EP3707487A1

EP3707487A1 - A balancing machine having a blocking of vehicle wheels on the balancing shaft

Info

Publication number: EP3707487A1
Application number: EP18800775.1A
Authority: EP
Inventors: Gino Ferrari; Franco Maioli
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-11-10
Filing date: 2018-11-08
Publication date: 2020-09-16
Also published as: WO2019092768A1

Abstract

The balancing machine (1) with clamping of the wheels (2) of vehicles on the balancing shaft (3) comprises a frame (4), a balancing shaft (3) supported horizontally cantilevered and which has an axial cavity (5, 5A), an intermediate end (3 A) facing toward the frame and an opposite distal end (3B) facing toward the outside, between which a segment (S) of the balancing shaft is defined; a support flange (6) of a wheel to be balanced; clamping means (19) of the wheel against the flange which comprise at least a slot (8) made longitudinally in the distal end; a slider (9) mounted slidingly inside the axial cavity between an active position and an inactive position and that supports at least one pawl (10) mobile between an engagement position and a disengagement position; an elastic element (12) to thrust the slider into the engagement position; a clamping element (19) that can be slidingly fitted on the balancing shaft; and which has a toothing (21) made inside the cylindrical body in which the pawl (10) can be engaged.

Description

A BALANCING MACHINE HAVING A BLOCKING OF VEHICLE WHEELS ON THE BALANCING SHAFT DESCRIPTION

Field of the invention

The invention concerns a balancing machine with clamping of the wheels of vehicles on the balancing shaft, generally usable to clamp the wheels of vehicles quickly and in a rotational direction, making them temporarily integral with the balancing shaft until the balancing operations are completed, irrespective of the transverse sizes of the wheels.

Background of the invention

Numerous versions are known of devices for clamping the wheels of vehicles on the balancing shafts of balancing machines, used both to clamp the axial sliding of the wheels on the shafts, and also to make the wheels and the shafts temporarily integral with each other during rotation.

Typically, these devices are either manually driven or semi-automatic.

It is known that a machine for balancing wheels of vehicles typically consists of a base frame that supports cantilevered a rotating and horizontal balancing shaft, on which the wheels to be balanced are fitted and clamped.

To perform the balancing, the wheel to be balanced is loaded onto the balancing shaft, making the latter pass inside the central hole of the rim of the wheel and making it slide until it rests on a transverse flange that is attached on the end of the shaft facing toward the frame.

When the wheel is positioned completely in contact with the support flange, a clamping device is inserted on the balancing shaft which clamps it against the support flange for the time necessary to perform the balancing step and which is removed at the end of this step to free the wheel and remove it from the balancing shaft.

Typically, a manually driven clamping device comprises a sleeve body which, at one end to be faced toward the wheel, supports a conical tip that is inserted into the central hole of the rim, keeping it raised from the shaft, in a centered position with respect to the latter and keeping the wheel pressed against the support flange.

When the wheel is mounted and fixed on the balancing shaft, the latter is driven in rotation at high speed by means of a suitable motor unit, and a possible transmission connection which are normally housed inside the frame.

During rotation, the balancing machine detects wheel imbalances and the precise imbalance points which are then corrected by the operators by applying corrective weights to the specific points identified by the balancing machine.

After completing the balancing operations, the clamping device is deactivated and removed from the balancing shaft and the wheel is also removed from the balancing shaft to be reassembled on the vehicle.

For this type of clamping devices, a pawl coupling is typically provided between the balancing shaft and the sleeve body and a relative and micrometric movement between the latter and the conical tip for the precision insertion of the latter in the central hole of the wheel rim.

Another device to automatically clamp the wheels on the balancing shafts is known from the European patent EP0836086.

The device according to this patent comprises a rotating hollow shaft that at one end supports a flange to clamp a wheel cantilevered, a secondary shaft that can obtain a motion of translation inside the hollow shaft by means of preloaded springs in such a way as to keep the secondary shaft raised from the clamping flange, by clamping the wheel in this way.

