WO2014097106A1

WO2014097106A1 - Balancing machine for the balancing of vehicle wheels

Info

Publication number: WO2014097106A1
Application number: PCT/IB2013/060971
Authority: WO
Inventors: Luciano Gabioli
Original assignee: Sicam S.R.L.
Priority date: 2012-12-21
Filing date: 2013-12-16
Publication date: 2014-06-26
Also published as: ITMO20120324A1

Abstract

The balancing machine (1) for the balancing of vehicle wheels comprises: - a base frame (2); a balancing shaft (3) substantially horizontal on which can be fixed a vehicle wheel (R) to be balanced; a rotoidal resting unit (6, 7, 8) supporting the balancing shaft (3) in a rotatable way around its own axis; - motor means (9) for placing in rotation the balancing shaft (3) around its own axis; a bending-torsional structure (12, 13, 14) having a first plate (12), a second plate (13) and a third plate (14) arranged in a U-shape, wherein the first plate (12) is associated with the base frame (2) and connects the second plate (13) to the third plate (14) and wherein the second plate (13) and the third plate (14) support substantially opposite sides.of the rotoidal resting unit (6, 7, 8) and are subject to a bending-torsional condition due to the effect of the unbalance of the wheel (R) in rotation on the balancing shaft (3); - sensor means (20, 21) associated with at least one between the second plate (13) and the third plate (14) and suitable for detecting the bending-torsional condition; and a processing and control unit (22) operatively associated with the sensor means (20, 21) and suitable for determining the unbalance of the wheel (R) starting from the bending-torsional condition.

Description

BALANCING MACHINE FOR THE BALANCING OF VEHICLE WHEELS

Technical Field

The present invention relates to a balancing machine for balancing vehicle wheels.

Background Art

It is known that the wheels of vehicles are generally made up of a cylindrical metal rim having, at the axial extremities, annular flanges between which is defined a channel for the interlocking fitting of an elastic tyre, the side portions of which, so-called "beads", are stopped up fast on the annular flanges themselves.

Also known is the need to perform frequent balancing operations which consist in fitting specific balancing weights, made of lead or other material, in correspondence to predetermined points of the wheel and along the rim and the need to check the wheel's inclination to roll correctly following a geometric test of the rim and the tyre.

The fitting of the balancing weights does in fact offset, during wheel rotation, the presence of any tyre and/or rim irregularities which would lead to vibrations or stresses during vehicle movement.

To perform such operations, balancing machines are commonly used comprising a base frame supporting a horizontal shaft, so-called "balancing shaft", which is axially rotatable due to the action of motor means and on which the wheel rim is keyed by means of suitable engagement and centring parts. The amount of wheel unbalance is determined during the rotation by suitable electronic or electromechanical devices, such as force transducers applied along the balancing shaft.

Once the necessary measurements have been made, the machine is suitable for calculating the size and the position of the balancing weights to be fitted on the wheel rim to offset the irregularities of the wheel.

The fitting of the balancing weights is usually performed manually by an operator in one or more precise points of the wheel rim indicated by the machine. Figure 1 shows an example of a balancing machine of traditional type, wherein the balancing shaft A exits overhanging from the frame B of the machine and supports the wheel C.

The balancing shaft A rests on a pair of rotoidal bearings D, in correspondence to which are fitted the force transducers, of which an outer transducer Ee closer to the wheel C and an inner transducer Ei further away from the wheel C.

Any unbalancing force F acting on the wheel C changes into a pair of forces Fe,

Fi acting on the rotoidal bearings and detected by the transducers Ee, Ei, which provide at output a pair of electronic signals separate from one another.

The quality pattern of the electronic signals S (deemed as the absolute value of the forces Fe, Fi) dependent on the overhang, i.e., on the distance of the unbalancing force F with respect to the transducers Ee, Ei, is shown in figure 2, where by Se has been indicated the pattern for the outer transducer Ee and by Si has been indicated the pattern for the inner transducer Ei.

