DE2128943A1 - Brake circuit for stopping a DC motor - Google Patents

Description

International Business Machines Corporation, 10504-Armonk, H * Y * Brake circuit for stopping a DC motor

The invention relates to a brake circuit for generating a Brake impulses triggered by an external brake signal to the Shutting down a DC motor with a control circuit, which was at Mo to ret ill generated an Absohaltsignal for a Bremslatpulsgenerator.

In a known brake circuit, the brake pulse begins with the brake signal and ends with the switch-off signal when the motor sum has come to a standstill. Sa is the braking effect of the brake pulse However, it is different; it is generally greater when the engine is in a cold operating state than when it is hot, for example the moment at which the motor ouch in this known circuit Standstill kocnt · depending on the operating state in which calibrated the motor was b # ia initiation of the braking processB was. '

The object of the invention is to design a circuit of the type mentioned at the beginning so that this dependency can be reduced.

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The invention let characterized in that the control circuit when a predetermined engine speed is reached, an additional provisional Äbechaltsignal supplies the brake pulse generator switches off temporarily and triggers a restart which triggers the braking pulse generator after a freewheeling period has elapsed switches on again and that the duration of the freewheeling time period at small pawn of the first braking impulse is large and vice versa "According to the invention, the braking process is in two braking phases on" between which the motor continues to run unbraked in freewheeling mode during a freewheeling period and by corresponding® The aforementioned dependency is reduced when this freewheeling period is measured. It is even possible to have this dependency to suppress completely, so that the time span from the initiation of the braking process to the shutdown of the motor is independent of the operating temperature of the engine is always the same.

A further development of the invention, which is characterized by a low scarf · » -curgsmufwand is characterized in that the Reclosing has a proportionally acting monostable flip-flop circuit which, following an input pulse, has a Output pulse with a duration proportional to the input pulse duration generated and with the trailing edge of their output pulse switches the braking pulse generator back on and that a timer is provided, which is triggered by the brake signal after Ab * - the trailing edge over a predetermined period of time of a Birigangeimpuleee for the proportional toggle switch bertiauaenänen pulse delivers and that the front edge of this input pulse is approved by the preliminary switch-off signal «

The invention and other features thereof will now be discussed with reference to explained in the attached drawing

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In the drawing shows:

Figure 1 shows the speed time diagram for one operating phase of a peer-to-peer motor,

Figure 2

Figure 3 shows the speed diagram the braking process in known BremB circuits,

a first exemplary embodiment of a brake circuit according to the invention,

FIG. 4 and FIG. 6 and FIG. 7 are diagrams to explain the function the brake circuit according to Figure 3,

a second example Brake actuation according to the invention,

Diagrams to explain the function of the circuit according to FIG. 6 and

FIG. 8 shows a diagram on the basis of which the mathematical basis for the modification the illustrated exemplary embodiments are explained -

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In Figures 1, 2, 4, 5, 7 and 8 are time velocity diagrams specified, in which the Motorgeechwirdigkeit V on a vertical axis versus time T is plotted on the horizontal axis.

Figure 1 shows a diagram of an operating phase of a DC motor, which is accelerated from standstill with the speed V = O along an acceleration device, then with his constant operating speed VB and is then braked to a standstill on a braking test. The hatched one Area is the Bretns area. The braking process will in the case of the DC motors in question here, triggered by a brake pulse that is sent to brake coils or brake drivers df.-s Motor arrives that, as long as the braking pulse lasts, braking or with one of the rotary motion of the motor Act on this torque to bring it to a standstill. The length of the braking pulse must affect the braking process be coordinated. The braking pulse must therefore end as soon as the motor has come to a standstill. The one for the implementation time required for braking is not always the same? it depends on many circumstances, in particular the operating temperature at which the engine is currently running. list the engine is cold, then it can be braked easily and the brake pulse must be short-lived. If the engine is hot, it is heavy to decelerate and the brake pulse must be "on longer duration. Brakes a motor according to the timing diagram according to FIG. 2 a with a braking pulse which has a fixed time duration Tconst, which then comes when the operating state is hot The braked motor does not come to a standstill if the duration of the braking pulseB is matched to the braking process in the cold operating state is. The speed or revolutions of the motor is monitored with a tachometer and the braking pulse is terminated if -] he tachometer shows standstill, then the engine is calibrated at the end of the braking process at a standstill, but it reaches this standstill earlier in a cold operating state than in a hot one

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Operating state, as can be seen from FIG. 2b, in which the time-speed diagram for the braking process of a tachometer-controlled braking circuit is shown. The resulting braking range difference AQ is shown hatched in Figure 2,

A corresponding braking range difference arises if the loss of speed ΔΥ "one suffers with the aid of an integrator circuit to the motor during braking, measuring and using the measurement result of the end of the braking pulse to the respective operating state is reached · adapts In this case, as in Figure 2 c apparent" where the time-speed diagram of an integrator-controlled brake circuit is shown, although the motor is at a standstill at the end of the braking state, but in a cold operating state it comes to a standstill earlier than in a hot operating state.

