JPH0715423B2 - Method and apparatus for determining wheel imbalance - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a method and apparatus for determining the imbalance of rotating members, in particular wheels, and more particularly to dynamically measuring the unbalance of rotating members. To a possible method and device. Although the present invention is specifically discussed below with respect to wheel balance, it will be appreciated that the aspects of the present invention are applicable to other types of rotating members, such as rotors and the like. It will be understood that when the application refers to "wheels" what is actually counterbalanced is usually the wheel-tire combination, and "wheel" includes this combination.

BACKGROUND OF THE INVENTION Currently, two basic types of systems are available for determining the imbalance of a wheel having mounted tires. One of these types of systems is static, in which the wheels and tires remain stationary while any imbalance is determined. For example, the wheels are supported horizontally by a leveling type support having air bubbles or similar such indicators that are displaced from a central reference point by tire imbalance. Points around the wheel rim (strategic
By placing the appropriate weight on the point, the operator changes the position of the bubble indicator until the bubble indicator is brought to the reference point. The weights are then secured to the wheels at these points.

A second basic type of wheel balancing system, a dynamic balancing system, has been developed to provide a more complete indication of wheel unbalance and a method by which the unbalance is corrected.
nner) is provided. In a dynamic wheel balancing system,
The wheels to be balanced are mounted on a shaft which is rotated at a given rotational speed. Once the wheel reaches this required speed, a measurement of the lateral movement of the shaft due to the wheel unbalance or the force generated by the shaft is made. From these measurements, an indication of the size of the wheel unbalance and the position of the unbalance can be determined. While the dynamic balancing system can determine the position of the imbalance in a single plane, the method detects the counterbalancing centrifugal forces that are present in two planes, approximately the inner and outer planes of the wheel, Differentiated and corrected. Therefore, a more accurate correction of unbalance can be achieved. The wheels are then removed from the balancer.

Typically, the wheel rotation speed is 40% during dynamic unbalance measurement.
Holds constant at 0r.pm or higher. Such speeds have been used for several reasons. First, it is easy to measure the unbalanced force at high speeds because the magnitude of the unbalanced force increases with the square of the rotational speed. At high speeds, a very favorable signal-to-noise ratio is easily obtained. For other reasons, there is a generally accepted belief that wheels need to be balanced at a rotational speed that approximates road speed.

Borner and Jockson, U.S. Pat.No. 4,435,982, discloses an improvement in a dynamic balancer in which the rotational speed of measurement is reduced to less than 360 rpm and the measurement of imbalance separates the wheel drive system. , And the wheels are run in "coasting" mode.

Published British patent application No. 8833035 by Borner and Jockson
Issue 6 describes yet another improvement, which
The required speed of rotation has been further reduced to below 100 rpm, and the wheels can be manually rotated and coasted.

Machines embodying the PBorner-Jackson patents and applications are on the market. These balancing devices are characterized by making their unbalance measurements when coasting down to a speed equal to one or several predetermined speeds. This manually driven machine fulfills its function particularly well in this regard. However, this machine is often handled by inexperienced persons, but the wheels are hand spun substantially above the required presetting speed, and to slow the wheels to that speed. There is a problem that it takes time.

SUMMARY OF THE INVENTION In these machines, and other dynamic balancing devices known to the Applicant, the carrier for the rotatable shaft on which the wheels are mounted is fixedly mounted to a base or pedestal. The wheels are manually lifted and mounted on the axle so that they roll off the floor. This is a simple shape which is quite convenient when the wheels to be balanced are motorcycle or light car wheels. However, positioning and mounting are difficult and dangerous when the wheels are large and heavy, i.e. large automobile wheels or truck wheels.
A separate lifting device, such as a jack or forklift, is needed, with the two people needed to position and install the wheels. This greatly increases the time and expense required to balance these large heavy wheels.

Another problem that occurs when balancing large and heavy wheels is that the wheels are not easily portable, in which case it is often preferable to move the balancer towards the wheels.
While the hand powered machines described above are portable, the other balancing devices used to date are generally large devices that require permanent factory installation.