Due to the substantial independence of the two rests, the patterns Se and Si consist of two substantially parallel and monotone straight lines growing with the overhang, which cancel out one another (points Ze and Zi) in correspondence to the rests themselves; in particular, the pattern Se cancels itself out in correspondence to the inner transducer Ei while the pattern Si cancels itself out in correspondence to the outer transducer Ee.

The balancing machine having the classic configuration shown in figures 1 and

2 have, however, several drawbacks.

In this respect, it is underlined that, with reference to the example shown in figure 1, the quantity of the unbalancing force F is obtained by the difference of the absolute values of the forces Fe, Fi measured by the transducers Ee, Ei, i.e., by the vertical distance between the straight lines Se and Si.

This means that any percentage error that might affect each transducer Be, Ei for the measurement of the forces Fe, Fi has an even more significant effect on their difference, thus favouring the propagation of the percentage errors.

To this must be added that, percentage error being equal, the absolute errors of the transducers Ee, Ei vary linearly with the axial distance of the wheel C with respect to the outer transducer Ee (distance d in figures 1 and 2), growing with the overhang; in the machine work area, i.e., the area x of figure 2 wherein the wheel C and the unbalancing force F are actually to be found, the axial errors may not be negligible.

It should also not be forgotten that to reduce the propagation of the percentage errors in a balancing machine haying the classic configuration shown in figures 1 and 2, the rotoidal bearings D and relative transducers Ee, Ei must be placed at a reciprocal very great distance (distance b in the figures 1 and 2) if compared with the distance d of the wheel, but this inconveniently involves far from negligible total machine overall dimensions.

To at least in part overcome these drawbacks, the document US 6,430,992 proposes a balancing machine having a particular overhanging support system for the balancing shaft which consists in a series of specifically arranged levers and hinges.

Such support system permits considering the balancing shaft resting virtual on two points positioned to the right and the left of the wheel, i.e., in a virtual configuration wherein the balancing shaft in not supported overhanging but rather at the centre of two supports.

The structural configuration envisaged in US 6,430,992, nevertheless, is very complicated and not practical and easy to achieve, making both the assembly of the machine and any maintenance jobs particularly difficult.

Description of the Invention

The main object of the present invention is to provide a balancing machine for the balancing of vehicle wheels which is suitable for operating with greater precision and less errors compared to the traditional machines shown in the example of figures 1 and 2 and which, at the same time, is particularly simple from a construction and functional viewpoint.

Another object of the present invention is to provide a balancing machine for the balancing of vehicle wheels which allows overcoming the mentioned drawbacks of the state of the art within the ambit of a simple, rational, easy, effective to use and low cost solution.

The above objects are achieved by the present balancing machine for the balancing of vehicle wheels, comprising: at least a base frame;

at least a balancmg shaft substantially horizontal on which can be fixed a vehicle wheel to be balanced;

at least a rotoidal resting unit supporting said balancing shaft in a rotatable way around its own axis; and

motor means for placing in rotation said balancing shaft around its own axis;

characterized by the fact that it comprises:

at least a bending-torsional structure having a first plate, a second plate and a third plate arranged in a U- shape, wherein said first plate is associated with said base frame and connects said second plate to said third plate and wherein said second plate and said third plate support substantially opposite sides of said rotoidal resting unit and are subject to a bending-torsional condition due to the effect of the unbalance of said wheel in rotation on said balancing shaft;

sensor means associated with at least one between said second plate and said third plate and suitable for detecting said bending-torsional condition; and

at least one processing and control unit operatively associated with said sensor means and suitable for determining the unbalance of said wheel starting from said bending-torsional condition.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more evident from the description of a preferred, but not sole, embodiment of a balancing machine for the balancing of vehicle wheels, illustrated purely as an example but not limited to the annexed drawings in which:

figure 1 is a schematic and partial section view of a traditional balancing machine;

