US20130121861A1 - Piston Pump - Google Patents
Piston Pump Download PDFInfo
- Publication number
- US20130121861A1 US20130121861A1 US13/512,022 US201013512022A US2013121861A1 US 20130121861 A1 US20130121861 A1 US 20130121861A1 US 201013512022 A US201013512022 A US 201013512022A US 2013121861 A1 US2013121861 A1 US 2013121861A1
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- US
- United States
- Prior art keywords
- piston
- pump
- cylinder
- sealing ring
- ring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
- B60T8/40—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
- B60T8/40—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
- B60T8/4031—Pump units characterised by their construction or mounting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
- F04B1/0408—Pistons
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
- F04B1/0439—Supporting or guiding means for the pistons
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
- F04B1/0448—Sealing means, e.g. for shafts or housings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/10—Valves; Arrangement of valves
- F04B53/12—Valves; Arrangement of valves arranged in or on pistons
- F04B53/125—Reciprocating valves
- F04B53/126—Ball valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/10—Valves; Arrangement of valves
- F04B53/12—Valves; Arrangement of valves arranged in or on pistons
- F04B53/125—Reciprocating valves
- F04B53/129—Poppet valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/14—Pistons, piston-rods or piston-rod connections
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/14—Pistons, piston-rods or piston-rod connections
- F04B53/143—Sealing provided on the piston
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/16—Casings; Cylinders; Cylinder liners or heads; Fluid connections
- F04B53/162—Adaptations of cylinders
- F04B53/164—Stoffing boxes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
Definitions
- the invention relates to a piston pump for a hydraulic vehicle brake system having a slip control system, the brake system having the features of the preamble of claim 1 .
- Slip control systems for vehicle brake systems are known and they are generally implemented as antilock (brake), traction control and/or vehicle dynamics or antiskid control systems. Customary abbreviations are ABS, ASR, FDR and ESP.
- the piston pumps are used to build up a hydraulic pressure for slip control and are often referred to as return pumps.
- the piston pump can also be used to build up a hydraulic pressure in a vehicle brake system which employs an independent hydraulic energy source.
- Piston pumps for slip-controlled vehicle brake systems have a cylinder and a piston, which can be moved axially in the cylinder and can be driven so as to perform an axially reciprocating stroke motion in the cylinder.
- the cylinder or cylinders of piston pumps for slip control systems of vehicle brake systems are designed as cylindrical bores in a “hydraulic block”, which, in addition to the piston pump, contains further hydraulic components for slip control, such as solenoid valves, hydraulic accumulators and check valves, and connects them hydraulically.
- the stroke motion is imparted to the piston of such piston pumps by an eccentric, which can be driven in rotation by means of an electric motor and on the circumference of which the piston rests by means of an end face.
- a piston return spring which is arranged at an end of the piston facing away from the eccentric, holds the piston end face that faces the eccentric in contact with a circumference of the eccentric.
- the pistons of known piston pumps are sealed off in the cylinder by means of a sealing ring, which is supported axially on a side facing away from a pump chamber by a support ring.
- the pump chamber is a space in the cylinder, the volume of which is increased and reduced alternately during the reciprocating stroke motion of the piston in order alternately to draw in and displace brake fluid, i.e. to deliver brake fluid.
- the pump chamber is situated at the end of the piston facing away from the eccentric.
- the sealing ring is generally composed of a rubber-elastic material, while the support ring is composed of a rigid plastic, the intention being that it should be deformed only slightly, if at all, when subjected to pressure.
- the function of the support ring is to provide axial support for the sealing ring, preferably over as large an area as possible, in order to avoid extrusion of the sealing ring into a gap when subjected to pressure.
- pressures of up to 280 bar can occur and act on the sealing ring.
- Extrusion into a gap means flowing, i.e. plastic, deformation of the sealing ring into a gap between the piston and the cylinder.
- the sealing ring is subjected to pressure on the side facing the pump chamber, and the sealing ring is supported by the support ring on the opposite side, i.e. the side facing away from the pump chamber.
- the support ring has at least one longitudinal passage for fluid, i.e. for brake fluid.
- fluid i.e. for brake fluid.
- the side of the support ring facing the sealing ring communicates with the side thereof facing away from the sealing ring.
- a pressure between the sealing ring and the support ring can arise as a “drag pressure” when there is drag leakage between the sealing ring and the cylinder during the stroke motion of the piston in the cylinder.
- a pressure buildup between the sealing ring and the support ring would shift the sealing ring away from the support ring and, as already explained, is avoided by means of the at least one longitudinal passage in the support ring.
- the sealing ring and the support ring are usually arranged on the piston, i.e. move with the piston.
- the opposite situation, in which the sealing ring and the support ring are arranged in the cylinder and are stationary with the latter, is also conceivable.
