DESCRIPTION

The present invention relates to a locking device for wheels, in particular for locking wheels adapted to be machined/handled in tyre changing machines for workshops or the like.

The use of tyre changing machines is well known which allow the tyre to be fitted onto and removed from the relevant rim of a wheel for vehicles, for example, for maintenance and/or replacement operations of the rim itself or the tyre.

These tyre changing machines generally consist of a basic structure that supports means for gripping/rotating the wheel rim, provided with a rim locking device, and an arm intended to remove and/or fit the tyre onto/from the rim.

There are different techniques for locking the rim, and therefore the wheel, during tyre fitting/removal.

A first technique involves the use of jaw locking devices directly installed on the supporting plate (or also called plate) of the tyre changing machine on which the wheel rests during tyre fitting/removal. The plate is provided with four automatic jaws which can be manually operated by the operator using a pedal to lock the wheel from any movement. In particular, the jaws are positioned at the apexes of a square and at a distance, one from the other, smaller than the diameter of the wheel rim itself. After the wheel has been positioned on the plate, the operator, by simply pressing the pedal, starts the movement of the jaws towards the internal surface of the rim, thus tightening the rim with such a force to lock it on the plate. The jaw locking device just described above, however, being directly mounted on the plate, is complicated to implement, expensive and impractical if, for example, any maintenance is required, which is why different locking devices have been developed which do not require installation on the plate.

A second technique involves the use of pin locking devices. These devices are normally manually assembled and comprise a pin and a fastening element. Usually these devices require the tyre changing machine to be provided with the plate, on which the wheel rests, drilled with a cavity passing through the centre. This way, the pin of the locking device can be partly inserted into the through cavity of the plate and then the wheel can be fitted on the pin itself. In general, the length of the pin is such that one end portion thereof is outside the rim itself. After the assembly between the pin and the rim has been completed, the fastening element, in this case a nut screw, is mounted by screwing it manually by the operator on the threaded portion of the pin. Screwing in the nut screw allows the locking device to apply a compression force to the rim in order to lock it onto the plate. However, since the locking action of the rim on the plate is carried out manually by the operator by screwing the nut screw in, the force applied by the operator may not be sufficient to ensure safe locking operations.

A third locking technique involves, as disclosed in patent document EP 2 551 131 , the use of a pin and lever locking device. Also in this case, a hollow plate must be present to insert the pin. However, a difference with respect to the second technique is that the locking device described in EP 2 551 131 requires the pin to be firmly attached to the fastening element and that the latter comprises a lever and a truncated cone-shaped body instead of a nut screw. In this case, the lever is movable between a home position and a fastening position wherein, in the home position, the pin is fitted into the rim, while in the fastening position the locking device engages the rim to lock the wheel. In actual facts, the operator, by moving the lever between the two positions, allows the free drop of the pin in the through cavity of the plate and the consequent lowering of the truncated cone-shaped element which tightens the rim towards the plate by applying a compression force on the rim itself. This locking technique, although it does not require any particular manual effort by the operators in charge of the tyre fitting/removal operations, nor high execution times, employs elements that are rather complex to make and assemble and therefore very expensive.

In view of the above, the main object of the present invention is to provide a new type of locking device that, the efficiency thereof being equal, has higher performance, is cheaper and less difficult for operators to use than known locking devices.

The aforementioned object is achieved by introducing a special lever, easy to move manually for the operator which, depending on the positioning angle, allows the rim locking operation for a tyre changing machine or the like. In particular, as will be described in detail below, the operator can, first of all, move the lever to a position that allows the free drop of the pin and then move the lever to a further position for the final tightening of the rim.

The present invention therefore relates, in its first aspect, to a locking device provided with a lever according to claim 1 having structural and functional characteristics such as to meet the aforementioned requirements and at the same time to overcome the drawbacks referred to with regard to the prior art.

According to a further aspect, the present invention relates to a method for locking a vehicle rim on a workshop machine, such as a tyre changing machine or the like, according to any of claims 9-10.

Further characteristics and advantages of the locking device and method made according to the present invention will result from the description below of a preferred example of its embodiment, given as an indication but not limited to, with reference to the attached figures, in which:

Figure 1 shows a front view of a tyre changing machine,

Figure 2 shows a longitudinal view of the locking device according to the present invention,

Figure 3 shows a front view of the pin of the locking device in Figure 2,

Figure 4 shows a front view of the locking assembly of the locking device in Figure 2,

Figure 5 shows an exploded view of the locking assembly in Figure 4,

Figure 6 shows a front view of one of the components of the locking assembly,

Figure 7 shows a front view in use of the locking device in the home position,

Figures 8, 9, 10 show a front view in use of the locking device in the configurations of work. With particular reference to these figures, reference numeral 1 globally indicates a locking device of rims C of wheels R on workshop tyre changing machines or the like.

