JPH08254186A - Plunger pump - Google Patents

Abstract

PURPOSE: To increase pumping efficiency through provision of two-stage pump operation by a method wherein a slide hole which is formed in a pump housing and to which a plunger is coupled comprises large and small slide holes. CONSTITUTION: A slide hole 30 comprises a large slide hole part 30a with which a first seal member 44 is brought into slide contact and a small slide hole part 30b with which a second seal member 45 is brought into slide contact. The volume of a suction chamber 431 formed between the outer surface of a plunger 40 and the inner surface of a slide hole 30 between the two seal members 44 and 45 is changed according to axial reciprocating movement of the plunger 40. Namely, a pressure in the suction chamber 431 is increased or decreased and a pressure in a pump chamber 41 is decreased or increased through reciprocating slide in an axial direction of a pump chamber 40 and a plunger pump 5 is provided with two-stage pump operation. This constitution increases pump efficiency and also causes effective functioning of high viscosity working liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a pump chamber formed between a pump housing having a sliding hole and one end of a plunger fitted in the sliding hole so as to be reciprocally slidable. An annular first seal member that seals between the annular suction chamber and the pump chamber formed between the outer surface of the plunger and the inner surface of the sliding hole and is in sliding contact with the inner surface of the sliding hole;
An annular second seal member, which is in sliding contact with the inner surface of the slide hole with the suction chamber sandwiched between the first seal member and the second seal member, is provided between the discharge chamber and the pump chamber formed in the pump housing. The present invention relates to a plunger pump in which a discharge valve that opens and closes according to increase and decrease in pressure is provided, and an intake valve that opens and closes according to decrease and increase in pressure in the pump chamber is provided between the suction chamber and the pump chamber.

[0002]

2. Description of the Related Art Conventionally, such a plunger pump is disclosed in, for example, Japanese Utility Model Laid-Open No. 5-64481 and Japanese Patent Laid-Open No. 6-28.
It is already known from Japanese Patent No. 8345.

[0003]

Conventionally, in such a plunger pump, by opening the intake valve and closing the discharge valve according to the pressure reduction of the pump chamber when the plunger moves to the side of increasing the volume of the pump chamber. The working fluid is sucked into the pump chamber from the suction chamber, and the working fluid is closed by closing the suction valve and opening the discharge valve according to the pressure increase of the pump chamber when the plunger moves to the side that reduces the volume of the pump chamber. Although the pump is discharged from the pump chamber to the discharge chamber, it is desired to further increase the pump efficiency, and it is particularly desired to realize a plunger pump capable of exhibiting an effective pump action even for a high-viscosity hydraulic fluid. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plunger pump having improved pump efficiency.

[0005]

In order to achieve the above object, the invention according to claim 1 has a pump housing having a sliding hole and one end of a plunger fitted in the sliding hole so as to be reciprocally slidable. And a pump chamber is formed between the pump chamber and the annular suction chamber formed between the outer surface of the plunger and the inner surface of the sliding hole, and the pump chamber is sealed on the outer surface of the plunger by sliding on the inner surface of the sliding hole. An annular first seal member that is in contact with the first
A ring-shaped second seal member, which is in sliding contact with the inner surface of the slide hole with the suction chamber interposed therebetween, is mounted between the seal member and the seal member, and a pump chamber is provided between the discharge chamber and the pump chamber formed in the pump housing.・ A discharge valve that opens and closes according to the reduced pressure is provided.
In the plunger pump, an intake valve that opens and closes according to the pressure decrease / increase in the pump chamber is provided between the intake chamber and the pump chamber. In the plunger pump, the sliding hole is a large-diameter sliding hole portion that makes sliding contact with the first seal member. And has a smaller diameter than the large-diameter sliding hole,
And a small-diameter sliding hole portion for slidingly contacting the seal member.

