JP2007170319A - Piston pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston pump performing discharge twice per one reciprocating stroke of a piston, and continuously operated to reduce pulse pressure of discharge pressure. <P>SOLUTION: The piston pump 1 is constituted of a pump housing 1 having a cylinder housing chamber 4 connected with a suction port 7 and a discharge port 8, and the piston 6 slidably housed in the cylinder chamber and axiliary reciprocated. The cylinder chamber 4 has: a first pressure chamber 11 which is partitioned and formed by the piston, is connected with the suction port, and is disposed to a piston bottom side; and a second pressure chamber 12 which is formed to an outer periphery on a tip side of the piston, and is connected with the discharge port. A communicating passage 15 connecting the first pressure chamber with the second pressure chamber is formed in the piston. The volume of the second pressure chamber is set to be smaller than that of the first pressure chamber, and the capacity of the second pressure chamber is decreased in maximum proceeding of the piston, with leaving a predetermined volume space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piston pump that is applied to a brake hydraulic pressure control device for a vehicle that controls hydraulic pressure, such as an anti-lock brake control device (ABS). It is related with the piston pump which can reduce the pulse pressure at the time of discharge by discharging.

  As a conventional piston pump, what was described in the following patent document 1, for example is proposed.

  The piston pump includes a pump casing having an inflow hole and an outflow hole and cylinder holes connected to the holes, a pump piston provided in the cylinder hole so as to be slidable in an axial direction, and the pump piston as a shaft. And an outlet valve (check valve) that allows flow from the cylinder chamber to the outflow hole.

  The pump piston has a stepped columnar shape and is formed to have a reduced diameter at the tip, and a plurality of lateral holes are formed through the tip in a direction perpendicular to the axis and communicated with the inflow hole through the cylinder hole. In addition, in the axial direction, a bag hole that is connected to the lateral hole and opens on the rear end side of the pump piston is provided, and an inlet that allows only flow from the front end side to the rear end side inside the bag hole. A valve (check valve) is arranged.

  The cylinder hole is divided by the pump piston into two chambers, a first cylinder chamber that communicates the inflow hole and the lateral hole, and a second cylinder chamber that communicates the bag hole and the outflow hole. As the pump piston reciprocates, the volume of each cylinder chamber alternately repeats expansion and contraction.

As a result, when the pump piston advances, the hydraulic oil flows into each side hole through the first cylinder chamber, and also flows into the second cylinder chamber having an enlarged volume through the bag hole. When retreating, the piston is compressed by the rear end portion of the piston and discharged from the outflow hole.
JP 2002-536580 A

  However, since the piston pump has a structure in which the pump piston discharges once per reciprocating process of the pump piston as described above, the discharge action of the hydraulic oil becomes intermittent.

  Thereby, the pulse pressure at the time of discharge becomes large, and there is a problem that the discharge pressure at the time of high speed operation of the pump is not stable.

  The present invention has been devised by paying attention to such a technical problem. The discharge is performed twice per one reciprocation process of the piston, and the pump can be continuously operated. A piston pump capable of reducing pressure is provided.

  According to a first aspect of the present invention, there is provided a pump housing having a suction port and a discharge port, and a cylinder chamber communicated with the suction port and the discharge port. A piston driven by a source and performing a pumping action by reciprocating in the axial direction; a first check valve that allows only flow from the suction port to the cylinder chamber; and from the cylinder chamber to the discharge port A first check valve that allows only the flow of the gas, a first pressure chamber that communicates with the suction port and that is separated by the piston, and communicates with the discharge port. A second pressure chamber whose volume changes relative to the pressure chamber; a communication passage for communicating the first pressure chamber and the second pressure chamber; and the first pressure chamber disposed in the communication passage. A third check valve that allows only the flow from the first pressure chamber to the second pressure chamber side, and the first pressure chamber is formed on the bottom side of the piston, while the second pressure chamber is formed on the cylinder By forming the front end side outer periphery of the piston passing through the chamber in the axial direction, the volume is set to be smaller than that of the first pressure chamber, and when the piston is advanced to the maximum, the second pressure chamber has a predetermined volume space. It is characterized by being configured to reduce the size of the image.