Generally, a tyre changing machine, as shown in Figure 1 , comprises a perforated plate 2 intended to hold the wheel R during the replacement and/or maintenance operations of the wheel R itself and provided with a through cavity 2a at the point where its centre is located.

With reference to Figure 1 , the locking device 1 is intended to be inserted at least partly into the rim C in such a way as to lock the rim C itself to the plate 2 as will be explained in detail later in this description.

With reference to the example shown in Figure 2, the locking device 1 comprises a sliding pin 3 which is longitudinally extended along a direction Y-Y, in use substantially vertical, on which a locking assembly 4 is assembled, the geometrical and technical characteristics of which will be discussed in detail later in this description.

As shown in the example in Figure 3, the sliding pin 3 has a preferably cylindrical shape and comprises an upper end portion 3a, a lower end portion 3b and an intermediate portion 3c.

The sliding pin 3 is preferably hollow to slide a piston 31 therein which is provided with a bayonet element 32 at the bottom, which is intended to be inserted by shape coupling into the through cavity 2a of the plate 2 during the use of the locking device 1. In fact, the through cavity 2a has a shape substantially similar to the bayonet element 32.

In addition, after the bayonet element 32 has been inserted into the through cavity 2a, the operator can lock the sliding pin 3 to the plate 2 by rotating the bayonet element 32 by means of a knob 30 fastened to the opposite end of the bayonet element 32 of the piston 31.

Preferably, the intermediate portion 3c of the sliding pin 3 comprises a surface deflection 3d and, above this, there is a partly knurled external surface 33 the use of which will be discussed in detail later in the following treatise. Still with reference to the example shown in Figure 2, the locking assembly 4 is fitted onto the sliding pin 3 to slide along the latter and comprises a lever 5, a main cylindrical body 7 and a thrust assembly 8.

The lever 5 is movable between a home position A and one (or more) configuration of work B, C, D, so that the movement of the lever 5 itself operates on the cylindrical body 7 to allow the movement/locking of the latter along the pin 3.

In particular, the configuration of work of the lever 5 comprises three different positions, namely:

release position B,

movement position C, and

thrust position D

Again with reference to the example shown in Figure 5, the main body 7 comprises a locking element 9 intended to prevent and/or allow the reciprocal movement of the locking assembly 4 with respect to the pin 3. In particular, the locking element 9 is movable between: an engagement position wherein the locking element 9 operates on the intermediate portion 3c of the sliding pin 3 to contact the external surface 33 and thus maintain the pin 3 stationary with respect to the locking assembly 4, and a disengagement position wherein the locking element 9 deviates from the external surface 33 to release the pin 3 and allow the latter to move freely with respect to the locking assembly 4.

In fact, as mentioned above, the lever 5 is movable between a home position A and the release position B wherein: in the home position A the lever is released from the locking element 9 so that the latter remains in the engagement position, and in the release position B the lever operates on the locking element 9 so as to allow the latter to move to the disengagement position. In particular, the engagement and disengagement positions of the locking element 9 can be achieved thanks to the presence of a sliding ring 90 arranged, in use, orthogonally to the direction Y-Y and associated with the locking assembly 4.

In the present case, with reference to the example shown in Figure 5, the locking assembly 4 comprises a main body 7 mainly composed of two components suitably assembled to form a single cylindrical assembly sliding along the pin 3. In the present case, the main body 7 comprises an upper disc 71 and a lower disc 72.

The upper disc 71 is intended to support the lever 5 while the lower disc 72 receives the locking element 9.

In detail, the lever 5 comprises a body extended longitudinally along one own axis Y-Y provided with a handle 5a, located at its free upper end portion, and with a lower end portion 6a, 6b intended to be connected to the upper disc 71 of the cylindrical body 7.

For this purpose, the upper disc 71 comprises at least a fin 71 a,71 b fastened to the upper surface of the upper disc 71 for the connection to the lower end portion 6a, 6b.

