GB2285778A

GB2285778A - Vehicle roll control system

Info

Publication number: GB2285778A
Application number: GB9400718A
Authority: GB
Inventors: Gary Chris Fulks
Original assignee: ACG France SAS
Current assignee: ACG France SAS
Priority date: 1994-01-15
Filing date: 1994-01-15
Publication date: 1995-07-26
Anticipated expiration: 2014-01-15
Also published as: DE19500869C2; GB9400718D0; DE19500869A1; GB2285778B

Description

2285;P7,9 VEHICLE ROLL CONTROL SYSTEM The present invention relates to a

roll control system for a motor vehicle.

The aim of the present invention is to provide a roll control system which is only active when one or more monitored vehicle conditions indicates roll control is required.

To this end, a vehicle roll control system in accordance with the present invention for a vehicle having a pair of wheels each rotatable on an axle, comprises a torsion bar; a first arm extending substantially perpendicular to the torsion bar, the first arm being fixed to the torsion bar at one end and being connectable to one of the axles at the other end; a second arm extending substantially perpendicular to the torsion bar, the second arm being rotatably mounted on the torsion bar at one end and being connectable to the other axle at the other end; and rotation control means connected between the second arm and the torsion bar, the rotation control means being actuable on detection of a predetermined vehicle condition to substantially prevent or allow rotation of the second arm relative to the torsion bar, the rotational control means comprising a braking surface fixed to the torsion bar adjacent said one end of the second arm, and a braking means mounted on the second arm and actuable to frictionally grip the braking surface to substantially prevent rotation of the second arm relative to the torsion bar.

The present invention will now be described by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a schematic presentation of a vehicle incorporating a first embodiment of vehicle roll control system in accordance with the present invention at the front and at the rear of the vehicle; 2 is Figure 2 is a side view of the vehicle roll control system at the front of the vehicle shown in Figure 1; Figure 3 is a side view of the first arm of the vehicle roll control system shown in Figure 2; Figure 4 is a side view of the second arm, hydraulic actuator (shown in cross-section) and lever arm of the vehicle roll control system shown in Figure 2; Figure 5 is a schematic diagram of part of the hydraulic and electrical control circuit of the vehicle roll control system shown in Figure 2; and Figures 6 and 7 are a similar views to Figures 4 and 2 respectively of a second embodiment of vehicle roll control system in accordance with the present invention.

Referring to Figure 1, a vehicle 10 is shown schematically and comprises a pair of front wheels 12 each rotatably mounted on an axle 14, a pair of rear wheels 16 each rotatably mounted on an axle 18, and a shocking absorbing system 20 associated with each wheel. A vehicle roll control system 22 in accordance with the present invention is associated with the front wheels 12, and a vehicle roll control system 24 in accordance with the present invention is associated with the rear wheels 16. The vehicle roll control systems 22, 24 are substantially the same but with modifications made solely to allow fitting to the vehicle 10.

Referring in more detail to Figures 2 to 5, the vehicle roll control system 22 for the front of the vehicle comprises a torsion bar 26, a first arm 28, a second arm 30, a brake surface defined by a rotor disc 32, and a braking means defined in part by a hydraulically actuable caliper 34. The torsion bar 26 is mounted on the vehicle by a pair of resilient mounts 3 is 36 in conventional manner to extend longitudinally between the wheels 12. The first arm 28 (Figure 3) is fixed at one end 38 by a splined connection 40 to the torsion bar 26. The other end 42 of the first arm 28 is connected to the axle 14 of one of the front wheels 12. The second arm 30 (Figure 4) is rotatably mounted at one end 44 on the torsion bar 26 by way of a bearing 46. The other end 48 of the second arm 30 is connected to the axle 14 of the other front wheel 12. The first and second arms 28, 30 extend substantially parallel to one another when the vehicle is stationary, and substantially perpendicular to the torsion bar 26.

