Electronic arrangement for idling stabilization

An electronic arrangement for idling stabilization between a signal transmitter for ignition spark formation and an ignition device for internal combustion engines, by means of which, at a dropping engine rotational speed, the ignition timepoint is advanced below a first engine rotational speed, in which there presently is retarded a pulse obtained from the signal transmitter and, with regard to the contemplated unretarded pulse sequence, is transmitted as an advanced signal to the ignition device whereby the unretarded pulses are emitted externally of the stabilization range intermediate the first and a second lower engine rotational speed. The delay device essentially consists of a sawtooth generator which is triggered by a side of a pulse emitted from the signal transmitter, which is connected at the output thereof with a storage, as well as with an amplifier having a threshold switch, whose outputs are conducted to a comparator which is so correlated that, upon the exceeding of a value stored in the storage, a signal is emitted at the amplifier output which, after further processing, is conducted to the ignition device. Thereby, the operational behavior of simple constructional components and circuit groups is employed so as to achieve, at a falling engine rotational speed within the stabilization range, initially a constant delay period and thereafter an increasing delay period at a constant advance ignition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an electronic arrangement for idling 
stabilization between a signal transmitter for ignition spark formation, 
for instance a Hall generator, and an ignition device for internal 
combustion engines. Pursuant to the present invention, at a dropping 
engine rotational speed, the ignition timepoint is advanced below a first 
engine rotational speed, in which there presently is retarded a pluse 
obtained from the signal transmitter and, with regard to the contemplated 
unretarded pulse sequence, is transmitted as an advanced timing signal to 
the ignition device whereby the unretarded pulses are emitted externally 
of the stabilization range intermediate the first and a second lower 
engine rotational speed. 
2. Discussion of the Prior Art 
An arrangement for idling stabilization which is presently being marketed 
operates with a constant delay period over the entire stabilization range 
and, consequently at reducing engine rotational speed with an increasing 
advance ignition. Technologically, from the standpoint of the engine, such 
an operational characteristic is not satisfying. Operational 
characteristics are desirable in which the range having a constant delayed 
period, in essence with an increasing advance ignition, has an adjoining 
range with an increasing delay period and a constant advance ignition. 
Such an operational behavior of the stabilization device takes into 
consideration that, due to the engine characteristics curve, the initially 
increasing advance ignition produces a growing torque, and that during a 
further dropping rotational engine speed, a relatively retarded or held 
back advance ignition allows for an increase in the torque. 
Through an idling stabilization arrangement it is possible to achieve a 
smooth running for a cold engine, as well as also for a warmed up engine, 
at the lowest fuel consumption. The desired operational cycle 
theoretically requires a high demand on components and circuit technology 
which renders the commercial success questionable. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to effectuate the 
described sought after operational cycle through the intermediary of an 
electronic arrangement for idling stabilization which operates with 
relatively few constructional components and low demand on circuitry 
technology. 
The foregoing object is achieved pursuant to the invention, in that the 
delay device essentially consists of a sawtooth generator which is 
triggered by an edge of a pulse emitted from the signal transmitter, which 
is connected at the output thereof with a storage, element such as a 
capacitor as well as with an amplifier having an element non-linear with 
respect to the voltage, for example a threshold switch in the feedback 
branch of the amplifier whose outputs are conducted to a comparator which 
is so correlated that, upon the exceeding of a value stored in the storage 
capacitor, a signal is emitted at the amplifier output which, after 
further processing, is conducted to the ignition device. Thereby, the 
operational behavior of simple constructional components and circuit 
groups is employed in an advantageous manner so as to achieve, at a 
falling engine rotational speed within the stabilization range, initially 
a constant delay period and thereafter an increasing delay period at a 
constant advance ignition. Since the sawtooth voltage requires a constant 
time period up to acceleration to the threshold value, there is initially 
achieved a constant delay. Above the threshold value the amplification, 
among other functional prerequisites, serves for an increasing delay and a 
constant advance ignition. Each amplification factor hereby corresponds 
to, as in the diagram, an advance in ignition above a predetermined 
plateau level of constant advance ignition above the engine rotational 
speed. 