- the advantage of the invention is the possibility of relatively large-area axial support of the sealing ring by the support ring over an annular area with an outside diameter which corresponds to an inside diameter of the cylinder and with an inside diameter which corresponds to an outside diameter of the piston, in each case at the location where the sealing ring and the support ring are situated. Only the cross section of the at least one longitudinal passage, at the mouth thereof facing the sealing ring, does not participate in the supporting cross-sectional area.
- the design of the longitudinal passage as a longitudinal groove on an outer or inner circumference of the support ring as claimed in claim 2 has the advantage that the support ring is simple to produce in comparison, for example, with a through hole through the support ring, which would likewise be possible as a longitudinal passage.
- Claim 3 provides the support ring according to the invention on a “compensating piston”.
- Said piston is driven like a pump piston by means of an eccentric, in particular by means of the same eccentric as the pump piston or pistons, but said compensating piston and the cylinder thereof do not have any fluid control, i.e. in particular, do not have either inlet or outlet valves.
- the compensating piston communicates with the pump piston or pistons of the piston pump and reduces the pressure pulsation thereof.
- With its cylinder it can be understood as a hydraulic accumulator, the volume of which varies in synchronism with the stroke motion of the pump piston or pump pistons.
- the compensating piston and the cylinder thereof do not require a separate inlet and outlet, one connection being sufficient, although separate inlets and outlets are not excluded.
- Claim 4 provides an encircling bead on an outside and/or inside of the sealing ring, the crest of which bead rests in a sealing manner on the cylinder and/or the piston.
- crest refers to the “highest” part of the bead, i.e. the part of the bead which runs around at a point radially furthest toward the outside or furthest toward the inside, and, according to claim 5 , the encircling bead is preferably formed on a sealing ring with an otherwise quadrilateral ring cross section.
- the quadrilateral basic shape of the ring cross section makes it possible to achieve high resistance to pressure by the sealing ring, with the sealing ring being comparatively massive.
- the design of the sealing region of the sealing ring as a bead likewise allows relatively massive design and hence high resistance to pressure.
- the importance of resistance to pressure, especially of the sealing region of the sealing ring, is not exclusively in avoiding destruction of the sealing ring but also in keeping deformation of the sealing region to such a low level, when pressure is imposed from one side, that the sealing effect is as far as possible unimpaired.
- Another advantage of the sealing ring designed in accordance with the invention is the pressure activation thereof: when subjected to pressure, the sealing ring is compressed axially and expands radially outward and/or inward, resulting in an increase in a contact force on the cylinder and/or the piston. A good sealing effect, both at low pressure and high pressure is thus achieved, and it is possible for the contact force at low pressure to be low in order to reduce friction and wear.
- Claim 6 provides a cylinder closed at one end. This has the advantage that the end of the cylinder does not have to be closed by means of a separate component.
- FIG. 1 shows a piston and a cylinder in accordance with the invention in an axially sectioned view
- FIG. 2 shows a support ring according to the invention for the piston in FIG. 1 in a perspective view
- FIG. 3 shows a sealing ring according to the invention for the piston from FIG. 1 in a perspective half section
- FIG. 4 shows a schematic of a piston pump according to the invention.
- the piston 1 illustrated in FIG. 1 is accommodated in an axially movable manner in a cylinder 2 . At one end, the piston 1 protrudes from the cylinder 2 , while the other end of the cylinder 2 is of closed design by virtue of a base 3 , which is an integral part of the cylinder 2 .
- the piston 1 encloses an accumulator chamber 4 in the cylinder 2 between it and the base 3 .
- the piston 1 can be driven by means of an eccentric 5 , which can be driven in rotation about an eccentric axis of rotation by means of an electric motor (not shown), so as to perform an axially reciprocating stroke motion in the cylinder 2 .
- an electric motor not shown
- the piston 1 alternately increases and reduces a volume of the accumulator chamber 4 , with the result that fluid is alternately taken up and discharged.
- a piston return spring 6 Arranged in the accumulator chamber 4 is a piston return spring 6 , which is supported on the base 3 of the cylinder 2 and presses against the piston 1 in the axial direction via a spring holder 7 and holds the end of the piston which protrudes from the cylinder 2 in contact with a circumference of the eccentric 5 .
- the spring holder 7 is a deep drawn part made of sheet metal, which is in the form of a shallow dish and has a broad flange-like rim 8 , against which the piston return spring 6 presses.
- the spring holder 7 is mounted on a coaxial extension 9 of reduced diameter of the piston 1 , said extension being an integral part of the piston 1 .
- a sealing ring 11 and a support ring 12 are mounted on the extension 9 of the piston 1 between the rim 8 of the spring holder 7 and an annular shoulder 10 of the piston 1 at the transition to the extension 9 .
