GB2057989A

GB2057989A - Anti-deflection device for an articulated vehicle

Info

Publication number: GB2057989A
Application number: GB8028193A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1979-09-01
Filing date: 1980-09-01
Publication date: 1981-04-08
Also published as: GB2057989B; SE445325B; FR2464173A1; SE8005717L; DE2935437C2; DE2935437A1

Abstract

The anti-deflection device comprises a separately-operable cylinder piston assembly (3l, 3r) arranged on each side of the central longitudinal axis of the vehicle. A steering-angle transducer (16) allows flow of pressure medium between the cylinders (3l, 3r) via restricting means (12l, 12r) for damping deflecting movement between the leading part and trailing part of the vehicle. A maximum-angle transducer (14) prevents flow of pressure fluid between the cylinders (3l, 3r) above a predetermined deflection angle ( beta ) thus hindering a further increase in the deflection- angle between the vehicle parts. <IMAGE>

Description

SPECIFICATION Anti-deflection device for an articulated vehicle This invention relates to an anti-deflection device for articulated vehicles, e.g. articulated motor buses, especially rear-drive buses, semitrailers or trailer-hauling motor trucks so as to damp swinging movements between the articulated parts and limit the deflection angle, i.e.

the angle of inclination between the longitudinal axes of the articulated parts.

An object of the invention is to provide such a device for preventing a certain deflection angle, as determined by.the steering angle, between the leading vehicle and the trailing vehicle from being exceeded especially when the roadway is smooth, and to maintain skidding and pendulum movements of the trailing vehicle within tolerable limits for all conditions of travel.

The invention provides an anti-deflection device for an articulated vehicle having a leading and trailing part, the device comprising a separately-operable cylinder-piston assembly arranged on each side of the central longitudinal axis of the vehicle, a steeringangle transducer allowing flow of pressure medium between the cylinders via restricting means for damping deflecting movement between the vehicle parts, and a maximumangle transducer preventing flow of pressure fluid between the cylinders above a pre-determined deflection angle thus hindering a further increase in the deflection angle between the vehicle parts.

Two embodiments of the invention are now described with reference to the accompanying drawings, in which: Figure 1 is a plan view of an articulated motor bus fitted with the device of the present invention, Figure 2 is a schematic view of a first embodiment of the device of the present invention plus electric circuitry, and Figure 3 is similar to the embodiment of Fig. 2 but with additional comparison means.

In Fig. 1, telescopically-extending hydraulic cylinders 31 and 3r with respective pistons are mounted between a leading part 1 and a trailing part 2 on either side of an articulated joint 4 of a vehicle. The cylinders 31 and 3r extend horizontally, and in straight-ahead travel of the vehicle, they are parallel to the direction of travel. The cylinders 31, 3r are single acting and are connected separately via respective pipes 8,, 8r to a shut-off valve 9, from where they are connected to each other via pipes 8,', 8rl, respectively, each of which incorporates a restrictor 12,, 1 2r, which may be adjustable.In parallel with this arrangement the pipes 8,', 8rl are connected to each other via a pipe 1 7 incorporating an automatic changeover valve 1 0. The pipe 1 7 is connected via a further pipe 18, a second shut-off valve 11, and a pipe 18', to a pipe 8" interconnecting the two restrictors 1 2. A hydraulic header 1 3 is also connected to the pipe 8". The pipes 8 8', 8r' are also connected to pipes 8,, 8r by check or non-return valves 19" 19, 19, respectively.

The two shut-off valves 9, 11 are controlled by solenoids, the first shut-off valve 9 being closed when its solenoid is electrically actuated an the second shut-off valve being open for passage when its solenoid is electrically actuated.

A steering-angle transducer 1 6 has one current input and a respective output for a left-hand and a right-hand steering angle a.

The transducer 1 6 is arranged such that its outputs will not be energized until the steering angles have reached an appreciable magnitude of, say, over 5 . A deflection-angle tranducer 1 5 and a maximum deflection-angle transducer 14 likewise each have one current input and a respective output for left-hand and right-hand steering angles, respectively.

Each output of the steering-angle transducer 1 6 is connected to the actuating solenoid of the second shut-off valve 11 and to the actuating solenoids of respective switches 5 and 5r, which when electrically actuated close to allow passage of current. Each output of the deflection-angle transducer 1 5 is connected to the actuating solenoids of respective switches 6 and 6" which when electrically actuated close to allow passage of current.The respective oppositely-directed switches, i.e. switches 5 and 6r on the one hand and switches 5 and 6 on the other hand, are connected in series, and their common output is connected to the actuating solenoid of the first shut-off valve 9 via a switch 8, which opens when the vehicle is put in reverse gear.

The two outputs of the maximum deflec tion-angle transducer 14 & are connected jointly also to the actuating solenoid of the first shutoff valve 9.

In Fig. 3 the outputs of the steering-angle transducer 1 6 and of the deflection-angle transducer 1 5 are connected separately to an electrical comparison means 7 the output of which is connected, together with the common output of the maximum deflection-angle transducer 14 and the output of the reversegear lock switch 8, to the actuating solenoid of the first shut-off valve 9.

The device of the present invention operates as follows: When travel is straight ahead or the steering angle is under, say, 5 , the steering-angle transducer 1 6 is open, and in the absence of actuating current the second shut-off valve 11 is closed. Since the actuating solenoids of the switches 5 and 5, are not actuated, these switches are open. The deflection-angle transducer 1 5 is open, so that also the actuating solenoids of the switches 61 and 6r are not actuated, so the switches are open.