The device also comprises a pneumatic cylinder to make the secondary shaft translate toward the clamping flange, so as to allow the release of the wheel and, at the same time, a further loading of the springs.

For machines of this type, the clamping device has at least two gas springs which are parallel to the secondary shaft and that are interposed between a pulley rigidly coupled to the hollow shaft and the free end of the secondary shaft.

A cylinder is also provided whose stem acts on the end of the secondary shaft which can preload the gas springs to allow the translation movement of the secondary shaft toward the clamping flange and, therefore, allow the release of the wheel.

Stops are also provided to stop the stroke of the secondary shaft and elastic elements to make the secondary shaft and the piston rod return into the initial position, allowing the gas springs to restore the clamping of the wheel.

The state of the art has some disadvantages. A first disadvantage related to manually operated clamping devices is that their positioning and their clamping force are conditioned by the manual skill and accuracy of the operator who, if distracted or not very skilled, risks compromising the correct positioning of the wheel on the balancing shaft and, consequently, making the balancing wrong and useless.

A second disadvantage related to the clamping device described in the prior art patent EP0836086 is that the whole group of components that drives the sliding of the secondary shaft inside the hollow balancing shaft rotates together with the latter due to the mechanical constraint provided between the components.

Therefore, during the rotation of the entire balancing unit, that is, the primary shaft, the secondary shaft, the pneumatic cylinder and the gas springs, imbalances occur that are derived specifically from these components and not just from the wheel to be balanced and that are added to those of the latter.

This circumstance creates an incorrect detection of the entity of the specific imbalances of the wheel and the consequent values of weights to be applied on this in order to obtain the necessary corrections and the right balance.

Therefore, due to the wrong detection, the operators correct the total imbalances detected by the balancing machine during the rotation step of the balancing shaft with on board the wheel to be balanced, but, after the wheel has been disassembled from the latter, it is still imbalanced, having been loaded with correction weights which have incorrect values, distorted by the imbalances caused by the group of rotating components of the balancing machine.

Another disadvantage concerning the device disclosed in the patent EPO0836086 is that the structure of the whole clamping unit is complicated, heavy and costly to make, due to the large number of components used.

This makes the balancing machines on which this device is mounted rather expensive, unreliable in results and complicated to maintain.

Presentation of the invention

One object of the invention is to obviate the disadvantages of the prior art, by providing a balancing machine with a clamping of the wheels of vehicles on the balancing shaft that allows to precisely detect only the real imbalances of a wheel to be balanced, without the imbalance values being influenced by additional imbalances derived from components of the clamping device. Another object of the invention is to provide a balancing machine with a clamping of the wheels of vehicles on the balancing shaft which has a simplified, robust and economical structure compared with known balancing machines.

According to one aspect of the invention, a balancing machine is provided with a clamping of the wheels of vehicles on the balancing shaft, according to the features of claim 1.

Other features of the invention are indicated in the dependent claims.

The invention allows to obtain the following advantages:

- to accurately determine the imbalance values related only to a wheel to be balanced, without errors occurring in the detection of imbalances due to the rotation motion of the dynamic components of the balancing machine and of its clamping unit;

- to obtain a balancing machine with a clamping of the wheels of vehicles on the balancing shaft that has a simplified structure and is therefore lighter and less expensive than known balancing machines.

Brief description of the drawings

Other characteristics and advantages of the invention will become more apparent from the detailed description of a preferred but not exclusive embodiment of a balancing machine with a clamping of the wheels of vehicles on the balancing shaft, shown by way of non-restrictive example in the attached tables of drawings in which:

FIG. 1 is a very schematic view of a balancing machine for balancing wheels of vehicles;

FIG. 2 is a view in enlarged scale of a portion of the balancing shaft of the machine in fig. 1 ;

FIG. 3 is a longitudinal section view of the shaft portion in fig. 2, taken along a plane III-III;

FIG. 4 is a schematic sectional view of one portion of fig. 3;

FIG. 5 is a schematic sectional view and on a further enlarged scale of the portion in fig. 4;

FIG. 6 is a longitudinal section view of the shaft portion in fig. 2 on which a wheel to be balanced has been inserted.