figure 2 is a schematic graph illustrating the patterns of the electronic signals detected by the machine in figure 1 ;

figure 3 is an axonometric view of the machine according to the invention;

figure 4 is an exploded view of a detail of the machine according to the invention;

figure 5 is an axonometric view of the detail of the machine in figure 4;

figure 6 is an axial section view of the detail of the machine in figure 4;

figure 7 is a view from above of the detail of the machine in figure 4;

figure 8 is a front view of the detail of the machine in figure 4;

figure 9 is a schematic graph illustrating the patterns of the electronic signals detected by the machine according to the invention.

Embodiments of the Invention

With particular reference tp such figures, globally indicated by 1 is a balancing machine for the balancing of vehicle wheels.

The machine 1 comprises a base frame 2 for resting on the ground, on which is mounted a substantially horizontal balancing shaft 3 for balancing a wheel R of vehicles to be balanced.

The base frame 2 comprises a main block 4 having a side panel 4a from which the balancing shaft 3 extends overhanging horizontally.

The wheel R comprises an inner rim on which is mounted an outer tyre.

The wheel R can be fitted on the balancing shaft 3 in a substantially coaxial way to the central rolling axis thereof.

For this purpose, the balancing shaft 3 bears a grip unit 5 which permits withholding the centre of the wheel R.

The balancing shaft 3 is supported in a rotatable way around its axis thanks to a rotoidal resting unit 6, 7, 8.

The rotoidal resting unit 6, 7, 8 comprises at least a tubular body 6 which extends horizontally and inside which is fitted at least a portion of the balancing shaft 3.

The tubular body 6 has a square- section conformation and has two circular elements 6a in correspondence to its open extremities.

The rotoidal resting unit 6, 7, 8 also comprises a proximal rotoidal bearing 7 and a distal rotoidal bearing 8; in this respect it is pointed out that, in the present treatise, the adjectives "distal" and "proximal" are used with reference to the position of the wheel R mounted on the balancing shaft 3, and consequently the proximal rotoidal bearing 7 is the outermost one, closest to the wheel R, while the distal rotoidal bearing 8 is the innermost one, furthest from the wheel R. The rotoidal bearings 7, 8 are housed inside the tubular body 6 and, more specifically, inside the circular elements 6a.

According to the position of the rotoidal bearings 7, 8, the balancing shaft 3 can be split up into a resting portion 3 a, extending substantially between the rotoidal bearings 7, 8, and a first overhanging portion 3b, extending overhanging from the proximal rotoidal bearing 7 and in correspondence to which the wheel R can be fixed.

In the particular embodiment shown in the illustrations, furthermore, the balancing shaft 3 also comprises a second overhanging portion 3 c, extending overhanging from the distal rotoidal bearing 8 and with which motor means 9 are associated for placing the balancing shaft 3 in rotation around its own axis. The motor means 9, e.g., comprise a pulley 10 keyed on the second overhanging portion 3 c on which a flexible element 11 is at least partially wrapped, closed on itself in a loop, such as a belt, a band, a chain or the like.

The flexible element 11 transmits the movement of a motor, not shown in the illustrations, and drives the pulley 10 and the balancing shaft 3 in rotation.

Alternative embodiments cannot however be ruled out wherein the motor means 9 are of different type to those shown in the illustrations such as, e.g., in the case of their consisting of a motor mounted directly on the tubular body 6 and/or coaxial to the balancing shaft 3.

The rotoidal resting unit 6, 7, 8 is mounted on the base frame 2 inside the main block 4 by interposition of a bending-torsional structure 12, 13, 14, i.e., a structure with at least a part suitable for twisting or bending by effect of the rotation of the wheel R on the balancing shaft 3.

More in detail, inside the block 4 the base frame 2 comprises a small base 15 which is substantially horizontal and which, unlike the bending-torsional structure 12, 13, 14, is considered to all effects rigid and non-deformable.

