CH643654A5 - MACHINE FOR CONTROLLING A TOOTHED WHEEL. - Google Patents

Description

The invention will be described in more detail with reference to the drawings annexed by way of example and in which:

fig. 1 is a simplified diagram of the part of the machine according to the invention intended for controlling the center distance;

fig. 2a and 2b are simplified diagrams of the part of the machine according to the invention intended for displaying the results;

fig. 3 is a simplified diagram of the part of the machine according to the invention intended for measuring the involute;

fig. 4 is a simplified diagram of the part of the machine according to the invention intended for measuring the pitch and the accuracy;

fig. 5 is a simplified combined diagram of the sensors and amplifiers of the carrier;

fig. 6 is a simplified combined diagram showing the processing circuits of type A;

s fig. 7 is a simplified combined diagram showing the type B processing circuits;

fig. 8 is a time diagram showing the waveforms encountered in the circuit shown in FIG. 7;

fig. 9 is a simplified and combined diagram of the type C treatment circuit forming part of the machine according to the invention, and FIG. 10 is a simplified and combined diagram of the circuit associating the pitch error and taper signals.

Fig. 1 represents a part of the gear control machine according to the invention, used for the detection of center distance errors. A toothed wheel 20 to be checked is mounted on a spindle 22 driven by a control motor 24. A toothed wheel model 26 meshes with the wheel 20 to be controlled and is mounted on a spindle 28 which projects from a support 30 carried by a bar 32 so that it can be moved against the force of a spring 34. The particular type -20, the support link used for the model 26 wheel does not constitute an important characteristic of the invention and other types of conventional sliding carriages can be used.

The bar 32 carries an arm 36 which can come into contact with the probe 38 of a linear voltage differential transformer 40. The output signal of this transformer 40 is transmitted to a carrier amplifier 42 described in more detail below. . The model wheel, mounted on the mobile control slider, is rotated and the variation in the spacing between the axes 21 and 27 of the toothed wheels forces the slider to move. The amplitude and frequency of these 30 movements are directly proportional to the faults or errors presented by the toothed wheel during inspection. The signal thus produced by the transformer 40 and transmitted to the carrier amplifier 42 is therefore proportional to the movements composed of the center distance of the model wheel. When the components of this signal 35 are separated from each other and measured with precision, they give the amplitude of certain particular characteristics of the toothed wheel.

The machine according to the invention will be described in a particular embodiment in which a certain number of characteristics of the toothed wheels are controlled. However, it is obvious to a person skilled in the art that a machine of the type described can easily be adapted for the control of various other characteristics of toothed wheels by the implementation of modified circuits. The characteristics of the toothed wheels checked in the part of the machine shown in fig. 1 are:

- the thickness of the teeth

- the total false round or the compound error

- the partial false round

- tooth to tooth action 50 - notches

The differential transformer 40, which transmits the center distance signal to the carrier amplifier 42, can be a conventional detector of the type comprising a movable plunger to which a ferrite core is fixed. The transformer body being held in a fixed position, the detection plunger 55 moves the ferrite core inside the transformer-specific core, so as to determine the amplitude and the polarity of the electrical signal applied to the secondary winding of this transformer. The carrier amplifier 42 comprises a low impedance power oscillator, applying a high frequency and low voltage signal 60 to the differential transformer by a line 44. A line 45 carries the input signal to the amplifier 42. For example , this signal can be a direct current signal of 2.5 V effective, with a frequency of 5000 Hz, making it possible to apply the requested excitation voltage to the primary winding of the differential transformer.

The carrier amplifier 42 also includes a demodulator for demodulating, filtering and amplifying the signal received from the differential transformer. Carrier amplifier 42 also includes

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Also an output stage which produces a strong signal representing the total compound displacement of the differential transformer plunger. The output signal from the carrier amplifier 42 therefore represents the total compound error of the gear wheel, and the various components of this signal are indicated by the waveform 46 of FIG. 1.

The separation of the components of the complex waveform 46 represented in significant characteristics of the toothed wheel can be described with regard to this waveform. A perfect gear wheel produces an output wave in the form of a straight line along the horizontal axis O. Any gear wheel to be controlled can have a dimension greater or less than the desired dimension and, therefore, a signal of medium size, represented by the distance between axis 0 and line 48,

can have a positive or negative value. The total runout error is indicated by the spacing of the lines 50 and 52 which represents the variation of the waveform 46 with respect to the line 48 when the high frequency components are eliminated. The maximum useful thickness of a tooth is indicated by the distance between the reference axis 0 and a line 54. When this distance is determined, the signals due to the cuts are eliminated by filtering.

The amplitude of a notch is indicated by the distance between the point at which the signal corresponding to the notch begins, this point being indicated by a line 56, and the peak or maximum value reached, indicated by a line such as the line 58. The action tooth to tooth is indicated between the two points associated with a tooth, as represented by lines 60 and 62. The minimum useful thickness of a tooth is indicated by the distance between the reference axis 0 and line 60. The total compound error is represented by the spacing of lines 58 and 60 and it includes all the signal peaks due to the notches. The gear control machine according to the invention is designed to separate these various components from the complex waveform 46, so that the values thus obtained can be recorded and / or used to give an indication when any of these signals exceed a limit previously established and adjusted to indicate the maximum deviation that can be tolerated for a particular toothed wheel.

The output signal from the carrier amplifier 42 is transmitted to a processing circuit 64 of type A intended to separate some of the components, described above, of the complex waveform 46. For example, the processing circuit 64 produces , on its output line 66, a signal representing the maximum useful thickness of a tooth or, as a variant, the maximum dimension of the toothed wheel. The output signal appearing on a line 68 of this circuit represents the average useful thickness of a tooth, or the average dimension of the toothed wheel. The signal appearing on a line 70 represents the compound error or the runout. The signal appearing on a line 72 represents the minimum useful thickness of a tooth or the minimum dimension of the toothed wheel (the output lines 66 to 72 can be used to transmit one or more signals representing different functions, on the same line , by means of switches incorporated in the processing circuit 64 and intended to switch the filters on and off).

For example, the signal on line 70 may indicate a compound error or a runout, depending on whether high frequency components associated with the notches, such as the signal shown between lines 56 and 58, are eliminated or not by filtering. . Each of the output lines 66 to 72 is connected to an input of several associated comparators 74, 76, 78 and 80. The other input of each of these comparators 74 to 80 is connected to a potentiometer 82 for adjusting the tolerance limits, allowing to establish the desired associated limits. Comparators 74 to 80 therefore produce signals on output lines 83, 84, 86 and 88 when the signal present on one of lines 66 to 72 exceeds the limit assigned to the corresponding comparator.