The rotor disc 32 (Figure 4) is substantially annular and is fixed at its centre 50 to the torsion bar 26 by a splined connection 52 substantially adjacent the one end 44 of the second arm 30 and the bearing 46. The caliper 34 (Figure 2) is mounted on the second arm 30 and a bridge portion 54 thereof straddles a portion of the periphery 56 of the rotor disc 32. The caliper 34 further comprises a housing 58 which defines a fluid chamber 60 within which is mounted a piston 62 which makes a sealing sliding fit with the housing, and a leg 64. As shown in Figure 2, the housing 56 is connected to one end of the bridge portion 54, and the leg 64 is connected to other end 54 of the bridge portion. The caliper 34 is mounted on the second arm 30 in such a manner that the caliper can reciprocate a limited distance towards and away from the second arm. Brake pads 65,67 are attached to the leg 64 and to the piston 62 respectively such that a friction material lining on each brake pad is directed towards the braking surfaces on the rotor disc 32.

The fluid chamber 60 (see Figure 5) is fluidly connectable by a fluid line 66 to a fluid pressure source 82. A solenoid operated valve 68 may be positioned in the fluid line 66, the valve being biased 4 is to a normally closed position. A fluid reservoir 80 supplies hydraulic fluid to the fluid pressure source 82 by way of a fluid line 84. A one- way valve 86 is positioned in the fluid line 84 to prevent flow of fluid from the fluid pressure source 82 to the fluid reservoir 80. A pressure relief valve 88 may be positioned in a fluid line 90 connecting the fluid chamber 60 to the fluid reservoir to limit the pressure in the fluid chamber to a predetermined maximum. The presence of the solenoid valve 68, pressure relief valve 88 and fluid line 90 are optional, but allow the hydraulic circuit to be self-primed and bled.

The fluid pressure source 82 comprises a fluid chamber 92 connected to fluid lines 66 and 84. A piston 94 makes a sealing fit in the fluid chamber 92 and is reciprocatingly driven by a nut 96 which is threadingly engaged to a screw 98. The screw 98 is rotatably driven by meshing gears 100 connected to a DC electric motor 102. Actuation of the DC motor 102 drives the piston 94 to increase or decrease the fluid pressure in the fluid chamber 92.

The operation of the DC motor 102 and the solenoid valve 68 (when present) is controlled by an electronic and/or computerised control module 70 (Figure 5). The control module 70 operates the DC motor 102 and the solenoid valve 68 dependent on predetermined vehicle conditions which are determined by signals from a steering sensor 72 (which monitors the steering angle of the front wheels 12) and/or a lateral g sensor 74 (which monitors the sideways acceleration of the vehicle). The control module 70 may also take into account signals received from a rotary displacement sensor 76 (which monitors the angle of displacement between the torsion bar 26 and the second arm 30) and/or a vehicle speed sensor 78 and/or any other is relevant parameter to determine the required state of operation of the valve 68.

If the control module 70 detects that roll control is required, the control module sends a signal to the solenoid operated valve 68 to open the valve, and sends a signal to the DC motor 102 to actuate the motor to move the piston 94 to increase the fluid pressure in the fluid chamber 92. This action increases the fluid pressure in the fluid chamber Go to move the piston 62 relative to the housing 58 to push the friction lining on brake pad 67 against the rotor disc 32, and by reactive force, push the friction lining on the brake pad 65 against the rotor disc. Consequentially, the rotor disc 32 is frictionally gripped by the brake pads 65,67 to thereby substantially lock the second arm 30 relative to the torsion bar 26 and provide roll control for the vehicle 10.

If the control module 70 detects that roll control is no longer required, the control module sends a signal to the DC motor 102 to drive the piston 94 to reduce the fluid pressure in the fluid chamber 92, and then sends a signal to the solenoid operated valve 68 to close the valve. Fluid pressure in the fluid chamber 60 is reduced to release the grip of the brake pads 65,67 on the rotor disc 32, allowing the rotor disc to rotate relative to the caliper 34, thereby allowing rotation of the second arm 30 relative to the torsion bar 26.

As shown in Figure 2, a carrier tube 120 may be mounted on the torsion bar 26. The fluid pressure source 82 may be mounted on the carrier tube 120 along with associated components such as the fluid reservoir 80, solenoid operated valve 68, one-way valve 86, and pressure relief valve 88, with portions of the fluid lines 66,90 to the caliper 34, being flexible. This arrangement allows the vehicle roll control system 22 6 is to be assembled as a separate module (with the exception of the control module 70 and associated sensors 72-78) for subsequent attachment to the vehicle 10. The carrier tube 120 also provides protection for the torsion bar 26. The same control module 70 can be used for both front and rear vehicle roll control systems 22,24 and thereby provide associated roll control for the front and the rear of the vehicle 10.

