U.S. patent number 3,593,692 [Application Number 04/826,058] was granted by the patent office on 1971-07-20 for electrical fuel injection arrangement for internal combustion engines.
This patent grant is currently assigned to Robert Bosch G.m.b.H.. Invention is credited to Wolfgang Rehmann, Norbert Rittmannsberger, Hermann Scholl, Josef Wahl, Wolf Wessel.
United States Patent |
3,593,692 |
Scholl , et al. |
July 20, 1971 |
ELECTRICAL FUEL INJECTION ARRANGEMENT FOR INTERNAL COMBUSTION
ENGINES
Abstract
An electrically controlled fuel injection arrangement for
internal combustion engines in which the fuel is injected through
electromagnetically controlled valves. A control monostable
multivibrator is actuated through a pulse emitter coupled directly
to the crankshaft of the engine and emitting pulses synchronously
with the speed of the engine. The pulse emitter actuates the
monostable multivibrator which has a variable unstable state. A
pulse generator coupled to the throttle of the engine emits a
sequence of auxiliary control signals which extend the opening time
interval of the injection valves during opening motion of the
throttle, for purposes of increasing the quantity of injected fuel
during engine acceleration.
Inventors: |
Scholl; Hermann (Stuttgart W,
DT), Rittmannsberger; Norbert (Stuttgart I,
DT), Wessel; Wolf (Stuttgart S, DT),
Rehmann; Wolfgang (Stuttgart-Bad Cannstatt, DT),
Wahl; Josef (Stuttgart-Kaltental, DT) |
Assignee: |
Robert Bosch G.m.b.H.
(Stuttgart, DT)
|
Family
ID: |
5692254 |
Appl.
No.: |
04/826,058 |
Filed: |
May 9, 1969 |
Foreign Application Priority Data
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|
|
|
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May 11, 1968 [DT] |
|
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P 17 51 330.3 |
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Current U.S.
Class: |
123/484; 123/492;
123/490 |
Current CPC
Class: |
F02D
41/32 (20130101) |
Current International
Class: |
F02D
41/32 (20060101); F02d 005/02 () |
Field of
Search: |
;123/32,32E,32EA,119,139.18 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Claims
What we claim as new and desire to be protected by Letters Pat.
is:
1. An electrically controlled fuel injection arrangement for an
internal combustion engine comprising, in combination, at least one
electromagnetically controlled injection valve for injecting fuel
into the engine; energizing means connected to said valve for
energizing electrically said injection valve; control multivibrator
means having stable and unstable states and being connected to said
energizing means; first pulse-emitting means connected to said
control multivibrator means and emitting speed-dependent pulses
proportional to the speed of said engine, varying in frequency upon
speed variations of said engine, said pulses triggering said
multivibrator means to said unstable state for opening said valve,
said multivibrator means returning to said stable state after a
predetermined and variable time interval; and second pulse-emitting
means triggered by means actuated primarily during increased demand
for power output from said engine, and emitting at least one
auxiliary pulse between two successive speed-dependent pulses from
said first pulse-emitting means, said auxiliary pulse being applied
to said injection valve for increasing the quantity of fuel
injected during increased demand for power output from the
engine.
2. The fuel injection arrangement as defined in claim 1, wherein
said means actuated primarily during increased demand for power
output from the engine is the throttle of the engine, said second
pulse-emitting means delivering a train of auxiliary pulses during
opening motion of said throttle.
3. The fuel injection arrangement as defined in claim 2, wherein
said second pulse-emitting means delivers at least five auxiliary
pulses distributed over the total opening of said throttle.
4. The fuel injection arrangement as defined in claim 1, wherein
said means actuated primarily during increased demand for power
output from the engine is the throttle of the engine, and said
second pulse-emitting means includes switch contact means; and
switch element means rotatable by said throttle and cooperating
with said switch contact means so that the latter is actuated only
during opening motion of said throttle.
5. The fuel injection arrangement as defined in claim 4, wherein
said second pulse-emitting means comprises further a disc member
coupled to the shaft of said throttle and having a plurality of
teeth distributed along the rim of said disc; and stationary
contact members cooperating with said disc and being in contact
with said teeth during opening motion of said throttle.
6. The fuel injection arrangement as defined in claim 4, wherein
said second pulse-emitting means comprises further two contact
tracks isolated from each other electrically and having radial
cross-contact portions directed opposite to the contact portions of
the other track; and contact finger means movable with said
throttle and contacting said radial cross portions.
7. The fuel injection arrangement as defined in claim 6 including a
third contact track and a second contact finger for maintaining
continuous contact with said third contact track during opening
motion of said throttle.
8. The fuel injection arrangement as defined in claim 7 including
insulating plate means for carrying said contact finger means and
mounted upon the shaft of said throttle.
9. The fuel injection arrangement as defined in claim 8 including
base plate means for carrying said contact tracks; and braking
means for holding said base plate means and said insulating plate
means.
10. The fuel injection arrangement as defined in claim 9 including
a drag switch mounted on said insulating plate means; and actuating
means mounted on the shaft of said throttle and actuating said drag
switch during opening motion of said throttle.
11. The fuel injection arrangement as defined in claim 10 including
contact springs extending from said contact fingers and located in
the path of said actuating means, each of said contact springs
having contact portions at the end of said spring.
12. The fuel injection arrangement as defined in claim 11 including
auxiliary contact springs secured to said base plate means and
actuated by said actuating means during closing motion of said
throttle.
13. The fuel injection arrangement as defined in claim 12,
including an OR gate means connected to said energizing means and
having one input connected to the output of said control
multivibrator means; and wherein said second pulse-emitting means
includes bistable multivibrator means triggered back and forth
between its two states during opening movement of said
throttle.
14. The fuel injection arrangement as defined in claim 13, wherein
said second pulse-emitting means includes monostable multivibrator
means for determining the duration of said auxiliary pulses, and
differentiating means connected between said bistable multivibrator
means and said monostable multivibrator means.
15. The fuel injection arrangement as defined in claim 14, wherein
said monostable multivibrator means includes an input transistor,
said input transistor being conductive when said monostable
multivibrator means is quiescent, an output transistor coupled to
said input transistor, coupling capacitor means connected between
the collector of said output transistor and the base of said input
transistor, and a diode connected between the base of said input
transistor and said coupling capacitor, said auxiliary pulses being
taken from the collector of said input transistor.
16. The fuel injection arrangement as defined in claim 15,
including regulating voltage-generating means for generating a
voltage varying as a function of the number of said auxiliary
pulses and influencing the duration of the latter, the duration of
said auxiliary pulses decreasing with increasing number of said
auxiliary pulses.
