DE1648674A1 - Device for determining the position and size of imbalance forces on vehicle wheels - Google Patents

Description

REPCO RESEARCH PROPRIETARY LIMITED Dandenong, Victoria, Australia

concerning

Device for determining the position and size of unbalance forces

on vehicle wheels »

The invention relates to a device for determining the position and size of imbalance forces on vehicle wheels, which belongs to the class of devices in which a vibration due to an imbalance force is related to the phase angle with respect to an arbitrary reference mark by means of a device for generating stroboscopic Lightning is analyzed while the wheel to be examined is lifted from the ground and set in rotation.

Up to now it was common to measure the unbalance at the resonance frequency the suspension, since at this frequency there is a phase shift regardless of the amount of damping of 90 ° between force and deflection, the resonance point is indicated by the on a measuring instrument Maximum deflection of the vibrating parts is determined »

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However, this approach is often unsatisfactory because some Suspensions do not have a pronounced resonance point and there are several resonance points in other suspensions occurrence. .

The one with the determination of the resonance point of the suspension connected subject part can be avoided, if that, Had turned alternately in both directions and the straboscope flash observed at a predetermined speed; will. the Angular relationship between force and deflection, although is not always predictable; becomes for both rotationiqh - be equal, which is why the bisector to the two- =, indicates the true direction of the imbalance force for the observed positions.

The essential object on which the invention is based is therefore an electronic device for displaying the location to create an imbalance force on a vehicle wheel: the wheel being lifted from the ground and rotating during the measurement is offset »In the preferred method of measurement, one accelerates the wheel to a speed that is greater than a predetermined one Speed is, and then allows it to rotate freely, the speed gradually decreasing.

The electronic device according to the invention comprises a ^ Device for generating a series of pulses which have a during the rotation of the wheel due to the imbalance force generated vibrations have a corresponding repetition frequency

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and one responsive to the pulse repetition rate Circuit which is connected to a stroboscopic flash device so that it is in operation at the time is set at which the speed of the wheel is set to a predetermined value has decreased.

The invention is illustrated below with the aid of a thematic Drawings explained in more detail using an exemplary embodiment. It seigeni

j? ig.1 a mobile unit, which the invention G-device and means to set the wheel in rotation, includes;

2 shows a scanning unit to be arranged under the Eahrsugboden j '".'." -.

Pig. 3 one on the instrument panel of the drivable ' Unit arranged "pointing device;

Eig.4 a circuit diagram of the electrical * · niche 3-device and

Figo is a Sehalt diagram of a Keß circuit for the Circuit according to Fig. 4

In Fig.1 is a mobile unit with a G-housing shown. The G-ehi-iu.ve encloses the inventive electrical

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Niche device and an electric motor for driving a fast rotating friction wheel 10a, with which the vehicle wheel can be set in rotation. The engine can over Switches operated by means of a foot pedal are activated will."

A scanning unit T1 is shown in FIG. The scanning unit includes a scanning head 12 which is connected to the electronic The device is connected in the housing 10 via a flexible hose 13. The scanning head 12 comprises an air bellows, the compressed air fluctuations generated by the The vibrations generated in the vehicle wheel depend on the unbalance force. The hose. 13 is long enough to pass during the examination of a Hades up to a nozzle 14 on the mobile unit .. ,, .. ·

The housing 10 includes an instrument panel 15 '' which attaches a pointer device 16 shown in FIG is. The 'housing also includes a protruding hood 17, which encloses a flash tube and a reflector.

The pointer device 16 comprises two adjustable pointers 18 and 19 and a scale 20.

