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Patent Searching and Data

Document Type and Number:
WIPO Patent Application WO/2016/135663
Kind Code:
A self-centering device for tire-changing machines (1) comprising: a turntable (10) for support and fixation of wheels; a plurality of spikes (11), also known as jaws, having a body (17) that defines a base (18) and an opposite engaging tooth (19) and being slindingly arranged on a work surface (10A) of said turntable (10) between an active rim-holding position and an inactive rim-releasing position; means (12) for simultaneous actuation of said spikes (11) from said active position to said inactive position and vice versa; guide means (13, 14) formed in said turntable (10) for guiding said spikes (11); slider means (21, 23) for causing low-friction sliding of said spikes (11) being interposed between said spikes (11) and said turntable (10).

FERRARI, Gino (Via Ascari 8, Correggio, 42015, IT)
MAIOLI, Franco (Via Monache 2, Correggio, 42015, IT)
Application Number:
Publication Date:
September 01, 2016
Filing Date:
February 25, 2016
Export Citation:
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FERRARI, Gino (Via Ascari 8, Correggio, 42015, IT)
MAIOLI, Franco (Via Monache 2, Correggio, 42015, IT)
International Classes:
Foreign References:
Attorney, Agent or Firm:
BERGAMINI, Silvio (Maroscia & Associati S.r.l, Piazza del Castello 26, Vicenza, 36100, IT)
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1 . A self-centering device for tire changing machines (1 ) comprising:

- A turntable (10) whereupon wheels to be fastened are hold and fastened, which has a work-surface (1 OA) and an opposing surface (1 OB);

- A plurality of spikes (1 1 ), also named jaws, each of which has a body (17) defining a base (18) from which and engaging tooth (19) arises and from the opposing side a body extending shoe (20), said spikes (1 1 ) being slindingly arranged on said work-surface (10A) of said turntable (10) between an active grasping position of a rim and an inactive release position of the rim;

- Simultaneously actuating means (12) of said spikes (1 1 ) between said active and inactive positions;

- Guiding means (13, 14) of said spikes (1 1 ) obtained in said turntable (10),

characterized in that said between said spikes (1 1 ) and said turntable (10) low friction slide means (21 , 23) of said spikes (1 1 ) are interposed.

2. A self-centering device as claimed in claim 1 , wherein said guiding means for each spike (1 1 ) comprise:

- A passing-through groove (13) radially obtained in said turntable

(10) and engaged by said shoe (20);

- A box-like shaped rail (14) arranged aligned with said passing- through groove (13) and having a first fastening side to said opposing surface (10B) of said turntable (10) and a second parallel side opposing said first side, said first side having a first longitudinal opening (15) facing said passing-through groove (13) and said second side having a second longitudinal opening (16) parallel to said first longitudinal opening (15).

3. A self-centering device as claimed in claims 1 and 2, wherein said low friction slide means comprise, for each spike (1 1 ), a plurality of first wheels (21 ) freely rotatable mounted bilaterally on said shoe (20) and engaged in said box-like shaped rail (14), said first wheels (21 ) having rotation axes (R) parallel to said work-surface (10A).

4. A self-centering device as claimed in claim 3, wherein said low friction slide means further comprise at least a second wheel (23) housed free to rotate in a bilaterally open space (22) obtained in said shoe (20), said second wheel (23) having a rolling surface projecting bilaterally outside from said space (22) and engaged between the edges of a respective groove (13).

5. A self-centering device as claimed in anyone of preceding claims, wherein said body (17) further has a third wheel (25) which is hold to said shoe (20) with its rotation axis (24) perpendicular to said work-surface (10A) and coupled with said simultaneously actuating means (12).

6. A self-centering device as claimed in 1 , wherein spacing means (31 ) between said wheels to be fastened and said work-surface (10A) are provided for.

7. A self-centering device as claimed in claim 6, wherein said spacing means comprise a plurality of ribs (31 ) obtained / mounted in a fixed / removable manner on said work-surface (10A).

8. A self-centering device as claimed in claim 5, wherein said simultaneously actuating means comprise:

At least a plate (27) rotatably mounted coaxially beneath said turntable (10) and bi-directionally actuated by actuating means (29, 30);

A plurality of holes (26) each of which shapes a cam profile having one end (26A) centripetally oriented and an opposing end (26B) centrifugally oriented and wherein a respective third wheel (25) is engaged, each cam profile being equal to the other cam profiles and having a shape with one end converging to a center of said plate (27) and an opposing end diverging from said center.


Field of the invention

The invention relates to a self-centering device for tire-changing machines, which is generally used for temporarily fixing the wheels to the work turntable of such machines, without damaging their rims.

Background art

Tire-changing machines are known to be equipped with a base having a tool-supporting column extending upwards therefrom, and a substantially horizontal turntable having members for temporary fixation of a wheel for a tire repairer is to work thereupon.

This turntable is known in the art as a "self-centering" turntable and the fixation members consist of four spikes or jaws, which are slidingly mounted to the turntable to slide thereon along paths that converge toward the center in the active holding step and diverge therefrom in the passive releasing step.

