Disc brake system with ABS

• US 6,371,250 B1
• Filed: 06/11/2001
• Issued: 04/16/2002
• Est. Priority Date: 12/12/1996
• Status: Expired due to Term

• Current Assignee: BWI Company Limited SA (Shougang Corporation)
• Original Assignee: Delphi Technology, Inc. (Sapiens International Corp. NV)
• Inventors: Bunker, Kenneth J.
• Primary Examiner(s): Schwartz, Christopher P.
• Application Number:
  US09/878,548
• Publication Number:
  US 20020029939A1
• Time in Patent Office: 309 Days
• Field of Search: 188/18.A, 188/71.5, 188/72.4, 188/72.7, 188/73.38, 188/106.F, 188/141, 188/355, 188/358, 188/359, 303/2
• US Class Current: 188/18.00A
• CPC Class Codes: B60G 2200/142 with a single lateral arm, e.g. MacPherson type
• CPC Class Codes: B60G 2204/129 Damper mount on wheel suspension or knuckle
• CPC Class Codes: B60G 2206/50 Constructional features of wheel supports or knuckles, e.g. steering knuckles, spindle attachments
• CPC Class Codes: B60T 1/065 employing disc B60T1/062 takes precedence
• CPC Class Codes: B60T 8/345 having more than one brake circuit per wheel
• CPC Class Codes: B60T 8/368 combined with other mechanical components, e.g. pump units, master cylinders
• CPC Class Codes: B60T 8/4266 having an electro-mechanically actuated expansion unit, e.g. solenoid, electric motor, piezo stack
• CPC Class Codes: F16D 2055/0008 Brake supports
• CPC Class Codes: F16D 2055/0012 integral with vehicle suspension
• CPC Class Codes: F16D 2055/0062 Partly lined, i.e. braking surface extending over only a part of the disc circumference
• CPC Class Codes: F16D 2055/0091 Plural actuators arranged side by side on the same side of the rotor
• CPC Class Codes: F16D 2065/1316 radially segmented
• CPC Class Codes: F16D 2065/1348 resilient
• CPC Class Codes: F16D 2065/1368 with relative movement both radially and axially
• CPC Class Codes: F16D 2065/1384 to wheel hub
• CPC Class Codes: F16D 2065/1392 Connection elements
• CPC Class Codes: F16D 2065/1396 Ancillary resilient elements, e.g. anti-rattle or retraction springs
• CPC Class Codes: F16D 2121/20 using electromagnets
• CPC Class Codes: F16D 55/32 actuated by a fluid-pressure device arranged in or on the brake
• CPC Class Codes: F16D 55/36 Brakes with a plurality of rotating discs all lying side by side
• CPC Class Codes: F16D 55/40 : actuated by a fluid-pressure device arranged in or one the brake
• CPC Class Codes: F16D 65/0977 : Springs made from sheet metal
• CPC Class Codes: F16D 65/12 : Discs; Drums for disc brakes
• CPC Class Codes: F16D 65/123 : comprising an annular disc secured to a hub member; Discs characterised by means for mounting

Abstract

An ABS brake system employs two axially slidable brake discs and four brake pads that are biased to have floating light random contact therebetween in the off brake position. The ABS controller operates the brake pads with about one half of the usual brake pressure and about double the number of the usual braking and release cycles. The floating axially slidable brake discs and four brake pads have reduced residual torque drag during the brake release cycle and have reduced hystersis. The result is operation at a higher frequency and with less amplitude, than the usual sliding caliper and fixed brake system, and a resolution of a modulating scale for cycling that is usually associated with a much lower coefficient of friction surface than is actually present.

Claims

1. A vehicle wheel brake system for a wheel suspension assembly and having an anti-lock braking system (“

ABS”

) to provide a higher resolution brake apply and brake release relative to an ABS system having a single, fixed brake disc, the brake system comprising;

a mounting hub for a road wheel mounted on the wheel suspension assembly for rotation about a rotational axis;

at least two slidable brake discs mounted to slide axially along the hub between braking and off-brake positions;

a caliper including a fixed bridge and at least four (4) braking pads mounted on the fixed bridge to provide four braking surfaces for braking engagement with the opposing sides of each of the brake discs;

a pulse creator mounted on the hub for generating pulses;

a sensor mounted on the wheel suspension assembly for sensing pulses from the pulse creator and for providing signals with respect to the rotational condition of the road wheel;

an ABS controller connected to the sensor and providing signals when the wheel condition is within preset parameters relative to the speed of the vehicle to develop a theoretical deceleration curve for the stopping of the vehicle within a predetermined distance; and

a brake actuator system operable manually by the vehicle passenger and operable automatically by the ABS controller to operate the caliper to slide the brake discs axially and to cause application of the four brake pads at a pressure of about one-half or less of the pressure of operation of the fixed, brake disc system and a frequency of brake apply and release of at least double the frequency of brake apply and release of the fixed, brake disc system.

