Balancing machine and method for balancing vehicle wheels

Abstract

A vehicle wheel balancing machine having a rotating shaft which supports a vehicle wheel, a means for supporting the rotating shaft, and force sensor means adapted to detect the imbalance forces generated during the rotation of the rotating shaft; an accelerator means accelerates the shaft and the wheel and an angular sensor means senses an angular position; an electronic means processes information obtained by the force sensor means and determines the value and the position of correction masses adapted to compensate an imbalance present on the wheel; a moving indicator means is moved by a motorized actuator means and is configured to project a light dot on the wheel; a fixed indicator means projects a luminous beam, perpendicular to the axis of rotation, or a luminous dot, having a fixed and known angle of incidence on the inner surface of the wheel; a coincidence of the moving luminous point with the fixed luminous line or dot identifies a desired position of a counterweight on the diameter of the wheel.

Claims

1. A vehicle wheel balancing machine, comprising a rotating shaft which supports a vehicle wheel, a means for supporting said rotating shaft, and force sensor means adapted to detect the imbalance forces generated during the rotation of said rotating shaft; said machine further comprising accelerator means adapted to accelerate said shaft and said wheel and angular sensor means for sensing an angular position; said machine further comprising an electronic means adapted to process information obtained by said force sensor means which determines the value and the position of correction masses adapted to compensate an imbalance present on said wheel; said machine further comprising at least one fixed indicator means and at least one moving indicator means; said at least one moving indicator means being moved by a motorized actuator means and being configured to project a light dot on said wheel; said at least one fixed indicator means being configured to project a luminous beam or a luminous dot, said at least one fixed indicator means having a fixed and known angle of incidence on the inner surface of said wheel, wherein said moving indicator means is configured to position said light dot such that said light dot is coincident with said luminous beam or said luminous dot, the coincidence of said light dot with said luminous beam or said luminous dot identifying the diameter of said wheel, and wherein said moving indicator means is configured to position said light dot by means of an operator rotating said wheel according to an arc of rotation, along an internal part of said wheel, coinciding with the position of said fixed luminous dot or beam and coinciding with the desired position for an application of at least one of the correction masses.

2. The machine according to claim 1, comprising an input command of a measured desired position of at least one of the correction masses is effected by pressing a button.

3. The machine according to claim 2, wherein said measured desired position of said at least one of the correction masses is set manually.

4. The machine according to claim 1, comprising an input command of a measured desired position of at least one of the correction masses is effected by impacting said wheel, said impact being perceived by means of acceleration measurement systems.

5. The machine according to claim 1, comprising an input command of a measured desired position of at least one of the correction masses is effected by impacting said machine, said impact being perceived by means of acceleration measurement systems.

Description

(1) Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

(2) FIG. 1 is a partially sectional schematic view of a balancing machine according to the invention;

(3) FIG. 2 is a sectional view, in enlarged scale with respect to the preceding one, of the machine according to the invention;

(4) FIG. 3 is a partially sectional schematic view of a balancing machine according to a further aspect of the invention;

(5) FIG. 4 is a sectional view, in enlarged scale with respect to FIG. 3, of the machine according to the invention;

(6) FIG. 5 is a schematic view of the trigonometric calculation system for obtaining the value of the diameter of the rim, by means of the machine of FIGS. 3 and 4;

(7) FIG. 6 is a perspective view of a constructive example of the balancing machine according to the invention;

(8) FIG. 7 is a perspective view, in enlarged scale with respect to the preceding one, of the constructive example of the balancing machine according to the invention.

(9) With reference to the cited figures, the balancing machine according to the invention, designated generally by the reference numeral 1, includes a precision flange 4 on which a wheel 2 which includes a rim 3 is mounted.

(10) The wheel 2, fixed to the precision flange 4, is turned so as to reproduce the fixing that is present on the vehicle, i.e., so that the rotation axis of the wheel is the same one that can be found in operating conditions.

(11) The precision flange 4 is mounted on a supporting structure 41.

(12) By virtue of the rotation, the centrifugal forces generated by the imbalance become manifest and are measured by sensors located in the machine 1.

(13) According to the present invention, the balancing machine 1 includes a laser pointer 6 mounted on the supporting structure 41.

(14) The laser pointer 6 rotates about an axis that is perpendicular to a plane that contains the axis of the wheel 3 mounted on the shaft 8 of the balancing machine 1.

(15) The rotation of the laser pointer 6 is provided for example by a step motor, which is not visible in the figures and is controlled by a computer 5.

(16) When the step for mounting and locking the wheel on the shaft 8 ends, the procedure for acquiring the dimensions of the wheel 2 is started.

(17) The procedure includes the measurement of the inside diameter of the rim 3, the axial distance of the first correction plane and, for wheels that provide for correction with adhesive weights, the axial distance of the second correction plane.

(18) In order to acquire the diameter of the rim 3 it is possible to proceed manually, entering in the software of the computer 5 the diameter of the rim.

