GB2337730A

GB2337730A - An active vehicle anti-roll apparatus

Info

Publication number: GB2337730A
Application number: GB9807087A
Authority: GB
Inventors: Roderick Mcintyr Harvey-Bailey
Original assignee: HARVEY BAILEY ENGINEERING LIMI
Current assignee: HARVEY BAILEY ENGINEERING LIMI
Priority date: 1998-04-03
Filing date: 1998-04-03
Publication date: 1999-12-01
Anticipated expiration: 2018-04-03
Also published as: GB2337730B; GB9807087D0

Abstract

Respective double acting rams (24,26) are connected between each wheel (12, 14) of a transverse pair of wheels and the vehicle body (10). The wheels (12,14) are also connected to the body (10) by conventional suspension apparatus, such as wishbones (16, 18), springs (20) and dampers (22). Each ram (24, 26) has an upper chamber (24A, 26A) and a lower chamber (24B, 26B) and respective conduits (28, 30) connect the upper chamber of each ram with the lower chamber of the transversely opposite one. A central processing unit (CPU) receives at least one signal indicative of parameters, such as vehicle weight, lateral acceleration, steering wheel angle, tending to induce vehicle roll, and this CPU transmits signals to a control valve (36) through which fluid may be supplied from a pump and fluid reservoir (not shown) to pressurise either one of the conduits (28,30) or neither of them. When pressure is applied, a clockwise or anti-clockwise anti-roll movement, respectively, is exerted upon the wheels (12, 14).

Description

- 1 2337730 IMPROVEMENTS IN OR RELATING TO A VEHICLE ANTI-ROLL APPARATUS

The present invention relates to an active anti-roll apparatus for a vehicle.

In particular the invention relates to an anti-roll apparatus arranged to be fitted to a vehicle already provided with a conventional suspension apparatus.

The intended function of an anti-roll apparatus according to the present invention is, to correct the vehicle body roll which is induced as a vehicle negotiates corners and the apparatus according to the present invention is not intended for the correction of pitch or the adjustment of vehicle height.

The present invention seeks to provide an vehicle anti-roll apparatus in which an anti-roll moment can be applied to either or both of the front and rear pairs of wheels.

Accordingly, the present invention provides an active anti-roll apparatus for a vehicle, the vehicle including first and second transverse pairs of ground contacting wheels and a suspension apparatus disposed between the sprung and the unsprung mass of the vehicle, the anti-roll apparatus comprising a double-acting ram connected between each wheel of at least one pair of transverse wheels and the vehicle sprung mass, each ram including upper and lower chambers, the rams associated with the said pair of transverse wheels being interconnected by conduits which connect the upper chamber of one ram with the lower chamber of the transversely opposite ram and vice-a-versa, f luid pump means to pump fluid into said conduits via valve means and a control means receiving at least one input signal indicative of the forces tending to induce vehicle roll and having output signals to control the valve means.

The active anti-roll apparatus can be applied to both pairs of wheels.

The active anti-roll apparatus can include means to provide differential anti-roll moments between the two pairs of ground contacting wheels.

The rams can also act as dampers by the provision of restrictions and nonreturn valves.

The or each valve means can include three valve positions in which either no anti-roll moment is applied to either or both pairs of ground contacting wheels or an anti-roll moment in a clockwise or anti-clockwise direction is applied progressively to the or each pair of ground contacting wheels.

The present invention will now be more particularly described with reference to the accompanying drawings in which 1 7 Figure 1 shows a partial front view of a vehicle including one form of anti-roll apparatus according to the present invention and Figure 2 shows a diagrammatic representation of an anti-roll apparatus according to the present invention fitted to both the front and the rear pairs of wheels of a vehicle.

Referring to Figure 1, there is shown a vehicle body (10) having a pair of wheels (12, 14) which are attached to the vehicle by a conventional suspension apparatus comprising upper and lower wishbones (16, 18), springs (20) and dampers (22).

Double acting rams (24, 26) are attached between the vehicle body (10) and the wheels (12, 14) respectively.

The double acting rams have upper and lower chambers (24A, 26A and 24B, 26B) respectively and the rams have cylinder rods and pistons (24C, 26C and 24D, 26D) respectively.

The upper cylinder (24A) of ram (24) is connected by a conduit (28) to the lower chamber (26B) of the ram (26) whilst the upper chamber (26A) of the ram (26) is connected to the lower chamber (24B) of the ram (24) by a conduit (30).

A spring-loaded expansion chamber (32) is connected to the conduit (28) and spring-loaded expansion chamber (34) is connected to the conduit (30).

The conduits (28, 30) are of sufficiently large bore in order to permit unrestricted movement of f luid within the conduits and thereby not to restrict movement of the wheels (12, 14), when they are displaced with the vehicle in motion.

A pump (not shown) and a f luid reservoir (not shown) driven by the engine provides pressure through the valve (36) to the conduits (28, 30).

The valve (36) under the control of a central processor unit (CPU) (not shown) can progressively adopt one of three positions, a neutral position in which the conduits (28, 30) are not pressurised and hydraulic fluid can flow freely from the upper conduit of one ram to the lower conduit of the transversely opposite and vice-a-versa i.e. no anti-roll moment is applied, or one of two positions in which either a clockwise or an anticlockwise anti-roll moment is applied to the wheels (12, 14). In addition, restriction can be applied in the neutral position to provide a passive anti-roll moment, if desired.

Referring to Figure 2 which shows an anti-roll apparatus applied to both the front and rear pairs of wheels of a vehicle, the features common to the arrangement shown in Figure 1 have been given identical reference numerals.

