Abstract: A pump includes: fluid delivery portions each including a volume variable mechanism, a first port and a second port, and a valve mechanism; and a pump flow path formed by the three or more fluid delivery portions being connected in series, in which a movement range of each of pistons includes a maximum volume position, a minimum volume position, and a switching position, and the pump flow path is configured such that a closing movement process (movement between switching position and minimum volume position) in which the piston moves between the switching position and the minimum volume position by driving of a drive device is sequentially shifted from a first inlet/outlet port toward a second inlet/outlet port or from the second inlet/outlet port toward the first inlet/outlet port among the fluid delivery portions

Abstract: In a piston pump, for example, a piston sub assembly includes a columnar plunger that lies along an axial direction, a cap that is fixed with the plunger to cover an adjacent region between a first end surface at one end in the axial direction of the plunger and the first end surface at a first outer circumferential surface of the plunger, and provided with an intake passage extending from an inlet on an outer side of the first outer circumferential surface to an outlet on an outer side of the first end surface outside the plunger, and a first valve seat of a first intake check valve located at the outlet, and a seal member that is a member different from the cap and that prevents leakage of hydraulic fluid from the first chamber through a gap between the first cylinder and the piston sub assembly.

Abstract: A pump includes a fluid outflow mechanism that causes the brake fluid in the discharge chamber to flow out into the suction chamber in accordance with decrease in the volume of the discharge chamber when the feed ring of the valve portion decreases the volume of the discharge chamber in cooperation with the increasing movement of the volume of the first pump chamber in a state where the first pump chamber and the discharge chamber are filled with brake fluid in the suction step.

Abstract: In a piston pump, for example, a piston sub assembly includes a columnar plunger that lies along an axial direction, a cap that is fixed with the plunger to cover an adjacent region between a first end surface at one end in the axial direction of the plunger and the first end surface at a first outer circumferential surface of the plunger, and provided with an intake passage extending from an inlet on an outer side of the first outer circumferential surface to an outlet on an outer side of the first end surface outside the plunger, and a first valve seat of a first intake check valve located at the outlet, and a seal member that is a member different from the cap and that prevents leakage of hydraulic fluid from the first chamber through a gap between the first cylinder and the piston sub assembly.

Abstract: In the present invention, when a first protrusion of a shaft abuts on a guide face thereby pressing a first valve element toward the top as seen in the drawing, the guide face is separated from a cylinder seat face, and a large-diameter oil passage is opened. At this time, when the first protrusion abuts on the guide face thereby driving the first valve element to the position where the valve opens, the first valve element is also pressed in a direction perpendicular to the reciprocating direction of the first valve element because the guide face has a spherical surface or a tapered surface. Thus, the first valve element is supported at two points, point E and point F or G, thereby dampening vibrations.

Abstract: In the present invention, when a first protrusion of a shaft abuts on a guide face thereby pressing a first valve element toward the top as seen in the drawing, the guide face is separated from a cylinder seat face, and a large-diameter oil passage is opened. At this time, when the first protrusion abuts on the guide face thereby driving the first valve element to the position where the valve opens, the first valve element is also pressed in a direction perpendicular to the reciprocating direction of the first valve element because the guide face has a spherical surface or a tapered surface. Thus, the first valve element is supported at two points, point E and point F or G, thereby dampening vibrations.

Abstract: A pressure control reservoir includes a valve ball and a shaft which is movable to move the valve ball to open or close a fluid path leading to a fluid reservoir chamber. The shaft has a tip with a slant surface which has a peripheral edge of a polygonal shape with even numbers of vertices and is inclined to the longitudinal center line of the shaft. Such a polygonal geometry increases an entire or inclined length of the slant surface, which results in an increased range where an angle which the slant surface makes with a plane extending perpendicular to an axial direction of the tip is permitted to be increased without causing the point of contact between the valve ball and the slant surface to be shifted close to the tip of the slant surface when the tip of the shaft moves the valve ball.