On the small base 15 is mounted the bending-torsional structure 12, 13, 14, which is equipped with a first plate 12, a second plate 13 and a third plate arranged in a U-shape.

The first plate 12 defines the base of the U and links together the second plate 13 and the third plate 14, which instead define the sides of the U.

The plates 12, 13, 14 are all arranged substantially parallel to the rotation axis of the balancing shaft 3.

In particular, the first plate 12 is arranged substantially horizontal and is steadily associated with the upper surface of the small base 15, e.g. by means of screws, bolts or the like 16.

Starting from the first plate 12, the second plate 13 and the third plate 14 extend and are arranged substantially symmetrical with respect to the vertical plane 17 on which lies the rotation axis of the balancing shaft 3.

More precisely, the second plate 13 and the third plate 14 extend substantially vertical.

To this must be added that the first plate 12 is arranged below the balancing shaft 3, with the second plate 13 and the third plate 14 which extend upwards from the first plate 12.

Alternative embodiments cannot however be ruled out wherein the bending- torsional structure 12, 13, 14 is arranged differently, e.g., with the first plate 12 vertical and the second and third plates 13, 14 horizontal.

The second plate 13 and the third plate 14 support substantially opposite sides of the rotoidal resting unit 6, 7, 8 and are subject to a bending-torsional condition by effect of the unbalance of the wheel R in rotation on the balancing shaft 3.

In this respect, it is underlined that within the scope of this treatise, the "bending-torsional condition" is defined as a situation wherein the second plate 13 and the third plate 14 are deformed by torsion and/or bending following the mechanical loading of the bending-torsional structure 12, 13, 14 deriving from the unbalance of the wheel R in rotation on the balancing shaft 3.

The second plate 13 and the third plate 14 are associated at the outside of the - tubular body 6.

For this purpose it is pointed out that due to its squared section shape, the tubular body 6 has two outer surfaces 18 substantially flat and opposite to each other, in correspondence to which are associated the second plate 13 and the third plate 14, e.g. by means of screws, bolts or the like 19. Alternative solutions cannot however be ruled out wherein the tubular body 6 is shaped differently, as e.g. in the case of its having a substantially circular section with flattened outer surfaces in correspondence to the second plate 13 and the third plate 14.

With at least one between the second plate 13 and the third plate 14 are associated sensor means 20, 21 which are suitable for detecting their bending- torsional condition and which are operatively associated with a processing and control unit 22 suitable for determining the unbalance of the wheel R starting from the above-mentioned bending-torsional condition of the second and third plates 13, 14.

In the embodiment shown in the illustrations, the sensor means 20, 21 are only associated with the second plate 13, but alternative embodiments cannot be ruled out wherein, instead, they are only associated with the third plate 14 or on both.

The sensor means 20, 21 comprise a first sensor element 20 and a second sensor element 21.

The sensor elements 20, 21 are selected from the list comprising: force transducers, load cells, piezoelectric sensors, piezoresistive sensors, extensometers.

Preferably the sensor elements 20, 21 are load cells placed between the second plate 13 and the base frame 2.

For this purpose, it is underlined that the base frame 2 comprises a rigid wall 23 which rises from the small base 15 opposite the second plate 13.

From the rigid wall 23 extend two horizontal screws 24 towards the second plate 13.

Between the horizontal screws 24 and the second plate 13 the load cells 20, 21 are interlocked which detect the bending-torsional movements of the second plate 13.

By specifically studying the point of application of the sensor elements 20, 21 on the second plate 13, the results can be obtained which will be better described below.

First of all, it must be underlined that at least one between the first sensor element 20 and the second sensor element 21 is associated with the second plate 13 substantially in correspondence to the horizontal plane 25 on which lies the rotation axis of the balancing shaft 3.

hi the embodiment shown in the illustrations, both the first sensor element 20 and the second sensor element 21 are fitted on the second plate 13 in correspondence to the above-mentioned horizontal plane 25 and are slightly spaced along the axial direction of the balancing shaft 3.