  According to this invention, the volume of the second pressure chamber is set to be smaller than the volume of the first pressure chamber, so that when the piston is retracted, the hydraulic oil in the first pressure chamber is And is fed into the second pressure chamber through the communication passage. As a result, the hydraulic oil stored in the second pressure chamber is pressed and discharged from the discharge port.

  On the other hand, when the piston advances, the hydraulic oil is filled from the suction port into the first pressure chamber, which is at a low pressure, and the hydraulic oil filled into the second pressure chamber when the piston is retracted is , The second pressure chamber is reduced, and the amount of hydraulic oil excluding the minimum volume is discharged to the discharge port.

  Thereby, since the discharge is performed twice in one reciprocation process of the piston, the discharge can be continuously performed, so that the pulse pressure of the discharge pressure is reduced and a stable pumping action can be performed. It has become.

  According to a second aspect of the present invention, the discharge amount of the second pressure chamber is configured to be approximately ½ of the discharge amount of the first pressure chamber.

  According to the present invention, when the piston is retracted and advanced, ½ of the discharge amount of the first pressure chamber is discharged almost evenly, and the first reciprocating step of the piston is performed. The total discharge amount (two discharge amounts) of the two pressure chambers is equal to the discharge amount of the first pressure chamber.

  As a result, it is possible to discharge continuously without reducing the total discharge amount of the piston in one reciprocating process, so that the pulse pressure of the discharge pressure can be halved and a stable pumping action can be performed. It has become.

  The invention described in claim 3 is characterized in that the communication path is provided inside the piston.

  According to the present invention, it is not necessary to separately provide the communication passage inside the pump housing, so that the space in the pump housing can be used effectively and the pump can be downsized.

  Hereinafter, embodiments of a piston pump according to the present invention will be described in detail with reference to the drawings. In the present embodiment, this piston pump is applied to a brake hydraulic pressure control device for a vehicle that controls the hydraulic pressure of an anti-lock brake control device (ABS) or a vehicle behavior stabilization control device (VSC), for example. Is shown.

  As shown in FIG. 1, this piston pump is a radial piston pump disposed in a brake fluid pressure control device, and a pump housing 1 in which an electric motor (not shown) as a drive source is attached to the outer surface; A cam housing chamber 2 provided substantially at the center of the electric motor mounting surface of the pump housing 1 and a cam housing chamber which is attached to the tip end side of a pump shaft (not shown) for transmitting the driving force of the electric motor. 2 and an eccentric cam 3 accommodated together with the pump shaft.

  The pump housing 1 has a pair of cylinder chambers 4, 4 provided symmetrically with respect to the cam housing chamber 2 so as to be orthogonal to the cam housing chamber 2. Hereinafter, for the sake of convenience, only the configuration of one of the cylinder chambers 4 will be described with respect to the configuration of the cylinder chambers 4 and 4.

  The cylinder chamber 4 is formed in a stepped shape so as to pass through substantially the center position of the cam housing chamber 2, and is formed on an opening 4 a that opens on the cam housing chamber 2 side and on the inner end side in the axial direction. An inner recess 4b and an outer recess 4c formed on the axially outer end side are provided.

  In the cylinder chamber 4, a bottomed cylindrical body 5 that closes the axially outer end side of the cylinder chamber 4, and an annular filter member that is fitted and fixed to the opening end of the body 5 14 and a piston 6 whose front end side passes through the filter member 14 in the axial direction and whose rear end side is slidably held in the body 5.

  The body 5 is inserted into the cylinder chamber 4 from the outer surface side of the pump housing 1, and is fixed to the outer recessed portion 4 c by caulking the bottom portion, and the cylinder chamber 4 is fixed to the pump housing 1. It is designed to close from the outer surface side.