17. The fuel injection arrangement as defined in claim 16, wherein
said monostable multivibrator means includes an input transistor
and an output transistor, a diode connected to the collector of
said output transistor, a first resistor connected in series with
said diode and having a resistance value substantially within the
range of 5 to 50 kohms, a second resistor connected in series with
said first resistor and having a resistance value substantially
within the range of 100 kohms to 300 kohms, storage capacitor means
connected in parallel with said second resistor and having a
capacitance of at least 1 .mu.., and feedback coupling capacitor
means connected between the base of said input transistor and the
junction of said first resistor and said diode.
18. The fuel injection arrangement as defined in claim 17,
including multiplying means connected to said control multivibrator
means and applying a lengthening factor to said pulses from said
control multivibrator means, said lengthening factor being a
function of the number of said auxiliary pulses and being made
variable as a function of a charging current.
19. The fuel injection arrangement as defined in claim 18,
including emitter-follower transistor means for providing said
charging current; a base capacitor connected to the base of said
emitter-follower means; a resistor connected in parallel with said
base capacitor, said base capacitor being charged for every one of
said auxiliary pulses, the discharge time constant of said
capacitor being substantially at least 10 times larger than the
charging time constant.
20. The fuel injection arrangement as defined in claim 19,
including electronic storage means for storing said auxiliary
pulses, and means for adding to said speed dependent pulses those
auxiliary pulses that are overlapped by said speed-dependent
pulses.
21. The fuel injection arrangement as defined in claim 20, wherein
said second pulse-emitting means includes monostable multivibrator
means controlled by said bistable multivibrator means for
generating said auxiliary pulses and having an input transistor and
an output transistor, said auxiliary pulses being delivered by said
output transistor; a base current transistor for supplying current
to the base of the input transistor, said base current transistor
being turned off during emission of a speed-dependent pulse by said
first pulse-emitting means and being turned on upon termination of
said speed-dependent pulse; feedback coupling capacitor means
connected between the collector of said output transistor and the
base of said input transistor; a diode connected between said
feedback coupling capacitor and the base of said input transistor;
and an auxiliary feedback circuit connected between the collector
of said output transistor and the base of said input transistor,
said auxiliary feedback circuit comprising a resistor and diode
connected in series.
Description
BACKGROUND OF THE INVENTION
The present invention resides in an electrically controlled fuel
injection arrangement for internal combustion engines having at
least one electromagnetically actuated injection valve. The
magnetizing coil of the valve is connected in series with a power
transistor which is driven by a control multivibrator. This
multivibrator is transferred to its unstable state through pulses
generator synchronously with the speed of the engine. The injection
valves are opened simultaneously with the occurrence of the
unstable state of the multivibrator. After a predetermined but
variable time interval during which the valves remain open, the
multivibrator returns to its stable operating state. The throttle
flap of the engine, furthermore, actuates an arrangement which
increases the quantity of fuel injected during the opening motion
of the throttle flap.
Electrically controlled arrangement of these species, are known in
the art for the purposes of injecting fuel into the intake manifold
of an internal combustion engine. In such known arrangements, the
throttle flap of the engine is coupled to a pulse generator which
includes an induction coil and a permanent magnet immersed therein.
When stepping upon the gas pedal, the permanent magnet is
introduced into the induction coil and thereby induces a voltage
within the coil. The magnitude of this induced voltage increases
with the opening speed of the throttle flap. In the known
arrangement, the induced voltage is applied to a transistor
amplifier. With the latter, the reference voltage may be varied for
the resetting time and the resulting length of the control pulse of
the control multivibrator which provides the reference voltage. In
this arrangement, the control pulse becomes extended in length or
duration, and this lengthening of the pulse results in increased
quantities of injected fuel for purposes of acceleration
enrichment.
This conventional arrangement which provides enrichment on the
basis of inductance varying with the throttle flap motion, operates
satisfactorily for simple injection arrangements. This conventional
or known arrangement, however, is relatively complex, because the
pulse generator with permanent magnets must be designed with small
airgaps and a very high manufacturing tolerance. These conditions
apply even when a sufficiently large inductive signal is realized
for small or slowly opening movements of the throttle. Pneumatic
systems are known in which the pressure rise within the intake
manifold of the engine becomes differentiated during the opening of
the throttle flap. Such pneumatic arrangements, however, have the
disadvantage that the control signal lags the throttle flap motion
by approximately 40 to 70 milliseconds.
Accordingly, it is an object of the present invention to provide a
fuel enrichment arrangement for accelerating processes, which is
simple in design, and which does not lag the motion of the throttle
flap. It is a further object of the present invention that the
enrichment of the fuel be made dependent upon the opening motion
and the opening speed of the throttle flap.
These objects of the present invention are achieved through a pulse
generator which is coupled to the throttle flap. This pulse
generator delivers a sequence of auxiliary control signals or
pulses for the injection valves, during the opening angular
movement of the throttle flap. The arrangement is such that the
pulse generator provides preferably at least five such auxiliary
pulse signals during the opening motion of the throttle flap. The
pulse generator may be designed with a switching contact and a
switching member cooperating with the contact and rotatable with
the throttle flap. The design is arranged so that the switching
contact actuates the switching element or circuit element only
during the opening motion of the throttle flap.
With such a pulse generator, it is possible, in accordance with the
present invention, to provide additional or auxiliary injection
processes. Such auxiliary injections of fuel result during the
opening motion of the throttle flap, and are in addition to the
injection processes which results synchronously with the crankshaft
rotations of the engine. It is of advantage in such an injection
arrangement to provide at least one power transistor in front of
which is connected an electronic logical OR gate. The power
transistor constitutes the end stage for actuating the
electromagnetically controlled valves. The first of the inputs of
the OR gate is connected to the output of the control multivibrator
which provides pulses synchronously with the rotational speed of
the engine. The second input of the OR gate, at the same time, is
connected to the output of a second monostable multivibrator which
is independent of the control multivibrator, and which is actuated
through the pulse generator coupled to the throttle flap.
SUMMARY OF THE INVENTION
An electrically controlled arrangement for the injection of fuel
into an internal combustion engine during accelerating states of
the engine. The fuel is injected into the intake manifold of the
engine, through electromagnetically controlled injection valves
which are driven or energized by power transistors. These
transistors deliver current to the coils of the injection valve for
the purpose of maintaining these valves in the open state. A
control multivibrator with stable and unstable states is used to
control, in turn, the states of the power transistors. A pulse
emitter is electrically connected to the control multivibrator and
also to the engine so that it emits pulses synchronously with the
speed of the engine. The pulses from the pulse emitter are used to
transfer the control multivibrator from its stable state to an
unstable state in which the electromagnetically control valves are
opened. After a predetermined but variable time interval the
control multivibrator returns to its initial stable state. A pulse
generator is coupled to the throttle of the engine and emits a
sequence of auxiliary control signals, preferably five pulse
signals, for opening the injection valve during the opening motion
of the throttle. These auxiliary control signals function to
increase the quantity of fuel injected into the engine during the
opening motion of the throttle, or the accelerating state of the
engine.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a partial sectional view of the intake manifold of the
engine and shows the design for securing the pulse generator to the
throttle of the engine, in accordance with the present
invention;
FIG. 2 is a partial view of the pulse generator arrangement
connected to the throttle of the engine in FIG. 1;
FIG. 3 is another embodiment of the pulse generator shown in FIG.
