US20030205283A1 - Fluid accumulator for use in a vehicle anti-lock brake system - Google Patents
Fluid accumulator for use in a vehicle anti-lock brake system Download PDFInfo
- Publication number
- US20030205283A1 US20030205283A1 US09/969,543 US96954301A US2003205283A1 US 20030205283 A1 US20030205283 A1 US 20030205283A1 US 96954301 A US96954301 A US 96954301A US 2003205283 A1 US2003205283 A1 US 2003205283A1
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- United States
- Prior art keywords
- grommet
- shaft
- accumulator
- piston
- axial
- 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.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
- F15B1/02—Installations or systems with accumulators
- F15B1/04—Accumulators
- F15B1/08—Accumulators using a gas cushion; Gas charging devices; Indicators or floats therefor
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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
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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
- B60T8/36—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 including a pilot valve responding to an electromagnetic force
- B60T8/3615—Electromagnetic valves specially adapted for anti-lock brake and traction control systems
- B60T8/3675—Electromagnetic valves specially adapted for anti-lock brake and traction control systems integrated in modulator units
- B60T8/368—Electromagnetic valves specially adapted for anti-lock brake and traction control systems integrated in modulator units combined with other mechanical components, e.g. pump units, master cylinders
- B60T8/3685—Electromagnetic valves specially adapted for anti-lock brake and traction control systems integrated in modulator units combined with other mechanical components, e.g. pump units, master cylinders characterised by the mounting of the modulator unit onto the vehicle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2201/00—Accumulators
- F15B2201/20—Accumulator cushioning means
- F15B2201/21—Accumulator cushioning means using springs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2201/00—Accumulators
- F15B2201/30—Accumulator separating means
- F15B2201/31—Accumulator separating means having rigid separating means, e.g. pistons
- F15B2201/312—Sealings therefor, e.g. piston rings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2201/00—Accumulators
- F15B2201/40—Constructional details of accumulators not otherwise provided for
- F15B2201/41—Liquid ports
- F15B2201/413—Liquid ports having multiple liquid ports
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S303/00—Fluid-pressure and analogous brake systems
- Y10S303/11—Accumulator
Definitions
- the present invention relates generally to a low pressure accumulator and more particularly, to a low pressure accumulator assembly for receiving and temporarily storing fluid in a vehicle anti-lock brake system.
- prior art anti-lock brake systems include a central control unit for monitoring the speed of the controlled wheels to determine the deceleration of the controlled wheels.
- the central control unit functions to control the application of hydraulic pressure through a control valve means to the associated brakes to prevent lockup of the controlled wheels.
- the anti-lock brake system includes means for cyclically reducing and reapplying pressure to the associated brakes to limit wheel slippage to a safe level while continuing to produce adequate brake torque to decelerate the vehicle as desired by the driver.
- a low pressure accumulator which is operative to temporarily receive and store brake fluid during pressure reduction phases of the anti-lock operation.
- the low pressure accumulator typically maintains fluid stored therein at a predetermined minimum pressure determined by a compression spring acting on an accumulator piston, generally in the range of 30-60 p.s.i. This minimum pressure represents the lowest pressure to which the controlled brakes can be reduced during anti-lock operation.
- U.S. Pat. No. 4,976,501 incorporated herein by reference, describes an accumulator which maintains brake fluid stored therein at or near zero pressure. Thus, if necessary, fluid pressure to the controlled wheel brakes can be reduced to near zero pressure.
- Each low pressure accumulator 102 includes a generally cup-shaped piston 104 slidably received within an axial bore 106 of a hydraulic control unit (HCU) 108 of a braking system.
- An end cap 110 is sealingly mounted at an open end of the bore 106 .
- the end cap 1 10 includes an aperture for receiving an elastomeric boot 112 .
- the elastomeric boot 112 is generally cup shaped and has a closed end and an open end. The open end includes an inwardly extending flange for attaching to a lip portion (not shown) formed about the aperture of the end cap 110 .
- the boot 112 may include a passageway, such as a narrow slit, for the passage of air in the closed end thereof.
- a passageway such as a narrow slit
- the elastomeric boot 112 allows a small volume of air to flow between the boot 112 and the end cap 110 as the piston moves from a top dead center to a bottom dead center position.
- the flow of air is further facilitated in boots 112 having a narrow slit in the closed end.
- the very small opening between the boot 112 and the end cap 110 further inhibits, but does not eliminate, the flow of water or contaminants into the accumulator.
- the boot 112 thereby allows for the passage of air as the piston 104 moves and provides an environmental seal which prevents water and contaminants from entering the accumulator 102 .