According to a second aspect of the present invention, in addition to the structure of the first aspect of the present invention, the sliding hole between the large diameter sliding hole portion and the small diameter sliding hole portion has a first A step portion facing the seal member side is provided, and the plunger is provided with a regulation step portion facing the step portion.

According to the third aspect of the present invention, in addition to the structure of the second aspect of the invention, the inner surface of the sliding hole is larger in the pump housing than the small diameter sliding hole portion. An intake port is provided that opens to the end and communicates with the intake chamber.

[0008]

According to the structure of the invention described in claim 1, the volume of the annular suction chamber is changed in accordance with the axial reciprocating movement of the plunger. That is, the volume of the suction chamber is reduced according to the movement of the plunger in the direction of depressurizing the pump chamber, whereby the hydraulic fluid pressurized in the suction chamber is sucked into the pump chamber via the suction valve, and The volume of the suction chamber is increased in accordance with the movement of the plunger in the direction of increasing the pressure, and the working fluid is sucked from the reservoir or the like into the suction chamber whose pressure has been reduced. That is, the reciprocating sliding movement of the plunger in the axial direction increases and decreases the pressure in the suction chamber and decreases and increases the pressure in the pump chamber, so that the hydraulic fluid is discharged by the two-step pump action and the pump efficiency is increased. .

Further, according to the structure of the invention described in claim 2, the movement of the plunger toward the small-diameter sliding hole portion is restricted by the restriction step portion of the plunger facing the step portion of the sliding hole. Therefore, it is possible to prevent the plunger from moving more than necessary when the plunger pump is assembled or disassembled.

Further, according to the configuration of the invention as set forth in claim 3, the second seal member is caught on the opening end edge of the suction port to the inner surface of the sliding hole when the plunger is assembled into the pump housing and disassembled. It is possible to avoid the above, improve the assembling and disassembling properties, and avoid the damage of the second seal member.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention. FIG. 1 is an overall hydraulic circuit diagram of an anti-lock brake control device, and FIG. 2 is a longitudinal section of a plunger pump in a pump chamber depressurized state. FIG. 3 is a vertical cross-sectional view of the plunger pump in a pump chamber pressure-increasing state.

First, in FIG. 1, the master cylinder M is
An output port 2 that outputs a braking fluid pressure according to the depression of the brake pedal 1 is provided, and an antilock brake control device 3 is provided between the output port 2 and the wheel brake B.

The antilock brake control device 3 is
A reservoir 4 and a plunger pump 5 ₁ provided between the reservoir 4 and the output port 2 of the master cylinder M,
A switching valve means 6 is provided which can selectively connect the wheel brake B to the output port 2 and the reservoir 4 of the master cylinder M to connect them. Output port 2 of master cylinder M
Further, the damper 7 and the orifice 8 are connected between the plunger pump 5 _1, but the damper 7 may be omitted.

The switching valve means 6 is a normally open solenoid valve 9 provided between the output port 2 of the master cylinder M and the wheel brake B, and a normally closed solenoid valve provided between the wheel brake B and the reservoir 4. The normally open solenoid valve 9 allows the hydraulic fluid to flow from the wheel brake B side to the master cylinder M side when the hydraulic pressure on the wheel brake B side is higher than that on the master cylinder M side. The one-way valve 11 is connected in parallel.

The plunger pump 5 ₁ has a built-in suction valve 12 provided between it and the reservoir 4 and a discharge valve 13 provided between it and the output port 2 of the master cylinder M. The reservoir 4 has a piston 16 slidably fitted in the housing 15 with one end thereof facing the reservoir chamber 14.
Is urged by a spring 17 in a direction to reduce the volume of the reservoir chamber 14, and the normally closed solenoid valve 10 and the suction valve 12 are connected to the reservoir chamber 14.

[0017] Referring also to FIG. 2, the pump housing 18 ₁ of the plunger pump 5 ₁ includes a base 19 ₁ antilock brake control device 3 is provided, said substrate 19 ₁
The partition member 20 and the plug 21 which are inserted into the
It is fixed to the base 19 ₁ by a plug 22 which is screwed into the base body 19 _1.