For many applications it is desirable that the braking process, which brings the direct current motor to a standstill, is always terminated at the same point in time, regardless of the respective operating conditions, in particular the operating temperature and circuits according to the invention allow such control.

A first embodiment of a brake circuit according to the invention is shown in Figure 3 and in Figure 4 are in the timing diagram A series of voltages is plotted when operating at the points marked with the same letters the circuit of Figure 3 occur. V is the speed of rotation of the motor to be braked, which is shown in FIG. 4 plotted over the same time axis as the voltages is.

In Figure 3, 10 denotes a bistable stop toggle circuit, at the forward output of which the braking pulse G is tapped, during the braking process to the brake driver dee not shown DC motor arrives. The stop / tilt switch is switched forwards at the moment when the run signal 4

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drops or has ended, which is fed into the brake circuit from the outside. This run signal arrives via an OR circuit 12 and an inverter 14 to a mono-stable multivibrator 16 which, at the end of the run signal, generates a switching pulse I? generated by a micro = second duration, which arrives at the forward switching input of the stop toggle circuit 10. The running signal A also arrives via an inverter 18 at a monostable reference flip-flop circuit 20, the output pulse B of which arrives at one input terminal of an AND circuit 22, the other input terminal of which is connected to the rear output terminal of the stop flip-flop circuit 10 Input connection of an OR circuit 26 and also to a monostable proportionally working flip-flop 2.4 ₅ whose output pulse D reaches the second input connection of the OR circuit 26. The output signal E of the OR circuit 26 reaches the second input connection of the OR circuit 12. "Pulse D, the duration of which is in a certain ratio to the duration of the output pulse C of the terminal circuit 22" The flip-flop. circuit 24 has for this purpose the input side a capacitance that is charged by the pulse C on a SOannungeniveau whose size depends on the time duration of the pulse C, "The time length of the output pulse D or the time duration of the domestic = · ^v ', stable phase of the flip-flop depends on the load level that has reached the capacity. The ratio of the duration of the output pulse to that of the input pulse of the proportional multivibrator is the same as the ratio of the discharge time constant to the charge time constant of said capacity _t

The stop toggle circuit 10 is controlled by output pulses H of a detector © 30, which is sent to the switching back input of the Stop toggle circuit 10 is connected, switched back

The detector circuit 30 is a tachometer circuit, the resistor included in the motor circuit

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31 stood the respective speed of the motor to be braked and in contrast to usual tachometer circuits with, everyone Braking process generates two pulses H, namely the first as soon as the rotational speed V has dropped to half the operating value 1/2 Y lat and the second pulse as soon as the motor has come to a standstill, i.e. for the speed V = O applies » The detector circuit 30 can also be set so that it is at a different predetermined intermediate value of the speed provides the first output pulse H, but in the following is aar Explanation of the puncture initially assumed clafJ the first Imouls H of the detector circuit is generated when the The speed of rotation of the motor has fallen to half the value during the braking process «

The braking process is divided into two braking phases. The first 3rema ~ phase begins with the end of the running signal A, i.e. with the output pulse the reference flip-flop 20 and ends with the end dea Output pulse B of this reference flip-flop 20 (see Figure 5) .v The second braking phase follows the first braking phase at uncl ends when the motor has come to a standstill. The F.ippseit the reference flip-flop is chosen so long that the motor bit up from every operating state during the first braking phase 1/2 V can be braked. Once this has happened, the delivers Detector circuit their first output pulse H, which is the Stoapkippkreis 10 switches back. At this moment the input pulse C for the proportionally working flip-flop 24 begins, which is ended with the end of the first braking phase, i.e. the end of the output pulse B. With the end of the input pulse C begins the output pulse D. £> ie proportionally working flip-flop is set so that the output pulse it generates D has the same length of time as the pulse C. At the end of the output pulse D, the stop trigger circuit 10 switched forward again and the braking impulse of the second braking phase begins «Since the two impulses C and D are at the same time Length, the braking pulse G of the second braking phase begins at exactly the same time after the end of the first braking phase, to that of the Br eras impuls G "09853/1196

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ended in the first braking phase before the end of the first braking phase. When the engine is cold, the braking pulse of the first braking phase ends earlier than when the engine is hot, and the braking pulse begins when the engine is cold the second braking phase later than when the engine is hot * As a result, at the end of the second braking phase, the motor comes to a standstill at time 3? 0, the time T 0 being independent of the operating temperature and other operating conditions under which the engine was working before the start of the braking process *