- Conventional braking system hydraulic control units are typically mounted to vehicle frame by a plurality of bolts. Elastomeric grommets are typically mounted between each bolt and the frame to absorb vibrations. Such conventional braking system hydraulic control units typically require three or more mounting bolts and associated elastomeric grommets, washers, and nuts.
- the invention relates to a fluid accumulator, especially a low pressure fluid accumulator of a hydraulic control unit of a vehicle brake system.
- the accumulator body has an inner surface defining an axial bore extending from an open end to a closed end of the accumulator body.
- a generally cup-shaped cylindrical piston has an inner surface defining an axial bore and extends from an open end to a closed end of the piston, and is slidably received within the axial bore of the accumulator body.
- a cap has a generally cylindrical body portion and an inner surface defining an axial passageway therethrough. A circumferential, radially outwardly extending flange is formed on one end of the body portion of the cap.
- the cap is mounted in the bore of the accumulator body with the outer edge of the flange of the cap pressed into or otherwise fixed relative to the bore of the accumulator body and retains the piston therein.
- a spring is disposed between the cap and the piston and urges the piston relatively away from the cap and toward the closed end of the accumulator body.
- a grommet has a shaft and an enlarged annular head formed on a first end of the shaft. The shaft is disposed to seal against the inner surface of the cap.
- the grommet has an inner surface defining an axial bore extending from the head through an open end of the shaft at the first end of the shaft to a closed end of said shaft at a second end of the shaft, the closed end of said shaft having a closable passageway therethrough.
- the low pressure accumulator of the invention provides an advantageous integration of the mounting of a braking system hydraulic control unit, and venting of a low pressure accumulator into one component. Assembly of a hydraulic control unit within a vehicle is simplified because, for example, one or more fasteners, such as a bolt and an associated grommet, washer, and nut, is eliminated. Further, the mechanical features of the grommet create a “dual-rate” effect that is more compliant for low amplitude vibration.
- FIG. 1 is an elevational view, partially in cross section, of a pair of low pressure accumulators as known in the prior art including a rubber boot.
- FIG. 2 is an elevational view in cross section of a low pressure accumulator in accordance with this invention with the components of the accumulator shown in position after the introduction of fluid into the accumulator reservoir.
- FIG. 3 is a perspective view of the grommet of FIG. 2.
- FIG. 4 is an end view of the grommet taken along line 4 - 4 of FIG. 2.
- the low pressure accumulator 14 includes a body 34 .
- the body 34 typically forms a portion of a hydraulic control unit (HCU) of a brake system.
- the body 34 has an axial bore 36 extending from an open end 38 to a closed end 40 .
- the closed end 40 of the bore 36 includes one or more apertures 42 for providing fluid communication between the bore 36 and the brake lines of the brake system in which the accumulator is installed.
- a generally cup-shaped cylindrical piston 45 has an inner surface defining an axial bore 46 extending from an open end 47 to a closed end 48 of the piston 45 .
- the piston 45 is slidably received within the axial bore 36 of the body 34 .
- a plurality of generally cylindrical bosses 49 extend axially from an outer surface 50 of the closed end 48 .
- the piston 45 and the body 34 cooperate to define an accumulator reservoir 15 .
- a circumferential groove 56 is formed in an outer surface of the piston 45 .
- An O-ring 58 is disposed within the groove 56 for fluidly sealing between the piston 45 and the inner surface of the body 34 defining the axial bore 46 .
- a cap 60 has a generally cylindrical body portion 62 .
- the body portion 62 is generally tubular having an inner surface defining an axial passageway 63 therethrough.
- the body portion 62 further has an inner end 62 a (closest to the closed end 40 of the bore 36 ) and an outer end 62 b .
- a circumferential, radially outwardly extending flange 64 is formed on the outer end 62 b of the body portion 62 .
- the cap 60 is mounted in the bore 36 of the accumulator body 34 to retain the piston 45 in the bore 36 .
- the cap flange 64 is press fit within the open end 38 of the body 34 , however any other suitable form of mounting may be used.
- a helical compression spring 68 is disposed between the cap flange 64 and the closed end 48 of the piston 45 . The spring 68 urges the piston 45 relatively away from the cap flange 64 and toward the closed end 40 of the accumulator body 34 .
- a grommet 70 has a shaft 72 having an inner end 72 a (adjacent the inner end 62 a of the cap 60 ) and an outer end 72 b .
- the grommet 70 may be formed of any suitable material, such as an elastomeric material.
- An enlarged annular head 74 is formed on the outer end 72 b of the shaft 72 .
- the grommet 70 includes an inner surface defining an axial bore 75 extending from an open end at the outer end 72 b of the shaft 72 to a closed end 76 at the inner end 72 a of the shaft 72 .
