JPH1030576A - Plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of part item and the size of this pump. SOLUTION: This pump is provided with a cylinder 4 for supporting a plunger 6 so as to reciprocatingly-slide and a plug 5 for covering an attaching hole 3, which are assembled in the attaching hole 3 of a housing 1. The cylinder 4 and the plug 5 are fitted so as to be assembled integrally. Fluid is discharged between both of them through a discharging hole 4e from a pump chamber 12. A valve chamber 7 which stores a discharge valve 11 is formed, and the cylinder 4 and the plug 5 are formed so as to have the identical diameter over their roughly overall lengths in an assembled condition. The attaching hole 3 is formed with a stepped part 3a for regulating a movement in the inserting direction into the attaching hole 3 at a prescribed position by contact with at least one of the cylinder 4 and the plug 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a plunger pump.

[0002]

2. Description of the Related Art Conventionally, as a plunger pump, for example, a pump described in Japanese Patent Application Laid-Open No. 5-240157 is known. In this conventional plunger pump, a mounting hole is formed in the housing from one end face toward the cam, and the cylinder, the insert, and the plug are housed in the mounting hole in order from the back with the respective end faces abutting. The plug is screwed into a screw formed near the opening end of the mounting hole, while the cylinder is formed with a flange formed on the base end side on a step formed on the inner periphery of the mounting hole. , The movement of the cylinder, the insert and the plug in the axial direction is restricted, and the plunger whose tip is in contact with the cam is accommodated in the cylinder so as to be slidable in the axial direction. A pump chamber whose volume is changed according to sliding of the plunger is formed between the plunger and the cylinder, a valve chamber formed between the insert and the cylinder is communicated with the pump chamber, and the valve chamber is Balancing from pump room Discharge valve is provided to allow the flow of fluid only in a direction into the chamber, suction valve which allows only the intake to the pump chamber of the fluid is in the provided structure to the pump chamber.

[0003]

However, the above-described conventional plunger pump has the following problems. The axial dimension of the mounting hole is increased due to the axial arrangement of the cylinder, insert, and plug, and the axial length needed to screw the plug into the screw, thereby increasing the axial dimension of the mounting hole. The overall size of the pump increases. Since the screw portion for screwing the plug into the mounting hole must have an inner diameter larger than the outer diameter of the flange formed on the cylinder, the diameter of the mounting hole in the radial direction increases. The overall dimensions of the housing and the pump are increased. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has been made to reduce the number of parts and the radial and axial dimensions of the mounting hole so as to reduce the size of the plunger pump. It is intended for planning.

[0004]

Means for Solving the Problems In order to achieve the above object, an invention according to claim 1 is provided with a cam member housed in a housing and rotated by driving means, and one end of which is brought into contact with the cam member. A plunger reciprocating with the rotation of the cam member, and a sliding hole for supporting the plunger in a reciprocally slidable manner, and a reciprocating slide of the plunger between the bottom of the sliding hole and the plunger. A pump chamber having a volume that fluctuates with movement is formed, a cylinder attached to a mounting hole formed in the housing, a plug closed to the housing by closing the mounting hole, and a fluid to the pump chamber. A plunger pump provided with a suction valve that allows only suction of water and a discharge valve that allows only discharge from the pump chamber, wherein the cylinder and the plug are fitted and integrally assembled. Fluid is discharged from the pump chamber through a discharge hole between the two, a valve chamber accommodating the discharge valve is formed, and these cylinders and plugs are substantially assembled in their assembled state. The mounting hole is formed with the same outer diameter, and the mounting hole is formed with a step portion that contacts at least one of the cylinder and the plug and restricts the movement in the insertion direction into the mounting hole at a predetermined position. It is characterized by.

[0005] The invention according to claim 2 is characterized in that the step is formed at a position deep in the mounting hole and at a position where the tip end surface of the cylinder abuts when the cylinder is assembled. I do.

According to a third aspect of the present invention, the cylinder has a large-diameter portion disposed on the inner side of the mounting hole and an outer diameter smaller than the large-diameter portion. A small-diameter portion disposed on the opening side; and the plug has an outer diameter substantially equal to the outer diameter of the large-diameter portion of the cylinder, and an inner diameter into which the small-diameter portion can be inserted and fitted. The plug and the cylinder are integrally formed by fitting a small diameter portion of the cylinder into the fitting hole, and the plug is fixed to the mounting hole by caulking. It is characterized by the following.