The electronic device, the circuit diagram of which is shown in Fig. 4 is shown includes an amplifier circuit 22. The air pressure fluctuations generated by the scanning head 12 will be by means of a not shown. Converter in housing 10 in

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a substantially sinusoidal electrical signal is converted, which is fed to the input circuit of the amplifier circuit 22. The device according to FIG. 4 also includes a converter circuit 23 * connected to the amplifier 22, in which the sinusoidal, amplified signal is converted into pulses * which occur synchronously with the passage of the sinusoidal signal through a certain point on the curve. If the vehicle wheel is set in rotation during the examination, there is a series of pulses at the output of the converter circuit 23 with a repetition frequency corresponding to the vibration generated by an imbalance force. With increasing speed of the vehicle wheel, the pulse frequency also increases. In a corresponding manner, with decreasing speed of the vehicle wheel: the pulse track frequency also decreases. . -------

The electronic device according to Fig..4 also includes a circuit "24" which responds to the pulse repetition rate To this end, circuit 24 is connected to the output of the converter circuit 23 connected in order to generate further pulses from the pulses emitted by this circuit, their height or amplitude depends on the following frequency of the first impulses.

The circuit 24 includes a transistor 25, in which Kollektorlcrei3 a resistor 26 is connected, which is connected to "a Capacitor 27 is bridged, so that a network with a time constant is formed, which is in the order of magnitude of the Pulse frequency lies, which is at the predetermined speed

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adjusts .. 'Iformally- the transistor25 is blocked * but is opened by the pulses .: In this way, the circuit generates a sawtooth-shaped wave, the amplitude of which decreases with increasing pulse repetition frequency.

In a circuit 28, the pulses generated by the circuit are used to put a stroboscope flash circuit into operation at the point in time at which the vehicle wheel is rotating at the predetermined speed at which the unbalance measurement is to be carried out. Circuit 2B comprises a resistor 29 and a capacitor 30, which work together as a differentiating circuit for differentiating the sawtooth wave. The amplitude of the differentiated pulses will thus increase as the pulse repetition rate decreases. The circuit 28 further comprises a transistor 31, the base of which has been supplied with the differentiated pulses. The transistor 31 is normally blocked and biased to it is such that it is only opened when the amplitudes of the differentiated pulses are greater than the voltage at the emitter of the transistor. The circuit of the transistor 31 is designed so that it does not tend to open _r have as to the potentials of the differentiated pulses erreient to certain of those pulse repetition frequency value which is established at the predetermined speed of the vehicle wheel "Thus, the circuit 28 utilized by the circuit 23 originating pulses not until the pulse repetition frequency has reached a value corresponding to the predetermined speed. ,

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The electronic device also includes a strobe flash circuit 32 »The circuit 32 is with the circuit 28 connected and comprises a trigger coil 33 and a flash tube 34 ·· ". -

The electronic device further comprises a measuring circuit 36 which is connected to the circuit 22 * The measuring circuit includes a measuring instrument 37 "on which the size of the unbalance force is indicated",

The electronic device shown in Figo4 is over a power supply 35 fed.

When using the device, the vehicle is raised in order to lift the had to be examined from the ground. the The scanning unit is then placed under the vehicle floor or the wheel suspension in an easily accessible location and raised until the readhead is compressed. At the sidewall of the vehicle tire is then clearly recognizable Marking attached as a reference point.

The movable unit is then attached to the under investigation Wheel rolled up until the rapidly rotating friction wheel 10a comes into contact with the edge of the tire tread, and the The scanning unit is connected to the movable unit via the Hose 13 connected.

The motor in the housing 10 is then put into operation,

to turn the wheel in the lirzeiaexai ^ n, and the

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The speed of the Ead.es is increased until it is greater than the speed at which the measurement is made target. The movable unit is then removed from the wheel and the wheel is allowed to rotate freely, gradually increasing its speed decreases. While, the wheel slows down, the starts Flash tube 34 to flash at the point in time at which the wheel rotates at the predetermined speed, and the position the reference mark on the tire established. The pointer 18 is then in the appropriate Position on the scale 20 (in this particular 3 example Mr. 10). In the same way, the wheel is then by means of the movable unit rotated counterclockwise, and

when it slows down and reaches the predetermined speed
is enough / the position of the reference mark is determined again as soon as the flash tube starts to flash, and the pointer 19 is brought into the corresponding position on the scale 20 (in this example Kr.8). An angle bisecting the two pointer positions (in the example by - "- Kr.9) indicates the position of the unbalance force and a weight to compensate for this force can be attached to the wheel at a point that is offset by 90 ° from the point shown is (in the example at Kr.12).

