GB2393160A

GB2393160A - Hydraulic system for anti roll bars for vehicles

Info

Publication number: GB2393160A
Application number: GB0317749A
Authority: GB
Inventors: Ivo Agner; Ing Thomas Nied-Menninger
Original assignee: LuK Fahrzeug Hydraulik GmbH and Co KG
Current assignee: LuK Fahrzeug Hydraulik GmbH and Co KG
Priority date: 2002-07-31
Filing date: 2003-07-29
Publication date: 2004-03-24
Anticipated expiration: 2023-07-29
Also published as: GB2393160B; DE10334705A1; FR2845317B1; GB0317749D0; FR2845317A1

Abstract

Device for actively stabilising the rolling motion of a vehicle which as an axle with two wheels. The vehicle has a transverse stabiliser which comprises two stabiliser sections which can be rotated relative to each other by swing motors 14,15. The motors are controlled through an electronic control unit, or can be biased by a hydraulic cylinder. A pump 1 supplies the hydraulic pressure, and a valve 4,6,7 interacts with the cylinder and controls the rotational direction and coupling of the stabiliser sections and/or the biasing of the stabiliser.

Description

amp - 1 23931 60

HYDRAULIC CHASSIS SYSTEM

The invention relates to a device for actively stabilizing the rolling motion of a vehicle, with at 5 least one axle having at least two wheels and provided with a transverse stabilizer which comprises two stabilizer sections which can be rotated relative to each other by a hydraulic device, such as for example swing motor, controlled through an electronic control 10 unit, or which can be tensioned through the hydraulic device, such as for example cylinder, with at least one pump supplying the hydraulic device, with a valve device which interacts with the hydraulic device and controls the rotational direction and coupling of the 15 stabilizer sections or the tensioning of the stabilizer. Devices of this kind are known. They have the drawback that the valve devices which are used are complicated 20 in their construction and have several magnetic valves with cost-intensive electro-magnets and involve a considerable circuitry expense for the change-over and safety valves.

25 It is the object of the invention to provide a device for active rolling motion stabilization which does not have these drawbacks and which has a simplified hydraulic switch plan.

30 This is achieved through a device for actively

- 2 - stabilising the rolling motion of a vehicle, with at least one axle having at least two wheels and provided with a transverse stabiliser which comprises two stabilizer sections which can be rotated relative to 5 each other by a hydraulic device, such as for example swing motor, controlled through an electronic control unit, or which can be tensioned through the hydraulic device, such as for example cylinder, with at least one pump supplying the hydraulic device, with a valve 10 device which interacts with the hydraulic device and controls the rotational direction and coupling of the stabilizer sections or the tensioning of the stabilizer whereby the valve device has a change-over valve and a direction valve which hydraulically follows the change 15 over valve. A device is preferred in which the direction valve is changed over through the pressures in the pressure regions which are associated with the swing motor or cylinder of the front axle.

20 A device according to the invention is characterized in that the change-over valve regulates and controls the pressures for the swing motor or cylinder of the front axle (right/left) and the direction valve controls the pressures for the swing motor or cylinder of the rear 25 axle. Furthermore a device is preferred in which a fail-safe function is possible independent of the other functions through a separate fail-safe valve and two non-return valves.

30 A device is also preferred in which a plausibility

À 3 control is possible by comparing the electrical current signals of the change-over valve and pressure signals.

The invention will be described with reference to an 5 embodiment shown in the drawings in which: Figure 1 shows the actual state of a standard system; 10 Figure 2 shows an alternative concept according to the invention; Table 1 considers the faults of the actual state; Table 2 considers the faults of the alternative concept; and Table 3 shows important features of the 20 alternative concept.

Figure 1 shows the actual state of a standard system.

The pressure supply unit is a suction-throttled radial piston pump 21 with an adjustable suction throttle 20 25 which sets up two different pressure levels through a cascade circuit by means of two proportional pressure restricting valves 22 and 28 which are switched in as differential pressure valves. The pressure levels are monitored by pressure sensors 23 and 27. These pressure 30 regions are each marked by 35 for the right side and 34

- 4 - for the left side for a swing motor on the stabilizer on the front axle, and correspondingly by 33 and 32 for a swing motor on the stabilizer on the rear axle. The pressure on the rear axle must always be lower than the 5 pressure on the front axle. When driving round bends these two pressure levels are changed over to the right or left by means of a 7/2-way valve 24 depending on direction so that each time in synchronization either the pressure in the swing motors on the right or on the 10 left side of the vehicle is increased or lowered.

Additionally a fail-safe valve 25 is provided on the front axle which in the fail-safe scenario during jamming of a valve or power failure serves to block the swing motor 37 of the front axle and to switch the 15 swing motor 36 of the rear axle pressure-less.

