Lifting unit for vehicle wheels and method for using the same

The present invention relates to a lifting unit for vehicle wheels and to the method for using the same.

During the mounting and removal of tires on and from wheels and during subsequent balancing, workers in this field find themselves daily and repeatedly lifting and lowering wheels of different sizes and types, however all considerably heavy.

In particular, the most energy-consuming operations are the removal of the tire-fitted wheel from the platform of the tire changing machine, the transfer of the wheel onto the flanged shaft of the balancing machine, and its subsequent transfer to the vehicle hub for refitting.

This operation, repeated on the average four times for each vehicle, adds up, over the working day, to a considerable effort.

Statutory provisions concerning workplace conditions have also noted the problem and have set a limit to the maximum weight that each operator can lift in performing the above work.

In order to comply with these statutory provisions and also in view of the natural propensity to lighten the physical work of operators in the field, different kinds of wheel lifting unit have been devised which, by replacing the operators in lifting or transferring the wheels among the various machines allow to reduce considerably the overall human energy expenditure.

These conventional lifting units essentially consist of a base chassis which is optionally provided with wheels for moving on the ground and supports a turret along which two cantilevered arms slide so as to converge or diverge; these arms are actuated in different manners and are provided with clamping elements which are adapted to pick up a wheel from the ground, clamp it between the clamping elements, and position it with respect to the couplings of these machines.

The movements of the arms are such that in a first case wheel clamping and the centering of its axis, for example, with respect to the hub of a balancing machine on which the wheel is to be fitted occur simultaneously; in a second case, the wheel is first clamped and then centered on the hub.

The lifting unit, provided with wheels, can of course also be used to transfer and position the wheels with respect to the hubs of the vehicles on which they are to be fitted.

The aim of the present invention is to solve the above-described problems of the prior art by providing a lifting unit for vehicle wheels and a method for using it which allow to perform all the most energy-intensive operations for lifting and transferring the wheels to and from machines in a practically automatic way and so as to minimize the use of physical energy by operators.

This aim and other objects are all achieved by a lifting unit for vehicle wheels, characterized in that it is constituted by a chassis for supporting means with two degrees of freedom for lifting and horizontally transferring wheels to or from machines, the means being controlled by a wheel diameter detector which co-operates with an element for limiting the vertical stroke of the lifting means.

Advantageously, the method for using the unit for lifting vehicle wheels from a low-level supporting surface to levels at which working elements of machines are arranged is characterized in that it consists in loading a wheel onto the lifting unit, in detecting its diameter by means of a detector, and in simultaneously arranging a limiter at a preset level, in lifting the wheel to an elevated level, for example of a platform of a contiguously located tire changing machine, in reloading the wheel onto the lifting unit, in descending to an intermediate level which is defined by the limiter and coincides for example with a rotating shaft of a balancing machine arranged contiguously and opposite the tire changing machine, and in depositing the wheel onto the low-level supporting surface.

Further characteristics and advantages will become apparent from the following detailed description of a preferred embodiment of a lifting unit for vehicle wheels, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

• Figure 1 is a schematic side view of the lifting unit for vehicle wheels according to the invention;
• Figure 2 is an enlarged-scale detail view thereof;
• Figure 3 is a detail view of a limiter;
• Figure 4 is a schematic top view of the lifting unit according to the invention.

With reference to the above figures, 1 designates a lifting unit for vehicle wheels 2, which is constituted by a chassis 3 which supports means 4 with two degrees of freedom for lifting the wheels 2, and means 5 for horizontally transferring the wheels, towards or away from machines (not shown for the sake of simplicity).

The means 4, described in greater detail hereinafter, are controlled by a detector 6 for detecting the diameter "D" of the wheels 2, which co-operates with an element 7 for limiting the vertical stroke of the lifting means 4.

The means 4 for lifting the wheels 2 and the means 5 for moving them horizontally are constituted by a horizontal cross-member 8 which can be moved vertically parallel to itself, is actuated by means of actuation elements 9 and is guided on means 10 which are rigidly coupled to the chassis 3.

A bracket 11 for supporting the wheels 2 is in turn fitted on a front face of the cross-member 8 so that it can slide freely horizontally, for example by pushing; an eccentric body 12 which can be detected by the limiter 7 is fitted on the rear face of the cross-member 8.

The means 10 for guiding the cross-member 8 are constituted by two vertical and parallel columns on which corresponding sleeves 14, rigidly coupled to the rear face of the cross-member 8, engage so that they can slide.

The bracket 11 has, on its upper supporting surface, means 15 for retaining the wheels 2; these means are constituted by an applied member 16 which is rigidly coupled to the surface and is cradle-shaped.