Accordingly, it is a general object of the present invention to provide a wheel that stitches the precision of other dynamic wheel balancing devices, but which is operable without the limitations they have. It is an object of the present invention to provide a new method and apparatus for determining the imbalance of the like.

Another object of the invention is to dynamically determine the unbalance of a wheel that does not require or use a predetermined rotational speed to perform the unbalance measurement, and thus perform the measurement in a substantially uniform time. To provide a new device for doing so.

Yet another object of the present invention is to dynamically determine the unbalance of a wheel to which the wheel can be mounted so as to substantially reduce the effort and risk associated with mounting large wheels in conventional operation. To provide a novel method and apparatus.

Yet another object of the present invention is to provide a novel apparatus for dynamically determining wheel unbalance that is portable, mobile and suitable for field use.

According to these and other objects, the present invention provides a novel wheel balancing system that does not use preset measured speeds and is therefore capable of determining wheel unbalance at any speed within the speed range. This is a multiplying D / which receives one or more output signals respectively provided by one or more force measuring transducers of a balancing device and provides them to a microprocessor. It has been found that it can be achieved by a balancing device using an electronic measuring circuit including an A-converter. The microprocessor compares the output signal above to a threshold level and sends a command signal to the converter to multiply the input signal by an amount, which is the input signal when the input signal is provided to the microprocessor. To be within a reasonable range. Therefore, regardless of whether the wheels to be balanced are rotated at low speed (resulting in a relatively low amplitude input signal) or at high speed (resulting in a larger amplitude input signal), these input signals are Once properly amplified to be within its operating range, it can then be processed in the microprocessor.

Furthermore, the present invention has found that the wheel balancer can be implemented at very low speeds by the upward regulation of the small signal obtained at low speeds. This can be advantageously applied to balancing devices where large wheels such as truck wheels are difficult and dangerous to install. Additionally, the present invention provides a novel system for a new dynamic counterbalance wheel that does not require the operator to manually lift the wheel onto a rotatable counterbalance. This system includes a horizontal rotatable balance shaft adapted to support the wheels to be balanced. This axis can be above and below the base of the balancer and the ground, and the base itself is preferably movable horizontally on the ground with wheels, rollers or skids. Therefore, the balancing device is a movable unit that can be brought upright to the wheels and the balancing axis is adjusted to a height that exactly aligns with the center of the wheels. After attaching the wheel to the shaft,
The axle is lifted until the wheels are off the ground. The wheels are then rotated and their imbalance is determined.
At that time, the rotation of the wheels can be stopped. The wheels can be stopped by simply impeding the wind pressure resistance and bearing friction that slows them down, the balancing device can be provided with a braking mechanism, or preferably the rotating wheels are such that the wheels are in light contact with the ground. And the contact is stopped by lowering the wheel until it stops. Then the weights needed to correct the imbalance are attached to the vehicle. When the wheel is lowered until it brakes its rotation, the wheel needs to be lifted in its entirety to properly position the compensation weights. The axle with the attached wheels is then lowered until the wheels are again placed on the ground, then the wheels are off-balanced,
And the balancer can be moved away from the wheels. In a preferred embodiment of the principles of the present invention, the up and down movement of the shaft relative to the base is tilted somewhat obliquely with respect to the vertical plane passing through the horizontal balancing axis. This shape allows the total weight of the wheel to be preloaded or the base of the balancer to be self-locking with a force that exceeds the maximum unbalanced force experienced in balance. This precisely sustains the vibrations caused by the unbalanced rotating wheels and minimizes spurious motions and vibrations not caused by the wheel unbalanced forces when the wheels are rotated.

This shape and the preload that achieves it increases the mobility of the device. The rotatable balance shaft and its associated bearing support structure, as well as the electronic devices that are actually relatively precise and sensitive, can be removed from the relatively sturdy and heavy base so that the base is: Can be transported without fear of damaging the counterbalance head,
The counterbalanced head can be better protected and transported itself. The preload compensates for the gap and absorbs the play between the balanced head assembly and the base (take u
p), whereby the gap between these two units gives rise to a very large incidental reassembly ease.

