JP4255075B2 - Piston pump - Google Patents

Description

  The present invention is used in various hydraulic systems including a brake control system such as an anti-skid brake control (hereinafter also referred to as ABS control) device of an automobile, and a piston that sucks and discharges hydraulic fluid by reciprocating movement of the piston. It relates to the technical field of pumps.

  Conventionally, ABS control is known as one type of brake control for automobiles. In this ABS control, when it is detected that a wheel tends to be locked during braking, the braking force of the wheel is weakened to cancel the locking tendency, and then the braking force is increased again to stabilize the vehicle operation. At the same time, brake control is performed so as to shorten the braking distance.

FIG. 5 is a diagram schematically illustrating an example of a two-system brake control system that performs conventional general ABS control. In the figure, 1 is a brake control system, 2 is a brake pedal, 3 is a brake booster, 4 is a tandem master cylinder, 5 is a brake fluid passage of the first system, 5a is a branch passage, 5a ₁ is a branch passage 5a. branch passage, 5b branch passages, 5b ₁ branch passage branch passage 5b, 5c are discharge passages, 5d the ring passage, the brake fluid passage of the second system is 6, 6d ring passage, 7 the branch passage 5a The first wheel cylinder connected, 8 is a first wheel cylinder connected to the branch passage 5b, 9 is a pressure increasing valve comprising a normally open electromagnetic on-off valve provided in the branch passage 5a, and 10 is a branch passage. 5b is a pressure-increasing valve comprising a normally-open electromagnetic on-off valve, 11 is a check valve that bypasses the pressure-increasing valve 9 and allows only the flow of brake fluid from the wheel cylinder 7 to the master cylinder 4, and 12 is a pressure-increasing valve 1 A check valve 13 that bypasses 0 and allows only the flow of brake fluid from the wheel cylinder 8 toward the master cylinder 4, and is a normal valve 13 provided in the branch passage 5 a on the wheel cylinder 7 side from the pressure increasing valve 9 and the check valve 11. A pressure reducing valve 14 comprising a closed electromagnetic on-off valve, 14 a pressure reducing valve comprising a normally closed electromagnetic on-off valve provided in the branch passage 5b on the wheel cylinder 8 side from the pressure increasing valve 10 and the check valve 12, and 15 a first system Low pressure accumulator connected to the discharge passage 5c and the circulation passage 5d, 16 is a pump provided in the circulation passage 5d of the first system, 17 is a suction port of the pump 16, 18 is a discharge port of the pump 16, and 19 is a discharge port of the pump 16. Piston, 20 is a pump chamber of the pump 16, 21 is a suction valve made up of a check valve of the pump 16, 22 is a discharge valve made up of a check valve of the pump 16, and 23 is a ring of the second system A pump provided in the passage 6d, 24 is a suction port of the pump 23, 25 is a discharge port of the pump 23, 26 is a piston of the pump 23, 27 is a pump chamber of the pump 23, 28 is a suction valve consisting of a check valve of the pump 23 Reference numeral 29 denotes a discharge valve composed of a check valve of the pump 23, 30 denotes a piston drive member that rotates eccentrically and drives both pistons 19, 27, and 31 denotes a motor (M) that rotates the piston drive member 30.
As for the second system, only a part of the brake fluid passage 6 of the second system, a part of the circulation passage 6d, and the pump 23 are shown, but the configuration of the second system is the first system. The configuration is exactly the same.

  In the brake control system configured as described above, the pressure-increasing valves 9 and 10 and the pressure-reducing valves 13 and 14 are normally in the illustrated state, and the first hydraulic pressure chamber (not illustrated) and the first system of the master cylinder 4 are not illustrated. The wheel cylinders 7 and 8 communicate with each other, and a second hydraulic chamber (not shown) of the master cylinder 4 and two wheel cylinders (not shown) of the second system communicate with each other. Accordingly, when the brake pedal 2 is depressed, the brake booster 3 is operated, and the master cylinder 4 is operated by the output of the brake booster 3. The brake fluid pressure corresponding to the pedal depression force is generated in the first and second hydraulic pressure chambers, respectively. The brake fluid pressure in the first fluid pressure chamber is supplied to the wheel cylinders 7 and 8 through the brake fluid passage 5 of the first system, the branch passages 5a and 5b, and the pressure increasing valves 9 and 10, respectively. Operate. Similarly, the brake fluid pressure in the second fluid pressure chamber is supplied to the second system wheel cylinder, and the second system brake operates.