2;
FIG. 4 is an isometric view of a further embodiment of the pulse
generator connected to the engine throttle in FIG. 1;
FIG. 5 is a diagrammatic plan view and shows the detail of the
stationary and movable contacts used in the pulse generator of FIG.
4;
FIG. 6 is a partial sectional view through the driving shaft of the
pulse generator of FIG. 4;
FIG. 7 is an electrical schematic diagram of a fuel injection
arrangement for electrically controlling the injection of fuel into
an engine, in accordance with the present invention;
FIG. 8 is a waveform diagram of pulse signals in the circuit of the
embodiment of FIG. 7;
FIG. 9 is an electrical schematic diagram of a second embodiment of
an electronic fuel injection arrangement, in accordance with the
present invention;
FIG. 10 is a waveform diagram of signals associated with the
circuitry of the second embodiment of FIG. 9;
FIG. 11 is an electrical schematic diagram of a further fuel
injection arrangement; and
FIG. 12 is a waveform diagram of the signals associated with the
circuitry of FIG. 11.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawing, and in particular to the first embodiment
shown in FIGS. 1 and 2, a throttle flap or valve member 2 is
rotatably mounted on a shaft 3 within the intake manifold 1 of the
internal combustion engine, in accordance with the present
invention. The shaft 3 of the throttle flap valve member projects,
with its ends, beyond the shaft bearings 4 and 5. A lever 6 is
mounted upon the end of the shaft 3 projecting through the bearing
4 of the intake manifold 1. The lever arrangement 6, furthermore,
is joined to a connecting rod 7 which, in turn, is coupled to the
gas pedal, not shown, of the internal combustion engine. Through
means of a return spring, the lever arrangement 6 may be acted upon
to rotate the shaft 3 so that the throttle flap member 2 is in the
open position, as shown in the diagram of FIG. 1.
A gear 8 is mounted upon the end of the shaft 3, projecting from
the bearing 5. A lever 9 is, furthermore, securely fixed to the
throttle flap shaft 3. The free end of the lever 9 carries a pawl
10 which is acted upon by a spring, not shown. The teeth of the
gear 8 have the profile of ratchet teeth which engage the pawl 10.
The ratchet teeth and engaging pawl are oriented so that the
ratchet 8 may be rotated through motion of the pawl 10 only when
the lever 9 carrying the pawl 10 rotates in the direction of the
arrow shown on the ratchet wheel 8 in FIG. 2.
Leading to the outside of the intake manifold 1, are two
strip-shaped contact-carrying members 12 and 13 made of preferably
red brass or tombac which is a copper-base zinc alloy. Contacts 14
and 15 are provided at the free spring ends of the blades or
members 12 and 13 which are electrically isolated from each other.
Furthermore, at least one of the contact carrying members 12 and
13, is electrically isolated with respect to the intake manifold 1.
The contact-carrying member or blade 13 has a tongue portion 16
projecting from the location at which the respective contact 15 is
secured. This tongue portion or blade 16 operates in conjunction
with the ratchet teeth of the ratchet wheel 8. When the ratchet
wheel 8 is rotated in the direction of the arrow shown in FIG. 2,
through motion of the pawl 10 when opening the throttle flap, the
tongue portion 16 moves toward the carrying blade 12 and thereby
causes the contacts 14 and 15 to produce briefly a closed circuit.
Closure of the contacts 14 and 15 is accomplished whenever the
ratchet wheel 8 is rotated through an angle which corresponds to
the pitch distance of one tooth of the ratchet wheel. In the
embodiment being described, an angle of 90.degree. is rotated or
traversed when the throttle flap 2 becomes fully opened. During
this angular interval of 90.degree., the contacts 14 and 15 will
close, thereby, eight times. The construction of the tongue portion
or blade 16 in relation to the ratchet wheel 8 is such that the
latter is prevented from rotating against the direction of the
arrow shown in the drawing, when the throttle flap is returned to
closed position. Thus, the tongue blade or portion 16 engages the
ratchet teeth such that rotation of the ratchet wheel in the
direction opposite to that shown by the arrow in FIG. 2 is
inhibited. Accordingly, electrical impulses are generated only when
the throttle flap is opened. These pulses derived through the
closure of the contacts 14 and 15 are not generated when the
throttle valve is being closed. The pulses are generated for use in
conjunction with accelerating features.
In a different embodiment shown in FIG. 3, the shaft 22 is
rotatably mounted in bearings of the intake manifold of the
internal combustion engine. The shaft 22 has mounted onto it the
throttle flap, not shown. A gear segment 23 is secured to one end
of the shaft switches 101 projecting to the outside or exterior of
the intake manifold. A contact-carrying member 25 is secured to the
intake manifold 21 and is arranged to lie opposite the gear tooth
segment. When the segment 23 is rotated in the direction of the
arrow shown on the segment, in FIG. 3, the contact-carrying member
25 becomes engaged by the teeth of the segment and is brought into
contact with a second member 26. The gear segment 23 will rotate in
this direction of the illustrated arrow when the throttle flap
mounted on the shaft 22 is being opened. As a result of bringing
together the members 25 and 26 through the action of the gear
segment 23, the contacts 27 and 28 on the members 25 and 26,
respectively, form a circuit closure. Through such circuit closure,
therefore, an enrichment pulse for the electronic control
arrangement associated with the fuel injection structure, may be
realized.
In the embodiment of FIG. 3, in accordance with the present
invention, the contacts 27 and 28 produce a circuit closure
whenever the segment is rotated through an angle which corresponds
to a single tooth pitch. Such circuit closure between the contacts
27 and 28 is established whenever the segment is rotated in the
direction of the arrow, corresponding to opening of the throttle
flap or valve. When, on the other hand, the throttle flap is
rotated for the purpose of closing the throttle, the segment 23 is
rotated in the direction opposite to that shown by the arrow, and
the contact carrying member 25 is carried or moved by the teeth of
the segment, so that the member 25 moves away from the member 26.
