JP2019190395A - Piston pump - Google Patents

Abstract

To provide a piston pump capable of reducing a size and a weight while securing strength of a housing.SOLUTION: In a heat pump 100, an inner peripheral face of a housing hole 102 formed on a housing 101 has a first inner peripheral face 102a having a first inner diameter, a second inner peripheral face 102b having a second inner diameter smaller than the first inner diameter, and a restriction slant face 102c continuously reduced in diameter in a direction along an axis from the first inner diameter to the second inner diameter so that it is kept into contact with a guide member 119, and it connects the first inner peripheral face 102a and the second inner peripheral face 102b. The guide member 119 has a contact slant face 119e reduced in diameter to be kept into contact with the restriction slant face 102c in a state of being housed in the housing hole 102, and a cross-sectional shape on a plane including the axis of the contact slant face 119e is agreed with a cross-sectional shape on a plane of the restriction slant face 102c.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piston pump.

  Conventionally, for example, a piston pump disclosed in Patent Document 1 below is known. This conventional piston pump includes a seal member that seals the bottomed cylindrical cylinder member and the outer periphery of the piston, a backup ring, and a guide ring that supports the outer periphery on the rear side of the piston. And. The guide member is formed in a cylindrical shape having a rectangular cross section, and is assembled to a step portion provided in the bore hole.

Japanese Patent Laying-Open No. 2015-25361

  By the way, in the conventional piston pump, the stepped portion of the housing that accommodates and supports the guide member while being spaced apart from the cam chamber that accommodates the eccentric cam is provided at right angles to the axis of the piston. In this case, a load acting in a direction along the axis via the guide ring (guide member) when the piston swings (swings) with respect to the axis is input to the step portion in a so-called cantilever state. Therefore, the distance between the cam chamber and the guide member, that is, the plate thickness in the direction along the axis of the stepped portion must be set large to ensure the strength of the housing. Therefore, in the conventional piston pump, from the viewpoint of securing the strength of the housing, the so-called pump shaft length may be increased, and it may be difficult to realize a reduction in size and weight.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a piston pump that can be reduced in size and weight while ensuring the strength of the housing.

  In order to solve the above-described problem, a piston pump according to claim 1 includes a housing, a cylinder member accommodated in an accommodation hole provided in the housing, and a piston that is inserted into the cylinder member and reciprocates within the accommodation hole. A drive mechanism housing chamber that is provided in the housing and communicates with the housing hole and houses a drive mechanism for driving the piston, and a drive mechanism between the inner peripheral surface of the housing hole and the outer peripheral surface of the piston than the cylinder member The seal member disposed on the storage chamber side, and disposed between the inner peripheral surface of the storage hole and the outer peripheral surface of the piston on the drive mechanism storage chamber side with respect to the seal member, and in the radial direction perpendicular to the axis of the piston And a guide member that regulates displacement, wherein the inner peripheral surface of the accommodation hole is directed from the first inner diameter to the second inner diameter smaller than the first inner diameter in a direction along the axis toward the drive mechanism accommodation chamber. The And diameter, having a restricting surface for restricting the movement of the drive mechanism housing chamber side of the guide member.

  According to this, when the piston is displaced in the radial direction, that is, when the piston swings, the guide member transmits a load accompanying the swinging of the piston to the restriction surface constituting the housing hole of the housing. Since the regulating surface is provided so as to reduce the diameter toward the drive mechanism accommodation chamber in the direction along the axis from the first inner diameter to the second inner diameter, the transmitted load is in the radial direction and the direction along the axis. And can be dispersed. Accordingly, in particular, the load in the direction along the axis is smaller than that in the case where the step is provided at a right angle to the axis, so that the load in the direction along the axis in the portion including the regulating surface that supports the guide member is reduced. Even if the plate thickness is not increased, the strength of the housing can be sufficiently ensured. Therefore, it is not necessary to secure the strength of the housing by increasing the plate thickness in the portion supporting the guide member, particularly in the direction along the axis, and as a result, the pump shaft length can be shortened and miniaturized. Can be realized, and weight reduction can be realized.

