WO2020021297A1 - Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire - Google Patents

Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire Download PDF

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Publication number
WO2020021297A1
WO2020021297A1 PCT/IB2018/000762 IB2018000762W WO2020021297A1 WO 2020021297 A1 WO2020021297 A1 WO 2020021297A1 IB 2018000762 W IB2018000762 W IB 2018000762W WO 2020021297 A1 WO2020021297 A1 WO 2020021297A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
fluid
brake actuator
pressure chamber
actuator
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.)
Ceased
Application number
PCT/IB2018/000762
Other languages
English (en)
Inventor
Senthil Kumar ARANGARASAN
Subramanian MURUGAN
Nandakumar SUBRAMANIAN
Selvamani Sundaramahalingam
Malaiappan Viswanathan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF Commercial Vehicle Control Systems India Ltd
Original Assignee
Wabco India Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Wabco India Ltd filed Critical Wabco India Ltd
Priority to PCT/IB2018/000762 priority Critical patent/WO2020021297A1/fr
Publication of WO2020021297A1 publication Critical patent/WO2020021297A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/08—Brake cylinders other than ultimate actuators
    • B60T17/081—Single service brake actuators
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/02—Fluid pressure
    • F16D2121/04—Fluid pressure acting on a piston-type actuator, e.g. for liquid pressure
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/06—Pistons
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/08—Seals, e.g. piston seals
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/12—Membrane or diaphragm types