Once a tooth of the segment 23 intercepts the member 25 and moves
it away from the member 26, the member springs back to its original
position after release by the intercepting gear tooth when the
latter has moved through a tooth pitch distance. Through proper
design of the teeth of the gear segment 23 in relation to the
member 25, it is possible to achieve the feature whereby the member
25 becomes caught by the next oncoming tooth upon release by any
given tooth. Thus, when the member 25 becomes released by any given
tooth when the latter moves in the direction opposite to that of
the shown arrow, and the member 25 proceeds thereafter to snap back
to initial position, a member 25 becomes caught by the next
oncoming tooth. As a result of this action, the contacts 27 and 28
are prevented from coming into electrical contact with each other
when the member 25 snaps back upon release of the intercepting
tooth of the segment 23. With this arrangement, therefore, it is
possible to achieve the feature whereby enrichment pulses are
generated through closure of the contacts 27 and 28, only when the
throttle is being opened.
A third embodiment of the present invention is shown in FIGS. 4 to
6. In this embodiment, the throttle flap 32 is mounted upon a
carrying shaft 33. A bearing member 34 is held to the shaft 33,
through means of a leaf spring 35 pressing against a flattened
portion or zone 36 on the shaft 33. An intercepting or gripping
nose 37 is secured to the bridge 34. This intercepting member 37
reaches freely into a recess portion 38 of an insulating disc 39.
The insulating plate 39 carries two closely located contact members
40 and 41, which extend angularly beneath the plate. The upper
portion of these contact members 40 and 41 terminate into two
contact springs 42 and 43 facing towards the bearing member 34. In
the vicinity of their free ends, the contact springs are provided
with two contacts 44 and 45. An insulating member 48 is secured to
a carrying arm 47 located diametrically opposite to the
intercepting or nose member 37. The insulating member 48 is mounted
at the height of the contact springs. The insulating member 48
forms, together with the two contacts 44 and 45, a drag switch 50
which becomes closed as a result of the insulating member 48 riding
upon the contact spring 42. Such closing action of the insulating
member 48 is realized when the throttle flap 32 swings or rotates
in the direction of the arrow A. In this direction of the flap 32,
the throttle becomes opened. The necessary contact pressure is
realized through a carrying hub 54 which serves as a brake. The hub
54 of the insulating plate 39 has a notch surrounded by a spring
clamp member 51 which, in turn, has a lug slided over a pin member
52 seated in the base plate 53 of the pulse generator. This base
plate carries to leaf springs 55 and 56 which are insulated from
each other, and which are provided with contacts 57 and 58 at their
free ends. In the idling position of the engine, corresponding to
the closed position of the throttle flap 32, the contacts 57 and 58
are retained in closed circuit position through the insulating
member 48 bearing or pressing against the oppositely lying leaf
spring 55. When, once the throttle flap is moved from its idling
position, the contacts become open or are transferred to circuit
open position. The open circuit state of the contacts 57 and 58 is
realized as soon as the throttle flap is moved only by a small
amount from its idling position. For the purpose of adjusting the
opening point of the contacts to the optimum location of this
idling switch in relation to the throttle flap 32, elongated slots
59 are situated concentrically with respect to the axis of the
throttle shaft 33. By passing bolts through these elongated slots
59, the base plate 53 may be adjusted in position and secured to a
casting 60 on the intake manifold 31.
Three contact tracks 61, 62, and 63 are deposited upon a nylon
plate 65, concentric with the rotational axis of the throttle shaft
33. These contact tracks are provided for the purpose of producing
enrichment pulses during the opening of the throttle flap, and are
provided in addition to the two contact members 40 and 41 of the
drag switch. The contact member 41 may slide along the inner
contact track 61, when the insulating plate 39 together with the
throttle flap 32 is rotated into opening position of the latter.
The second contact member 40 is thereby alternatingly brought into
contact with one or the other of the two exterior or outer contact
track 62 and 63. These two contact tracks are designed so that each
has nine cross-stages 66 and 67, which is greater than the number
shown in the drawing. Thus, each of the tracks 62 and 63 is
provided with transverse portions 66 and 67, respectively, which
interleaf alternatingly. The contact member 40, therefore, will
contact the portions 66 and 67 in an alternating manner and thereby
provide the required number of pulses. The larger the number of
these transverse portions or cross-stages 66 and 67, the more
sensitive is the pulse generator for small opening motions of the
throttle flap. An advantageous design is realized when the spaces
or gaps between neighboring cross-stages or transverse portions 66
and 67 are larger than the contact surface 68 in the sliding
direction across these transverse portions 66 and 67. In this
manner, unintended oscillations of the gas pedal resulting from
small vibrations of the motor vehicle and produced by the driver,
do not result in the emission of signals.
For the purpose of avoiding error problems, the outer contact track
63 may, as described in a practical example below, be connected to
one of two inputs of a bistable transistorized multivibrator. The
central contact track 62, at the same time, may be connected to the
second input of the multivibrator, and the inner contact track 61
may, for example, be connected to ground potential so as to form a
switching arrangement. In this arrangement, the multivibrator
becomes switched in state not when the contact finger or member
leads a cross-stage or transverse portion, but instead the
multivibrator first changes state when the contact finger or
contact member moves onto a neighboring transverse portion or
cross-stage to which the other multivibrator input is
connected.
The drag switch 50 opens in the closing direction of the throttle
flap 32 and as a result of the rotational action between the nose
portion 37 and the cross section 38. This state of the drag switch
50 in which it opens, takes place before the insulating plate 39
can follow with the insulating member 48 and the bearing member 34.
The insulating plate 39 is braked from the spring clamp 51. As a
result of this action, enrichment pulses are generated only during
the opening of the throttle flap or valve. The generation of such
enrichment pulses, on the other hand, is suppressed in the closing
direction of the throttle valve, through the contacts 44 and 45 of
the drag switch, which are then in the open state.
The injection arrangement in accordance with FIG. 7 of the present
invention, is designed for operation in conjunction with a remotely
ignited four-cylinder, four-cycle internal combustion engine. This
fuel injection arrangement shows a preferred embodiment for the
signal generator of FIGS. 4 to 6. Four electromagnetically actuated
injection valves are associated with the injection arrangement. Two
of these valves 110 and 120 inject simultaneously. Assume that the
internal combustion engine has a I-IV-III-II ignition sequence. In
that case, the electromagnetically operated valves of the first and
fourth cylinder belong to the first valve group 110, whereas the
electromagnetically operated valves for the third and second
cylinder belong to the valve group 120. Thus, the coils 110 and 120
each represent diagrammatically groups of electromagnetically
operated valves. The fuel injected by the electromagnetically
operated valves of the two groups 110 and 120, is applied to the
valves by an electrically operated pump which maintains the
pressure constant at two atmospheres.