The output signals present on lines 83 to 88 are transmitted to a light display device 90 shown in FIGS. 2a and 2b. This display device or light indicator lights up indicators indicating to the operator that a particular tolerance limit has been exceeded. It is controlled by a timing and synchronization circuit 92. The processing circuit 64 includes an internal clock oscillator which can be connected by a line 94 to the timing and synchronization circuit 92 so that the two circuits 64 and 92 are controlled by the same clock circuit. A circuit 96 for selecting priority and output is connected to the light display device 90 and to the timing or synchronization circuit 92 in order to select the output signals intended for various control functions, from the signals transmitted to the device. light display 90.

The signal produced by the amplifier 42 of carrier on the line 43 is also applied to a filter 98 which, itself, is connected to a processing circuit 100 of type B. The filter 98 also transmits a signal to a circuit 102 type C treatment or a different type from those of processing circuits 64 and 100. The filter 98 is intended to eliminate the DC component of the signal transmitted to the processing circuits 100 and 102, so that the latter can produce their respective output signals. For example, the processing circuit 100 produces, on its output line 104, a signal representing either the maximum tooth-to-tooth action, or a notch. The output signal present on a line 106 represents the average tooth-to-tooth rolling action. The output signal present on a line 108 represents the difference in amplitude between the notch signal and the average tooth-to-tooth signal (this difference in amplitude being positive or negative depending on the polarity). The signal present on a line 110 represents the difference in amplitude between the notch signal and a predetermined value (this difference in amplitude can be positive or negative depending on the polarity), the predetermined value can be obtained by adjusting a potentiometer connected to a DC power source, as shown for potentiometer 578 in fig. 9.

As previously, the output signals present on lines 104 to 110 are each transmitted to one, associated, of several comparators 112, 114, 116 and 118. Each of these comparators also includes an input connected to a potentiometer for adjusting the limits of tolerance and an associated voltage source, so that an output signal appears on each of the respective lines 120, 122, 124 and 126 when the tolerance limits established by the potentiometer 82 are exceeded. The signals present on lines 120 to 126 are also transmitted to the light display device 90. The signal produced by the processing circuit 102 on a line 128 represents the partial runout. This line is connected to an input of a comparator 130, the other input of which is controlled by the potentiometer 82 for adjusting the tolerance limits. The output line 132 of the comparator 130 is connected to the light display device 90.

In the embodiment such as that shown in Figs. 1 and 3, several processing circuits or processors of the same type, such as the processors 64, 160 and 162, are shown as being made up of the same type of circuit. The invention can be implemented as shown or, alternatively, a processing circuit of a certain type can be used and controlled with switches, in a conventional manner, so that it can be interconnected. This is the case for processor 64 in the first case, and for processor 160 or 162 in another case. If separate processors are used, the processor used at all times must transmit the clock signal by its output line 94 to the timing and synchronization circuit 92.

The basic assembly of the toothed wheel 20 to be checked and of the model toothed wheel, shown in fig. 3, is the same as that shown in FIG. 1, except that different model wheels can be used. For example, the model wheel 134 is produced so as to mesh with the toothed wheel 20 to be checked along the head circle 136 of the teeth of this wheel 20. The output signal from the differential transformer 138 represents, in this case, the complex variation the distance between the axis of the model wheel and the center of the head circle of the controlled wheel. The different transformer output signal5

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rentiel 138 is transmitted to the carrier amplifier 140 by the line 143. The primary voltage of the differential transformer 138 is supplied by the amplifier 140 by means of the line 142. As previously, although FIG. 3 shows a differential transformer and a separate carrier amplifier, it is obvious to those skilled in the art that it is possible to use in the circuit of FIG. 3, by implementing conventional switching techniques, the same differential transformer and the same carrier amplifier as those used to carry out the measurements by means of the part of the machine shown in FIG. 1.

The complex waveform 144 present on line 141 and shown in FIG. 3 varies with respect to line 46 and the spacing between the reference axis 0 and line 146 represents the average dimension of the head circle of the toothed wheel. A second toothed wheel model 148 meshes with the toothed wheel 20 following the foot circle 150 of the latter. The signal produced by a differential transformer 152 is transmitted by a line 157 to a carrier amplifier 154 which, in turn, applies a control signal by a line 156 to the primary winding of the differential transformer 152. The waveform 156 present on line 155 varies with respect to line 158, and the spacing between the reference line 0 and line 158 represents the average dimension of the foot circle of the toothed wheel 20. Due to the concentricity and the errors apart, the complex signal formed by waveforms 144 and 156 is almost sinusoidal, the peaks and valleys representing the largest and smallest values of radii respectively. To measure these values relative to a reference point, the differential transformer and the carrier amplifier used produce bipolar output signals, so that the mass constitutes a reference level corresponding to the useful radius of a toothed wheel of dimension medium with no involute error.

The signals produced by the carrier amplifiers 140 and 152 represent the mean deviations of the head and foot circles and they are transmitted to processing circuits 160 and 162 of type A. As previously, the timing circuit 92 and synchronization can receive by a line 94 a clock signal coming from the processor during operation. The processors 160 and 162 include memories intended to memorize the received signals, so that the same control station can be used to measure at the same time deviations on the head circle and on the foot circle, if this is desired.

The processor 160 applies an output signal to a line 164 which represents the average useful thickness of a tooth, or the average dimension of the toothed wheel 20, measured on the circle 136 of the head of the teeth of this wheel. The processor 162 applies an output signal to a line 166 which represents the average useful thickness of a tooth or the average dimension of the toothed wheel 20 measured on the foot circle 150. The signal from the carrier amplifier 140 is shown to be of positive polarity, while the signal from the carrier amplifier 154 is shown to be of negative polarity. These signals are processed by processors 160 and 162 and they are applied to a weighted subtraction circuit 168 (these waveforms 144 and 158 can in fact be of any polarity when controlling a particular toothed wheel). The circuit 168 realizes the difference between the amplitudes of the signals present on the lines 164 and 166 and it applies to an output line 170 a signal indicating the direction of the involute error, the amplitude of this signal being proportional to the average magnitude of the tooth profile error.

The subtraction circuit 168 can be a conventional weighted subtractor circuit and it is designed to perform a weighted subtraction so that the amplitude of the subtracted signal is multiplied by a constant which transforms this difference signal between head and foot errors into a signal representing the amplitude of the useful involute error. The weighting constant used for this purpose can be easily determined by those skilled in the art, taking into account the specifications of the toothed wheels and the position,

on the profile of a tooth, of the two contact points on which this profile error is measured. The multiplication constant is a function of the tangent of the angle of the working profile of a tooth of the toothed wheel 148, divided by the tangent of the angle of the working profile of a tooth of the toothed wheel 134.

The weighted output signal representative of the useful involute error, present on line 170, is transmitted to an input of a comparator 172, the other input of which is connected to potentiometer 82 for adjusting tolerance limits and to a source. associated voltage. The output signal emitted by comparator 172 on a line 174 therefore indicates whether the tolerance determined by the potentiometer associated with this comparator 172 has been exceeded by the error signal present on line 170.

