CS9100244A2 - Device for pneumatic tyre's stiffness regulation and vehicle equipped with such a device - Google Patents

Abstract

The apparatus of the invention can cause the tyre 10 to function in two different conditions as desired: a rigid mode procured by a tyre 10 completely filled with water, or a soft mode procured by connecting to the tyre 10, through a connection valve 14, a hydropneumatic unit 15 containing a volume 16 filled with a pressurising gas which, owing to its compressibility, procures the necessary softness. <IMAGE>

Description

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BACKGROUND OF THE INVENTION The present invention relates to tire stiffness for use in particular in tires fitted on fork lift trucks or on construction loaders. Tire adaptation to fit fork lift trucks has been a success. Yet the problems are still pending. These problems are essentially due to the sometimes inadequate stability of the truck equipped with tires when the forks are in a very high position when they lift the load up to several meters in height. In this arrangement, the underfoot of the tires, coupled to the vertical distance of the vehicle, is converted to move the carriage in a series of forward and backward or left and right, which are sometimes unsafe, as there is a risk of tipping over the carriage. In addition, these vibrations are at least extremely uncomfortable for maneuvering loads.

Of course, these movements can be limited if they are driven without sudden control movements. However, this is a patient's overall performance and, moreover, the carts still do not contain sufficiently advanced controls to limit these undesirable vibrations. The basic problem to be solved by the invention is to align the benefits of the tire in terms of its price, forward resistance, durability, rolling filter vibration, adhesion, with specific hoisting tires when the lift truck is raised. load to high altitude.

It is already known to increase the stiffness of tires used by lift trucks by either filling with polyurethane or using reinforced air chambers. However, all of these solutions lead to tire tires getting closer to the full hoop and losing much of their own benefits. In a classic tire, when the deflection increases, the tire pressure remains substantially constant. Increasing the load it bears necessarily causes an increase in the contact surface. The significant increase in the transmitted load, resulting, for example, in the transfer of the load, must necessarily result in a significant increase in deflection. Thus, the stiffness of a conventional tire is very weak and that is the property that ensures good comfort of its use.

If it is desired to increase the vertical stiffness of the tire, this results in an increase in load with a much smaller sag deflection. The invention therefore proposes a means for increasing the pressure of a tire with its squeezing much more quickly in conventional tires.

According to the invention, a tire stiffness regulating device mounted on a bicycle comprising a ring, wherein the tire and the tire define the inner volume of the tire, filled with an almost completely compressible fluid, characterized in that it comprises a connecting slide capable of either holding said internal volume insulated or joining with at least one hydropneumatic block, the hydropneumatic block comprising, at the sides of the separating membrane, a volume filled with pressurized gas and a volume filled with the same incompressible fluid, said coupling slide providing, when in the inner tire-to-hydropneumatic block, the inner volume of the tire with said volume filled with non-compressible fluid through lines filled with the same non-compressible fluid, the apparatus comprising means for adjusting the connecting slide.

In particular, it is proposed to provide forklift trucks, which allow the load to be raised to a height, with the tire stiffness control as just described, at least on each of the axle wheels of the furthest fork in order to handle the lift of the lift truck.

To achieve a very high stiffness, fill the inside of the tires with an incompressible fluid. This may be, for example, water or glycol if very low freezing temperatures are required. When the tire is compressed, its volume becomes very light with respect to its initial volume.

This is manifested in the case of inflated air by slightly increasing the internal pressure by several tens of millibars according to the initial conditions. As an example, if the tire 225/75 R 10 XZM is considered unloaded, inflated with air pressure of 1 MPa, its pressure is changed to 1.038 MPa when a load of 4475 kg is applied. The internal volume variation corresponding to this pressure change is 1.06 liters, i.e. 3.3%. If we now fill the tire with an incompressible fluid such as water, the volume variation will not be absorbed by the internal fluid. The tire reinforcements will stretch to keep the tire at a constant volume. The tension in the stiffeners is greatly increased, and as a result the internal pressure of the fluid is greatly increased by the balance of the internal forces of the tire.

Thus, the load will change very quickly for a small increase in the squeezing of the tire, a characteristic of very high rigidity.

Of course, if this use of the tire makes it possible to solve the stability problems posed by forklift trucks, the advantages of the tire, in particular in terms of comfort and resistance to forward movement, are of course lost. It was stated experimentally that the tire became really rigid only under the condition of its full filling with water. In contrast, if there is a bit of air inside it, its radial stiffness is very close to that of the tire inflated with air only.

Accordingly, the invention permits to obtain a variable rigidity using a tire completely filled with water or any other non-compressible fluid, mentioning as appropriate the sufficiency with an air volume sufficient to give it a stiffness comparable to that of a tire inflated with air. The means for actuating the coupling slide may require the intervention of the driver of the truck so equipped, or may be automated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and 2 schematically illustrate the principle of the invention and FIGS. 3 and 4 show the application of the invention on a lift truck. 5

Figures 1 and 2 show a tire 10 fitted with wheel guides 11, pipes 12 and 13, a slide valve 14, and a hydropneumatic block 15 containing a volume 16 filled with a pressurizing gas such as air or nitrogen. Also shown is a valve 17 permitting the supply of pressurized gas to volume 16. The inner volume 18 of the tire is completely filled with an incompressible fluid which also fills the conduits 12 and 13 and the volume of the 19-pneumatic block 15 separated from the volume 16 by the membrane 20.

