Levelling system for motor vehicles

Abstract: The present invention relates to a levelling system for motor vehicles which allows the shaft (X) that hinges a truck body (20) or other loading surface (20') defining a loading structure, to an auxiliary frame (2) defining, or forming part of, the vehicle's supporting structure, to remain horizontal so as to enable the body (20) or loading surface (20') to be used effectively; the levelling system basically includes means (4) for detecting the inclination of the hinge shaft (X) to the horizontal (Z) and means (5) for adjusting the inclination consisting of a bracket or lever (51) placed between the supporting structure and the loading structure, pivoted to a second shaft (Y) and operated on by at least two variable extension elements (52s, 52d) connected to the supporting structure and designed to vary the inclination of the latter in accordance with the readings of the detecting means (4).

Description: The present invention relates to a levelling system for motor vehicles, applicable in particular to industrial vehicles with dump bodies. A vehicle with a dump body has a frame connected to the wheels via the suspension and an auxiliary frame hinged to the frame at a hinge shaft usually located at the rear end of the vehicle. When loose material such as soil, sand and so on needs to be dumped, one end of the body is raised until the angle between the body and the frame is sufficient to allow the material to slide off. This operation may be carried out with the vehicle stationary but in most cases the vehicle is simultaneously driven forward slowly to facilitate the tipping out of the load. When the vehicle, which may be a lorry, a semitrailer or a trailer is on safe, solid ground, for example a flat, tarred surface, dumping operations are usually carried out safely and without problems. When the ground the vehicle is standing on is not level, on the other hand, raising the body to dump the material being carried is difficult and may be very dangerous. In fact, if the wheels of the vehicle, particularly the back wheels, do not have a sufficiently solid support, the vehicle tilts (and rolls about its longitudinal axis) placing more weight on one side of it than on the other. Such situations are relatively frequent and make it difficult to manage the beginning of dumping operations. The solidity of the ground on which the vehicle has to work on is not always easy to judge since the vehicles concerned are used on building sites and landfills, where the surface is covered by a layer of loose material compacted to varying degrees. For this reason, even if the wheels on the rear axle (or axles) may be perfectly level when the vehicle starts dumping, the increased weight bearing on the rear axle may cause the vehicle to gradually tilt to one side as the dumping operation proceeds. Although the tilt angle may be just a few degrees at the base, it is much greater at the top when the dump body is raised and leads to irregular dumping. If the load to be dumped is wet soil or similar material, the dumping operation is even more critical; such materials, once the vehicle is tilted sideways, tend to come loose mainly on the side opposite the tilted side, thus making the load on the vehicle even more imbalanced by increasing the mass weighing down on one side of the axle. As a result, the vehicle becomes much more unstable during dumping operations, creating an obvious hazard for the operator (driver) and the risk of damaging the vehicle itself. Moreover, should the vehicle roll over completely, not only is the driver's life at risk but also the lives of any persons who may be working near the vehicle. Since the dump command is normally given from inside the cab, the drivers of the vehicles often have to work under very awkward conditions: in practice, a driver must dump the load, if necessary by inching the vehicle forward and stopping it alternately, without being able to check the real state of the load or to fully control the dumping operation and while being constantly on guard against the risk of rolling over. At present, the stability of a vehicle during dumping operations, is guaranteed by the strength of the connection between the frame and auxiliary frame, which subjects the vehicle structure to considerable torsional strain. For this reason, the frame and the auxiliary frame must be appropriately constructed but even a strong structure may be insufficient to prevent rolling over or damage in the event of abrupt yielding or subsidence of the ground under the vehicle wheels. Furthermore, in CH-A-605 202 it is disclosed a levelling system for motor vehicles, according to the preamble of claim 1. In particular, this prior document discloses a truck having a rear wheel-carrying chassis frame, on which is mounted a sub frame provided at its rear with a tipping member to which the rear end of the truck body is pivoted for vertical tilting movements. The tipping member can pivot about an axis longitudinally of the chassis frame and the mechanism for that purpose 15 located between the chassis frame and the tipping member. The object of the present invention is to overcome the disadvantages mentioned above by providing a levelling system capable of keeping the shaft that hinges the body to the auxiliary frame substantially horizontal so as to allow loaded material to be safely and easily dumped. The stated object is realized in a levelling system for motor vehicles, according to claim 1. The levelling system disclosed may have an independent control system connected to the existing hydraulic system so as to form a self-contained unit or, in the case of new vehicles, it may be built into the vehicle's hydraulic lift system. As mentioned above, the invention may be ideally applied to vehicles with dump bodies, be they lorries, semitrailers or trailers. In one possible embodiment, the invention may be applied to vehicles with a loading surface, not necessarily a dump body, which is pivoted to an auxiliary frame and which must be kept substantially horizontal. As is better described below, this embodiment applies to so-called long vehicles used for transporting very long or wide loads such as prefabricated girders, to prevent undue torsional stress on the vehicle structures between the portion supported by a tractor and that supported by a trailer. The characteristics of the invention are laid out in the claims below and the advantages of the disclosure are apparent from the detailed description which follows, with reference to the accompanying drawings, which illustrate preferred embodiments of the invention by way of example and in which: Figures 1 and 2 are full rear views of two vehicles equipped with the system disclosed and standing, respectively, on a gradient with the body raised and on level ground with the body lowered; Figure 3 is a side view, with an enlarged detail, of an embodiment of the present invention fitted to a dump truck; Figure 4 shows a possible example of the connections used for the present invention