve.

The sealing element is made of Teflon material, fluororubber, special plastic or precise special ceramic, and the sleeve is made of metal material or ceramic material.

Therefore, through the interference fit between the sealing element made of Teflon and the like and the inner peripheral wall of the piston channel or the sleeve in the piston channel, on one hand, the sealing performance of the piston and the piston channel in the radial direction and the axial direction is guaranteed, on the other hand, the lubricating coefficient of the Teflon and the like is extremely low, and the Teflon and the like have good wear resistance, so that the sealing element cannot lose efficacy even after the piston performs reciprocating movement for many times, and the piston is guaranteed to smoothly slide in the piston channel. The sleeve made of the metal material or the ceramic material can improve the matching precision of the sleeve and the piston part and improve the wear resistance.

The piston assembly further comprises an elastic sealing ring and a pressing block; the pressing block is arranged on one side of the sealing element opposite to the elastic sealing ring, and the fixing element sequentially penetrates through the pressing block and the sealing element and then is fixedly connected with the piston; the elastic sealing ring is installed between the outer circumferential wall of the pressing block and the inner circumferential wall of the piston channel in a pressing mode.

Therefore, the stability of the sealing element mounted on the piston is guaranteed by the pressing block, and the sealing element is prevented from being stressed and deformed or falling off. And the arrangement of the elastic sealing ring ensures the axial and radial sealing performance between the pressing block and the piston channel.

In a preferable scheme, the top wall of the cylinder body is provided with a shaft hole; the free end of the driving shaft is rotatably arranged in the shaft hole; or a shaft sleeve is arranged in the shaft hole, and the free end of the driving shaft is rotatably arranged in the shaft sleeve; or a bearing is arranged in the shaft hole, and the free end of the driving shaft is rotatably arranged in the bearing.

Therefore, the arrangement of the shaft hole realizes the support of the free end of the driving shaft, and the driving shaft is prevented from shaking in the working process. And through set up axle sleeve or bearing in the shaft hole, can improve the wearability in shaft hole, prevent that the shaft hole from being worn and torn and the grow to can't realize the effective support to the free end of drive shaft. Meanwhile, through the arrangement of the shaft sleeve or the bearing, the rotating stability and smoothness of the driving shaft are ensured.

The sliding fit part comprises two sliding fit walls which are arranged in parallel, and the sliding fit walls are positioned on the outer peripheral wall of the piston assembly; the sliding fit wall is matched with the limiting wall to limit the piston to slide only along the first direction.

Therefore, the sliding fit wall is in limit fit with the limit wall, and the piston is guaranteed to slide only along the first direction.

In order to achieve the second object, the invention provides a coffee machine, which comprises the direct-current high-pressure plunger pump.

Drawings

Fig. 1 is a schematic structural diagram of a water pump piston for a coffee machine in a first position during movement.

Fig. 2 is a schematic structural view of a conventional water pump piston for a coffee maker moving to a second position.

Fig. 3 is a schematic structural view of a conventional pump piston for a coffee maker moving to a third position.

Fig. 4 is a cross-sectional view of an embodiment of the dc high pressure plunger pump of the present invention.

Fig. 5 is an assembly view of the drive shaft, cam assembly, cylinder block and piston assembly of an embodiment of the dc high pressure plunger pump of the present invention.

Fig. 6 is an exploded view of the drive shaft, cam assembly, cylinder block and piston assembly of an embodiment of the dc high pressure plunger pump of the present invention.

Fig. 7 is a cross-sectional view perpendicular to the axial direction of the drive shaft of an embodiment of the direct-flow high-pressure plunger pump of the present invention.

Fig. 8 is a cross-sectional view of a drive shaft, cam assembly, cylinder block and piston assembly of an embodiment of the dc high pressure plunger pump of the present invention.

Fig. 9 is a schematic structural diagram of the piston assembly in the first position during the movement process in the embodiment of the direct-flow high-pressure plunger pump of the invention.

FIG. 10 is a schematic diagram of the piston assembly of the embodiment of the DC high pressure plunger pump of the present invention moving to a second position.