It is the schematic which shows the structure of the piston pump which concerns on embodiment of this invention. It is sectional drawing for demonstrating the control surface in the accommodation hole provided in the housing of FIG. It is sectional drawing for demonstrating the structure of the guide member of FIG. It is sectional drawing for demonstrating the relationship of the load transmitted to a control surface from a guide member. It is sectional drawing for demonstrating the control surface which concerns on the 1st modification of embodiment. It is sectional drawing for demonstrating the structure of the guide member which concerns on the 1st modification of embodiment. It is sectional drawing for demonstrating the control surface which concerns on the 2nd modification of embodiment. It is sectional drawing for demonstrating the structure of the guide member which concerns on the 2nd modification of embodiment. It is sectional drawing for demonstrating the structure of the guide member which concerns on the other modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments and modifications, the same or equivalent parts are denoted by the same reference numerals in the drawings. Each figure used for explanation is a conceptual diagram, and the shape of each part may not necessarily be exact.

  As shown in FIG. 1, the piston pump 100 includes a first cylinder member 103 and a second cylinder member 104 that are liquid-tightly accommodated in an accommodation hole 102 provided in the housing 101. A piston 105 and a suction valve 106 are disposed inside the two-cylinder member 104. As shown in FIG. 2, the housing hole 102 includes a first inner peripheral surface 102a having a first inner diameter d1, a second inner peripheral surface 102b having a second inner diameter d2 smaller than the first inner diameter d1, The inner peripheral surface 102a and the second inner peripheral surface 102b are connected to each other, and a regulation slope 102c is provided as a regulation surface that comes into contact with a guide member 119 described later. In the present embodiment, the regulation slope 102c is formed so as to have a so-called mortar shape so as to continuously reduce the diameter from the first inner diameter d1 toward the second inner diameter d2.

  The first cylinder member 103 and the second cylinder member 104 are accommodated so as to be fitted to the first inner peripheral surface 102 a of the accommodation hole 102. The first cylinder member 103 and the second cylinder member 104 are connected to each other while being accommodated in the accommodation hole 102 (first inner peripheral surface 102a), and the piston 105 and the suction valve 106 are allowed to slide.

  The piston 105 is accommodated with respect to the first cylinder member 103 and the second cylinder member 104 so that one end side faces a pump chamber 108 to be described later, and serves as a drive mechanism accommodation chamber provided in the housing 101 on the other end side. The cam chamber 107a is driven by an eccentric cam 107 as a drive mechanism accommodated rotatably. The other end of the piston 105 is in sliding contact with the cam surface of the eccentric cam 107 that is rotated by the rotational driving force of a motor (not shown) that drives the piston pump 100, and in the direction of the axis by the rotation of the eccentric cam 107. It is pushed along and reciprocates.

  The suction valve 106 has a proximal end connected to the other end of the piston 105. The tip of the suction valve 106 is disposed in a pump chamber 108 provided inside the first cylinder member 103. The suction valve 106 moves along the axial direction together with the piston 105 by the rotation of the eccentric cam 107 to pressurize a fluid (for example, brake fluid) inside the pump chamber 108, and then apply the fluid into the pump chamber 108. Inhaled.

  The piston pump 100 includes a discharge valve 109, a discharge port 110, a return spring 111, a suction port 112, and an auxiliary piston 113. The discharge valve 109 discharges the fluid pressurized in the pump chamber 108 to the discharge port 110. The discharge port 110 is connected to a device (for example, a vehicle brake system not shown) through a pipe (not shown). Thereby, the high-pressure fluid discharged from the discharge port 110 is supplied to the device.

  The return spring 111 applies an elastic force (return force) to the piston 105 that is pressed by the cam surface of the eccentric cam 107 and moves along the direction of the axis. The suction port 112 sucks fluid from a reservoir (not shown) into the inside of the housing 101, more specifically, into a feed chamber 114 formed by the second cylinder member 104 and the piston 105.

  The auxiliary piston 113 sucks fluid into the feed chamber 114 when the piston 105 is in a compression process in which the fluid inside the pump chamber 108 is compressed. Further, the auxiliary piston 113 sends the fluid in the feed chamber 114 toward the pump chamber 108 when the piston 105 is in the suction process of sucking fluid into the pump chamber 108. The auxiliary piston 113 is provided to give the piston pump 100 a self-priming function, and may be omitted as necessary.