- the sealing ring 11 is arranged on a side of the support ring 12 which faces the accumulator chamber 4 .
- the support ring 12 illustrated in FIG. 2 has a square ring cross section with chamfers 13 on an inner side of the support ring 12 .
- the support ring 12 On the outer circumference, the support ring 12 has three longitudinal grooves 14 as longitudinal passages for fluid.
- the support ring 12 rests against the cylinder 2 and, on the inside, rests against the extension 9 of the piston 1 .
- It is composed of a rigid material, e.g. of a PTFE (polytetrafluoroethylene) or a polyamide, such as PA 6.6, and can contain carbon.
- the sealing ring 11 has a rectangular ring cross section, likewise with chamfers 15 on the inside, and an encircling bead 16 on the outer circumference.
- a crest 17 of the bead 16 rests in a sealing manner on the cylinder 2 .
- the crest 17 is that region of the bead 16 which is furthest out radially and, in the embodiment illustrated, the crest 17 is rounded.
- the crest 17 is an encircling feature, like the bead 16 .
- the sealing ring 11 is composed of a flexible material, e.g. an elastomer such as EPDM (ethylene propylene diene rubber).
- FIG. 4 shows, in schematic form, a multi-piston pump 18 according to the invention, which has the piston 1 and the cylinder 2 from FIG. 1 .
- the multi-piston pump 18 is intended for hydraulic vehicle brake systems, e.g. as a return pump in a vehicle brake system with an antilock, traction control and/or vehicle dynamics or antiskid control system. Customary abbreviations for such control systems are ABS, ASR, FDR and/or ESP.
- EHB electro-hydraulic vehicle brake systems
- EHB electro-hydraulic vehicle brake systems
- These are power brake systems, in which the service brake pressure required for braking is produced by means of a piston pump which is part of an independent energy supply device.
- the multi-piston pump 18 is provided for a brake circuit.
- the multi-piston pump 18 has three pistons 1 , 19 , which are arranged in a star shape around the eccentric 5 , part of which is also shown in FIG. 1 .
- the pistons 1 , 19 are accommodated in an axially movable manner in cylinders 2 , 20 , which are inserted into pump bores in a hydraulic block (not shown).
- the hydraulic block contains further hydraulic components, such as hydraulic accumulators and solenoid valves of a slip control system, which are connected hydraulically by bores, which form brake fluid lines.
- the hydraulic block is not shown in the drawing; it is a known feature of slip control devices of this kind.
- the piston 1 and the cylinder 2 from FIG. 1 are illustrated schematically at the bottom in FIG. 4 .
- the eccentric 5 can be driven in rotation by means of an electric motor (not shown in the drawing) about an axis of rotation 22 , with respect to which the eccentric 5 is eccentric.
- an electric motor not shown in the drawing
- the eccentric 5 moves on an orbital path around the axis of rotation 22 .
- the axis of rotation 22 is located at a point of intersection between imaginary longitudinal axes of the pistons 1 , 19 .
- Piston return springs 6 , 23 which hold the pistons 1 , 19 in contact with the circumference of the eccentric 5 , are arranged in the cylinders 2 , 20 , at the ends of the pistons 1 , 19 facing away from the eccentric 5 .
- the eccentric 5 drives the pistons 1 , 19 so that they perform reciprocating stroke motions in the cylinders 2 , 20 .
- the two pistons 19 illustrated at the top in FIG. 4 have a fluid control system, which comprises an inlet valve 24 and an outlet valve 25 .
- the inlet valves 24 are integrated into the pistons 19 , although this is not absolutely essential.
- the valves 24 , 25 are designed as check valves and control the direction of flow of brake fluid.
- Brake fluid flows radially through a transverse hole into the pistons 19 and then through an axial hole through the inlet valve 24 , which is integrated into the pistons 19 , into a pump chamber in the cylinder 20 .
- the brake fluid flows out of the pump chamber through the outlet valve 25 .
- the flow and delivery of brake fluid in piston pumps is known.
- the two pump pistons 19 which have the fluid control system comprising the inlet valves 24 and the outlet valves 25 are referred to below as pump pistons 19 .
- the inlets 26 thereof are interconnected, as are the outlets thereof, which form a common outlet 27 of the multi-piston pump 18 .
- Both pump pistons 19 are arranged in a V arrangement with an angular offset of, for example, 90°. This results in a phase shift in the delivery flows of the two pump pistons 19 , likewise of 90°, and a pulsating flow of brake fluid in the outlet 27 .