  During this braking, for example, if a tendency to lock the wheel 32 braked by the wheel cylinder 7 of the first system is detected, the pressure increasing valve 9 is closed and the pressure reducing valve 13 is opened. Then, the brake fluid in the wheel cylinder 7 is discharged to the low-pressure accumulator 15 through the discharge passage 5c, so that the brake fluid pressure in the wheel cylinder 7 is reduced. Thereby, the braking force generated by the wheel cylinder 7 is reduced.

  When the tendency of the wheel 32 to lock is eliminated due to a decrease in the braking force of the wheel cylinder 7, the motor 31 is driven to drive the pump 16, the pressure increasing valve 9 is opened, and the pressure reducing valve 13 is closed. Then, the pump 16 sucks the brake fluid of the low pressure accumulator 15 through the circulation passage 5d and discharges it to the brake fluid passage 5. The brake fluid discharged from the pump 16 is fed again to the wheel cylinder 7 through the branch passage 5a and the pressure increasing valve 9. As a result, the brake pressure of the wheel cylinder 7 is increased, and the brake force of the wheel 32 is increased. In this way, ABS control is performed so as to eliminate the tendency of the wheels 32 to lock.

Conventionally, piston pumps are often used for the first and second pumps 16, 23 used in such a brake control system. As this piston pump, the piston is guided by a cylindrical guide member and a housing holding the guide member, and the working fluid sucked from the suction port is sealed from the guide member to the inside of the housing. A piston pump provided with a member has been proposed (see, for example, Patent Document 1).
Special table 2003-529018 gazette.

  However, since the seal member of the piston pump used in such a brake control system is provided inside the guide member, when the piston pump is completed, when the finished product inspection by pneumatic pressure or hydraulic pressure is performed, the guide member is The air or oil does not flow out. For this reason, it is impossible to reliably detect a shortage of the seal member and a seal failure of the seal member. In addition, since the seal member cannot be visually recognized, similarly, a missing part of the seal member and a seal failure of the seal member cannot be easily detected.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a piston pump that can easily and reliably detect a missing seal member and a seal failure of the seal member after completion. That is.

In order to solve the above-described problems, the invention of claim 1 includes a suction valve that sucks in the working fluid, a discharge valve that discharges the working fluid, a piston that is housed in a housing and reciprocates in the axial direction, and the piston A piston driving member that drives the piston, a cylindrical guide member that is supported by the housing and slidably guides the piston driving member side end portion of the piston, and at least one of the inner and outer circumferences of the guide member And at least a seal member that prevents leakage to the piston drive member side, and the suction valve and the discharge valve are selectively opened and closed by the reciprocating movement of the piston, thereby sucking and discharging the hydraulic fluid. In the piston pump, the guide member protrudes in a radial direction from an axial guide portion and an end portion of the guide portion opposite to the piston drive member side. It is formed in an L-shaped cross section from the formed annular flange portion, and the guide member is provided with a groove for detecting occurrence of a missing part of the seal member or occurrence of a seal failure of the seal member when a fluid flows. The groove is a radial groove provided on the seal member side end surface of the guide member .

The invention according to claim 2 is characterized in that the groove is also an axial groove provided on at least one of the inner peripheral surface and the outer peripheral surface of the guide member.
Further, the invention of claim 3 is characterized in that at least a part of the axial groove is inclined with respect to the axial direction of the piston.
Furthermore, the invention of claim 4 is characterized in that the groove is a radial groove provided on a seal member side end surface of the guide member.