The solenoid operated valve 68 may be biased to be normally open, but closable when actuated by the control module 70 on detection of the predetermined vehicle conditions. other forms of fluid pressure source may be used beside the arrangement described above. The caliper 34 may be replaced by one having a pair of pistons positioned on opposite sides of the rotor disc, each having a brake pad attached thereto and each movable by fluid pressure. In this case, the caliper may be fixedly mounted on the second arm 30. As a further alternative, the hydraulic circuit may be omitted, and the piston or pistons in the caliper may be actuated directly by a DC electric motor controlled by the control module 70.

In the second embodiment of a vehicle roll control system as shown in Figures 6 and 7, parts which correspond to those of the first embodiment described above have been given the same reference numeral. In this second embodiment, the braking surface is defined by a brake drum 122 which is substantially annular and which is attached at its centre 124 to the torsion bar 26 by splined connection 52. The braking means is defined by a brake cylinder 126 and a pair of brake shoes 128. The brake cylinder 126 has a bore 130 extending therethrough which defines a fluid chamber, and from which a piston (not shown) protrudes at each end. Each piston acts on one end of each brake shoe 128, and the other end of each brake shoe is pivotally 1 7 mounted on an extension 132 of the second arm 30. Each brake shoe 128 comprises a backing plate 134 with a friction lining material 136 attached thereto and directed towards the inner circumferential surface 138 of the brake drum 122. The rest of the hydraulic circuit is as shown in Figure 5, with the caliper 34 replaced by the brake cylinder 126. On detection of the need for roll control, the hydraulic circuit is actuated as described above to increase the fluid pressure in the fluid chamber in the brake cylinder 126. This pressure increase causes the pistons in the brake cylinder 126 to move outwardly to push the friction lining 136 on the brake shoes 128 into engagement with the inner surface 138 of the brake drum 122. Consequentially, the brake drum 122 is frictionally gripped by the brake shoes 128 to thereby substantially lock the second arm 30 relative to the torsion bar 26 and provide roll control for the vehicle 10.

In a modification of this second embodiment, the hydraulic circuit may be omitted, and the pistons in the brake cylinder may be actuated directly by a DC electric motor 8 is

Claims

Claims: -

1. A vehicle roll control system for a vehicle having a pair of wheels each rotatable on an axle, comprising a torsion bar; a first arm extending substantially perpendicular to the torsion bar, the first arm being fixed to the torsion bar at one end and being connectable to one of the axles at the other end; a second arm extending substantially perpendicular to the torsion bar, the second arm being rotatably mounted on the torsion bar at one end and being connectable to the other axle at the other end; and rotation control means connected between the second arm and the torsion bar, the rotation control means being actuable on detection of a predetermined vehicle condition to substantially prevent or allow rotation of the second arm relative to the torsion bar, the rotation control means comprising a braking surface fixed to the torsion bar adjacent said one end of the second arm, and a braking means mounted on the second arm and actuable to frictionally grip the braking surface to substantially prevent rotation of the second arm relative to the torsion bar.

2. A vehicle roll control system as claimed in Claim 1, wherein the braking surface is defined by a rotor disc, and the braking means comprises a caliper which straddle a portion of the periphery of the rotor disc and a pair of brake pads mounted on the caliper and frictionally engageable with opposed sides of the rotor disc on movement of one or more pistons slidably mounted in the caliper.

3. A vehicle roll control system as claimed in Claim 1, wherein the braking surface is defined by a brake drum, and the braking means comprises a brake cylinder positioned inside the brake drum and a pair of brake shoes frictionally engageable with the brake drum J 9 is on movement of one or more pistons slidably mounted in the brake cylinder.

4. A vehicle roll control system as claimed in Claim 2 or Claim 3, wherein the piston or pistons are moved by hydraulic fluid pressure.

5. A vehicle roll control system as claimed in Claim 2 or Claim 3, wherein the piston or pistons are moved by a DC electric motor.

6. A vehicle roll control system substantially as hereinbefore described with reference to, and a shown in, Figures 1 to 5 of the accompanying drawings.

7. A vehicle roll control system substantially as hereinbefore described with reference to, and a shown in, Figures 1, 3 and 5 to 7 of the accompanying drawings.