Fig. 11 is a schematic structural diagram of the embodiment of the direct-flow high-pressure plunger pump of the invention when the piston assembly moves to the third position.

The invention is further explained with reference to the drawings and the embodiments.

Detailed Description

Referring to fig. 4, the coffee maker of the present embodiment includes a direct-flow high-pressure plunger pump 100, and the direct-flow high-pressure plunger pump 100 includes a cylinder block 1, a driving assembly 2, a cam assembly 3, and a piston assembly 4.

An accommodating cavity 11 and a pressurizing cavity 12 which are communicated with each other are arranged in the cylinder body 1, and a piston channel 13 which extends along a first direction is arranged on one side of the pressurizing cavity 12 close to the accommodating cavity 11. The driving assembly 2 is disposed at one side of the cylinder block 1, the driving assembly 2 includes a motor 22, a planetary reduction gear set 23 and a driving shaft 21, the driving shaft 21 and a rotating shaft 221 of the motor 22 are connected to the planetary reduction gear set 23 so as to transmit a driving force of the motor 22 to the driving shaft 21, the driving shaft 21 extends upward into the accommodating cavity 11, and an axial direction of the driving shaft 21 is perpendicular to the first direction. The cylinder body 1 is provided with a water inlet 121 and a water outlet 122 which are opposite to each other in the axial direction of the driving shaft 21, the water inlet 121 and the water outlet 122 are both communicated with the pressurizing cavity 12 and are respectively located at two opposite sides of the pressurizing cavity 12, a water inlet valve 123 is arranged in the water inlet 121, a water outlet valve 124 is arranged at the water outlet 122, the water inlet valve 123 and the water outlet valve 124 both comprise a spring 1231 and a sealing plug 1232, the spring 1231 is arranged at one side of the corresponding sealing plug 1232 close to the pressurizing cavity 12, the sealing plug 1232 is forced to seal the corresponding water inlet 121 by the restoring force of the spring 1231 of the water inlet valve 123, and the sealing plug 1232 is forced to seal the corresponding water outlet 122 by the restoring force of the spring 1231 of the water outlet valve 124.

Referring to fig. 4 to 8, a top cover 15 is disposed on the top of the cylinder block 1, a shaft hole 151 is formed in the top cover 15, a bearing 152 is disposed in the shaft hole 151, and the free end of the driving shaft 21 is rotatably mounted in the bearing 152. Preferably, the bearing 152 is an oil bearing. The top wall of the cylindrical portion 411 of the piston 41 is opened with a slide groove 414 extending along the first direction, the driving shaft 21 passes through the slide groove 414 and then is connected to the bearing 152, and the length of the slide groove 414 is greater than or equal to the displacement of the piston 41 in the first direction.

The piston assembly 4 is installed in the accommodating cavity 11, and the piston assembly 4 comprises a piston 41, a sealing element 42, an elastic sealing ring 43, a fixing element, an elastic sealing ring 45 and a pressing block 46, wherein the fixing element is a fastening screw 44. The piston 41 comprises a cylindrical part 411 and a piston part 412 which are arranged along a first direction and connected, a cam moving cavity 413 is arranged on the cylindrical part 411, the cam component 3 is installed on the driving shaft 21 and is positioned in the cam moving cavity 413, the cross section area of the cam moving cavity 413 is larger than that of the cam component 3, the cylindrical part 411 of the piston component 4 is positioned in the accommodating cavity 11 and is matched and connected with the cam component 3, the piston part 412 of the piston component 4 extends into the piston channel 13, a sleeve 14 is arranged in the piston channel 13, the sleeve 14 is made of a metal material, the sleeve 14 and the piston part 412 are integrally injection-molded, and the piston part 412 is in clearance fit with the inner peripheral wall of the sleeve 14 and can reciprocate along the extending direction of the piston channel 13.