According to a fourth aspect of the present invention, a flange is formed on the plug so as to protrude in the outer peripheral direction, and the flange can be inserted into an opening end of the mounting hole, so that the plug is larger than a general portion of the mounting hole. A large-diameter portion having an inner diameter formed to a large diameter is formed, and when the cylinder and the plug are inserted into the mounting holes, the flange of the plug is arranged in the large-diameter portion of the mounting hole. The plug is fixed to the housing by plastically deforming the large diameter portion of the mounting hole so as to press the flange.

According to a fifth aspect of the present invention, in the plunger pump according to the fourth aspect, when the small-diameter portion of the cylinder and the fitting hole of the plug are fitted, the large-diameter portion and the small-diameter portion of the cylinder are connected to each other. The stepped portion due to the diameter difference and the tip of the plug are separated from each other to form a sealing groove therebetween,
The seal groove is provided with a seal member defining a suction side and a discharge side.

According to a sixth aspect of the present invention, in the plunger pump according to the fourth aspect, the step portion according to the first aspect is formed by a step portion due to a diameter difference between a large diameter portion and a general portion of the mounting hole. It is characterized by comprising.

According to a seventh aspect of the present invention, the cylinder includes:
A press-fit hole is formed in the cylinder base end portion formed at the same outer diameter over the entire length and arranged at the opening end of the mounting hole when the cylinder is inserted into the mounting hole, in the axial direction from the base end surface. At the same time, a thin-walled caulking portion is formed on the outer periphery of the press-fitting hole, and the plug is press-fitted into the press-fitting hole, whereby the caulking portion is caulked on the inner periphery of the mounting hole.

The invention according to claim 8 is characterized in that a caulking groove is formed in a circumferential direction on an outer periphery of the caulking portion.

[0012]

According to the first aspect of the invention, the movement of the cylinder and the plug in the insertion direction is regulated at a predetermined position by the step formed in the mounting hole, and the cylinder or the plug is fixed. Further, in the present invention, the cylinder and the plug are fitted and integrated to form a valve chamber therebetween, and
The outer diameter of the integrated body is formed to have the same outer diameter over substantially the entire length. Therefore, as compared with the prior art, the axial dimension is reduced by the amount of the insertion member between the cylinder and the plug is eliminated, and the compact can be formed.

According to the second aspect of the present invention, the movement of the cylinder in the insertion direction is restricted by abutting the tip end surface of the cylinder against the step deep inside the mounting hole. As described above, since the movement is restricted by the cross section of the cylinder, it is not necessary to expand the cylinder or the plug and the mounting hole in the radial direction.
The overall radial dimension can be reduced.

According to the third aspect of the present invention, the small diameter portion of the cylinder is fitted into the fitting hole of the plug to integrate the cylinder and the plug, and the plug is caulked and fixed in the mounting hole. In the caulking of the plug, in the invention according to claim 4,
When the cylinder and plug are integrally inserted into the mounting hole, the flange formed on the outer periphery of the plug is arranged in the large diameter portion of the mounting hole, and the cylinder and plug integrated by the step of the mounting hole With the movement in the insertion direction restricted, the housing at the large-diameter portion of the mounting hole is plastically deformed so as to press the flange. According to the fifth aspect of the present invention, when the sealing member is provided on the outer periphery of the one in which the cylinder and the plug are integrated, when the small-diameter portion of the cylinder and the fitting hole of the plug are fitted, the tip of the plug is A seal groove is formed between the cylinder and a step due to a difference in diameter of the cylinder, and a seal member is mounted in the seal groove.
Therefore, the groove processing for forming the seal groove becomes unnecessary.
Further, in the invention described in claim 6, the movement of the cylinder and the plug in the insertion direction is regulated at the stepped portion due to the difference in diameter between the large-diameter portion and the general portion of the mounting hole.

