DE1196285B - Control device for alternating rapid excitation of one electromagnetically actuated friction clutch and brake - Google Patents

Description

Control device for alternating rapid rain, one each electromagnetically actuatable friction clutch and brake The invention relates to a control device for alternating rapid rain, one each acting electromagnetically on a common load actuatable friction clutch and friction brake, with a signal generating device to generate an input signal that can be set to two different signal values, by the alternating excitation of the arranged in separate output circuits Excitation windings of the friction clutch and the friction brake can be controlled.

The invention is based on the object of a successive Activation of the clutch and brake in one working cycle, with can be repeated extremely quickly.

A control device of the type mentioned at the beginning has already become known, with their help alternately an electromagnetically actuated friction clutch and a brake are energized, the alternating energization by opening and closing of contacts is effected. The excitation voltage is known in this case Control device a chopped DC voltage, and this device has .den Disadvantage that switching off a coil only in the interval between two square waves can take place. In addition, due to the inductance of the excitation coil increases the ignition of the thyratron used in the device, the excitation voltage is proportionate slowly, so that the intervention of the brake or clutch is delayed accordingly he follows. This known device is therefore limited to uses in which a relatively high switching inertia can be accepted. The present invention, however, relates to a control device that is extremely enables rapid switching from the clutch to the brake and vice versa.

It has also become known a control device that a Has differentiator. It is a function of the Speed of an internal combustion engine operating control device with a capacitor as a differentiator, with the help of which in a relay coil one of the frequency of the Voltage surges of the ignition distributor of the internal combustion engine generates proportional current will. As a result, the relay speaks at a certain frequency of the voltage surges and thus at a predetermined engine speed. The trained according to the invention Although the control device also has a differentiating element, it has has another object than the differentiator of the above-mentioned known ones Control device. In the subject matter of the invention, the differentiating element generates an intermediate signal with a predetermined waveform, while the capacitor of the known control device serves as a charging capacitor, on which one of the frequency of the incoming pulses approximately proportional tension builds up.

The object on which the invention is based is avoided the above-mentioned disadvantages according to the invention by a control device solved by a timing device for measuring successive periods is characterized, each of which is divided into a first and a second sub-period is divided, and the one signal generating device for generating a rectangular input signal having a first value during the one partial period and during the other partial period has a second different value; moreover is according to the invention a differentiating network for receiving and converting the input signal Provided in an intermediate signal which rises steeply during the first partial period a first extreme value increases and then gradually, preferably exponentially, drops to a first intermediate value, and that during the second Partial period changes steeply to a second extreme value and then gradually, preferably decreases exponentially to a second intermediate value, the intermediate signal according to the invention for controlling the to change the mean speed of the Load by quickly starting and stopping the load serving reciprocal Excitation of the excitation windings of the friction clutch and the friction brake during the first and second partial period is used and where through the extreme values of the intermediate signal the respective corresponding excitation coil over the in continuous operation permissible excitation is overexcited beyond.

The control device designed according to the invention expediently has a phase reversal device, which at the output of the differentiating network, which has at least one RC element, is arranged and by means of the intermediate signal a first and a second control signal can be derived which are phase-shifted to one another, but are of essentially the same curve shape and their curve shape is the curve shape of the intermediate signal corresponds or is similar, the circuit also being made in this way is that by means of the first control signal, the excitation of one output circuit and the excitation of the second output circuit can be controlled by means of the second control signal is.

All details about the invention emerge from the following Description in conjunction with the drawing, on which an embodiment of a according to the invention designed control device is shown and explained. in the individual FIG. 1 shows a longitudinal section through the center of a device according to the invention controllable clutch and brake in partial view, F i g. 2 is a circuit diagram of a control device designed according to the invention, FIG. 3 to 10 curves, which Show voltages or currents at different points on the control device, where the abscissa forms the time axis and the curves are plotted as whether there is a common abscissa axis everywhere. acts, F i g. 11 a cathode ray oscillogram the control pulse and the speed of the driven shaft.

The invention relates to the optional supply of two electromagnetic windings 10 and 11, which enable the transmission of torque to an output, such as. B. a rotatably mounted shaft 12, control. The windings 10, 11 (FIG. 1) are parts of an electromagnetic clutch 13 which, when switched on, transmits a drive torque to the shaft, and an electromagnetic brake 14 which exerts a deceleration torque on the shaft.