As shown in fig. 7 and 8, the cam moving chamber 413 includes a first arc-shaped wall 4131 and a second arc-shaped wall 4132 which are oppositely disposed and connected end to end, the first arc-shaped wall 4131 is curved toward the pressurizing chamber 12, the second arc-shaped wall 4132 is curved away from the pressurizing chamber 12, and a plane in which a central axis of the first arc-shaped wall 4131 and a central axis of the second arc-shaped wall 4132 are located passes through an axis of the drive shaft 21 and is parallel to the first direction.

The seal 42 and the elastic seal ring 43 are both provided at the axial end of the piston portion 412 away from the cylindrical portion 411, and the elastic seal ring 43 is located between the seal 42 and the piston portion 412. The seal 42 is in the form of a disc-shaped ring and is made of teflon material, the seal 42 being an interference fit with the sleeve 14. The pressing block 46 is disposed on the opposite side of the sealing member 42 from the elastic sealing ring 43, and the axial end of the piston portion 412 away from the cylindrical portion 411 is provided with a threaded hole 4121, and the threaded hole 4121 is a blind hole, so that liquid is prevented from entering the accommodating chamber 11 through a gap between the threaded hole 4121 and the fastening screw 44, and the sealing performance is further improved. The fastening screw 44 passes through the pressing block 46 and the sealing member 42 in sequence in the first direction and is fixedly connected with the threaded hole 4121 of the piston portion 412, so that the sealing member 42 is fixed on the piston portion 412. An elastic seal ring 45 is press-fitted between the outer peripheral wall of the pressing piece 46 and the inner peripheral wall of the sleeve 14.

Referring to fig. 4 and fig. 6 to 8, the cam module 3 includes a cam body 31, a rotating shaft 32 and a positioning pin 33, the cam body 31 is fixed on the driving shaft 21, the rotating shaft 32 is rotatably mounted on the cam body 31, an axis of the rotating shaft 32 is parallel to an axial direction of the driving shaft 21, a mounting groove 311 facing a direction away from the driving shaft 21 is formed in a peripheral wall of the cam body 31, and a central hole 321 is formed in the rotating shaft 32 in an axial direction. The rotating shaft 32 is positioned in the mounting groove 311, a part of the rotating shaft 32 is exposed out of the opening 312, the positioning pin 33 axially penetrates through the cam body 31 and the central hole 321 of the rotating shaft 32, so that the rotating shaft 32 is connected to the cam body 31, the rotating shaft 32 can freely rotate around the central shaft of the positioning pin 33 by sleeving the rotating shaft 32 on the positioning pin 33, and the outer peripheral wall of the rotating shaft 32 is in contact with the inner peripheral wall of the cam movable cavity 413, so that the friction force of the cam assembly 3 in contact with the piston assembly 4 is reduced, and a force is provided for driving the piston assembly 4 to move.

As shown in fig. 7, a limiting portion is provided on the cylinder 1, the limiting portion includes a limiting wall 111 and a limiting wall 112 which are arranged in parallel and extend along a first direction, the limiting wall 111 and the limiting wall 112 are both located in the accommodating cavity 11, the piston assembly 4 is provided with a sliding fit portion, the sliding fit portion includes a sliding fit wall 415 and a sliding fit wall 416 which are arranged in parallel and extend along the first direction, the sliding fit wall 415 and the sliding fit wall 416 are located on an outer peripheral wall of the cylindrical portion 411 of the piston 41, the cylindrical portion 411 is located between the limiting wall 111 and the limiting wall 112, the sliding fit wall 415 is in contact with the limiting wall 111, and the sliding fit wall 416 is in contact with the limiting wall 112, so that the sliding fit wall and the limiting wall cooperate to limit the piston 41 to slide only along the first direction. In this embodiment, the diameter of the driving shaft 21 at the sliding groove 414 is substantially the same as the width of the sliding groove 414 of the piston 41, that is, the driving shaft 21 is in clearance fit with the sliding groove 414, so the portion where the driving shaft 21 is engaged with the sliding groove 414 is also a limiting portion, the sliding groove 414 on the piston 41 is a sliding engagement portion, and the limiting engagement formed by the two portions enables the piston 41 to slide only in the first direction.

