EP4448354A1 - Soupape de frein à pleine puissance avec décalage de la pression de frein - Google Patents

Soupape de frein à pleine puissance avec décalage de la pression de frein

Info

Publication number
EP4448354A1
EP4448354A1 EP22790059.4A EP22790059A EP4448354A1 EP 4448354 A1 EP4448354 A1 EP 4448354A1 EP 22790059 A EP22790059 A EP 22790059A EP 4448354 A1 EP4448354 A1 EP 4448354A1
Authority
EP
European Patent Office
Prior art keywords
control valve
valve assembly
primary
brake
wheel brakes
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.)
Pending
Application number
EP22790059.4A
Other languages
German (de)
English (en)
Inventor
Peter Backes
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 Off Highway Solutions Minnesota Inc
Original Assignee
Zf Off Highway Solutions Minnesota Inc
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 Zf Off Highway Solutions Minnesota Inc filed Critical Zf Off Highway Solutions Minnesota Inc
Publication of EP4448354A1 publication Critical patent/EP4448354A1/fr
Pending 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
    • B60T11/00—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant
    • B60T11/10—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant transmitting by fluid means, e.g. hydraulic
    • B60T11/16—Master control, e.g. master cylinders
    • B60T11/20—Tandem, side-by-side, or other multiple master cylinder units
    • B60T11/21—Tandem, side-by-side, or other multiple master cylinder units with two pedals operating on respective circuits, pressures therein being equalised when both pedals are operated together, e.g. for steering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D11/00—Steering non-deflectable wheels; Steering endless tracks or the like
    • B62D11/02—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides
    • B62D11/06—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides by means of a single main power source
    • B62D11/08—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides by means of a single main power source using brakes or clutches as main steering-effecting means
    • 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
    • B60T8/24—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 vehicle inclination or change of direction, e.g. negotiating bends
    • B60T8/246—Change of direction