Typically, each jaw is slidingly guided in a respective straight slot formed in the turntable; the four slots generally form a cross of slots having two straight, perpendicular diametrical branches.

The jaws are simultaneously actuated by means of pneumatic actuators, which are arranged directly under the turntable, and may be connected through special cam profiles, also accommodated under the turntable, between the underside of the latter and the actuators, and simultaneously drive all the jaws together, in both active and passive directions.

More in detail, each jaw comprises a prismatic body which defines a base designed to directly slide on the surface of the turntable and, opposite thereto, a hook that extends upwards from the base and forms a projecting tooth oriented toward the center of the turntable.

In the active holding step, this tooth fits between the edge of the wheel rims and the beads of the tires mounted to the rims, and in the passive steps it slips out of them.

The base of each claw also has a downwardly-extending stem or pin which extends through the slot by which it is guided and has its lower end directly hinged to the actuators or engaged in a respective cam profile, to receive therefrom, in either case, the motion that ensures its movements along the slot in both active and passive steps.

This prior art suffers from certain drawbacks.

A first drawback is that, as the base of each jaw slides in direct contact with the surface of the turntable, it generates therewith a considerable contact friction force.

This contact friction progressively abrades both the base of each jaw, and the surface of the turntable, and generates a metal powder that, with the passage time and repeated sliding movements, will cover mainly the areas of the turntable upon which the jaws slide, but also the members that drive them, thereby progressively affecting smooth sliding motion and progressively increasing the amount of force required therefor.

A second drawback is that systematic generation of metal powder due to friction between the bases of the four jaws and the surface of the turntable maintains a substantially constant layer of dirt which fouls the wheels that lay on and are fixed to the turntable and anything that might contact the turntable during operation.

A third drawback is that the presence of this dirt requires periodic cleaning of tire-changing machines and the areas around them, which involves some down time of the machines.

A fourth drawback is that the teeth of the spikes, especially in the holding step, during which they fit between the edges of the rim and the beads of the tire mounted thereupon, often violently hit the edges of the rims and damage them.

Disclosure of the invention

One object of the invention is to improve the prior art.

Another object of the invention is to provide a self-centering device for tire-changing machines, which can prevent the generation of metal powders due to friction.

A further object of the invention is to provide a self-entering device for tire-changing machines that ensures integrity of the wheels to be fixed thereupon.

Yet another object is to provide a self-centering device for tire-changing machines that has a very simple and hence highly cost-effective structure.

In one aspect the invention relates to a self-centering device for tire- changing machines as defined in the features of claim 1 .

Further aspects of the invention are defined in the dependent claims.

The invention affords the following advantages:

- preventing direct contact between the bases of the jaws and the surface of the turntables during the sliding movement, and hence preventing the generation of metal powder;

- maintaining the integrity of the wheels fixed to the turntables;

- avoiding the down time associated with the need of cleaning the metal powder;

- protecting all the members of the tire-changing machines that are designed to drive the jaws and rotate the turntables.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent from the detailed description of a preferred, non-exclusive embodiment of a self-centering device for tire-changing machines, which is shown as non-limiting example in the annexed drawings, in which:

FIG. 1 is a general perspective view of a tire-changing machine of the invention;

FIG. 2 is a perspective view of a detail of the tire-changing machine of Figure 1 in a slightly enlarged scale;

FIG. 3 is a phantom lateral view of a spike or jaw of the invention in a greatly enlarged scale;

FIG. 4 is a top view of the spike or jaw as shown in Figure 3;

FIG. 5 is a rear view of the spike or jaw as shown in Figure 3;

FIG. 6 is an enlarged broken-away view of a spike or jaw in an operating position; FIG. 7 is a schematic broken-away view of a box-like rail mounted to the underside of a turntable of the tire-changing machine of Figure 1 ;

FIG. 8 is a schematic enlarged bottom view of means for simultaneous actuation of the spikes or jaws.

Detailed description of a preferred embodiment

Referring to the aforementioned figures, numeral 1 designates a tire- changing machine which comprises a base 2 with a column 3 vertically extending upwards therefrom.

The column 3 supports a connector 4 at its top end, for a horizontal operating arm 5 which extends in cantilever fashion and has an articulated joint 6 at its free end, for supporting a smaller column 7 that has a connector at its bottom end for a working tool.

A substantially horizontal surface 9 is defined on the base 2, with a motorized turntable 10, known as "self-centering turntable" 10, mounted thereto, upon which vehicle wheels (not shown) are designed to be supported and locked when mounting and removing tires to and from respective rims.

Four spikes 1 1 , also known as jaws, are mounted to the turntable 10 and simultaneously slide between two positions, namely an inactive position, in which they release the rims, and an active position in which they engage the edges of the rims and lock them to the turntable 10.

The four spikes 1 1 are actuated by special simultaneous actuation means, generally referenced 12 and described in greater detail below.

Namely, each of the four spikes 1 1 moves from the exterior of the turntable toward the center 10 and vice versa, by sliding along a slot 14 formed in and through the turntable 10.

The four slots 13 are in radial cross arrangement, as shown in Figures 1 and 2.