- the closed end 76 of the shaft 72 has a passageway 78 , such as, for example, a narrow slit, formed therethrough.
- the passageway 78 preferably is urged closed by the surrounding elastomeric material of the grommet 70 .
- a plurality of spaced apart circumferential ribs 80 are formed on an outer surface of the shaft 72 of the grommet 70 .
- the outer diameter of each rib 80 is slightly larger than the inner diameter of the axial passageway 63 of the cap 60 . When inserted into the passageway 63 , the ribs 80 compress radially inwardly and deform to provide a sealing engagement with the axial passageway 63 of the cap 60 .
- a plurality of axial grooves 82 are formed within the axial bore 75 of the grommet 70 . As illustrated in FIG. 2, the grooves 82 extend the entire length of the axial bore 75 , however the grooves 82 may have a length shorter than the length of the bore 75 , as will be explained in detail below.
- the narrow slit 78 provides fluid communication between the axial bore 75 and the enclosed volume 79 between the piston 48 , the cap 60 , and the grommet 70 , to vent the volume 79 and thus allow the piston 48 to move freely.
- the head 74 of the grommet 70 has a diameter larger than the diameter of the shaft 72 .
- the head 74 has a crown cut geometry providing radially extending V-shaped grooves 84 within an axial face of the head 74 .
- the V-shaped grooves 84 are equiangular spaced and extend from an opening of the axial bore 75 of the grommet 70 .
- the base of each groove 84 extends radially outwardly and at an angle a away from the plane p of the axial face of the head 74 (e.g., the plane perpendicular to a longitudinal axis of the axial bore 75 of the grommet).
- each groove 84 is defined by a pair of equiangular spaced ridges 86 on either side thereof. The grooves 84 provide radial fluid communication between the atmosphere and the axial bore 75 of the grommet 70 .
- the axial bore 75 is adapted for mounting on a pin 88 .
- the pin 88 is a steel pin attached to a vehicle chassis 90 .
- the pin 88 is preferably mounted within the bore 75 of the grommet 70 in a line to line fit, however any other suitable mounting method may be used, such as an interference fit.
- the piston 45 is normally biased upwardly (as viewed in FIG. 2) by the compression spring 68 toward the closed end 40 of the accumulator body 34 . In this position, the piston 45 and the body 34 cooperate to define an accumulator reservoir 15 at minimum volume.
- the piston 45 when the brake system enters the anti-lock mode and fluid is dumped into the accumulator reservoir 15 , the piston 45 is shifted downwardly (as viewed in FIG. 2) and compresses the spring 68 .
- the spring 68 urges the piston 45 upwardly (as viewed in FIG. 2) such that the bosses 49 on the surface 50 of the piston 45 are seated against the closed end 40 of the accumulator body 35 to maintain the accumulator reservoir 15 at minimum volume.
- the grommet 70 is adapted to be mounted in the low pressure accumulator 14 of a typical ABS brake system and particularly may be mounted in an HCU arrangement.
- the HCU (not shown) is provided with a plurality of internal openings and passageways formed therein for receiving and interconnecting various components of the ABS, such as, for example, a dump valve, and one or more low pressure accumulator 14 .
- the HCU is typically attached to a vehicle frame by a plurality of bolts, such as, for example three bolts.
- Each bolt typically includes a rubber grommet attached thereto and disposed between the HCU and the vehicle frame to dampen vibrations. Also associated with each bolt are associated washers and nuts.
- the specific construction of the grommet 70 allows the low pressure accumulator 14 to be used as a mounting point to mount the HCU to the vehicle frame.
- the pin 88 is preferably a portion of a mounting bracket and suitably attached to the vehicle chassis 90 . The HCU may therefore be attached to the vehicle chassis 90 by inserting the pin 88 into the bore 75 of the grommet 70 .
- the ridges 86 of the grommet 70 are disposed against the mounting bracket or the vehicle chassis 90 . More specifically, the HCU may be slipped onto the pin 90 (or pins 90 ) associated with each of the low pressure accumulators 14 of the HCU that is provided with an associated grommet 70 to limit movement in two axes. The HCU is prevented from slipping back off of the pin(s) 88 (the third axis of movement) by the use of one or more conventional bolt/nut and grommet arrangement. The use of the low pressure accumulator 14 and its associated grommet 70 as a mounting point thereby reduces the number of mounting bolts and associated rubber grommets, nuts and washers required to mount the HCU to the vehicle chassis 90 and speeds the time required to mount the HCU.
- the novel shape of the grommet 70 also facilitates improved passage of air as the piston 45 moves, and provides an improved environmental seal which prevents water and contaminates from entering the accumulator 14 .