Fig. 4 represents a part of the machine according to the invention which can be used to carry out the following measurements:

- average deviation of the pitch or helix angle

- compound variation of the pitch

- average variations in taper

- compound variation of the taper

- joint cuts

Fig. 4 is a simplified diagram of a part of the gear control machine according to the invention which can be used for the measurement of pitch and taper errors. To carry out this control, an articulated or suspended control head 176 is used. The toothed wheel model 178 is, in this case, carried by a stirrup 180 of C shape which is itself mounted in a second stirrup 182, also of shape in C. The model wheel and the toothed wheel to be checked are held in engagement by a spring 183 shown diagrammatically in FIG. 4, and they are rotated while they are in metal-to-metal contact. The suspended control head 176 is designed so that the toothed wheel 178 can pivot freely in the plane of conicity indicated by the double arrow 184, as well as in the plane of the pitch indicated by the double arrow 186. The stirrup 180 carries a block 188 which projects and which actuates the detection plunger of a differential transformer 190 with linear voltage, so that the latter produces a signal representative of the error in the taper plane. A horizontal axis 192, fixed to the stirrup 182, carries a block 194 which is in contact with the plunger of a differential transformer 196 with linear voltage so that the latter produces a signal representative of an error in the plane of the pitch. The output signal from the differential transformer 190 is applied to a carrier amplifier 198 by a line 201, this amplifier 198 applying by a line 200 a certain voltage to the primary of the differential transformer. The output of the differential transformer 196 is connected by a line 205 to an amplifier 202 of carrier which applies, by a line 204, a certain voltage to the primary winding of the differential transformer 196.

The output signal applied by the amplifier 202 on a line 203 is the complex waveform 206 whose various components are separated to constitute signals representative of particular characteristics of the toothed wheel. The average step error is indicated by the spacing between the reference line 0 and a line 208. The maximum positive step error, excluding the notches, corresponding to the waveform 206 is indicated by l spacing between reference line 0 and line 210 (if waveform 206 has an average negative step error, line 210 should be drawn to indicate the smallest negative step error, excluding notch signals, of this waveform). The pitch variation error is indicated by the spacing between lines 212 and 214, this spacing representing the distance between the maximum and minimum values of the complex waveform 206, the high frequency components being eliminated by filtering. .

The detection of a notch on the toothed wheel 20, during the control carried out by means of the machine shown in FIG. 4, shows a signal such as that shown, this signal varying between lines 216 and 218 and being called signal of suspended notches. A line 220 represents the lowest positive step error for waveform 206 (if the mean step deviation was

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negative instead of positive, this line would indicate the largest negative step error). In the case of the control machine shown in fig. 4, the tooth to tooth action is represented by the spacing of the lines 220 and 222. The signal consisting of pitch error, which takes account of the notches in suspension, is indicated by the spacing of the lines 218 and 220.

The output signal of the carrier amplifier 202 is transmitted directly to a processor 224 of type A. This processor processes the input signal in a manner analogous to that in which the signal is processed by the processor 64, so that the output signal present on a line 226 represents the maximum positive or minimum negative deviation of the step. The output signal present on a line 228 represents the average step error. The output signal present on a line 230 represents the variation of the step or the compound error of the step. The signal on line 232 represents the smallest positive error or the largest negative error of the step.

The output signal of the carrier amplifier 202 is also applied to a filter 233 which is a DC filter suppressing the medium-sized signal component, so that the highest frequencies, for example those of action signals tooth to tooth and notches, are transmitted to processor 236 which is a type B processor. This processor 236 produces, on an output line 238, a signal representing the suspended notch or the tip action tooth to tooth . The signal present on an output line 240 of the processor 236 is the average tooth-to-tooth signal in suspension. An output line 242 carries the peak signal due to a signal of suspended notches having a level higher than that of the average signal tooth to tooth. The output line 244 carries a signal representative of a suspended notch or a tooth-to-tooth action greater than a predetermined value, this value being able to be established in a conventional manner by adjusting a potentiometer connected to a source d 'DC voltage supply.

The carrier amplifier 198, which receives the taper plane signal from the differential transformer 190, produces, on line 199, a signal transmitted to a processor 246 of type A. This processor 246 processes the signal which it receives in order to produce, on a line 248, an output signal representing the maximum positive or minimum negative taper error. An output line 250 transmits a signal proportional to the variation in taper or to the error composed of taper. The signal on an output line 252 represents the average taper error. An output line 254 carries a signal representing the minimum positive error or the maximum negative conicity error. As previously, it is possible to use, if desired, a group of signals similar to those described above and produced by processors 64 and 100.

The output signal of the carrier amplifier 198 is represented by the complex waveform 256 on line 199. This waveform shows that the mean taper error is represented by the spacing between line 258 and the reference line 0. The taper variation signal is represented by the spacing of the lines 260 and 262, this spacing being a function of the complex waveform 256 whose high frequency components are eliminated by filtering. The tooth-to-tooth action, detected in the taper plane, is represented by the spacing of lines 264 and 266. The error signal composed of taper, representing the maximum excursion of the complex waveform 256, is represented by the distance between lines 268 and 270. The maximum negative or minimum positive taper is represented by the spacing of line 268 and reference line 0.

Optionally, it is sometimes desired to obtain a signal representative of the weighted sum of the pitch and taper errors, the weighting factor being able to be established beforehand according to the desired goal. To this end, the output line 228 of the processor 224 applies the average step error signal to a first input of a weighted summing circuit 272 whose other input receives the signal present on the output line 252 of the processor. 246, this signal representing the average error of taper of the toothed wheel being checked.

All the output lines 226 to 232, 238 to 244 and 248 to 254, as well as the output line 274 of the summing circuit 272, are connected to associated comparators 276 which function as described previously for the comparators 74 to 80,112 to 118,130 and 172, so as to transmit a signal to the light display device 90 when the input signal present on the active line coming from a processor exceeds the signal transmitted by the associated potentiometer 82 for adjusting the tolerance limits.

Partial error processors, such as the processor shown at 102 in FIG. 1, can be added to the processing circuit shown in fig. 4, if desired.

The internal circuit of the carrier amplifiers 42,140,154,198 and 202 is shown in the diagram in FIG. 5. Each of these amplifiers comprises a power oscillator 278 which is also preferably equipped with an automatic gain control which can be incorporated in a manner well known to those skilled in the art. This oscillator produces a high frequency and low voltage signal, and its output impedance is preferably low. For example, an effective 2.5 V AC signal with a frequency of 5000 Hz is suitable for most linear voltage differential transformer transducers. This signal is transmitted by an output line 280 to the primary winding of a differential transformer with linear voltage, for example the transformer 40. The output signal from the latter is taken from the secondary winding and transmitted by a line 282 to a demodulation circuit 284 forming part of the carrier amplifier and capable of carrying out demodulation by diodes or any other suitable type of demodulation. An output line 286 of the demodulation stage is connected to the inversion input terminal 292 of a differential amplifier, while a line 288, also coming from the demodulation stage, is connected to the terminal 296 direct input from this amplifier. The difference between the signals present on lines 286 and 288 represents the displacement of the differential transformer sensor with respect to a zero or zero point.