together with a schematic plan view of a lorry; Figure 5 is a wiring diagram of an embodiment of the present invention; Figure 6 is a partial, schematic perspective view of another embodiment of the present invention. With reference to the accompanying drawings, in particular the embodiments shown in Figs. 1, 2, 3, 4 and 5, the levelling system for motor vehicles is used in particular for vehicles with dump bodies. In the embodiments illustrated, the invention is applied to a lorry 1 with a supporting frame 3 and an auxiliary frame that hinges to a body 20 at a shaft X placed at one end of the vehicle 1. In other words, the vehicle has a loading structure, which, in the embodiments illustrated, is defined by the body 20 and a supporting structure (defined by the frame 3 and the auxiliary frame 2) hinged together to permit tipping. To enable the dump body 20 to rotate about the hinge shaft X so as to dump the load, the system envisages lifting means defined, in the embodiment illustrated, by a pair of hydraulic cylinders 22. Fig. 4 shows more clearly the embodiment of the levelling system applied to a lorry with a dump body having its own hydraulic circuit. In addition to controlling the units represented schematically by the block S, the existing hydraulic circuit activates the cylinders 22 which raise the dump body 20. The existing hydraulic circuit includes a pump 83 connected to the power take-off 84 of the vehicle. The pump 83 is connected through a suction pipe 94 to a main tank 95 containing the hydraulic oil needed for the operation of the existing hydraulic circuit. The pump 83 may be operated by a control lever 88, normally located in the cab 10, in such a way as to activate a control valve 82 (through appropriate pipes 87 and 86) connected to the lift cylinders 22 through a pipe 81 and to the tank 95 through a discharge pipe 90. The existing circuit includes a solenoid valve 89 which, as described below, allows a hydraulic controlling circuit of the levelling system disclosed to interact with the existing hydraulic circuit. The levelling system includes means 4 for detecting the inclination of the first hinge shaft X to the horizontal and means 5 for adjusting the inclination. The inclination detecting means may be an instrument consisting of an inclinometer or similar device, designed to provide an output signal, preferably electrical, in accordance with the detected inclination to the horizontal. The means 5 for adjusting the inclination include at least one lever or bracket 51 placed between the frame 3, the auxiliary frame 2 and the body 20 and centrally pivoted on a substantially horizontal pin perpendicular to the first shaft X so as to define a second shaft Y joining the auxiliary frame 2 and the dump body 20. In the embodiment illustrated, shown more clearly in the detail of Fig. 3, the bracket 51 is pivoted to the auxiliary frame 2 supporting the body 20 and connected to the frame 3 through at least two variable extension elements 52s and 52d. Alternatively, in another embodiment of the invention, the bracket or lever 51 may be integral with the frame 3 and movable with respect to the auxiliary frame 2. The variable extension elements 52 are placed opposite each other on both sides of the pin Y and are designed to modify the inclination of the bracket 51 to the frame 3 according to the readings taken by the inclination detecting means 4. The variable extension elements consist of a pair of hydraulic actuators 52s and 52d (for example, hydraulic cylinders) controlled by a hydraulic circuit. The control circuit of the variable extension elements 52 consists of a tank 55 and all the related piping, plus a control unit 93, which is connected at its input at least to the inclination detecting means 4 and at its output to a servovalve 53 connected to the variable extension elements 52, and which is designed to vary the extension of the variable extension elements 52 in accordance with the readings of the inclination detecting means 4. In the embodiment described, since the levelling system is combined with an existing circuit, the hydraulic control circuit of the variable extension elements 52 is equipped with an electro-hydraulic motor 92. As shown in Fig. 4, the hydraulic control circuit of the variable extension elements 52 is connected through control unit 93 and through the aforementioned servovalve 89 to the inclination detecting means 4 and to the existing control circuit of the cylinders 22. In this way, it is possible to automatically lower the dump body 20 when its inclination to the horizontal exceeds a defined angle. This operation corresponds to the stage labelled B in Fig. 5 where the block 22-EV indicates the possible activation of a solenoid valve EV connected to the lift cylinders 22. As shown in Fig. 5, the hydraulic control circuit of the variable extension elements 52 may include at least one warning device 96 (which may be a visual warning device as illustrated or an audible warning device or both). The warning device 96 is preferably located inside the cab 10 of the vehicle 1 so as to warn the driver when the inclination exceeds a defined angle (stage A). The bracket 51 may envisage means for stopping its rotation about the pin Y in such a way as to stop the corresponding rotation of the auxiliary frame 2 about the frame 3. The stopping means may be constituted by the variable extension elements 52 themselves, in which case they must be of the type capable of self-locking under defined conditions when not operating. Alternatively, they may be constituted by at least one actuator 54 connected to a hydraulic circuit and having at least one end 54' that may be inserted into a corresponding seat made in the bracket 51, or by a vertical plate integral with it. As a further safety measure, the hydraulic control circuit of the variable extension elements 52 may be connected to the inclination detecting means 4 and to a circuit controlling the locks 25 on the sides 24 of the body 20 so as to automatically open the sides 24 when the inclination exceeds a defined angle. As mentioned earlier, another possible application is illustrated in Fig. 6 where the supporting structure 3 mounts a thrust bearing 30 on which there is a supporting surface 20'. Between the thrust bearing 30 and the supporting surface 20' there is envisaged (either directly or through other connecting structures) a connection that can rotate about a shaft Y placed longitudinally with respect to the vehicle. The variable extension elements 52 are placed opposite each other on the peripheral portions of the supporting surface 20' so as to keep the load on the supporting surface in a substantially horizontal position. This application may be used for thrust bearings which normally allow swinging motion in one direction only: the present invention can be used to make the thrust bearings "active" when they carry structures such as prefabricated girders. The system must be mounted on both tractor and trailer. The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept.

