DE1450694A1 - Switching device for a gearbox - Google Patents

Description

(B 79 501 XIl / 47h) 24 * 5 * 1968 Rb / Κη

Robert Bosch GmbH, Stuttgart

Cater layers ,! Switching device for a gearbox

The invention relates to a switching device for a gearbox, especially for an unsynchronized motor vehicle change gearbox, with a servomotor to operate a switching element of the gearbox » during the switching process, the switching element in its neutral position is held until the gear to be engaged is synchronized is.

In the automatic or semi-automatic actuation of change gears which are equipped with a conventional mechanical synchronizing device, the time for a gear shift should not be significantly less than a second in order to ensure a sufficient service life of the synchronizing device shift times of at most a few tenths of a second are desirable »Such short shift times are possible with non-synchronized gearboxes *

In a known switching device, the switching movement of the servomotor is interrupted in each case in the idle division, and only when the two " gear parts to be shifted run synchronously, is polarized by a Relay a contact closed and the servomotor switched on again, so that it can continue to run and fully engage the gear ka ^ | u - With this switching device the duration of the holding process is extended by the fact that the

909S10 / 0400

tv; UnteilaQen (Art.? ^ V Ahs.2Nr.l SatzadeiÄnofciuMj.i,.,, ·

⁸ ORIGINAL " ² "

P H 50 694 »6 ■ · R. 8290 - '-. · ■■■.'

(B m.5Pi Xli7i? H) ^: 24.5 * 1 ^; 96β "Kb / Kn

Robert Bosch GmbH, Stuttgart ■ - '-V'

Servomotor during the switching process stopped and had a short pause is started again »This extension is undesirable and insofar also disadvantageous, because the synchronism is only available for a short time and the servomotor has to start up during this time and therefore often ■ will not be able to shift into gear in time * This may cause the transmission was easily damaged

It is an object of the invention to avoid these mowing parts »· ·· - ■

According to the invention, this is achieved with a "switching device" mentioned above; that a force storage device, in particular a spring, is opened to the servo motor and the switching element, so that there is a lock to hold the retaining element the öetriebeis provided in de £ Ineerlaufstellung and DAFL an electronic SteUereiiitiGhtung'vorgesehen is * d'ie "at the Irrexchen 'synchronism tie lock lost" Bieser Kraftsßexcheri for "B * a iPederi the EijüschaltcLäuer the SfSrre fespannfi soon as währent overall synchronism get% ti iö%, the ifferrS becomes g'elQäk;, and the connecting member is thru the im
Kraftpeiher g & stored energy immediately in legs end division # ebrä.c & t »The servomotor is niö &% more needed here * The switching is'on this
Way sstafk shortened. I can do it with a weaker servo motor
Satisfied ', since the amount of money to be paid for the maximum duration is less than in the case of the known tariffs · ■

According to a further feature of the invention, a particularly simple structure of the switching device is obtained in that, in a manner known per se, with
the transmission input - a first voltage generator "and with 'the * transmission output

.BADORiQJNAl

H50694

PU 50 694.6 (B 79 501 XIl / 47fa) Robert Bosch GmbH, Stuttgart

R. 8290 24.5 * 1968

a second voltage generator is connected is't _} each of which is one of
generate their drive speed dependent voltage, their outputs bit are connected to a device for voltage comparison, and that this device sit the lock is in operative connection.

The device for voltage comparison is advantageously designed in such a way that the voltage generators are parts of an in particular four-branch bridge circuit and in each case in one of two via a first node in series
lying bridge branches that there are resistors in the third and fourth bridge branches connected in series via a second node and that at least one voltage-dependent switch is provided, the input of which is connected to the first and second node »

Further details and expedient developments of the invention are described and explained in more detail below on the basis of exemplary embodiments.

Show it

1 shows a simplified representation of the transmission in connection
with the various control units,

Fig. 2 is a plan view of the arrangement for actuating the
Switching element according to Fig. 1,

Fig. 3 and 4 details of Fig. 2,.