(19) Once the diameter of the rim 3 has been defined, one proceeds with the acquisition of the position of the correction planes.

(20) This operation consists in actuating the movement of the laser indicator 6 until the laser dot coincides with the axial position chosen for a correction plane, and subsequently with the position suitable for the second correction plane.

(21) At this point, knowing the diameter of the rim and the angle to which the motor has brought the laser indicator, the axial position of the correction planes is defined.

(22) Assuming a laser pointer 6, the angular movement of which is measured as shown in FIG. 2, wherein

(23) α, which is known, is the angle of the laser indicator formed from the inactive position; the point P on the rim that corresponds to the position of the chosen correction plane;

(24) γ is the angle formed by the perpendicular line that is radial to the rim and by the straight line that projects the point P;

(25) r can be traced back by construction to the radius of the wheel, which is known;

(26) the distance between C and P is the horizontal offset between the source of the laser pointer 6 and the point P, i.e., the axial position of the correction plane starting from a point with a known distance from the measurement system.

(27) From simple calculations one therefore finds that:
CP=r tan γ

(28) Therefore, if the diameter of the rim 3 and the angle defined by the angular displacement of the laser indicator 6 are known, the balancing machine 1 according to the invention is capable of knowing the axial position P of the correction plane.

(29) A simple and convenient way to control the angular movement of the motor that turns the laser pointer 6 along the internal surface of the rim 3 can be to use the rotation of the wheel 2 mounted on the balancing machine; each balancing machine has an angle sensor which measures the rotation of the shaft 8.

(30) This is indispensable for the measurement of the position of the imbalance.

(31) When the machine is not moving, the manual rotation of the wheel can be measured by the same angular sensor connected to the shaft of the balancing machine and, by means of the computer 5, this rotation can be used to control the laser pointer 6.

(32) In this manner the operator can easily move the dot of light inside the rim 3 and this allows a very simple and quick positioning of the laser pointer 6 at the correction plane.

(33) Once the laser pointer 6 has been positioned in the point chosen by the operator, confirmation for selection to the computer of the balancing machine can be performed in various manners, for example, by pressing a dedicated button 7 or by performing this confirmation by giving an impulse to the wheel 2 mounted on the shaft 8 of the balancing machine, for example a gentle bump with a fist.

(34) This impulse is perceived by the force sensors within the balancing machine, which are already present in order to acquire the imbalance values during the imbalance measurement step.

(35) The computer, by means of appropriate filters, is capable of receiving the signal that arrives from the force sensors and of interpreting this signal impulse as confirmation by the operator of the position of the correction plane, and of therefore storing the value of the angle or translation of the laser pointer at that given moment.

(36) This procedure, correlated with the displacement of the laser pointer by means of the manual rotation of the wheel, allows to use as interface between the operator and the balancing machine the wheel alone, simplifying the operation and making it straightforward to understand.

(37) As an alternative to the sensors of the balancing machine, the same function can be obtained with independent vibration sensors capable of detecting an impact.

(38) FIGS. 3-5 show a constructive example of the balancing machine, designated by the reference numeral 101, according to a further aspect of the invention, wherein the same reference numerals of FIGS. 1-2 designate substantially similar elements.

(39) One possibility to render the data setting operation more complete is a system that allows the acquisition of the diameter of the wheel 2.

(40) Instead of proceeding manually with the entry in the software of the diameter of the rim 3 it is possible to obtain the diameter of the rim by means of a line or dot laser emitter, designated by the reference numeral 9, which can be defined as a collimator and generates a dot or a line of light on a section of the rim 3.

(41) The angle between the luminous path generated by the collimator 9 and the shaft of the balancing machine, which is fixed and is defined mechanically, is known, and the distance between the collimator 9 and the laser pointer 6 also is known mechanically. A diagram of the solution can be seen in FIG. 3.

(42) The method to be followed in order to obtain the value of the diameter is to make the laser dot generated by the laser indicator 6 coincide with the projection of the dot or line generated by the collimator C that corresponds to the point P (FIG. 4). For that angle measured in the rotation of the laser indicator there exists a single rim diameter value.

(43) By means of simple trigonometric calculations it is in fact possible to obtain the value of the diameter, with particular reference to FIGS. 4 and 5:

(44) if the following are known:

(45) the angle α, defined as the angle formed by the laser indicator with the collimation point P;

(46) the angle γ, defined as the angle formed by the perpendicular line that is radial to the rim and by the collimation point P;

(47) the angle β, defined as the angle formed by the collimator with the axis of the shaft of the balancing machine, which is fixed and known by design;

(48) the distance SC, which is fixed and known by design;

(49) having as unknown r, a distance which can be traced back by construction to the radius of the wheel;

(50) it is possible to obtain that:
SP cos γ=RP=r
SP sin γ=(SC+CR)
CP cos(β−90°)=r
CP sin(β−90°)=CR

(51) By substituting one obtains r, which can be traced back to the radius of the rim:

(52) SC coty
______=r
1−tan(β−90°)coty

(53) It is therefore possible to obtain the value of the diameter of the rim by making the laser pointer coincide with the point generated by the fixed collimator.