- air is drawn into a cavity between the closed end 76 of the grommet 45 and the closed end 48 of the piston 45 .
- air flows between the grommet 70 and the chassis 90 , through the grooves 84 , through the axial grooves 82 and through the passageway 78 .
- the pin 88 has a length shorter than the length of the bore 75 of the grommet 70 and shorter than the length of the axial grooves 82 , such that air may flow through the grooves 82 from the V-shaped grooves 84 to the slit 78 .
- the novel shape of the grommet 70 provides an improved environmental seal by providing a circuitous path for water and contaminates to flow. Further, the narrow slit 78 is normally closed. Any water or contaminate that may flow through the circuitous path formed by the V-shaped grooves 84 and the axial grooves 82 is prevented from flowing through the normally closed narrow slit 78 , thus providing an improved environmental seal.
- the plurality of narrow ridges 86 provide a reduced contact surface between the grommet 70 and the vehicle chassis 90 .
- the crown-shaped geometry creates a “dual rate” effect that is more compliant for low amplitude vibration. That is, the reduced contact surface allows the grommet 70 to efficiently absorb energy generated by high frequency, low amplitude vibration typically generated by the brake system 10 and prevents the transfer of the energy to the vehicle chassis 90 . Additionally, the reduced contact surface allows the grommet 70 to absorb the energy typically generated by the vibration of the vehicle during travel on a road surface and prevents the transfer of road vibration through the chassis 90 to the brake system 10 .
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Electromagnetism (AREA)
- Transportation (AREA)
- General Engineering & Computer Science (AREA)
- Valves And Accessory Devices For Braking Systems (AREA)
- Regulating Braking Force (AREA)
- Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
Abstract
Description
- The present invention relates generally to a low pressure accumulator and more particularly, to a low pressure accumulator assembly for receiving and temporarily storing fluid in a vehicle anti-lock brake system.
- Braking a vehicle in a controlled manner under adverse conditions such as rain, snow, or ice generally requires precise application of the brakes by the vehicle driver. Under these conditions, or in panic stop situations, a driver will often apply excessive brake pressure, thus causing the wheels to lock such that excessive slippage between the wheels and the road surface takes place. Wheel lockup conditions can lead to loss of directional stability and, possibly, uncontrolled vehicle spinout.
- In a continuing effort to improve the operational safety of vehicles, many companies have been involved in the development of anti-lock braking systems. While typically such systems are adapted to control the braking of each braked wheel of a vehicle, some systems have been developed for controlling the braking of only a portion of the braked wheels. Examples of prior art anti-lock brake systems are disclosed in U.S. Pat. Nos. 3,515,440; 3,731,979; 3,870,376; and 3,880,474 and are herein incorporated by reference.
- Generally, prior art anti-lock brake systems include a central control unit for monitoring the speed of the controlled wheels to determine the deceleration of the controlled wheels. When the brakes of the vehicle are applied and the wheel deceleration of the monitored wheels exceeds a predetermined deceleration threshold, indicating that there is wheel slippage and the wheels are approaching a lockup condition, the central control unit functions to control the application of hydraulic pressure through a control valve means to the associated brakes to prevent lockup of the controlled wheels. Typically, the anti-lock brake system includes means for cyclically reducing and reapplying pressure to the associated brakes to limit wheel slippage to a safe level while continuing to produce adequate brake torque to decelerate the vehicle as desired by the driver. While some systems utilize a separate hydraulic pump as the means for reapplying pressure, other systems, such as disclosed in U.S. Pat. No. 4,418,966, do not require the use of a separate hydraulic pump. U.S. Pat. No. 4,418,966 is herein incorporated by reference.
- In controlling the application of pressure to selected wheel brakes, many systems utilize a low pressure accumulator which is operative to temporarily receive and store brake fluid during pressure reduction phases of the anti-lock operation. The low pressure accumulator typically maintains fluid stored therein at a predetermined minimum pressure determined by a compression spring acting on an accumulator piston, generally in the range of 30-60 p.s.i. This minimum pressure represents the lowest pressure to which the controlled brakes can be reduced during anti-lock operation. However, it has been found that, in certain braking situations, it is necessary to reduce the controlled pressure below this minimum pressure in order to achieve the desired control. U.S. Pat. No. 4,976,501, incorporated herein by reference, describes an accumulator which maintains brake fluid stored therein at or near zero pressure. Thus, if necessary, fluid pressure to the controlled wheel brakes can be reduced to near zero pressure.