A motor 23 is attached to the base body 19 ₁ .
A recess 2 for rotatably housing a bearing 26 mounted on a drive cam 25 provided on a drive shaft 24 of the motor 23.
7 is provided on the substrate 19 ₁ . Thus, the base body 19 ₁ has a screw hole 28 having one end opened on one surface 19a thereof, a fitting hole 29 having a diameter smaller than that of the screw hole 28 and coaxially connected to the other end of the screw hole 28, and a fitting hole. A sliding hole 30 having a diameter smaller than 29 and being coaxially connected to the other end of the fitting hole 29 and having the other end opened to the recess 27 is bored with an axis line orthogonal to the rotation axis line of the motor 23. To be done.

The partition member 20 and the plug 21 are inserted into the mounting hole 22 in a state where they are temporarily fixed to each other by a connecting member 31 formed of a synthetic resin in a cylindrical shape.
When the partition member 20 and the plug 21 are temporarily fixed to each other, the opposite ends of the partition member 20 and the plug 21 are lightly press-fitted into both ends of the connecting member 31, for example.

The partition wall member 20 has one surface 19a of the base body 29 _1.
Has a flange portion 20a on the opening end side that abuts on a step portion 32 formed in a tapered shape between the fitting hole 29 and the sliding hole 30 facing the side, and has a bottomed cylindrical shape with the plug 21 side as the closed end. It is formed. On the other hand, the plug 21 is provided with a step portion 20c between a large diameter portion 21a fitted into the fitting hole 29 and a small diameter portion 20b having the same outer diameter as the partition member 20. It is formed in a bottomed cylindrical shape with a step open to the partition member 20 side.

The partition member 20 is provided on the inner end side of the connecting member 31.
Is lightly press-fitted until the flange portion 20a is brought into contact with the inner end of the connecting member 31. The small diameter portion 21b of the plug 21 is lightly press-fitted to the outer end side of the connecting member 31 until the end surface of the small diameter portion 21b abuts the outer end surface of the partition member 20.

The axial length of the connecting member 31 is the same as the outer end of the connecting member 31 and the stepped portion 21c of the plug 21 when the partition member 20 and the plug 21 are temporarily fixed to each other by the connecting member 31. The ring-shaped mounting groove 33 is formed so that the partition member 20 and the plug 21 temporarily fixed by the connecting member 31 are inserted into the fitting hole 29. An annular seal member 34 that contacts the inner surface of the fitting hole 29 is mounted. By tightening the plug 22 is screwed into the screw hole 28 in contact with the plug 21 Thus, the partition member 20 and the plug 21, the substrate 19 so as to be held between the stepped portion 32 and the stopper 22 ₁ Will be fixed to.

A discharge chamber 35 is formed between the partition member 20 and the plug 21, and the partition member 20 and the connecting member 3 are formed.
1 and the inner surface of the fitting hole 29, the annular discharge passage 3
6 is formed, and on the end surface of the plug 21 on the partition member 20 side,
A groove 38 for communicating the discharge chamber 35 with the annular discharge passage 36 via a plurality of passages 37 provided in the connecting member 31,
It is provided so as to extend in the radial direction of the plug 21. Thus, one end side of the annular discharge passage 36 along the axial direction of the fitting hole 29 is sealed by the seal member 34, and the other end side of the annular discharge passage 36 has the flange portion 20a of the partition wall member 20 around the step portion 32 all around. It will be sealed by a close metal seal. Further, the base body 19 ₁ is provided with a discharge port 39 communicating with the annular discharge passage 36.
9 is connected to the normally open solenoid valve 9 (see FIG. 1) and the output port 2 of the master cylinder M (see FIG. 1).