The illustrated coupling 13 acts directly on a drive part fastened to an uninterrupted rotating shaft 15 of the motor 16. This part has cylindrical rings 17 made of magnetizable material, which are arranged radially at a distance from one another and which are connected to one another by non-magnetizable spacer parts 18 and have axially directed pole faces 19 at one of their ends on a plane. These pole faces can axially engage with a flat magnetic armature ring 20 bridging them, which forms the driven coupling part and is arranged on the output shaft 12 to be movable in the axial direction but non-rotatable relative to it.

The clutch winding 10 is mounted in a fixedly arranged toroidal core 21 made of magnetizable material with a U-shaped cross-section, which has legs 22 radially spaced apart from one another and which fit precisely over the outer ends of the pole rings 17 . When the winding is powered, the resulting magnetic flux runs around the core, radially between the legs 22 and the pole rings and axially back and forth between the pole faces 19 and the armature, as in FIG. 1 is shown with 23 dashed lines. Such magnetic flux pulls the armature into tight engagement with the pole faces, thereby coupling the output shaft 12 to the drive shaft 15.

In a similar way, the brake 14 has a directly attractive effect and has a an annular fixed magnetic core 24 of U-shaped cross-section, which the winding 11 surrounds and radially spaced pole pieces which end in axial pole faces 25. These are held by a flat magnet armature 26 bridged and can get into engagement with this armature, which on the output shaft 12 is not rotatable, but is arranged to be axially displaceable. at When the winding 11 is fed, the resulting magnetic flux runs between the pole faces and brings the armature into engagement with this, creating a retarding Torque acts on the output shaft.

On the basis of the invention, it is possible to have the clutch 13 and the brake 14 become effective in quick succession in order to set the output shaft 12 in rotation or to stop it extremely quickly. The shaft 12 is accelerated from a standstill to the speed of the drive shaft 15, after which a complete stop takes place, the entire process taking place in a few milliseconds. This is achieved by means of a novel electronic control system which, in response to a single pulse 27 (Fig. 3), feeds windings 10 and 11 in rapid succession, eliminating the need for switch contacts or other moving parts and the inherent time losses in their operation and delays no longer apply. The control first divides the pulse into two components 28 and 29 (FIGS. 5, 6), which are spaced apart from one another at a time equal to the duration of the pulse. The first component 28 occurs at the beginning of the pulse and is used to feed the clutch 13. The second component 29 is used to feed the brake winding 11 at the end of the pulse. Simultaneous engagement of the clutch and brake is avoided by switching off or de-energizing each winding before the other winding is supplied.

In order to obtain the successive coupling and braking components 28 and 29 from the individual control pulse 27, the control pulse according to FIG. 2 initially fed to a differentiating circuit 30. This converts the pulse into an alternating signal with two half waves 31 and 32 (FIG. 4). The first of these half-waves increases at the beginning of the pulse 27 in the positive direction to a high amplitude and then decreases. The second half-wave 32 also increases and decreases in amplitude, but in a negative direction as a result of the termination of the pulse.

The alternating signal 31, 32 is fed from the differentiating circuit 30 to an amplifying and phase-reversing part 33. The output from this contains two alternating signals 34 and 35 (FIGS. 5 and 6), one in phase and the other not in phase with the signal 31, 32 originating from the differentiating circuit. The coupling component 28 is the positive half-wave of the in-phase signal and the braking component 29, the positive half-wave of the signal 35 of reversed phase, which originate from the phase-reversing part. From there, the respective components are applied individually to the windings 10 and 11 via separate electronic amplifier devices 36 and 37 .

Thanks to the extraordinarily rapid action, the improved control system is particularly suitable for operation in rapid change, ie starting and stopping the output shaft 12 by means of a series of rapidly recurring control pulses 27. Such an input signal for the device can be supplied in various known ways, z. B. by a conventional square wave generator 38 of suitable frequency (Fig. 2). With such a generator, the duration and the time interval between successive pulses depends on the selected output frequency. In order to feed the successive pulses to the differentiating circuit 30 , the latter is connected to the generator via a suitable coupling capacitor 39 and a resistor 40, which are connected in series with one another.

The differentiating circuit 30 in this case contains a variable resistor and a variable capacitor connected in parallel. The corresponding plates of three capacitors 41, which are connected with one pole by a common conductor 42 to the coupling resistor 40, while the other poles are individually connected to fixed contacts of a selector switch 43 , serve as the variable capacitor. These contacts can be brought into contact individually with an adjustable contact 44. The variable resistor consists of a fixed resistor 45, one terminal of which is connected to the common conductor 42 of the capacitors and the other terminal of which is connected to one end of a variable resistor 46. The sliding contact 47 of this latter is directly connected to the adjustable selector switch contact 44. The output signal 31, 32 of this circuit then appears as the voltage between the sliding contact 47 and a conductor 48 connected to the other terminal of the variable resistor 46.