According to the seventh aspect of the present invention, when assembling, first, the cylinder is inserted until the movement is restricted by the step portion.
Thereafter, the plug is pressed into the press-fit hole at the base end of the cylinder. As a result, the caulked portion at the base end of the cylinder is pushed out in the outer peripheral direction and caulked to the inner periphery of the mounting hole. In addition,
According to the eighth aspect of the present invention, at the time of this caulking, the housing bites into the caulking groove to be caulked more strongly.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is sectional drawing which shows the plunger pump of FIG. In the figure, reference numeral 1 denotes a housing, in which a cam member 2 rotated by a motor (not shown) is housed, and a cam member 2
A pair of mounting holes 3 are formed coaxially in a direction orthogonal to the axial direction of the cam member 2 with the. This mounting hole 3
Is a step 3a formed on the inner periphery of one end, and the step 3
A main part 3b formed in the direction from the other end toward the other end, and a large-diameter hole 3c formed at the opening end of the other end to have a slightly larger diameter than the main part 3b are formed. Further, in the main part 3b,
The suction passage 1a and the discharge passage 1b are opened apart from each other.
At positions a and 1b, a circumferentially shallow intake groove 3d and a discharge groove 3e are formed by contouring or U-shaped processing. Since one set of mounting holes 3 and the internal configuration thereof are the same, only one of them is shown.

The mounting hole 3 houses a cylinder 4 and a plug 5. That is, the cylinder 4 accommodates a plunger 6 described later, and has a sliding hole 4 therein.
a large-diameter portion 4b formed on the outer periphery at a distal end located on the left side in the figure with an outer diameter slightly smaller than the inner diameter of the mounting hole 3, and a base end on the right side in the figure. And a small diameter portion 4c formed to have an outer diameter smaller than the large diameter portion 4b. Further, the cylinder 4
A communication hole 4d for communicating the sliding hole 4a and the suction groove 3d is formed through the large diameter portion 4b. The plug 5
The outer diameter of the general portion is formed to be the same as the outer diameter of the large diameter portion 4b of the cylinder 4, and the outer end of the small diameter portion 4c of the cylinder 4 is fitted to the left end in the drawing. A hole 5a is formed, and a valve chamber 7 is drilled in the axial direction from the bottom of the fitting hole 5a.
A flange portion 5b slightly smaller in diameter than the large diameter portion 3c is formed, and a communication hole 5c for communicating the valve chamber 7 with the discharge groove 3e is formed to penetrate in the direction orthogonal to the axis. By fitting the fitting hole 5a of the plug 5 and the small diameter portion 4c of the cylinder 4, the plug 5 and the cylinder 4 are integrally assembled, and the tip of the plug 5 and the diameter of the cylinder 4 O-ring 8a between the step due to the difference
Is formed in the seal groove 9a. Further, seal grooves 9b and 9c having substantially the same dimensions as the seal grooves 9a are formed on the outer periphery of the distal end portion of the cylinder 4 and the outer periphery of the intermediate portion of the plug 5, and O-rings 8b and 8c are mounted respectively. I have. Incidentally, the O-ring 8a defines a suction groove 3d and a discharge groove 3e, and the O-ring 8b defines the suction groove 3d and the cam 2a.
The O-ring 8c defines the discharge groove 3e and the outside.

Next, the plunger 6, the intake valve 10, and the discharge valve 11 housed in the cylinder 4 will be described. As shown in the figure, the plunger 6 has a suction hole 6a formed at one end at an axial center portion, and a communication hole 6b extending from the bottom to the outer periphery of the suction hole 6a is formed to penetrate in a direction orthogonal to the axis. A seal ring 6d is fitted into a seal groove 6c formed on the outer circumference of the seal 6.
A pump chamber 12 is formed between one end of the plunger 6 and the bottom of the slide hole 4a. The pump chamber 12 communicates with the valve chamber 7 through a discharge hole 4e formed at the base end of the cylinder 4. In the pump chamber 12, a return spring 13 whose one end is seated at the bottom of the slide hole 4a and urges the plunger 6 in the direction of pressing the plunger 6 against the cam member 2 (left direction in the drawing), and the suction hole 6a A suction valve ball 10a that constitutes the suction valve 10 with the opening end, and a suction valve spring 10b that urges the suction valve ball 10a in the seating direction are provided. That is, the suction valve 10
The valve is opened when the pressure in the pump chamber 12 is lower than the pressure in the suction hole 6a, and is closed when the pressure in the pump chamber 12 is higher than the pressure in the suction hole 6a.

In the valve chamber 7, a discharge valve ball 11a seated at the open end of the discharge hole 4e and forming a discharge valve 11 with the open end, and the discharge valve ball 11a is urged in the seating direction. A discharge valve spring 11b is provided. That is, the discharge valve 11 opens when the pressure in the pump chamber 12 is higher than the pressure in the valve chamber 7, and conversely closes when the pressure in the pump chamber 12 is lower than the pressure in the valve chamber 7. Is configured.