The sliding hole 30 has a large-diameter sliding hole portion 30a, one end of which is connected to the fitting hole 29 through the step portion 32, and a smaller diameter than the large-diameter sliding hole portion 30a. And the large-diameter sliding hole portion 3b.
0a and the small-diameter sliding hole portion 30b, the sliding hole 30 has a smaller diameter than the large-diameter sliding hole portion 30a and a small-diameter sliding hole 30b.
The connecting hole portion 30d having a larger diameter is connected to the large-diameter sliding hole portion 30a through the step portion 30c and the taper step portion 30 is formed.
It is formed so as to be continuous with one end of the small-diameter sliding hole portion 30b via e.

A plunger 40 is slidably fitted in the sliding hole 30, and the plunger 40 is slidably fitted in a large-diameter sliding hole portion 30a of the sliding hole 30. The large diameter portion 40a, and the small diameter portion 40b slidably fitted in the small diameter sliding hole portion 30b of the sliding hole 30.
a on the outer circumference of the plunger 40 between the small diameter portion 40b and
An annular recess 40d is provided between the large diameter portion 40a and a restriction step 40c that faces the step 30c of the sliding hole 30.

The plunger 40 is fitted in the sliding hole 30 so as to be reciprocally slidable in the axial direction so as to form a pump chamber 41 between one end of the plunger 40 and the partition member 20, and the partition member 20 and the plunger 40. A return spring 42 is contracted between them. As a result, the other end of the plunger 40 protrudes from the sliding hole 30 and is always in sliding contact with the outer surface of the outer ring of the bearing 26 mounted on the drive cam 25. As shown, between the position where the volume of the pump chamber 41 is reduced to increase the pressure inside the pump chamber 41 and the position where the volume of the pump chamber 41 is increased to reduce the pressure inside the pump chamber 41 as shown in FIG. The plunger 40 is reciprocally driven in the axial direction.

An annular recess 4 is formed on the outer surface of the plunger 40.
A portion corresponding to the 0d, between the inner surface of the slide hole 30 is formed with a suction chamber 43 ₁ of the ring, the outer surface of the large diameter portion 40a of the plunger 40, the large diameter slide Doana portion 30a An annular first seal member 44, which slidably contacts the inner surface and seals between the pump chamber 41 and the suction chamber 43 _1, is attached, and the suction surface between the first seal member 44 and the outer surface of the small diameter portion 40b of the plunger 40 is provided. An annular second seal member 45, which is in sliding contact with the inner surface of the small-diameter sliding hole portion 30b with the chamber 43 ₁ interposed, is mounted. Therefore, the sliding hole 3 of the first seal member 44
The sliding contact diameter D ₁ of 0 on the inner surface is larger than the sliding contact diameter D ₂ of the inner surface of the sliding hole 30 of the second seal member 45.

[0028] the substrate 19 ₁ is suction port 46 ₁ is bored which communicates with the suction chamber 43 ₁ opens into the connecting hole portion 30d is larger in diameter than the small-diameter sliding hole portion 30b in the slide hole 30 The suction port 46 ₁ is connected to the reservoir chamber 14 of the reservoir 4 (see FIG. 1).

The plunger 40 is coaxially provided with a suction hole 48 which is always in communication with the suction chamber 43 ₁ via a filter 47 mounted in the annular recess 40d of the plunger 40 and is also in communication with the pump chamber 41. The suction hole 48 is opened / closed by the suction valve 12 according to the pressure decrease / increase in the pump chamber 41. The suction valve 12 includes a valve seat 49 provided at an edge of the suction hole 48 on the pump chamber 41 side, and a spherical valve body 50 that can be seated on the valve seat 49 and is housed in the pump chamber 41.
And a valve spring 51 that is compressed between the partition wall member 20 and the valve body 50 by exerting a spring force that urges the valve body 50 in the direction of sitting on the valve seat 49.

