Vehicle provided with a controllable rigid axle

Abstract: A vehicle has a rigid shaft 1 mounted in bearing means 2, which rigid shaft 1 has ends connected to length-adjustable reaction-force elements 4 for influencing the rotation position of the shaft 1 in dependence on a desired change in the direction of motion of the vehicle. A means 13 is provided for supplying a signal which is dependent on the speed of the vehicle. Said speed dependent signal is led to a processing device 11, which device 11 is connected to said elements 4 for only allowing said elements 4 to access a signal dependent on the desired change of direction if the speed of the vehicle is less than a certain adjustable value.

Description: The invention concerns a vehicle as outlined in the preamble of claim 1. Such a vehicle is commonly known. In particular, one is reminded of vehicles which are suited for the transport of heavy loads, such as sand, scrap, rubble, asphalt, garbage, etc. A vehicle as described in the first paragraph is known from EP-A-0126387. It is known that the forces which arise in the chassis and, in particular, those parts of the suspension of, in particular, a rigid rear axle can be particularly large when the known vehicle is loaded, especially when taking a bend. For this reason, the chassis is made from a material which is suited to withstanding these forces. The disadvantage of such constructions is that they are, to a certain extent, unnecessarily heavy. The purpose of the invention is to provide a vehicle for the transport of, in particular, heavy loads, which vehicle has improved road-holding and stability, especially when taking a bend, and, thus, undergoes less wear, without having to resort to work-intensive or expensive measures. To this end, the vehicle according to the invention is characterised by the features as further outlined in claim 1. In adjusting the length of the reaction-force elements according to the chosen variation of the direction of motion, the rigid axle also turns in the desired direction of motion. In applications in, for example, buses or trucks (in particular the multiple-axle trucks intended for heavy loads), very large forces arise not only in the chassis but also in the rotation and support-points of the suspension of the known axle, particularly when taking a bend. These forces occur to a much lesser extent in the vehicle according to the invention, in which vehicle the rigid axle also moves at least to some extent with the direction of motion of the vehicle. The drivability, road-holding and stability of the vehicle according to the invention, in which vehicle the rigid axle also moves at least to some extent with the direction of motion of the vehicle. The drivability, road-holding and stability of the vehicle according to the invention are hereby improved; above all, the manoeuvrability is hereby increased, due to the fact that the mobile rigid axle also determines the required direction of motion of the vehicle. It is also an advantage that, if desired, existing vehicles can be converted into vehicles according to the invention in a relatively small-scale operation. This is achieved by replacing the usual rigid reaction-force elements by elements whose length can be smoothly adjusted by, for example, hydraulic, pneumatic or electrical means. In practice, it has transpired that adjustment of the rigid axle of the vehicle when taking a bend is not a necessity at all possible speeds which the vehicle can attain. This fact is exploited in one preferred embodiment of the vehicle according to the invention, which embodiment is characterised by means which deliver a speed-dependent signal which depends on the speed of locomotion of the vehicle, which signal, together with the motion-dependent signal, is fed into a processing device. The said processing device will only pass on the motion-dependent signal to the length-adjustable reaction-force elements if the speed of locomotion of the vehicle is less than a particular adjustable value. In one preferred embodiment, the vehicle according to the invention is characterised by the fact that the said adjustable value is of the order of 30 km per hour. In practice, this value appeared to be quite satisfactory, since trucks take the majority of bends at relatively low speed and making the rigid axle adjustable at speeds higher than this places even higher demands on the reaction-force elements and the chassis. In a preferential embodiment, the vehicle according to the invention is characterised by the fact that driving means are connected to the rigid axle. An advantage is that the said driving means do not have to have any particular form in order to adjust the rigid axle, since the present-day driving means in heavy vehicles already include, in general, a cross-clutch, which not only allows the rigid axle to be adjustable but also allows simultaneous adjustment of the rigid axle and contraction/extension of