A PNP power transistor 111 is associated with the valve group 110,
whereas the power transistor 121 is associated with the valve group
120. These two power transistors 111 and 121 are driven by driving
transistors 112 and 122, respectively. The combination of the
transistors 112 and 111 form an end stage 113, whereas the
transistors 121 and 122 form a second end stage 123.
The injection valve groups must be brought alternatingly into their
open positions in relation to the crankshaft rotation of the
engine. This feature is accomplished through two switches 101 and
102 arranged in an ignition distributor, not shown. These two
switches are operated through cams which have actuating portions
displaced 180.degree. from each other. Accordingly, the switches
101 and 102 are closed through these cams at 180.degree.
displacements. The two switches operate in conjunction with a
bistable multivibrator 130 which includes two NPN transistors 131
and 132. The emitters of these two transistors are both joined to
the negative voltage supply line 100. Each of the collectors of
these two transistors lead to the positive supply line 90 through a
separate resistor. Thus, the collector of the transistor 131 leads
to the supply line by way of resistor 133, whereas the collector of
132 is associated with the resistor 134. Furthermore, the base of
transistor 131 is connected to the collector of transistor 132
through a feedback-coupling resistor 135. Such a similar feedback
resistor 136 is connected between the base of the transistor 132
and the collector of transistor 131. Of the two transistors 131 and
132, that one is in nonconducting state, which is associated with
the switch that was previously closed and which is connected in
parallel with the emitter-base path of the transistor. This
transistor then remains in this cutoff or turned-off state until
the other switch associated with the other transistor becomes
closed through the further operation of the cam. The switches 101
and 102 do not determine, however, the duration of the injection
processes of the valve groups 110 and 120. These switches, instead,
are criteria for establishing when and which of the two groups or
valves are to be brought in their opening position. The quantity of
fuel injected into the intake manifold of the engine during each
injection process, is proportional to the duration of
rectangular-shaped control signals. These control signals are
produced at the output of a control multivibrator 150 which is
shown in the drawing in considerably simplified form. The pulse
signals are produced for each closure of the switch 101 and 102.
The control multivibrator includes an input transistor 151 and a
transistor 152 which is an output transistor with base-connected to
the collector of the transistor 151. The two transistors are of the
NPN type. In the control multivibrator 150, which is shown in
illustrative form, a transformer 153 is provided for the purpose of
matching or fitting the duration of the control pulses. This
transformer 153 in the form of an inductive timing element, has a
primary winding 154 connected in series with a resistor 155. The
series combination of these two elements 154 and 155, is connected
between the collector of the transistor 152 and the positive
voltage supply line 90. The primary winding 154 is coupled to the
secondary winding 156 through an adjustable ferromagnetic core 157.
The circuit arrangement is such that through this transformer, the
collector of the transistor 152 is coupled to the base of the
transistor 151. The adjustable ferromagnetic core 157 is connected
through mechanical linkage, to a pressure-sensing membrane located
within the intake manifold and behind the throttle flap of the
engine in the intake direction. When the pressure prevailing within
the intake manifold drops, so that the absolute pressure decreases,
the adjustable core 157 is drawn from the transformer, by
predetermined amounts, to thereby reduce the inductance of the
transformer.
The base of the transistor 151 is connected to the collector of the
transistor 132 of the signal generator 130 through a decoupling
diode 159 and a capacitor 144. A similar decoupling diode 158 and
capacitor 145 is connected between the base of the transistor 151
and the collector of the transistor 131. The capacitors 144 and 145
serve as differentiating elements. These differentiating elements
reside within the differentiating circuits 140 in which resistors
141 and 142 are connected to the negative voltage supply line 100.
The resistor 141 is connected to the capacitor 145, whereas the
resistor 142 is associated similarly with the capacitor 144. For
every closure of the switch 102, a signal 146, as shown in the
drawing, is realized for the control multivibrator 150. The signal
results through the condition that the transistor 131 becomes
conducting and the base potential of the input transistor 151
becomes negative in relation to the negative supply line 100 as a
result of the previous turned-off state of the transistor 131 and
the charge of the capacitor 145 through the diode 158. This
negative potential of the base of the transistor 151 is such that
the input transistor which was turned on to that instant, becomes
turned off and, at the same time, the turned-off output transistor
becomes turned on. The collector current of the output transistor
associated with the primary winding 154 of the transformer 153,
then produces a feedback voltage signal within the secondary
winding 156. This voltage signal within the secondary winding 156
retains the input transistor 151 turned off through the transition
interval. The input transistor 151 is, in fact, held turned off
until the voltage has dropped to a minimum value determined by the
setting of two resistors 161 and 162 connected to form a voltage
divider. The input transistor 151 then returns to its stable
conducting state and, at the same time, turns off the output
transistor 152.
A logical AND gate 115 is connected in front of the power stage
113, while a similar AND gate 125 is connected in front of the
power stage 123. These AND gates assure that the control pulses
initiated through the closure of the switches 101 and 102 become
selectively applied to the valve groups 110 and 120. The AND gate
115 has an NPN transistor 116 which has its base connected to the
collector of the signal generator transistor 132, by way of the
base resistor 117 and the conducting path 118. The AND gate 125, on
the other hand, has a transistor 126 with base connected to a
resistor 127 leading to the collector of the transistor 131 by way
of the conducting path 128. The transistors 131 and 132 are
associated with the signal generator 130. The bases of the two
transistors 116 and 126, furthermore, are connected by way of
second base resistors 119 and 129, respectively, to the collector
of a further transistor 163. The base of the transistor 163 is
connected to a noncrucial stage 170, so that the transistor becomes
turned off in the interval between two of the pulses delivered by
the control multivibrator 150. The transistor 163, however, will
turn off or cut off only that one of the AND gates 115 and 125
which also has, at the same time, the respective one of the
transistors 131 and 132 in the conducting state. The AND gate which
is operated in this manner, then cuts off the injection process of
the respective valve groups 110 and 120.
In operation of the circuitry with relation to the timing diagram
shown in FIG. 8, the switch 102 becomes closed at the time instant
t.sub.1. The transistor 132 is then transferred to its turned-off
state, whereas the other transistor 131 becomes conducting. The AND
gate 125 is thereby brought into its switched-off state in
conjunction with the simultaneously delivered control pulses from
the multivibrator 150. The AND gate 125 maintains this switched-off
state until the termination of the control pulse delivered by the
control multivibrator 150. In this switched-off state of the AND
gate 125, the power stage 123 is held in the conducting state for
producing an opening pulse for the valve group 120. As soon as the
control pulse is terminated at the instant t.sub.2, the transistor
163 turns to its turned-off state and terminates the injection
process through turning off the power stage 123. This operational
sequence takes place even though an opening signal for the valve
group 120 prevails at the AND gate 125 until the final instant of
time t.sub.11 of the switch 101. Such opening pulse is not,
however, effective since the transistor 131 as well as the
transistor 163 would have to be both conducting.