More specifically, the lower end portion 6a, 6b and the fin 71 a, 71 b are each provided with two respective holes, extended along a direction X1 perpendicular to the direction Y-Y, of which the first hole is for joining each other by means of a screw-bolt connection and the second hole 71 e is for locking the lever 5 to the fin 71 ,71 b by means of a locking device, as will be discussed later in this description.

According to one embodiment, the lower end portion 6a, 6b of the lever 5 may have a cam-shaped surface. More specifically, the lower end portion of the lever 5 comprises two cam-shaped surfaces extending parallel to each other along the axis Y-Y and connected to the opposite sides of the main body 7.

Preferably, the upper disc 71 has a main through cavity 71 c with a diameter substantially corresponding to the diameter of the main pin 3 to receive the latter and arranged centrally between the two fins 71 a, 71 b. Advantageously, the lever 5 is able to rotate around the axis X1 between the home position A and the configuration of work B, C, D.

Advantageously, as will be explained in detail later in this description, the lower end portion 6a, 6b carries out a locking/release function of the movement of the locking device 1 with respect to the pin 3 during the rotation of the lever.

Preferably, the lower end portion 6a, 6b of the lever 5 has an overhanging element 5b facing the direction of rotation of the I ever 5. The overhanging element 5b allows the lever to release the reciprocal movement between the pin 3 and the locking assembly 4 when the lever rotates clockwise during the switch from the home position A to the release position B.

According to one embodiment, the lever 5 as a whole has a substantially curved pattern so that the handle 5a is misaligned with respect to the lower end portion 6a and therefore with respect to the pin 3. In particular, the handle 5a is connected to the lower end portion 6a by means of a central oblique/curved connecting portion.

In the following of the present description and in the following claims, the “clockwise” direction of rotation means the direction shown in Figure 2 with respect to the point of view of an observer who looks at the lever 5 placed to the right with respect to the pin 3.

In the following of the present description and in the following claims, the “counterclockwise” direction of rotation means a direction contrary to the direction indicated in Figure 2 with respect to the point of view of an observer who looks at the lever 5 placed to the right with respect to the pin 3.

Preferably, the lever 5 is made of a single body piece.

With reference to the example shown in Figure 5, the lower disc 72 has a shape that can accommodate the sliding ring 90 inside and its use is closely related to the working position of the lever 5.

In this case, it has a preferably cylindrical shape and comprises a through cavity 72a, an upper surface 72b and a side wall 72c. The upper surface 72b has a depression forming, as a whole, a first ring-shaped surface 72d and a second ring- shaped surface 72e, the latter being lowered in cross-section with respect to the first ring-shaped surface 72d.

Conveniently, on the side wall 72c are formed two cavities 72f, 72g extended as a whole along a radial direction, open upwards and arranged diametrically opposite each other wherein each one is communicating with the through cavity 72a. In particular, the first cavity 72f extends substantially horizontally while the second cavity 72g has a bottom inclined downwards in the direction of the cavity 72a.

Conveniently, below the first cavity 72f, there is a circular opening 72h for the insertion of a spring 91 the function of which will be explained in detail below.

The shape discussed herein of the lower disc 72 allows accommodating the sliding ring 90, in particular, the sliding ring 90 is accommodated on the second ring- shaped surface 72e. This sliding ring 90 has a preferably circular shape with a through cavity 90a which is also adapted to fit the sliding pin 3.

The locking element 9 also comprises a block 92 preferably trapezoidal in shape and connected to the sliding ring 90. The block 92 is preferably fastened below the sliding ring 90 by means of a cylindrical joining element 93, which is intended to be firmly fastened onto the holes 90b and 92a obtained in the sliding ring 90 and in the block 92, respectively.

Conveniently, the block 92 comprises a preferably knurled side surface 92b which faces, in use, the surface 33 of the sliding pin 3. In particular, when the locking element 9 is in the position of use, the side surface 92b adheres firmly to the surface 33 of the sliding pin 3 to lock it.

The block 92 also comprises a lower surface 92c with an inclination identical to the inclination of the bottom of the second cavity 72g. Advantageously, the latter inclination allows easy removal and/or insertion of the block 92 on the sliding pin 3.

Conveniently, the sliding ring 90 also comprises a fin 90c in a diametrically opposite position with respect to the hole 90b. The fin 90c has an inverted“L" shape wherein, at its vertical portion, a through cavity 90d is obtained for the insertion of the spring 91. In particular, when the sliding ring 90 is completely accommodated in the lower disc 72, the through cavity 90d and the opening 72h are arranged coaxially to each other to accommodate the spring 91. The spring 91 allows the block 92, and in particular the knurled surface 92b, to push constantly on the pin 3 to maintain the latter locked with respect to the locking assembly 4. When the lever 5 switches from the home position A to the release position B, the overhanging element 5b pushes the fin 90c to disengage the locking element 9 from the pin 3 and then allow the reciprocal movement between the pin 3 itself and the locking assembly 4.