Additionally there are two anti-cavitation valves 29 and 30 provided which each can connect the connector 35 and 34 of the swing motor 37 on the front axle to the tank pipe and the tank 31 so that a throttled free 20 rocking of the swing motor 37 can take place through the leakage point in the swing motor itself through sucking back the volume flow without cavitation problems. 25 The aim of the alternative concept is to simplify the hydraulic plan. The alternative concept likewise has a suctionthrottled pump 1 with a regulable suction throttle 16 and a cascade switching of the pressure restricting valve, in this case valves 4 and 5. Valve 30 5 can be comparable with the valve 28 of Figure 1. The

- 5 valve 4 has functional superiority on the one hand as pressure restricting valve and on the other as change-

over valve for changing the direction from right to left and vice versa. This valve 4 is operated by means 5 of two electrically controllable setting devices, for example proportional magnets. The valve functions in the manner of a "Wheatstone bridge", i.e. with an open central position whereby each time a control edge is active only in a right or left switched position which 10 adjusts the pressure either on the right side 10 of the swing motor 14 on the front axle or on the left side 11. A combination is hereby provided between direction reversal and pressure restriction. Furthermore a fail-

safe valve 6 is also shown which can be used in the 15 event of a power failure to block the swing motor 14 of the front axle whilst the pressure of the swing motor 15 of the rear axle can be regulated by means of the pressure restricting valve 5 and/or where necessary an anti-cavitation valve 18. The direction reversal at 20 the rear axle takes place through a direction valve 7 which hydraulically follows the pressures in the connections 10 and 11 of the swing motor 14 on the front axle and in direct proportion loads the associated connections 13 (dependent on 10) or 12 25 (dependent on 11) with pressure. It can happen that the direction valve 7 as a result of a faulty function or through dirt jams and thereby a false position is set, i.e. that the valve piston thus does not follow as it should. A unsafe chassis state is thereby prevented 30 by non-return valves 8 and 9 arranged between the

- 6 relevant pressure areas 10, 13 and 11, 12 which in each case prevent the pressure on the associated side of the rear axle from being greater than the pressure on the associated side of the front axle.

In a driving situation for example pressure prevails on the left side in the swing motor 14 of the front axle, whilst on the right side in the swing motor 14 of the front axle the pressure is equal to nil. If the valve 10 7 is not to follow through a fault, then if pressure prevails on the left part of the front axle, the pressure would also initially be on the right part of the rear axle. The fault is however corrected by the non-return valves 8 or 9, as described below.

If pressure prevails at the connection 10 and no pressure at the connection 11 then it is desired that pressure prevails also prevails at the connection 13 and no pressure at the connection 12. If by mistake 20 pressure does prevail at the connection 12 and no pressure were at the connection 11 then the pressure at the connection 12 breaks down in the direction of the connection 11 through the non-return valve 8. There is thus no unsafe chassis state since in this case the 25 rear axle becomes pressureless, and only the swing motor 14 on the front axle is biased with pressure corresponding to the curved direction.

At the same time with this alternative concept the 30 anti-cavitation valves 29 and 30 of Figure 1 can be

- 7 - spared because through the corresponding switching of the hydraulic plan the non-return valves 8 and 9 can also undertake this function direct since a connection of the swing motor 14 on the front axle directly to the 5 tank 17 in the anti-cavitation direction arises independently of the position of the direction valve 7, and on the other side a direct connection to the tank always exists through the valve 4. Thus the anti-

cavitation valves are spared and there is a double 10 function of the nonreturn valves 8 and 9 from pressure relief at the rear axle and anticavitation at the front axle.

The second advantage of this alternative concept is 15 that by using the valve 4 and by the safety coupling of the valve 7 with the non-return valves 8 and 9 the switch position recognition sensor 26 (Figure 1) of the direction valve 24 is spared, since a plausibility control can be carried out by means of the pressure 20 sensors 2 and 3 between the switch flows of the valve 4 - two electric magnets are provided here, one for the right side and one for the left side - and between the pressures for the right and left side. If the magnetic flow occurs on the right side and the pressure on the 25 right side does not follow correspondingly, then a faulty function of the valve 4 or valve 5 can exist in some way. A simple plausibility control is possible, and through the arrangement of two electric setting devices (electro-magnets) on the valve 4 a direct 30 direction recognition is possible without additional

- 8 - sensors with a current supply of the electric valve.

If the pressure on the corresponding side does not follow, then a faulty function exists, and a fail safe warning and corresponding safety functions can be 5 triggered whilst a faulty function of the valve 24 in Figure 1 cannot be detected through the pressures, since it is not in practice possible to associate the current of the operating magnet of the 7/2 way valve 24 with the pressures.

With the actual state of the standard system with the hydraulic switch plan (Figure 1) the switch recognition sensor 26 is required in order to establish whether the slider of the direction valve 24 follows the electrical 15 signal of the setting device of the valve 24, since it is not possible to make a plausibility check of the above kind. The pressures at the valves 22 and 28 can be changed electrically in any way and these pressure differences can also be measured but these pressure 20 differences have no influence on the position in which the 7/2 way valve 24 stands. Seen purely hydraulically this only defines the slider itself, and therefore the path sensor 26 is needed in order to accurately detect whether the right or left side of the swing motors 36 25 and 37 is loaded with pressure.