Claims: A levelling system for motor vehicles applicable in particular to vehicles with dump bodies or loading surfaces, that is to say, having a body (20) hinged at a first shaft (X) located at one end of the vehicle to an auxiliary frame (2) and frame (3) connected to the wheels, with means (22) for driving the said body (20) relative to the said auxiliary frame (2) so as to rotate the body (20) about the first shaft (X) to allow the load of material in the vehicle body (20) to be tipped out, wherein said system consists of means (5) for adjusting the inclination of the body (20) to the horizontal including at least one lever or bracket (51) placed between the said body (20) and the said auxiliary frame (2), centrally pivoted on a substantially horizontal pin (Y) perpendicular to the first shaft (X) so as to define a second shaft (Y) joining the dump body (20) to the auxiliary frame (2), and connected to the frame (3) through at least two variable extension elements (52) placed opposite each other on both sides of the pin (Y) and designed to modify the inclination of the body (20) to the auxiliary frame (2) according to the inclination to the horizontal of the said first shaft (X) detected by detecting means (4) envisaged on the vehicle, characterized in that said detecting means (4) are envisaged on the first shaft (X), and the system includes a hydraulic control circuit for the said variable extension elements (52) connected to the said inclination detecting means (4) and to the control circuit of the said auxiliary frame drive means (22) so as to automatically lower the dump body (20) about said first hinge shaft (X) when the inclination of said dump body (20) to the horizontal exceeds a defined angle. The levelling system according to claim 1 characterized in that the said variable extension elements consist of at least one pair of hydraulic actuators (52s, 52d) controlled by a hydraulic circuit. The levelling system according to claim 2 characterized in that the said variable extension elements (52s, 52d) are hydraulic cylinders. The levelling system according to claim 1 characterized in that it includes a control circuit for the said variable extension elements consisting of a control unit (93), which is connected at its input at least to the inclination detecting means (4) and at its output to a servovalve (53) connected to the variable extension elements (52), and which is designed to vary the extension of the said variable extension elements (52) in accordance with the readings of the inclination detecting means (4). The levelling system according to claim 1 characterized in that it includes a hydraulic control circuit for the said variable extension elements (52) connected to the said inclination detecting means (4) and to at least one warning device (96) located inside the cab (10) of the vehicle (1) and designed to warn the driver when the inclination exceeds a defined angle. The levelling system according to claim 1 characterized in that the said bracket is equipped with means for stopping its rotation about the pin (Y) in such a way as to stop the corresponding rotation of the auxiliary frame (2) about the frame (3). The levelling system according to claim 6 characterized in that the said stopping means are constituted by the said variable extension elements (52) being of the type capable of self-locking under defined conditions when not operating. The levelling system according to claim 6 characterized in that the said stopping means are constituted by at least one actuator (54) being connected to a hydraulic circuit and having at least one end (54') that may be inserted into a corresponding seat made in the bracket (51), or by a rigid vertical plate integral with it. The levelling system according to claim 1 characterized in that it includes a hydraulic control circuit for the said variable extension elements (52) connected to the said inclination detecting means (4) and to a circuit controlling the locks (25) on the sides (24) of the body (20) so as to automatically open the sides (24) of the body (20) when the inclination exceeds a defined angle. The levelling system according to claim 1 characterized in that the said supporting structure includes a thrust bearing (30) and the said loading structure consists of a supporting surface (20') joined together at a shaft (Y) placed longitudinally with respect to the vehicle and in that the said variable extension elements are placed opposite each other on the peripheral portions of the supporting surface (20') so as to keep the load on the supporting surface in a substantially horizontal position.

Inventors: BETTINI MARCO, BETTINI, MARCO
Applicants: BETTINI MARCO, BETTINI, MARCO
Application year: 1996
Main classification: B60P1
IPC codes: B60P1