Figures 5 to 7 are a schematic representation of various
Phases of a holding process,

8 shows the circuit diagram of an electronic control unit,
FIG. 9 shows a circuit variant of FIG. 8,

9098 10/0400

BAD ORJGiNAL

-4- U50894

: (B-79 501 XIl / 47h) "24.5 * 1968 Bb / Κη

Robert Bosch GmbH, Stuttgart

The embodiment of a switching device shown in FIGS. 1-4 is used to operate one with an electrically operated clutch 11 provided unsynchronized motor vehicle gearbox 12 with H-Sehaltschema for four forward gears 1-4 and one reverse gear R, accordingly The stop scheme has a backdrop of 15. Shift lanes 14 »in which a switching element in the form of a switching lever 15 is guided. The operation can be done fully automatically or by preselecting a corresponding gear.

To transfer switching movements to the shift lever 15, it is on one end of a push rod. 16 articulated, the other end articulated with a crank 17 is connected, which via a reduction gear 18 of a reversible motor 19 can be set in motion. The radius the crank 17 · corresponds to about half the switching path between two each other opposite gear positions of the shift lever 15 · To the one associated with it To give the end of the push rod 16 a certain form of movement, a slide bearing 20 guiding the push rod 16 is arranged between the crank 17 and the gate 13. In addition, the push rod 16 is flexible designed so that the movement generated by the crank 17 is adapted to the movements of the shift lever 15 guided in the shift gates 14 becomes ο. ".-.," =

A leaf spring is used as the push rod 16, one end of which is over an elastic member designed as a double spring 23 and serving as an energy store is connected to the shift lever 15.

9098 10/0400 -

³ ~ V 'BATH

(B 79 501 XIl / 47h) May 24, 1968 Rb / Κη

Robert Bosch GmbH »Stuttgart

So that the shift gate for reverse gear R while driving forward remains locked, is on the backdrop IJ a pivot point 24 by means a pivoting motor 25 pivoting gate plate in two end positions (Fig · 5) provided »the two contiguous recesses 2?» 28 has. The recess 27 has the shape of a rectangle with through the end positions of the shift lever 7 in cLen chords 1 to 4 given limitations5 the off * Savings 28 has the shape of the shift gate from 1st gear to reverse gear R, Depending on the position of the link plate 26, there is only one switching to the forward * « or only possible between 1 · gear and reverse gear. With a gearbox With only four gears (three forward gears and one reverse gear) in the Η diagram, this gate plate 26 is omitted.

A lock is also provided, the details of which are shown in FIGS are shown. It is used to control the shift lever 15 during the switching process to hold in the neutral position of the transmission, that is, the crossbar of the H and consists of a lever 32 rotatable about a fixed joint 31, the has passed at one end with a fork 33 comprising the shift lever 15 and at its other end carries a roller 34 which is in a detent a rotatably mounted locking lever 36 (Fig. 2) can intervene, dex through a tension spring 37 is pulled into its rest position and by an electromagnet 38 can be brought into its detent position. The electromagnet 38 serves at the same time as a locking element and - together with the tension spring 37 - as a release device «

The change gear 12 is from an internal combustion engine, not shown driven, the suction pipe 4I of which can be actuated by servomotors 42 »43

so9aW / 04öd '' "■

PH 50 694 * 6 ^; R. 82QO ■

(B 7? 501 .Χΐΐ / 47 ^) 5/24/1968 Rb / iöi ..

Bobert Bosch GmbH, Stuttgart, \. ■. ^J _? . ,,. ·.