Detailed description of a preferred example embodiment With reference to the above figures, a balancing machine with a clamping of wheels 2 of vehicles on the balancing shaft 3 is indicated in its entirety by the reference number 1.

The balancing machine 1 , hereinafter briefly machine 1 , typically comprises a base frame 4 which supports the balancing shaft 3 in a horizontal and cantilevered position.

The shaft 3 has a longitudinal axis "A" and an axial cavity 5 and defines an intermediate end 3A which faces toward the frame 4 and an opposite distal end 3B that faces toward the outside between which is defined a segment "S" of the balancing shaft which is intended to be inserted into the central hole of a rim of a wheel 2 to be balanced.

A support flange 6 is attached on the intermediate end 3A against which a wheel 2 to be clamped is intended to rest.

The flange 6 consists of a cylindrical body 7 that defines on one end a circular crown 7A which has a bigger diameter than the diameter of the cylindrical body 7 and which, therefore, protrudes peripherally from it, defining a flat and circular surface 7B to support the wheel 2.

To clamp the wheel 2 against the flange 6 clamping means are typically provided that, in the version visible in the drawings, comprise a pair of slots 8 which are made longitudinally in the distal end 3B of the balancing shaft 3, but in diametrically opposite positions from each other, as can be seen in figs. 4 and 5.

The clamping means also comprise a cylindrical slider 9 which is mounted sliding inside the axial cavity 5 and can be moved between an active position and an inactive position, as will be explained in more detail later.

The slider 9 supports at least one pair of pawls 10, mobile between an engagement position in which they diverge from each other and protrude from the respective slots 8, and a disengagement position in which they converge toward one another and are both retracted from the respective slots 8.

In detail, with reference to the drawings, it can be seen that the pawls 10 are co-hinged bilaterally to the slider 9 with a pin 10A and can rotate around it according to arc-type trajectories, both diverging from each other toward the outside, and also converging toward the inside of the axial cavity 5.

Inside the latter, precisely in correspondence with the distal end 3B, an elastic thrust element 11 is mounted, which closes the axial cavity 5 and which is suitable to keep the contact constant with a corresponding end 9A of the slider 9 and to keep it normally thrust into its active position in which the two pawls 10 protrude from the respective slots 8.

The elastic element is loaded by compression when the slider 9 moves with an inactive sliding, in the direction opposite to the frame 4.

This inactive sliding causes the two slots 10 to return from the respective slots 8, since the two pawls 10 hit the corresponding end edges of the slots 8 and the latter press them, making them progressively rotate one toward the other toward the inside of the axial cavity 5.

The elastic element 11 can be made in different ways: in the version shown in the drawings, the elastic element 1 1 is made in the form of a pre-loaded cylinder 12 with the stem 12A protruding from the sleeve to maintain contact with the end 9A.

The cylinder 12 is retained inside the axial cavity 5 in correspondence with the end 3B, for example by means of a screw cap 13.

In an alternative embodiment of the elastic means 1 1, the pre-loaded cylinder 12 can be replaced, for example, by a helical spring (not shown because it is known to the person of skill in the art) loadable by compression, which is housed and held inside the axial cavity 5 in correspondence with the distal end 3B.

With reference to fig. 4, it can be seen that, when the slider 9 is in the active stroke condition, the two pawls 10 are held elastically and normally in a separated position from each other by a helical spring 14 which is interposed between them and which has its ends contained in hollow seatings 15 made opposite each other for this purpose in each of the pawls 10: as we said, in this condition, both the pawls 10 protrude from the respective slots 8.

The slider 9 is driven in axial movement by a drive stem 16 which passes coaxially and in a sliding manner through the whole balancing shaft 3, sliding in an extension 5A of the axial cavity 5 which has a slightly reduced diameter with respect to the diameter of the latter.