Due to the resistors and capacitors 41, 45 and 46 arranged in parallel, the output signal of the half-waves 31 and 32 at the differentiating circuit initially suddenly rises to a sharp peak 49 (FIG. 4) and then falls exponentially. The value to which each half-wave drops before the next half-wave depends on the selected values of the resistors and capacitors. For a reason explained later, it is desirable that each half-cycle decay exponentially to a value 50 well above zero and then eventually rapidly to zero at the end of the half-cycle, as in FIG. 4 is shown.

The part 33 used for phase reversal contains a triode, the anode 51 of which is connected to the positive terminal of a direct current source 53 via a resistor 52. To complete the anode circuit, the cathode 54 is connected to the negative terminal of the power source via two series-connected cathode resistors 55 and 56 and to earth. The output signal from the differentiating circuit is fed to the phase-reversing part by connecting the sliding contact 47 of the adjustable resistor 46 to the grid 57 of the triode via a series resistor 58 and the output conductor 48 of the differentiating circuit to the connection 59 between the cathode resistors 55 and 56. The potential at this connection is in phase with the output signal of the differentiating circuit and supplies the coupling component 28. The braking component 29 is obtained from the anode 51 of the triode.

While transistors can also be used as electronic control devices 36 and 37 for amplifying the individual control components 28 and 29 and for supplying them to the corresponding windings 10 and 11, pentodes are used in this case. The cathodes 60 of these tubes are connected to each other and to earth, and the anodes 61 are individually connected to the positive terminal of another direct current source 62 via windings 10 and 11. To complete the corresponding anode circuits, the negative terminal of this power source is connected to the cathodes via earth. The braking grids 63 of the tubes are connected directly to the cathodes, and the screen grids 64 are connected to the cathodes via a capacitor 65 and to the positive terminal of the current source 62 via a resistor 66.

The various components 28 and 29 pass from the anode 51 of the phase inverter 33 and the junction 59 of the cathode resistors 55 and 56 to the corresponding control grids 67 of the pentodes 36 and 37 via coupling capacitors 68 and individual resistors 69 connected in series with the grids If no signals are fed into the phase reversing device, the pentodes are not conductive or blocked, so that the current through the windings 10 and 11 is essentially switched off since the control grids are biased negatively with respect to the cathodes 60. For this purpose, an adjustable tap 70 of a resistor 71 connected in series with another direct current source 72 is connected to an adjustable tap 73 of another resistor 74, which in turn lies between the ends of the grid resistors 69 that are not on grids and across two resistors 75 which are connected to earth with a common connection 76. In the case of an electromagnet of the type mentioned, the breakdown and build-up of the magnetic flux in the magnetizable parts takes place with a slight delay after the supply circuit for the magnet winding is closed and interrupted. These delays are due to the hysteresis and eddy current effects in the magnet parts and can be reduced without damaging the magnet by briefly supplying the winding with a voltage that is several times the nominal voltage. Such overexcitation is brought about according to the present circuit by utilizing the shape of the various components 28 and 29 and bringing the amplitude of these into a certain ratio to the values of the voltages applied to the grids 67 and the anodes 61 of the pentodes 36 and 37 can be created. Thus, the voltage of the current source 62 supplying the anode current is a multiple of the nominal voltage of each of the windings 10 and 11, and the bias voltage applied to each grid is set such that when the tip of the corresponding component is superimposed on it, essentially the entire anode voltage is applied to the winding will. Then, when the amplitude of the component drops from its peak value, the voltage across the winding quickly drops to a value below the nominal voltage.

By suitable shaping, the clutch and brake components 28 and 29 are also used to reduce the flux in the magnetizable parts of the coupling 13 'and the brake 14 to the lowest possible value in order to enable the simultaneous transmission of a torque by both devices which become effective through friction avoid and at the same time ensure that the coupling parts do not slip with respect to one another before the end of the control pulse 27 and that the brake quickly brings the output shaft to a standstill. For this reason, the parts of the differentiating circuit cause the voltage of each half-cycle 31 and 32 to drop exponentially to the value 50 above zero before it suddenly drops to zero at the end of the half-cycle. The value of the voltage applied to the clutch or brake winding 10 or 11 , which corresponds to these values of the half-wave, is below the nominal voltage, but above zero.

In connection with the following discussion of the operation of the control device according to the invention is to be noted that the time base of all Curves according to FIG. 3 through 10, represented by the vertical lines 78 is the same for all. For operation it is assumed that there is no input signal from the square wave generator 38 and that the pentodes 36 and 37 by the grid voltage are locked. Then both the clutch winding and the brake winding 11 not fed, and the output shaft 12 is at a standstill.