  According to the piston pump according to the first to fourth aspects of the present invention constructed as above, even when the seal member is missing from the completed piston pump, or even if the seal member is mounted, this seal member If the seal is defective, when air of a predetermined pressure, which is fluid, is introduced from the suction port, the air flows through the groove of the guide member and flows out to the side opposite to the seal member. It is possible to reliably and easily detect a sealing failure of a product or a seal member.

Further, since the groove is formed as a radial groove provided on the end surface of the guide member on the seal member side, when a seal failure occurs on the outer periphery side of the seal member, the air that has passed through the outer periphery side of the seal member It flows through this engagement direction groove and passes through a minute gap between the outer peripheral surface of the piston and the inner peripheral surface of the guide member, or when an axial groove is formed in the guide portion, the effect is passed through this axial groove. Can be spilled. Therefore, it is possible to reliably detect a seal failure on the outer peripheral side of the seal member.

In particular, according to the inventions of claims 2 and 3, since the groove is formed as an axial groove provided on at least one of the inner peripheral surface and the outer peripheral surface of the guide member, air flows through the axial groove. It is possible to effectively flow out, and it is possible to more reliably detect a missing part of the seal member or a seal failure of the seal member.
In that case, according to the invention of claim 3, since the axial groove is provided so that at least a part thereof is inclined with respect to the axial direction of the piston, the piston tilts in the axial direction. However, it is possible to prevent the piston from fitting in the axial groove. As a result, the guide function of the guide member that supports the sliding and falling of the piston can be reliably exhibited.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of an embodiment of a piston pump according to the present invention. Note that each of the pumps 16 and 23 used in the brake control system 1 shown in FIG. 5 is composed of the same piston pump. Therefore, in this example, the piston pump of the present invention is described as being used in the brake control system 1 shown in FIG. 5 described above, and the same components as in the brake control system 1 are denoted by the same reference numerals, Detailed description is omitted. Moreover, in the following description, the piston pump of the present invention corresponding to the pump 23 of the second system will be described, and for convenience of description, this piston pump is denoted by reference numeral 23. Further, in the following description, “right” and “left” are “right” and “left” in the drawings, respectively.

  As shown in FIG. 1, the piston pump 23 of this example has a pump housing 33, and the pump housing 33 has a pump hole 34 formed of a stepped hole penetrating in the axial direction. The pump hole 34 is fitted with a pump cylinder 35 and a cover 36 fixed to the pump cylinder 35 by press fitting. The annular radial projecting portion 35a of the pump cylinder 35 is brought into contact with the stepped portion 33a of the pump housing 33, and the pump housing 33 is caulked and the cover 36 is fixed, whereby the pump cylinder 35 and the cover 36 are fixed. Are fixed to the pump housing 33 in the axial direction.

  The pump cylinder 35 is formed in a bottomed cylindrical shape having a cylinder bottom portion 35b, and the piston 26 is accommodated in the pump cylinder 35 over a substantially half length on the left side in FIG. In that case, a part of the piston 26 is fitted and supported by the pump cylinder 35 so as to be slidable. A ring-shaped seal member 37 is fitted to the left side portion of the piston 26. The seal member 37 prevents brake fluid from leaking between the outer peripheral surface of the piston 26 and the inner peripheral surface of the pump cylinder 35.

  A bottomed cylindrical retainer 38 is fixed to the left end portion of the piston 26 by press fitting. The inner peripheral side and the outer peripheral side of the retainer 38 are always in communication with a communication hole or a communication groove (not shown). The brake fluid can flow. A seal member 37 is sandwiched in the axial direction between the right end of the retainer 38 and the step portion 26 a of the piston 26. The retainer 38 is always urged rightward by a return spring 39 that is contracted between the retainer 38 and the cylinder bottom 35b. As a result, the return spring 39 constantly urges the piston 26 in the direction of exiting from the right pump cylinder 35.