Referring to fig. 9 to 11, when the driving shaft 21 of the driving assembly 2 drives the cam assembly 3 to rotate, the rotating shaft 32 of the cam assembly 3 applies a force to the inner circumferential wall of the cam moving cavity 413 of the piston 41, and at the same time, due to the cooperation of the sliding engagement portion on the piston assembly 4 and the limiting portion on the cylinder 1, the piston assembly 4 can only reciprocate along the first direction and does not swing relative to the piston channel 13.

Therefore, the piston only moves along the first direction relative to the cylinder body and does not swing relative to the cylinder body, so that the sealing performance between the piston and the piston channel can be effectively ensured, and the higher pressure can be achieved in the pressurizing cavity in the cylinder body. Meanwhile, because the piston does not swing relative to the cylinder body, the resistance of the piston in moving is smaller. In addition, the pivot is rotationally installed on the cam body, and consequently the frictional force between pivot and the piston is rolling friction, because the cam constantly produces the friction between the internal perisporium in pivoted in-process and cam activity chamber, through the setting of pivot, can reduce the frictional force between cam module and the piston, prevent to lead to the piston can not move to preset the position owing to cam module's wearing and tearing, and the effect of effective pressure boost can not be realized, its life that can effectively prolong direct current high pressure plunger pump.

In addition, the pivot also can be solid construction, and the both ends of pivot are provided with the articulated shaft, and the pivot passes through the articulated shaft and articulates with the cam body. Bearings may also be used instead of rotating shafts. The number of the rotating shafts can be more than two, and the rotating shafts are arranged in parallel or coaxially. The free end of the driving shaft of the motor can also be directly connected with the shaft hole on the top cover of the cylinder body, or a shaft sleeve can be arranged in the shaft hole, and the driving shaft is connected with the shaft sleeve in a matching way. The piston channel is also not provided with a sleeve, the piston part is in clearance fit with the inner peripheral wall of the piston channel, and the sealing element is in interference fit with the inner peripheral wall of the piston channel. The seal may also be made of other wear resistant materials. The piston assembly may also include one of a seal and an elastomeric seal ring to achieve both axial and radial sealing. A shaft sleeve can be arranged in the shaft hole of the top cover of the cylinder body, and the free end of the driving shaft can be rotatably arranged in the shaft sleeve; or instead of providing a sleeve or bearing in the shaft bore, the free end of the drive shaft is fitted directly into the shaft bore. The width of the slide groove may be larger than the diameter of the drive shaft, and the piston may be restricted to slide only in the first direction only by the slide-fitting wall being fitted with the stopper wall. The sealing element can also be made of materials such as fluororubber, special plastic or precise special ceramics. The sleeve may also be made of a ceramic material. The above-described modifications also achieve the object of the present invention.

Finally, it should be emphasized that the above-described preferred embodiments of the present invention are merely examples of implementations, not limitations, and various changes and modifications may be made by those skilled in the art, without departing from the spirit and scope of the invention, and any changes, equivalents, improvements, etc. made within the spirit and scope of the present invention are intended to be embraced therein.

Claims (10)

1. Direct current high pressure plunger pump includes:

the piston type air compressor comprises a cylinder body, wherein an accommodating cavity and a pressurizing cavity which are communicated with each other are arranged in the cylinder body, and a piston channel extending along a first direction is arranged on one side, close to the accommodating cavity, of the pressurizing cavity;

the driving assembly is arranged on one side of the cylinder body, a driving shaft of the driving assembly extends into the accommodating cavity, and the axial direction of the driving shaft is perpendicular to the first direction;

a cam assembly mounted on the drive shaft and located within the receiving cavity;

the piston assembly is arranged in the accommodating cavity, a first end of the piston assembly is connected with the cam assembly, a second end of the piston assembly extends into the piston channel, and the piston assembly is in clearance fit with the piston channel;

the method is characterized in that:

the piston assembly is provided with a cam movable cavity and a sliding fit part, the cylinder body and/or the driving assembly is/are provided with a limit part, and the sliding fit part is in limit fit with the limit part and slides along the first direction relative to the limit part;

the cam assembly is positioned in the cam movable cavity and comprises a cam body and a rotating shaft, the cam body is fixed on the driving shaft, the rotating shaft is rotatably arranged on the cam body, the axis of the rotating shaft is parallel to the axial direction of the driving shaft, and the outer peripheral wall of the rotating shaft is contacted with the inner peripheral wall of the cam movable cavity;

the driving component drives the cam component to rotate and drives the piston component to reciprocate along the first direction.