The next injection process is initiated at the valve group 110 at
the instant t.sub.11 through the then closing switch 101. The
transistor 132 thereby transfers to the conducting state and the
input transistor 151 of the multivibrator 150, moreover, becomes
turned off through the differentiating capacitor 144 for the
duration of the next control pulse determined by the position of
the ferromagnetic core 157. The injection process for the valve
group 110 becomes terminated with the expiration of the control
pulse at the instant t.sub.12. The next injection process can then
result through an injection arrangement which is constructed
similar to that already described, by closure of the switch 102 at
the instant t.sub.21.
The two AND gates 115 and 125 operate, in conjunction with the
bistable signal generator 130, in the form of an electronic
distributor. They make possible to drive the fuel injection
arrangement such that enrichment pulses are applied for
acceleration purposes when the throttle flap is moved towards or
into the opening direction. This is in conjunction with the
injection processes resulting synchronously with the rotations of
the crankshaft, and the injection pulses are inserted in the form
of intermediate pulses. For the purpose of realizing a number of
control signals which is proportional to the opening path of the
throttle flap, a pulse generator is designed as shown in FIGS. 4 to
6. The contact springs of a switch functioning as a drag switch are
designated by the two contacts 44 and 45. One of these contacts is
connected to the negative voltage line 100, whereas the other one
is connected to the contact finger or spring 40 which is shown
schematically in FIG. 7 as a switching on. This contact spring 40
rides over the cross-stages 66 and 67 during the opening motion of
the throttle flap, and thereby makes contact alternatingly and in a
rapid manner with the two outer contact tracks 62 and 63.
The two outer contact tracks 62 and 63 are applied to the bases,
respectively, of the transistors 232 and 231 which are associated
with a second bistable multivibrator 230. This multivibrator is
constructed similarly to the signal emitter or generator 130. This
multivibrator differs from the former unit 130, however, in that it
will change rapidly between its stable states only when the contact
tracks 62 and 63 are brought rapidly into connection with the
negative voltage supply line 100 while the drag switch is closed,
and during the opening movement of the throttle flap.
In the diagram of FIG. 8, it is assumed that at the instant of time
t.sub.3, the throttle flap becomes opened from its previous
stationary opening angle .alpha., of approximately 25.degree. for a
rotational speed n=2000 revolutions per minute of the engine. The
throttle flap becomes opened from this stationary angle within one
twentieth sec. =50 m. sec. corresponding to approximately
45.degree.. The contact fingers or springs thereby ride over the
cross-stages 66 and 67 with essentially constant velocity. Thus,
during this opening movement of the throttle flap, the contact
springs transverse nine times one of the cross-stages 66 and 67.
The bistable multivibrator 230 is thereby brought to its opposite
stable state.
Capacitors 244 and 245 are connected, respectively, to two diodes
248 and 249. These capacitors form differentiating circuits with
the respective resistors 241 and 242, similar to the
differentiating circuits 140 described above. These differentiating
circuits are connected through one electrode of the capacitors 244
and 245, to the collectors, respectively, of the transistors 231
and 232. These two transistors are associated with a monostable
multivibrator 250. This monostable multivibrator delivers an
intermediate pulse Z of approximately 2.2 milliseconds for every
transfer of state or switching process of the bistable
multivibrator.
Referring to FIG. 8, the first intermediate pulse begins at the
commencement of the opening motion of the throttle flap at the
instant of time t.sub.3. The second intermediate pulse is generated
or appears 6 milliseconds later at the instant of time t.sub.4. For
the purpose of generating this intermediate impulse Z at
substantially constant pulse duration, the base of the transistor
251 leads to the positive supply line 90, through a diode 259 and
resistor 258. The collector of this transistor 251 is, furthermore,
connected through a coupling resistor to the base of an NPN type of
transistor 252. The collector of this transistor 252 is coupled to
the base of the transistor 251 through a timing capacitor 257 of
approximately 0.07.mu.f. In the quiescent state, the input
transistor 251 is conducting and maintains the transistor 252
turned off. The input transistor 251, however, is turned off
through the charge upon the differentiating capacitor 244 or 245 as
soon as the bistable multivibrator 230 switches states, as a result
of contact finger 30 riding upon the next cross-stage or transverse
portion of the contact tracks. The input transistor 251 is
maintained in this turned-off state for the duration of the
intermediate pulse Z, and until the charge upon the capacitor 257
has become equalized through the resistor 258 and the collector
resistor 255 of the second transistor 252.
The aforementioned transistor 163 is arranged in the form of an OR
element 165 so that the intermediate pulse Z may be applied to one
of the two valve groups 110 or 120 for additional injection
processes. The base of the transistor 163 is connected, on one
hand, to the intermediate stage 170, through the resistor 166. At
the same time, the base of this transistor 163 is connected to the
collector of the transistor 251, through the resistor 168. A third
resistor 167 is connected between the base of this transistor 163
and the negative voltage supply line 100. This resistor 167 assures
that the transistor 163 remains turned off for as long as either an
intermediate pulse Z lies at its base, or a control pulse J derived
from the monostable multivibrator 250 or from the control
multivibrator 150 by way of the intermediate stage 170. As soon and
for as long a control pulse is realized from one of these two
control pulse sources, the OR gate 165 is in the conducting state,
and permits an injection process to be carried out through the end
stage selected by the signal generator 130 and the corresponding
valve group. The injection process takes place during the duration
of these control pulses. As shown in FIG. 8 for the instant of time
t.sub.20, such an injection process can prevail beyond the end of
an individual control pulse, when two control pulses J and Z
overlap only partially.
The second fuel injection arrangement of FIG. 9 differs principally
from the first injection arrangement described above, through the
condition that the acceleration enrichment fuel quantity is
realized on the basis of the intermediate pulses Z as well as
through normal pulses J.sub.n generated synchronously with the
rotations of the crankshaft of the engine. These normal pulses
J.sub.n may be extended in duration over a widely varying factor. A
multiplying stage 300 is provided here in place of the stage 170
behind the control multivibrator 150 in FIG. 7. This multiplying
stage 300 includes an intermediate transistor 310 of NPN type, as
well as two transistors 301 and 302 of PNP type. A further
transistor 303 also within the multiplying stage 300 is of the NPN
type. The emitter of the transistor 301 is connected to the
positive voltage line 90, through a resistor 304. One electrode of
a storage capacitor 305 is connected to the collector of this
transistor 301. The other electrode of the storage capacitor 305 is
connected to the base of the transistor 303, as well as the
collector of the transistor 302. The base of the transistor 302 is
joined to a junction or tap of a voltage divider consisting of
resistors 306 and 307. The emitter of the transistor 302, on the
other hand, is joined to the positive voltage supply line 90, by
way of the resistor 308. The emitter of the output transistor 303
of the multiplying stage 300, is connected to the negative voltage
supply line 100, whereas the collector of this transistor 303
leads, by way of the resistor 309, to the positive voltage supply
line 90. At the same time, this collector of the output transistor
303 is joined to one input of an OR gate 165 which may be of the
design derived from FIG. 7. In this regard, the transistor 163 may
be thought to be connected with the collector of the transistor 303
through a coupling resistor designated as 166 in FIG. 7.