Definitions

  • Brake actuator for a vehicle in particular commercial vehicle
  • the invention relates to a brake actuator for a vehicle, in particular commercial vehicle, the brake actuator comprising an actuator housing having a piston chamber and a first fluid opening for providing pressurized fluid to the piston chamber from a pressure source, a push rod mounted inside the housing, the push rod having a mounting interface for coupling the push rod to a brake mechanism and being configured for reciprocating movement between a retained position and an extended position, and a piston that is coupled to the push rod.
  • Brake actuators of the aforementioned type are widely used in the vehicle industry to provide braking force for brake mechanisms. Under commercial vehicle, in particular busses, cargo vehicles such as trucks and other heavy duty vehicles are to be understood.
  • the aforementioned brake actuators operate as a function of pressurized fluid being provided from a pressure source to the brake actuator. By pressurizing the piston chamber with pressurized fluid, the piston is moved from its retained position towards an extended position in which braking force is transmitted via the push rod to an externally coupled brake mechanism such as a brake caliper of a disk brake or a drum brake, for instance.
  • Conventional brake actuators and in particular service brake actuators comprise a diaphragm which is sealingly mounted to the actuator housing and together with corresponding walls of the housing defines a pressure chamber.
  • the first fluid opening opens into said pressure chamber and the pressurized fluid entering the pressure chamber is effective to deform the diaphragm, thereby expanding the volume of the pressure chamber.
  • the diaphragm is then pushed against the adjacently mounted piston and push rod, which leads to the movement of the push rod and transmission of the braking force.
  • the diaphragm does not always form a constant contact surface with the adjacent piston along the entire travel path of the piston/push rod when being deformed by
  • the invention consequently suggests a brake actuator according to claim 1.
  • the invention in particular suggests a brake actuator of the initially mentioned type wherein the piston sealingly abuts against the actuator housing and divides the piston chamber into a pressure chamber and a non-pressure chamber, the first fluid opening being in fluid communication with the pressure chamber such that pressurized fluid entering the pressure chamber through the first fluid opening acts directly on the piston.
  • the inventive brake actuator preferably is a service brake actuator.
  • the invention is based upon the realization that by removing the diaphragm from the service portion of a conventional brake actuator, the issue of leakage of pressurized fluid out of the actuator housing can reliably be prevented.
  • the sealing function can be as reliably performed by an internal sealing in between the piston and the actuator housing.
  • the contact surface between the pressurized fluid and the piston is constant such that linear force transmission as a function of the input pressure is reliably provided.
  • the piston comprises a sealing element abutting sealingly against the actuator housing, and a separate sliding bearing, the sliding bearing having at least one bearing element protruding radially from the piston and contacting the actuator housing.
  • the bearing element preferably is a single bearing ring.
  • the at .least one bearing element may however also be formed as a plurality of bearing elements distributed over the circumference of the piston.
  • the at least one bearing element has a convex surface that is elastically deformed when in contact with the actuator housing.
  • the convex surface of the bearing element ensures a low contact surface, depending on the amount of elastic deformation. At the same time, the contact surface is still reliably provided when the piston is slightly tilted sideways with respect to its normal sliding direction between the retained position and the extended position.
  • the sealing element projects radially outwards from the piston such that the piston can pivot with respect to the actuator housing.
  • the piston is thus configured as a rocking piston which significantly improves the articulation of the piston while at the same time reducing the risk of mechanical damage to the piston or the actuator housing.
  • the brake actuator comprises a second fluid opening that is in fluid communication with the non-pressure chamber.
  • the second fluid opening is preferably configured for providing fluid to the non pressure chamber when the piston is moved towards the retained position.
  • the second fluid opening is preferably configured to allow venting of the non-pressure chamber when moving the piston towards the extended position in order to prevent build-up of unwanted residual positive pressure inside the non-pressure chamber.
  • the brake actuator preferentially comprises a manifold valve that is in fluid communication with the first fluid opening, the second fluid opening, and a pressure source, and configured to supply pressurized fluid from the pressure source to the first fluid opening when the pressure source is engaged, and redirect pressurized fluid from the first fluid opening to the second fluid opening when the pressure source is released.
  • “engaged” means that pressurized fluid is being provided from the pressure source towards the manifold valve
  • “released” is understood to mean that no pressurized fluid is being provided from the pressurized source towards the first fluid opening, in particular because of the operation of the manifold valve.
  • the benefit of having the manifold redirect pressurized fluid from the first fluid opening to the second fluid opening is that positive fluid pressure can be maintained inside also the non-pressure chamber of the brake actuator housing.
  • the redirection usually takes place when the operator of a vehicle does not provide a braking signal or has ended providing a braking signal, e.g. by taking the foot off the brake pedal.
  • the pressure source is released, and the pressurized fluid in the pressure chamber can escape through the first fluid opening towards the second fluid opening which allows the piston to return from its extended position towards the retained position.
  • the brake actuator comprises a quick return valve that is associated with the second fluid opening.
  • the quick return valve is configured to close and open, i.e. establish, fluid communication with the associated non-pressure chamber.
  • the brake actuator comprises a third fluid opening that is in fluid communication with the non-pressure chamber, and an exhaust check valve associated with the third fluid opening, wherein the exhaust check valve is operable between a closed state and an open state. In the closed state, the exhaust check valve prevents fluid passage through the third fluid opening, while in the open state, fluid can pass by the exhaust check valve in the direction of the pressure radiant.
  • the exhaust valve is configured such that pressurized fluid can exit the non-pressure chamber but cannot enter the non-pressure chamber.
  • the exhaust check valve has a. valve element that is biased with a pre-load towards the closed state such that the pre-load must be overcome in order to move the valve element from the closed state towards the open state.
  • the bias towards the closed position ensures that the pressure inside the non pressure chamber is always slightly above ambient pressure, as a certain predefined pressure must be applied to the valve element from within the non pressure chamber in order to overcome the pre-load.
  • the valve element may comprise or consist of an elastically deformable membrane or flap, for example.
  • the brake actuator comprises a return spring that is mounted inside the actuator housing, in particular inside the non pressure chamber, and is effective to move the piston towards its retained position.
  • the brake actuator comprises a seal bushing that is mounted to the actuator housing on the side of the non-pressure chamber, wherein the seal bushing sealingly and slidably supports the push rod.
  • the seal bushing comprises a gaiter extending outwards of the actuator housing in the direction of the push rod, covering and sealingly abutting against the push rod.
  • the gaiter is preferably effective to seal the actuator housing against entry of fluid and debris.
  • the seal bushing preferably consists at least in part of a thermoplastic polymer, preferably a polyacetal polymer, preferably an acetal homopolymer. Polyacetal is also referred to as
  • POM poiyoxymethylene
  • FIG. 1 a schematic cross-sectional view of a brake actuator according to a preferred embodiment.
  • the accompanying figure shows a brake actuator 1 according to a preferred embodiment of the invention.
  • the brake actuator 1 is a service brake actuator and thus consists of a service portion 2.
  • the inventive actuator 1 would comprise a service portion in addition to other functional portions such as a spring portion for emergency and park brake functions.
  • the brake actuator 1 comprises an actuator housing 3.
  • the actuator housing 3 is closed by a housing cover 5.
  • a piston 7 is mounted inside the actuator housing 3 and configured to reciprocatingly move between a retained position (shown in the figure) and an extended position. In order to reach the extended position, the piston 7 is moved along axis X to the right in the orientation according to the figure.
  • the piston 7 is coupled to a push rod 9 configured to transfer the movement of the piston 7 to an externally coupled braking mechanism.
  • a return spring 11 is positioned inside the actuator housing 3 and effective to push the piston 7 and push rod 8 towards the retained position.
  • the actuator housing 3 contains a piston chamber which is divided by the piston 7 into a pressure chamber 15 and a non-pressure chamber 17. In order to do so, the piston 7 abuts sealingly with a sealing element 21 against a chamber wall 23 of the actuator housing 13.
  • the piston 7 is guided by a sliding bearing 19 having an annular bearing element that is convexly shaped and in contact with the chamber wall 23 of the actuator housing.
  • the sliding bearing 19 is elastically deformed when in contact with the chamber wall 23.
  • the piston 7 is slidably held by a seal bushing 25 that is mounted to the housing cover 5 of the brake actuator 1.
  • the seal bushing 25 is coupled with a gaiter 27 that extends externally to the actuator housing 3 protects the actuator 1 from e g. water or debris.
  • the push rod 9 comprises in one end portion a connection interface 28 which is coupled with the piston 7, preferably by a thread connection. On the opposite end portion, the push rod 9 comprises an external connection interface 29 for coupling the push rod 9 to a brake mechanism.
  • the actuator housing 3 For operation of the brake actuator 1, the actuator housing 3 comprises a first fluid opening 31 which is in fluid communication with the pressure chamber 15 and connectable to a pressure source 100 of a vehicle.
  • the brake actuator 1 further comprises a second fluid opening 33 that is laterally provided on the actuator housing 3.
  • the brake actuator 1 comprises a manifold valve 32 that is configured to either fluidly connect the pressure source 100 to the first fluid opening 31 , or, in a second switching state, fluidly connect the first fluid inlet 31 to the second fluid inlet 33.
  • a quick return valve 34 is associated with the second fluid inlet 33 and operative to open and close the fluid communication with the associated non-pressure chamber 17.
  • the brake actuator 1 further comprises a third fluid opening 35 and an exhaust check valve 36 associated with the third fluid opening 35 and effective to allow venting of the non-pressure chamber 17.
  • the exhaust check valve 36 preferably comprises an elastically deformable valve element 37 in the shape of a flap.
  • the valve element 37 is elastically deformable and biased towards the closed position which is shown in the figure.
  • the bias produces a pre-load that has to be overcome by positive pressure inside the non-pressure chamber 17. Hereby, inadvertent buildup of negative pressure inside the non-pressure chamber 17 is prevented.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Abstract