As the wheel slows down, the frequency increases vibration generated by the unbalance force and therefore also the repetition frequency of the impulses, consequently longer periods of time remain between the blocked states of the transistor 25 and the amplitude of the sawtooth-shaped Wave and the differentiated potentials gradually increases

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When the wheel has reached the predetermined speed, if the differentiated impulses & e have an amplitude which is enough to. the transistor 31 during the pulse duration to 'open and the strobe flash circuit is activated to start the flashing of the flash tube trigger

In this way, the strobe flash circuit and the associated flash tube both act as a tachometer | as well as a device for displaying the angular position of the unbalance force ο

The measuring instrument 37 gives a display which corresponds to the magnitude of the impulsive force.

Of course, other electronic devices, such as logic digital devices can be used in place of the transistor circuit, the Circuit is modified accordingly. '

Claims

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Claims (6)

Claims, 1. Electronic device for displaying the position of an imbalance force on a vehicle wheel during a measurement, too which the wheel is lifted from the ground and set in rotation, characterized by a device to generate a series of pulses, one of the vibrations generated during the rotation of the wheel by the imbalance force have corresponding repetition frequency, and by a circuit responsive to the pulse repetition frequency, which so with a strobe flash circuit is connected to that is put into operation at the time when the speed of the wheel has dropped to a predetermined value. 2 o Electronic device according to claim |, ge ke — ir-ir-ζ ei without t by a device for generating a series of pulses which have a repetition frequency corresponding to the vibrations generated during the rotation of the wheel by the imbalance force a circuit for generating further pulses, the amplitude potential of which depends on the repetition frequency of the first pulses, and by means which uses the pulses generated in this circuit at the predetermined speed to set a stroboscopic flash circuit into operation at the time, at which the speed of the wheel -is decreased to a predetermined value, wherein the wheel to a rotational speed - 109831 / OOSUS BAD ÖRßäiÄRO ims - 2 - which is greater than the predetermined speed, accelerates rotated freely with gradually decreasing speed 3 ο electronic device according to claim 2, -ge.kmarks by a device for generating a A series of pulses corresponding to the vibrations generated by the imbalance force as the wheel rotates have f repetition frequency, by a first circuit for generating further pulses, whose. Amplitude potential | depends on the pole frequency of the first pulses, and through one with the first circuit and one with a strobe flash circuit connected second circuit, which is the stroboscopic flash stance controls and so with the first circuit that it is connected by means of the circuit in the first circuit generated pulses is brought into the operating state when the wheel has reached the predetermined speed, so that the Strobe flash circuit operated at the time is, to which the speed of the wheel on a predetermined Value has decreased, whereby the wheel, which is on a speed that is greater than this predetermined speed, was accelerated, rotated freely with gradually decreasing speed ». 4. Electronic device according to claim 3, characterized in that the first circuit for Er ~ witness a sawtooth wave designed whose The amplitude decreases with the increase in the pulse repetition frequency, and that the second circuit for differentiating the say- 1M831 / OÖ5S -3- Tooth-shaped wave is designed to generate differentiated pulses, the amplitude of which increases with the decrease in the pulse repetition frequency, the second circuit remaining in the idle state until the differentiated pulses have reached an AmpI- " sets a predetermined speed in order to then put the stroboscopic flash circuit into operation. ·. _{t =} ■; ■■ ■; ■. ". ■■ 5. Electronic device according to one of the claims 2 to 4, g e k e η η ζ e ic h η et by a device to avoid the vibrations generated by the unbalance force into a substantially sinusoidal electrical signal convert, and through a circuit to convert the sinusoidal electrical signal into pulses that are synchronous with the passage of the sinusoidal signal through a certain Curve point occur in order to generate a series of pulses ^ which is the input circuit of the subsequent circuit can be supplied. 6. Electronic device according to claim 5 »g e k e η η records by a measuring circuit connected to the sine wave converter circuit is connected to give an indication of the magnitude of the imbalance force.