The intermediate transistor 310 is connected through its base to
the collector of the transistor 152 associated with the control
multivibrator 150. The collector of the intermediate transistor 310
leads to the positive voltage supply line 90, by way of a resistor
312. At the same time, the collector of the transistor 310 is also
connected to an input of the OR gate 165, through the resistor 311.
This connection may be termed to be the base of the transistor 163.
The second coupling resistance which leads to the transistor 163
belonging to the OR gate 165, as shown in FIG. 7, leads also to the
collector of the transistor 251 in FIG. 9. This transistor 251
belongs to the monostable multivibrator 250 which supplies
additional pulses Z.
The monostable multivibrator 250 is actuated in a manner similar to
the injection arrangement of FIG. 7. Thus, the monostable
multivibrator is actuated through the bistable multivibrator 230
and through intermediate differentiating elements 240. As a result
of the opening motion of the throttle flap of the engine, a series
of intermediate pulses Z are generated from the cross-stages by the
contact track 62 and 63 which are traversed by contact springs 40.
These pulses Z are shown in FIG. 10 through six pulses in the
waveform designated IV. In contrast to the arrangement of FIG. 7,
different elements lie between the junction A of the monostable
control multivibrator 250 of FIG. 9. Thus, connected to the
junction A, is a capacitor 257 which serves as a timing element, a
resistor 255 associated with the transistor 252, and a diode 258
connected directly to the collector of this transistor 252.
Connected also to the collector of the transistor 252 is a series
circuit including the resistor 261, diode 262 and capacitor 263.
The collector of the transistor 252 leads to the positive supply
line 90 through this series circuit combination.
The base of a PNP transistor 265 is connected to the junction of
the diode 262 and capacitor 263. A resistor 264 is connected in
parallel with the capacitor 263. This transistor 265 functions as
an emitter follower through the connection of the resistor 266
between the emitter of this transistor and the positive voltage
supply line 90. The detailed functional operation of the
multiplying stage 300 in conjunction with the intermediate pulses Z
delivered by the monostable multivibrator 250 may be described as
follows:
The transistor 252 is turned on in the monostable multivibrator 250
for the duration of the intermediate pulse Z. During each one of
these intermediate pulses, the capacitor 263 may become charged in
the base circuit of the transistor 265. As a result of such
charging, the voltage U.sub.c across the capacitor 263 increases.
The resistor 261 lying in the charging circuit is selected with low
ohmic value compared to the resistor 264 lying in the discharge
circuit of the storage capacitor 263, so that the voltage U.sub.c
achieves the maximum charging potential prevailing between the two
resistors 267 and 268, after three intermediate pulses Z. The two
resistors 267 and 268 belong to the voltage divider. The base of
the transistor 265 follows the function or waveform of the
capacitor voltage U.sub.c. A current i.sub.2 is applied to the
collector of the transistor 265, which corresponds to the capacitor
voltage. This current is applied through the emitter resistor 266.
This current i.sub.2 is also applied additionally as charging
current to the storage capacitor 305 within the multiplying stage
300.
For the purpose of understanding the function of the additional
charging current i.sub.2, it is essential to consider next the
functional operation of the multiplying stage 300 during stationary
operation of the internal combustion engine. Assume, for example,
that at the instant of time t.sub.1, one of the switches 101 and
102 of the signal generator 130, becomes closed through the action
of the cam which operates the switch. In that case, the output
transistor 152 of the control multivibrator 150 is transferred to
the conducting state for the duration of the control pulse J.sub.s.
As a result, the intermediate transistor 310 becomes turned off,
and the input transistor 301 can deliver a practically constant
charging current i.sub.1 to the storage capacitor 305. The input
transistor 1301 accomplishes such constant charging current during
the interval of the control pulses J.sub.s, and through the voltage
divider consisting of resistors 311 and 312. The voltage U.sub.1
across the capacitor 305 increases proportionally with time as
shown to the left of the waveform II in FIG. 10. For the duration
of these control pulses, the OR gate 165 may be maintained
conducting, through the resistor 311. As soon as the control as the
control pulse J.sub.s terminates at the instant of time t.sub.2,
the intermediate transistor 310 returns to its original conducting
state. As a result, the capacitor 305 has the potential of the
negative voltage supply line 100 applied to it, through the
base-collector path of the input transistor 301. Through the charge
stored on the capacitor 305, the output transistor 303 becomes
turned off and remains in this turned-off state until the instant
of time t.sub.2 . At that instant of time, the constant charging
current delivered by the transistor 302 has equalized the charge
and thereby allows the transistor 303 to return to its original
conducting state. The OR gate 165 remains further conducting during
the time interval t.sub.2 to t.sub.2 corresponding to the cutoff
interval of the output transistor 303. This is due to the condition
that the transistor 163 of the OR gate 165 receives base current
through the resistor 309. In the example described, the discharge
current of the storage capacitor 305 is precisely as large as the
charging current i.sub.1 flowing through the input transistor 301.
As a result, the duration of the normal pulses J.sub.n for the
injection process, is twice as large as the duration of control
pulses J.sub.s realized from the control multivibrator 150.
A multiplying stage which is shown in FIG. 9 in simplified form, is
independent of the operation of the present invention. It is of
particular importance when only a portion of the control
multivibrator takes into account varying operating conditions
during the operation of the internal combustion engine. One such
varying condition or parameter is, for example, the introduction of
larger quantities of fuel for every cycle of the engine when the
latter is not, as yet, warm. Such larger quantities of fuel are
required when the engine is cold and is in the process of being
heated. After the engine has been heated through operation, the
amount of fuel can be reduced.