  The filter member 14 is formed in a substantially cylindrical shape made of synthetic resin, and a plurality of discharge holes 14a are formed through the radial direction at predetermined positions. A hydraulic oil in a second pressure chamber 12 to be described later is discharged through the discharge hole 14a, and the discharge hole 14a has a mesh shape for filtering the hydraulic oil discharged from the second pressure chamber 12. The filter is applied.

  The filter member 14 has a piston insertion hole 14b through which a distal end portion 6b of a piston 6 described later is inserted at one end side, and an opening end portion at the other end side is fitted to the opening end portion of the body 5. Yes.

  An annular passage 24, which is a slight gap, is provided between the filter member 14 and the cylinder chamber 4, and hydraulic fluid that has flowed out to the outer peripheral side of the filter member 14 through the discharge holes 14a. Are joined and discharged through the annular passage 24.

  The piston 6 includes a diameter-expanded portion 6a having a stepped diameter increase on the rear end side, and a tip portion 6b provided integrally with an end surface of the diameter-expanded portion 6a and having a diameter smaller than the diameter-expanded portion 6a. The enlarged diameter portion 6a is slidably held on the inner peripheral surface of the body 5, and the distal end portion 6b faces the cam housing chamber 2 from the opening 4a.

  The piston 6 is urged toward the cam housing chamber 2 by a return spring 13 disposed on the inner bottom surface of the body 5, and the distal end portion 6 b is in pressure contact with the outer peripheral surface of the eccentric cam 3. The shaft is slid in the axial direction following the rotation of the eccentric cam 3.

  On the other hand, the eccentric cam 3 is provided on the distal end side of the pump shaft, and is attached to an eccentric pin 20 that is eccentric with respect to the shaft center of the pump shaft. It is accommodated and arranged so as to be orthogonal to the axis 6.

  As a result, the eccentric cam 3 is driven to rotate eccentrically by the motor, whereby the outer peripheral surface comes into contact with the tip portions 6b and 6b of the pistons 6 and 6, and the pistons 6 and 6 are alternately arranged. To drive.

  The first pressure chamber 11 and the second pressure chamber 12 are separated from each other by the enlarged diameter portion 6 a of the piston 6 inside the body 5 and the filter 14.

  The first pressure chamber 11 is defined by a space defined between the body 5 and the enlarged diameter portion 6a of the piston 6 and surrounded by the inner surface of the body 5 and the rear end surface of the enlarged diameter portion 6a. Has been.

  In addition, a plurality of suction holes 5a for sucking hydraulic oil into the first pressure chamber 11 are formed in the peripheral wall of the body 5 along the radial direction, and an annular shape orthogonal to the suction holes 5a. The communication groove 5b is notched. As a result, the hydraulic oil flows on the outer periphery of the body 5 through the communication groove 5b and flows into the first pressure chamber 11 through the suction hole 5a.

  On the other hand, the second pressure chamber 12 has the tip 6b of the piston 6 extending from the vicinity of the opening end of the body 5 to the inside of the cam housing chamber 2, so that the filter member 14 and the piston 6 The space is defined between the enlarged diameter portion 6 a and the distal end portion 6 b, and is defined by a space surrounded by the outer peripheral surface of the piston 6 and the inner peripheral surface of the filter member 14.

  And as for the said piston 6, the outer diameter D2 of the front-end | tip part 6b is set to about 1/2 of the outer diameter D1 of the enlarged diameter part 6a.

  As a result, the volume of the second pressure chamber 12 is approximately ¼ of the volume of the first pressure chamber 11 when the piston 6 is fully advanced, while the first pressure chamber 11 is when the piston 6 is fully retracted. It is set to be approximately equal to the volume of.