. ^ The brake circuit according to the invention achieves the lateral independence ^ Dependency of the end of the braking process by introducing a freewheeling phase, during which the motor rotates at half operating speed in the example just described. You can do this Free-running phase also to another point in the speed diagram so that the motor is idle during the freewheeling phase at a speed other than half the operating speed turns. For this it is only necessary to switch the detector circuit on to set this other speed with regard to the respective first pulse H · By changing the proportional working flip-flop is then, the ratio of the temporal length of pulse C to pulse D adjusted accordingly, so that the desired independence of the temporal κ position of the end T 0 of the braking process results again

In the circuit of Figure 3 it has been assumed that the freewheeling speed, here half the operating speed, is achieved in any case within the first braking phase Reference flip-flop 20 ahead of the one shown in FIG second embodiment, special precautions are also taken to prevent malfunctions in the event that the Free-running speed not within the breakover time of the reference breakover circuit 20 is reached · For the circuit from FIG. 6, voltage-time diagrams are shown in FIG. 7 in a representation corresponding to that in FIG indicated, namely in Figure 7 a for a brake

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Process with a cold engine and in Figure 7b for a braking process with a hot engine and in Figure 7c for a braking process with very hot engine. The points at which the voltages indicated in FIG. 7 occur are in FIG. 6 with the same letters as indicated in Fig. 7 is the rotational speed of the motor denoted by V in FIG. 7 and plotted over the same time axis as the voltages.

In FIG. 6, 32 denotes an oscillator which is a monostable Drives oscillator trigger circuit 34, the output pulses of which arrive at one input of an OR circuit 36. The output pulses the OR circuit 36 reach one input terminal an and circuit 38, from the output terminal the brake signal W is tapped, which arrives at the brake driver oes not shown DC motor to be braked » With 40 a bistable flip-flop is referred to, which is responsible for the first braking phase * to the forward holding input terminal the flip-flop 40 receives the run signal K, the is fed into the circuit from outside. The one ahead Output terminal of the flip-flop 40 tapped output signal Q reaches the second input connection of the OR circuit 36 and there covers the output pulses of the oscillator trigger circuit 34. The braking signal W at the output terminal of the output circuit 38 occurs when, at the same time as the output signal of the OR circuit 36, the stop toggle circuit 10 is switched forward, so the output signal S is present at the forward output. With a monostable recovery flip-flop circuit is referred to, the input side to the rear AuegangsanschluQ of the flip-flop 40 is connected and on the output side to an input terminal an OR circuit 26a is connected. The output terminal of the OR circuit 26a is interposed an inverter 28 and a monostable flip-flop 29 with .a flip-flop time of one microsecond at the forward switching Input connection of the stop toggle switch 10. The recovery toggle switch 42, in conjunction with the toggle switch 40, ensures

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that the second braking phase is initiated, even if the first braking phase lasts longer than the output signal of the reference flip-flop circuit 20 - a situation in which the monostable proportionally working flip-flop circuit 24 does not generate an output pulse. 50 denotes a delay which is connected between the output port of the switch 22 and an input port of the OR circuit 26a and introduces a short delay of one microsecond in order to avoid peak pulses at the output of the OR circuit 2 ^ a if the switching processes at the output \ rn- i εαι input of the proportionally operating flip-flop 24 coincide in time. The switching elements, which are denoted in FIG. 6 with the same reference numbers as in FIG. 3, have, unless expressly stated otherwise, the same structure and the same function as the identically numbered parts from FIG. 3.

During operation, the trailing edge of the running signal K switches the reference flip-flop 20 into its unstable switching state via the inverter 18 * The stop flip-flop 10 is _{switched forward via the OR circuit 26S 3} 4en inverter 28 and the flip-flop 29 and a braking signal W is now produced at the output terminal of the AND circuit 38 ,

When the stop toggle switch 10 is switched forward for the first time, the toggle switch 40 responsible for the braking phase is also there switched forward and the pulses from the oscillator tilt switch 34 are of the DC voltage level at the output terminal of the Toggle circuit 40 covered in the OR circuit 36 so that Brake signal W a constant continuous signal is «by the detector circuit 30, which, as explained in the text of FIG. 3, have their first output signal when half the rotational speed is reached supplies, the tilt-stop circuit is activated at the end of the first braking phase 10 und'die flip-flop 40 switched back, namely by the detector circuit 30, which thus ends the first braking phase «With the Trailing edge of the output pulse of the proportional multivibrator 24 becomes the stop toggle circuit 10 again via the OR circuit 26a, the inverter 28 and the balanced flip-flop 29