As can be seen in figs. 3-5, the drive stem 16 has an end 16A which is screwed into a threaded hollow seating 9B made in the slider 9 on the opposite side to the end 9A of the latter, while the opposite end 16B protrudes for a segment from the extension 5 A of the axial cavity 5 and faces coaxially toward the stem 17 of a pneumatic drive cylinder 18 which is attached inside the frame 4, for example with a flange 4 A.

Therefore, the drive stem 16 is rigidly attached to the slider 9 and transmits its movements to the latter.

As can be seen in the drawings, particularly in figs. 2 and 3, the end 16B is not rigidly connected to the stem 17, but receives from it, in a specific functioning condition, only an action of axial thrust, as will be described below.

A clamping element 19 of a wheel 2 against the support flange 6 is intended to be fitted on the segment "S".

In detail, the clamping element consists of a cylindrical body 19 that can be fitted accurately and slidably on the segment "S" of the balancing shaft 3 and a hub 20 to contact with a wheel 2 and to thrust it, which is associated with an end 19A of the cylindrical body 19 facing the frame 4.

Inside the cylindrical body 19 there is a toothing 21 with oriented teeth in which both the pawls 10 can be engaged when the slider 9 is in the active condition.

It must be underlined that, even if in the preferred embodiment of the invention there are two pawls 10 and two slots 8, the person of skill understands that it is also possible to provide to use a single pawl 10 and a corresponding single slot 8 that it can pass through or from which it can retract; in the same way it could also be provided to use three pawls 10 disposed radially on the slider 9, for example at angles of 120°, and a corresponding three slots 8 made in the "S".

The machine works as follows: a wheel 2 to be balanced is inserted on the balancing shaft 3 of the balancing machine 1 until it rests against the flat surface 7B of the cylindrical body 7.

Precisely, in the insertion of the wheel 2, the shaft 3 passes through the central hole which is typically present in the rim of the wheel 2.

In the insertion step, the pneumatic cylinder 18 is activated so that its stem 17 is in contact with the end 16B of the drive stem 16 and makes it slide inside the extension 5 A of the axial cavity 5.

This sliding also moves the slider 9 toward the cylinder 12, thrusting on the stem 12A of the latter, making it retract and loading it by compression. The movement of the slider 9 automatically determines the convergent retraction of both pawls 10 from the respective slots 8, due to the contact of both against the edges of the slots 8, and the consequent compression of the helical spring 14.

When the wheel 2 is completely inserted on the shaft 3, the pneumatic drive cylinder 18 is deactivated, the stem 17 retracts and the force of the opposite cylinder 12 previously loaded by compression makes the drive stem 16 move in the opposite direction to the previous one, that is, in the direction of the stem 17, but without coming into contact with it.

The displacement of the drive stem 16 also moves the slider 9 in the opposite direction to the previous one and both the pawls 10 vertically realign themselves to the respective slots 8 and are able to again separate from each other with the action of the helical spring 14 and therefore protrude through them, as can be seen in figs. 4 and 5.

It must be pointed out that in this configuration both pawls 10, although they protrude from the respective slots 8, remain elastically compressible toward each other.

The operator, in order to clamp the wheel 2 against the flange 6, more precisely against the surface 7B of the circular crown 7A, fits the clamping element 19 onto the shaft 3, making it slide over it.

When the cylindrical body 19, as it slides, meets the protruding pawls 10, it presses them elastically and forces them to retract into the slots 8, but maintains a thrust force toward the outside.

In this way, the oriented teeth of the toothing 21 , during the sliding of the clamping element 19, automatically engage slidingly with both pawls 10 which are kept thrust elastically toward them, engaging mono-directionally in the cavities defined in succession between the teeth.

By the expression mono-directionally, we mean a direction that prevents the accidental detachment of the clamping element 19 from the balancing shaft 3.

The operator continues the insertion of the clamping element 19 until the hub 20 comes into contact with the wheel 2, pressing it and clamping it against the flange 6.

In this way, the balancing machine 1 is ready to start the balancing step according to the known procedure.

It should be noted that the rotation of the balancing shaft 3, activated to search for and determine the imbalances of the wheel 2, does not draw with it the pneumatic cylinder 18 for the reason that these two elements are completely disconnected during the balancing step.