With reference to the example shown in Figure 8, the configuration of work requires the lever 5 to switch from the release position B to the movement position C, wherein: in the movement position C the lever 5 continues to operate on the locking element 9 so as to allow the latter to remain in the disengagement position.

This way, the assembly 4 is free to slide along the pin 3 towards the wheel R so that the truncated cone-shaped body 81 is partly inserted into the cavity C1 of the rim C.

After the truncated cone-shaped body 81 is inserted into the cavity C1 of the rim C, the operator moves the lever 5 from the movement position C to the thrust position D, as shown in Figure 9, wherein: in the thrust position D the lever 5 releases from the locking element 9, and in particular from the fin 90c, in such a way as to allow the latter to return to the engagement position and, at the same time, the lever 5 operates on the truncated cone-shaped body 81 so that the latter applies a compression force onto the rim C to lock it.

For this purpose, the upper disc 71 has a pair of housings 71 d, arranged around the cavity 71 c, to receive respective thrust pins 74.

Similarly, the lower disc 72 has a pair of housings 72i, 72I, arranged around the cavity 72a, to receive respective thrust pins 74. Advantageously, the pairs of housings 71d and the pairs of housings 72i,72l are, in use, coaxial to each other.

The thrust pins 74 are locked together and fastened to the thrust assembly 8 and, in particular, they overhang upwards from the thrust assembly 8 itself to slide in the housings 71 d obtained in the upper disc 71 and in the housings 72i, 72I obtained in the lower disc 72.

This way, the head portion of each pin 74 exceeds the upper disc 71 to be contacted by the lever 5. In particular, in the thrust position D, the lower end portion 6a, 6b of the lever 5 applies a thrust on each pin 74 to lower them.

According to one embodiment, the thrust assembly 8 forming part of the locking assembly 4 comprises a connecting disc 80 and a truncated cone-shaped body 81. In particular, with reference to the example shown in Figure 6, the disc 80 is provided with a through cavity 80a to partly fit the sliding pin 3 and a threaded surface portion overhanging downwards to tighten the disc 80 onto the truncated cone-shaped body 81. In this particular case, the latter also has a threaded through cavity 81 a intended to couple by shape to the overhanging portion of the disc 80. This way, advantageously, the truncated cone-shaped body 81 can be easily replaced in case of damage and/or change in the diameter of the rim C of the wheel R to be machined.

According to the preferred embodiment shown in the example in Figure 5, the thrust pins 74 are connected to their respective springs 1 1 ,12 which can be positioned in the housings 72i,72l of the lower disc 72. This way, when the lever returns to the home position A, the springs 1 1 ,12 operate on the pins 74 to allow the truncated cone-shaped body 81 to rise and then to finish the thrust action on the rim C.

Advantageously, as shown in the example in Figure 4, the locking device 1 also comprises a fastening device 13,14 which is adapted to lock the lever 5 to the main cylindrical body 7 or, more specifically, to the fins 71 a,71 b of the upper disc 71 , when the lever 5 is in thrust position D.

Conveniently, the lever 5 comprises an additional through cavity 5c located at its lower end portion 6a, 6b and intended to couple by shape to the fastening device 13, 14.

According to the present invention, as shown in Figure 2, the fastening devices 13, 14 may comprise a fin-shaped element 13 or a knob 14. In detail, both the fastening devices 13,14 comprise a locking pin inserted in the cavity 5c of the lever 5 and a spring fitting on the pin itself. In detail, when the lever 5 is in one of the positions comprised between the home position A and the movement position C, the locking pin, inserted in the cavity, exceeds the lower end portion 6a, 6b of the lever 5 in such a way that the pin itself contacts the fin 71 a, 71 b, thus allowing the rotation of the lever 5 itself.

Otherwise, when the lever 5 is in the thrust position D, the through cavity 5c of the lever 5 is in the coaxial position to the hole 71 e of the fin 71 a, 71 b, the spring is released by pushing the locking pin towards the hole 71e of the disc fin 71 a, 71 b. This way, the lever 5 is secured to the main cylindrical body 7 so as to allow the lever itself to maintain the thrust position D.