Throttle valve 44 (Fig. I) contains, and is connected to the internal combustion engine via the transmission drive shaft 45. The transmission 12 is connected to the drive wheels of a vehicle (not shown) via its output shaft 46 : ■■■ - -.-. = ■ ·. ■

With the drive shaft 45 is coupled 47 ^e i ⁿ the first Tac3iag ".4 & eaeicätor and to the output shaft 46 via gears 49, a second tachometer generator through gears. Both supply speed-dependent voltages, which are fed to a control device 55 via ^{lines 5 1 »52, shown in simplified form in FIG.} In addition, a selection device 57 is provided, which is bordered by dash-dotted lines in FIG. 8 and which is used to select the desired song. It contains further switching elements, not shown, which, together with limit switches (also not shown), determine the direction of rotation of the reversible motor 19 and actuate the clutch at the beginning of the switching process. Control lines go from the selector 57 and the control unit 55 58 to 62 to the safety clutch 11, to the electromagnet 58 * to the swivel motor 25 and to the servomotors 42 and 45 «

8 shows the structure of the control device. The two tacho generators 48, 50 are connected to one another via a first node 65. You can _: Eg »as green current tacho generators or as brushless alternating current. Generators with the following rectification: and smoothing, ·, -The latter version has the advantage ,, / that no brushes, exchangeable About a second node 66 connected resistors 67, 68 a (in the

(B 79 501 XIl / 4710 Robert Bosch GmbH, Stuttgart

R. 8290
May 24, 1968 Rb / Κη

Drawing highlighted by thick line lines) four-branch bridge circuit. They also "form a further four-branch bridge circuit with two resistors 70,? 1 connected to one another via a third junction 69. The" two bridges are matched differently so that the second and third junction each have different potentials. As an example, in the illustrated position of the selector device 57 (1st gear) with the clutch 11 engaged, the voltages TL and ΐΓ _{? Generated by the tachometer generators 48 and 50 may?} be the same size. The resistance 70 is then as great, for example, "2000 0hm how resistance 7I» s ° ctaß & ^er third node 69, the same potential as serving as the reference potential ers-th node 65th

The resistor 67, on the other hand, is somewhat smaller (e.g. 1800 ohms) than the resistor 68 (e.g. 2000 ohms), so that the second node 66 is opposite to the first node 65 has a negative potential »

The first node 65 is connected to the positive terminal 72 of a battery 73 ″, whose negative pole 74 is connected to ground. The potential "of the positive pole 72 serves as reference potential zero.

A first trigger amplifier 77 with two pnp transistors 7 ⁸ , 79 is connected to the first and second nodes 65 and 66 (outlined in the drawing with dash-dotted lines), and a second trigger amplifier 80 is connected to the first and third nodes 65 and 69 with two pnp transistors 78 ', 79 * connected, the output of which with a one

909810 / 04QO

Cb 79 5or-xii / q? Hl -.- -, _a 24 * 5.1968.

Robert Boseh GmbH, Stuttgart

pnp transistor containing phase inverter 81 is connected, $ in OR-? · Link "" 8.5 with two oppositely directed diodes 98 and 103 is connected to the Outputs of the first flip-flop amplifier 77 and the phase inverter 81 connected. Its output is connected via line 59 to the electromagnet of the locking and releasing device. '

The selection device 57 contains a voltage divider consisting of four resistors 86 to 89 and connected in parallel to the generator 50. The connection points of these resistors are with four contacts of a choice- '

■ switch 90 connected, corresponding to the associated gears with 1 - 4 are designated. Between the positive line 72 and the one with the switching arm 9I of the changeover switch connected to the output line connected to the resistor 7I 92 is the voltage tL · '. By suitable choice of the resistors 86

', up to 89, in the "synchronism of the gearbox in the associated gear, the ratio of Ü_ * to" U ^ "is identical in each case, ie these resistances are graduated according to the various gear reductions. The output of switch "90" is connected to resistors 68 and % t ;

The two trigger amplifiers 7, 7 and 80 have the same structure. It is therefore sufficient to describe the first trigger amplifier 77; the same reference numerals, with a reference line, are used for the second tilt amplifier. The base of the input transistor 78 is connected to the second node 66, and the base of the input transistor 78 ′ is connected to the third node 69. The emitter of the transistor 78 (78 ') is connected to the plus line 72, while its collector is connected to the minus line via a resistor 93 (95 ^f )

(B 79 501 XII / 47h) May 24, 1968

Robert Bosch GmbH, Stuttgart

and a resistor 94 (94 ¹ ) is connected to the base of the transistor 79 (79 ^! ), which in turn is connected via a resistor 95 (95 ') to the positive line 72, to which the emitter of the transistor 79 (79) is also connected. ) is · Its collector is connected via a collector resistor 96 (96 ») to the negative line 74 and via a feedback resistor 97 (97 ') Mi * & βτ base of the input ^{transistor 78 (78 1} ). In addition, the collector of the transistor 79 is connected via the control line 61 to the servomotor 42 and to the anode of the diode 98 belonging to the OR element 85, the cathode of which is connected to the control line 59 with a resistor 99 * umL connected to the common negative line .