  That is, the stroke amount of the piston 6 is such that the volume V1 of the first pressure chamber 11 when the piston 6 is fully retracted (the minimum volume of the first pressure chamber) is the volume V3 of the first pressure chamber 11 when the piston 6 is fully advanced. On the other hand, the volume V4 of the second pressure chamber 12 (the minimum volume of the second pressure chamber) when the piston 6 reaches the maximum is the second when the piston 6 is fully retracted. It is set to be 1/2 of the volume V2 of the two pressure chambers 12 (the maximum volume of the second pressure chamber).

  In addition, a communication passage 15 that connects the first pressure chamber 11 and the second pressure chamber 12 is formed in the piston 6. The communication passage 15 includes a passage hole 15a provided in the axial direction from the rear end surface of the enlarged diameter portion 6a to the vicinity of the substantially intermediate position in the axial direction of the piston 6, and an axis perpendicular to the inner end portion of the passage hole 15a. Hydraulic oil pressurized in the first pressure chamber 11 is pumped to the second pressure chamber 12 through the communication path 15. It has become so.

  A third check valve 23 that allows only hydraulic fluid to flow from the first pressure chamber 11 side to the second pressure chamber 12 is disposed at the outer end of the passage hole 15a. The hydraulic oil pressurized in the second pressure chamber 12 is prevented from flowing back into the first pressure chamber 11 through the communication passage 15.

  The third check valve 23 is a normal check valve, and is fixed to the opening edge of the passage hole 15a, and has a seat member 23a having an oil hole at a substantially central position, and opens and closes the oil hole of the seat member 23a. A check ball 23b, a retainer 23c fixed to the seat member 23a so as to surround the check ball 23b, and formed in a bowl shape having an oil hole at a substantially central position, and held inside the retainer 23c, And a spring 23d for urging the check ball 23b in the closing direction.

  Further, in the inner recess 4 b of the cylinder chamber 4, an annular guide ring 16 that guides the axial sliding of the piston 6, and between the second pressure chamber 12 and the cam housing chamber 2. An annular seal member 17 that holds the gap is press-fitted in order from the outside.

  In the seal member 17, since the piston 6 is slidably held by the guide ring 16, the hydraulic oil in the second pressure chamber 12 moves between the outer peripheral surface of the piston 6 and the inner peripheral surface of the guide ring 16. Leaking into the cam housing chamber 2 through the gap.

  An annular groove is provided on the outer peripheral surface of the enlarged diameter portion 6 a of the piston 6, and an O-ring 18 is fitted into this groove so that the inner peripheral surface of the body 5 and the piston 6 The space between the outer diameter surface of the enlarged diameter portion 6a is sealed. Similarly, an annular groove is provided on the outer peripheral surface of the body 5, and an O-ring 19 is fitted in the same manner as the piston 6, so that the inner peripheral surface of the cylinder chamber 4 and the outer periphery of the body 5 are fitted. Seals between the surfaces.

  As shown in FIGS. 1 to 3, the hydraulic pressure circuit connected to the master cylinder 9 and the communication groove 5 b of the body 5 are communicated with the pump housing 1 to supply hydraulic oil to the first pressure chamber 11. A suction port 7 for sucking in is provided. A first check valve 21 that allows only hydraulic fluid to flow from the master cylinder 9 side to the first pressure chamber 11 side is disposed at the opening end of the suction port 7 on the cylinder chamber 4 side. It is installed.

  On the other hand, a discharge port for discharging the hydraulic oil in the second pressure chamber 12 through communication between the discharge hole 14a of the filter member 14 and a hydraulic circuit connected to the wheel cylinders 10 and 10 of the brakes provided in each wheel. 8 is provided. In addition, a second check valve 22 that allows only hydraulic fluid to flow from the second pressure chamber 12 side to the wheel cylinder 10 side is arranged at the opening end of the discharge port 8 on the cylinder chamber 4 side. It is installed.

  The first check valve 21 and the second check valve 22 are check valves similar to the third check valve 23.