A particularly simple and advantageous processing of the signal emitted at 
the amplifier output evidences the feature that: 
the comparator includes a differentiating element at the output thereof, 
that the output of the comparator is connected with a monostable flip flop, 
which includes a controlled switch whose control input is connected with 
the comparator, and which at the input side thereof is connected with the 
storage and at the output side with the input of the actual monostable 
flip flop, which contains a storage capacitor connected in parallel to its 
control input, which is bridged over by a discharge branch, 
and wherein the outputs of the monostable flip flop, which represent the 
outputs of the delay device, are connected with the input of a priority 
circuit, at whose further inputs there is produced a connection to the 
input of the electronic arrangement for idling stabilization. The priority 
circuit is so designed such that a signal at its input terminals from the 
monostable flip flop is conducted along to its output, and without such a 
signal the input which is connected to the input of the electronic idling 
stabilization will be connected with its output. 
This result in a monostable pulse in the monostable flip flop which is 
influenced in its duration by the maximum value of the sawtooth in the 
storage capacitor behind the sawtooth generator. It is essential that the 
keying ratio remains constant from pulse to non-pulse. Thereby it becomes 
possible that from two edges of the pulse which is introduced from the 
signal transmittor, in essence, from the negative going and from the 
positive going edge to a lead off a triggering signal. The theorectically 
required demand on constructional elements and circuit technology is 
hereby further reduced, in actual practice, by about one-half. 
In order to assure that a maximum stored valve is attained in a particular 
simple manner, it is advantageous when there are located between the input 
of the arrangement for electronic idling stabilization and the storage, 
capacitor in essence, the sawtooth generator, pick ups of a 
differentiating element for two short sequentially following pulses, 
wherein this differentiating element forms on its input side the input of 
the delay device. This arrangement assures that there can be recorded in 
the storage capacitor, shortly before the sawtooth generator begins to 
operate, whereby the voltage which is recorded from the sawtooth generator 
is a linear representation of the time interval between two trigger edges 
of the signal from the signal transmitter. 
A particularly simple priority circuit comprises two differentiating 
elements of operative resistors, which are interconnected, whereby the 
arrangement, together with two inverters attached to the connecting 
location in series form a bistable flip flop, in that from one operative 
resistor there is formed one connection between the inverters and from the 
other operative resistor a connection at the output of the second 
inverter. Such a priority circuit can, in general, be advantageously 
utilized.

DETAILED DESCRIPTION 
The exemplary embodiments are now explained in detail hereinbelow; 
The electronic arrangement for idling stabilization pursuant to FIG. 1 
consists of a Schmitt-trigger with an inverter, the element 1, as well as 
a delay device 2 and a priority circuit 3 (FIG. 12 can also be referred to 
for a more detailed schematic diagram of the electronic arrangement for 
idling stabilization). The Schmitt-trigger with inverter, element 1, 
includes the input terminal 201 and the output terminal 202. The delay 
device 2 has the input terminal 203 and the output terminal 204. The 
priority circuit 3 includes the input terminals 205 and 206, as well as 
the output terminal 207. The network is completed by the operating voltage 
UB, in actual practice a positive operating voltage and through a ground 
potential. When the delay device emits a signal at its output 204, the 
priority circuit conducts a signal to its output 207. When the delay 
device 2 does not emit a signal at its output 204, then the priority 
circuit transmits the signal from the output 202 to its output 207. Within 
the stabilization range, the delay device 2 emits a signal at its output 
204. The Schmitt-trigger with inverter 1 merely serves, in a known manner, 
to clearly shape the signal present at input 201 from the signal 
transmitter. 
The delay device 2 in the exemplary embodiment pursuant to FIG. 2, consists 
essentially of the following constructional elements: 
a differentiating element 4, 
a sawtooth generator 5, 
a storage circuit 6 which can include a storage element such as a capacitor 
an amplifier with threshold switch, element 7, 
a comparator with a differentiating element, 
element 8, 
and also a monostable flip flop 9. 
The differentiating element 4 includes the input 203 and two outputs, 208 
as well as 209. The connection to ground is identified by reference 
numeral 210. The sawtooth generator 5 has the input 211 and the output 
212, as well as the connection 213 for the operating voltage and the 
connection 214 to ground. The storage circuit 6 for storing of the maximum 
value of the sawtooth includes the inputs 215 and 216, as well as the 
output 217. The connection for operating voltage is designated with 
reference numeral 218. The amplifier with threshold switch 7 includes the 
input 220, the output 221, as well as the connection 222 for operating 
voltage and the connection 223 to ground, respectively, earth. The 
comparator with differentiating element 8, includes the inputs 225 and 
224, the output 226, as well as the connection 227 to ground. The 
monostable flip flop 9 includes the inputs 228 and 229, as well as the 
output 204. At connection 230 there is present the operating voltage and 
at the connection 231 this leads to ground. 