Abstract: A brake fluid pressure control device includes: a electromagnetic control valve; a electromagnetic booster valve; a electromagnetic decompression valve; a pump, which are incorporated in a single housing; and an electronic control unit, wherein, the pump draws up at least one of brake fluid, which is supplied from the main reservoir, and brake fluid, which is discharged from the wheel cylinder, and then the pump returns the drawn brake fluid to an area that extends from the electromagnetic control valve of a main flow path up to the electromagnetic booster valve; and a fluid reservoir, which communicates with both the decompression path and an intake port of the pump, and which is arranged inside the housing so that the brake fluid in the fluid reservoir flows toward the intake port of the pump by gravity.

Abstract: A pressure control reservoir includes a valve ball and a shaft which is movable to move the valve ball to open or close a fluid path leading to a fluid reservoir chamber. The shaft has a tip with a slant surface which has a peripheral edge of a polygonal shape with even numbers of vertices and is inclined to the longitudinal center line of the shaft. Such a polygonal geometry increases an entire or inclined length of the slant surface, which results in an increased range where an angle which the slant surface makes with a plane extending perpendicular to an axial direction of the tip is permitted to be increased without causing the point of contact between the valve ball and the slant surface to be shifted close to the tip of the slant surface when the tip of the shaft moves the valve ball.

Abstract: A sealing structure is provided wherein an annular groove formed in a pump cylinder of a piston pump receives therein a seal ring made of a synthetic resin material and having an inner circumferential surface fluid-tightly contacting an outer circumferential surface of the pump piston and an O-ring arranged on the outer circumferential side of the seal ring and urging the seal ring radially inward. The seal ring is formed at its axial end portions with flange portions for preventing the O-ring from coming off. In the state that the seal ring and the O-ring are fitted in the annular groove, the flange portions do not receive a load from the O-ring, and a surface pressure which the seal ring applies to the outer circumferential surface of the piston at an axial center portion thereof is set to be higher than surface pressures which it applies to the outer circumferential surface of the piston at axial end portions thereof.

Abstract: A piston pump includes a pump mechanism configured to compress fluid sucked from an inlet port by increasing or decreasing a volume of a pump chamber which faces a front end of a piston by reciprocating the piston housed in a housing, a feed mechanism including a feed ring mounted to an annular groove provided at an outer periphery of the piston and following a motion of the piston, a feed chamber formed between the feed ring and the housing, and a valve portion. The piston pump includes a pressure wall provided at the piston and configured to contact the feed ring to axially move the feed ring, and a restriction portion provided at the feed ring and configured to engage with an outer periphery of the piston at a position approximate to the pressure wall for restricting a radial displacement of the feed ring on the piston.

Abstract: A piston pump assembly includes a first pump having a first cylinder member inserted in a piston hole of a pump housing, and a first piston inserted in the first cylinder member, and a second pump having a second cylinder member inserted in the piston hole, and an annular second piston slidably fitted in an annular groove formed in the outer periphery of the first piston, and also axially slidably inserted in the second cylinder member. The first cylinder member axially presses the second cylinder member, thereby preventing the second cylinder member from being dropped out of the piston hole. The second cylinder member has an annular seal surface in contact with a shoulder surface formed on the inner periphery of the piston hole. Strain-absorbing protrusions are formed on the end of the second cylinder member in abutment with the first cylinder member. The protrusions are compressed when they are pressed by the first cylinder member.

Abstract: A brake fluid pressure control device includes: a electromagnetic control valve; a electromagnetic booster valve; a electromagnetic decompression valve; a pump, which are incorporated in a single housing; and an electronic control unit, wherein, the pump draws up at least one of brake fluid, which is supplied from the main reservoir, and brake fluid, which is discharged from the wheel cylinder, and then the pump returns the drawn brake fluid to an area that extends from the electromagnetic control valve of a main flow path up to the electromagnetic booster valve; and a fluid reservoir, which communicates with both the decompression path and an intake port of the pump, and which is arranged inside the housing so that the brake fluid in the fluid reservoir flows toward the intake port of the pump by gravity.

Abstract: A pressure regulating reservoir includes, first and second conduits, a reservoir chamber, first and second reservoir ports, a valve portion including a first hydraulic passage, first and second valve bodies, and a valve seat including a second hydraulic passage, a piston portion including a piston and a spring, a mobile member, a protruding portion and a shaft, wherein the first hydraulic passage is closed by the second valve body thereby interrupting the fluid communication when the pump is not actuated, a pressure difference between a brake hydraulic pressure within the reservoir chamber and a brake hydraulic pressure within the first reservoir port is regulated when the pump is actuated while the brake hydraulic pressure is generated by the brake hydraulic pressure generating means, and the second hydraulic passage is opened to establish the fluid communication when the pump is actuated while no brake hydraulic pressure is generated.