the rigid axle with the help of fitting springing media. In another preferential embodiment, the vehicle according to the invention is characterised by the fact that the rigid axle is mounted in bearings at a rotation point which is almost centered on the adjustable (and possibly drivable) rigid axle, the said rotation point having bearing means which allow rotation of the rigid axle in at least two planes. The advantage of this further embodiment of the vehicle according to the invention is that it makes possible a desired motion of the rigid axle. In a simple embodiment, the bearing means include a ball bearing. In yet another ensuing preferential embodiment, the vehicle according to the invention is characterised by the fact that the maximal angular displacement (A) which is to be brought about by adjustment of the rigid axle is, when measured with respect to the unadjusted position, smaller than the maximal angular displacement (B) which can be achieved with a controllable forward axle. The advantage of this preferential embodiment of the vehicle according to the invention is that it has appeared to be unnecessary to exactly match the adjustment of the controllable forward axle (which is usually present) to the adjustment of the rigid rear axle of the vehicle. In this way, no very strict demands are made of the accuracy of the degree of correspondence between the adjustments of the respective shafts. Special constructions relating to, for example, suspension, driving, stability, etc., are thus, in principle, unnecessary. The relation between the angular displacement of the rigid axle and the angular displacement of the forward axle (in particular, the controllable forward axle) which is to be decided by the manufacturer is preferably decided on grounds of steering geometry, whereby the necessary media (pneumatic, hydraulic or electric, for example) for maintaining the said relation take a relatively simple form. The invention shall be further elucidated using the figures, in which similar elements are labelled by the same reference numbers. The subjects of the figures are as follows: Figure 1 is a schematic rendition of a possible embodiment of an adjustable rigid axle with a regulator system for application in the vehicle according to the invention; Figure 2 is a schematic plan of a vehicle according to the invention in which the principle of figure 1 is applied and in which the rigid axle is shown in three positions; Figure 3 is a depiction of an end view of the vehicle according to figure 2; and Figure 4 is a rear view of the depictions in figures 2 and 3. Figure 1 shows schematically how a rigid axle 1, which is mounted in bearing means 2 and which is provided with wheels/wheel units 3, is adjustable via reaction-force elements 4. Adjustment with the aid of the reaction-force elements 4 leads to motion of the rigid axle 1 about an axis which is perpendicular to the plane of figure 1. It goes without saying that the embodiment also allows a springing motion of the wheels 3 in a plane perpendicular to the drawing. The axle 1 is rigid in the sense that the positions assumed by the wheel units 3 (which can rotate about the rigid axle 1) are fixed with respect to the rigid axle 1, so that the axle 1 and wheels 3 can only be adjusted together. The reaction-force elements 4 can, for example, be embodied as elements whose length is hydraulically, pneumatically or electrically adjustable. Figure 1 shows an embodiment in which the length-adjustment of the reaction-force elements 4 occurs under the influence of a gas or liquid-displacement. If so desired, this allows a large force to be developed for adjustment of the rigid axle. The elements 4 shown herein possess a plunger 5 and a cylinder-space 6 in which the plunger 5 can be moved. The plunger 5 is connected to the rigid shaft via a plunger rod 7. This connection, which is only schematically depicted, shall in general be somewhat hinge-like, so as to ensure that no overly large unwanted forces develop when the plunger 5 moves in the cylinder-space 6. Above the plunger 5 is located a space 8 where the pressure in a medium can be lowered or raised. In general, simultaneously raising/lowering the pressure in space 6 and lowering/raising the pressure in space 8 will cause the plunger to move. In the depicted embodiment, the spaces 6 and 8 are mutually interconnected by means of the pipes 9 and 10. The pipes 9 and 10 are connected to a processing device 11 which arranges fitting displacements of the medium in pipes 9 and 10 so as to displace the plungers 5. The processing device 11 is connected to means 12 which produce a signal which is a measure of the chosen change in the direction of motion of the vehicle. The means 12 constitute an appliance, such as a steering wheel, joystick, etc., which determines the desired direction of motion of the vehicle and passes this on to the processing device 11. In what is to follow, this appliance