Having said as much, as median vertical plane 26 of the second plate 13 is defined the vertical plane orthogonal to the rotation axis of the balancing shaft 3 which passes through the centre of the second plate 13 (figures 6 and 7).

With respect to the median vertical plane 26, the second plate 13 is split up into a proximal half 27 and into a distal half 28, wherein the proximal half 27 is the outermost one and closest to the wheel , while the distal half 28 is the innermost one and furthest from the wheel R.

The portion of the second plate 13 intersected by the median vertical plane 26 must be deemed as being part of both the proximal half 27 and of the distal half 2_.8.

At least one between the first sensor element 20 and the second sensor element 21 are associated with the second plate 13 in correspondence to the distal half 28.

In the embodiment shown in the illustrations, both the first sensor element 20 and the second sensor element 21 are associated with the distal half 28.

More in detail, the first sensor element 20 is associated with the, distal half 28 substantially in the proximity of the median vertical plane 26 and, if necessary, in correspondence to it.

The second sensor element 21, instead, is slightly spaced along the axial direction of the balancing shaft 3 with respect to the first sensor element 20. The particular conformation of the bending-torsional structure 12, 13, 14 and the use of the above-mentioned sensor elements 20, 21 permit making a system which detects the unbalance of the wheel R in a better way than traditional machines.

In this respect, it is underlined that in figure 9 is shown the quality pattern of the electronic signals provided by the sensor elements 20, 21 depending on the overhang of the unbalancing force with respect to the bending-torsional structure 12, 13, 14, where by SI has been indicated the pattern for the first sensor element 20 and by S2 has been indicated the pattern for the second sensor element 21.

The pattern SI substantially consists of a monotone straight line increasing with the overhang, which cancels itself in a point Zl which, with respect to the work area y of the wheel R, i.e., the position where the wheel R is really fitted and where the unbalancing forces apply, is located on the side of the bending- torsional structure 12, 13, 14.

The pattern S2, instead, substantially consists of a monotone straight line decreash g with the overhang, which cancels itself in a point Z2 which, with respect to the work area Y of the wheel R, is located on the opposite side of the bending-torsional structure 12, 13, 14.

From the graph in figure 9, when compared to that of figure 2, it appears evident that the work area Y of the machine is arranged between the two signal cancellation points Z 1 , Z2.

This result is very important because, during the unbalance measuring and calculation operations, it determines a considerable reduction in error propagation compared to machines of traditional type having a graph of the type shown in figure 2.

It should not be forgotten, furthermore, that this result is obtained thanks to two sensor elements 20, 21 which do not need to be arranged at any great reciprocal distance, the entire supporting unit of the balancing shaft 3 being altogether very compact and of reduced dimensions.

Claims

1) Balancing machine (1) for the balancing of vehicle wheels, comprising: at least a base frame (2);

at least a balancing shaft (3) substantially horizontal on which can be fixed a vehicle wheel (R) to be balanced;

- at least a rotoidal resting unit (6, 7, 8) supporting said balancing shaft (3) in a rotatable way around its own axis; and

motor means (9) for placing in rotation said balancing shaft (3) around its own axis;

characterized by the fact that it comprises:

at least a bending-torsional structure (12, 13, 14) having a first plate (12), a second plate (13) and a third plate (14) arranged in a U-shape, wherein said first plate (12) is associated with said base frame (2) and connects said second plate (13) to said third plate (14) and wherein said second plate (13) and said third plate (14) support substantially opposite sides of said rotoidal resting unit (6, 7, 8) and are subject to a bending-torsional condition due to the effect of the unbalance of said wheel (R) in rotation on said balancing shaft (3);

sensor means (20, 21) associated with at least one between said second plate (13) and said third plate (14) and suitable for detecting said bending- torsional condition; and

at least one processing and control unit (22) operatively associated with said sensor means (20, 21) and suitable for determining the unbalance of said wheel (R) starting from said bending-torsional condition.