Implementations of the present invention that do not preselect the balancing speed work well for balancing large truck wheels,
Accordingly, although working in combination with these aspects of the invention with respect to the adjustable position axis have excellent advantages, it is understood that both of these aspects can be implemented separately. Will. Thus, for example, the use of non-preselected speeds can be incorporated into a balancing device such as described in Jackson and Borner, US Patent Application No. 444,885. Similarly, the adjustable positioning axis can be used with other measurement circuits.

The manner in which the present invention achieves the above objectives and attendant advantages will be fully understood by a reading of the following detailed description of the preferred embodiments of the invention illustrated in the accompanying drawings.

EXAMPLE Referring to FIG. 1 of the present application, the wheel balancer head 8 illustrated therein includes a frame 10 which includes all mechanical and electrical components of the balancer head. Provides a suitable structural support for. The frame 10 basically comprises an elongated tube having a generally square or rectangular cross section. The tube-shaped housing 12 is suspended from the top wall of the frame 10 so that it can conduct forces in only one direction. The support mechanism for the housing 12 includes a pair of metal strips 14 and 16, which in one horizontal direction,
That is, it is sufficiently flexible to allow freedom of movement in the direction indicated by AB in FIG. The metal strip is sufficiently rigid so that it is not subject to elastic compression or stretching, thereby restraining vertical movement of the housing 12. Furthermore,
The strips 14 and 16 are fixedly mounted on both the frame 10 and the housing 12, so that they cannot pivot in a vertical plane, and thus longitudinally, i.e.
Suppress vertical movement of housing 12 relative to AB. Vertical rod with additional support for housing 12
18 provided by strips 14 and 16
It is mounted on the side of the housing opposite the housing and allows the required freedom of movement of the housing.

The balance shaft 20 is properly journaled for rotation within the housing 12 by bearings 22. A mounting flange or plate 24 is attached to one end of the shaft 20 and provides a suitable bearing surface against which the wheel 25 to be balanced abuts when mounted on the shaft 20. A frustoconical hub mechanism can be screwed onto the axle 20 to lock the wheel to be balanced into position or otherwise the wheel is conventional as illustrated in FIGS. 2 and 3. Bolts and lugs to the plate 24.

The timing disc 30 has the shaft 20 on the opposite side of the mounting plate 24.
Mounted on the edge of. The disk 30 has a number of radial slots or marks arranged around its perimeter, which cooperate in a known manner with an electro-optical encoder 32 so that the disk 30 is thus associated with the shaft 20. It provides spatial pulse signals for the rotational position and velocity of the.

The lateral force generated by the rotation of the shaft 20 and caused by the measured wheel imbalance is
Sensed by piezoelectric electrical transducers 34, 36 projecting through and engaging the housing 12.
The base of the housing 12 may include a boss 40 which projects from the sides of the housing 12 such that the housing engages only the transducer elements 34 and 36 and bears against any other portion of the frame 10. Guarantee that you can not. Mounted on frame 10 and housing 12
A pair of spring-loaded bearing pins 41 engaging the
The housing is biased to engage the transducer both downward and laterally.

As is known in the dynamic tire balancing art, a transducer for detecting lateral movement of a rotating shaft due to wheel imbalance essentially consists of a shaft around a vertical axis passing through the center of the shaft. It must be located in two spaced-apart positions along the length of the axis to measure the turn.

Timing-Encoder 32 and Transducer 34 and
36 is mounted on a single printed wiring board 45, which also supports and properly interconnects all other electronic components for the wheel balancer. These electronic components include suitable conventional circuitry, which positions the position of the transducer output signal relative to the inner and outer rims of the wheel to be balanced and the rotational position of the wheel. Correlates to information about and provides an indication of the measured wheel imbalance. The information can be displayed on a suitable display device 48 mounted on the printed wiring board 45. The wiring board 45 includes a circuit for performing an imbalance measurement at an undetermined speed, which circuit will be further described with reference to FIG. The wiring board 45 can be attached to the frame 10 or to an outer cover (not shown) for the balancer head.