- the third piston 1 which corresponds to the piston 1 from FIG. 1 , is referred to below as compensating piston 1 , and it has no valves and no fluid control system. It is arranged on an angle bisector of the two pump pistons 19 and is arranged opposite the two pump pistons 19 , relative to the eccentric 5 , resulting overall in the star arrangement of the pistons 1 , 19 . By virtue of the arrangement on the angle bisector, opposite the two pump pistons 19 , the compensating piston 1 pumps in phase opposition to the common delivery flow of the two pump pistons 19 .
- the compensating piston 1 has just one connection 28 , which is connected to the outlet 27 , i.e. the compensating piston 1 communicates with the two pump pistons 19 .
- connection 28 is routed through intersecting radial holes 29 in the cylinder 2 of the compensating piston 1 (cf. FIG. 1 ).
- the compensating piston 1 alternately draws in brake fluid from the outlet 27 and then displaces the brake fluid volume drawn in back into the outlet 27 .
- the compensating piston 1 is driven in phase opposition to the two pump pistons 19 , the compensating piston 1 draws in brake fluid when the delivery flow of the pump pistons 19 is large.
- the compensating piston 1 displaces brake fluid, with the result that the multi-piston pump 18 according to the invention has a delivery flow at the outlet 27 even when the two pump pistons 19 are not delivering during the return stroke.
- the compensating piston 1 thus reduces the maximum delivery flow of the pump pistons 19 and increases or brings about a delivery flow when the two pump pistons 19 are delivering little or nothing.
- a pressure pulsation of the multi-piston pump 18 is reduced and is approximately equal to a pressure pulsation of a comparable multi-piston pump which has four pump pistons with fluid control.
- a piston area of the pump pistons 19 is larger by a factor of ⁇ 2 than a piston area of the compensating piston 1 .
- the same stroke is obtained by driving all the pistons 1 , 19 with the common eccentric 5 .
- the longitudinal grooves 14 of the support ring 12 avoid a pressure buildup between the sealing ring 11 and the support ring 12 due to “drag leakage” past the sealing ring 11 during a stroke motion of the piston 1 .
- Drag leakage is caused by brake fluid which adheres to the cylinder 2 as a lubricating film and, during the stroke of the piston 1 in the direction of the accumulator chamber 4 , is overridden by the sealing ring 11 and by the support ring 12 , and a small part of which is scraped off during a return stroke in the opposite direction.
- the encircling bead 16 with the encircling crest 17 resting in a sealing manner on the cylinder 2 leads to a good sealing effect.
- the comparatively massive encircling bead 16 imparts a comparatively high stability to the sealing ring 11 , which is composed of a flexible material, thus ensuring that the sealing ring 11 withstands even the high pressures which are produced with the multi-piston pump 18 in a hydraulic vehicle brake system.
- the pump pistons 19 can have an extension 2 , on which a sealing ring 11 and a support ring 12 are arranged, as illustrated in FIGS. 1 to 3 and explained above with reference to said figures.
- the space enclosed in the cylinders 2 , 20 by the pistons 1 , 19 is referred to as a pump chamber in the case of the pump pistons 19 and as an accumulator chamber 4 in the case of the compensating piston 1 .
Abstract
A support ring of a sealing ring of a piston pump of a slip-controlled vehicle brake system is designed with longitudinal grooves in order to prevent a pressure build-up between the sealing ring and the support ring due to slip leakage.
Description
- The invention relates to a piston pump for a hydraulic vehicle brake system having a slip control system, the brake system having the features of the preamble of
claim 1. Slip control systems for vehicle brake systems are known and they are generally implemented as antilock (brake), traction control and/or vehicle dynamics or antiskid control systems. Customary abbreviations are ABS, ASR, FDR and ESP. The piston pumps are used to build up a hydraulic pressure for slip control and are often referred to as return pumps. The piston pump can also be used to build up a hydraulic pressure in a vehicle brake system which employs an independent hydraulic energy source. - Piston pumps for slip-controlled vehicle brake systems are known. They have a cylinder and a piston, which can be moved axially in the cylinder and can be driven so as to perform an axially reciprocating stroke motion in the cylinder. In many cases, the cylinder or cylinders of piston pumps for slip control systems of vehicle brake systems are designed as cylindrical bores in a “hydraulic block”, which, in addition to the piston pump, contains further hydraulic components for slip control, such as solenoid valves, hydraulic accumulators and check valves, and connects them hydraulically. In many cases, the stroke motion is imparted to the piston of such piston pumps by an eccentric, which can be driven in rotation by means of an electric motor and on the circumference of which the piston rests by means of an end face. A piston return spring, which is arranged at an end of the piston facing away from the eccentric, holds the piston end face that faces the eccentric in contact with a circumference of the eccentric.