- Referring now to FIG. 1, a pair of conventional low pressure accumulators are generally shown at100. Each
low pressure accumulator 102 includes a generally cup-shaped piston 104 slidably received within anaxial bore 106 of a hydraulic control unit (HCU) 108 of a braking system. An end cap 110 is sealingly mounted at an open end of thebore 106. Typically, the end cap 1 10 includes an aperture for receiving anelastomeric boot 112. Theelastomeric boot 112 is generally cup shaped and has a closed end and an open end. The open end includes an inwardly extending flange for attaching to a lip portion (not shown) formed about the aperture of the end cap 110. Theboot 112 may include a passageway, such as a narrow slit, for the passage of air in the closed end thereof. In operation theelastomeric boot 112 allows a small volume of air to flow between theboot 112 and the end cap 110 as the piston moves from a top dead center to a bottom dead center position. The flow of air is further facilitated inboots 112 having a narrow slit in the closed end. The very small opening between theboot 112 and the end cap 110 further inhibits, but does not eliminate, the flow of water or contaminants into the accumulator. Theboot 112 thereby allows for the passage of air as thepiston 104 moves and provides an environmental seal which prevents water and contaminants from entering theaccumulator 102. - Conventional braking system hydraulic control units are typically mounted to vehicle frame by a plurality of bolts. Elastomeric grommets are typically mounted between each bolt and the frame to absorb vibrations. Such conventional braking system hydraulic control units typically require three or more mounting bolts and associated elastomeric grommets, washers, and nuts.
- The invention relates to a fluid accumulator, especially a low pressure fluid accumulator of a hydraulic control unit of a vehicle brake system. The accumulator body has an inner surface defining an axial bore extending from an open end to a closed end of the accumulator body. A generally cup-shaped cylindrical piston has an inner surface defining an axial bore and extends from an open end to a closed end of the piston, and is slidably received within the axial bore of the accumulator body. A cap has a generally cylindrical body portion and an inner surface defining an axial passageway therethrough. A circumferential, radially outwardly extending flange is formed on one end of the body portion of the cap. The cap is mounted in the bore of the accumulator body with the outer edge of the flange of the cap pressed into or otherwise fixed relative to the bore of the accumulator body and retains the piston therein. A spring is disposed between the cap and the piston and urges the piston relatively away from the cap and toward the closed end of the accumulator body. A grommet has a shaft and an enlarged annular head formed on a first end of the shaft. The shaft is disposed to seal against the inner surface of the cap. The grommet has an inner surface defining an axial bore extending from the head through an open end of the shaft at the first end of the shaft to a closed end of said shaft at a second end of the shaft, the closed end of said shaft having a closable passageway therethrough.
- The low pressure accumulator of the invention provides an advantageous integration of the mounting of a braking system hydraulic control unit, and venting of a low pressure accumulator into one component. Assembly of a hydraulic control unit within a vehicle is simplified because, for example, one or more fasteners, such as a bolt and an associated grommet, washer, and nut, is eliminated. Further, the mechanical features of the grommet create a “dual-rate” effect that is more compliant for low amplitude vibration.
- Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
- FIG. 1 is an elevational view, partially in cross section, of a pair of low pressure accumulators as known in the prior art including a rubber boot.
- FIG. 2 is an elevational view in cross section of a low pressure accumulator in accordance with this invention with the components of the accumulator shown in position after the introduction of fluid into the accumulator reservoir.
- FIG. 3 is a perspective view of the grommet of FIG. 2.
- FIG. 4 is an end view of the grommet taken along line4-4 of FIG. 2.