The operational characteristics line in the schematic pursuant to FIG. 3 
evidences within the stabilization region the linearly rising side from A 
to B at a constant delay time and increasing advance ignition, and a level 
plateau region B C with an increasing delay time and a constant advance 
ignition. 
Set forth hereinbelow are exemplary embodiments of the construction of the 
individual circuit elements on the basis of FIGS. 4 through 11: 
The supply voltage plus UB for a Schmitt-trigger with an afterconnected 
inverter, 1, pursuant to FIG. 4, is present at a resistor 100 for 
correlation with the output of a resonance transmitter employed, for 
example, as a signal transmitter for the ignition spark formation with an 
open collector output. At the side of the resistor 100 remote from the 
battery voltage there is located the input terminal 201, which is 
connected with the actual part of the Schmitt-trigger. It consists of a 
resistor 101 and a parallel circuit located in series of resistor 102 and 
two inverters 103 and 104 here positioned behind each other in the 
parallel branch. The parallel circuit has a further inverter 105 connected 
to the output thereof which facilitates that one can operate in the 
electronic idling stabilization with differentiating elements. The output 
of the Schmitt-trigger is designated with reference numeral 202. 
The priority circuit 3 with the input terminals 205 and 206 and the output 
terminal 207 is constructed, pursuant to the embodiment of FIG. 5, through 
a first differentiating element which, in turn, is formed through an ohmic 
resistor, a condenser 106, and operative resistors located in parallel at 
its output, the resistors 107 and 108, and a second differentiating 
element which is formed by an ohmic resistor, a condenser 109, and then 
again by operative resistors located at its output, the resistors 107 and 
108. The resistors 107 and 108 form, together with two inverters 110 and 
111, a bistable flip flop 300 whose input is the terminal point 150 and 
whose output is the terminal point 151. The resistor 107 lies in parallel 
to the inverters 110 and 111 which are arranged in series. The resistor 
108 is arranged in parallel to the inverter 110. At equally large 
resistors 107 and 108 the input 109 is located at mid-potential relative 
to the supply voltage which, in a usual manner, is to be assumed present 
at the inverters 110, 111. The bistable flip flop 300 has a resistor 112 
and a transistor 113 in a so-called open-collector circuit connected to 
the output thereof in order to allow for correlation to a transistor 
ignition. These elements, resistor 112 and transistor 113 are not 
significant to the manner of operation of the electronic idling 
stabilization. The output terminal 207 can hereby also be assumed to be 
ahead of the then lacking resistor 112. 
The elements of the delay device 2 pursuant to FIG. 1, with the input 
terminal 203 and the output terminal 204 are as effectuated in the 
exemplary embodiment as follows: 
The differentiating element 4, pursuant to FIG. 6, with the input terminal 
203 includes two output terminals, 208 for a first needle pulse, and 209 
for a shortly thereafter following second needle pulse. The 
differentiating element 4 consists essentially basically of a condenser 
114 and two in series connected resistors 115 and 116 which are connected 
to ground at the terminal 210. The connector terminal 208 lies between the 
resistors 115 and 116. A second differentiating element with the condenser 
117 and the resistor 118 which is connected to ground is coupled to the 
first differentiating element through an inverter 119. When at the first 
differentiating element behind the condenser 114 the formed needle pulse 
drops off, then the output of the inverter moves into the high condition, 
which is reshaped through the second differentiating element into a needle 
pulse. Thereafter there is also present at the output terminal 208 a first 
needle pulse, and shortly thereafter, when the first needle pulse has 
dropped off, a second needle pulse at the output terminal 209. 
