DE2411843A1 - DEVICE FOR BALANCING ROTORS, IN PARTICULAR MOTOR VEHICLE WHEELS - Google Patents

Description

2411843 Patent attorney Dipl.-Phys. Gerhard Liedl 8 Munich 22 Steinsdorfstr. 21-22 Tel. 29 84

C 6626

Gebr. HOFMANN K.G., Maschinenfabrik 61 Darmstadt, Pallaswiesenstrasse 72

Device for balancing rotors, in particular Motor vehicle wheels

The invention relates to a device for balancing rotors, in particular motor vehicle wheels with an unbalance measuring device for measuring the unbalance according to angular position and, if necessary, size and with a positioning device for turning the rotor into a position in which the unbalance compensation can take place.

From the German Auslegeschrift 2 213 449 it is known in the balancing of rotors, in particular motor vehicle wheels, according to the Measurement run, in which the unbalance was determined according to position and size, the rotor in the position with the help of light signals

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screw in, in which the unbalance compensation can take place. at In this known device it is necessary to move the rotor by hand screw into the balancing position in which the balancing weights can be attached.

The object of the invention is therefore to provide a device for balancing of rotors to show in which the turning of the rotor into the position in which the balancing process is carried out can be carried out automatically, with the rotor remaining on the same spindle on which the measurement run was carried out can.

This task is performed with the device of the type mentioned at the beginning solved according to the invention in that a direct current motor is provided both for the measuring cycle and for the positioning and that by means of a changeover switch, the direct current motor from the voltage supply source during the measuring cycle to a braking device and when a certain reduced speed is reached from the braking device to a position controller of the positioning device can be connected, the position controller from both the unbalance measuring device as well as depending on the angular position of the rotor or the speed of the DC motor.

A significant simplification of the balancing machine results from the fact that for the speed-dependent control of the position controller the back EMF is scanned by the DC motor and fed back to the position controller, so that then during positioning the control loop is closed without using a tachometer generator or a phase encoder.

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The position controller can be designed in a suitable manner as a comparison circuit that depends on the comparison of the Unbalance measuring device supplied signal and the sampled back EMF of the DC motor a control signal to the DC motor supplies. A shunt motor is preferably used as the direct current motor.

It is advantageous to feed the position controller via an isolating transformer so that there is no potential in the position control loop. This makes it possible for the power for the position controller to be designed to be very small, since only during positioning Frictional forces are to be overcome.

When positioning the unbalance measuring device delivers in an advantageous manner Way, as a positioning setpoint to the position controller, a signal whose polarity is positive in a 180 -angular range and in the

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other 180 -angle range is negative, with the zero crossing this signal indicates the angular position of the unbalance. This ensures that when positioning the motor in place is stopped at which it is no longer supplied with voltage by the position controller, i.e. at the point where the imbalance is.

In the invention, the switching sequence is compulsory after the measurement run has been carried out. With the help of a selector switch you can. differentiate between the "balancing" and "positioning" modes. With "balancing" the DC motor is charged with a fixed setpoint via a speed controller. The investigation the unbalance in terms of size and direction takes place in a known manner. When "positioning", the motor is braked, using a monitoring device waits for a low speed and then switches over to the position controller. As a setpoint

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a signal from the measuring electronics is used for positioning, whereby the determination can be carried out in accordance with German Auslegeschrift 2 213 449.

The advantages which are achieved in particular with the invention can be seen in the fact that only a small amount of technical effort is required, with the means for controlling on or within the Balancing machine can be attached.

In the accompanying figures is a preferred embodiment of the invention shown, and it is based on this embodiment the invention will be explained in more detail. Show it:

Figure 1 is a block diagram of a balancing device and

FIG. 2 shows the voltage supplied by the positioning device as a positioning setpoint, which during positioning is applied to the DC motor.

A stabilized DC voltage source 1 is used to supply the individual assemblies. A rectifier 2 with a fixed output voltage is used for the immediate supply of the DC motor. The implementation of the Meßlaufes ( "balancing") and the "positioning" is carried ^f in three steps serve this purpose, the speed controller, consisting of the current and speed control amplifiers 4, _3:. Diode an ignition unit 5, and a semi-controlled thyristor bridge circuit with additional freewheeling 6 consists, a braking unit 8 and a position controller, which consists of a position control amplifier 12 and an additional rectifier bridge 13. The position control amplifier 12 is designed as an integrated circuit.

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A selection switch 7 can be used to set three operating modes , namely standstill-positioning-balancing. In connection with a switching device 9, which has a direct current motor 15, which acts as a drive motor for balancing as well as for positioning is used, and a monitoring device 14 results in a compulsory Switching sequence. Due to this switching sequence, the DC motor 15, which is a DC shunt motor, while for balancing is connected to the speed controller and supplied with voltage via this. The armature voltage is changed through phase control of the half-controlled thyristor bridge circuit 6. with the additional freewheeling diode. By changing the ignition angle of the thyristors, the armature voltage of the DC motor can be adjusted continuously. Long pulses are used for ignition, starting from the actual ignition point up to End of the network half-wave. The ignition pulses are synchronized with a special circuit for interference suppression, which reliably prevents the thyristors from igniting via mains interference pulses. The ignition angle adjustment is made by the output signal the speed and Current control amplifier 3, 4 reached. An integrated circuit is used as the current control amplifier 4. The target / actual value comparison takes place by resistance mixing at the non-inverting input. Limiting the maximum setpoint creates a limitation the maximum output current of the thyristor bridge 6 is reached. The control behavior can be adjusted by R-C shading; influence. . A DC-side is used to record the actual value of the current Shunt inserted. As a result, the control circuit is connected to the mains potential. An integrated speed controller amplifier 3 is also used Circuit used. This compares the target value obtained from a stabilized voltage with one from the speed derived actual value and leads to a change in the event of a deviation

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the current setpoint specification by a speed correction. The speed controller amplifier 3 can be influenced in its behavior by R-C wiring.