- Referring now to the drawings, there is illustrated in FIG. 2 a low pressure accumulator, generally shown at14. The
low pressure accumulator 14 includes abody 34. Thebody 34 typically forms a portion of a hydraulic control unit (HCU) of a brake system. Thebody 34 has anaxial bore 36 extending from anopen end 38 to a closed end 40. The closed end 40 of thebore 36 includes one ormore apertures 42 for providing fluid communication between thebore 36 and the brake lines of the brake system in which the accumulator is installed. - A generally cup-shaped
cylindrical piston 45 has an inner surface defining anaxial bore 46 extending from anopen end 47 to a closed end 48 of thepiston 45. Thepiston 45 is slidably received within theaxial bore 36 of thebody 34. Preferably, a plurality of generallycylindrical bosses 49 extend axially from anouter surface 50 of the closed end 48. Thepiston 45 and thebody 34 cooperate to define anaccumulator reservoir 15. Acircumferential groove 56 is formed in an outer surface of thepiston 45. An O-ring 58 is disposed within thegroove 56 for fluidly sealing between thepiston 45 and the inner surface of thebody 34 defining theaxial bore 46. - A
cap 60 has a generally cylindrical body portion 62. The body portion 62 is generally tubular having an inner surface defining anaxial passageway 63 therethrough. The body portion 62 further has an inner end 62 a (closest to the closed end 40 of the bore 36) and an outer end 62 b. A circumferential, radially outwardly extendingflange 64 is formed on the outer end 62 b of the body portion 62. Thecap 60 is mounted in thebore 36 of theaccumulator body 34 to retain thepiston 45 in thebore 36. Preferably thecap flange 64 is press fit within theopen end 38 of thebody 34, however any other suitable form of mounting may be used. Ahelical compression spring 68 is disposed between thecap flange 64 and the closed end 48 of thepiston 45. Thespring 68 urges thepiston 45 relatively away from thecap flange 64 and toward the closed end 40 of theaccumulator body 34. - Referring now to FIGS. 2 through 4, a
grommet 70 has ashaft 72 having an inner end 72 a (adjacent the inner end 62 a of the cap 60) and an outer end 72 b. Thegrommet 70 may be formed of any suitable material, such as an elastomeric material. An enlargedannular head 74 is formed on the outer end 72 b of theshaft 72. Thegrommet 70 includes an inner surface defining anaxial bore 75 extending from an open end at the outer end 72 b of theshaft 72 to aclosed end 76 at the inner end 72 a of theshaft 72. Theclosed end 76 of theshaft 72 has apassageway 78, such as, for example, a narrow slit, formed therethrough. Thepassageway 78 preferably is urged closed by the surrounding elastomeric material of thegrommet 70. A plurality of spaced apartcircumferential ribs 80 are formed on an outer surface of theshaft 72 of thegrommet 70. The outer diameter of eachrib 80 is slightly larger than the inner diameter of theaxial passageway 63 of thecap 60. When inserted into thepassageway 63, theribs 80 compress radially inwardly and deform to provide a sealing engagement with theaxial passageway 63 of thecap 60. A plurality ofaxial grooves 82 are formed within the axial bore 75 of thegrommet 70. As illustrated in FIG. 2, thegrooves 82 extend the entire length of theaxial bore 75, however thegrooves 82 may have a length shorter than the length of thebore 75, as will be explained in detail below. Thenarrow slit 78 provides fluid communication between theaxial bore 75 and theenclosed volume 79 between the piston 48, thecap 60, and thegrommet 70, to vent thevolume 79 and thus allow the piston 48 to move freely. - The
head 74 of thegrommet 70 has a diameter larger than the diameter of theshaft 72. Thehead 74 has a crown cut geometry providing radially extending V-shapedgrooves 84 within an axial face of thehead 74. The V-shapedgrooves 84 are equiangular spaced and extend from an opening of theaxial bore 75 of thegrommet 70. The base of eachgroove 84 extends radially outwardly and at an angle a away from the plane p of the axial face of the head 74 (e.g., the plane perpendicular to a longitudinal axis of theaxial bore 75 of the grommet). However, it will be appreciated that satisfactory results may be achieved by grooves having other shapes, such as grooves with a square or arcuate cross-section. Similarly, satisfactory results may be achieved by agrommet 70 wherein the base of each groove extends radially outwardly and at an angle toward the plane of the axial face of thehead 74 or wherein the base of each groove is parallel with the plane of the axial face of thehead 74. Eachgroove 84 is defined by a pair of equiangular spacedridges 86 on either side thereof. Thegrooves 84 provide radial fluid communication between the atmosphere and theaxial bore 75 of thegrommet 70. - The axial bore75 is adapted for mounting on a
pin 88. Preferably, thepin 88 is a steel pin attached to avehicle chassis 90. Thepin 88 is preferably mounted within thebore 75 of thegrommet 70 in a line to line fit, however any other suitable mounting method may be used, such as an interference fit. - The