Definitions

  • the present invention relates to a brake valve for braking a vehicle, for example an agricultural tractor, in lightly loaded conditions.
  • Agricultural tractors have traditionally included braking only on the rear axle, which for many years met relevant braking requirements.
  • agricultural tractors have increased in size and operated at higher speeds.
  • Regulatory requirements have also been updated in view of these changes with an objective of maintaining operational safety.
  • brake systems for modem tractors are typically designed with enough braking power to meet stopping requirements at the highest laden mass and at the tractor’s maximum rated speed.
  • An improved hydraulic brake system for an agricultural tractor responds to forward movement of a brake pedal by increasing brake fluid pressure at rear wheel brakes and, after a predetermined amount of pedal travel, increasing the brake fluid pressure at the front wheel brakes.
  • Brake fluid pressure at the front wheel brakes increases at a higher rate than at the rear wheel brakes to simultaneously achieve a maximum braking force at both front and rear axles in response to full depression of the brake pedal.
  • the hydraulic brake system comprises a dual, tandem system having left and right pressure modulating valves.
  • Each pressure modulating valve includes a primary brake valve and a secondary brake valve assembled in tandem within a cylinder housing.
  • the primary brake valve is linked by a push rod to a brake pedal, through a modulating spring, and the primary brake valve and the secondary' brake valve each include a movable spool.
  • a first return spring is disposed between the primary spool and the secondary spool, and a second return spring is disposed between the secondary spool and an end wall of the cylinder housing.
  • the second return spring provides a spring force, greater than the spring force for the first return spring, such that the secondary spool does not begin modulating pressure until a predetermined pressure on the rear wheel brakes has been met.
  • the hydraulic brake system provides offset braking at die front axle by a predetermined amount.
  • brake pressure at the front wheel brakes increases proportionally with additional pedal force to a point where brake fluid pressure at. the rear wheel brakes and front wheel brakes are at their respective maximum.
  • light braking uses only the rear wheel brakes, thereby providing a controlled deceleration under unloaded and lightly loaded conditions while maintaining maximum braking performance at higher speeds and while heavily laden.
  • the hydraulic brake system is described in connection with an agricultural tractor, the hydraulic brake system can be used in connection with other vehicles as desired.
  • Figure 1 is a schematic diagram of a hydraulic brake system in accordance with one embodiment.
  • Figure 2 is the schematic diagram of Figure 1 with the brake pedal partially deflected for braking at the rear axle only.
  • Figure 3 is the schematic diagram of Figure 1 with the brake pedal being further deflected for braking at the front and rear axles.
  • Figure 4 is a graph illustrating front and rear brake pressure as function of brake pedal rotation.
  • Figure 5 is a graph illustrating front and rear brake pressure as function of brake pedal rotation including a front axle offset.
  • a hydraulic brake system in accordance with one embodiment is illustrated and generally designated 10.
  • the hydraulic brake system 10 responds to a forward movement of a brake pedal 100 by increasing brake fluid pressure at the rear wheel brakes 102L, 102R and, after a predetermined amount of pedal travel, increasing the brake fluid pressure at the front wheel brakes 104L, 104R.
  • the hydraulic brake system 10 is described below in connection with an agricultural tractor, but can be used with other vehicles as desired.
  • the hydraulic brake system 10 includes a control valve assembly 12, a hydraulic supply 14, and a brake fluid reservoir 16.
  • the hydraulic supply maybe a single supply to the control valve 12 or a separate supply for front and rear brakes.
  • the control valve assembly 12 comprises a split-brake system having two pressure modulating valves: a left pressure modulating valve 20 and a right pressure modulating valve 22.
  • Each pressure modulating valve 20, 22 includes a primary brake valve 24 and a secondary brake valve 26.
  • the primary brake valve 24 is linked through a modulating spring 101 by a push rod 106 to the brake pedal 100.
  • the left pressure modulating valve 20 and the right pressure modulating valve 22 are identical, and for simplicity the left pressure modulating valve 20 will now be described.
  • the left pressure modulating valve 20 includes a primary brake valve 24 and a secondary brake valve 26 that are assembled in series within a common housing, with the secondary brake valve 26 being used to supply pressurized brake fluid to the front wheel brakes 104L, 104R only after a sufficient amount of travel of the brake pedal 100.
  • the primaty brake valve 24 is a five-port, three-position directional control valve
  • the secondary brake valve 26 is a three-port, three-position directional control valve
  • the primary brake valve 24 and the secondary brake valve 26 include a movable spool (not shown in the figures), in particular a primary' spool and a secondary spool, respectively.
  • the spool belonging to the primary brake valve 24 is linked through the modulating spring 101 to the push rod 106 and to the pedal 100.
  • a first return spring 28 is disposed between the primary spool and the secondary spool, and a second return spring 30 is disposed between the secondary spool and an end wall of the common housing.
  • the primary' brake valve 24 includes a neutral position, a modulating position, and a fill position.
  • the input side of the primary brake valve 24 includes three input ports.
  • the first input port is coupled to the output side of the secondary brake valve 26 of primaiy brake valve 22 on the right side of the valve 12, the second input port is coupled to the hydraulic supply 14, and the third input port is coupled to the brake fluid reservoir 16.
  • the output side of the primary brake valve 24 has two output ports.
  • the first output is linked by a conduit to a hydraulic resolver (or a select-high valve) 31.
  • the second output is linked by a conduit to rear wheel brake 102L.
  • the resolver 31 directs the high pressure from the left and right secondary brake valves to both front wheel brakes 104L, 104R of the tractor vehicle.
  • each secondary valve is directed to a front left brake port or a front right brake port.
  • the output of the secondary brake valve 26 is open from the output of the secondary brake valve 26 of valve 22 on the right side of valve 12 to the front wheel brakes 104L, 104R thro ugh the resolver 31, and the hydraulic supply 14 is open to a rear wheel brake 102L, and communication to tiie brake fluid reservoir 16 is blocked.
  • the secondary brake valve 26 likewise includes a fill position, a modulating position, and a neutral position.
  • the hydraulic supply 14 is open to the first input port of the right primary' brake valve 24, and communication to the brake fluid reservoir 16 is blocked.
  • the hydraulic supply 14 is open to the first input port of the left primary brake valve 24, and communication to the brake fluid reservoir 16 is blocked.
  • the hydraulic circuit shown in Figure 1 includes a diagonal split connection between the left and right pressure modulating valves 20, 22.
  • the secondary brake valve 26 is in the modulating position, all ports are blocked, and no brake fluid is allow'ed to flow.
  • the secondary brake valve 26 is in the neutral position, it’s output to the primary brake valve 24 on the right side of the valve 12 is connected to the brake fluid reservoir 16 and the hydraulic supply 14 is blocked.
  • each primary' pressure modulating valve 24 is linked by a conduit to the corresponding rear wheel brake of the tractor vehicle and via another conduit to the front brakes 104L and 104R through the resolver 31.
  • the primary brake valve 24 and the secondary brake valve 26 are assembled in tandem, with the primary brake valve 24 being used to supply hydraulic pressure to the front brakes only after a sufficient amount, of brake pressure has been sent to the corresponding rear brake 102L or 102R.
  • Each pressure modulating valve 20, 22 is coupled to first and hydraulic second supply lines 34. 36 that link the hydraulic supply 14 to the primary and secondary' brake valves 24, 26, respectively.
  • Return conduits 38, 40 link each of the first and second brake valves 24, 26 to the brake fluid reservoir 16.
  • each pressure modulating valve 20, 22 is at reservoir 16 pressure.
  • the primary' brake valve 24 and the secondary' brake valve 26 are in the position shown in Figure 1.
  • the primary spool contained within the primary brake valves 24 moves from the neutral position, shown in Figure 1, to the fill position, shown in Figure 2. That is, initial brake actuation forces the primary’ brake valves 24 to move to the position shown in Figure 2.
  • This brake pedal movement causes an increase in fluid pressure, transmitted to the rear wheel brakes 102L. 102R.
  • Releasing die force on the brake pedals 100 allows the fluid to flow back to the primary brake valves 24 in the position shown in Figure 1, and ultimately the reservoir 16.
  • continued brake pedals movement causes the secondary brake valves 26 to move from the neutral position to the fill position, shown in Figure 3, and the primary' brake valves 24 is able to increase hydraulic pressure at the front wheel brakes 104L, 104R.
  • the secondary brake valves 26 interrupts the connection between the hydraulic supply 14 and the front wheel brakes 104L, 104R until a predetermined minimum amount of rear brake pressure. Therefore, in a state where the brake pedals 100 are not depressed by a predetermined amount, die brake fluid pressure in the rear wheel brakes 102L, 102R increases while the brake fluid pressure in the front wheel brakes 104L, 104R is unchanged.
  • the reaction area of the spools for braking on the front brakes 104L and 104R may be different than the reaction area of the spools for braking on the rear brakes 102L and 102R. This allows the brake pressure on the front brakes 104L and 104R to rise at a different rate than on the rear brakes 102L and 102R so as to meet at a preset maximum simultaneously in response to the full application of the brake pedals 100.
  • FIG. 4 a graph depicting the front/rear brake pressure without an offset is illustrated.
  • Figure 5 depicts the embodiment of Figures 1-3, which provides offset braking at the front brakes by a predetermined amount,
  • the hydraulic pressure at the rear wheel brakes 102L and 102R increase linearly and the hydraulic pressure at the front wheel brakes 104L and 104R remain at zero.
  • the hydraulic pressure at the front wheel brakes increases linearly, but at a faster rate when compared to the rear wheel brakes. Consequently, maximum braking at the front and rear axles is simultaneously reached at 100% of pedal travel in the illustrated embodiment.
  • the amount of offset and the rate of pressure rise at the front brakes 104L and 104R may be different than illustrated in Figure 5 as needed to meet the specific braking requirements of the tractor.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Braking Elements And Transmission Devices (AREA)