Double acting rams (38, 40) are connected between each one of the rear pair of wheels (not shown) and the vehicle body (10) and the rams have upper and lower chambers, pistons and piston rods (38A, 40A and 38B, 40B and 38C, 40C and 38D, 40D) respectively.

The upper chamber (38A) of ram (38) is connected to the lower chamber (40B) of ram (40) by a conduit (42) whilst the lower chamber (38B) of ran (38) is connected to the upper chamber (40A) of ram (40) by a conduit (44) and each conduit (42, 44) is provided with a spring-loaded expansion chamber (46, 48) respectively.

A central processing unit (48) receives signals which are indicative of the forces tending to produce roll of the vehicle e.g. a lateral accelerometer signal (50), a signal (52) indicative of the vehicle weight, a signal (54) indicative of the position of the vehicle steering wheel, and a signal (not shown) indicative of vehicle speed.

The CPU (48) also receives signals (56, 58) via pressure transducers (60, 62) respectively which indicate the pressure in conduits (30, 28) together with signals (64, 66) which indicate the pressure in conduit (42, 44), via pressure transducers (70, 68).

A valve (72) equivalent to the valve (36) is provided to control the flow to the conduits (42, 44).

An engine-driven pump (not shown) applies hydraulic oil under pressure to a conduit (74) to the valves (36, 72).

- 6 Both valves (36, 72) have three positions indicated A, B and C on Figure 2.

As shown in Figure 2, the valves (36, 72) are both in position B which is the neutral position and no pressure is applied to any of the rams (24, 26, 38, 40) because the CPU (48) is not receiving any signal indicating the requirement for an anti-roll moment to be applied. Normally the valves (36, 72) are in the neutral position when the vehicle is travelling substantially in a straight line. In such a situation if any or all of the rams (24, 26, 38, 40) are displaced vertically, for example, due to discontinuities in the road surface, hydraulic fluid will simply be displaced from the lower chambers to the upper chambers of each transverse pair of rams and the displaced hydraulic fluid will be passed to the tank (not shown) by a conduit (76).

If the vehicle negotiates a left-hand curve the vehicle will tend to roll in a clockwise direction thereby requiring rams (24, 38) to descend and the rams (26, 40) to ascend. This means that a greater pressure has to be applied to the conduits (28, 44) as compared to the conduits (30, 42). The CPU calculates, depending on the input signals the total amount of anti-roll moment required to correct the vehicle roll, and can apportion that amount between the front and rear wheels as desired. Therefore, the CPU (48) operates the valves (36) so that the valves progressively move to position A until the required differential pressure between the conduits (28, 30 and 38, 40) are sensed by the transducers (60, 62 and 68, 70), to correct the roll.

i The CPU (48) continuously monitors the pressures in the conduits (28, 30 and 42, 44) and thereby continuously varies the position of the valves (36, 72) to maintain the desired pressure differential and therefore the desired anti-roll moment, continuously adjusting the anti-roll moment according to the input signals, particularly those indicative of lateral acceleration and steering wheel angle.

Conversely, if the vehicle negotiates a right-hand bend, then the pressure in the conduits (30, 44) must be greater than the pressure in the conduits (28, 42). According to the input signals to the CPU (48) the valves (36, 72) will be moved towards position C in order that an appropriate anti-roll moment is applied to the vehicle via the rams (24, 26 and 38, 40).

It will be appreciated that the amount of anti-roll moment applied under the control of the CPU (48) can be varied by appropriate programming of the CPU. Thus the CPU can selectively control the pressure differential between the conduits (28, 30 and 32, 44). This feature allows a different anti-roll moment to be applied to each set of vehicle wheels.

This feature can be important because depending upon the vehicle weight, type of suspension and weight distribution, it may be desirable to apply different anti-roll moments to each pair of vehicle wheels.

A further feature of the invention is the provision of damping - 8 valves (78, 80) to each of the four double acting rams. In this form the rams can replace the conventional dampers (22) which are shown in Figure 1.

The apparatus can be applied to a vehicle having any f orm of conventional suspension, e.g. wishbone, as illustrated, trailing arm and rigid axle.

Claims

An active anti-roll apparatus f or a vehicle, the vehicle including f irst and second transverse pairs of ground contacting wheels and a suspension apparatus disposed between the sprung and the unsprung mass of the vehicle, the anti-roll apparatus comprising a double acting ram connected between each wheel of at least one pair of transverse wheels and the vehicle sprung mass, each ram including upper and lower chambers, the rams associated with the said pair of transverse wheels being interconnected by conduits which connect the upper chamber of one ram with the lower chamber of the transversely opposite ram and vice-a-versa, f luid pump means to pump f luid into said conduits via valve means and a control means receiving at least one input signal indicative of the forces tending to induce vehicle roll and having output signals to control the valve means.

An active roll control apparatus as claimed in claim 1 in which the wheels of both pairs of wheels are provided with a double acting ram, the rams of each pair of transverse wheels being interconnected.

An active roll control apparatus as claimed in claim 1 or claim 2 in which the input signals are indicative of vehicle weight, lateral acceleration, steering wheel angle, 4 and vehicle speed.

4. An active roll control system as claimed in claim 1 or claim 2 or claim 3 in which the anti-roll moments applied to the said two pairs of wheels can be substantially the same, or one anti-roll moment can be greater than the other.

5. An active roll control apparatus as claimed in any one of the preceding claims in which the double acting rams include damping valves.

6. An active roll control apparatus constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.