The output terminal 294 of the differential amplifier 290 is connected to two drop resistors 298 and 300, themselves connected to one another by one end. The other end of the resistor 298 is connected to the base 302 of an NPN transistor 304, while the other end of the resistor 300 is connected to the base 306 of a PNP transistor 308. A bias resistor 310 of base is mounted between base 302 of transistor 304 and a positive terminal 312 of the voltage supply. A base bias resistor 314 is connected by one end to the base 306 of the transistor 308 and by its other end to a negative terminal 316 of a voltage supply source. A resistor 318, mounted between terminal 312 and the collector 320 of transistor 304, constitutes the collector load resistance for this transistor. A resistor 322, mounted between terminal 316 and the collector 324 of transistor 308, constitutes the collector load resistance for this transistor.

An output load resistor 326 delivers the output signal which is applied to a line 328 also referenced AL. A reaction resistor 330 is connected to the summing point 332 of the amplifier. The summing point 332 is the point at which the emitter 334 of transistor 304 and the emitter 336 of transistor 308 are connected to each other and to load resistor 326. The other end of resistor 330 is connected to terminal d inversion input 292 of the differential amplifier 290. The association of the differential amplifier 290, the transistors 304 and 308, the corresponding resistors and the reaction resistor 330 therefore constitutes an operational amplifier able to receive signals of low level input at its terminals 292 and 296 and can use these signals to produce a much more powerful output signal which can vary between voltage limits established by the power sources connected to terminals 312 and 316.

Type A processors, for example processors 64,160, 162,224 and 246, use the circuit shown in detail in fig. 6. The

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input signal present on a line 338 is applied to a filter 340 which is associated with three selection switches 342, 344 and 346. Only one of these switches is closed at a given time, and the signal associated with the chosen circuit appears across a load resistor 348. When the switch 342 is closed, the input signal present on line 338 is transmitted directly to line 350,

without modification. When the switch 344 is closed, it switches on a capacitor 352 which blocks the DC component of the input signal, so that only the AC components pass. When the switch 346 is closed, the low-pass filter, constituted by resistors 354 and 356 and by capacitors 358 and 360, is switched on. In this case, the wavy components of the input signal are attenuated. These components are of any frequency greater than 10 Hz in the embodiment described. These signals are representative of the tooth-to-tooth rolling action and the notches.

A device for successive approximations realizing a detection function and a storage function for the input signals consists of two analog circuits comprising a regressive counter 362, a progressive counter 364, a digital-analog converter 366 connected to the regressive counter 362, and a digital-analog converter 368 connected to the progressive counter 364. A positive supply voltage is applied to the converters 366 and 368 by a terminal 370, and a negative supply voltage is also applied to them by a terminal 372. The signal d the input from the filter 340 is transmitted to a direct input terminal 374 of a comparator 376. This same signal is applied to the inversion input terminal 378 of a comparator 380. A pulse signal of periodic clock, which can be, for example, of a frequency of 200 kHz, is applied by a clock 382 to the counters 362 and 364. The counter 362 is initially set to a preset count terminated by the amplitude of a signal present on a line 396 also bearing the reference Bs. This signal positions the counter 362 at a predetermined digital count representing a more positive analog level than the most positive excursion of the input signal. The signal on line 396 positions the counter only when line 384, which also has the reference Bx, also receives a signal. The counter 362 is initially positioned for each new toothed wheel to be controlled by the machine. The digital-analog converter 366 transforms the initial count of the counter 362 into an analog signal which is more positive than the maximum excursion of positive polarity of the input signal. When the clock 382 produces pulses, the counter 362 counts down to a coded value representative of a zero analog signal level as defined by the particular digital coding scheme used. When the counter 362 counts down to this coded zero count, the voltage, transformed by the digital-analog converter and applied to the output line 386, is also reduced. The output voltage of the converter 366 can change polarity if the counter 362 continues to count down after reaching its coded zero count.

The regressive counter 362 includes an internal input gate (not shown) controlled by the output signal emitted by the amplifier 376 on line 388 and by the clock 382 (similar internal gates are contained in the other counters of the machine according to the invention). This door is open until the input signal applied to the inversion terminal 374 of the comparator 376 is equal to the output signal of the converter 366. At this time, the internal door closes and the regressive counter stops its counting, so as to apply a constant signal to the output line 386. Thus, when the counter 362 is counted down and during the application of an inverted input signal to the comparator 376, the converter 366 retains the least negative or most positive excursion of the input signal, depending on the polarity of this signal.

In an analogous manner, the counter 364 is initially positioned at a coded count representing a more negative level than the most negative excursion of the input signal which, in the embodiment described, is the negative part of the most positive. The initial setting of the counter 364 is also controlled by signals present on lines 384 and 396. The digital-analog converter 368 is connected to the progressive counter 364 in order to decode the count and to apply a signal to a line 390. exit. The input of counter 364 receives the signal produced by comparator 380 on an output line 392. The counter 364 performs a progressive counting up to a coded count representative of a zero analog level, so that the output voltage applied to the line 390 by the converter 368 approaches a zero analog level when the counter 364 continues to sound. counting. As before, the polarity of the output signal from the converter 368 can change if the counter 364 continues to count beyond the coded zero count. When the output signal present on line 390 is equal to the input signal applied to terminal 378, the internal door (not shown) of the progressive counter 364 closes and the output of converter 368 applies to line 390 a signal representing the input voltage at this point. Thus, the converter 368 retains the most negative or the least positive excursion of the input signal, depending on the polarity of the latter. A line 394, which also carries the reference BR and which is connected to the two counters 362 and 364, transmits a validation signal to these counters.

The signal present on the output line 386 of the converter 366 is transmitted by an inverting amplifier 398 and an input resistance 400 to an inversion input terminal 402 of a summing circuit 404. The output signal, present on line 390 coming from digital-analog converter 368, is transmitted by an inverting amplifier 406 and an input resistance 408 to a line 410 leading to the inversion input terminal of a amplifier 424 forming part of a summing circuit 412. A resistor 414, mounted between an output line 416 and the inversion input terminal 402 of an amplifier 418, constitutes the reaction resistance of the summing circuit 404. Similarly, a resistor 420 is mounted between an output line 422 and the input terminal 410 of the amplifier 424. The output line 416 also carries the reference Av, while the output line 422 also carries the reference Au- The output line 386 is also directly connected, via the resistor 426, to the input terminal 410 of the summing circuit 412. Likewise, the output line 390 is connected by a resistor 428 to the input line 402 of the summing circuit 404.