piston 45 is normally biased upwardly (as viewed in FIG. 2) by thecompression spring 68 toward the closed end 40 of theaccumulator body 34. In this position, thepiston 45 and thebody 34 cooperate to define anaccumulator reservoir 15 at minimum volume. In accordance with the present invention, when the brake system enters the anti-lock mode and fluid is dumped into theaccumulator reservoir 15, thepiston 45 is shifted downwardly (as viewed in FIG. 2) and compresses thespring 68. During non-braking conditions, thespring 68 urges thepiston 45 upwardly (as viewed in FIG. 2) such that thebosses 49 on thesurface 50 of thepiston 45 are seated against the closed end 40 of the accumulator body 35 to maintain theaccumulator reservoir 15 at minimum volume. - An important aspect of the invention is the configuration of the
grommet 70. Thegrommet 70 is adapted to be mounted in thelow pressure accumulator 14 of a typical ABS brake system and particularly may be mounted in an HCU arrangement. The HCU (not shown) is provided with a plurality of internal openings and passageways formed therein for receiving and interconnecting various components of the ABS, such as, for example, a dump valve, and one or morelow pressure accumulator 14. - The HCU is typically attached to a vehicle frame by a plurality of bolts, such as, for example three bolts. Each bolt typically includes a rubber grommet attached thereto and disposed between the HCU and the vehicle frame to dampen vibrations. Also associated with each bolt are associated washers and nuts. The specific construction of the
grommet 70 allows thelow pressure accumulator 14 to be used as a mounting point to mount the HCU to the vehicle frame. Specifically, thepin 88 is preferably a portion of a mounting bracket and suitably attached to thevehicle chassis 90. The HCU may therefore be attached to thevehicle chassis 90 by inserting thepin 88 into thebore 75 of thegrommet 70. Theridges 86 of thegrommet 70 are disposed against the mounting bracket or thevehicle chassis 90. More specifically, the HCU may be slipped onto the pin 90 (or pins 90) associated with each of thelow pressure accumulators 14 of the HCU that is provided with an associatedgrommet 70 to limit movement in two axes. The HCU is prevented from slipping back off of the pin(s) 88 (the third axis of movement) by the use of one or more conventional bolt/nut and grommet arrangement. The use of thelow pressure accumulator 14 and its associatedgrommet 70 as a mounting point thereby reduces the number of mounting bolts and associated rubber grommets, nuts and washers required to mount the HCU to thevehicle chassis 90 and speeds the time required to mount the HCU. - The novel shape of the
grommet 70 also facilitates improved passage of air as thepiston 45 moves, and provides an improved environmental seal which prevents water and contaminates from entering theaccumulator 14. As thepiston 45 moves toward the closed end 40 of thebody 34, air is drawn into a cavity between theclosed end 76 of thegrommet 45 and the closed end 48 of thepiston 45. Specifically, air flows between thegrommet 70 and thechassis 90, through thegrooves 84, through theaxial grooves 82 and through thepassageway 78. Conversely, as thepiston 45 moves away from the closed end 40 of thebody 34 and toward theclosed end 76 of thegrommet 45, air flows back through thenarrow slit 78, through theaxial grooves 82 and though thegrooves 84. Note that thepin 88 has a length shorter than the length of thebore 75 of thegrommet 70 and shorter than the length of theaxial grooves 82, such that air may flow through thegrooves 82 from the V-shapedgrooves 84 to theslit 78. - As indicated above, the novel shape of the
grommet 70 provides an improved environmental seal by providing a circuitous path for water and contaminates to flow. Further, thenarrow slit 78 is normally closed. Any water or contaminate that may flow through the circuitous path formed by the V-shapedgrooves 84 and theaxial grooves 82 is prevented from flowing through the normally closednarrow slit 78, thus providing an improved environmental seal. - The plurality of
narrow ridges 86 provide a reduced contact surface between thegrommet 70 and thevehicle chassis 90. The crown-shaped geometry creates a “dual rate” effect that is more compliant for low amplitude vibration. That is, the reduced contact surface allows thegrommet 70 to efficiently absorb energy generated by high frequency, low amplitude vibration typically generated by the brake system 10 and prevents the transfer of the energy to thevehicle chassis 90. Additionally, the reduced contact surface allows thegrommet 70 to absorb the energy typically generated by the vibration of the vehicle during travel on a road surface and prevents the transfer of road vibration through thechassis 90 to the brake system 10. - The accumulator assembly of the present invention has been explained and illustrated in its preferred embodiment. However, it will be appreciated that various modifications may be made to the accumulator assembly without departing from the spirit of the present invention. For example, while the preferred embodiment of the invention utilizes