Further, the partition wall member 20 is provided with a discharge hole 52 which communicates with the pump chamber 41 and can communicate with the discharge chamber 35. The discharge hole 52 is provided with a discharge valve depending on increase / decrease in pressure of the pump chamber 41. It is opened and closed by 13. Thus, the discharge valve 13 is provided with a valve seat 53 provided at the end of the discharge hole 52 on the discharge chamber 35 side, and a spherical valve body 54 that can be seated on the valve seat 53 and is housed in the discharge chamber 35. And exerts a spring force for urging the valve body 54 in a direction to be seated on the valve seat 53,
1 and a valve spring 55 compressed between the valve body 54.

Next, the operation of the first embodiment will be described. The sliding hole 30 has a large-diameter sliding hole portion 30a for slidingly contacting the first seal member 44 and a small-diameter diameter smaller than the large-diameter sliding hole portion 30a. And the small-diameter sliding hole portion 30b for slidingly contacting the second seal member 45 is provided.
Volume of the suction chamber 43 ₁ of the ring that is formed between the inner surface of the outer surface and the slide hole 30 of the plunger 40 between 4,45 is allowed change in response to axial reciprocation of the plunger 40. That is, the volume of the suction chamber 43 ₁ is reduced in accordance with the movement of the plunger 40 in the direction of depressurizing the pump chamber 41, and the hydraulic fluid pressurized thereby is sucked into the pump chamber 41 via the suction valve 12. . In addition, the suction chamber 43 is moved according to the movement of the plunger 40 in the direction of increasing the pressure of the pump chamber 41.
The volume of ₁ is increased, whereby the working fluid is sucked into the suction chamber 43 ₁ whose pressure is reduced from the suction port 46 ₁ . That is, by reciprocally sliding the plunger 40 in the axial direction, the suction chamber 43 ₁ is increased and reduced in pressure, and the pump chamber 4 1
1 is reduced / increased, and the plunger pump 5 ₁ exerts a two-stage pumping action, so that the pump efficiency can be increased and the high-viscosity hydraulic fluid can effectively function.

Moreover, the sliding hole 30 has a large-diameter sliding hole portion 30.
Since the step portion 30c facing the first seal member 44 side is provided between a and the small-diameter sliding hole portion 30b, and the plunger 40 is provided with the regulation step portion 40c facing the step portion 30c.
When the regulation step portion 40c contacts the step portion 30c, the movement of the plunger 40 toward the recess 27 side of the base body 19 ₁ is regulated, and the plunger pump 5 with the motor 23 removed from the base body 19 ₁ It is possible to prevent the plunger 40 from moving more than necessary and slipping out toward the recess 27 side during the assembly or disassembly of item ₁ , thereby improving the assembly workability or the disassembly workability.

Further, the suction port 4 leading to the suction chamber 43 _1.
6 _1, the small-diameter sliding hole portion 3 in which the second sealing member 45 comes into sliding contact
Since it is provided in the base body 19 ₁ so as to open in the connection hole portion 30d having a diameter larger than 0b, the plunger 40
The second seal member 45 does not get caught on the opening edge of the suction port 46 ₁ when inserting the plunger 40 into the sliding hole 30 or when removing the plunger 40 from the sliding hole 30.
Assembling / disassembling workability can be further improved, and damage to the second seal member 45 can be prevented.

FIG. 4 shows a second embodiment of the present invention, and the portions corresponding to those of the first embodiment are designated by the same reference numerals.

The pump housing 18 ₂ of the plunger pump 5 _2, the cylinder body 57 to be inserted into the base body 19 _2, partition plate 58 and the plug 21, fixed to the base 19 ₂ in the plug 22 to be screwed into the base body 19 ₂ It is made up of

The base 19 ₂ has a screw hole 28 having one end opened on one surface 19a thereof, a fitting hole 29 having a diameter smaller than that of the screw hole 28 and coaxially connected to the other end of the screw hole 28, and a fitting hole. The diameter is smaller than 29, and one end is provided with the step portion 3 at the other end of the fitting hole 29.
A first mounting hole 59 that is coaxial with the second mounting hole, and a second mounting hole that is smaller than the first mounting hole 59 and has one end coaxially connected to the other end of the first mounting hole 59 and the other end opening into the recess 27. The hole 60 is formed with an axis line orthogonal to the rotation axis line of the motor 23.