Additionally, the balance shaft 20 carries a crank 42, which is used to determine the unbalance of the wheels 25.
It is provided to rotate 20 and wheels 25. crank
42 is preferably designed so that when the wheels are spinning, the wheels only drive in one direction so that they do not cause dangerous rotation of the crank, and ferr-wheel in the other direction . This can be done, for example, by attaching the sleeve 43 attached to the crank 42 to the balance shaft 20 by a lap spring 44 or any other suitable one-way clutch device.

The counterbalance head assembly 8 is attached to the base 50 as shown in FIGS. The base 50 is designed to move up and down the head assembly 8 to align the shaft 20 with the center of the wheel 25 and the wheel bolts 26 into corresponding bolt holes on the wheel 25 for mounting the lug nut 8. .

This can be accomplished by attaching the head assembly 8 to a shelf 52, which further tilts the upright post 56.
It is attached to a carriage 54 that moves up and down. The position of the carriage 54 must be set by a relatively finely adjustable control, such as plus or minus millimeters, to allow precise alignment of the balancer head with the wheel lugs or the like. One means for making adjustments is driven through nut plates 78 on upright posts 56 by the use of shafts 76 which are threaded by a pair of crank driven miter gears. The crank 58 can be equipped with a handle 71. The miter gears 72 and 74 are surrounded by a gear cover 60. The bearings and constructions in which the shaft carrying the miter gear 72 is mounted on the carriage 54 are conventional and are not discussed herein for brevity. When the drive miter gear 72 is rotated, it further rotates the drive gear 74, and the threaded shaft 76
Is rotated to move the shaft up and down by the interaction between the nut plate 78 and the shaft. Stop nut 80 is provided at the end of shaft 76. The upright column 56 includes a cross member 61 and an arm 62.
Essentially "U" shaped cross member 61 made from
Installed on. This "U" shaped structure has wheels or rollers 66 and 68, which are rollers 66 and 68.
Can act when the balancer is tilted to move it to the wheel position. A skid 70 as shown in FIG. 2 or a rigid wheel 70A as shown in FIG. 3 is provided on the cross member to facilitate the final positioning of the balancer by the wheel, On the other hand, it provides a solid base for the balancing device during the balancing operation.

Note that nut plate 78 is simply placed on top of upright post 56, and the opening in upright post 56 is large enough to pass through the nut of nut plate 58.
Thus, the entire assembly of the balancer head 8 with associated table 52 and vertical positioning mechanism can be lifted away from the upright 56 for shipping or storage if desired. With this disassembly, the precision and more delicate balancer head can be disassembled from the heavy and durable base.

Preferably upright post 56 is a cross member when viewed along axis 20.
Note that it is not vertical to 61. The angle from the vertical, the angle "A" is shown as 10 degrees, but from about 3 degrees to about
It can be in the range of 20 degrees, especially 5 to 15 degrees.
This angle is such that when the wheel is mounted on axle 20, its weight loads shelf 52 and carriage 54 against upright post 56, and upright post 56 is made up of cross member 61 and arms 62 and 64. A twisting force is applied to apply a load to the lower structure. This load, which is a force greater than the unbalanced force created during the balancing operation, takes up any play or gap in the vane structure and minimizes the possibility of disturbing vibrations and harmonics within the balancing device itself. To

In operation, the wheels to be balanced are removed from the truck or placed in a vertical position. The balancer is located near the wheels. Operator is wheel bolt
Adjust the vertical position of the balancer head by rotating the crank 58 until the 30 is aligned with the corresponding hole in the wheel. The balancer is then pushed forward until the wheel bolt 26 engages the wheel hole and the wheel nut 28 is applied to hold the wheel. The exact method of mounting the wheels on axle 20 is not central to the practice of the invention. Instead of wheel bolts 26 and lug nuts 28, bolt plates and associated bolts can be used. Similarly, for a wheel having a precisely defined center hole, the wheel may be a center-hole-engaging cone system as is known in the art.
-hole-engaging cone system). Once the wheels are installed, the crank 58 is then rotated to lift the tires off the ground and up until the wheels are free to rotate.