2. A vehicle wheel system in accordance with claim 1 wherein a hollow bore is formed in the suspension member to reduce the weight of the suspension member and to contain the force applicator at a location closer to a wheel-turning axis to allow a reduction in turning radius.

3. A vehicle wheel ABS braking system in accordance with claim 1, having reduced residual torque drag, comprising:

springs between the hub and inner portions of the slidable brake discs to mount the brake discs in a floating manner on the hubs; and

springs on the fixed caliper for holding the brake pads in position relative to the brake pads during vehicle wheel speed-up.

4. A vehicle wheel ABS braking system in accordance with claim 1 having reduced weight and reduced residual drag torque, comprising:

a hollow, cylindrical bore formed in the suspension member having a force actuator contained therein;

springs floating and supporting the slidable brake discs on the hub; and

springs on the caliper for engaging the slidable brake pads and for holding them in position relative to the slidable brake discs in the off-brake position to reduce residual torque drag therebetween.

5. A vehicle wheel braking system, in accordance with claim 1, wherein the brake actuator system comprises:

an integral, hydraulic cylinder for holding a hydraulic fluid integrally formed in a suspension member of the wheel suspension; and

a piston mounted in the integral hydraulic cylinder and is operable by the hydraulic system to engage the four brake pads with the two axially, slidable brake discs.

6. A vehicle wheel ABS braking system, in accordance with claim 1, wherein the brake pad actuator comprises a solenoid and an electrical system for selectively energizing and de-energizing the solenoid.

7. A vehicle wheel ABS braking system, in accordance with claim 1, wherein the brake actuator comprises:

a hydraulic system having a hydraulic cylinder at each wheel;

a hydraulic reservoir for containing hydraulic fluid at each of the ABS-controlled brake pads to supply hydraulic fluid to an adjacent, hydraulic cylinder; and

a pressure generator at each wheel suspension operable by the mass of the vehicle for pressuring the hydraulic fluid in each hydraulic reservoir.

8. A vehicle wheel ABS braking system, in accordance with claim 1, wherein the pulse generator comprises a ring of spaced generator elements mounted on a side of the rotatable hub;

and

the sensor comprises a magnetic sensor disposed on the suspension member closely adjacent the ring of spaced generator elements.

9. A vehicle wheel ABS braking system, in accordance with claim 1, wherein the caliper is mounted on the suspension member in a vertical plane through the rotational axis and above the rotational axis and a radially outer position relative to the rotational axis;

and

the pulse generator and the sensor are located radially inwardly of the caliper.

10. A vehicle disc brake and suspension system having an ABS system comprising:

a wheel suspension member having a hub and connections to other portions of the vehicle steering device;

at least two brake discs each having an inner portion slidably mounted on the hub for sliding in a direction parallel to the central axis of the hub between a braking position and off-brake position;

at least four braking pads including one outer, fixed, brake pad and at least three slidable brake pads each having a friction pad surface for applying braking torque to opposite sides of the brake disc when in the braking torque position to decelerate the engaged brake discs;

a hollow bore in the suspension member;

an actuator in the hollow bore of the suspension member for sliding the slidable brake pads and brake discs into the braking position;

force applicators for floating the brake discs to allow them to slide axially from a braking position to an off-braking position relative to the braking pads;

an outer rim portion on the braking disc rotating while in the off-brake position and engaging the slidable brake pad'"'"'s friction surface to slide the pad from the braking position to an off-brake pad position;

a caliper fixed to the suspension member and having slidable brake pads thereon operable by the actuator into braking engagement with the slidable brake discs;

a brake pad force applicator acting on the slidable brake pads, when its off-brake position, to constrain the friction pad surfaces engaging the brake disc to reduce tilting of the brake pads on the stationary support and its rubbing on the brake discs that would increase off-brake, residual torque; and

an ABS system for operating the brake pad force applicator within the hollow bore in the suspension member to slide the brake pads and brake discs iteratively to the braking position and releasing the brake pads and discs to slide to off-brake positions.

11. A vehicle ABS brake system, in accordance with claim 10, wherein the actuator for sliding the brake pads comprises a hydraulic cylinder and a piston in the cylinder for applying the brake pads at 40 BAR or less when the vehicle is on a high coefficient of friction road surface.

12. A vehicle ABS system, in accordance with claim 10, wherein the actuator for sliding the brake pads comprises a solenoid and an electrical system to operate the solenoid.