This is due to the fact that the cylinder 18 is supported fixed to the inside of the frame 4 of the balancing machine 1 , while the balancing shaft 3 supported rotating by the latter, but with the end 16B of the drive stem 16 distanced from the stem 17 of the pneumatic cylinder 18 sufficiently to avoid contact: in this way, the cylinder 18, being static, can in no way influence the balancing action during the rotation of the balancing shaft 3.

When the balancing machine 1 has completed the balancing of the wheel 2, to remove it from the shaft 3 the operator again drives the pneumatic cylinder 18 which in this step again thrusts its own stem 17 into contact with the end 16B of the drive stem 16, making it slide again together with the slider 9 in the opposite direction toward the other cylinder 12 which can be loaded by compression.

The two pawls 10, due to the sliding of the slider 9, are again pressed into the retracted position by the respective slots 8 toward the inside and the operator can then remove first the clamping device 19 and immediately thereafter also the wheel 2.

The balancing machine 1 therefore remains in configuration ready to receive another wheel 2 to be balanced which will be clamped on the balancing shaft as previously described.

In practice it has been found that the invention achieves the predefined purposes.

Modifications and variants can be made to the invention as conceived, all of which come within the concept of the invention.

Moreover, all the details can be replaced with other technically equivalent elements.

In the practical embodiment, the materials used as well as the shapes and the sizes can vary according to requirements, without for this reason leaving the field of protection of the following claims.

Claims

1. A balancing machine (1) with clamping of the wheels (2) of vehicles on the balancing shaft (3), said machine comprising:

- a base frame (4);

- a balancing shaft (3) supported horizontally cantilevered by the frame (4), which has a longitudinal axis (A) and an axial cavity (5, 5 A), an intermediate end (3 A) facing toward said frame (4) and an opposite distal end (3B) facing toward the outside, between which a segment (S) of the balancing shaft (3) is defined on which a wheel (2) to be balanced can be positioned;

- a support flange (6) of a wheel (2) to be balanced, attached on said balancing shaft (3);

- clamping means of said wheel against said support flange (6);

characterized in that said clamping means comprise:

- at least a slot (8) made longitudinally in said balancing shaft (3);

- a slider (9) mounted slidingly inside the axial cavity (5, 5 A) between an active position and an inactive position and that supports at least one pawl (10) mobile between an engagement position in which it protrudes from the slot (8) and a disengagement position in which it is retracted from the slot (8);

- an elastic element (12) to thrust said slider (9) into said active position and able to be loaded by compression;

- a clamping element of a wheel (2) against said support flange (6), said clamping element having:

- a cylindrical body (19) which can be fitted slidingly on the balancing shaft (3);

- a hub (20) to contact with a wheel (2) and thrust it, which is associated with one end (19A) of said cylindrical body (19) facing toward said frame (4); and

- a toothing (21) made inside the cylindrical body (19) in which said pawl (10) can be engaged in said engagement position.

2. Balancing machine as in claim 1, wherein said toothing (21) comprises a succession of teeth oriented in one direction, intended to hold said pawl (10) in said engagement position.

3. Balancing machine as in claim 1, wherein said at least one slot (8) is made in said distal end (3B).

4. Balancing machine as in claim 1, wherein said elastic thrust element (12) is chosen alternatively from either a cylinder or a spring, both able to be loaded by compression

5. Balancing machine as in claim 1, wherein a drive stem (16) that has one end (16A) connected to said slider (9) and the opposite end (16B) protruding from said balancing shaft (3) is housed sliding in said axial cavity (5, 5A).

6. Balancing machine as in any claim hereinbefore, wherein said balancing machine (1) comprises drive means (18) to drive the sliding of said drive stem (16).

7. Balancing machine as in claim 6, wherein said drive means comprise a pneumatic actuator (18) that has its own stem (17) coaxially aligned to said opposite end (16B) protruding and alternately mobile between a thrust position in contact with said opposite end (16B) and a retracted position disconnected from said opposite end (16B).