The collector of the transistor 79 ^r is connected via a resistor 100 to the base of the transistor 82, which is connected via a resistor 101 to the positive line 72 to which the emitter of the transistor 82 is also connected. A collector resistor 102 connects the collector of the transistor 82 to the negative line 74. In addition, the control line 62 and the anode of the diode 105 belonging to the OR gate 83 are connected to this collector. The cathode of diode 103 is connected to the cathode of diode 98 »

The change-speed transmission described in FIGS. 1 * 8 operates as follows 1

If in ferry operation with clutch 11 engaged, first forward gear, as shown in Fig. β is inserted, the second node 66 has a negative potential with respect to the positive line 72. The base of the transistor So 78 is negative with respect to the emitter, i.e. transistor 78 is conductive. Its collector therefore has a potential that is only slightly smaller than that

§09810 / 0400

- 10 -

PH 50 694 »6 - · 'Η · ⁸² 9 °

(B 79 50t XIl / 47h) . May 24, 1966 Sfc / Κη _r ~

Robert Bosch GmbH, Stuttgart

the positive line 72. This potential is also applied to the base of the transistor 79 _{via the resistors 94 9 95 and keeps this transistor blocked} is connected to ground.

The third node G $ has in this ferry service as explained the potential of zero, so the potential of the positive line 72 d _o h. the transistor 78 * is non-conductive and its collector potential is almost as negative as that of the mimic line 74 · The ^{base of the transistor 79 * also receives a negative potential via the resistors 94 * un <} ^ 95 ', ie this transistor becomes conductive «Its collector, therefore has a potential which is only slightly smaller than that of the positive line 72, and this potential is passed through the feedback resistor 97 ^! also to the base of input transistor 78 ';

■ s' ■

transmitted and keeps it blocked »In addition, this potential is also transmitted to the base of transistor 82 _{via resistors 10O 9 101 and blocks it.} So it acts as a phase reversal stage. The control line 62 can therefore also not carry any current. The control line 59 is also currentless, since the anodes of the two diodes 98, 103 practically have the potential of the negative line. Consequently, the servomotor 43 and the. Electromagnet 58 not actuated.

If the selector switch 90 is now from its position 1 (1st song) into the Position 2 (2nd gear) brought, which can be done either by hand or by a corresponding, For example, automatic depending on the accelerator pedal position and driving speed can take place, then first the clutch 11, for example

9 0 981 0/040 0

«11 m

U50694

P 14 5 © 694.6 Β 829Q

(B 79 501 | gl / 47h) : ■ 24 * 5 <t968. Eb / Κη

Robert Bosch GmbH, Stuttgart

Via an auxiliary relay (not shown), switched off and reversible Motor 19'BO switched on so that it rotates clockwise with reference to FIG (see Pig. 5-7). The switching elements required for this are because for the present invention without meaning, not shown »The present invention can also be used with a gearbox, for example, without further ado, which has several shift levers and thus several servomotors for the different gears *

By switching the switch 90, the potential of the nodes 66 and 69 has changed abruptly into the negative, since the speeds, with which the tachometer generators 48 and 50 are driven, initially not change significantly »

In the case of the first trigger amplifier 77, this does not change anything _s since its input transistor 78 is already conductive. In the case of the second trigger amplifier 80, on the other hand, the input transistor 78 'changes from the non-conductive to the conductive state, since its base becomes negative with respect to the emitter. This gives its collector a potential that is only slightly more negative than that of the plus things «| device 72 and also the base potential of the transistor 79 * is - via the resistors 95 * and 94 ¹ - practically zero, ie the "transistor 79 ¹ is blocked and its collector potential becomes strongly negative. Via the feedback resistor 97 'the base of the Input transistor 78 'is still further controlled to negative, i.e. amplifier 80 "flips". Correspondingly, the base of phase-reversing transistor 82 also becomes negative (via resistors 100 and iOi) a control current flows "

90 98 10/040 0.