The sawtooth generator 5, i.e. the delay device 2, with the input terminal 
211, the output terminal 212, and the terminal 213 for the connection to 
the voltage supply, for example plus UB, and the terminal 214 for ground 
potential is effectuated in the embodiment pursuant to FIG. 7 as follows: 
The input terminal 211 is connected with the control input of an electronic 
switch 120, in the exemplary embodiment a CMOS component, a so-called 
bilateral switch. The electronic switch 120 is located in the input 
circuit of an operational amplifier 121 and namely, at the non-inverting 
input. The inverting input is connected to ground through the resistor 122 
by means of the terminal 214. The illustrated wiring of the operational 
amplifier 121 with the resistors 123, 124, 125, 126 and 122, as well as 
with the condenser 127 permits the operational amplifier to operate as a 
sawtooth generator. When a needle pulse appears at the input terminal 211, 
then the electronic switch 120 becomes conductive and the condenser 127 
discharged, whereby the operational amplifier 127 is set to the minimum 
voltage, in effect to zero. Triggered thereby is the formation of a 
sawtooth. This procedure repeats itself upon the incidence of the 
subsequent needle pulse. 
The storage 6 of the delay device 2, with the input terminals 215 and 216 
and the output terminal 217, as well as the terminal 218 for connection of 
the supply voltage, is formed in the exemplary embodiment pursuant to FIG. 
8 through an electronic switch 128, for example, a CMOS switch, and a 
condenser 129. Proceeding from the input terminal 216, the electronic 
switch 128 with the condenser 129 lies in series with the terminal 218 for 
the supply voltage. The input terminal 215 leads to the control input of 
the electronic switch 128. Effected between the switch 128 and the 
condenser 129 is the pickup to the output terminal 217. The input terminal 
215 receives the take-over command and the input terminal 216 operates as 
storage input as long as the take-over command is present at the input 
terminal. When a positive needle pulse is present at the input terminal 
215, then the electronic switch 128 is controlled to be conductive and a 
voltage which is present at the input terminal 216 charges the condenser 
129 over so that the information which is present at the input terminal 
216 is read into the storage in the form of a voltage level. 
The amplifier with the threshold switch, element 7 of the delay device 2, 
has pursuant to FIG. 9 the input terminal 220 and the output terminal 221, 
as well as the terminal 222 for connection to supply voltage, and the 
terminal 223 to ground. The input terminal 220 is connected with the 
non-inverting input of an operational amplifier 130. The output of the 
operational amplifier 130 is coupled back to the inverting input through 
an electronically controlled switch 131, in the exemplary embodiment as 
CMOS switch, and a resistor 132. Through the resistors 133, 132 and the 
resistor 134, between the supply voltage and ground, there is formed 
between resistors 132 and 134 the pickup for a voltage divider. The latter 
is connected to the inverting input of the operational amplifier 130. 
Thereby there is set at the operational amplifier 130 a threshold value of 
##EQU1## 
When the voltage present at the input terminal 220 reaches the 
predetermined threshold value, then the operational amplifier 130 is 
actuated, so that the switch 131 is controlled to be conductive. The 
operational amplifier 130 now operating as a non-inverting proportional 
amplifier has the amplification factor V130 
##EQU2## 
In the exemplary embodiment there is also provided a resistor 135 
intermediate the output of the operational amplifier 130 and the output 
terminal 221. 
The comparator 800 with the differentiating element 801, component group 8 
of the delay unit 2, pursuant to FIG. 10 includes the input terminals 224 
and 225, as well as the output terminal 226 and a terminal 227 for 
connection to ground. An operational amplifier 136 is operated as a 
comparator; connected to the output thereof is a differentiating element. 
The differentiating element consists of a condenser 137 and a resistor 
138. The input terminal 225 is connected with the non-inverting input and 
the input terminal 225 with the inverting input of the operational 
amplifier 136. Formed intermediate the condenser 137 and the resistor 138 
is a connection to the output terminal 226. When the voltage present at 
the input terminal 224 exceeds the voltage present at the input terminal 
225, then the comparator is switched through so that a high-signal is 
present at its output. The positive side, during transition to the 
high-signal, at the output of the of the operational amplifier 136 is 
reshaped by the differentiating element into a needle pulse which stands 
available at the output terminal 226. 