  The right end of the piston 26 protruding rightward from the pump cylinder 35 is slidably guided by a guide member 40 formed in a cylindrical shape from resin. As shown in FIG. 2, the guide member 40 is formed integrally with a piston guide portion 40a that extends in the axial direction and slidably guides the piston 26, and protrudes in the radial direction at the left end portion of the piston guide portion 40a. The annular flange portion 40b is formed in an L-shaped cross section. Therefore, the radial thickness of the guide member 40 is such that the portion where the flange portion 40b is formed is thick, and the portion where the flange portion 40b is not formed is thin. The piston drive member side end portion 26b of the piston 26 is slidably guided only by the piston guide portion 40a. The guide member 40 is not limited to resin and can be formed of other materials such as metal.

  Three axial grooves 40d are provided on the inner peripheral surface of the piston guide portion 40a so as to penetrate the piston guide portion 40a in the axial direction and at equal intervals in the circumferential direction. Further, three radial grooves 40e communicating with the respective axial grooves 40d are provided on the end surface of the guide member 40 on the flange portion 40b side at equal intervals in the circumferential direction.

  As shown in FIG. 1, the guide member 40 is positioned in the axial direction by the flange portion 40b coming into contact with the stopper 33b, which is a step portion of the pump housing 33, from the left side. It is supported. The length L in the axial direction of the guide member 40 is such that the piston drive member side end 40c on the right side of the guide member 40 is the piston contact portion of the piston drive member 30 in a state where the guide member 40 is supported by the pump housing 33. It is preferable to set it as long as possible at a position where it does not interfere with the piston drive member 30 when it is eccentric to the left piston 26 side at the maximum. As an example, as shown by a two-dotted line in FIG. 1, the position P of the piston drive member side end 26d of the piston 26 when the piston 26 moves to the left in the discharge direction at the maximum, It can be set to be the same position as the position P in contact with the piston contact portion of the eccentric piston drive member 30 or a position near the position P. Of course, it is not limited to this. Thus, by setting the axial length of the piston guide portion 40 a of the guide member 40, the axial length of the piston guide portion 40 a can be effectively increased, and the piston 26 is stabilized by the guide member 40. Be guided.

  Further, a seal ring 41 which is a seal member of the present invention is disposed in the pump hole 34 adjacent to the left side of the guide member 40. In that case, the radial thickness of the seal ring 41 is the same as or substantially the same as the radial thickness of the annular flange portion 40b of the guide member 40, and the annular flange portion 40b is formed. A seal ring 41 is backed up over the entire left end of the guide member 40. As shown in FIG. 3, the seal ring 41 is composed of an X seal ring having a cross section formed in an X shape. Of course, the seal ring 41 is not limited to the X seal ring, and may be formed of other seal members such as a cup seal. The piston 26 slidably penetrates the seal ring 41, and the seal ring 41 provides a liquid-tight seal between the outer peripheral surface of the piston 26 and the inner peripheral surface of the pump hole 34.

The piston 26 is formed with a radial flow hole 42 that opens to the outer peripheral surface thereof and an axial flow hole 43 that communicates with the radial flow hole 42 and opens at the left end of the piston 26. In this case, the center of the axial flow hole 43 coincides with the central axis α of the piston 26. The radial flow hole 42 is always in communication with the suction port 24 regardless of the sliding of the piston 26. A suction valve 28 is provided at the left end opening of the axial flow hole 43. The suction valve 28 includes a ball valve 28a, a valve seat 28b that is provided at the left end of the piston 26 at the periphery of the opening end of the axial flow hole 43, and on which the ball valve 28a can be seated and separated, and the ball valve 28a is a valve seat 28b. And a valve spring 28c that is constantly urged in the direction of being seated.
A cylindrical filter 44 is attached to the right end portion of the pump cylinder 35 by snap coupling.