13. The vehicle ABS braking system, in accordance with claim 10, wherein the brake pad force applicator acts on the slidable brake pads, when the system is in an off-brake position to constrain the friction pad surfaces from engaging the brake discs and to reduce tilting of the brake pads and rubbing on the brake discs that increases off-brake, residual torque.

14. A disc brake system, in accordance with claim 13, wherein the brake pad force applicator applies force to each slidable brake pad to hold its face in a plane substantially parallel to the plane in which the disc is rotating to minimize tilting of the brake pad into engagement with the brake discs, which would cause disc thickness variation.

15. A disc brake system, in accordance with claim 14, wherein the brake pad force applicator comprises at least one spring pushing on the brake pads in a direction substantially normal to the rotational axis of the brake discs and normal to the path of travel of the brake pads along a stationary support.

16. A disc brake system, in accordance with claim 10, wherein a stationary support comprises a bridge;

the slidable brake pad comprises a slidable pad carrier mounted for sliding on the bridge and carrying the frictional pad surface thereon; and

the brake pad force applicator is positioned over the brake pad carrier and forces the brake pad carrier downwardly against the bridge.

17. A vehicle wheel suspension system having an ABS braking system comprising:

a suspension member;

at least one brake disc mounted on the suspension member for rotation with a wheel of the vehicle,

brake pads mounted on the suspension member for movement to a brake application position to engage the at least one brake disc to decelerate the wheel and for movement to a brake release position to allow the wheel to accelerate during an ABS braking operation;

a localized hydraulic system at each of a plurality of wheels without connection to a master cylinder for shifting the brake pads to the brake application position and for allowing the brake pads to shift to the brake release position;

a hydraulic reservoir mounted on the suspension at each wheel for containing hydraulic fluid;

a pressure generator at each wheel suspension independent of a connection to a master cylinder for an associated hydraulic reservoir operable by the vehicle mass movement to increase pressure in the reservoir; and

an ABS control system including an electrically operated actuator at each wheel suspension for operating the localized hydraulic system at each wheel suspension to iteratively shift the brake pads into the brake application position with vehicle wheel acceleration with intervals therebetween of wheel acceleration to stop the vehicle.

18. A vehicle suspension and ABS braking system, in accordance with claim 17, wherein the at least one brake disc comprises a pair of brake discs slidable mounted on the hub;

and

wherein four brake pads are mounted on the suspension member to engage four faces of the pair of brake discs.

19. A vehicle suspension and ABS braking system, in accordance with claim 17, wherein the hydraulic system comprises:

an integral, hollow cylinder formed in a stub axle suspension member; and

a piston mounted in the integral, hollow cylinder.

20. A vehicle suspension and ABS braking system, in accordance with claim 17, wherein the ABS control system comprises an intelligent control located at each wheel for controlling that wheels iterative brake application and brake release.

21. A method of braking a vehicle wheel using an ABS system having an ABS hydraulic system and an ABS controller, and a wheel brake having a caliper and at least two of slidable brake discs axially slidable on a rotatable wheel supporting hub and having at least four brake pads engageable with the brake discs, the method comprising:

operating the caliper to a braking position using 40 BAR or less of hydraulic fluid pressure to slide the brake pads and the slidable brake discs to a braking position;

releasing the hydraulic fluid to allow the slidable brake discs to slide axially on the hub and to engage the slidable friction pads and to push them to their off-brake positions;

floating the brake discs and the brake pads on their respective supports in the off-brake position to reduce off-brake frictional drag and tilting of this brake pads against the brake discs;

sensing operation of a brake pedal by the operator generating an excessive braking force and sensing wheel speed and an approaching lock up of the road wheel using an ABS controller;

activating the ABS hydraulic system by the ABS controller to shift the slidable brake pads on the fixed caliper with hydraulic pressure at 40 BAR or less; and

shifting slidable brake pads and slidable brake discs on their floating supports rapidly to the braking position with changes in pressure from 40 BAR and at a predetermined frequency in accordance with a stored algorithm in the ABS system.

22. A method of braking, in accordance with claim 21, including a reduction of weight of the system by forming a hollow, cylinder actuator bore in the suspension.

23. A method of braking, in accordance with claim 21, including positioning the caliper at about a 12:

00 o'"'"'clock position and above the rotating hub.

24. A method, in accordance with claim 21, including operating the piston within an integral cylinder at the top of the suspension member.

25. A method, in accordance with claim 21, including operating the caliper by the ABS controller in the ABS mode at 40 BAR or less pressure on a high, co-efficient of friction road surface and at a substantially higher frequency than a system operating at about 70 BAR or more pressure on the same high coefficient of friction road surface.

26. A method, in accordance with claim 25, including the step of operating the brake pads to engage and release the brake discs within the range of 8-20 Hertz for a low, coefficient of friction road surface.