L'invention concerne un actionneur de frein (1) destiné à un véhicule, en particulier un véhicule utilitaire, l'actionneur de frein comprenant un boîtier d'actionneur (3) comprenant une chambre de piston (15, 17) et une première ouverture de fluide (31) pour fournir un fluide sous pression à la chambre de piston à partir d'une source de pression (100), une tige de poussée (9) montée à l'intérieur du boîtier d'actionneur (3), la tige de poussée (9) comportant une interface de montage (29) pour accoupler la tige de poussée (9) à un mécanisme de frein et étant conçue pour un mouvement de va-et-vient entre une position retenue et une position étendue, et un piston (7) qui est accouplé à la tige de poussée (9). En particulier, l'invention suggère que le piston (7) vienne en butée de manière étanche contre le boîtier d'actionneur (3) et divise la chambre de piston en une chambre de pression (15) et une chambre de non-pression (17), la première ouverture de fluide (31) étant en communication fluidique avec la chambre de pression (15) de telle sorte que le fluide sous pression entrant dans la chambre de pression (15) à travers la première ouverture de fluide (31) agisse directement sur le piston (7).
PCT/IB2018/000762 2018-07-23 2018-07-23 Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire Ceased WO2020021297A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IB2018/000762 WO2020021297A1 (fr) 2018-07-23 2018-07-23 Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2018/000762 WO2020021297A1 (fr) 2018-07-23 2018-07-23 Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire

Publications (1)

Publication Number Publication Date
WO2020021297A1 true WO2020021297A1 (fr) 2020-01-30

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PCT/IB2018/000762 Ceased WO2020021297A1 (fr) 2018-07-23 2018-07-23 Actionneur de frein destiné à un véhicule, en particulier un véhicule utilitaire

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1249530A (en) * 1968-12-09 1971-10-13 Certain Teed Prod Corp Internal air assisted brake actuator
DE2411438A1 (de) * 1974-03-09 1975-09-11 Knorr Bremse Gmbh Bremszylinder
DE3935663A1 (de) * 1989-10-26 1991-05-02 Bosch Gmbh Robert Federspeicherzylinder, insbesondere fuer druckluftbremsanlagen fuer kraftfahrzeuge
WO2009103431A2 (fr) * 2008-02-22 2009-08-27 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Cylindre de frein pour des freins actionnés par air comprimé de véhicules
WO2010040509A1 (fr) * 2008-10-09 2010-04-15 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Cylindre de frein de véhicule comprenant un système d'étanchéité tolérant des inclinaisons d'un piston de frein rigide
EP2353953A1 (fr) * 2010-01-28 2011-08-10 KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH Cylindre de freinage d'accumulateur à ressort doté d'un joint formant une section transversale d'écoulement s'élargissant

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1249530A (en) * 1968-12-09 1971-10-13 Certain Teed Prod Corp Internal air assisted brake actuator
DE2411438A1 (de) * 1974-03-09 1975-09-11 Knorr Bremse Gmbh Bremszylinder
DE3935663A1 (de) * 1989-10-26 1991-05-02 Bosch Gmbh Robert Federspeicherzylinder, insbesondere fuer druckluftbremsanlagen fuer kraftfahrzeuge
WO2009103431A2 (fr) * 2008-02-22 2009-08-27 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Cylindre de frein pour des freins actionnés par air comprimé de véhicules
WO2010040509A1 (fr) * 2008-10-09 2010-04-15 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Cylindre de frein de véhicule comprenant un système d'étanchéité tolérant des inclinaisons d'un piston de frein rigide
EP2353953A1 (fr) * 2010-01-28 2011-08-10 KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH Cylindre de freinage d'accumulateur à ressort doté d'un joint formant une section transversale d'écoulement s'élargissant

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