The cylinder body 57 has a collar portion 57a that abuts the step portion 32, and a cylindrical portion 57b that has the same outer diameter as the outer diameter of the plug 21 and projects from the collar portion 57a toward the plug 21 side. An annular seal member 61, which is inserted into the first and second mounting holes 59 and 60 and contacts the inner surface of the second mounting hole 60, is attached to the outer surface of the cylinder body 57.

The partition plate 58 has a discharge hole 52 at the center thereof and is formed into a disk shape, and has a cylinder body 57.
Is abutted on the end surface of the cylindrical portion 57b. Further, the cylindrical portion 57b and the partition wall plate 58 are fitted to the connecting member 31, and the small diameter portion 21a of the plug 21 is fitted thereto, and the plug body 22 is screwed into the screw hole 28 and abuts on the plug 21. By tightening, the plug 21, the partition plate 58 and the cylinder body 57 are fixed to the base body 19 ₂ so as to be sandwiched between the step portion 32 and the plug body 22. With the cylinder body 57 fixed to the base body 19 ₂ ,
Of the reservoir 4 and the inner surface of the first mounting hole 59.
An annular path 62 leading to (see FIG. 1) is formed.

The cylinder body 57 has a pump chamber forming hole 63 whose one end is closed by a partition plate 58, one end of which is coaxially connected to the pump chamber forming hole 63, and the other end of which is the base body 19.
A sliding hole 64 for opening in the _second recess 27 is provided coaxially, and the sliding hole 64 has a smaller diameter than the pump chamber forming hole 63 and is a large diameter sliding hole 64 continuous to the pump chamber forming hole 63.
a and a small-diameter sliding hole portion 64b which is formed to have a smaller diameter than the large-diameter sliding hole portion 64a and opens in the recess 27.
Taper-shaped step portion 64c opposed to the zero regulation step portion 40c
Are coaxially connected so as to be interposed between the sliding hole portions 64a and 64b.

The plunger 40 which forms the pump chamber 41 with the partition plate 58 is slidably fitted in the sliding hole 64, and the first seal is mounted on the outer surface of the large diameter portion 40a of the plunger 40. The member 44 is in sliding contact with the inner surface of the large diameter sliding hole portion 64a, and the second seal member 45 mounted on the outer surface of the small diameter portion 40b of the plunger 40 is the small diameter sliding hole portion 64a.
sliding contact with b. Thus, the first and second sealing members 4
An annular suction chamber 43 ₂ is formed between the outer surface of the plunger 40 and the inner surface of the sliding hole 64 between the Nos. 4 and 45, and the cylinder body 57 has a larger diameter in the sliding hole 64 than in the small diameter sliding hole portion 64b. Is opened in the large-diameter sliding hole 64a, which is
_A suction port 46 ₂ is bored to allow ₂ to communicate with the annular passage 62.

The same effect as that of the first embodiment can be obtained by the second embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is possible.

[0043]

As described above, according to the invention of claim 1, the sliding hole has a large-diameter sliding hole portion for slidingly contacting the first seal member and a smaller diameter than the large-diameter sliding hole portion. A small-diameter sliding hole portion that is formed and makes sliding contact with the second seal member is provided. Therefore, by changing the volume of the suction chamber in accordance with the axial reciprocating movement of the plunger, a pumping action of two stages is generated. Efficiency can be increased.

According to a second aspect of the invention, in addition to the constitution of the first aspect of the invention, there is a first hole in the sliding hole between the large diameter sliding hole portion and the small diameter sliding hole portion. Since the step facing the seal member is provided and the plunger is provided with the restricting step facing the step, the plunger pump assembly is controlled by restricting the movement of the plunger toward the small-diameter sliding hole. It is possible to prevent the plunger from moving more than necessary at the time of attaching or disassembling and improve the workability.