In the alternative concept (Figure 2) according to the invention with the valve 4 the pressure must be increased if the slider is operated on one side by 30 means of the electrically controllable setting device.

- 9 If this pressure is not increased then the slider jams either in the middle position or in the opposite position. If the pressure is increased the direction change-over functions in the correct manner, and the 5 pressure follows the current signal into the other direction and vice versa. Thus it is possible through a simple plausibility check to recognize whether the slider 4, with which the direction change-over is also integrated in addition to pressure regulation, 10 functions correctly, namely through the plausibility check between current signal and following pressure signal, and therefore it is possible to omit the switch position recognition sensor 26 (Figure 1).

15 The alternative concept according to the invention thus has the following advantages: a) it is possible to omit the switch position recognition sensor since a plausibility check is 20 possible between the electrical current signals of the magnets and pressure signals; b) the relatively complicated 7/2 way valve 24 of Figure 1 can be simplified by dividing this direction function to two valves whereby the second valve 7 25 follows hydraulically the first valve 4.

In order to guard against a breakdown of the hydraulic sequence of the valve 4 it is possible to mount two non-return valves 8 and 9 in the hydraulic circuit 30 which however represent no additional structural

- 10 elements compared to Figure 1 because these also undertake identically the anti-cavitation function of the front axle swing motor 14. Thus the switch position recognition sensor 26 is spared and the complicated 5 valve 24 omitted The patent claims filed with the application are proposed wordings without prejudice for obtaining wider patent protection. The applicant reserves the right to 10 claim further combinations of features disclosed up until now only in the description and/or drawings.

References made in the sub-claims refer to the further design of the subject of the main claim through the 15 features of the relevant subclaim; they are not to be regarded as dispensing with obtaining an independent subject protection for the combination of features of the subclaims referred to.

20 Since the subjects of the sub-claims can form independent inventions compared with the prior art

known on the priority date the applicant reserves the right to make them the subject of independent claims or part declarations. They can also contain independent 25 inventions which have a configuration independent of the subjects of the preceding sub-claims.

The embodiments are not to be regarded as restricting the invention. Rather numerous modifications and 30 amendments can be made within the scope of the present

- 11 disclosure, more particularly those variations,

elements and combinations and/or material which for example through combination or modification of individual features, elements or method steps contained 5 in the drawings and described in connection with the general description and embodiments as well as claims,

can be derived by the expert to solve the problem set and which through combinable features lead to a new subject or new method steps or sequence of method 10 steps, insofar as they relate to manufacturing, test and work methods.

Claims

1. Device for actively stabilizing the rolling motion of a vehicle, with at least one axle having at least 5 two wheels and provided with a transverse stabilizer which comprises two stabiliser sections which can be rotated relative to each other by a hydraulic device, such as for example swing motor, controlled through an electronic control unit, or which can be tensioned LO through the hydraulic device, such as for example cylinder, with at least one pump supplying the hydraulic device, with a valve device which interacts with the hydraulic device and controls the rotational direction and coupling of the stabilizer sections or 15 the tensioning of the stabilizer, characterized in that the valve device has a change-over valve and a direction valve which hydraulically follows the change-

over valve.

2. Device more particularly according to claim 1, characterized in that the direction valve is changed-

over through the pressures in the pressure areas and which are associated with the swing motor or the 25 cylinder of the front axle.

3. Device, more particularly according to claim 1 or 2, characterized in that the change-over valve 30 regulates and reverses (right/left) the pressures for

- 13 the swing motor or cylinder of the front axle and the direction valve reverses the pressures for the swing motor or cylinder of the rear axle.

s

4. Device more particularly according to one of the preceding claims characterized in that a fail-safe function independent of the other functions is made possible through a separate fail-safe valve and two 10 non-return valves.

5. Device more particularly according to one of the preceding claims characterized in that a plausibility 15 control is possible by comparing the electrical current signals of the change-over valve and pressure signals.

6. Device for actively stabilising the rolling motion 20 of a vehicle, with at least one axle having at least two wheels and provided with a transverse stabilizer which comprises two stabilizer sections rotatable relative to each other by means of a hydraulic device, such as swing motor, controlled by an electronic 25 control unit or which can be tensioned through the hydraulic device, such as for example cylinder, with at least one pump supplying the hydraulic device, with a valve device which interacts with the hydraulic device and controls the rotational direction and coupling of 30 the stabiliser sections, characterized by at least one

- 14 inventive feature disclosed in the application documents. 5

7. Device for actively stabilizing the rolling motion of a vehicle substantially as herein described with reference to Figure 2 of the accompanying drawings.