The monostable flip flop 9 pursuant to FIG. 11, the delay device 2 with the 
input terminals 228 and 229 and the output terminal 204 as well as the 
terminals 230 for connection to supply voltage, and terminal 231 for 
connection to ground is equipped so as to emit an output signal of 
adjustable duration. Connected to the non-inverting input of an 
operational amplifier 139 through an electronically controlled switch 140, 
in this embodiment a CMOS switch, is the input terminal 228. The signal 
which is here present from the storage acts as a time setter. Connected at 
the control input of the switch 140 is the connector terminal 229 which 
acts as a trigger unit. Hereby there is also determined at which point in 
time a signal stands available out the output. The inverting input of the 
operational amplifier 139 is subjected to a threshold value through the 
resistors 141 and 142 which operate as voltage dividers. The non-inverting 
input of the operational amplifier 139 lies connected to ground through 
the condenser 144 and a herewith parallel arranged resistor 143. 
When the input terminal 229 of the switch 140 acting as a trigger input is 
conductively controlled, then a voltage level present at the input terminl 
228 as a time determinate can charge the condenser 144. Upon the charging 
of the condenser 144, the output of the operational amplifier 139 is 
converted into its high-condition. With an attenuating triggering signal 
at the input 259, the switch 140 will open and the condenser 144 can 
discharge across the resistor 143. When one falls below the set threshold 
value at the inverting input of the operational amplifier then the output 
of the operational amplifier 139 drops back into its low-condition. 
The duration of the high-signal is proportional to the voltage introduced 
into the condenser 144. This introduced voltage is, in turn, proportional 
to the periodic interval of the signal transmitter for the condition spark 
formation connected at the input side of the idling stabilization. Thus, 
the duration tH of the high-signal is proportional to the duration of 
period TS of the signal transmitter. Thereby, also the duration tL of the 
low-signal is proportional to the period duration TS. As a result also the 
keying ratio T is constant from the duration of the high-signal to the 
duration of the low-signal. 
Then tH=k1.times.TS; tL=k2.times.TS and thus 
##EQU3## 
Hereinbelow is described the mode of operation of the device for the 
electronic idling stabilization: 
When there is present at the input of the electronic arrangement for idling 
stabilization, a signal from the signal transmitter for the ignition spark 
formation, for instance pursuant to FIG. 13, the signal from the input 
stage, in the exemplary embodiment pursuant to FIGS. 1 and 4 a 
Schmitt-trigger with inverter, component group 1, is cleared of disturbing 
influences so that there is obtained a signal pursuant to FIG. 14. In this 
and in the following schematic representations there is always illustrated 
the time on the abscissa and the signal as voltage on the ordinate. In 
FIG. 13 there is thus plotted the voltage of the signal from the signal 
transmitter, the input voltage U201 with the cycle 20. It is present at 
the input terminal 201 of the arrangement for idling stabilization. At the 
output 202 of the input stage, in essence at the output of the 
Schmitt-trigger with inverter 1, the voltage 202 stands available with the 
cycle 21 pursuant to FIG. 14. When the operative mode of the delay device 
2 pursuant to FIG. 1 is initially combined there is then delayed a voltage 
U 202, pursuant to FIG. 15, so that the first differentiating element of 
the priority circuit 3, pursuant to FIGS. 1 and 5, with the input 205, 
renders available at its output the voltage UD1 pursuant to FIG. 16 with 
the cycle 22. With respect to the undelayed contemplated signal pursuant 
to FIG. 15, in effect, at the output of the second differentiating element 
of the priority circuit 3 pursuant to FIG. 17, there is produced a 
timewise delay tv and an advance ignition at the time tf. The voltage UD2 
pursuant to FIG. 17 at the output of the second differentiating element of 
the priority circuit 3, whose input is designated with 206, has the cycle 
23. At the input 150 of the flip flop of the priority circuit 3 pursuant 
to FIG. 5 there is then present the voltage U pursuant to FIG. 18. The 
bistable flip flop of the priority circuit is set into the high-condition 
through the first positive differentiating peak 24 and, by means of the 
first negative peak, is displaced back into the low-condition. The second 
positive signal peak 26 and the second negative signal peak 27 will then 
currently remain ineffective. Accordingly, there is maintained the period 
TS of the signal transmitter, pursuant to FIG. 15, as may be ascertained 
from FIG. 19. Plotted herein on the ordinate is the voltage UL as it is 
emitted at the output of the electronic arrangement for idling 
stabilization at an operative point within the stabilization range. 