- The pistons of known piston pumps are sealed off in the cylinder by means of a sealing ring, which is supported axially on a side facing away from a pump chamber by a support ring. The pump chamber is a space in the cylinder, the volume of which is increased and reduced alternately during the reciprocating stroke motion of the piston in order alternately to draw in and displace brake fluid, i.e. to deliver brake fluid. The pump chamber is situated at the end of the piston facing away from the eccentric. The sealing ring is generally composed of a rubber-elastic material, while the support ring is composed of a rigid plastic, the intention being that it should be deformed only slightly, if at all, when subjected to pressure. The function of the support ring is to provide axial support for the sealing ring, preferably over as large an area as possible, in order to avoid extrusion of the sealing ring into a gap when subjected to pressure. In piston pumps for slip control in hydraulic vehicle brake systems, pressures of up to 280 bar, for example, can occur and act on the sealing ring. Extrusion into a gap means flowing, i.e. plastic, deformation of the sealing ring into a gap between the piston and the cylinder. The sealing ring is subjected to pressure on the side facing the pump chamber, and the sealing ring is supported by the support ring on the opposite side, i.e. the side facing away from the pump chamber.
- According to the invention, the support ring has at least one longitudinal passage for fluid, i.e. for brake fluid. By means of the longitudinal passage, the side of the support ring facing the sealing ring communicates with the side thereof facing away from the sealing ring. As a result, a pressure buildup between the sealing ring and the support ring is avoided, with a pressure between the sealing ring and the support ring being relieved via the longitudinal passage. A pressure between the sealing ring and the support ring can arise as a “drag pressure” when there is drag leakage between the sealing ring and the cylinder during the stroke motion of the piston in the cylinder. A pressure buildup between the sealing ring and the support ring would shift the sealing ring away from the support ring and, as already explained, is avoided by means of the at least one longitudinal passage in the support ring.
- The sealing ring and the support ring are usually arranged on the piston, i.e. move with the piston. The opposite situation, in which the sealing ring and the support ring are arranged in the cylinder and are stationary with the latter, is also conceivable.
- The advantage of the invention is the possibility of relatively large-area axial support of the sealing ring by the support ring over an annular area with an outside diameter which corresponds to an inside diameter of the cylinder and with an inside diameter which corresponds to an outside diameter of the piston, in each case at the location where the sealing ring and the support ring are situated. Only the cross section of the at least one longitudinal passage, at the mouth thereof facing the sealing ring, does not participate in the supporting cross-sectional area.
- The dependent claims relate to advantageous embodiments and developments of the invention indicated in
claim 1. - The design of the longitudinal passage as a longitudinal groove on an outer or inner circumference of the support ring as claimed in
claim 2 has the advantage that the support ring is simple to produce in comparison, for example, with a through hole through the support ring, which would likewise be possible as a longitudinal passage. -
Claim 3 provides the support ring according to the invention on a “compensating piston”. Said piston is driven like a pump piston by means of an eccentric, in particular by means of the same eccentric as the pump piston or pistons, but said compensating piston and the cylinder thereof do not have any fluid control, i.e. in particular, do not have either inlet or outlet valves. The compensating piston communicates with the pump piston or pistons of the piston pump and reduces the pressure pulsation thereof. With its cylinder, it can be understood as a hydraulic accumulator, the volume of which varies in synchronism with the stroke motion of the pump piston or pump pistons. The compensating piston and the cylinder thereof do not require a separate inlet and outlet, one connection being sufficient, although separate inlets and outlets are not excluded. - Claim 4 provides an encircling bead on an outside and/or inside of the sealing ring, the crest of which bead rests in a sealing manner on the cylinder and/or the piston.