At the beginning of the first control pulse 27 (FIG. 3), the output voltage at the differentiating circuit 30, which is represented by the curve 31, 32 (FIG. 4), suddenly rises to the peak 49. This voltage then drops exponentially to the value 50 and quickly drops to zero at the end of the pulse. The positive half-wave 31 generated in this way is amplified by the phase reversing device 33 in order to form the clutch component 28 (FIG. 6), which is fed to the control grid 67 of the clutch pentode 36; it outweighs the negative bias, which makes the tube conductive. The resulting voltage across this grid is represented by curve 79 (FIG. 7). It suddenly rises to a peak slightly above zero and then falls exponentially to a value below zero, which, however, is above the value of the reverse voltage before suddenly falling to this voltage at the end of the half-cycle.

At the moment when the potential at grid 67 of the coupling pentode 36 initially rises above zero, essentially the entire anode voltage becomes 62 applied to the clutch winding 10. This causes a sudden increase in Current in the winding along a curve 80 (Fig. 8) from zero to a peak value 80a, which is about twice the value of the rated current for this winding amounts to. The rated current is represented by a line 81 (Fig. 8). A corresponding one The flux increases in the magnetic circuit 23 through the coupling armature 20 and pulls him quickly into full engagement with the pole faces 19. The output shaft 12 is thereby coupled to the drive shaft 15 and is quickly up to speed same accelerates.

When the voltage on the coupling grid 67 decreases below its maximum value the clutch current also decreases to a value 82, which is below the nominal value 81, but is above zero before the grid voltage suddenly occurs at the end of the first half-wave 31 of the output signal from the differentiating circuit 30 drops. This intermediate value of the current is sufficient to cause the coupling armature to slide with respect to the pole faces to be avoided and in this case amounts to about 45% of the nominal current. When rubbish of the potential of the grid 67 of the coupling pentode 36 falls below the blocking potential the anode current decreases exponentially from the intermediate value 82 to zero, as in 83 (FIG. 8) is shown. By keeping the intermediate value of the current as low as without slipping the coupling is held possible, not only is the attractive force acting on the armature rapidly decreased, but the back electromotive induced in the clutch winding Force is also kept low when the voltage drops to zero.

During the first half cycle 31 of the output signal of the differentiating Circuit 30 and while the clutch 13 is fed, the opposite adds up Signal from anode 51 of inverter 33 with normal negative bias at the control grid 67 of the brake pentode 37 and keeps the grid close to the blocking potential, as shown by curve 84 (Fig. 9). The brake winding 11 then remains turned off when the current is at zero, as shown by curve 85 (Fig. 10) will be shown. At the end of the first half-wave 31, however, the braking component 29 becomes applied to the grid, the potential of the same suddenly to one above zero lying tip 86 (Fig. 9) to increase. This results in overexcitation the brake winding essentially in the same way as with the clutch 13 during of the first half-wave 31.

At the same time that the current in the brake winding reaches its peak 87 and the resulting flux pulls the brake armature 26 into engagement with the pole faces 25 to stop the output shaft 12, the current in the clutch winding has a low value on curve 83 ( Fig. 8) is achieved, so that a simultaneous transmission of opposite torques by the clutch and the brake is essentially avoided. At the end of the braking component 29, when the potential of the grid 67 of the brake pentode 37 and thus the voltage applied to the brake winding suddenly drops to zero, the current in the winding increases exponentially from an intermediate value 88 (FIG. 10) in the same way as described with respect to clutch current. The brake is released when the clutch is engaged as a result of the first half-wave of the second control pulse 27a. In the case of successive half-waves from the differentiating circuit, i.e. when successive pulses are received after the first, the waveforms of the various voltages and currents are repeated in the form shown in FIG. 10 way shown.

In a switching device built in the manner described with a clutch 13 and a brake 14, which operate at a nominal voltage of 90 V and a nominal current of 90 mA, the initial voltage was that of the clutch winding 10 at the beginning of the control pulse 27 and the brake winding 11 on At the end of the pulse, approximately 550 V. This resulted in a current of approximately 200 mA at each peak 80a and 87 with intermediate current values 82 and 88 of approximately 40 mA and 45 n / o of the rated current, respectively. The results obtained with this device are shown in FIG. 11, wherein curves 90 and 91 are oscillograms of a control pulse and the output voltage of a tachometer generator 92 (FIG. 1), the rotor of which is driven by the output shaft 12. The pulse is one of a series that occurred at a frequency of approximately 20 Hz with a duration of 25 milliseconds each. In Fig. 11, the distance between adjacent vertical lines 93 corresponds to 2.5 milliseconds and the distance between adjacent horizontal lines 94 of the voltage curve 91 of the speedometer 360 rpm of the output shaft 12.