  Next, the operation of this piston pump will be described with reference to FIGS. It is assumed that the hydraulic oil is filled in the first pressure chamber 11 and the second pressure chamber 12 with the maximum retreat of the piston 6 as a base point.

  As shown in FIGS. 1 and 2, the piston pump first moves into the second pressure chamber 12 when the piston 6 pushed into the cylinder chamber 4 is pushed back by the urging force of the return spring 13 and advances. The hydraulic oil having a volume V2 filled in is pressurized by the diameter-enlarged portion 6a of the piston 6 until it reaches a volume V4 that is ½ of the volume V2.

  Then, after being filtered by the filter through each discharge hole 14a of the filter member 14, it is discharged to the discharge port 8 side through the annular passage 24, pushes the second check valve 22 open, and the discharge port 8 is sent to the wheel cylinder 10 by pressure.

  As described above, when the piston 6 is advanced to the maximum, the hydraulic oil having a volume that is a difference between the maximum volume V2 and the minimum volume V4 of the second pressure chamber 12, that is, 1/2 of the maximum volume V2 (equivalent to the minimum volume V4). Is discharged from the second pressure chamber 12 through the discharge port 8. The remaining half volume of the hydraulic fluid having the minimum volume V4 remains in the second pressure chamber 12 and is stored.

  On the other hand, hydraulic oil pumped from the master cylinder 9 enters the first check valve 21 through the suction port 7 into the first pressure chamber 11 which has been expanded to a low pressure as the piston 6 advances. Is opened and flows into the communication groove 5b of the body 5, so that the first pressure chamber 11 is filled through the suction hole 5a.

  As a result, when the piston 6 is advanced to the maximum, the volume in the first pressure chamber 11 is the maximum, and the volume in the second pressure chamber 12 is the minimum. The volume V4 of the hydraulic oil in the second pressure chamber 12 at this time Is ¼ of the volume V3 of the hydraulic oil in the first pressure chamber 11.

  Subsequently, when the piston 6 is pressed and retracted with the rotation of the eccentric cam 3, as shown in FIGS. 1 and 3, the hydraulic oil of the volume V3 filled in the first pressure chamber 11 is The piston 6 is pressurized by the rear end surface of the enlarged diameter portion 6a until the volume V1 is ½ of the volume V3.

  As a result, the volume that is the difference between the maximum volume V3 and the minimum volume V1 of the first pressure chamber 11, that is, the hydraulic oil that is ½ of the maximum volume V3 (corresponding to the minimum volume V1) is the third check valve 23. Is opened and filled into the second pressure chamber 12 through the communication passage 15.

  However, the second pressure chamber 12 has a stored volume V4 of hydraulic oil, and the maximum volume V2 of the second pressure chamber 12 when the piston 6 is fully retracted is the minimum volume of the first pressure chamber 11. Since it is equal to V1, the stored hydraulic fluid of the volume V4 is displaced by the hydraulic oil of the volume V1 pumped from the first pressure chamber 11 and discharged through the discharge port 8. .

  In this way, when the pistons 6 and 6 reciprocate as the eccentric cam 3 rotates, the piston 6 performs two discharges for each reciprocating process, and the discharge capacity of the piston pump is reduced. Since the hydraulic oil is discharged in two equal parts, as shown in FIG. 4, the pulse pressure P of the discharge pressure of the piston pump is ½ of the pulse pressure P0 of the conventional piston pump. .

  Therefore, according to this embodiment, at the time of the maximum advancement of the piston 6, a space having a volume that is approximately 1/4 of the volume of the first pressure chamber 11 is provided in the second pressure chamber 12. By storing approximately ½ of the hydraulic oil pumped from the first pressure chamber 11, two discharges are performed per one reciprocation process of the piston 6, and in the second pressure chamber 12, the first pressure It is possible to discharge almost half of the discharge amount of the chamber 11 almost uniformly.