The operator determines the distance of the transducer from the inward rim of the wheel being measured (ie, the transducer offset),
And information about the distance between the inner and outer rims of the wheel and the diameter of the wheel. Typically, this information can be economically determined based on standard wheel sizes, and a mechanism for including such information,
For example, the potentiometer 46 (Fig. 1) can be modified according to the size of a standard wheel. Once you have the right information,
The wheels are gripped by hand gripping the wheels or cranks 42,
And it works by applying a rotational force to it.

Wheel rotates to a speed greater than the required minimum speed (spin u
p), a signal is given to the operator to indicate that no further rotational force needs to be applied. This speed need not be greater than 180 revolutions per minute and is preferably substantially less than that. The balancer measures the unbalanced force and signals the operator that this is done. The wheel is then slowed down, for example by lowering the wheel until its tires drag on the ground. Once stopped, the wheels are lifted again, and the weights and their positions required for balancing are displayed on the display 48, and the weights can be applied to the wheels to counterbalance them.

According to yet another aspect of the invention, the measurement circuit is preferably capable of performing imbalance measurements within a relatively wide range of rotational speeds at any given speed. This type of circuit is particularly useful for this type of dynamic balancer, where the rotation is manually applied to the wheels and thus widely varies in speed due to the force applied by the operator. You can The change in rotational speed from one measurement to the next is particularly widely used in balancing devices adapted to accommodate various tire sizes, such as the tires described with reference to FIGS. 2 and 3. There is.

Referring to FIG. 4, in a circuit embodying this principle, the output signals from piezoelectric transducers 34 and 36 are amplified by amplifiers 102 and 104, respectively. The amplified output signals from these amplifiers are paired with a multiplying digital-to-analog converter (M
DAC) 106 and 108. In operation, the MDAC multiplies each analog input signal by a coefficient determined by the digital signal and then supplies the multiplied signal to the microprocessor 110. In a microprocessor, the analog input signal is converted to digital form by an internal converter.

The MDAC is first set up (the first measurement is taken before that time) and the signal is multiplied by a factor determined according to the value of the wheel speed, and also the wheel diameter. The value of the wheel diameter is fed into the microprocessor by a manually adjusted potentiometer 112. Wheel speed is measured. This coefficient is
Perhaps a signal multiplic that results in the amplitude of the input signal adjusted to the center of the operating range of the microprocessor
ation) can be determined empirically for different wheel types.

When the input signal is outside the operating range of the microprocessor because the input signal is so large, the MDAC directs to decrease the transducer input signal, i.e. multiply it by a factor less than one. If desired, MDACs can also be used to increase the amplification of low level signals caused, for example, by slow rotation speed. Once the input signal is properly adjusted, the microprocessor acts on it in a conventional manner to determine the unbalanced condition of the wheels. By limiting the operating range that the microprocessor has to work with, more accurate results are achieved at less cost. For example, an inexpensive microprocessor with a small (eg 8-bit) internal A / D converter can be used instead of an A / D converter with a large converter for widespread application.

The comparison of the input signal with the threshold value and the appropriate adjustment of its level can be carried out approximately with 3 to 5 revolutions of the wheel. Therefore, it is possible to perform this operation with each wheel measurement without losing a significant amount of time, especially compared to the time it takes to decelerate to a constant measurement speed, especially when a large wheel is first overspun. is there. Therefore, the wheel balancer having this rotation can be effectively used to balance different sizes of tires, each of which can rotate at different speeds.

More specifically, the output signals from the transducers 34 and 36 are passed through the amplification stages 102 and 104 and then through the appropriate filtering states to the 2-channel MDAC1.
Offered on 06/108. MDAC multiply these two input signals separately according to the 8-bit command signal received from the microprocessor 110 via the data bus,
It then produces two regulated output signals. Their output signals are pre-amplified in the buffer stage.
fication) and after processing provided to the microprocessor.

After the input signals have been adjusted to the correct level within the operating range of the microprocessor, the microprocessor, along with the signals from encoder 32, which indicate the angular position of the wheel and its direction of rotation, It is used to determine the unbalanced state of the wheels according to commonly used algorithms.