A box-like rail 14 is mounted level with each slot 13, by being connected to the underside 10B of the turntable 10, opposite to the top working surface

10A, such rail having a longitudinal top opening 15 and an opposite longitudinal lower opening 16, both longitudinally aligned to the respective slot 13 and parallel thereto.

Referring to Figures 3, 4, 5 each of the spikes 1 1 is shown to comprise a body 17 having a substantially transversely narrow and longitudinally elongate shape.

The body 17 forms a base 18 and an engagement tooth 19, which extends upwards and is designed, in the active position, to engage with an edge of a wheel rim, by fitting between the latter and the bead of the tire that is possibly mounted thereto, thereby fixing the rim to the turntable 10.

The base 18 extends at its bottom, i.e. opposite to the tooth 19, with a shoe 20, which is rigidly joined to the base 18 and to the body 17 and supports two pairs of freely rotating first wheels 21 , whose axes of rotation "R" are parallel to the base 18 and perpendicular to the longitudinal axis "Z" thereof.

These first wheels 21 are designed to slide while being guided within their respective rail 14, and to hold the base 18 slightly raised, typically by a few millimeters, from the working surface 10A of the turntable 10, such that no contact exists between the latter and the bottom face of the base 18, referenced 18A.

Referring now to Figures 3 and 4, the shoe 20 appears to be formed with a compartment 22, open at two sides, in which two successive, freely rotating second wheels 23 are accommodated, which have axes of rotation "Y" parallel to each other and perpendicular to the base 18.

These two second wheels 18 have such diameters as to allow their respective outer rolling surfaces to project out of the compartment 22, such that they may roll on the mutually facing inner edges of their respective slots 13, referenced 13A, while still guiding the bodies 17 as each spike slides between the two active and inactive positions.

A pin 24 extends from the bottom surface of the shoe 20, referenced 20A, in the downward direction i.e. opposite to the base 18, and has a freely- rotating third wheel keyed thereto, whose purpose is to couple with the simultaneous actuation means 12 for receiving motion therefrom, to drive each spike 1 1 .

Namely, each third wheel 25 is engaged in a slot-shaped cam profile 26 in a plate 27, which typically has a circular shape or a rounded perimeter, and is mounted under the turntable 10 and coaxial therewith, and may be actuated by a pair of actuators 28, typically of pneumatic type, or by other equivalent members known to the skilled person, which have their respective stems 29 hinged at their free ends to the plate 27 and have the cases 30 in which the respective pistons slide, fixed to the base 2 of the tire changing machine 1 .

Each cam profile (or slot) 26 has one end 26A oriented in the centripetal direction of the plate 27 and an opposite end 26B oriented in the centrifugal direction.

The position of the two actuators relative to the plate 27 is such that a couple of forces is created, which rotates it either clockwise or counterclockwise.

The self-centering device of the invention may have, if needed, raised lifting ribs or bars 31 arranged on the working surface 10A of the turntable 10, advantageously alternated to the slots 13 and radially directed like the latter.

These ribs or bars 31 may either be formed directly during fabrication of the turntable 10 and hence be stable, or be removably applied (or even simply laid) thereon at a later time to be used when needed.

The operation of the self-centering device is substantially similar to that of a known self-centering device of a prior art tire-changing machine, except that the spikes 1 1 slide between the two active and inactive positions with minimized friction between the respective bases 18 and the working surface 10A.

This advantageous effect is obtained by causing the first wheels 21 to slide in respective rails 14, such that the first wheels 21 slidingly contact the rails 14, instead of the bottom faces 18A of the bases 18 contacting the working surface 10A, which faces are conversely slightly raised.

The direction of the spikes 1 1 is maintained by the engagement between the second wheels 23 that slide on the inner faces 13A of the slots 13, which also generates minimized friction.

The simultaneous alternate actuation of the spikes 1 1 , into the two active and inactive positions is obtained by rotating the plate 27 in the two opposite counterclockwise or clockwise directions; these rotations transfer motion to the spikes 1 1 through the engagement between all the third wheels 25 and their respective cam profiles 26, i.e. the slots that define the cam profiles 26; here again the friction generated between the rolling surfaces of the third wheels 23 and the edges of the cam profiles 26 is minimized.

Furthermore, the use of ribs 31 affords optimized positioning of wheel rims relative to the working surface 10A, namely in a slightly raised position with respect to the latter, thereby avoiding damages to the rims caused by the spikes 1 1 when sliding toward or away from them, as well as damages caused by direct contact between the rims and the working surface 10A.

In fact, all the parts of the self-centering device of the invention have been found to individually generate low friction when moving, because their movements are obtained by freely rotating, i.e. idle, wheels, which generate very low friction forces between their rolling surfaces and the support and sliding surfaces, as compared with those generated by wiping contact.

The invention has been found to fulfill the intended objects.

The invention so conceived is susceptible to changes and variants within the inventive concept.

Also, all the details may be replaced by other technical equivalent elements.

In its practical implementation, any material, shape and size may be used as needed, without departure from the scope as defined by the following claims.