The output signal present on line 422 therefore represents the average spacing with respect to zero. When the switch 342 is closed, its output signal can therefore alternately represent the average useful thickness of a tooth, the maximum dimension,

the average step error or the average taper error, depending on that of the processing circuits 64, 160, 16, 224 and 246 of type A which is considered and according to the position of the switches 342, 344 and 346. When the switch 346 is closed for processor 64, the output signal present on line 422 represents the average dimension of the toothed wheel rather than the average useful thickness of the tooth. However, the average pitch and taper errors can still be obtained on this line by means of processors 224 and 246.

When switch 342 is closed, the output signal on line 416 represents the peak-to-peak variation of the input signal. For the various processors of type A indicated, this line can therefore represent the error composed of center distance or the error composed of steps or even the error composed of taper. On the other hand, when the switch 346 is closed, this line represents the runout rather than the error made up of center distance for the processor 64. However, the variations of pitch and taper can still be obtained on this line for the processors 224 and 246.

A direct output line 430, also bearing the reference Bp, is connected to the output line 386. Thus, when the switch 342 is closed, this line carries a peak signal which represents the most positive or the least negative variation of the input signal. Line 430 can therefore carry, for the various processors, a signal representing the maximum useful thickness of the tooth or the positive error

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maximum (or minimum negative) of steps, or the maximum positive (or minimum negative) taper error. When the switch 346 is closed, the line 430 can carry a signal representing the maximum dimension of the toothed wheel, this signal being intended for the processor 64.

Similarly, an output line 432, which also has the reference BH, is connected to the output line 390. When the switch 342 is closed, this output line 432 represents the lowest trough of the signal or, in other words, the most negative or the least positive excursion. The signal present on line 432 can therefore represent the minimum useful thickness of the tooth, or the minimum positive (or maximum negative) error of pitch, or even the minimum positive (or maximum negative) error of taper. When the switch 346 is closed, the signal present on line 432 represents the minimum dimension of the toothed wheel instead of the minimum useful thickness of the tooth, this signal being intended for processor 64. However, the signal present on this line also also represents the minimum positive or maximum negative pitch and taper errors for processors 224 and 246. Closing switch 344 provides output signals whose DC component is removed by filtering.

The type B processor circuit, such as processors 100 and 236, is shown in fig. 7. The waveforms appearing at the various points of the circuit of fig. 7 are shown in FIG. 8. The input signal present on a line 440 of a type B processor first passes through a high-pass filter 234 constituted by capacitors 444 and 446 and by resistors 448 and 450. The output of the filter 234 is connected to an inverting amplifier 452, the output signal of which is applied to two sampling and holding circuits 454 and 456. The high pass filter 234 attenuates relatively low frequencies. Consequently, only the high frequencies, representative of the tooth-to-tooth action and of the notches, pass through this filter. Circuit 454 samples and stores the positive peaks of the input signal, while circuit 456 samples and stores the negative peaks of the input signal.

The output of the sampling and holding circuit is connected by a resistor 458 to the inversion input 460 of a summing circuit 462. Another resistor 464 is connected to the input of the sampling and holding circuit in order to transmit a second signal, coming from the filter 234, by the input line 460 to the inversion input terminal of the amplifier. summation 462. A diode 466, having a characteristic breaking voltage and preferably consisting of a Zener diode, is mounted between the input line 460 and the output line 468 of an amplifier 470 used in the circuit 462 summons. The Zener diode 466 performs an output blocking so that a pulse present on the output line 468 passes from a level close to ground to a positive level and remains at this level until the signal of input drops below a predetermined level when the sum of the input current signals passing through resistors 458 and 464 exceeds a predetermined level. Waveform 472 of FIG. 8 shows the signal appearing on the output line 468.

The input signal appearing on the input lines 474 and 475 of the sampling and holding circuits 454 and 456 has roughly a sinusoidal waveform due to the errors in the spacing of the teeth. This input signal, applied to the inverting amplifier 452, corresponds to the waveform 476 of FIG. 8. The sampling and holding circuit 454 is designed so as to memorize the positive alternation of the inverted waveform 476 and, consequently, the waveform 478 is obtained on the output line 480. The waveform 472 appears correspondingly on the output line 468, connected to an input of an AND gate 556, in order to allow the sampling and holding circuit 454 to follow the input signal until its most positive level. The sampling and holding circuit 456 produces a signal on an output line 482, this signal being transmitted, by the input resistance 484 and by the line 486, to the direct input terminal of an amplifier 490 making part of a summing circuit 488. The sampling and holding circuit 456 therefore follows the input signal to its most negative level. The blocking diode of the summing circuit 488 is a Zener diode 492.

The input current from the amplifier 452 also passes through a resistor 494 before arriving at the direct input terminal of the amplifier 490. The output signal appearing on line 496 of the summing circuit 488 therefore presents waveform 498 of FIG. 8, while the waveform appearing on the output line 482 of the sampling and holding circuit 456 is waveform 500. The output of amplifier 452 is also connected to a line 502 by the via a resistor 504 and, via an input line 506, to the inverting input terminal of a zero-crossing detector 508, intended to detect the zero-crossing of the waveform of input 476. At the instant of this passage, the signal present on the output line 510 of the detection amplifier 508 changes level. A blocking diode 512 produces output pulses on line 510, as indicated by waveform 514 in FIG. 8.

One end of a resistor 518 is connected to a terminal 520, itself connected to the positive terminal of a voltage supply source. The anode of a diode 522 is connected to the junction of the other end of the resistor 518 and the anode of a diode 516. The cathode of the diode 522 is connected to the anode of another diode 524 and to a first terminal of a capacitor 526, the other terminal of which is grounded. The cathode of diode 524 is connected to one end of a resistor 528 and to the base 530 of an NPN transistor 532 whose collector 534 is connected to a resistor 536, itself connected to terminal 520. The emitter 538 of transistor 532 is connected to a load resistor 540 and to the base 542 of another NPN transistor 544.

By connecting the emitter 538 of transistor 532 to the base 542 of transistor 544 in the manner described, a significant gain in current can be obtained. The load resistor 546 of transistor 544 is connected to terminal 520 and the emitter 548 of this transistor 544 is grounded. Thus, when the waveform 514, present at terminal 510, is at ground level, the anode of diode 516 is substantially grounded and this results in a decrease in the potential applied to base 530, at point that transistor 532 blocks. A positive voltage therefore appears on the collector 550 of the transistor 544. However, when the waveform 514 appearing on the output terminal 510 passes to a positive level, the diode 516 is placed in reverse polarization, which allows the base 530 of transistor 532 to reach a sufficiently high positive potential (after a predetermined time) so that the current passing through base 542 reaches a value causing the saturation of the transistor.