axial grooves 82 within thebore 75 of thegrommet 70 for the passage air, other means could be used. For example, grooves could be formed on an outer surface of the mountingpin 88. - The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
Claims (18)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/969,543 US6634386B1 (en) | 2001-10-02 | 2001-10-02 | Fluid accumulator for use in a vehicle anti-lock brake system |
DE10246030A DE10246030A1 (en) | 2001-10-02 | 2002-10-02 | Fluid store, for ABS braking system, has sealing buffer to provide venting path |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/969,543 US6634386B1 (en) | 2001-10-02 | 2001-10-02 | Fluid accumulator for use in a vehicle anti-lock brake system |
Publications (2)
Publication Number | Publication Date |
---|---|
US6634386B1 US6634386B1 (en) | 2003-10-21 |
US20030205283A1 true US20030205283A1 (en) | 2003-11-06 |
Family
ID=25515667
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/969,543 Expired - Fee Related US6634386B1 (en) | 2001-10-02 | 2001-10-02 | Fluid accumulator for use in a vehicle anti-lock brake system |
Country Status (2)
Country | Link |
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US (1) | US6634386B1 (en) |
DE (1) | DE10246030A1 (en) |
Cited By (4)
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US20100263368A1 (en) * | 2006-12-19 | 2010-10-21 | Bernhard Gnamm | Hydraulic unit of a hydraulic vehicle brake system |
JP2011213260A (en) * | 2010-03-31 | 2011-10-27 | Nissin Kogyo Co Ltd | Vehicle brake fluid pressure control device |
US20110277863A1 (en) * | 2010-05-13 | 2011-11-17 | Mando Corporation | Low pressure accumulator for anti-lock brake system |
US10422354B2 (en) * | 2017-03-28 | 2019-09-24 | Denso Corporation | Hydraulic accumulator and manufacturing method thereof |
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US8640314B2 (en) | 2010-08-03 | 2014-02-04 | Federal-Mogul Corporation | Piston assembly transportation and installation apparatus and methods of transporting and installing a piston assembly therewith |
US9080710B2 (en) * | 2011-01-21 | 2015-07-14 | Hamilton Sundstrand Corporation | Accumulator reservoir venting |
DE102011089951A1 (en) * | 2011-12-27 | 2013-06-27 | Robert Bosch Gmbh | Hydraulically controlled storage chamber valve |
EP3045762B1 (en) * | 2015-01-14 | 2019-03-13 | Volvo Car Corporation | Elastically deformable damper |
US10370177B2 (en) * | 2016-11-22 | 2019-08-06 | Summit Packaging Systems, Inc. | Dual component insert with uniform discharge orifice for fine mist spray |
DE102021128767A1 (en) | 2021-11-04 | 2023-05-04 | Zf Active Safety Gmbh | Hydraulic control unit and hydraulic vehicle brake system |
CN117381377B (en) * | 2023-10-30 | 2024-05-24 | 江苏奕隆机电科技有限公司 | ABS hydraulic regulator energy accumulator assembly line |
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US2780504A (en) | 1954-04-21 | 1957-02-05 | Parker Appliance Co | Accumulator piston |
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US3863677A (en) | 1973-04-23 | 1975-02-04 | Parker Hannifin Corp | Accumulator with combination guide and seal ring |
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US5363744A (en) | 1993-12-07 | 1994-11-15 | Federal-Mogul Corporation | Accumulator piston having multiple elastomeric seals |
US5673978A (en) * | 1993-12-07 | 1997-10-07 | Kelsey-Hayes Company | Pressure attenuators and networks for anti-lock braking systems |
US5531513A (en) | 1994-12-16 | 1996-07-02 | Kelsey-Hayes | High pressure accumulator/bypass valve with stationary high pressure seal |
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DE19721837A1 (en) * | 1997-05-24 | 1998-11-26 | Itt Mfg Enterprises Inc | Hydraulic vehicle brake system with wheel slip control and valve for such a brake system |
JPH10329699A (en) | 1997-06-03 | 1998-12-15 | Nisshinbo Ind Inc | Liquid pressure brake control device |
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US6145543A (en) | 1998-04-09 | 2000-11-14 | Unisia Jecs Corporation | Automotive hydraulic modulator |
US6254200B1 (en) * | 1998-10-30 | 2001-07-03 | Kelsey-Hayes Company | Supply valve for a hydraulic control unit of a vehicular braking system |
-
2001
- 2001-10-02 US US09/969,543 patent/US6634386B1/en not_active Expired - Fee Related
-
2002
- 2002-10-02 DE DE10246030A patent/DE10246030A1/en not_active Withdrawn
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100263368A1 (en) * | 2006-12-19 | 2010-10-21 | Bernhard Gnamm | Hydraulic unit of a hydraulic vehicle brake system |
US8359852B2 (en) | 2006-12-19 | 2013-01-29 | Robert Bosch Gmbh | Hydraulic unit of a hydraulic vehicle brake system |
JP2011213260A (en) * | 2010-03-31 | 2011-10-27 | Nissin Kogyo Co Ltd | Vehicle brake fluid pressure control device |
US20110277863A1 (en) * | 2010-05-13 | 2011-11-17 | Mando Corporation | Low pressure accumulator for anti-lock brake system |
US8474488B2 (en) * | 2010-05-13 | 2013-07-02 | Mando Corporation | Low pressure accumulator for anti-lock brake system |
US10422354B2 (en) * | 2017-03-28 | 2019-09-24 | Denso Corporation | Hydraulic accumulator and manufacturing method thereof |
Also Published As
Publication number | Publication date |
---|---|
DE10246030A1 (en) | 2003-04-24 |
US6634386B1 (en) | 2003-10-21 |
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