  In the piston pump 100, an annular seal member 115 is provided between the first inner peripheral surface 102 a in the housing hole 102 of the housing 101 and the outer peripheral surface 105 a of the piston 105. The seal member 115 includes an O-ring 116 made of an elastic material (for example, rubber material), a sliding ring 117 made of a resin material (for example, fluorine resin), and a backup ring 118.

  The sliding ring 117 is interposed between the outer peripheral surface 105a of the piston 105 and the O-ring 116, and the sliding surface 117a (inner diameter side in the present embodiment) of the sliding ring 117 is slid (in this embodiment). In the embodiment, sliding wear of the O-ring 116 is prevented by contacting the outer peripheral surface 105a) of the piston 105. The backup ring 118 is disposed on the cam chamber 107a side with respect to the seal member 115, prevents deformation in the direction along the axis of the O-ring 116, and directly contacts the guide member 119 and the O-ring 116. To prevent it. Here, the outer diameter of the backup ring 118 is set smaller than the first inner diameter d1 of the first inner peripheral surface 102a.

  Further, in the piston pump 100 of this embodiment, the eccentric cam which is between the first inner peripheral surface 102a and the regulating inclined surface 102c in the housing hole 102 of the housing 101 and the outer peripheral surface 105a of the piston 105 and is a drive mechanism. An annular guide member 119 disposed between a cam chamber 107 a serving as a drive mechanism housing chamber for housing 107 and a backup ring 118 of the seal member 115 is provided. The guide member 119 restricts at least the displacement in the radial direction orthogonal to the axis line of the piston 105 driven by the rotating eccentric cam 107, that is, swinging, by contacting with the restricting slope 102c.

  As shown in FIG. 2, the guide member 119 is formed so that the cross-sectional shape in a plane including the axis is a polygon, specifically, a pentagon. For this reason, the guide member 119 extends in the radial direction in the state of being accommodated in the accommodation hole 102 and is opposed to the seal member 115 (more specifically, the backup ring 118 in the present embodiment). And a second surface 119b extending in parallel with the first surface 119a and disposed on the cam chamber 107a (eccentric cam 107) side. Here, the outer diameter of the second surface 119b is set to be smaller than the outer diameter of the first surface 119a.

  The guide member 119 extends in the direction along the axis on the inner peripheral side in the state of being accommodated in the accommodation hole 102, faces the piston 105, and has the first surface 119 a and the second surface 119 b. A third surface 119c to be connected, and a fourth surface 119d that extends in parallel with the third surface 119c on the outer peripheral side, contacts the first inner peripheral surface 102a, and is connected to the first surface 119a. Have. Further, the guide member 119 connects the second surface 119b and the fourth surface 119d in the state of being accommodated in the accommodation hole 102, and is a contact slope as a contact surface that comes into contact with the regulation slope 102c of the storage hole 102. 119e. The contact slope 119e is formed so as to coincide with a cross-sectional shape in a plane including the axis of the regulation slope 102c, specifically, in the present embodiment, an inclination (inclination) in a direction along the axis.

  Here, the guide member 119 is formed by injection molding using a thermoplastic resin such as polypropylene as a material. For this reason, the guide member 119 has a convex or concave gate mark 119f on the second surface 119b, which leaves the shape of the resin introduction gate of the injection mold as the concave and convex portion. That is, in the guide member 119, the gate mark 119f is provided on the second surface 119b, in other words, on the side of the eccentric cam 107 as an uneven portion.

  In the piston pump 100 configured as described above, the swinging generated in the radial direction of the piston 105 with the rotation of the eccentric cam 107 is regulated by the guide member 119. In this case, the guide member 119 transmits the load input with the swing of the piston 105 to the regulation slope 102c that forms the housing hole 102 of the housing 101 via the contact slope 119e as shown in FIG. To do. Here, the load accompanying the swing is input as the load Fn perpendicular to the regulating slope 102c, and the load Fn is distributed to the load component Fj in the direction along the axis and the load component Fk in the radial direction and acts on the housing 101. To do. As a result, for example, when the regulation slope 102c is provided as compared with the case where the step portion is provided so as to be perpendicular to the direction of the axis as in the conventional piston pump described above, the direction along the axis is particularly preferred. Load component Fj is reduced. In this case, the radial load component Fk is also reduced by the regulation slope 102c.