2. The direct current high pressure plunger pump of claim 1, wherein:

the peripheral wall of the cam body is provided with an installation groove with an opening facing away from the driving shaft, and the rotating shaft is provided with a central hole in an axial penetrating manner;

the cam component further comprises a positioning pin, the positioning pin is fixed on the cam body and penetrates through the mounting groove, the rotating shaft is sleeved on the positioning pin through the central hole, the rotating shaft is located in the mounting groove, and a part of the rotating shaft is exposed out of the opening.

3. The direct current high pressure plunger pump of claim 1, wherein:

the cam movable cavity comprises a first arc-shaped wall and a second arc-shaped wall which are oppositely arranged and connected end to end, the first arc-shaped wall faces the pressurizing cavity in a bending mode, the second arc-shaped wall faces away from the pressurizing cavity in a bending mode, and the plane where the central shaft of the first arc-shaped wall and the central shaft of the second arc-shaped wall are located penetrates through the axis of the driving shaft and is parallel to the first direction.

4. A direct-flow high-pressure plunger pump according to any one of claims 1 to 3, characterized in that:

the piston assembly comprises a piston, a sealing element, an elastic sealing ring and a fixing element;

the piston comprises a cylindrical part and a piston part which are arranged along the first direction and connected, the cam movable cavity and the sliding fit part are both positioned on the cylindrical part, and the piston part is in sliding fit with the piston channel;

the sealing element with the elastic sealing ring all sets up piston portion is kept away from the axial end of tube-shape portion, the elastic sealing ring is located the sealing element with between the piston portion, the mounting will along first direction the sealing element is fixed on the piston portion.

5. The direct current high pressure plunger pump of claim 4, wherein:

an interference fit of the seal with the piston channel; or

A sleeve is arranged in the piston channel, and the sealing element is in interference fit with the sleeve.

6. The direct current high pressure plunger pump of claim 5, wherein:

the sealing element is made of Teflon material, fluororubber, special plastic or precise special ceramic, and the sleeve is made of metal material or ceramic material.

7. The direct current high pressure plunger pump of claim 5, wherein:

the piston assembly further comprises an elastic sealing ring and a pressing block;

the pressing block is arranged on one side of the sealing element opposite to the elastic sealing ring, and the fixing element penetrates through the pressing block and the sealing element in sequence and then is fixedly connected with the piston;

the elastic sealing ring is installed between the outer circumferential wall of the pressing block and the inner circumferential wall of the piston channel in a pressing mode.

8. A direct-flow high-pressure plunger pump according to any one of claims 1 to 3, characterized in that:

the top wall of the cylinder body is provided with a shaft hole;

the free end of the driving shaft is rotatably arranged in the shaft hole; or

A shaft sleeve is arranged in the shaft hole, and the free end of the driving shaft is rotatably arranged in the shaft sleeve; or

A bearing is arranged in the shaft hole, and the free end of the driving shaft is rotatably arranged in the bearing.

9. A direct-flow high-pressure plunger pump according to any one of claims 1 to 3, characterized in that:

the limiting part comprises two limiting walls which are arranged in parallel, the limiting walls are positioned in the accommodating cavity, the sliding fit part comprises two sliding fit walls which are arranged in parallel, and the sliding fit walls are positioned on the outer peripheral wall of the piston assembly;

the sliding fit wall is matched with the limiting wall to limit the piston to slide only along the first direction.

10. Coffee machine, characterized in that it comprises a direct-flow high-pressure plunger pump according to any one of claims 1 to 9.

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