From Fig. 11 it can be seen that the output shaft 12 reached the full speed of the drive shaft 15, ie 1800 rpm, within a period of 1.3 milliseconds after the initial rise of the control pulse (curve 90) . The output shaft was decelerated to a standstill approximately 3.75 milliseconds after the beginning of the end of the pulse. By increasing the frequency of the pulses, it has been found that it is possible to repeat a full cycle of accelerating the output shaft to full speed and decelerating it to a complete stop over fifty times a second.

Claims (7)

Claims: 1. Control device for alternating rapid rain one electromagnetically operable friction clutch each acting on a common load and brake, with a signal generating device for generating one of two different ones Signal values adjustable input signal, through which the alternating excitation of the Friction clutch excitation windings arranged in separate output circuits and the friction brake is controllable, characterized by a timing device (38) for measuring successive periods of time, each of which is divided into a first and second partial period is divided, a signal generating device (38) for Generating a square-wave input signal, which during the one sub-period a first value and during the other partial period a second, different from it Has value, a differentiating network for receiving and converting the input signal into an intermediate signal (FIG. 4), which rises steeply during the first partial period a first extreme value (49) and then gradually, preferably exponentially, drops to a first intermediate value (31), and that during the second Partial period changes steeply to a second extreme value (99) and then gradually, preferably exponentially, decreases to a second intermediate value (32), and using the intermediate signal to control the mean speed change the load by quickly starting and stopping the load reciprocally Excitation of the excitation windings of the friction clutch and brake during the first and second partial period, wherein the extreme values of the intermediate signal corresponding excitation coil beyond the excitation permissible in continuous operation is overexcited. 2. Control device according to claim 1, characterized in that the differentiating network (30) has at least one RC element. 3. Control device according to one of claims 1 or 2, characterized in that a phase reversal device (33) is provided, which is arranged at the output of the differentiating network and by means of a first and a second control signal from the intermediate signal can be derived which are out of phase with one another, but of essentially the same The shape of the curve corresponds to the shape of the curve of the intermediate signal or similar, and furthermore the circuit is made such that by means of the first Control signal the excitation of one output circuit and by means of the second control signal the excitation of the second output circuit is controllable. 4. Control device according to Claim 3, characterized in that the phase reversal device for generating a mutual phase shift of the first and second control signals from is formed substantially 180 °. 5. Control device in which each of the two Output circuits are each assigned a current control device, each of which is one Has control electrode according to claim 3 or 4, characterized in that the Control electrode of a current control device, the first control signal and the Control electrode of the other current control device, the second control signal can be pressed is. 6. Control device according to claim 5, characterized in that the current control devices are connected in such a way that the current control device (36) of that output circuit which is controllable by means of the first control signal, during the occurrence of the first Half-wave of this control signal is essentially open and during the occurrence the second half-wave of this control signal is essentially blocked, and the Current control device of that output circuit, which by means of the second control signal controllable is, during the occurrence of the first half-wave of this control signal essentially locked and during the occurrence of the second half-wave this control signal im essential is open. 7. Control device according to claim 5 or 6, characterized in that the current control device (36) of that output circuit to which the first control signal can be fed can be opened by the leading edge of the first half-wave of this control signal and can be blocked by the trailing edge of the first half-wave of this control signal , and the current control device (3) of the other output circuit can be blocked by the leading edge of the first half-wave of this control signal and opened by the trailing edge of the first half-wave of this control signal. B. Control device according to one of claims 5 to 7, characterized in that the current control devices each have at least one electronic amplifier stage. 9. Control device according to claim 8, characterized in that the amplifiers of the two current control devices are connected to one another in push-pull circuit. 10. Control device according to one of claims 5 to 9, characterized in that the current control devices are designed such that each of them, depending on the control signal impressed on the control electrode at the beginning of the conductive phase, a very steep voltage rise at the excitation winding of the associated output circuit on its The peak voltage significantly exceeds the nominal voltage and then the voltage at the field winding steadily decreases to an intermediate value which is close to the relevant nominal voltage and which essentially maintains this intermediate value until the start of a blocking phase of the relevant current control device. Documents considered: German Patent No. 906 354; German interpretative document No. 1059 539; French Patent No. 1187 935; British Patent No. 692,203; U.S. Patent Nos. 2,630,467, 2,805,393; Book by Riehter: "Electronics", 5th edition, pp. 99, 10 (, Würzburg, 1958.