  As can be understood from the above description, the piston pump 100 of the above embodiment includes the housing 101 and the first cylinder member 103 and the second cylinder member which are cylinder members accommodated in the accommodation hole 102 provided in the housing 101. 104, a piston 105 inserted into the first cylinder member 103 and the second cylinder member 104 and reciprocatingly moved inside the accommodation hole 102, and provided in the housing 101, and communicates with the accommodation hole 102 to drive the piston 105. A first cylinder is provided between a cam chamber 107 a serving as a drive mechanism housing chamber that houses an eccentric cam 107 serving as a drive mechanism, and a first inner circumferential surface 102 a that is an inner circumferential surface of the housing hole 102 and an outer circumferential surface 105 a of the piston 105. More eccentric cam chamber 107a than second cylinder member 104 of member 103 and second cylinder member 104. The seal member 115 (O-ring 116) disposed between the first inner peripheral surface 102a and the outer peripheral surface 105a of the piston 105, and the seal member 115 (O-ring 116). A piston pump that is disposed on the side of the eccentric cam chamber 107a and restricts displacement in the radial direction perpendicular to the axis of the piston 105, and the inner peripheral surface of the accommodation hole 102 has a first inner diameter As a regulating surface for reducing the diameter of the guide member 119 toward the eccentric cam chamber 107a in the direction along the axis from d1 to the second inner diameter d2 smaller than the first inner diameter d1, It has a regulation slope 102c.

  According to this, when the piston 105 is displaced in the radial direction, that is, when the so-called piston 105 swings, the guide member 119 moves against the regulation slope 102 c as a regulation surface constituting the accommodation hole 102 of the housing 101. A load Fn accompanying the swing of 105 is transmitted. Since the regulating slope 102c is provided so as to decrease in diameter from the first inner diameter d1 toward the second inner diameter d2, that is, to have a certain inclination along the direction of the axis, the transmitted load Fn is reduced. The load component Fj in the direction along the axis and the load component Fk in the radial direction can be dispersed.

  Thereby, in particular, the load component Fj in the direction along the axis is reduced by the regulating slope 102c as compared with the case where the step is provided at right angles to the axis as in the prior art, so the guide member 119 is supported. The strength of the housing 101 can be sufficiently ensured without increasing the plate thickness in the direction along the axis in the portion including the regulating slope 102c. Accordingly, it is not necessary to secure the strength of the housing 101 by increasing the plate thickness in the portion supporting the guide member 119, particularly in the direction along the axis, and as a result, in the piston pump 100, the pump shaft length It is possible to reduce the size by shortening the length, and it is possible to reduce the weight.

  In this case, the guide member 119 has a contact slope 119e as a contact surface that is reduced in diameter so as to contact the regulation slope 102c in a state of being accommodated in the accommodation hole 102. In this case, the guide slope 119e The cross-sectional shape in the plane including the axis coincides with the cross-sectional shape in the plane of the regulation slope 102c.

  According to this, when the piston 105 swings, the guide member 119 can transmit the load Fn to the regulation slope 102c via the contact slope 119e. Then, by matching the cross-sectional shapes of the contact slope 119e and the regulation slope 102c, the contact area between the contact slope 119e and the regulation slope 102c can be increased, and as a result, the load Fn per unit area. The surface pressure representing the size of can be reduced.

  Also by this, the strength of the housing 101 can be sufficiently ensured without increasing the plate thickness in the direction along the axis in the portion including the regulating slope 102c that supports the guide member 119. Therefore, it is not necessary to ensure the strength of the housing 101 by increasing the plate thickness at the portion including the regulating slope 102c. As a result, the piston pump 100 can be reduced in size by reducing the pump shaft length. And weight reduction is realizable.

  Further, in these cases, the guide member 119 is made of resin (for example, made of thermoplastic resin such as polypropylene), and is a surface on the side of the eccentric cam 107 and is a side away from the seal member 115 (O-ring 116). The second surface 119b has a gate mark 119f as a convex or concave concavo-convex portion.

  According to this, since the guide member 119 can be made of resin, for example, the sliding friction generated between the third surface 119c (the inner peripheral surface) of the guide member 119 and the outer peripheral surface 105a of the piston 105 is reduced. It can be greatly reduced.