(54) The procedure for moving the laser pointer is the same one that is followed during the step of acquisition of the correction planes, as described above, or can be obtained by means of the manual rotation of the wheel; likewise, confirmation on the part of the operator can be performed by giving a slight impulse to the wheel, as described above.

(55) The complete procedure can be summarized as follows: mounting of the wheel on the shaft of the balancing machine; acquisition of the first correction plane by means of the movement of the laser pointer by means of the manual rotation of the wheel and subsequent confirmation, for example with a bump of a first on the wheel; manual entry of the diameter of the wheel in the software of the balancing machine, or by arranging the pointer on the dot or line produced by the collimator and subsequent confirmation, for example with a bump of a first on the wheel; in the case of aluminum wheels, acquisition of the second correction plane by means of the movement of the laser pointer by means of the manual rotation of the wheel and subsequent confirmation, for example with a bump of a first on the wheel; measurement of the imbalance; correction of the imbalance, in which the laser pointer indicates the points at the counterweight application position; the axial positions of these points are the same ones acquired during the calibration step, stored by the electronic systems, and repeated so that the operator is facilitated in determining the position where the counterweights are to be applied.

(56) The balancing machine according to the present invention allows the acquisition of the dimensions by means of a laser pointer (spotter) but without the need for a gauge, acquiring the dimensions before measurement and indicating the correction position after measurement.

(57) In summary, the procedure according to the invention includes the following steps: mounting of the wheel; acquisition of the dimensions of the wheel by means of the laser pointer; measurement launch of the wheel, where the machine calculates the imbalance values; the wheel stops, the laser turns on and indicates the axial position of the first plane and of the second plane, in order to position the counterweights in a more effective and precise manner.

(58) An important advantage of the balancing machine according to the present invention is constituted by the fact that it includes only the laser pointer 6 and does not have a gauge.

(59) Therefore, the machine avoids the disadvantages of machines with a gauge and avoids the use of the triangulator and the disadvantages linked to this technology.

(60) A further advantage is constituted by the optional use of the fixed line or dot laser pointer, the collimator 9, to acquire the wheel diameter.

(61) In practice it has been found that the invention achieves the intended aim and objects, a system having been provided which is capable of extending the advantages of a compact and reliable system, such as that of the simple laser pointer, also to the wheel dimension acquisition step, whereas until today they were used only in the imbalance correction step, developing a new technique and a new method of acquisition that allow to obviate the mechanical limitations of current systems with a gauge and the reading limitations and the costs of current optical triangulation systems.

(62) The machine and method according to the invention offer distinct and considerable advantages over the prior art of record.

(63) For example, while US2005/132786 discloses a scanning device that “includes two lasers each of which is movable relative to a wheel by stepper motors . . . ”, according to the present invention there is no need of a “scanner device” or a scanner apparatus. The system according to the present invention includes two laser emitters, one of which is fixed, and the other that moves along the direction of the circle.

(64) On the other hand, US2005/132786 merely suggests a method for analyzing the geometry of the edge of a rim in order to define the most suitable clip-on counterweight.

(65) Also, while US2005/132786 provides that the dimensions of the edge of the rim of the wheel are measured using one of a laser, according to the present invention there is no need to carry out measurements of the profile of the rim edge.

(66) Also, while US2005/132786 refers to “laser distance meters”, i.e. triangulators, scanner device, according to the present invention the laser pointers are just pointers that are not ether triangulators or “laser distance meters”.

(67) Also, in the system according to the present invention, there is no need of displaying a graphical representation of a profile of the measured rim.

(68) While U.S. Pat. No. 6,244,108 discloses a correction method based on a laser pointer wherein the wheel dimensions are measured with a caliper which is physically mounted on the rim, and, after the wheel is spun in order to measure the imbalances, the laser pointer indicates the correction point, according to the present invention the laser pointer is only used to measure the wheel dimensions but the gauge is not physically mounted on the rim.

(69) Prior art document U.S. Pat. No. 6,484,574 specifically discloses the joint use of an automatic rotation of the wheel in the correction position and of a laser pointer that indicates the correction point. U.S. Pat. No. 6,484,574 clearly discloses to take the measurements with the caliper, defined as “automatic rim measuring component” which scans a contour. On the contrary, according to the present invention, no such device is need and no such operation has to be performed.

(70) The present invention allows the acquisition of the dimensions through two simple laser pointers, without the need of triangulators, gauges, nor any other system that measures the dimensions.

(71) This application claims the priority of Italian Patent Application No. 102020000008923, filed on Apr. 24, 2020, the subject matter of which is incorporated herein by reference.