Externally of the stabilization range there is currently present at the 
input of the flip flop of the priority circuitry only the positive signal 
26 and the negative signal 27 so that there is obtained at the output of 
the flip flop a signal cycle corresponding to 21 pursuant to FIG. 15, in 
effect, undelayed. Externally of the stabilization range there is thus 
further transmitted unchanged the signal from the signal transmitter in 
its information content. 
Within the stabilization range there is achieved an advance ignition at the 
time tf=TS-tv. With respect to the undelayed contemplated signal there are 
then available advanced signals at the output of the arrangement for 
idling stabilization. Through the negative side, signals from the signal 
transmitter, respectively through the positive side of the inverted 
signal, as generated through the input stage, namely through a 
Schmitt-trigger with inverter, there is effected the initiation of the 
ignition spark. 
The manner of operation of the delay device 2 pursuant to FIG. 1, which is 
shown in greater detail in FIG. 2, is now elucidated pursuant to the 
description in FIGS. 20 through 38. 
The voltage from the output 202 of the input stage is present at the input 
203 of the delay device as U203. Its cycle 21 is again illustrated in FIG. 
20. The differentiating element 4 produces in this exemplary embodiment 
first needle pulses 28 pursuant to FIG. 21, which are emitted at output 
208, and at a short time interval thereafter, second needle pulses 29 
pursuant to FIG. 22, which are emitted at the output 209. By means of the 
needle pulses pursuant to FIG. 22, from the positive side of signal U203 
at the output of the input stage, in the exemplary embodiment the 
Schmitt-trigger with inverter, there is triggered the sawtooth generator 5 
which generates the voltage U with the cycle pursuant to FIG. 24. The 
duration of the sawtooth voltage is a linear representation of the time 
cycle during the period of the signal from the signal transmitter, in 
effect, the signal U at the output 202. The period TS can thus also be 
understood as being the period TS of the sawtooth signal. 
In FIG. 25 there is again represented the cycle 30 of the sawtooth voltage. 
This voltage is present at the input 220 of the amplifier with the 
threshold switch, element 7. The threshold value is designated with 
reference numeral 31. At the output 221 there is then available a voltage 
cycle 32 pursuant to FIG. 26. 
The sawtooth voltage at output 212 of the sawtooth generator 5 is also 
conveyed to the storage 6, in which there is stored the current maximum 
value of the sawtooth voltage. Through the needle pulse U208 pursuant to 
FIG. 21 there is assumed the instantaneous values of the sawtooth in the 
storage 6. However, since this needle pulse occurs immediately ahead of 
the zero setting of the sawtooth, this instantaneous value corresponds to 
the maximum value of the sawtooth. This maximum value is directly 
proportional to the duration of the period of the signal from the signal 
transmitter for the ignition spark formation and thus is inversely 
proportional to engine rotational speed. The maximum value is stored and 
stands available up to the zero setting with the next sawtooth at output 
217. 
The threshold value which is set at the threshold of the amplifier with the 
threshold switch, component group 7, corresponds to a predetermined delay 
time tv. When the sawtooth voltage 30, due to a shorter period cycle ts 
does not reach the threshold value 31, then no signal will be present at 
output 221. 
The comparator 800 with the differentiating element 801, component group 8, 
however, delivers a signal at output 226 only when the voltage at the 
input 224 reaches or exceeds the stored maximum sawtooth voltage which is 
present at input 225. In the just described instance, the stabilization 
arrangement operates externally of the stabilization range. 
When the period duration TS of the signal from the signal transmitter for 
ignition spark formation serving as the input signal corresponding to the 
period duration of the sawtooth impulse, is so large that the sawtooth 
voltage reaches the set threshold value, then the comparator 8 receives an 
input signal at its input 224. The beginning of the stabilization range is 
illustrated in FIGS. 27 through 30. 
For the input voltage 21 pursuant to FIG. 27 which is present at input 203, 
the sawtooth voltage 30 pursuant to FIG. 28 can just reach the preset 
threshold value 31. Due to the amplification through the amplifier with 
the threshold switch of the component group 7, the voltage 31 at output 
221 exceeds the maximum voltage 33 of the sawtooth voltage 30 which is 
stored in the storage 6. This is illustrated in FIG. 29. In the component 
group 8, the comparator 800 thus emits a high-signal, to which the 
differentiating element 801 forms a needle pulse which is present at the 
input 229 of the monostable flip flop, component group 9. This forms an 
output signal with constant keying ratio and the monostable time tm, as is 
illustrated in FIG. 30. 