The signal present on the output line 510 of the amplifier 508 is transmitted by the line 511 to an input terminal of an AND gate 552, the other input terminal of which is connected by a line 551 to the collector 550 of the transistor 544. Thus, when the waveform 514 initially goes to a positive level, at the output terminal 510, positive voltage signals are present at the two input terminals of the gate 552, due to the base of RC time constituted by the capacitor 526 and the resistance of the associated circuit. The output signal from the collector 550 is therefore at a positive level for only a short duration, determined by the time base RC. Waveform 554 represents the output signal of gate 552 and it appears that the two inputs of gate 552 are at a positive level or 1 only until the capacitor 526 is sufficiently charged to give to transistor 544 a state of saturation. The output of gate 552 is connected by a line 553 to an input terminal of each of the gates 556 and 558. The other input of gate 556 is mounted so as to receive the signal from the circuit output line 468 462 summation, while the other input of the gate 558 is mounted so as to receive the signal present on the output line 496 of the circuit 488 summation. The output of gate 556 is connected by a line 557 to the sampling and holding circuit 454 in order to transmit a periodic repositioning pulse each time the input waveform 476 passes through zero in

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varying between a positive voltage and a negative voltage. The gate 558 applies in the same way, via a line 559, a repositioning pulse to the sampling and holding circuit 456.

The sampling and holding circuits 454 and 456 are connected, respectively by resistors 560 and 562, to the inverting input terminals of amplifiers 564 and 566, respectively. The amplifier 564, like most of the amplifiers described herein, may include an external remote gain control resistor, for example the adjustable resistor 568, if desired. The output of amplifier 566 is connected by a resistor 570 to the inversion input terminal of amplifier 564 whose output signal therefore represents the addition of the inverse of waveform 478 and waveform 500. Therefore, the peak-to-peak waveform appearing on the output line 573 of amplifier 564 is shown at 574 in FIG. 8. This waveform 574, which is of positive polarity, is applied to the direct input of an amplifier 576, the gain of which can be adjusted by means of a potentiometer 578 connected to a positive terminal 580 for supplying voltage. The signal present on the output line 577 of the amplifier 576 can represent a peak-to-peak value greater than the average signal, or a peak-to-peak value greater than a value determined by the setting of a switch 590.

The switch 590 is shown while it is positioned so as to transmit the voltage from the potentiometer slider 578 to a line 592 connected to the inverting input terminal of the amplifier 576. However, if desired, the switch 590 can also be connected to a contact 594, in which case the output signal present on line 588 represents a maximum peak-to-peak signal rather than the maximum peak-to-peak signal greater than the value established by the setting of potentiometer 578 when the switch 590 is connected to contact 596. When the switch is placed on contact 596, a line 597 carries a limited average signal and, when the switch is placed on contact 598, a maximum peak-to-peak signal greater than and greater than the average value appears on line 588, as described in more detail below.

A regressor 584 has a number of input lines 600, 602, 604 and 606. Lines 600, 602 and 604 correspond, respectively, to lines 384, 394 and 396 of counter 362. Line 606 is line d 'clock signal input. The comparator 582, the regressive counter 584 and the digital-analog converter 586 operate in the same way as the memory circuits described above with reference to FIG. 6. However, in this case, the regressive counter 584 is initially set to a code representative of an analog level more positive than the most positive excursion of the signal present on the line 588. When the signal of the output line 588 is equal to the input signal of line 579 connected to the direct input terminal of amplifier 582, the counter 584 is inhibited so as to block any counting and the signal present on the output line 588 of converter 586 represents therefore a peak-to-peak value. The signal present on the output line 588 can therefore represent a maximum peak-to-peak value or a maximum peak-to-peak value greater than an average, or even a maximum peak-to-peak value greater than a determined value, depending on the mode of use. of the circuit which depends on the positioning of switch 590.

To produce an average voltage which can be compared to the maximum peak-to-peak voltage applied to the input of the amplifier 576, the output of the input amplifier 452 is connected to an absolute value circuit 608 which includes resistors 610 and diodes 612, 614, as well as an amplifier 616. The output line 618 of amplifier 616 is connected to the anode of diode 612 and to the cathode of diode 614. The absolute value signal coming from the circuit 608 is applied to the inverting input terminal of an amplifier 620 which, itself, is connected to an integration circuit formed by a resistor 624 and a capacitor 626. The output signal from the amplifier 620 takes the form of wave 651 of absolute value shown in FIG. 8. Additional damping to produce the waveform 653 appearing at the output of the amplifier 620 can be achieved by the optional mounting of a capacitor 655 in parallel with a reaction resistor 657. The output of the integration circuit comprising the resistor 624 and the capacitor 626 is connected by an input resistor 628 to an amplifier 630 which may include a reaction resistor 631 intended for adjusting the gain, if desired. The assembly formed by the resistor 624, the capacitor 626 and the amplifier 630 constitutes a circuit which, by virtue of its integration properties, produces on the output line 633 of the amplifier 630 a signal representing the unlimited average value of the input signal from amplifier 452. This output signal takes line 632 and is transmitted to a circuit 634 which samples and maintains the average value and which correspondingly produces, on line 599, a signal representing this value.

An optional summing and limiting circuit 637 can be used to limit to a maximum the average value stored in the sampling and holding circuit 634. This circuit includes an amplifier 636, a blocking diode 638 and a potentiometer 640 which is connected to a negative voltage supply terminal 642 and, by its cursor, to a terminal of an input resistance 644, the other of which terminal is connected to the output of amplifier 630 and to an input resistor 646. This amplifier 636 produces a signal consisting of limitation or repositioning pulses, this signal being transmitted to the trigger terminal of circuit 634 of sampling and holding in order to achieve the desired limitation of the average signal.

To carry out a weighted summation of the error signals composed of pitch and taper (fig. 4), these signals are transmitted by lines 228 and 252 (fig. 10) to circuits 652 and 654 of absolute value forming part of the circuit 272 of weighted summation. The outputs of these amplifiers are connected to diode anodes 660 and 662. The absolute value circuits 652 and 654 operate as described above for the absolute value circuit 608, but with an output signal of reverse polarity. The outputs of amplifiers 656 and 658 are connected by adjustable resistors 664 and 666, respectively, as well as by resistors 668 and 670, respectively, to the inverting input terminal of an amplifier 672. The input resistors and the amplifier 672 therefore form a summing circuit 674 which produces, on line 170, an input signal representing an error composed of steps and taper which is therefore corrected by a weighting factor, so that one or the other of these error signals may have a higher weight, as desired, depending on the setting of resistors 664 and 666. It is obvious that the circuit 168 of weighted subtraction shown in FIG. 3 can be produced in an analogous manner and that any one of the various signals produced in the control machine according to the invention can be combined (or memorized, then combined) in subtraction or summation circuits, weighted or not weighted, if desired.