The elements 9 for actuating the vertical movement of the cross-member 8 are constituted by at least one fluid-driven cylinder 17, which is interposed between a carriage 18 which is vertically movable and the supporting chassis 3; the carriage 18 is provided with guiding elements 19 for at least one first section of chain or toothed belt 20, of which one end is rigidly coupled to the chassis 3 while the other end is rigidly coupled to the cross-member 8.

The means 6 for detecting the diameters "D" of the wheels 2 is constituted by a protruding arm 21 which lies above the means 4 for lifting the wheels 2 and the means 5 for transferring them horizontally; the arm is articulated to the chassis 3 so that it rotates on a vertical plane, and supports, at its free end 21a, a feeler 22 for the tread of the tire of a wheel 2; the arm is further provided, at its opposite articulation end, with means 23 for detecting angles of rotation between a reference position, for example a vertical "zero" position, and a position in which contact with the tread occurs; the detection means 23 are connected, by virtue of transmission elements 24 and with preset transmission ratios, to the limiter 7 of the vertical stroke of the lifting means 4.

The transmission means 24 are constituted by a second section 25 of chain or toothed belt which is closed in a loop on a sprocket 26 which is keyed coaxially on the articulation pivot 27 of the arm 21 and on two guiding idler sprockets 28 which are mounted so that they can rotate freely on a bracket 29 which is rigidly coupled to the chassis 3.

A further sprocket 30 is rotationally engaged in an intermediate portion of a segment of the second section 25 of chain or toothed belt and is fitted so as to rotate rigidly at the end of a lifting arm 31 which is in turn articulated to the chassis 3 and rotates on a vertical plane; the opposite end of the arm 31 is connected to the element 7 for limiting the vertical stroke of the lifting means 4.

The limiter 7 is constituted by a slider 32 which is fitted, so that it can slide vertically, on a guide 33 of its own which has a polygonal cross-section and has, on one side directed towards the cross-member 8, a switch 34 for contact with the eccentric element 12.

In a possible and planned embodiment of the lifting unit 1, the transmission means 24 can be constituted by an electronic element for detecting angular movements, for example an encoder, which is arranged on the articulation end of the arm 21 and drives a fluid-driven actuator for moving the limiter 7 vertically.

The operation of the invention is as follows: the lifting unit 1 is preferably arranged between two conventional machines, a tire changing machine and a wheel balancing machine.

An operator then places a wheel 2 vertically on the bracket 11, which has been brought to ground level; the wheel is retained on the bracket by the cradle-shaped applied member 16.

The operator grips the arm 21 and moves it into contact with the highest point of the wheel 2; the rotation of the arm also turns, by means of the section of chain 25 wound around the sprocket 26 and engaged on the sprocket 30, the arm 31, whose free end is connected, for example by means of an additional chain segment designated by the outline 35 in the drawings, to the slider 32, making it slide upwards on the guide 33.

It is observed that the transmission ratios between the sprockets 26 and 30 is such that the breadth of the rotation angle of the arm 21 is twice the breadth of the rotation angle of the arm 31.

By means of a command, the operator activates the fluid-driven cylinder 17, which by extending pushes down the carriage 18, which by contrast lifts the bracket 11, which is loaded with the wheel 2, until it reaches the higher level at which the rotating platform of the tire changing machine is arranged.

The operator then moves the bracket 11 horizontally on the cross-member 8 and moves the wheel 2, without therefore having to lift it further, towards the platform, on which it is rested and on which the conventional operations for removing and refitting the tire on the wheel are performed.

After these operations have been completed, the operator arranges the wheel 2 vertically on the bracket 11 and again activates the fluid-driven cylinder 17, which retracts and draws towards it the carriage 18, ultimately causing the bracket 11 to descend to the ground until the eccentric element 12 interacts with the switch 34 supported by the slider 32, arranged earlier at the level for detecting the diameter of the wheel.

Descent stops and the wheel 2 finds itself arranged so that its center is aligned with the axis of the rotation shaft of the balancing machine.

The operator pushes the bracket 11 so that it slides on the cross-member 8 and inserts the shaft in the central hole of the wheel 2, which is then fixed to the shaft in a conventional manner and balanced.

Once the operation is completed, the wheel 2 is removed from the shaft and returned onto the bracket 11, which through another command is returned to ground level and unloaded.

In practice it has been observed that the above-described invention achieves the intended aim.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

All the details may further be replaced with other technically equivalent ones.

In practice, the materials employed, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claims.

The disclosures in Italian Patent Application No. MO99A000041 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.