  Further, the gate mark 119f generated when the resin guide member 119 is molded can be provided on the eccentric cam 107 side, that is, on the second surface 119b on the side away from the seal member 115 (O-ring 116). Thereby, for example, even if the gate mark 119f is not removed separately, the possibility of damaging the seal member 115 (O-ring 116) is significantly reduced by providing the gate mark 119f on the second surface 119b. Can do.

  Here, the guide member 119 is asymmetric with respect to the radial direction in the direction along the axis by having the contact slope 119e. Thereby, when assembling the guide member 119 with respect to the accommodation hole 102, the assembling operator can grasp the normal insertion direction of the guide member 119 very easily. Thereby, for example, the possibility of erroneous assembly in which the second surface 119b is assembled toward the seal member 115 (O-ring 116) can be reduced, and the smooth first surface 119a becomes the seal member 115 (O-ring). 116), the guide member 119 can be assembled in a normal assembled state facing the side of 116).

(First modification)
In the above embodiment, the restricting surface that forms the accommodation hole 102 of the housing 101 and abuts against the guide member 119 continuously from the first inner diameter d1 to the second inner diameter d2, that is, along the direction of the axis. A regulation slope 102c is provided to reduce the diameter with a certain inclination and connect the first inner peripheral surface 102a and the second inner peripheral surface 102b. In addition to this, for example, as shown in FIG. 5, in a part of the regulation slope 102 c that is a regulation surface that continuously shrinks from the first inner diameter d <b> 1 toward the second inner diameter d <b> 2 and contacts the guide member 119. It is also possible to provide a concave step portion 102d so as to reduce the diameter stepwise. In FIG. 5, one stepped portion 102d having a reduced diameter is provided in part of the regulating slope 102c, but a plurality of stepped portions 102d may be provided in part of the regulating slope 102c. is there.

  In this first modified example, as shown in FIG. 6, the guide member 119 is provided with a convex portion 119g on the contact slope 119e so as to engage with the step portion 102d of the accommodation hole 102. By providing the projection 119g on the guide member 119 in this manner, positioning when the guide member 119 is assembled to the accommodation hole 102 (housing 101) is facilitated, and the assembling workability can be improved. Further, by providing the guide member 119 with the convex portion 119g, the displacement of the guide member 119 can be suppressed when the piston 105 swings. As a result, the piston 105 can be appropriately moved in the direction along the axis. Can be guided to. In the first modified example, the stepped portion 102d is provided in a concave shape on the regulating slope 102c, but the stepped portion 102d may be provided in a convex shape. In this case, the guide member 119 can be provided with a recess in accordance with the stepped portion 102d.

(Second modification)
In the above-described embodiment, the regulation slope 102c as the regulation surface forming the accommodation hole 102 has a certain inclination and is reduced in diameter. In other words, the regulation slope 102c in a plane including the axis is formed to have a straight cross section as shown in FIG. Instead, for example, as shown in FIG. 7, as a regulating surface for forming the accommodation hole 102, in a plane including the axis line so as to continuously reduce the diameter from the first inner diameter d <b> 1 toward the second inner diameter d <b> 2. It is also possible to form a regulation curved surface 102e having a curved cross-sectional shape.

  In the second modification, as shown in FIG. 8, the guide member 119 is provided with a contact slope 119h formed so as to match the shape (curve) of the regulation curved surface 102e. Thus, by providing the guide member 119 with the contact slope 119h that coincides with the regulation curved surface 102e, the displacement of the guide member 119 can be suppressed when the piston 105 swings. Similarly, the movement of the piston 105 in the direction along the axis can be appropriately guided.

  In carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, the fourth surface 119d is in contact with the first inner peripheral surface 102a of the accommodation hole 102 and the guide member 119 is connected to the contact slope 119e. Alternatively, for example, as shown in FIG. 9, the fourth surface 119d may be omitted and the cross-sectional shape may be a quadrangle. In this case, since the size of the fourth surface 119d in the direction along the axis of the guide member 119 can be shortened by the formation dimension, the size of the direction along the axis of the housing 101 can be further shortened. Therefore, further downsizing of the piston pump 100 can be achieved.