- The word “crest” refers to the “highest” part of the bead, i.e. the part of the bead which runs around at a point radially furthest toward the outside or furthest toward the inside, and, according to
claim 5, the encircling bead is preferably formed on a sealing ring with an otherwise quadrilateral ring cross section. The quadrilateral basic shape of the ring cross section makes it possible to achieve high resistance to pressure by the sealing ring, with the sealing ring being comparatively massive. The design of the sealing region of the sealing ring as a bead likewise allows relatively massive design and hence high resistance to pressure. The importance of resistance to pressure, especially of the sealing region of the sealing ring, is not exclusively in avoiding destruction of the sealing ring but also in keeping deformation of the sealing region to such a low level, when pressure is imposed from one side, that the sealing effect is as far as possible unimpaired. Another advantage of the sealing ring designed in accordance with the invention is the pressure activation thereof: when subjected to pressure, the sealing ring is compressed axially and expands radially outward and/or inward, resulting in an increase in a contact force on the cylinder and/or the piston. A good sealing effect, both at low pressure and high pressure is thus achieved, and it is possible for the contact force at low pressure to be low in order to reduce friction and wear. -
Claim 6 provides a cylinder closed at one end. This has the advantage that the end of the cylinder does not have to be closed by means of a separate component. - The invention is explained in greater detail below with reference to an embodiment illustrated in the drawing, in which:
-
FIG. 1 shows a piston and a cylinder in accordance with the invention in an axially sectioned view; -
FIG. 2 shows a support ring according to the invention for the piston inFIG. 1 in a perspective view; -
FIG. 3 shows a sealing ring according to the invention for the piston fromFIG. 1 in a perspective half section; and -
FIG. 4 shows a schematic of a piston pump according to the invention. - The
piston 1 illustrated inFIG. 1 is accommodated in an axially movable manner in acylinder 2. At one end, thepiston 1 protrudes from thecylinder 2, while the other end of thecylinder 2 is of closed design by virtue of abase 3, which is an integral part of thecylinder 2. Thepiston 1 encloses an accumulator chamber 4 in thecylinder 2 between it and thebase 3. - The
piston 1 can be driven by means of an eccentric 5, which can be driven in rotation about an eccentric axis of rotation by means of an electric motor (not shown), so as to perform an axially reciprocating stroke motion in thecylinder 2. During the reciprocating stroke motion, thepiston 1 alternately increases and reduces a volume of the accumulator chamber 4, with the result that fluid is alternately taken up and discharged. - Arranged in the accumulator chamber 4 is a
piston return spring 6, which is supported on thebase 3 of thecylinder 2 and presses against thepiston 1 in the axial direction via aspring holder 7 and holds the end of the piston which protrudes from thecylinder 2 in contact with a circumference of the eccentric 5. Thespring holder 7 is a deep drawn part made of sheet metal, which is in the form of a shallow dish and has a broad flange-like rim 8, against which the piston returnspring 6 presses. Thespring holder 7 is mounted on acoaxial extension 9 of reduced diameter of thepiston 1, said extension being an integral part of thepiston 1. Asealing ring 11 and asupport ring 12 are mounted on theextension 9 of thepiston 1 between the rim 8 of thespring holder 7 and anannular shoulder 10 of thepiston 1 at the transition to theextension 9. The sealingring 11 is arranged on a side of thesupport ring 12 which faces the accumulator chamber 4. - The
support ring 12 illustrated inFIG. 2 has a square ring cross section withchamfers 13 on an inner side of thesupport ring 12. On the outer circumference, thesupport ring 12 has threelongitudinal grooves 14 as longitudinal passages for fluid. On the outside, thesupport ring 12 rests against thecylinder 2 and, on the inside, rests against theextension 9 of thepiston 1. It is composed of a rigid material, e.g. of a PTFE (polytetrafluoroethylene) or a polyamide, such as PA 6.6, and can contain carbon. - As can be seen in
FIG. 3 , the sealingring 11 has a rectangular ring cross section, likewise withchamfers 15 on the inside, and an encirclingbead 16 on the outer circumference. Acrest 17 of thebead 16 rests in a sealing manner on thecylinder 2. Thecrest 17 is that region of thebead 16 which is furthest out radially and, in the embodiment illustrated, thecrest 17 is rounded. Thecrest 17 is an encircling feature, like thebead 16. The sealingring 11 is composed of a flexible material, e.g. an elastomer such as EPDM (ethylene propylene diene rubber). -
FIG. 4 shows, in schematic form, amulti-piston pump 18 according to the invention, which has thepiston 1 and thecylinder 2 fromFIG. 1 . Themulti-piston pump 18 is intended for hydraulic vehicle brake systems, e.g. as a return pump in a vehicle brake system with an antilock, traction control and/or vehicle dynamics or antiskid control system. Customary abbreviations for such control systems are ABS, ASR, FDR and/or ESP. Another possible use for themulti-piston pump 18 is in electro-hydraulic vehicle brake systems (abbreviated to EHB). These are power brake systems, in which the service brake pressure required for braking is produced by means of a piston pump which is part of an independent energy supply device. Themulti-piston pump 18 is provided for a brake circuit. - The
multi-piston pump 18 has threepistons FIG. 1 . Thepistons cylinders cylinders piston 1 and thecylinder 2 fromFIG. 1 are illustrated schematically at the bottom inFIG. 4 . - The eccentric 5 can be driven in rotation by means of an electric motor (not shown in the drawing) about an axis of