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switched forward. The output signal S of the stop toggle opens the switch 38 for the pulses of the OszillatorkiOpaehaltung 34 and a pulse-controlled brake signal is generated, am Output of the and circuit 38 for this second brake pad. By the detector circuit 30 is switched off as soon as the motor has come to a standstill is, the stop toggle switch 10 is switched back again and thus also terminates the second braking phase *

The circuit according to Fig. 3 and 6 makes it possible to determine the final storage division, in which the motor comes to a standstill, based on the run signal K by adjusting the breakdown time of the reference breakdown circuit 20 to.-Adjust. You can of course change the end position of the motor also adjust by adjusting a feeler with which the running signal is controlled, but this is the mechanical adjustment of a tactile organ and it is usually more difficult to accomplish and handle than the electronic one feasible adjustment of the flip-flop time of the reference flip-flop circuit 20.

The application of the invention is not limited to cases in which the motor to be braked is running at exactly half the speed in the phase of phase, as is the case with the described exemplary embodiments to simplify the explanation } . * and the discharge time constant of the proportional multivibrator 24 must then be adapted to the freewheeling speed. The mathematical relationships on which this is based are specified below with reference to FIG.

According to Figure 8:

^a 1

<r— is “constant

^a 2

* V

t ₁ «1/2" S ^

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V t ₀ = 1/2 a

«F - t ₁ * T - 1/2

PUr the braking offset θ applies i

+ 1/2 (1 / 2V ^ ₁ + (1 / 2V) At +

i / 2 (1 / 2V) t ₂

V V V _

«1 / 2V [3/2 (1/2 a7) + (1 + K) (T - 1/2 17) + 1/2 (1/2 IT)]

2 a

= 1/4 X. [3/2 - (1 + K) + 1/2 -Ii + 1 / 2T (I + K) T V Ή ^a 2

So that the braking offset 9 is independent of S ₁ , the following is set:

3/2 - (1 + K) + 1/2 - -

®2

K «1/2 (1 + ^)

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Claims (1)

P 15 957 May 21, 71 BOCHE 1.! Brake circuit for generating an external brake ^ - ^ signal triggered braking pulse to stop a ttleichetromnotore with a control circuit that stops when the motor is stopped and a switch-off signal for a braking pulse generator is generated, characterized in that the control circuit (30) when a predetermined engine speed is reached, an additional provisional switch-off signal which the brake pulse generator delivers (10) temporarily switches off and a restart (20, 24-) triggers after a period of idle time has elapsed the braking pulse generator (10) switches on and that the pawns the freewheeling period of time with small pawns of the first braking impulse is large and vice versa « 2 · Brake circuit according to claim 1, characterized in that the reclosing has a proportionally acting monostable multivibrator (24) which, following an input pulse (O) generates an output pulse with a duration proportional to the input pulse duration and with the return edge of your Auegangeimpuleee switch the braking pulse generator (10) back on. 10 9 8 5 3/1196 BAD P 15 957 2 1289A3 tet and that a timer (20) is provided, which of the Brake signal (A) triggered after a predetermined period of time has elapsed on the trailing edge of an input pulse for the proportional flip-flop (24) provides the determining pulse and that the gate edge of this input pulse through the preliminary switch-off signal is determined. 3 * brake circuit according to claim 1 and 2, characterized in that .. that the braking pulse generator (10) is a bistable multivibrator 'whose forward switching input connection with the interposition of a Öder circuit (12λ of an inverter (H) and a monostable flip-flop circuit (16) with a very short Kippseii to the input connection for a complementary brake signal (A) is connected to which input connection with the interposition of an inverter (18) a monostable reference tilting table · = » device (20) all timing circuits are connected whose output « proper to the brake pulse (B) of the flip-flop circuit (10) complementary Anagangesignal in an end circuit (22) to the input «- . signal of the nsfcgeschalttten proportionally acting flip-flop (24) is rounded, the output and input signal in an open OR circuit (26) linked to a second input. the srats Oderachaltung (12) is initiated and that the tax ^; circuit (30) to the switching back input of the toggle switch (10) aageaohloeeen is » 4 »Brake circuit according to one of the preceding claims, characterized by its auxiliary circuit (34, 40, 42), which occurs when of the additional preliminary switch-off signal only after the time span preset in the tent circuit (20) has elapsed Brake pulse generator switches on again. 5. Bröffisaohaltung according to any one of the preceding claims, characterized characterized in that the control circuit provides the additional provisional® Deceleration signal provides when the engine speed to the half the value of the operating speed has fallen and that the ! 09853/1196 _RAn ^. BAD ORiGiNAL P 15 957 21 289Λ3 proportionally acting flip-flop provides an output pulse of the same duration as its input pulse. 10-9 8 5 3, / 1-1 9 B ^{BAD 0RIG} * NAL Lee r soap