Next, a procedure for assembling the plunger pump according to the first embodiment will be described. First, the O-ring 8a is attached to the small diameter portion 4c of the cylinder 4, and the O-ring 8a is moved to the step with the large diameter portion 4b. Next, the discharge valve spring 11b is seated on the bottom of the valve chamber 7 of the plug 5 and the discharge valve ball 11a is disposed at the tip thereof. Then, the small diameter portion 4c of the cylinder 4 is attached to the bottom of the fitting hole 5a of the plug 5. Until they fit. Thereby, the cylinder 4 and the plug 5 are assembled integrally. Before or after the assembling operation, O-rings 8b and 8c are mounted in the seal grooves 9b and 9c formed in the cylinder 4 and the plug 5, respectively. Next, the suction valve spring 10b and the return spring 13 are seated inside and outside at the bottom of the sliding hole 4a of the cylinder 4, and after the suction valve ball 10a is disposed at the tip of the suction valve spring 10b, the seal ring 6d is removed. The mounted plunger 6 is inserted into the slide hole 4a.

Next, the cylinder 4 and the plug 5 with the plunger 6 set are inserted into the mounting holes 3 of the housing 1.
Is inserted until the tip end surface of the cylinder 4 comes into contact with the step portion 3a, and then the inside of the large-diameter portion 3c of the mounting hole 3b is caulked, that is, plastically deformed.
b is fixed to the housing 1. The assembly is completed by the above operations.

Next, the operation of the first embodiment will be briefly described. When the cam member 2 rotates about the eccentric rotation center O1, the plunger 6 slides back and forth in the axial direction, and the pump chamber 1
When the volume of the pump chamber 12 increases, the pressure in the pump chamber 12 becomes low, so that the suction valve 10 is opened and the fluid in the suction passage 1a flows through the suction groove 3d, the communication hole 6d, and the suction hole 6a.
Inhaled in 2. The fluid sucked into the pump chamber 12 is compressed when the volume of the pump chamber 12 is reduced,
The discharge valve 11 is opened to be discharged into the valve chamber 7, and further,
The liquid is discharged from the valve chamber 7 to the discharge path 1b through the communication hole 5c and the discharge groove 3e.

The plunger pump according to the first embodiment described above has the following effects. Since the valve chamber 12 is formed between the cylinder 4 and the plug 5 by fitting the cylinder 4 and the plug 5, the number of parts is reduced as compared with the related art because the insert is eliminated, thereby reducing the cost. In addition, the assemblability is improved as compared with the case where the cylinder 4 and the plug 5 are separately assembled into the mounting holes 3. The outer diameter of the cylinder 4 and the plug 5 is configured to be substantially the same over the entire assembly in the assembled state. For the above three reasons, the entire diameter of the cylinder has been abolished because the positioning flange on the outer periphery of the cylinder 4 has been eliminated, and the configuration in which the mounting hole 3 is caulked and the plug 5 is fixed to the screw has been eliminated. The dimension in the direction is reduced, and the configuration can be made compact. By eliminating the insert between the cylinder 4 and the plug 5 as described above, and by fixing the plug 5 instead of screwing it into a screw, the axial dimension is reduced and the configuration is compact. Can be. Since all the sealing structures are provided in the cylinder 4 and the plug 5 and no sealing groove is formed in the mounting hole 3, machining of the mounting hole 3 is facilitated. Since the suction groove 3d and the discharge groove 3e formed in the mounting hole 3 are formed by boring, the processing is easy. The cylinder 4 and the plug 5 have three seal grooves 9a,
When forming the cylinders 9b and 9c, the seal groove 9a, which is one of them, is formed by the tip end surface of the plug 5 and the step portion of the cylinder 4 when the cylinder 4 and the plug 5 are fitted. With this configuration, the number of steps for groove processing is reduced, so that the working efficiency can be improved and the cost can be reduced. Next, other embodiments will be described. In describing the other embodiments, the same components as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. Only the differences between the first embodiment and the first embodiment will be described, and the same effects will be omitted.

First, a second embodiment will be described. FIG. 2 is a cross-sectional view illustrating a plunger pump according to a second embodiment.
The structure of the plug 25 differs from that of the first embodiment. The mounting hole 23 is larger in the large diameter portion 3 than in the first embodiment.
c is not provided, and this mounting hole 23 is constituted by a step portion 3a and a main portion 3b, and the main portion 3b is formed to have the same inner diameter all the way to the opening edge. Corners are cut at the edges.