Abstract: A filter to be mounted in a valve seat member for filtering liquid is proposed which can be manufactured without a drawing step, thereby improving productivity and cost performance of a piston pump in which such a filter is mounted. The filter is a flat metal plate including a main body formed with a plurality of filter holes in a central portion thereof, and a plurality of projections integrally and radially outwardly extending from a perimeter of the main body so as to be circumferentially spaced apart from each other. The filter is pushed into a filter mounting hole formed in a valve seat member of a discharge valve in a piston pump with the projections bent toward the opening of the filter mounting hole while being pressed against the inner surface of the filter mounting hole under an elastic restoring force and fixed to the valve seat member.

Abstract: A piston pump includes a pump mechanism for changing a volume of a pump chamber to move a piston in a housing, and a feed mechanism that has a feed ring attached to a circular groove portion of the piston to be slaved with a movement of the piston. The feed mechanism is located in a suction passage from a suction port to a pump chamber, and the piston has a flange portion protruding radially outwardly. An inner peripheral surface of the feed ring has an inner-diameter enlarged portion extending radially outwardly to have an enlarged passage portion between the inner peripheral surface of the feed ring and the outer peripheral surface of the piston, and a valve portion for opening and closing a suction passage is constructed of an end portion of the inner diameter enlarged portion of the feed ring and the flange portion.

Abstract: A sealing structure is provided wherein an annular groove formed in a pump cylinder of a piston pump receives therein a seal ring made of a synthetic resin material and having an inner circumferential surface fluid-tightly contacting an outer circumferential surface of the pump piston and an O-ring arranged on the outer circumferential side of the seal ring and urging the seal ring radially inward. The seal ring is formed at its axial end portions with flange portions for preventing the O-ring from coming off. In the state that the seal ring and the O-ring are fitted in the annular groove, the flange portions do not receive a load from the O-ring, and a surface pressure which the seal ring applies to the outer circumferential surface of the piston at an axial center portion thereof is set to be higher than surface pressures which it applies to the outer circumferential surface of the piston at axial end portions thereof.

Abstract: A piston pump assembly includes a first pump having a first cylinder member inserted in a piston hole of a pump housing, and a first piston inserted in the first cylinder member, and a second pump having a second cylinder member inserted in the piston hole, and an annular second piston slidably fitted in an annular groove formed in the outer periphery of the first piston, and also axially slidably inserted in the second cylinder member. The first cylinder member axially presses the second cylinder member, thereby preventing the second cylinder member from being dropped out of the piston hole. The second cylinder member has an annular seal surface in contact with a shoulder surface formed on the inner periphery of the piston hole. Strain-absorbing protrusions are formed on the end of the second cylinder member in abutment with the first cylinder member. The protrusions are compressed when they are pressed by the first cylinder member.

Abstract: A piston pump includes a pump housing having a suction port and a discharge port. A piston is mounted in a bore of the pump housing and forms a pump chamber. Suction and discharge valves are provided on the opposite sides of the pump chamber, respectively. The suction valve includes a retainer which is mounted on the piston and has a valve bore which communicates with the suction port, a valve seat which is formed at the pump chamber end of the valve bore, and a valve body holding portion and a spring holding portion. The suction valve also includes a valve body which can seat and unseat from the valve seat and which is received and held by the valve body holding portion, and a spring which is received and held by the spring holding portion and biases the valve body towards the valve seat.

Abstract: A piston pump includes a pump mechanism configured to compress fluid sucked from an inlet port by increasing or decreasing a volume of a pump chamber which faces a front end of a piston by reciprocating the piston housed in a housing, a feed mechanism including a feed ring mounted to an annular groove provided at an outer periphery of the piston and following a motion of the piston, a feed chamber formed between the feed ring and the housing, and a valve portion. The piston pump includes a pressure wall provided at the piston and configured to contact the feed ring to axially move the feed ring, and a restriction portion provided at the feed ring and configured to engage with an outer periphery of the piston at a position approximate to the pressure wall for restricting a radial displacement of the feed ring on the piston.