Abstract

La présente invention concerne un système de frein hydraulique amélioré pour un tracteur agricole. Le système de frein hydraulique répond au mouvement vers l'avant d'une pédale de frein par une augmentation de la pression de liquide de frein au niveau des freins de roue arrière et, après une quantité prédéterminée de déplacement de pédale, une augmentation de la pression de liquide de frein au niveau des freins de roue avant. La pression de liquide de frein au niveau des freins de roue avant augmente à une vitesse supérieure à celle au niveau des freins de roue arrière pour obtenir simultanément une force de freinage maximale au niveau des essieux avant et arrière en réponse à un enfoncement total de la pédale de frein.
EP22790059.4A 2021-12-17 2022-09-30 Soupape de frein à pleine puissance avec décalage de la pression de frein Pending EP4448354A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US202163290865P 2021-12-17 2021-12-17
PCT/IB2022/059360 WO2023111705A1 (fr) 2021-12-17 2022-09-30 Soupape de frein à pleine puissance avec décalage de la pression de frein

Publications (1)

Publication Number Publication Date
EP4448354A1 true EP4448354A1 (fr) 2024-10-23

Family

ID=83693033

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22790059.4A Pending EP4448354A1 (fr) 2021-12-17 2022-09-30 Soupape de frein à pleine puissance avec décalage de la pression de frein

Country Status (2)

Country Link
EP (1) EP4448354A1 (fr)
WO (1) WO2023111705A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025151401A2 (fr) * 2024-01-08 2025-07-17 CMBF Products, Inc. Système de soupape de frein hydraulique

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3863991A (en) * 1973-09-17 1975-02-04 Case Co J I Vehicle brake system
JPS56135357A (en) * 1980-03-27 1981-10-22 Komatsu Ltd Brake system for construction vehicle
WO2008001208A2 (fr) * 2006-06-28 2008-01-03 Studio Tecnico 6M S.R.L. Appareil d'actionnement
GB201720471D0 (en) * 2017-12-08 2018-01-24 Agco Int Gmbh Utility vehicle braking
US20210155215A1 (en) * 2018-04-04 2021-05-27 ZF Active Safety US Inc. Vehicle brake system with secondary brake module
IT201800007831A1 (it) * 2018-08-03 2020-02-03 Cnh Ind Italia Spa Valvola di potenza per freni
IT202000012430A1 (it) * 2020-05-26 2021-11-26 Cnh Ind Italia Spa Disposizione idraulica migliorata di controllo di un servofreno per veicoli da lavoro

Also Published As

Publication number Publication date
WO2023111705A1 (fr) 2023-06-22

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