  Further, the volume of the first pressure chamber 11 when the piston 6 is fully advanced and the volume of the second pressure chamber 12 when the piston 6 is fully retracted are set to be approximately equal, so that in one reciprocation process of the piston 6. The total discharge amount of the second pressure chamber 12 is substantially equal to the discharge amount of the first pressure chamber 11.

  As a result, the piston pump can continuously discharge without reducing the total discharge amount of one reciprocating process of the piston 6, and thus the pulse pressure of the discharge pressure can be halved, and a stable pump action can be achieved. It can be carried out.

  Further, since the communication passage 15 is formed inside the piston 6, it is not necessary to provide the communication passage 15 separately inside the pump housing 1, so that the space in the pump housing 1 can be used effectively. The overall pump can be downsized.

  The present invention is not limited to the configuration of the above-described embodiment. For example, the shape and size of the cylinder chamber 4, the body 5, and the piston 6, and the stroke amount of the piston 6 It can be freely changed according to the specifications and size of each.

  Further, the communication passage 15 can be provided not outside the piston 6 but outside the cylinder chamber 4, that is, inside the pump housing 1.

  Further, the cylinder chamber 4, the body 5 and the piston 6 may be arranged in any of the vertical arrangement and the horizontal arrangement with respect to the pump housing 1 as long as the cylinder chamber 4, the body 5 and the piston 6 are arranged opposite to each other with the eccentric cam 3 as a center. The same operational effects as those of the above-described embodiment are achieved.

  In the above embodiment, an example of two cylinders has been described. However, the present invention is not limited to a two-cylinder reciprocating piston pump, and can be implemented as a single cylinder. By arranging the cylinder chamber 4, the body 5 and the piston 6 radially in the circumferential direction around the eccentric cam 3, it can be implemented as a radial reciprocating piston pump.

It is a partial expanded sectional view of the piston pump which shows embodiment of the piston pump which concerns on this invention, and demonstrates the principal part of this invention. FIG. 3 is a hydraulic circuit schematic diagram illustrating an embodiment of the piston pump and explaining an operation in a first pressure chamber suction process (at the time of piston advancement). FIG. 3 is a hydraulic circuit schematic diagram illustrating an embodiment of the piston pump and explaining an operation in a discharge process (when the piston is retracted) of a first pressure chamber. It is a hydraulic pressure waveform chart which shows the waveform of the discharge pressure of the piston pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pump housing 4 ... Cylinder chamber 6 ... Piston 7 ... Intake port 8 ... Discharge port 11 ... 1st pressure chamber 12 ... 2nd pressure chamber 15 ... Communication path 21 ... 1st check valve 22 ... 2nd check valve 23 ... Third check valve

Claims (3)

A pump housing having a suction port and a discharge port; and a cylinder chamber communicated with the suction port and the discharge port;
A piston that is slidably accommodated in the cylinder chamber, is driven by a drive source, and performs a pump action by reciprocating in the axial direction;
A first check valve that allows only flow from the suction port to the cylinder chamber;
A second check valve that allows only flow from the cylinder chamber to the discharge port;
A first pressure chamber in communication with the suction port and separated by the piston;
A second pressure chamber communicated with the discharge port and having a volume that changes relative to the first pressure chamber by reciprocating movement of the piston;
A communication path for communicating the first pressure chamber and the second pressure chamber;
A third check valve disposed in the communication path and allowing only flow from the first pressure chamber side to the second pressure chamber side;
With
The first pressure chamber is formed on the bottom side of the piston, while the second pressure chamber is formed on the outer periphery on the front end side of the piston that penetrates the cylinder chamber in the axial direction. Also set the volume small,
A piston pump configured to reduce the second pressure chamber while leaving a predetermined volume space when the piston is advanced to the maximum. 2. The piston pump according to claim 1, wherein a discharge amount of the second pressure chamber is configured to be approximately ½ of a discharge amount of the first pressure chamber. The piston pump according to claim 1, wherein the communication path is provided inside the piston.

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