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
  • 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
  • B60T8/17—Using electrical or electronic regulation means to control braking
  • B60T8/1701—Braking or traction control means specially adapted for particular types of vehicles
  • B60T8/1708—Braking or traction control means specially adapted for particular types of vehicles for lorries or tractor-trailer combinations
• • 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
  • B60T8/17—Using electrical or electronic regulation means to control braking
  • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
  • B60T8/1764—Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear

Definitions

• This invention relates to an anti-lock braking system and an axle control valve for a vehicle with self-steerable wheels, especially but not exclusively a trailer vehicle with compressed air braking.
• the invention is also applicable to a vehicle with force-steered wheels.
• wheels of a the vehicle of a steerable axle may be provided with means whereby when the vehicle is passing along a curved roadway, pivotal movement of the wheels of the steerable axle out of parallel with other wheels improves lateral stability and reduces tyre scrub.
• Such steerable wheels may be on a rigid axle or suspended independently.
• self-steerable wheels are provided with independent anti-lock control of their brakes the self-steer action, especially when being governed by wheel reaction forces with the roadway, can itself result in tyre wear and vehicle instability whilst an anti-lock mode is operating, due to differential braking forces and reactions at opposite wheels of the self-steerable axle.
• European Patent No. 0754609 proposes an anti-skid compressed air braking system for a trailer vehicle with a common brake pressure modulator valve which responds to respective wheel speed sensors at opposite sides of an allotted braked axle having anti-lock control via separate modulators, the common modulator providing the same brake pressure to both wheels of the self-steerable axle.
• the present invention seeks to provide an alternative system to the foregoing and having an axle control valve not requiring such a common modulator.
• an anti-lock braking system for a wheeled vehicle having a first axle with speed sensors for braked wheels thereof on opposite sides of the vehicle and an electronic control unit (ECU) which controls fluid pressure modulators to selectively control the respective brake pressures applied to brakes of said wheels in the event of incipient skidding being sensed, the system including means for directly applying output fluid braking pressure from either or both said modulators to brakes of wheels of a further steerable axle of the vehicle and control means whereby at onset of an anti-lock mode accompanied by differential pressures from said modulators the higher of the braking pressures is isolated from the brakes of the steerable axle.
• ECU electronice control unit
• control means is provided by an axle control valve with means to receive the respective output pressures of the brake pressure modulators and communicate them to a delivery port the axle control valve including respective solenoid valves controllable by signals from an anti-lock ECU to isolate the higher said output pressure from the delivery port.
• Fig 1 illustrates in schematic form interconnected components of a compressed air braking system of wheels of a trailer vehicle having three axles, one of which is a self-steered axle;
• Fig 2 illustrates diagramatically the example of an axle control valve for the braking system of Fig 1;
• Fig 3 illustrates, in graphical manner, operation of the axle control valve assembly of Fig 2
• the compressed air braking system of a two line trailer with electronic braking and anti-lock includes control and supply line couplers 1 and 2 respectively and a relay emergency valve 3 (of known form but which may be optional with EBS) via which a compressed air reservoir 4 is charged from a tractor system (not shown).
• the trailer has first, second and third axles with respective pairs of compressed air operable wheel brake actuators 12L, 12R and 13L, 13R and 14L, 14R.
• the third axle is self-steerable.
• Compressed air pressure graduable according to trailer control line pressure from the reservoir 4 is relayed via valve 3, a load control valve 5 (which again may not be a requirement with EBS) and respective left and right hand anti- lock pressure modulators 6L and 6R to the respective left and right hand brake actuators 12, 13.
• the actuators 14L and 14R are brake actuators of the steerable axle wheels which self-steer according to the reaction between the tyres thereof and the rolling surface to improve stability and minimise tyre wear.
• 14L and 14R are normally supplied with substantially equal brake pressure via an axle control valve 15.
• Valve 15 is supplied directly with pressures from both modulators 6L and 6R. In the present example these modulator pressures are controlled by an electronic ABS control unit (ECU) 16.
• ECU electronic ABS control unit
• axle control valve 15 operates to isolate from actuators 14R and 14L the highest modulator output. These actuators can therefore apply only equal and reduced brake forces, to both wheels of the steered axle corresponding to brake pressure at the lowest adhesion side of the first axle.
• the axle control valve 15 includes valve arrangements with respective two-state solenoid valves 20L and 20R which are identical and are each shown in an unenergised state wherein the areas above the diaphragms of respective open/closed diaphragm valves 23L and 23R are vented, trailer reservoir pressure at a port 21 being prevented from influencing respective diaphragm valves 23L and 23R.
• equal pressures at ports 22L and 22R and interconnection 24 from the ABS modulators for the middle axle are normally permitted to reach common output connections 25L and 25R to the brake actuators 13L and 13R of the self-steered axle.
• solid curves (a) and (b) respectively represent curves of wheel speed against time for right and left hand wheels of the first and second axles (the non — steering axles of the trailer.
• the broken curve (c) represents brake pressure to the right and the left hand wheel brake actuators of the third axle (the steerable axle) of the trailer and wheel speed is represented by the solid line curve (d) .
• an electronic control signal (e) is applied by the ECU to solenoid valve 20R to close the diaphragm valve 23R to pressure from modulator 6R.
• the pressure applied directly from only modulator 6L is thereby permitted to be the sole controlling pressure of the actuators 14R and 14L of the wheels of the steerable axle over a period DEF (curve c).
• Corresponding wheel speeds for the wheels of the steerable axle under braking are indicated diagramatically in curve (d) assuming identity of performance (which may not be so) between the steered wheels but those are simply exemplary.
• the actuators may be provided with actuator pressure through a common delivery port and via a common quick release valve.
• a common quick release valve may be integrated with an axle control valve unit according to the invention if so required.
• axle control valve Whilst the axle control valve described in the foregoing with reference to Fig 2 and Fig 3 of the accompanying drawings is described more especially in relation to anti-lock control of brakes of self-steerable axle during anti-lock braking of a vehicle, such an axle control valve may be employed in force-steerable axle arrangements. Moreover, such an axle control valve may be provided to afford simplified anti-lock control of brake pressure of wheels of a lifting axle the tyres of wheels of which contact the rolling surface only when the vehicle is heavy-laden. By such means the size of actuators to one or more other axles may be less than otherwise required, whilst providing extended distribution of braking of the vehicle.

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• Engineering & Computer Science (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Regulating Braking Force (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Cites Families (8)

• 2002
  • 2002-02-02 GB GB0202481A patent/GB2384838B/en not_active Expired - Fee Related
• 2003
  • 2003-02-03 AU AU2003244449A patent/AU2003244449A1/en not_active Abandoned
  • 2003-02-03 EP EP03737351A patent/EP1509433A1/de not_active Withdrawn
  • 2003-02-03 WO PCT/GB2003/000426 patent/WO2003066401A1/en not_active Ceased

Non-Patent Citations (1)

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