  A through hole 46 that penetrates in the axial direction is formed in the cylinder bottom 35 b of the pump cylinder 35 at the position of the central axis α of the piston 26. A discharge valve 29 is provided at the left end opening of the through hole 46. The discharge valve 29 includes a ball valve 29a, a valve seat 29b that is provided at the left end of the cylinder bottom 35b at the opening end periphery of the through hole 46, and the ball valve 29a can be seated on and off, and the ball valve 29a as a valve seat 29b. The valve spring 29c is always urged in the seating direction. The ball valve 29 a is accommodated in the axial hole 47 of the cover 36 so as to be movable in the axial direction, and the valve spring 29 c is also accommodated in the axial hole 47. The axial hole 47 communicates with the discharge port 25 through a passage groove 48 formed in the cover.

  The piston 26 is urged to the right by the return spring 39 as described above, and the right end thereof is in contact with the disk-like piston drive member 30. In that case, the contact point Q between the piston 26 and the piston driving member 30 is set at a position shifted from the central axis α of the piston 26. That is, the straight line β connecting the contact point Q and the rotation axis of the piston driving member 30 is offset from the central axis of the piston 26.

  In the piston pump 23 configured as described above, it is not possible to inspect whether or not the seal ring 41 is properly attached to the finished piston pump 23, that is, a missing part of the seal ring 41 by direct observation. Even if the seal ring 41 is attached, it cannot be inspected by direct view whether or not the seal ring 41 has a sealing failure.

  Therefore, it is necessary to inspect the seal ring 41 for missing parts and defective seals. When inspecting a missing part of the seal ring 41 and a defective seal, air of a predetermined pressure as a fluid is introduced into the pump hole 34 from the suction port 24 of the completed piston pump 23. When the seal ring 41 is properly attached, the air introduced from the suction port 24 is prevented from leaking out by the seal ring 41 and therefore does not flow out from the pump hole 34 to the piston drive member 30 side. By recognizing manually that the air does not flow out, the proper attachment of the seal ring 41 is detected. In addition, when the seal ring 41 is missing or when a seal failure occurs even when the seal ring 41 is mounted, the air introduced from the suction port 24 flows into the radial groove 40e and the shaft of the guide member 40. It flows in the direction groove 40d and flows out from the pump hole 34 to the piston drive member 30 side opposite to the seal ring 41 side. By recognizing the outflow of air manually or the like, occurrence of a missing part of the seal ring 41 or a seal failure of the seal ring 41 is detected.

Next, the suction and discharge operations of the piston pump 23 of this example will be described.
In the state shown in FIG. 1, the piston 26 is in the right limit position. When the piston drive member 30 is eccentrically rotated clockwise as indicated by the arrow by the motor 31 from this state, the pressing force to the left of the piston 26 increases. The piston 26 moves to the left against the spring force of the return spring 39. For this reason, the pressure in the pump chamber 27 is increased, the ball valve 29a is separated from the valve seat 29b, and the discharge valve 29 is opened. As a result, the brake fluid in the pump chamber 27 is discharged from the discharge port 25 through the through hole 46, the opened discharge valve 29 and the passage groove 48.

  Next, when the pushing force to the left of the piston 26 decreases due to the eccentric rotation of the piston driving member 30, the piston 26 moves to the right by the spring force of the return spring 39. For this reason, the pressure in the pump chamber 27 is lowered, the ball valve 29a is seated on the valve seat 29b and the discharge valve 29 is closed, and the ball valve 28a is separated from the valve seat 28b and the suction valve 28 is opened. As a result, the brake fluid of the low-pressure accumulator 15 is sucked from the suction port 24 and flows into the pump chamber 27 via the filter 44, the radial flow hole 42, the axial flow hole 43, and the opened suction valve 28. At this time, the brake fluid sucked into the pump hole 34 from the suction port 24 by the seal ring 41 passes through at least one of the inner and outer circumferences of the guide member 40 and leaks to the piston drive member 30 side to the right of the pump hole 34. Is prevented.