will be referred to as the Control Command Unit (CCU). This signal can either be derived directly from the position adopted by the CCU, or it can be derived by indirect means from the position of the controlable forward shaft of the vehicle. The processing device 11 shall be suitably equipped by the expert with whatever means he judges to be necessary to enable it to convert the recieved electrical signal (dependent on the direction of motion) into suitable pneumatic or hydraulic signals in the pipes 9 and 10. Media 23 are connected to the axle 1 and to the processing device 11, which media include an angle recorder (which, for example, is embodied as a steering wheel) which is used to translate the momentary position of the axle 1 into an electrical signal to be used by the processing device 11. Figure 1 shows means 13 which are connected to the processing device 11 and which provide the device 11 with a signal which is dependent on the speed of the vehicle. In general, the media 11 contain a microprocessor (which is not further depicted) which functions as a regulating circuit for the elements 4 and to which the signals from the respective means 12, 13 and 23 are passed. The signal provided by the media 12 contains the desired value concerning the desired direction of motion of the vehicle, whereas the signal provided by the means 23 represents the actual adjusted and measured value determined by the state of the axle 1. Taking the form of a regulator circuit, the processing device 11 is equipped to send a signal to the reaction-force elements 4, which signal shall only be a measure of the desired length-adjustment of the reaction-force elements 4 if the speed of locomotion of the vehicle is less than a certain (generally electrically) adjustable value. In practice, a programmable value which corresponds to 30 km per hour appeared to be favourable. In this way, the manoeuvrability of the vehicle's chassis is improved to an extent which is sufficient in practice, and at least the very greatest wear is reduced. If so desired, the reaction-force elements can also be electrically or electromechanically embodied, whereby motion of the rods 7 is effected, for example, with the aid of a motor-driven worm-wheel. Another alternative is the choice of an electromechanical converter to adjust the rigid axle 1. The working of the embodiment shown in figure 1 is such that, on the basis of the desired direction-of-motion dependent signal from the means 12, and the measured value supplied by the media 23, the position of the rigid axle 1 is continually influenced if the speed of the vehicle lies under a certain minimum value. Figures 2, 3 and 4 show a top view, side view and rear view, respectively, of the manner in which one of the principles discussed up to now is implemented in a vehicle. The figures depict a chassis 16 from which the rigid axle 1 is in (generally sprung) suspension. At its approximate middle point, the rigid axle 1 is mounted in the bearing means 2, which bearings are embodied, for example, as ball bearings. The said bearing means can permit both the springing motion of the axle 1 and the motion associated with adjustment of the axle 1. Figure 3 shows that both the extremity 17 of the element 4 and the other extremity 18 of the element 4 are connected in a hinge-like manner to the chassis 16 and the axle 1, respectively. Despite the fact that the rigid axle 1 is adjustable, it is made drivable by means of a differential 19 mounted between the wheels 3, the said differential being provided with a driving shaft 20. A cross-clutch 21 is mounted between the differential 19 and the driving shaft 20, thus allowing simultaneous driving, springing and adjustment of the rigid axle 1. As shown to best advantage in figure 2, the drivable rigid axle 1 can form the rearmost axle of a possible combination of mutually parallel rigid axles connected to the chassis 16. An axle 22 is also depicted. Driving means 19, 20, 21, and a cross-clutch 24 are mutually interconnected in series and are also connected to the axle 22. In general, the vehicle possesses a controllable forward axle. If the maximal angular displacement of the rigid axle 1 is denoted by A and the maximal angular displacement of the controllable forward axle (assuming such to be present) is denoted by B, then, in most cases, it will be preferable to have A smaller than B. In this case, the forces which arise when the vehicle takes a bend will be significantly limited in magnitude, thus reducing what has to be endured by, in particular, the chassis 16. In general, a desired programmable relation (of steering-geometric nature, for example) will exist between the adjusted angular displacement of the shaft 1 and the desired angular displacement which is stipulated by the CCU 11. Variations of the preceding embodiments occurring naturally to the expert are taken to be covered by the protection rights pertaining to the following claims.