The processor 102 of type C is shown in more detail in FIG. 9. The input of this processor is connected to a line 678 via a low-pass filter 680 consisting of resistors 682 and 684 and capacitors 686 and 688. The output of the filter 680 is connected by a line 685 to the inversion input terminal of an operational amplifier 690, the output of which is connected by a capacitor 692 and a resistor 694 to a line 698 terminating in a circuit 696 for comparison by means of the input terminal d inversion of an amplifier 700. The capacitor 692 blocks the DC component of the compound signal in order to prevent the component corresponding to the size of the gear wheel from affecting the signals processed by this circuit. The signal passing through the resistor 694 is also returned by a feedback resistor 697 to the direct input terminal of the amplifier 690. The capacitor 692 is also connected to an integration circuit 702 comprising resistors 704 and 706 and capacitors 708 and 710. The function of this integrator is to effect a phase shift of approximately 90 ° relative to the signal appearing at the input terminal 698. This phase-shifted signal is transmitted by a line 712 to the direct input terminal of an amplifier 714. A resis5

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The reaction resistance 716 can preferably be adjusted in order to establish the correct 90 ° phase shift, and a stabilization resistor 718 is mounted between the inversion input terminal 720 and the ground.

The phase shifted output signal from the amplifier 714 is transmitted by a resistor 722 and a line 724 to the inversion input terminal of the comparison circuit 696, the output of which therefore produces a signal representing a comparison between the signals of phase-shifted and phase-shifted compound errors, the high-frequency components being eliminated from these signals. The comparison signal is used to detect the amplitude of the partial deviation of the runout error corresponding to each sector of 90 ° of relative rotation of the model and controlled toothed wheels. If desired, it is obviously possible to use phase shifts other than 90 °.

The output of the circuit 696 for comparison is connected to a circuit 726 of absolute value which is produced in the same way as the circuits of absolute value 652 and 654 of FIG. 10. The signal is then transmitted by an inverting amplifier 728, comprising an optional gain adjustment resistor 730, and by a resistor 732, to the direct input terminal of an amplifier 734 which is connected to a regressive counter. 736, itself being connected to a digital-analog converter 738. The assembly formed by the amplifier 734, the regressive counter 736 and the digital-analog converter 738 operates as described above for the circuits of successive approximations also using regressive counters. The input lines 740, 742, 744 and 746 of the regressive counter 735 correspond to the input lines 600, 602, 604 and 606, respectively, of the regressive counter 584.

The regressive counter 736 is initially positioned at a coded account representing a more positive analog level than the most positive excursion of the signal coming from the amplifier 728. This counter 736 performs a countdown and the digital-analog converter 738 transforms this account into a corresponding analog voltage until the signal present on the output line 128 of the converter 738 is equal to the input signal present on a line 750 terminating at the direct input terminal of the amplifier 734. When these two signals are equal, the internal gate of the regressive counter is inhibited and the voltage established by the converter 738 and the output line 128 represents the maximum partial deviation for the chosen phase shift.

Due to inaccuracies or manufacturing defects, a toothed wheel can have a pitch circle perfectly concentric to the axis or to the mounting hole, while groups of teeth have differences in thickness only near the head. In a planetary gear with a floating gear ring, these imperfections cause variations in the angular speed of the associated gear, which can shorten the useful life of the gear and cause the generation of noise. This is the reason why it may be desired to equip the gearwheel control machine according to the invention with an additional circuit intended to detect the component of angular speed or runout presented by the head circle of the teeth. a gear wheel.

The runout of the head circle of the controlled wheel 20 is represented by the spacing of the lines 145 and 147 on the waveform 144

of fig. 3, this waveform representing the variation of the detected signal and from which the high frequency components are eliminated. This signal is processed by processor 160 which produces a runout signal on line 161, in the same way as processor 64 produces a corresponding runout signal on line 70. Line 161 is connected to an input of a comparator 173, the other input of which is connected to a potentiometer 82 for adjusting limits, so that an output signal is transmitted on line 175 transmitted to the light display device 90 when the limit associated with this comparator is exceeded.

The successive approximation circuits described above are produced in the same way as conventional analog-digital converters of successive approximations. In a conventional analog-to-digital converter, an analog level of relatively constant value is applied to one input of the comparison circuit and a second analog signal, decoded from the count of a digital counter, is applied to the other input of the circuit for comparison. The counter then counts from zero to this constant level, and stops counting when the two analog signals are equal. The digital value of the counter is then used as an output signal.

The machine uses a circuit of successive approximations in a completely different way. The successive approximation circuits of the machine according to the invention are not intended to produce a digital signal corresponding to a relatively constant analog input signal, but they are used as elements for detecting peaks and valleys of analog signals and as storage elements for these values until the use of these is necessary. This avoids the disadvantages of short-term storage due to a discharge occurring in conventional analog storage circuits when the signal must be stored for relatively long periods, for example during a complete revolution of a room or a gear wheel to control. The circuit of successive approximations is therefore not used for a conventional analog-digital conversion, but for the detection of the maximum and minimum levels of an analog signal and for the permanent storage of these levels (until the latter are requested by external equipment).

All the reaction resistors of the operational amplifiers which have not been mentioned above bear the reference 800 in the figures, and all the diodes of the absolute value circuits which have not been cited above bear the reference 802. During the operation of the counters of the successive approximation circuit, these counters can, for example, contain twelve bits and all the bits of a regressive counter can be set at a level 1, while all the bits of a progressive counter can be set at a level 0. The account representative of a zero analog output voltage therefore appears when all the stages of the counter are placed at level 1, except the stage of the most significant bit.

It is clear that the machine can not only be used for complete control gear wheels, but also for circular or rectilinear tooth segments.