  When the pushing force to the left of the piston 26 increases again due to further eccentric rotation of the piston driving member 30, the piston 26 moves to the left as described above, and the brake fluid is discharged from the discharge port 25. Thus, the piston 26 is repeatedly reciprocated in the left-right direction, and the suction valve 28 and the discharge valve 29 are selectively opened and closed, whereby the brake fluid of the low-pressure accumulator 15 is sucked from the suction port 24 and discharged from the discharge port 25. The

  Thus, according to the piston pump 1 of this example, when the seal ring 41 is missing from the completed piston pump 1 or even if the seal ring 41 is attached, the seal ring 41 has a poor seal. In this case, when air of a predetermined pressure is introduced from the suction port 24, the air flows out through the radial groove 40e and the axial groove 40d of the guide member 40. Therefore, the missing part of the seal ring 41 or the seal ring 41 It is possible to reliably and easily detect a sealing failure. In particular, since the radial groove 40e is provided in communication with the axial groove 40d on the end face of the guide member 40 on the side where the seal ring 41 is provided, either the inner peripheral side or the outer peripheral side of the seal ring 41 is provided. It is possible to reliably detect a sealing failure.

In addition, a cylindrical guide member 40 that slidably guides the piston drive member side end portion 26b of the piston 26 is provided with an axial piston guide portion 40a and a radial direction formed at one end portion of the piston guide portion 40a. Since the piston portion 40 is slidably guided by the piston guide portion 40a and the entire end surface of the flange portion 40 forming portion of the guide member 40 is sealed with the flange portion 40. 41 can be backed up. Thereby, since the thickness of the piston guide part 40a can be made thin, the tilting of the piston 26 with respect to the central axis α can be effectively suppressed even when an uneven load is applied to the piston 26, and the guide member 40 The durability of can be improved.
Even if the thickness of the piston guide portion 40a is reduced, the entire seal ring 41 can be backed up by the guide member 40, and a reduction in the backup function of the guide member 40 can be prevented.

  In the above example, three axial grooves 40d and three radial grooves 40e provided in the seal member 40 are provided, but the number of these grooves 40d and 40e is not necessarily limited to three. One or more arbitrary numbers can be provided. Further, when a plurality of these grooves 40d and 40e are provided, they may be provided at unequal intervals in the circumferential direction, but these grooves 40d and 40e are preferably provided at equal intervals in the circumferential direction.

  Further, in the above-described example, each axial groove 40d is provided in the axial direction of the guide member 40. However, as shown in FIGS. 4A and 4B, each axial groove 40d is formed in the axis of the guide member 40. It can also be provided in a straight line inclined obliquely with respect to the direction. By inclining the axial groove 40d in this manner, the force acting on the guide member 40 by air can be dispersed and the guide member 40 can be prevented from opening.

  The guide member 40 supports the sliding and falling of the piston 26. However, when the axial groove 40d is provided linearly in the axial direction of the guide member 40, as shown in FIG. When the collapse occurs, there is a possibility that the whole piston 26 fits in the axial groove 40d. If the entire piston 26 is fitted into the axial groove 40d in this way, the guide function of the guide member 40 that supports the sliding and falling of the piston 26 may be reduced. However, by tilting the axial groove 40d in this way, even if the piston 26 falls down, it is possible to prevent the entire piston 26 from being fitted into the axial groove 40d. Thereby, it is possible to reliably exhibit the guide function of the guide member 40 that supports the sliding and falling of the piston 26.

Furthermore, as a similar modification, as shown in FIG. 4C, each axial groove 40d can be provided so as to be inclined with respect to the axial direction of the guide member 40 and curved in one direction. Furthermore, as shown in FIG. 4D, each axial groove 40d can be curved and the openings 40d ₁ and 40d ₂ of each axial groove 40d can be provided in the axial direction. In this case, the air flowing through each axial groove 40d flows in the axial direction into each axial groove 40d and flows out from each axial groove 40d in the axial direction. This makes it possible to detect the missing part of the seal ring 41 more reliably. In this case, even if the openings 40d ₁ and 40d ₂ of the axial grooves 40d are axial, the other portions of the axial grooves 40d are curved, so that the entire piston 26 is fitted into the axial grooves 40. In the same manner, the guide function of the guide member 40 described above can be surely exhibited. Furthermore, the axial groove 40d can be formed as a screw groove.