-i 12 -

P 14 50 694.6 · R. 829Q

(B 79 501 XIl / 47h) May 24th I968 Rb / Κη

Robert Bosch GmbH »Stuttgart%

The design of the amplifiers 77 and 80 as tilting amplifiers has the effect of in the transition from the conductive to the non-conductive state and vice versa a "; low thermal load on the transistors, which increases operational reliability compared to a simple DC voltage amplifier - which is also used could be - will be significantly improved.

The current flowing in the control line 62 actuates the servomotor 43, which in turn closes the throttle valve 44. In addition, the actuating element of a brake (not shown) can be connected to the line 62, which brakes the engine when upshifting and thus enables the tractive force to be interrupted for a shorter period of time when changing gears. The current in the control line 59 actuates the electromagnet 38, which now seeks to ziibringen the locking lever 36 against the action of the tension spring 37 i ⁿ its lock division. '

Pig. 5 shows the transmission mechanics at the beginning of the shifting process, in which the crank 17 rotates clockwise. As soon as the crank after a quarter ι rotation reaches the position shown in FIG. 6, the roller 34 engages into the notch 55 of the locking lever 36 and holds the switch via the fork 33 ; lever 15 in the idle position. Since the motor I9 continues to run, the serving as a force storage double spring 23 biased and stores the from Motor I9 supplied energy. The recess 27 of the gate plate 26 prevents that the shift lever I5 in the shift channel for the reverse gear R comes. ν

9098ΐα / 0400

"' ^: - 13- H50694

(B 79 5Qi XLl / ATh) ... .... 24 ^ .ΐ? 68 \ flb / Κη: ;; "

Bobert Bosch GmI) H, Stuttgart '"* ^f ·

In this through hell 54 ¹ ^ the catch 35 arresting part idle position, the clutch''11 is re-engaged via an auxiliary contact (not shown), for example on the locking lever 36 ', and the engine-side gear half is brought to the engine speed via the drive shaft "45. "The motor speed continues to decrease until the synchronism of the gearbox 12 is achieved. At the same time, the potential of the nodes 66 and 69 becomes more positive again; At the moment of the synchronism, the node 66 still has a negative potential, ie nothing changes in the switching state of the trigger amplifier 77 The "node 69 on the other hand gets back there" potential zero, transistor 78 ¹ becomes non-conductive, transistor 79 'switches to the conductive state and transistor 82 becomes non-conductive. Thus, no more current flows through the control lines 59 and 62, the electromagnet 38 acts as a release device and the tension spring 57 pulls the locking lever X 36 into a position in which it releases the roller 34. D The shift lever I5 is now immediately activated by the energy stored in the double spring 23, jL »^ deja. ^^., gear, switched / fe, ._ · ;. (Fig. 7) · This means that the third process is complete. Slide _; 4; ie.;. Dpppelfeder 23; only accelerate the mass of the shift lever 15 and the transmission parts. got to, -

■ ■ '■'"■" ■■■■■ ^: - "" - "·· ■■■■ '■■■' ^: "'"''"■'"-" ^ "''."'" ^;" ■ "

while the engine 19, its own. Brehmas.se and - the 'entire' shift linkage -, 16 - 18 would have to accelerate is. dies.e arrangement Very, precautionary,,, -; ·

When downshifting, e.g. from,, second ^. ^ Jdan ^ ers.t ^ t

first the changeover switch 90 is actuated. · couples and the motor I9 counterclockwise (related to Pig. 2,] h-uv -;., is driven ». '

ι · - ν ? - Γ » r.