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Claims (16)

643,654 2 1. Machine for controlling a toothed wheel (26), characterized in that it comprises a model toothed wheel (20) meshed with the wheel to be controlled so that, during their common gear rotation, it is possible to move the axis of one relative to the axis of the other in a chosen direction of movement, each time an irregularity makes such a displacement necessary while maintaining a close engagement contact, a sensor (40, 42; 138, 140; 152,154; 190,198; 196,202) providing a control signal representative of the relative displacement of one axis with respect to the other, this signal having a maximum amplitude excursion in the chosen direction, with respect to a reference level, when relative displacement occurs, and a device for successive approximations comprising a comparison element (376) mounted so as to receive the control signal, a counting element (362) initially placed at a representative account of '' a signal level known lower, in the chosen direction, at the maximum amplitude excursion, the counting element being designed so as to periodically count down until its count is representative of a signal level which is close to L excursion of maximum amplitude and a digital-analog converter (366) connected to the counting element in order to transform the count made by the latter into an analog level, the output of this converter being connected to the comparison element, the output is itself connected to the counting element in order to stop the operation performed by the latter when the control signal is of a level equal to that represented by the account established in the counting element. 2. Machine according to claim 1, wherein the control signal has a first excursion of a maximum amplitude in the chosen direction and a second excursion of maximum amplitude in a direction opposite to the chosen direction, relative to the reference level , when the relative displacement occurs, characterized in that the device for successive approximations comprises a second comparison element (380) which is mounted so as to receive the control signal, a second counting element (364) initially placed at a count representative of a greater signal level, in the opposite direction, than the second excursion of maximum amplitude, the second counting element being designed so as to periodically count down until its count is representative of '' a signal level which is close to the maximum amplitude excursion in this opposite direction and a second digital to analog converter (368) connected to the cond counting element in order to transform the account produced in the latter into a second analog level, the output of the second converter being connected to the second comparison element whose output is itself connected to the second counting element in order to stop the operation performed by the latter when the control signal is of a level equal to the level represented by the account established in the second counting element. 3. Machine according to claim 2, characterized in that it comprises a device combining a first level of signal stored by the first converter (366) and a second level of signal stored by the second converter (368), the first and second levels representing maximum excursions of the control signal. 4. Machine according to claim 1, characterized in that it comprises a second successive approximation device (224), in that the first successive approximation device (246) detects and stores a first signal level, in that that the second successive approximation device detects and stores a second signal level, the first and second levels representing maximum excursions of the control signals supplied by sensors (190,196) sensitive to relative displacements of the axes in different directions (184,186 ), and in that it comprises a device (272) combining the first and second signal levels. 5. Machine according to claim 1, characterized in that it comprises a phase shift device (702) intended to shift by a predetermined value the phase of the control signal, which is periodic when the toothed wheels turn, a subtraction element , mounted so as to receive the phase shifted control signal (696) and the phase control signal in order to realize the difference between these two signals, an absolute value circuit (726) connected to the subtraction element and producing a signal of absolute value representative of the absolute value of the difference thus obtained, and a second successive approximation device intended to detect a maximum excursion of the signal of absolute value during an angular rotation of the toothed wheels, this rotation being approximately equal to the number of degrees of phase shift produced by said phase shift device. 6. Machine according to claim 1, characterized in that it comprises a circuit processing the control signal, which is periodic when the wheels turn, and comprising a high-pass filter (234), which eliminates the low frequencies and the component continuous control signal to produce a high frequency periodic input signal having a maximum positive deviation and a maximum negative deviation from a reference level during each rotation of the wheels, a first analog memory (454) for storing the maximum positive excursion of each cycle of the input signal, a second analog memory (456) for storing the maximum negative excursion of each cycle of the input signal, a device (488) for combining the excursions positive and negative maximum values, stored in a single polarity signal for each cycle of the input signal, a device for resetting to the initial position (556, 558) the analog memories é both connected to the first and second memories and receiving said input signal in order to reset the memories during each cycle of the input signal, and a successive approximation device mounted so as to receive said single polarity signal so detecting and storing a maximum excursion of this single polarity signal during each cycle of the input signal. 7. Machine according to one of claims 1, 2 or 6, characterized in that it also comprises a support designed to allow relative movement of the toothed wheels in a plane perpendicular to their axes. 8. Machine according to one of claims 1,2 or 6, characterized in that it comprises a support designed to allow relative movement of the toothed wheels in the plane of their pitch. 9. Machine according to one of claims 1,2 or 6, characterized in that it comprises a support designed to allow relative movement of the toothed wheels in the plane of their taper. 10. Machine according to one of claims 1, 2, 5 or 6, characterized in that it comprises an absolute value circuit (608) which processes the control signal and which transmits it, in the form of a signal of determined and unique polarity, to the element of comparison. 11. Machine according to one of claims 1,2, 5 or 6, characterized in that the control signal is of single polarity. 12. Machine according to one of the preceding claims, characterized in that the sensor comprises a differential amplifier comprising an inversion input terminal and a direct input terminal, two complementary transistors (304, 308) connected by their transmitters and the bases of which are connected to the output of the differential amplifier, the collector-emitter circuits being connected in series with a power source applying a positive voltage to one terminal and a negative voltage to the other terminal, a resistance of feedback (330) being connected at one end to the transmitters and at its other end to the inverting input terminal of the differential amplifier. 13. Machine according to one of the preceding claims, characterized in that the sensor comprises a single detection element (38) and in that it comprises several signal processing circuits (64,100,102) intended to simultaneously process the control signal supplied by the sensor and to produce output signals representative of various components of the control signal, these cir5 10 15 20 25 30 35 40 45 50 55 60 65 3 643,654 processing circuits each comprising a successive approximation device intended to detect maximum excursions of the respective input signals relative to a reference level, filters which can be selectively circuited between the sensor and the processing circuits, in order to selectively filtering the control signal, which is periodic when the wheels are spinning, to obtain its components of different frequencies and selectively transmitting them to at least one of the processing circuits. 14. Machine according to one of the preceding claims, characterized in that one of said processing circuits comprises a filter (340) which can be selectively switched on between the sensor and the device for successive approximations in order to filter the control signal , which is periodic when the wheels turn, selectively assuming the function of a filter for blocking the DC component or that of a low-pass filter. 15. Machine according to one of the preceding claims, characterized in that the sensor comprises an element (284) intended to demodulate the control signal when a carrier excites the sensor. 16. Machine according to one of the preceding claims, characterized in that said relative movement authorized between the axes is a rotational movement. Electronic machines for controlling or testing gears are known, the efficiency of which depends on a precise adjustment of the speed of the control motor used to control a pinion or a toothed wheel, control at during which a model or standard gear is engaged with the gear or pinion under test. Gear control machines are also known which use demodulation and filtering of division error signals (tooth to tooth error) from the compound error signal, the filtering and demodulation being carried out under conditions dependent on the weather. A gear control machine using analog memory has been designed to eliminate problems and lacks in precision due to demodulation and time-dependent filtering techniques, as described in the United States patent. No. 3851398. However, this gear control machine requires two detection devices and two analog memories. One of the memories is repositioned after each revolution and, therefore, it is associated with the compound error made on the wheel under test. The other analog memory is repositioned by the signal from the other detector and it represents the division error associated with each tooth. The use of two detectors and two mutually associated memories can introduce, into a gear control machine, a lack of precision appreciably greater than that resulting from a detection of all the error signals by means of independent sensors. The gear control machine according to the invention is designed not only to eliminate the problems posed by demodulation and filtering devices as a function of time, but also to produce various other types of error signals associated with toothed wheels. , with the high precision that can be obtained by using independent sensors and permanent memories.