According to the invention of claim 3, in addition to the structure of the invention of claim 2, in the pump housing, the inner surface of the sliding hole is larger than the small-diameter sliding hole. Since the suction port that opens to the suction chamber and is connected to the suction chamber is provided, it is possible to prevent the second seal member from being caught by the edge of the suction port opening to the inner surface of the sliding port, and to further improve workability during assembly and disassembly. It is possible to improve and prevent damage to the second seal member.

[Brief description of drawings]

FIG. 1 is an overall hydraulic circuit diagram of an antilock brake control device according to a first embodiment.

FIG. 2 is a vertical cross-sectional view of the plunger pump in a depressurized state of the pump chamber.

FIG. 3 is a vertical cross-sectional view of the plunger pump in a pressure increasing state of the pump chamber.

FIG. 4 is a sectional view corresponding to FIG. 2 of the second embodiment.

[Explanation of symbols]

5 ₁ , 5 ₂ ... Plunger pump 12 ... Suction valve 13 ... Discharge valve 18 ₁ , 18 ₂ ... Pump housing 30, 64 ... Sliding hole 30a, 64a ... Large diameter slide Doana portion 30b, 64b ... small-diameter sliding hole part 30c, 64c ... step portion 35 ... discharge chamber 40 ... plunger 40c ... restricting step portion 41 ... pump chamber 43 _1, 43 ₂ ... Suction chamber 44 ... First seal member 45 ... Second seal member 46 ₁ , 46 ₂ ... Suction port

Claims (3)

[Claims] 1. A pump housing having a sliding hole (30,64) and (18 _1, 18 _2), the sliding hole (30,64)
A pump chamber (41) is formed between the plunger (40) and one end of the plunger (40) fitted to the plunger (4) so as to be slidable back and forth.
0) the outer periphery of the plunger (40) and the annular suction chambers (43 ₁ , 43 ₂ ) formed between the inner surfaces of the sliding holes (30, 64) and the pump chamber (41) are sealed. The suction chamber (43 ₁ , 43 ₂ ) is sandwiched between the first seal member (44) and the annular first seal member (44) which is in sliding contact with the inner surface of the slide hole (30, 64). sliding hole and a second sealing member (45) of the annular sliding contact with the inner surface of the (30,64) is mounted, the pump housing (18 _1, 1
8 ₂ ) formed in the discharge chamber (35) and the pump chamber (4
A discharge valve (13) that opens and closes according to the increase / decrease in pressure of the pump chamber (41) is provided between 1), and the suction chamber (43 ₁ ,
43 ₂ ) and the pump chamber (41) between the pump chamber (4
In the plunger pump provided with the suction valve (12) that opens and closes according to the pressure reduction / increase of 1), the sliding holes (30, 6)
4) is a large-diameter sliding hole portion (30a, 64a) for slidingly contacting the first seal member (44) and a large-diameter sliding hole portion (30a, 6a).
4a) and has a smaller diameter than the second seal member (45).
And a small-diameter sliding hole portion (30b, 64b) for sliding contact with the plunger pump. 2. The sliding holes (30, 64a) and the small sliding holes (30b, 64b) are provided between the sliding holes (30, 64a).
64) includes a step (3) facing the first seal member (44) side.
0c, 64c), and the plunger (40) is
The regulation step (40) facing the step (30c, 64c)
The plunger pump according to claim 1, characterized in that c) is provided. The 3. A pump housing (18 _1, 18 _2), opened to the inner surface of the small-diameter sliding hole part (30b, 64b) sliding hole at the portion of the larger diameter side than the (30,64) inhalation Room (4
3 _1, 43 ₂₎ in communication with the suction port (46 _1, 46 ₂₎
The plunger pump according to claim 2, wherein the plunger pump is provided.