Since the threshold value 31 is always reached after the same time, 
independently as to which period cycle is evidenced by the sawtooth, there 
is obtained a constant delay and at an increasing period cycle of the 
sawtooth voltage, in effect at a reducing rotational speed, a linearly 
increasing advance ignition, as can be seen, for example, from a 
comparison of FIGS. 15 and 16. 
When the period cycle of the input signal ts and, correspondingly, the 
period cycle of the sawtooth is so large that the voltage which has been 
amplified by the amplifier in component group 7 is just as large as the 
maximum sawtooth voltage, then in FIG. 3 there has been reached the upper 
point B of constant delay time and linearly increasing advance ignition. 
This is illustrated in FIGS. 31 through 34. The period cycle ts in FIG. 31 
is to be assumed as larger than that in FIG. 27; only for reasons of 
illustration has it been shown as equal. Upon the actuation of the 
amplifier in component group 7 can the comparator in component group 8 
determine that the maximum sawtooth voltage has been reached and the 
priority circuit is subjected to a delayed signal so that the signal cycle 
is reached pursuant to FIG. 34. With respect to the undelayed signal 21, 
at a delay period of tv this corresponds to an advance ignition tf. 
At a still greater durational period TS of the input signal, the maximum 
sawtooth voltage increases further and, upon reaching of the threshold 
value, the amplifier voltage lies below the maximum sawtooth voltage. The 
operating point now lies in the plateau region pursuant to FIG. 3, in 
effect between points B and C. The manner of function is illustrated in 
FIGS. 35 through 38. Due to reasons of illustration the period duration TS 
of the input voltage is again retained, although it is actually greater 
than in FIG. 31. The amplified voltage 32 pursuant to FIG. 37 upon 
reaching of the threshold value 31 pursuant to FIG. 36, lies below the 
maximum value 33 of the sawtooth voltage. Therefore some time passes until 
the amplified voltage 32 reaches the maximum sawtooth voltage 33 and the 
comparator of the component group 8 emits a signal with the result that 
the priority circuit 3 obtains a signal at its input 205. 
In FIG. 37 there is finally illustrated a limiting voltage 34. When the 
maximum value 33 of the sawtooth voltage lies above this limiting voltage, 
then the amplifier with the threshold switch, component group 7, can no 
longer emit a signal. When the limiting voltage is reached, then the 
amplifier can no longer reach the maximum sawtooth voltage, which 
corresponds the plateau drop off in the operational characteristics line 
pursuant to FIG. 3 at point C. 
The limiting voltage 34 can generally be understood as a second threshold 
value. It is essential that commencing from the activation of the 
amplifier in the component group 7 up to the actuation of the comparator 
in the component group 8, there is traversed an additional delay time 
period t'-tv. This tv' is by so much larger than tv, pursuant to FIGS. 31 
through 34, the more time there is traversed towards reaching of the 
maximum sawtooth voltage 33 through the amplified voltage 32. As is 
illustrated on the basis of FIG. 38, the operative point now lies in a 
region of increasing delay time. It is, however, essential that due to the 
indicated circuitry there is achieved a constant advance ignition angle 
.alpha., wherein 
##EQU4## 
When the amplifier has the amplification factor k, there is obtained 
between the advance ignition, measured in angular degrees .alpha. and the 
amplification, the relationship 
##EQU5## 
The advance ignition .alpha. in degrees corresponds to a predetermined 
plateau height in FIG. 3. 
When, in the component group 8, the comparator 800 a signal at the input 
224 determines that the maximum value of the saw tooth voltage at input 
225 has been reached or exceeded, then its differentiating element 801 
emits a needle pulse which is present at the input 229 of the monostable 
flip flop 9. The monostable flip flop then delivers a signal of constant 
keying ratio T whose monostable time tm depends upon the maximum value of 
the sawtooth voltage from the storage 6. The differentiating element 801 
of the component group 8 delivers during the transition of the comparator 
800 into its high-condition a needle pulse to the positive side, which 
closes the controllable switch through the input 229 of the monostable 
flip flop 9. The keying ratio can be constantly set in a desired manner, 
as can be illustrated based on the following equations: 
##EQU6## 
in effect, constant.