ORIGINAL INSPECTS) ""! * *

(B 79 5Ό1 XIl / 47h'V \ ^: *. · ../ :, ".,; Z ^,

Hpl> e £ t Bosch GmbH, Stuttgart

At the same time, the potentials of the nodes "66 and" 69 are now spr ^ g- ·

It is positive, because in the second flip-flop amplifier 80 "it doesn’t change anyhow" because its input value was already zero. The first KippvVrs ^ arker'77, on the other hand, whose input base was previously at negative potential, is now reversed. Its input transistor 78 becomes non-conductive and the transistor switches to the conductive position. The control lines 59 and 61 "receive " current, the servomotor 42 opens the throttle 44 and the motor is accelerated. The double spring 23 is wound up by the running motor 19, as previously described, and the clutch 11 is re-engaged. This accelerates the motor-side half of the transmission When synchronism is achieved, the second node i66 again has a 'negative potential, ie the transistor 78' becomes lower

Transistor 79 toggles in a non-conductive state and the cöitt ^ gket 38 is de-energized and releases the Sperrhei 36, so that the internal. d ^ ^; 'Dö "gp'elfeder 23 stored energy can engage first gear *

The process of reversing into the other forward gears takes place in the same way. To move from second to third gear, the motor 19 must turn clockwise sian are rubbed, also when switching "from the third to the second Corridor. From third to fourth gear "the M9 engine is counterclockwise" "" driven, and clockwise from fourth to third gear. Γ;

-15-

ORlSlNAL

- 15 - ι ^ ouo.ijt *

(S 79 501 XIl / 47h) 24 · 5 · 196β Rb / Κη

Robert Bosch GabH _f Stuttgart

Of course, the electromagnet 38 can also use an intermediate relay be actuated, the coil of which takes the place of the resistor 99. as well the resistors 96 and 102 can be replaced by intermediate relays whose Contacts actuate servomotors 42 and 45 «In the case of pneumatic or hydraulic actuation, the resistors mentioned can also be replaced by the Kick the coil of the corresponding servo valves »

The tacho generators can be conventional direct current generators with collectors •• in · However, alternating current generators with a high number of pole pairs can also be used and their output voltage can be rectified. To generate the speed-dependent control voltages U ₁ and U- , magnetic or optical pulse generators can also be used, each of which is followed by a monostable multivibrator of constant pulse duration, which feeds an integration stage, with the output voltage being fed to the integration stage of the bridge circuit that a sufficiently large number of pulses is generated per shaft revolution so that the time constant of the integration stage does not have to be selected too high. In principle, it is also possible to use the ignition system of the internal combustion engine as a pulse generator for generating ₍ • a control voltage proportional to the drive shaft speed, if in this case the pulse sequence frequency is high enough

The inevitable temperature variation of the switching points of the two flip-flop amplifiers 77 * 80 can be eliminated by a simple circuit addition, which is shown in Fig. 9, the otherwise unchanged circuit according to Fig. 8 is shown only in part * With this circuit

909810/0400

OWÖINAL INSPECTED, - 16 -

(B 79 50i'xil / 47h) 24-5 * 1968 Rb / Κη,

Robert Bosch GmbH * Stuttgart

In addition, there is a series circuit of a resistor in parallel with the battery 73 104 and a diode 105, the anode of which is connected to the positive pole of the battery 75 ver is bound. With the cathode of the diode 105 is the first node 65 and the Base point of the voltage divider 86 to 89 connected.

The resistor I04 is chosen so that the diode is in the conductive part of its Characteristic works, namely to the right of the bend in its characteristic, i.e. in that Part of the characteristic with great steepness,

This lies between the first node 65 and the positive line 72 Arrangement of a diode voltage XL, the size of which depends on the ambient temperature The emitters of the input transistors 78 and 78 'thus have a potential

which is more positive than the first node 65 by the amount XL ·. Through this the temperature-dependent changes in the input threshold voltages TJ

largely compensated, since the forward voltage of the diode has approximately the same temperature coefficient as the emitter diodes of the transistors. The circuit described has the gate part, since both input transistors 78 and 78 ^{f are} compensated with a diode

Instead of the trigger amplifier, simple DC voltage amplifiers can also be used be, z * B. an amplifier with a pnp transistor in the input stage and a second amplifier with an npn transistor in the input stage, the in each case to positive or negative potential changes in the output voltage address a single bridge. Sensitive relays, e.g. polarized Relays, can be used as voltage-dependent switches. The described Circuitry has the advantage of using a small battery voltage and to use the transistors only a little, since they work hard in switching operation.