Of course, according to the invention, some air may be left inside the inner volume of the tire. It is also possible to combine the inner volume of the tire with several hydropneumatic blocks depending on the required rigidity development. All these adjustments are matters of merit depending on the desired application. For example, it is possible to use several hydropneumatic blocks with the same volume of pressurizing gas and to increase the number of these hydropneumatic blocks in contact with the inner volume of the tire to reduce rigidity. When applied to a lift truck, the incompressible fluid preferably fills the entire inner volume of the tire and only a single hydropneumatic block is used, the connecting slide swinging between the closing position and the contacting position between the hydropneumatic block and the inner tire volume . Preferably, the connecting slide and the hydro-pneumatic block are rigidly connected to the wheel. It is possible to install electromagnetic control of the connecting slide. In this case, the need to install the rotatable joints between the inner tire volume and the hydraulic block is eliminated. In a very preferred embodiment, the hydropneumatic block is formed in a cavity forming an integral part of the wheel, for example formed between two wheel discs. Alternatively, the hydropneumatic block may be provided in an element located within the tire cavity 1.0, the structure of which is such that the hydropneumatic block is not exposed to the tire internal inflation pressure. This element may be a liner, a shoe blocking device, or a central flange mounted on the ring.

Fig. 3 shows a forklift equipped with forks 51 allowing to change height. The movement of the forks 51, in particular when the load is very heavy, entails a risk of breaking the truck because it forms a part that is capable of being driven by the rest of the truck. Thus, the truck has a tire stiffness control system on all wheels52 for controlling the transverse swing 1 of the cradle, which is the most undesirable phenomenon, may be installed on each of the front wheels, i.e. the nearest wheels. to the forks, the control device to handle it.

In order to provide an automatic transition to the most rigid mode, the gate valve 14 is provided with an electromagnetic signal control by a switch 53. This switch 53 is controlled by the movement of the forks 52 in such a way that the device 7 isolates the inner volume of the tire 10 when the fork 55 exceeds the predetermined height. Each time a substantial tire compliance 10 risks risking a lift maneuver or even a risk that could be the nature of an accident / situation shown in Fig. 4, the lift truck 50 automatically moves to a functional tire mode 10 quite similar to what would be achieved with full arms. When the forks 51 are lowered during travel of the raised carriage 50 (the situation shown in Fig. 3), the maximum comfort provided by the air-inflated tires 10 is automatically obtained.

Accordingly, the invention allows to solve problems specific to the use of forklift tires. The scope of the invention is not limited to the exemplary embodiment described, but may also be applied to other types of vehicles whenever the tire stiffness is desired to change for any reason.

The same as mentioned above can be applied to construction loaders on tires. In this case, such a vibration can occur when the bucket is in the upside position when the loader is close to the truck. In addition to the safety problems that can arise in the same way as forklifts, oscillations can also cause problems with the tumbling accuracy of the bucket when it swings as it can cause sudden sharp contact between the loader and the truck.

In general, it is possible to install a device of the aforementioned type on all vehicles that may be in a similar situation, ie vehicles whose part can be moved and moved relative to the rest of the vehicle.

For automatic control of the gate valve, as a general rule, the use of a system sensitive to the vehicle's functional state. It is possible to ensure that the connecting slide is controlled via a microprocessor programmed in an appropriate manner, receiving signals from sensors of different types, separately or combined, reacting to the longitudinal or transverse acceleration, vehicle speed, stroke control or bucket or pressure control rollers of the displaceable vehicle.

Claims (9)

Are All Goals $ <? 4 'Going \\ PATENT CLAIMS CLAIMS 1. A tire stiffness control apparatus comprising a tire, wherein the tire defines an inner volume of a tire which is filled with a completely or almost completely incompressible fluid, characterized in that it is provided with a connecting slide (14) capable of maintaining said inner volume (18) of tires isolated; or to operate with at least one hydropneumatic block (15), wherein the hydropneumatic block (15) comprises, on one and the other side, a partition membrane (20 / volume / 16) filled with pressurized gas and a volume (19) filled with the same incompressible fluid, 14 / provides, when in the internal volume joining position (18) with the hydropneumatic block (15), said inner volume (18) of the tire (10) with said volume (19) of pipes (12, 13) filled with the same incompressible fluid and comprising means for actuating the connecting slide. 2. Device according to claim 1, characterized in that the connecting slide (14) and the hydropneumatic block (15) are rigidly connected to the wheel (52). 3. Apparatus according to claim 1 or 2, characterized in that the incompressible fluid fills the inner volume (18) of the tire (10) completely, the device comprising a single hydropneumatic block (15) and one connecting slide (14) extending between the two. the position of the closure and the position ensuring contact between the hydropneumatic block (15) and the internal volume (18) of the tire (10). 4. Apparatus according to claim 2, wherein the hydro-pneumatic block (15) is formed in a cavity forming a non-part of the wheel. 5. Apparatus according to claim 2 and 3, characterized in that the hydropneumatic block (15) is formed in an element located inside the tire cavity (10), the structure of which is such that the hydropneumatic block is not exposed to the internal inflation pressure of the tire. A vehicle on tires, the part of which is capable of being displaced relative to the rest of the vehicle, characterized in that it comprises a device (14 + 15) according to any one of items 1 to 5 at least on each wheel (52) of one axle. A vehicle according to claim 6, characterized in that the connecting slide (14) is controlled by a system that is sensitive to functional yokes. A vehicle according to any one of Claims 6 or 7, characterized in that it is a lift truck (50) provided with forks (51) permitting height adjustments forming part of the displaceable section, the carriage comprising the device according to item 3 or 4 for at least each round of the axle closest to the forks. Vehicle according to claim 7 or 8, characterized in that the connecting slide (14) is provided with an electromagnetic signal control produced by a switch (53) which is actuated by the movement of the forks 15M, so that the device isolates the inner volume (18) of the tire which then passes into the stiffest condition when the fork (51) exceeds the specified height. 10. Apparatus according to claim 7, characterized in that a construction loader is provided.