It will have no bearing, then, that the shut-off switch 8 is closed for passage because of forward travel. The maximum deflection-angie transducer 14 is open, too, so that no actuating current flows to the actuating solenoid of the first shut-off valve 9, so that the valve will be open.

Sideways swinging movements of the trailing part are damped by pumping hydraulic medium from one to the other of the hydraulic cylinders 3" 3, through the first shut-off valve 9, which is open, and the pipes 8j, 8, incorporating the restrictors 12, and through the check valves 19" 19,. The changeover valve 10 has no effect, passage being prevented by the second shut-off valve 11.

In curves, when the steering angle exceeds 5 , the steering-angle transducer 16 is closed, and electrical current flows to the actuating solenoid of the second shut-off valve 11 through the right-hand or the left-hand output, thus opening the second shut-off valve 11.

Hydraulic medium, therefore, can flow from one cylinder to the other through the first shut-off valve 9, which is still open, through one portion of the changeover valve 10, through the second shut-off valve 11 and through only one restrictor 12, with the hydraulic header 13 always being connected.

This flow of hydraulic medium will not be prevented until the maximum deflection-angle transducer 14, on reaching the maximum allowable deflection-angle ssmax to the left or right-hand side, energises the actuating solenoid of the first shut-off valve 9, which will then disconnect the connecting pipes of the two hydraulic cylinders 3j, 3, from each other, immobilizing the cylinders and causing them to resist any additional increase in deflectionangle.

When skidding or jack-knifing is imminent, i.e., when the deflection-angle ss is in a direction opposite to the steering angle a, both groups of switches 5,, 6, and 5rz 6 are closed for passage because an output of the steeringangle transducer 1 6 opposite the deflectionangle transducer 1 5 is current energized. Inasmuch as the lock switch 8 is closed for passage when the vehicle travels ahead, current will now flow to the actuating solenoid of the first shut-off valve 9, causing it to close.

This again cuts the connecting pipes of the two hydraulic cylinders from each other and prevents any further increase in deflectingangle.

It is not until the vehicle is in reverse gear that lock switch 8 will open and interrupt the flow of current to the actuating solenoid of the first shut-off valve 9, which then permits passage. This permits an increase in deflection-angle ss until the maximum deflectionangle transducer 14 comes into action to supply current as described above.

The comparison means 7 will also supply current to the actuating solenoid of the first shut-off valve 9 when the deflection-angle ss unduly deviates from the steering angle ar, causing the valve 9 to close and immobilize the cylinders as described above.

Claims

1. An anti-deflection device for an articulated vehicle having a leading and trailing part, the device comprising a separately-operable cylinder-piston assembly arranged on each side of the central longitudinal axis of the vehicle, a steering-angle transducer allowing flow of pressure medium between the cyliners via restricting means for damping deflecting movement between the vehicle parts, and a maximum-angle transducer preventing flow of pressure fluid between the cylinders above a pre-determined deflection angle thus hindering a further increase in the deflection-angle between the vehicle parts.

2. An anti-deflection device as claimed in claim 1, wherein a) the cylinders are connected to each other via respective first pipes, via a first shutoff valve and via respective second pipes each incorporating a restrictor, and in parallel therewith via a connecting pipe incorporating an automatic changeover valve, b) the changeover valve and a pressure fluid reservoir are connected to the connecting pipe of the two restrictors via a further pipe and a second shut-off valve, c) the first shut-off valve is controlled by the maximum deflection-angle transducer, and the second shut-off valve is controlled by the steering-angle transducer, and d) the respective second pipes are connected to the respective first pipes via check valves such that pressure fluid will pass through the check valves in no direction other than towards the cylinders.

3. An anti-deflection device as claimed in claim 2, wherein the first shut-off valve is also controlled by the steering-angle transducer together with a deflection-angle transducer, a lock being incorporated to cut off the first shut-off valve when the vehicle is in.reverse gear.

4. An anti-deflection device as claimed in claim 2 or 3, wherein the first shut-off valve is controlled by comparison means for the steering angle and the deflection-angle.

5. An anti-deflection device as claimed in any one of claims 2 to 4, wherein the cylinder and piston assemblies are convential, telescopically-extending hydraulic cylinder and piston assemblies.

6. An anti-deflection'device as claimed in any one of claims 2 to 5, wherein the reservoir is a header of automatically variable volume.

7. An anti-deflection device as claimed in any one of claims 2 to 6, wheren shut-off valves are electrically operable.

8. An anti-deflection device as claimed in claim 7, wherein the steering-angle transducer has one input and respective outputs for lefthand and right-hand steering angles, the olit- puts being energized only when the steering angle exceeds substantially 5 , and the deflection-angle transducer and the maximum deflection-angle transducer have one input and respective outputs for left-hand and righthand steering angles.

9. An anti-deflection device as claimed in claim 8, wherein each output of the steering angle transducer is connected to a respective first switch, and the respective oppositelydirected output of the deflection-angle transducer is connected to a respective second switch connected in series to the first switches, the output of the first and second switches being connected jointly to the first shut-off valve.

10. An anti-deflection device as claimed in claim 9 and claim 3, wherein the lock, which comes into action when the vehicle is put in reverse gear, comprises a switch arranged between the joint output of the two groups of switches and the first shut-off valve.

11. An anti-deflection device as claimed in any one of claims 7 to 10 and claim 4, wherein the common outputs of the steeringangle transducer and of the deflection-angle transducer are connected separately to the comparison means, the output of which is connected to the first shut-off valve.

1 2. An anti-deflection device substantially as herein described with reference to the accompanying drawings.

1 3. An articulated vehicle provided with an anti-deflection device as claimed in any one of the preceding claims.