2) Machine (1) according to the claim 1, characterized by the fact that said first plate (12) is arranged substantially horizontal.

3) Machine (1) according to one or more of the preceding claims, characterized by the fact that said second plate (13) and said third plate (14) are arranged substantially symmetrical with respect to the vertical plane (17) on which lies the rotation axis of said balancing shaft (3).

4) Machine (1) according to one or more of the preceding claims, characterized by the fact that said second plate (13) and said third plate (14) are arranged substantially vertical.

5) Machine (1) according to one or more of the preceding claims, characterized by the fact that said first plate (12) is arranged below said balancing shaft (3), with said second plate (13) and said third plate (14) which extend upwards from said first plate (12).

6) Machine (1) according to one or more of the preceding claims, characterized by the fact that said rotoidal resting unit (6, 7, 8) comprises at least one proximal rotoidal bearing (7) and one distal rotoidal bearing (8), said balancing shaft (3) comprising a resting portion (3a), which substantially extends between said rotoidal bearings (7, 8), and a first overhanging portion (3b), which extends overhanging from said proximal rotoidal bearing (7) and on which said wheel ( ) is fixable.

7) Machine (1) according to the claim 6, characterized by the fact that said balancing shaft (3) comprises a second overhanging portion (3c), which extends overhanging from said distal rotoidal bearing (8) and with which said motor means (9) are associated.

8) Machine (1) according to the claim 6 or 7, characterized by the fact that said rotoidal resting unit (6, 7, 8) comprises at least a tubular body (6) inside which are housed said rotoidal bearings (7, 8) and outside which are associated said second plate (13) and said third plate (14).

9) Machine (1) according to the claim 8, characterized by the fact that said tubular body (6) has two outer surfaces (18) substantially flat and opposite to each other, in correspondence to which are associated with said second plate (13) and said third plate (14).

10) Machine (1) according to one or more of the preceding claims, characterized by the fact that said sensor means (20, 21) comprise a first sensor element (20) and a second sensor element (21) associated with said second plate (13).

11) Machine (1) according to the claim 10, characterized by the fact that said sensor elements (20, 21) are selected from the list comprising: force transducers, load cells, piezoelectric sensors, piezoresistive sensors, extensometers.

12) Machine (1) according to the claim 10 or 11, characterized by the fact that said, sensor elements (20, 21) are load cells placed between said second plate (13) and said base frame (2).

13) Machine (1) according to one or more of the claims from 10 to 12, characterized by the fact that at least one between said first sensor element (20) and said second sensor element (21) is associated with said second plate (13) substantially in correspondence to the horizontal plane (25) on which lies the rotation axis of said balancing shaft (3).

14) Machine (1) according to the claim 13, characterized by the fact that both said first sensor element (20) and said second sensor element (21) are associated with said second plate (13) substantially in correspondence to the horizontal plane (25) on which lies the rotation axis of said balancing shaft (3).

1 ) Machine (1) according to one or more of the claims from 10 to 14, characterized by the fact that said second plate (13) is split up into a proximal half (27) and into a distal half (28) with respect to a median vertical plane (26) substantially at right angles to the rotation axis of said balancing shaft (3), at least one between said first sensor element (20) and said second sensor element (21) being associated with said distal half (28).

16) Machine (1) according to the claim 1 , characterized by the fact that both said first sensor element (20) and said second sensor element (21) are associated with said distal half (28).

17) Machine (1) according to the claim 15 or 16, characterized by the fact that said first sensor element (20) is associated with said distal half (28) substantially in proximity of said median vertical plane (26).

18) Machine (1) according to the claim 17, characterized by the fact that said second sensor element (21) is associated with said distal half (28) substantially spaced along an axial direction from said first sensor element (20).