It will be appreciated by one of ordinary skill in the art that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Thus, it is believed that the presently disclosed embodiments are illustrative in all respects and should not be limiting. The scope of the invention is set forth by the appended claims rather than by the foregoing description, and all equivalent modifications and variations that come within the scope are intended to be included therein.

[Brief description of drawings]

1 is a perspective view of a typical shaft and measuring head arrangement for generating electrical signals related to avalanche forces; FIG. 2 is in accordance with the principles of the present invention and is shown in FIG. FIG. 3 is a perspective view of an adjustable positioning axle wheel balancer constructed using such a balance head; FIG. 3 is a front elevational view of the balancer as shown in FIG. 2; It is a schematic block diagram of the electric circuit part of the wheel balancer which does not use a predetermined measurement speed; 8 ... Wheel balancer head 10 ... Frame 12 ... Housing 14,16 ... Metal strip 20 ... Balance axis 25 …… Wheels 30 …… Timing disks 34,36 …… Piezo electric transformers 45 …… Printed wiring boards 48 …… Display devices 50 …… Base 54 …… Carriage 56 …… Upright columns 72,74 …… Miter gears 76 …… Screw Ivy axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-30781 (JP, A) JP-A-55-23495 (JP, A) JP-A-46-3051 (JP, A)

Claims (8)

[Claims] 1. A method of dynamically determining an unbalance of a wheel: erecting the wheel substantially perpendicular to the ground; a rotatable horizontal axis connected to a means for dynamically measuring the transmitted force. Vertically aligning with the center of the wheel and positioning the shaft by engaging the wheel with the wheel; mounting the wheel on the rotatable horizontal shaft; until the wheel clears the ground. Lifting said rotatable horizontal axis supported by a carriage mounted on said carriage and said measuring means; pre-loading the carriage to substantially reduce movement of the carriage during dynamic measurement of the imbalance. And; applying rotation to the wheel and shaft until the unbalanced force transmitted by the shaft is large enough to be measurable; A step of dynamically measuring the unbalanced force transmitted to the shaft while the movement of the carriage is reduced by a load; and a step of displaying the unbalanced data. . 2. In the step of pre-loading the carriage, while the dynamic imbalance is determined, a load having a force larger than the maximum value of the imbalance generated by the rotation of the wheel and the shaft is applied to the upright column. The method according to claim 1, wherein the carriage is preloaded on the carriage. 3. The method of claim 2 wherein the step of imparting rotation is performed manually and the achieved speed is not greater than 180 rpm. 4. A device for dynamically determining the unbalance of a wheel: a base; a carriage provided on the base, the height of which is adjustable by height adjusting means. A carriage guided to the carriage; a horizontal shaft arranged on the carriage, the horizontal shaft holding the wheels and having no rotary drive source and being able to hold the wheels on the ground A horizontal axis which is lowered together with it and is then lifted to a position in which the retained wheels are free to rotate; a wheel balancer head mounted on said carriage; A plurality of supports that are swingably supported on the wheel; and wheel ambers that are engaged with these supports and that are provided at two points spaced apart in the axial direction. Apparatus characterized by having: a transducer and measuring the force of Nsu; rotational speed of and the horizontal axis means notifying that has reached a predetermined rotational speed below 180 rpm. 5. The carriage moves vertically along an upright column, and the upright column is inclined at a predetermined angle to a vertical plane which is parallel to the front plane of a wheel standing vertically and which passes through the horizontal axis. 5. The apparatus of claim 4, wherein the carriage is pre-positioned and when the wheels are lifted off the ground, the weight of the wheels preloads the carriage against the upright posts. 6. The apparatus according to claim 5, wherein the predetermined angle is 3 to 20 degrees. 7. The apparatus of claim 6 wherein said predetermined angle is about 10 degrees. 8. When the device tilts from a position that determines the unbalance of the wheels, a roller attached to the base contacts the ground to allow the device to move in the direction of the upright wheels, while 8. An apparatus according to claim 7, wherein the base is fixed to determine the unbalance of the wheels without the roller contacting the ground when is in a position for determining the unbalance of the wheels.