rotation 22, with respect to which the eccentric 5 is eccentric. When driven in rotation, the eccentric 5 moves on an orbital path around the axis ofrotation 22. The axis ofrotation 22 is located at a point of intersection between imaginary longitudinal axes of thepistons - Piston return springs 6, 23, which hold the
pistons cylinders pistons pistons cylinders - The two
pistons 19 illustrated at the top inFIG. 4 have a fluid control system, which comprises aninlet valve 24 and anoutlet valve 25. Theinlet valves 24 are integrated into thepistons 19, although this is not absolutely essential. Thevalves pistons 19 and then through an axial hole through theinlet valve 24, which is integrated into thepistons 19, into a pump chamber in thecylinder 20. The brake fluid flows out of the pump chamber through theoutlet valve 25. The flow and delivery of brake fluid in piston pumps is known. The twopump pistons 19 which have the fluid control system comprising theinlet valves 24 and theoutlet valves 25 are referred to below aspump pistons 19. Theinlets 26 thereof are interconnected, as are the outlets thereof, which form acommon outlet 27 of themulti-piston pump 18. - Both
pump pistons 19 are arranged in a V arrangement with an angular offset of, for example, 90°. This results in a phase shift in the delivery flows of the twopump pistons 19, likewise of 90°, and a pulsating flow of brake fluid in theoutlet 27. - The
third piston 1, which corresponds to thepiston 1 fromFIG. 1 , is referred to below as compensatingpiston 1, and it has no valves and no fluid control system. It is arranged on an angle bisector of the twopump pistons 19 and is arranged opposite the twopump pistons 19, relative to the eccentric 5, resulting overall in the star arrangement of thepistons pump pistons 19, the compensatingpiston 1 pumps in phase opposition to the common delivery flow of the twopump pistons 19. The compensatingpiston 1 has just oneconnection 28, which is connected to theoutlet 27, i.e. the compensatingpiston 1 communicates with the twopump pistons 19. Theconnection 28 is routed through intersecting radial holes 29 in thecylinder 2 of the compensating piston 1 (cf.FIG. 1 ). During its stroke motion, the compensatingpiston 1 alternately draws in brake fluid from theoutlet 27 and then displaces the brake fluid volume drawn in back into theoutlet 27. Since the compensatingpiston 1 is driven in phase opposition to the twopump pistons 19, the compensatingpiston 1 draws in brake fluid when the delivery flow of thepump pistons 19 is large. When thepump pistons 19 are not delivering any brake fluid during their return stroke, the compensatingpiston 1 displaces brake fluid, with the result that themulti-piston pump 18 according to the invention has a delivery flow at theoutlet 27 even when the twopump pistons 19 are not delivering during the return stroke. The compensatingpiston 1 thus reduces the maximum delivery flow of thepump pistons 19 and increases or brings about a delivery flow when the twopump pistons 19 are delivering little or nothing. A pressure pulsation of themulti-piston pump 18 is reduced and is approximately equal to a pressure pulsation of a comparable multi-piston pump which has four pump pistons with fluid control. - For the same stroke, a piston area of the
pump pistons 19 is larger by a factor of √2 than a piston area of the compensatingpiston 1. The same stroke is obtained by driving all thepistons common eccentric 5. - The
longitudinal grooves 14 of thesupport ring 12 avoid a pressure buildup between the sealingring 11 and thesupport ring 12 due to “drag leakage” past the sealingring 11 during a stroke motion of thepiston 1. Drag leakage is caused by brake fluid which adheres to thecylinder 2 as a lubricating film and, during the stroke of thepiston 1 in the direction of the accumulator chamber 4, is overridden by the sealingring 11 and by thesupport ring 12, and a small part of which is scraped off during a return stroke in the opposite direction. The encirclingbead 16 with the encirclingcrest 17 resting in a sealing manner on thecylinder 2 leads to a good sealing effect. The comparatively massiveencircling bead 16 imparts a comparatively high stability to the sealingring 11, which is composed of a flexible material, thus ensuring that the sealingring 11 withstands even the high pressures which are produced with themulti-piston pump 18 in a hydraulic vehicle brake system. - Like the compensating
piston 1, thepump pistons 19 can have anextension 2, on which asealing ring 11 and asupport ring 12 are arranged, as illustrated inFIGS. 1 to 3 and explained above with reference to said figures. The space enclosed in thecylinders pistons pump pistons 19 and as an accumulator chamber 4 in the case of the compensatingpiston 1.
Claims (6)
1. A piston pump for a hydraulic vehicle brake system having a slip control system, comprising:
a cylinder defining an accumulator or pump chamber,
a piston configured to be moved axially in the cylinder and driven so as to perform an axially reciprocating stroke motion in the cylinder,
a sealing ring configured to seal off the piston in the cylinder, and
a support ring arranged on a side of the sealing ring facing away from the accumulator or pump chamber and configured to support the sealing ring axially on the side facing away from the accumulator or pump chamber,
wherein the support ring has at least one longitudinal passage for fluid.
2. The piston pump as claimed in claim 1 , wherein the support ring has at least one longitudinal groove as a longitudinal passage.
3. The piston pump as claimed in claim 1 , wherein:
the piston is a compensating piston configured to reduce a pressure pulsation of the piston pump, said piston communicating with at least one pump piston of the piston pump, and
the piston and the cylinder do not have any fluid control.