  In the embodiment and the modification, the backup ring 118 is provided between the seal member 115 and the guide member 119. By the way, in the guide member 119, the gate trace 119f as an uneven | corrugated | grooved part exists in the 2nd surface 119b which is a surface on the opposite side to the 1st surface 119a which is a surface facing the seal member 115. FIG. That is, in the guide member 119, the first surface 119a is smooth, and even if it contacts the O-ring 116 of the seal member 115, there is little possibility of damaging the O-ring 116, and the O-ring 116 is not deformed. Can be suppressed. Therefore, the piston pump 100 can be configured by omitting the backup ring 118. In this case, the size in the direction along the axis of the housing 101 (accommodating hole 102) can be shortened by the formation dimension of the backup ring 118, and further downsizing of the piston pump 100 can be achieved. Can do.

  In the embodiment and the modified example, the thickness of the guide member 119 is uniform over the entire circumference. Instead, the guide member 119 can perform so-called meat stealing (thickening) in which the thickness is continuously or discontinuously reduced in the circumferential direction. Thereby, the weight reduction of the guide member 119 is attained, and the weight reduction of the piston pump 100 can be achieved by extension.

  Further, in the above embodiment and the above modification, the guide member 119 is assumed to be annular. Instead of this, the guide member 119 can be provided discontinuously along the circumferential direction, for example.

DESCRIPTION OF SYMBOLS 100 ... Piston pump, 101 ... Housing, 102 ... Accommodating hole, 102a ... 1st inner peripheral surface, 102b ... Second inner peripheral surface, 102c ... Restriction slope (regulation surface), 102d ... Step part (regulation surface), 102e ... Restricted curved surface (restricted surface), 103 ... first cylinder member, 104 ... second cylinder member, 105 ... piston, 105a ... outer peripheral surface, 106 ... suction valve, 107 ... eccentric cam (drive mechanism), 107a ... cam chamber (drive) Mechanism housing chamber), 108 ... pump chamber, 109 ... discharge valve, 110 ... discharge port, 111 ... return spring, 112 ... suction port, 113 ... auxiliary piston, 114 ... feed chamber, 115 ... seal member, 116 ... O-ring, 117 ... sliding ring, 117a ... sliding surface, 118 ... backup ring, 119 ... guide member, 119a ... first surface, 119b ... second surface (on the side of the eccentric cam) 119c ... third surface, 119d ... fourth surface, 119e ... contact slope (contact surface), 119f ... gate mark (uneven portion), 119g ... convex portion (contact surface), 119h ... contact slope ( Abutment surface), d1 ... first inner diameter, d2 ... second inner diameter, Fj ... load component (direction of axis), Fk ... load component (radial direction)

Claims (6)

A housing;
A cylinder member accommodated in an accommodation hole provided in the housing;
A piston that is inserted into the cylinder member and reciprocates within the accommodation hole;
A drive mechanism accommodation chamber that is provided in the housing and accommodates a drive mechanism that communicates with the accommodation hole and drives the piston;
A seal member disposed between the inner circumferential surface of the housing hole and the outer circumferential surface of the piston, closer to the drive mechanism housing chamber than the cylinder member;
Between the inner peripheral surface of the receiving hole and the outer peripheral surface of the piston, it is disposed closer to the drive mechanism receiving chamber than the seal member, and restricts displacement of the piston in the radial direction perpendicular to the axis. A piston pump comprising: a guide member that includes:
The inner peripheral surface of the accommodation hole is
From the first inner diameter to the second inner diameter smaller than the first inner diameter, the diameter is reduced toward the drive mechanism accommodation chamber in the direction along the axis, and the movement of the guide member toward the drive mechanism accommodation chamber is restricted. A piston pump with a regulating surface. Part of the regulatory surface is
The piston pump according to claim 1, wherein the diameter is gradually reduced from the first inner diameter toward the second inner diameter. The guide member is
3. The piston pump according to claim 1, wherein the piston pump has a contact surface that is reduced in diameter so as to contact the restriction surface in a state of being stored in the storage hole. The cross-sectional shape in a plane including the axis of the contact surface is:
The piston pump according to claim 3, wherein the piston pump matches a cross-sectional shape in the plane of the restriction surface.   The piston pump according to any one of claims 1 to 4, wherein the guide member is made of resin. The guide member is
The piston pump according to claim 5, wherein the eccentric cam has a convex or concave uneven portion on a surface thereof.

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