The entire length of the cylinder 24 is substantially equal to the depth of the mounting hole 23.
It has the same outer diameter (slightly smaller than the inner circumference of the mounting hole 23) over the entire length. A sliding hole 4a is formed from the distal end side, while a press-fitting hole 24a is formed from the base end side, and a thin caulked portion 24b is formed on the outer periphery of the press-fitting hole 24a. Further, a caulking groove 24c is formed in the caulking portion 24b in the circumferential direction.

The plug 25 is formed in a substantially cylindrical shape having an outer diameter slightly larger than the inner diameter of the press-fitting hole 24a of the cylinder 24, and a corner at the outer periphery of the tip is cut to form a slope. ing. Further, a hole is drilled from the tip of the plug 25 to form the valve chamber 7, and a communication groove 25 a is formed on the open end side of the valve chamber 7 in the outer peripheral direction. The cylinder 24 has a communication hole 24d which connects the communication groove 25a and the discharge groove 3e, and further has a position between the step 3a and the suction groove 3d, and a position between the step portion 3a and the suction groove 3d. 3e, the seal groove 29
a, 29b are formed, and O-rings 28a, 28b are mounted in the respective grooves 29a, 29b.

Next, the main points of the assembling procedure according to the second embodiment will be described. The cylinder 24 to which the plunger 6 and the suction valve 10 are assembled is inserted into the mounting hole 23 until the tip of the cylinder 24 comes into contact with the step 3a. Next, the plug 25 to which the discharge valve 11 is assembled is inserted into the press-fit hole 2 at the base end of the cylinder 24.
The plug 4a is driven until the tip of the plug 25 comes into contact with the bottom of the press-fit hole 24a. At this time, since the outer circumference of the plug 25 is larger in diameter than the inner circumference of the press-fitting hole 24a of the cylinder 24, the outer circumference of the caulking portion 24b of the cylinder 24 is swaged to the inner circumference of the mounting hole 23, especially in the drawing. The housing is plastically deformed so as to enter the crimping grooves 24c as shown in FIG.

In the second embodiment described above, the radial and axial dimensions can be reduced and the structure can be made compact as in the first embodiment. In particular, in the second embodiment, the plug 25 is connected to the cylinder. Since the cylinders 24 are press-fitted into the 24 press-fitting holes 24a and have the same diameter throughout, the radial dimension can be further reduced to make the cylinder compact. Also,
Since the large-diameter portion 3c is eliminated in the mounting hole 23, the configuration can be made more compact than in the first embodiment.

Next, a third embodiment shown in FIG. 3 will be described. In the third embodiment, the step in the first and second embodiments is omitted in the mounting hole 33, and the positioning of the cylinder 4 and the plug 5 in the insertion direction is performed by the main portion 3b and the large diameter portion 3c of the mounting hole 33. This is an example in which the process is performed at a step between the steps.

[0030]

As described above, in the plunger pump according to the first aspect, the cylinder and the plug are fitted and integrally assembled to form a valve chamber between the two, and the two are assembled. Since the outer diameter of the plunger pump is substantially the same over the entire length in the state, the axial and radial dimensions of the plunger pump can be reduced, and the plunger pump can be downsized.
According to the second aspect of the present invention, the distal end surface of the cylinder is abutted against the step at the back of the mounting hole to restrict the movement of the cylinder in the insertion direction. Therefore, the effect that the size can be reduced can be obtained. According to the third and fourth aspects of the present invention, since the cylinder and the plug are integrally formed and the plug is caulked and fixed in the mounting hole, the shaft is not required as compared with the prior art in which a thread is formed in the mounting hole. An effect is obtained that the size can be reduced by suppressing the dimension in the direction. According to the fifth aspect of the present invention, since the small diameter portion of the cylinder and the fitting hole of the plug are fitted to form a seal groove between the tip of the plug and the step portion due to the difference in diameter of the cylinder, the seal is formed. Groove processing for forming grooves is not required, and the effect of reducing manufacturing labor and cost can be obtained. According to the sixth aspect of the present invention, the movement of the cylinder and the plug in the insertion direction is restricted by the step portion due to the difference in diameter between the large diameter portion and the general portion of the mounting hole. In the configuration in which the flange is formed (claim 4), it is not necessary to form a step portion in the depth of the mounting hole, so that an effect is obtained that the configuration can be simplified and the labor and cost for manufacturing can be reduced. According to the seventh aspect of the present invention, the plug is press-fitted into the press-fitting hole formed in the cylinder base end, and the caulked portion of the cylinder base end is caulked to the inner periphery of the mounting hole. The diameter dimension becomes the outer diameter dimension of the cylinder, and the effect that the size in the radial direction can be reduced and the size can be reduced can be obtained. In the invention according to claim 8, since the caulking groove is formed on the outer periphery of the caulking portion according to claim 7, the caulking portion is strongly caulked, and an effect that high sealing performance and fixing performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plunger pump according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a plunger pump according to Embodiment 2 of the present invention.