4. The piston pump as claimed in claim 1 , wherein the sealing ring has an encircling bead on the outside and/or the inside thereof, the crest of which rests in a sealing manner on the cylinder and/or the piston.
5. The piston pump as claimed in claim 4 , wherein the sealing ring has a quadrilateral ring cross section with the encircling bead on the outside and/or the inside.
6. The piston pump as claimed in claim 1 , wherein the cylinder has a closed end.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102009047217A DE102009047217A1 (en) | 2009-11-27 | 2009-11-27 | Crude piston |
DE102009047217.7 | 2009-11-27 | ||
PCT/EP2010/064438 WO2011064019A2 (en) | 2009-11-27 | 2010-09-29 | Piston pump |
Publications (1)
Publication Number | Publication Date |
---|---|
US20130121861A1 true US20130121861A1 (en) | 2013-05-16 |
Family
ID=43926969
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/512,022 Abandoned US20130121861A1 (en) | 2009-11-27 | 2010-09-29 | Piston Pump |
Country Status (7)
Country | Link |
---|---|
US (1) | US20130121861A1 (en) |
EP (1) | EP2504577B1 (en) |
JP (1) | JP5576941B2 (en) |
KR (1) | KR20120099062A (en) |
CN (1) | CN102630278A (en) |
DE (1) | DE102009047217A1 (en) |
WO (1) | WO2011064019A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016070239A (en) * | 2014-09-30 | 2016-05-09 | 日信工業株式会社 | Solenoid pump |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102011079860A1 (en) * | 2011-07-26 | 2013-01-31 | Robert Bosch Gmbh | A braking system for a vehicle and method for operating a braking system of a vehicle |
DE102012203931A1 (en) * | 2011-08-02 | 2013-02-07 | Continental Teves Ag & Co. Ohg | piston pump |
DE102012201240B4 (en) * | 2012-01-30 | 2023-03-16 | Bayerische Motoren Werke Aktiengesellschaft | Seal for fuel pump |
CN103062041A (en) * | 2012-12-06 | 2013-04-24 | 西安航空动力控制科技有限公司 | Lining sleeve of cylinder block |
DE102012223107A1 (en) * | 2012-12-13 | 2014-06-18 | Robert Bosch Gmbh | Pump seal of a piston pump of a vehicle brake system |
ITMO20120313A1 (en) * | 2012-12-20 | 2014-06-21 | Leuco Spa | PISTON PUMP. |
KR102214605B1 (en) * | 2014-10-13 | 2021-02-10 | 현대모비스 주식회사 | Piston pump of brake system for vehicle |
KR102390510B1 (en) * | 2017-07-31 | 2022-04-26 | 현대모비스 주식회사 | Pump device for electronic control brake system |
JP6635560B1 (en) * | 2018-09-20 | 2020-01-29 | 谷口 秀夫 | Hot end of modeling material for 3D modeling apparatus and 3D modeling apparatus equipped with hot end |
JP7025085B2 (en) * | 2019-08-27 | 2022-02-24 | 秀夫 谷口 | Hot end of modeling material for 3D modeling device, and 3D modeling device equipped with hot end |
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- 2009-11-27 DE DE102009047217A patent/DE102009047217A1/en not_active Withdrawn
-
2010
- 2010-09-29 JP JP2012540334A patent/JP5576941B2/en not_active Expired - Fee Related
- 2010-09-29 KR KR1020127013628A patent/KR20120099062A/en not_active Application Discontinuation
- 2010-09-29 WO PCT/EP2010/064438 patent/WO2011064019A2/en active Application Filing
- 2010-09-29 EP EP10759649.6A patent/EP2504577B1/en active Active
- 2010-09-29 US US13/512,022 patent/US20130121861A1/en not_active Abandoned
- 2010-09-29 CN CN2010800534564A patent/CN102630278A/en active Pending
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Also Published As
Publication number | Publication date |
---|---|
EP2504577B1 (en) | 2013-11-20 |
KR20120099062A (en) | 2012-09-06 |
JP2013511432A (en) | 2013-04-04 |
JP5576941B2 (en) | 2014-08-20 |
WO2011064019A3 (en) | 2012-02-23 |
EP2504577A2 (en) | 2012-10-03 |
DE102009047217A1 (en) | 2011-06-01 |
CN102630278A (en) | 2012-08-08 |
WO2011064019A2 (en) | 2011-06-03 |
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Legal Events
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AS | Assignment |
Owner name: ROBERT BOSCH GMBH, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SCHEPP, RENE;SCHMOLL, KLAUS-PETER;ALAZE, NORBERT;AND OTHERS;SIGNING DATES FROM 20120903 TO 20120924;REEL/FRAME:029222/0825 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |