Improved levelling system for motor vehicles

Abstract: A levelling system for motor vehicles, used particularly for vehicles (1) with a dump body (24) hinged, by a first rotation shaft (X) placed at the rear end (11) of the vehicle, to a frame (2,3) connected to the wheels; means of moving (22) the body (24) in relation to the frame (2,3) are provided, enabling the dump body to be rotated in order to dump material contained in it; means of adjusting the inclination consisting of a bracket (51) are positioned between the dump body (24) and the frame (2,3), centrally pivoted on a horizontal pin perpendicular to the first shaft (X), and connected to the frame by at least two variable extension elements (52) designed to adjust the inclination of the dump body in relation to the frame (2,3), in accordance with the readings on the means of detecting the inclination of the first rotation shaft to the horizontal; the improved levelling system includes means of activating the means of adjusting the inclination, including or connected to sensors placed on the motor vehicle control panel and/or on parts of the motor vehicle itself, so that the means of adjusting the inclination are activated when the vehicle 1 is in a certain working position.

Description: The present invention relates to a levelling system for motor vehicles particularly used by industrial vehicles with a dump body, and more specifically to vehicles as defined in the preamble of independent claim 1. Vehicles equipped with dump bodies have a frame connected to the wheels by suspension and supported by an auxiliary frame which is hinged to the dump body pivoted by an axis positioned at the rear end of the vehicle. To dump loose material such as soil, sand etc., the dump body is raised until it reaches an angle in relation to the frame which will enable the dump body to be emptied. This operation can be carried out when the vehicle is stationary but in most cases the vehicle is simultaneously driven forward to facilitate the tipping out of the load. When the vehicle, which may be a truck, 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 stability of the ground on which the vehicle has to work 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, the shifting 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. It is known from document DE 4427886 an inclinometer which measures the rate of rotation of the body of the vehicle in the direction of the inclination angle. The inclination angle is measured in an inertial system by a fibre optical gyroscope and a warning signal is generated when a critical value of the inclination angle is exceeded. Document CH 605202 shows a tipping vehicle provided with a rear tipping member mounted on the chassis for pivotal movement about an axis extending in the longitudinal direction of the vehicle and with drive means for pivoting the rear tipping member. The drive means comprises a thrust piston unit pivotally connected to the rear tipping member and to the chassis. A solution to these problems has been provided by the same Applicant with the invention disclosed in the patent application IT - B095A 000106 (priority document for EP-A-0 732 236), corresponding to the preamble of claim 1. The previous patent application relates to a levelling system which enables the hinged axis between the dump body and the auxiliary frame to remain horizontal, thus enabling the material in the truck to be dumped safely and easily. The levelling system disclosed in the above mentioned application basically includes means for detecting the inclination of the hinged axis between the dump body and the auxiliary frame to the horizontal and means for adjusting the inclination consisting of a pivoted lever or bracket which is acted on by at least two variable extension elements located on opposite sides of the pivot and designed to adjust the inclination in accordance with the readings of the detecting means. The invention disclosed in the present patent application is an improvement on the above mentioned levelling system and enables the levelling system to be handled better due to an improved system for controlling some parts of the motor vehicle and the levelling system. Further characteristics and advantages of the invention 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: Figure 1 is a partial rear view of a motor vehicle equipped with the system disclosed, with some components represented schematically as blocks; Figure 2 is a side view with some details enlarged and represented schematically, of a motor vehicle according to the present invention while in operation; Figure 3 is a full rear view of two motor vehicles with dump bodies showing two possible situations which could occur while operating. The motor vehicle on the left is equipped with the disclosed levelling system and the one on the right is of a conventional type, without a levelling system; Figures 4,5,and 6 are partial rear views of a motor vehicle according to the present invention in different stages of use; Figure 7 is a flow diagram showing how the present invention functions. With reference to the drawings listed above, in accordance with the present invention, 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 truck 1, with a supporting frame 3, and an auxiliary frame 2 that hinges to a dump body 20 by an axis X placed at one end 11 of the vehicle 1. In the following description, for the sake of simplicity, reference will made to a frame 2,3 meaning both the frame 3 and auxiliary frame 2. 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 on the hinge axis X so as to dump the load, the system envisages lifting means defined, in the embodiment illustrated, by a pair of hydraulic cylinders 22. The levelling system includes means 4 for detecting the inclination of the first hinge axis X to the horizontal and means 5 for adjusting the inclination. The means for detecting the inclination are represented schematically in figure 1 by a block 4. They 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 for adjusting the inclination 5 include at least one lever or bracket 51 placed between the frame 2,3 and the dump body 20, and centrally pivoted on a substantially horizontal pin perpendicular to the first axis X so as to define a second axis Y joining the frame 2,3 to the dump body 20. In the embodiment illustrated, between the bracket 51 and the frame 2,3 there are two variable extension elements 52s and 52d. 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 2,3 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 is not shown in its entirety but is represented by a block 50 in figure 1. 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 dump body 20 around the frame 2,3. 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 51' integral with it. The disclosed levelling system has means 50 for activating the means 5 for adjusting the inclination including or connected to a sensor positioned on the controls of the motor vehicle 1 and/or positioned on parts of the motor vehicle 1 itself, in such a way as to enable the activation of the means 5 for adjusting the inclination when the vehicle 1 is in a certain working position, as explained more clearly below. The activating means 50 may be a levelling circuit designed to trigger the means of activation when a certain threshold value is reached detected by the angle detecting means 4. In other words the levelling circuit (not shown in the embodiments because it may be included in the detecting means 4) activates the levelling of the vehicle only when the inclination of the vehicle itself is greater than a certain value in relation to the horizontal Z. This means that they are never activated by the vehicle suspension. Among the vehicle controls, there may be at least one control 12 for a parking break 13 of the motor vehicle 1. In other words the system includes the use of the hand break to start the levelling operation. As stated above, the bracket includes means of stopping its rotation around the axis Y, so that the corresponding rotation of the dump body in relation to the frame 2,3 is stopped, this means consists of an actuator 54 ( or a pair of actuators 54). The system may include sensor means 55 placed, for example at the extreme end 54' and connected to the activating means 50, so that the levelling means are activated when the bracket 51 is not stopped. When the dump body of the vehicle tilts sideways, or when the dump body 20 rotates on an axis K positioned longitudinally along the motor vehicle 1, the system may include sensors 56 to detect the rotation on the axis K, so that a corresponding signal is sent to the activating means 50 so that the activation of the levelling means 5 are disabled in relation to the sideways tilting of the dump body 20. In addition at least one of the variable extension elements 52d has a sensor 57 to measure the value of the distance between the frame 2,3 and the dump body 20, that is to discover the amount by which the dump body 20 has moved in relation to the frame 2,3 so that the correct manoeuvre can be made to return the dump body to the rest position, that is substantially parallel to the frame 2,3 independently of the inclination of the motor vehicle in relation to the horizontal Z. This means that the lower pins 19 of the dump body 20 can be correctly inserted into their corresponding seats 18 on the frame 2,3. A possible example of the way the levelling system disclosed functions is described in the flow diagram in figure 7. In practice the levelling system includes a series of enabling devices in order to balance the vehicle. One of these comes from the hydraulic circuit pressure level being sufficient. Other enabling devices come from; putting on the hand brake 13, stopping the bracket 52, and tilting the dump body sideways (when required). Figure 3 shows the difference in stability derived from the present invention. The angle α in relation to the horizontal on a conventional vehicle (the vehicle shown on the right) causes the whole vehicle to tilt, while on a vehicle with a levelling system it does not tilt so that the dump body 20 stays horizontal. The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept as defined by the appended claims.