■ * · »· ■ 9

Claims (5)

(B 79 501 XIl / 47h) Robert Bosch GmToH, Stuttgart "n.r i.imit been fldert J E, 829ο 24,5,1968 Rb / Κη Today claims 1.) Switching device for a gearbox, especially for an un- synchronized motor vehicle change gearbox, with a servo motor for Operating a switching element of the gearbox, wherein during the SehaltVorgangs kept the switching element in its idle position for so long is until the gear to be engaged is synchronized, characterized in that between the servo motor (19) wad the switching element (I5) an energy store, in particular a spring (23) is arranged »that a Lock (34, 35, 36) for holding the switching element (15) in the idle position of the transmission is provided and that an electronic control device is provided which, when synchronism is reached, the. Lock releases, - 2.. Switching device according to claim 1, characterized in that in itself in a known manner with the transmission input (45) a first voltage generator (48) with the transmission output. (46) a second voltage generator (50). is connected, both of which generate a voltage dependent on their drive speed, their outputs being connected to a device (53) for voltage comparison ', and that this device with the ■ *> ■ -. Lock in active connection stent. ■; ■ · 3. Switching device nach.Anspruch 2, characterized in that for the output of at least one voltage generator (50) a voltage divider ;; (86 to . 69) is connected in parallel, whose resistances correspond to the desired Gear reductions / UÄterteilf are ·:. .. -. 90 9 8.1 OV (B 79 ^ 01 XIl / 47h): · 24.5.1 968 Rbyfcn ■ Robert Bosch GmbH5 Stuttgart. . "-.-: ■;;.. -Γ 4. Switching device according to Claim 2 or 5, characterized in that j.daß = the voltage generator (48 »50) parts of a particular four-branch Bridge connections are each in one of two over, one first Node (65) lying in a row bridge branches, .that in the third and fourth, via a second node (66) in series, lying Bridge branches resistors (6?, 68) are, and that at least a voltage-dependent switch (77) is provided> whose input is connected to the first and the second node 5 · .vSchalteinriehtung according to claim 4 »characterized in that at least one of the bridge branches contains switching elements (86 to 90), the one . Allow the bridge to be adjusted to a desired speed ratio. 6. Switching device according to claim 4 or 5, characterized in that at least one voltage-dependent sehalter a tilting amplifier (77> 80) 1, switching device according to claim 6, characterized in that two further bridge branches containing resistors (70, 7Ό and connected in series via a third node (69)) are connected in parallel to the third and fourth bridge branches, so that the input of a first trigger amplifier (77) is connected to the like .exi the first (65) and the second node (66) is connected, that the input of a second trigger amplifier (80) is connected to the first (65) and the third node (69) and that the second trigger amplifier has a phase inverter (81) downstream is « 9Q ⁰¹ A <1 U50694 (B 79 501 XIl / 47h) 24. 5. I968 fib / Κη Robert Bosch GmbH, Stuttgart * 8. Switching device according to claim 6 or 7 »characterized in that the flip-flop amplifier (77 »βθ) as from an independent voltage source (73) fed transistor amplifiers are designed that parallel to DC voltage source a series circuit of a resistor (104) and a semiconductor diode (105) and that on the semiconductor diode falling voltage as a correction signal to the transistor multivibrators (77, 80) is supplied. 9 · Switching device according to claims 1 and 7 »characterized in that that to the output of the first flip-flop amplifier (77) and to the output the phase inversion stage (81) an OR gate (83) is connected, whose Output controls the release device (37 * 38) for the lock (34 »351 36). 909810 / OiOO