Furthermore, radial grooves 40e may be provided alone. Further, the radial groove 40e can be used in combination with a groove through which air flows provided on the outer peripheral surface of the guide member 40, or can be used in combination with the groove on the outer peripheral surface of the guide member 40 and the groove 40d. it can. When the guide member 40 is provided with the radial groove 40e alone, air that has passed through the outer periphery of the seal ring 41 passes through the radial groove 40e due to a seal failure on the outer periphery of the seal ring 41. It flows out to the piston drive member side through a minute gap between the outer peripheral surface and the inner peripheral surface of the guide member 40. Thereby, it is possible to detect a sealing failure on the outer peripheral side of the seal ring 41.

  Further, in the above-described example, the piston pump 1 of the present invention is applied to a brake control system that performs ABS control. However, the present invention is not limited to this, and other ABS control, traction The present invention can be applied to any hydraulic system as long as the hydraulic system includes at least the piston pump 1, such as another brake control system such as control or automatic brake, or a hydraulic control system other than the brake.

  The piston pump according to the present invention is used in a brake control system such as ABS control, traction control or automatic brake in a vehicle such as an automobile, and is used in a hydraulic control system other than the brake, and sucks hydraulic fluid by reciprocating movement of the piston. It can be suitably used for a piston pump for discharging.

It is sectional drawing which shows an example of embodiment of the piston pump which concerns on this invention. The guide member used for the piston pump of the example shown in FIG. 1 is shown, (a) is a front view, (b) is sectional drawing which follows the IIB-IIB line | wire in (a). It is sectional drawing of the seal ring used for the piston pump of the example shown in FIG. The modification of the guide member of the piston of this invention is shown, (a) is a side view of one modification of a guide member, (b) is the figure seen from the IVB direction in (a), (c) is the other of a guide member The same figure as (b) which shows the modification of (b), (d) shows the other modification of a guide member, The figure similar to (b), (e) is fitting in the groove | channel of a guide member. It is a figure explaining. It is a figure which shows typically an example of the 2 systems brake control system which performs the conventional general ABS control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Brake control system, 23 ... Piston pump, 24 ... Suction port, 25 ... Discharge port, 26 ... Piston, 27 ... Pump chamber, 28 ... Suction valve, 29 ... Discharge valve, 30 ... Piston drive member, 31 ... Motor ( M), 33 ... Pump housing, 33b ... Stopper, 34 ... Pump hole, 35 ... Pump cylinder, 36 ... Cover, 40 ... Guide member, 40a ... Piston guide part, 40b ... Flange part, 40d ... Axial groove, 40e ... Radial groove , 41 ... seal ring, 42 ... radial flow hole, 43 ... axial flow hole, 44 ... filter, 46 ... through hole

Claims (3)

A suction valve for sucking hydraulic fluid, a discharge valve for discharging the hydraulic fluid, a piston that is housed in a housing and reciprocates in the axial direction, a piston drive member that drives the piston, and a piston supported by the housing A cylindrical guide member that slidably guides the piston drive member side end, and a seal member that prevents the hydraulic fluid from leaking to the piston drive member side through at least one of the inner and outer circumferences of the guide member; In the piston pump that sucks and discharges the hydraulic fluid by selectively opening and closing the suction valve and the discharge valve by the reciprocating motion of the piston,
The guide member is formed in an L-shaped cross section from an axial guide portion and an annular flange portion formed to project radially from an end portion of the guide portion opposite to the piston drive member side. ,
The guide member is provided with a groove for detecting occurrence of a missing part of the seal member or occurrence of a seal failure of the seal member due to fluid flow ,
The piston pump according to claim 1, wherein the groove is a radial groove provided on an end surface of the guide member on a seal member side . The piston pump according to claim 1, wherein the groove is also an axial groove provided on at least one of an inner peripheral surface and an outer peripheral surface of the guide member. The piston pump according to claim 2, wherein at least a part of the axial groove is inclined with respect to the axial direction of the piston.

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