To allow the reciprocal movement between the fastening device and the pin again, the locking pin can be disengaged from the hole 71 e by means of the fin-shaped element 13 or the knob 14.

A possible method of operation of the locking device 1 according to the present invention is described below.

In particular, as mentioned above, the configuration of work of the lever 5 comprises three different positions, namely:

release position B,

movement position C, and

thrust position D.

The method according to the following invention comprises first of all placing a wheel R on the plate 2 so that the through cavity C1 of the rim C is coaxial to the through cavity 2a of the plate 2.

After that, the operator inserts the locking device 1 into the through cavity C1 of the rim C until the bayonet element 32 is fully inserted into the through cavity 2a of the plate 2, which is substantially similar in shape to the bayonet element 32. Subsequently, the locking device 1 may be locked to the plate 2 by rotating the bayonet element 32 using the knob 30.

Advantageously, in the latter case, the lever 5 of the locking device 1 is in the home position A so that the lever 5 itself is released from the locking element 9 to allow the latter to remain in the engagement position, as previously described. Preferably, each of the above positions corresponds to an angle of inclination of the lever 5 with respect to the axis Y-Y of the sliding pin 3.

In the home position A, the lever 5 is rotated clockwise with respect to the axis Y-Y of the sliding pin 3 in such a way that the lever 5 itself is inclined by an angle a with respect to the pin 3 itself, the value a of which is preferably comprised between 40° and 70°.

Then, after fastening the locking device 1 to the plate 2, the operator rotates the lever 5 from the home position A to the release position B. In the release position B, the lever 5 is rotated clockwise with respect to the axis Y-Y of the sliding pin 3 in such a way that the lever 5 is inclined by an angle b, the value of which is preferably 70° or more.

The inclination of the lever 5 in the release position B allows the lever to contact the locking element 9.

In this case, the overhanging element 5b of the lever 5 pushes the fin 90c of the sliding ring 90 to disengage the locking element 9 from the pin 3 and thus allow the reciprocal movement between the pin 3 itself and the locking assembly 4.

In particular, the block 92 of the locking element 9, as a result of the stress of the lever 5, shifts on the inclined plane of the cavity 72g of the lower disc 72 thus deviating from the external surface 33 to free the pin 3 and allow the latter to move freely with respect to the locking assembly.

This way, the assembly 4 is free to slide along the pin 3 towards the wheel R so that the truncated cone-shaped body 81 is partly inserted into the cavity C1 of the rim C.

Preferably, the sliding pin 3 drops freely towards the plate 2 by a length depending on the length of the pin itself and depending on the width of the tyre.

Then, after the truncated cone-shaped body 81 rests on the rim C, the operator rotates the lever 5 again, preferably in the thrust position D. In the thrust position D the lever 5 is rotated counterclockwise with respect to the axis Y-Y of the sliding pin 3 in such a way that the lever is inclined by an angle y, which has a value preferably comprised between 0° and 40°.

Generally, in the thrust position D the lower end portion 6a, 6b of the lever 5 pushes on the head portion of each pin 74 to lower them.

In this case, the lever 5 releases from the locking element 9 so as to allow the latter to return to the engagement position and, at the same time, the lever 5, operating on the pins 74, allows the disc 80 and therefore the truncated cone- shaped body 81 to slide towards the wheel R to apply a compression force on the rim C to lock it.

Finally, after the tyre maintenance/replacement operations have been carried out by the wheel R, the operator may rotate the lever 5 clockwise again from the thrust position D to the home position A to release the rim C. This happens because the lower end portion 6a, 6b of the lever 5 frees the pins 74 so that the springs 1 1 , 12, by releasing, return the disc 80 towards the main body 7.

As can be seen from this description, it has been ascertained that the described invention achieves the intended objects and in particular the fact is underlined that, by means of the lever locking device described herein, it is possible to lock the rim of a wheel on a workshop machine by means of a device of simple construction and therefore cheaper compared to the already known devices and avoiding particular physical efforts by the operator during use.

In particular, the principle of operation of the device according to the invention provides for one or more fundamental phases, namely: insertion of the sliding pin into the rim C with subsequent fastening in the plate, free drop of the locking assembly until it is inserted into the rim C, and final tightening of the thrust assembly onto the rim C.

The lever is then rotatable clockwise from a home position to a release/movement position and counterclockwise from the release/movement position to a thrust position. This way, it is possible to allow the free drop action of the locking assembly so that the thrust assembly applies a compression force onto the rim, by locking it.