With DC shunt motors - as such is the DC motor 15 - there is a fixed relationship between speed and armature voltage. It can thus be a speed control can also be done indirectly via armature voltage regulation. Since the current proportional voltage drop across the ohmic resistance of the Armature can be derived from the flowing armature current, it is possible to automatically reduce the resulting drop in speed Compensate setpoint correction (IxR compensation).

When "balancing" the size and the angular position of the unbalance is determined by a measuring device 10, 11 and stored. By Switching over the selector switch 7, the "positioning" mode is preselected, whereby the braking of the DC motor 15 by the braking unit 8 provided for this purpose takes place. For this purpose, the armature of the externally excited direct current shunt motor is activated by the switching device 9 15 from .the supply voltage, i.e. from the speed controller, separated and on the brake unit 8, which as Load resistor is formed, switched. The monitoring device 14, which is designed as a speed measuring device, monitors this resistance braking and switches at a certain low speed via the switching device & the load resistance 8 from. At the same time, the position controller 12, 13 is switched to the armature circuit of the DC motor 15.

The position controller is fed via an isolating transformer 16, which means that there is no potential in the position control circuit. the The armature voltage is changed by evaluating a trans-

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sistor circuit with additional rectifier bridge 13. Through If the control voltage is changed, the armature voltage can be continuously adjusted in a positive and negative direction. For adjustment the output signal of the position control amplifier 12 is used.

The position control amplifier 12 is designed as an integrated circuit. This compares the setpoint signal made available from the measuring electronics 10, 11 with one derived from the speed Actual value (motor back EMF) and transfers in the event of a deviation a change in the output signal a correction of the speed or speed direction by. With an IxR compensation and R-G circuit the controller behavior is also corrected or influenced in the case of the position control amplifier 12.

A DC voltage is available as the positioning setpoint the angular position of alternating polarity available, as shown in FIG. This DC voltage is about a Angular range of 180 positive and over a wider angular range of 180 ° negative. The zero crossing of this DC voltage is called the angular position of the unbalance. In FIG. 2, the unbalance would have an angular position of 0. The voltage form shown is the same for other angular positions of the unbalance, with the stress only increasing by the corresponding number of degrees on the abscissa is shifted.

The positioning takes place in such a way that the position controller 12, 13 is acted upon by the setpoint signal of the measuring electronics in such a way that, the drive of the DC motor 15 moves in the direction of the angular position of the unbalance. The setpoint is reduced to Zero volts when the engine is at a standstill.

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Claims (8)

Claims IJ Device for balancing rotors, especially motor vehicle wheels with an unbalance measuring device for measuring the unbalance according to the angular position and, if necessary, size and with a Positioning device for turning the rotor into a position in which the unbalance compensation can take place, characterized in that, that a direct current motor (15) is provided both for the measuring cycle and for the positioning and that by means of a changeover switch (7 or 9) the DC motor from the voltage supply source during the measuring cycle to a braking device (8) and when it is reached a certain reduced speed can be connected to a position controller (12, 13) of the positioning device, the position controller both from the unbalance measuring device (10,11) and depending on the angular position of the rotor or the speed of the DC motor is controlled. 2. Apparatus according to claim 1, characterized in that the position controller (12, 13) is fed potential-free via a transformer (16) and is designed for low power. 3. Apparatus according to claim 1, characterized in that the position controller (12,13) is designed as a comparison circuit and depending on the comparison of the signal supplied by the unbalance measuring device (10, 11) and the control signal from the angular position of the rotor or the speed of the DC motor depends, supplies a control signal to the DC motor (15). 6626 509 8 40/0460 4. Device according to one of claims 1 to 3, characterized in that that the direct current motor (15) is designed as a shunt motor. . 5. Device according to one of claims 1 to 3, characterized in that that the position controller (12, 13) is fed via an isolating transformer (16). 6. Device according to one of the Anspiü before 1 to 5, characterized in that that the position controller controls the direct current motor (15) via a rectifier bridge (13). 7. Device according to one of claims 1 to 6, characterized in that that the position controller is designed as an integrated circuit "is.""^;'■■ -. · ■■ · .- ■■ ■.; -." ... ■■ 8. Device according to one of claims 1 to 7, characterized in that that the measuring device supplies a signal as the positioning setpoint, the polarity of which is positive over an angular range of 180 and is negative over a wider range of 180, where the zero crossing of this signal is at the angular position of the unbalance * 6626 509840/0460 Empty soap