Claims: A levelling system for motor vehicles applicable in particular to vehicles (1) with a tiltable dump body (24), the motor vehicle having a dump body (24) hinged, by a first rotation axis (X) placed at the rear end (11) of the vehicle, to a frame (2,3) connected to the wheels; having means of moving (22) the said dump body (20) in relation to the frame (2,3), enabling the dump body to rotate around the first axis (X) to unload the material inside; having means for detecting the inclination of the first axis (X) to the horizontal ; having means for adjusting the inclination including at least one lever or bracket (51) positioned between the dump body (20) and the said frame (2,3) centrally pivoted on a pin substantially horizontal and perpendicular to the said first axis (X), and defining a second axis (Y) joining the dump body and the frame and connected to the same frame by at least two variable extension elements placed opposite each other on either side of the said pin (Y) and designed to adjust the inclination of the said dump body in relation to the said frame, according to the reading of the inclination, on the detecting means (4), of the said first shaft to the horizontal, the levelling system characterised in that it has sensor means for detecting the working position of the vehicle, said sensor means being positioned on the motor vehicle (1) controls and/or on parts of the motor vehicle (1) itself; and means of activating (50) the said means of adjusting the inclination (5), said means of activating including or being connected to said sensor means so that the adjusting means (5) are activated when the vehicle (1) is in a certain working position. The levelling system according to claim 1, characterised in that the said means (50) of activating the said means (5) of adjusting the inclination include a levelling circuit designed to trigger the said means of activation according to a threshold value detected by the angle detecting means. The levelling system according to claim 1, characterised in that said sensor means is positioned on at least one control (12) for a parking brake (13) of the motor vehicle (1). The levelling system according to claim 1, characterised in that the said bracket has means of stopping it from rotating on said pin (Y), in order to stop the corresponding rotation of the dump body (20) on the frame (2,3), including at least one actuator (54) connected to the hydraulic circuit with at least one end (54') which can be inserted in a corresponding seat on the said bracket (51) or by a rigid part connected to it (51') and also in that there are sensor means (55) positioned on the said end (54') and connected to the said means of activation (50) of the levelling means (5), so that the levelling means can be activated when the said bracket (51) is not stopped. The levelling system according to claim 1, applicable particularly to vehicles where the dump body tilts sideways, the vehicle having a dump body (20) rotating on an axis (K) positioned longitudinally along the motor vehicle (1), characterised in that is has sensor means (56) to detect the rotation on the said longitudinal axis (K), designed to send a corresponding signal to the said activating means (50) so that the said levelling means (5) are disabled when the dump body (20) is tilted sideways. The levelling system according to claim 1, characterised in that at least one of the said variable extension elements (52d) has a sensor (57) designed to measure the distance between the frame (2,3) and the dump body (20) or designed to discover the amount by which the dump body (20) moves in relation to the frame (2,3), in such a way as to enable the dump body (20) to manoeuvre correctly when returning to the dump body (20) rest position, which is substantially parallel to the said frame (2,3), independently of the inclination of the motor vehicle to the horizontal (Z).

Inventors: BETTINI MARCO, BETTINI, MARCO
Applicants: BETTINI MARCO, BETTINI, MARCO
Application year: 1997
Main classification: B60P1
IPC codes: B60P1