Claims: Vehicle provided with a chassis (16) with suspended axles (1), at least one of which is a suspended rigid axle (1), the said suspension including at least one force element (4), at one hand connected to the chassis (16) whose length can be momentarily adjusted according to a motion-dependent signal which is a measure of the desired change in the direction of motion of the vehicle, said vehicle being characterised in that the force element is a reaction force element (4) which is at the other hand directly connected to the suspended rigid axle (1), and that the length of the reaction-force elements (4) can be momentarily adjusted so as to steer the suspended rigid axle (1) according to a motion-dependent signal. Vehicle according to claim 1, characterised by the fact that the vehicle is provided with means (13) which furnish a speed-dependent signal which depends upon the speed of locomotion of the vehicle, whereby said speed-dependent signal, together with the motion-dependent signal, are fed into a processing device (11), which processing device (11) will only allow the length-adjustable reaction-force elements (4) to access the motion-dependent signal if the speed of locomotion of the vehicle is less than a certain adjustable value. Vehicle according to claim 2, characterised by the fact that the adjustable value is of the order of 30 km per hour. Vehicle according to one of the claims 1 to 3, inclusive, characterised by the fact that the vehicle has driving means coupled to the rigid axle (1). Vehicle according to one of the claims 1 to 4, inclusive, characterised by the fact that the rigid axle (1) is mounted in bearing means (2) at a rotation point which is almost centered on the adjustable, and possibly drivable, rigid axle (1), the said rotation point containing bearing means (2) which allow motion of the rigid axle (1) in at least two planes. Vehicle according to claim 5, characterised by the fact that the bearing means (2) contain ball bearings. Vehicle according to one of the claims 1 to 6, inclusive, characterised by the fact that the reaction-force elements (4) are attached to almost diametrically opposite extremities of the rigid axle (1). Vehicle according to one of the preceding claims in which claim 2 is referenced, characterised by the fact that the means (13) include electronic means for the purpose of producing an electric speed-dependent signal, that there is provided further electronic means (12) for the provision of an electric signal which contains information about the desired direction of motion of the vehicle, that the processing device (11) contains a calculating device, whereby into the said calculating device are fed at least the speed-dependent electric signal and the motion-dependent electric signal, and the calculating device delivers a signal which, in the event of the speed-dependent signal's indicating that the vehicle's speed lies under a certain limit, contains information about the desired direction of motion of the vehicle, that the reaction-force elements (4) are connected to the said calculating device and are embodied in such a way that, on the basis of the information contained in the electric signal provided by the calculating device, a change in length occurs in the reaction-force elements (4) which corresponds to the desired change in the direction of motion of the vehicle. Vehicle according to claim 8, characterised by the fact that the reaction-force elements (4) are embodied as means whose length can be adjusted electrically, pneumatically, mechanically or hydraulically. Vehicle according to claim 8 or 9, characterised by means (23) which take the form of an angle recorder and which are connected to the rigid axle (1) and the processing device, their function being the provision of a signal which is a measure of the adjusted position of the rigid axle (1). Vehicle according to one of the claims 1 to 10, inclusive, characterised by the fact that the maximal angular displacement (A) which can be achieved by adjustment of the rigid axle (1) when measured with respect to the non-adjusted position is smaller than the maximal angular displacement (B) which can be achieved with a controllable forward axle. Vehicle according to claim 11, characterised by the fact that there is a programmable relation between (A) and (B). Vehicle according to one of the preceding claims, characterised by the fact that the vehicle has multiple rigid axles (1) which are drivable via series-connected respective driving means (19, 20,21), whereby at least one of the rigid axles (1) of the vehicle contains reaction-force elements (4) for adjustment of at least that one rigid axle (1) or axles, if there are indeed more than one. Vehicle according to claim 13, characterised by the fact that the vehicle possesses a controllable forward axle, and also possesses a rigid rear axle (1) which is connected to the controllable forward axle.

Inventors: DE ZAAIJER RICHARD JOHANNES WI, OOME PETRUS HUBERTUS ADRIANUS, VAN NEERBOS TEUNIS, DE ZAAIJER, RICHARD JOHANNES WILHELMUS, OOME, PETRUS HUBERTUS ADRIANUS MARIA, VAN NEERBOS, TEUNIS
Applicants: GINAF TRUCKS BV, GINAF TRUCKS B.V.
Application year: 1991
Main classification: B62D13
IPC codes: B60G9, B60B35, B60G17, B62D13