FIG. 3 is a sectional view showing a plunger pump according to Embodiment 3 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Cam member 3 Mounting hole 3a Step 3b Main part 3c Large diameter part 4 Cylinder 4a Sliding hole 4b Large diameter part 4c Small diameter part 5 Plug 5a Fitting hole 5b Flange 6 Plunger 7 Valve chamber 8a O-ring (seal) 9a seal groove 10 suction valve 11 discharge valve 12 pump chamber 23 mounting hole 24 cylinder 24a press-fit hole 24b caulking portion 24c caulking groove 33 mounting hole

Claims (8)

[Claims] A cam member accommodated in a housing and rotated by a driving means; a plunger having one end abutting on the cam member and reciprocating with the rotation of the cam member; A sliding hole movably supported is formed, and a pump chamber whose volume varies with reciprocal sliding of the plunger is formed between the bottom of the sliding hole and the plunger. A cylinder fixed to the housing by closing the mounting hole, a suction valve that allows only fluid to be sucked into the pump chamber, and a discharge valve that allows only discharge from the pump chamber. Wherein the cylinder and the plug are fitted and integrally assembled, and a fluid is discharged from the pump chamber between the two via a discharge hole. In addition, a valve chamber for accommodating the discharge valve is formed, and the cylinder and the plug are formed to have the same outer diameter over substantially the entire length in a state where both are assembled. A plunger pump characterized in that a step portion is formed, which abuts at least one of the plugs and regulates the movement in the insertion direction into the mounting hole at a predetermined position. 2. The method according to claim 1, wherein the step portion is formed at a position deep in the mounting hole and at a position where a tip end surface of the cylinder abuts when the cylinder is assembled. Plunger pump. 3. A large-diameter portion disposed on the inner side of the mounting hole and an outer diameter smaller than the large-diameter portion of the cylinder, and the cylinder is disposed on the opening side of the mounting hole. The plug has an outer diameter substantially equal to the outer diameter of the large diameter portion of the cylinder, and has a fitting hole with an inner diameter into which the small diameter portion can be inserted and fitted. The plug and the cylinder are integrally formed by fitting a small diameter portion of the cylinder into the fitting hole, and the plug is fixed to the mounting hole by caulking. Item 3. A plunger pump according to item 1 or 2. 4. A flange is formed on the plug so as to protrude in an outer peripheral direction. The flange is insertable into an opening end of the mounting hole, and the inner diameter of the mounting hole is larger than that of a general portion of the mounting hole. When the cylinder and the plug are inserted into the mounting hole, the flange of the plug is arranged in the large-diameter portion of the mounting hole,
4. The plunger pump according to claim 3, wherein the plug is fixed to the housing by plastically deforming the large-diameter portion of the mounting hole of the housing so as to press the flange in this state. 5. The plunger pump according to claim 4, wherein when the small-diameter portion of the cylinder and the fitting hole of the plug are fitted, a step portion due to a difference in diameter between the large-diameter portion and the small-diameter portion of the cylinder. And the tip of the plug is separated from each other to form a sealing groove therebetween, and a seal member defining a suction side and a discharge side is mounted in the sealing groove. Plunger pump. 6. The plunger pump according to claim 4, wherein the step portion is a step portion due to a diameter difference between a large diameter portion and a general portion of the mounting hole. 7. The cylinder has the same outer diameter over its entire length, and has a cylinder base end disposed at the opening end of the mounting hole when inserted into the mounting hole of the cylinder, and having a shaft from a base end surface. A press-fitting hole is formed in the direction, and a thin-walled caulking portion is formed on the outer periphery of the press-fitting hole. By pressing a plug into the press-fitting hole, the caulking portion is caulked on the inner periphery of the mounting hole. The plunger pump according to claim 1, wherein the plunger pump is provided. 8. The plunger pump according to claim 7, wherein a caulking groove is formed in a circumferential direction on an outer periphery of the caulking portion.