As may be seen from FIG. 10, the multiplication factor from the
multiplying stage 300 is larger with increase in the charging
current i.sub.1. From this possibility, use is made of extending
multiplicatively the normal pulses J.sub.n for the injection
arrangement of FIG. 9. For the next charging process of the storage
capacitor 305 of the multiplying stage 300, at the instant of time
t.sub.11, charging current i.sub.1 is realized additionally from
the input transistor 301. At the same time, the transistor 265
supplies further charging current i.sub.2. As a result of the three
intermediate pulses Z generated through the throttle flap pulse
generator, the charging current i.sub.2 may have considerable
magnitude. This is because the voltage U.sub.c of the capacitor 263
may already have attained approximately its maximum value.
Through the combined effect of the two charging currents i.sub.1
and i.sub.2, an essentially rapid voltage rise appears across the
capacitor 305 from the time instant t.sub.11. When the discharge
current remains unchanged, an extension of the injection process
results. A larger amount of fuel is thereby injected which is
represented in the diagram through crosshatching. The capacitor 263
has a discharge time constant of approximately 1 second, by being
of the order of 10 .mu.f., and its voltage U.sub.c decays thereby
very slowly. This conditions results in an extension of the
subsequent normal pulses, when the opening motion of the throttle
flap is terminated after six intermediate pulses Z, in the
illustrative example. A stepless transition of the normal pulse to
greater length is thereby realized. Such greater pulse length is
required for higher rotational speeds of the engine and after
termination of the acceleration process due to increase in the air
pressure within the intake manifold, the extension or lengthening
of the normal pulses may be realized through the control
multivibrator 150 alone, or in conjunction with further elements
depending upon the rotational speed of the engine and not shown in
the drawing.
FIG. 9 shows in broken lines a circuit arrangement which allows the
intermediate pulses provided by the monostable multivibrator 250,
to be shortened in duration when the number of these pulses
increases. This circuit arrangement is shown within the monostable
multivibrator 250. The function of such shortening of the pulses is
illustrated in the waveform VI in FIG. 10. This circuit arrangement
for shortening the intermediate pulses, consists of a resistor 254
of approximately 150 kohm connected in parallel with a capacitor
253 having a capacitance of the order of 2.2 .mu.f. This capacitor
becomes charged from the conducting transistor 252, similar to the
capacitor 263 during the presence of the intermediate pulses Z.
Within the interval between two successive intermediate pulses Z,
the capacitor 257 within the feedback circuit of the monostable
multivibrator 250, can become charged only to the potential
U.sub.3. This capacitor 257 serves as a timing element. The
potential U.sub.3 corresponds to the potential difference between
the junction A and the base of the conducting input transistor
251.
The voltage U.sub.3 becomes smaller as shown in FIG. 10, and
thereby the length or duration of the intermediate pulses Z'
becomes shorter, the greater the number of intermediate pulses
generated. The intermediate pulses Z' are formed through the
unstable state of a monostable multivibrator 250. Such shortening
of the duration of the pulses also occurs with increased frequency
of the intermediate pulses as generated by the pulse generator and
the bistable multivibrator 230.
In the injection arrangement of FIG. 9, the individual end stages
in the form of AND gates 115 and 125 determine cooperatively with
the bistable multivibrator 130, which one of the two valve groups
110 and 120 is to made effective through the intermediate pulses Z
or Z'.
For specific types of internal combustion engines, it may be of
advantage to apply alternatingly to the valve groups only the
normal pulses J.sub.n generated synchronously with the crankshaft
rotation. At the same time, the intermediate pulses Z and Z' are
used for auxiliary injection processes simultaneously at the two
valve groups. In this regard, the injection arrangement shown in
FIG. 9 can be easily modified so that the two interconnected inputs
of the two AND gates 115 and 125 are directly coupled to the output
of the multiplying stage 300. Instead of the OR gate 165, one of
two OR gates is inserted between each AND gate and its end stage.
These two OR gates are connected with one of their two inputs, to
the collector of the transistor 251, whereas the other input is
connected to the output of the AND gate 115 or the AND gate
125.
From the diagram of FIG. 10 it may be seen that the first
intermediate pulse appearing at the time instant t.sub.3, and the
fourth intermediate pulse which appears at the time instant
t.sub.6, fall within the normal pulse J.sub.n. These pulses,
thereby, become lost from the viewpoint of acceleration enrichment,
notwithstanding their contribution to the formation of the
capacitor voltage U.sub.c.
In the injection arrangement of FIG. 11, means is provided that
such intermediate pulses which are completely overlapped from the
normal pulses J.sub.n, are first introduced into a storage and
become then attached to the end of the overlapping normal pulse.
For this purpose, one of the two inputs of the OR gate 165 is
connected to the collector of the output transistor 303 of the
multiplying stage 300. The second input is connected, as shown in
FIG. 9, to the intermediate transistor 310, by way of the resistor
311. Instead of the multivibrator 250 used in the injection
arrangement of FIGS. 7 and 9, a switching element is connected to
the two differentiating circuits 240, through both of the diodes
248 and 249. This switching element or circuit portion also
functions as an electronic storage or electronic logical element in
conjunction with the two AND gates 115 and 125, and provides
moreover, the function of the bistable multivibrator 250.
In particular, this circuit contains an NPN transistor 271 and a
second NPN transistor 272 with its base connected to the collector
of the transistor 271. Both of the emitters of these two
transistors are connected to the negative voltage supply line 100.
The collectors of the two transistors lead, respectively, to the
positive supply line 90, by way of the resistors 273 and 274. A
resistor 270 is, furthermore, connected between the base of the
transistor 271 and the negative voltage supply line 100. Oppositely
directed diodes 275 and 249 are connected, at the same time, in
series with the base circuit of the transistor 271. The diode 248
directed identical to that of diode 249 is joined to the junction
of the diodes 275 and 249. The cathodes of two additional diodes
276 and 278 are also joined to the junction between the diodes 249
and 275. A resistor 277 is connected between the anode of the diode
278 and the collector of a PNP transistor 281. A resistor 279 is
connected in series with the diode 276 and is, at the same time,
connected to the collector of the transistor 272. The collector of
the transistor 272 is joined to a feedback coupling capacitor 282
which is connected between this collector of the transistor 272 and
the junction D between the diode 278 and the resistor 277. Through
this design which includes the feedback capacitor 282, the
transistor 272 functions together with the transistor 271 in the
form of a monostable multivibrator circuit similar to the
monostable multivibrator 250 through which intermediate pulses Z
are produced as described in the preceding injection arrangement,
by way of the throttle flap pulse generator, the bistable
multivibrator 230 and the differentiating elements 240.
In contrast to the first one of the two injection arrangements
shown in FIG. 7 and FIG. 9, the output of the OR gate 165 is not
directly coupled to the two AND gates 115 and 125. The first input
of the two AND gates 115 and 125 each leads to the signal generator
130, by way of the connecting path 118 and 128, respectively. The
other inputs of the AND gates 115 and 125 are decoupled from each
other through the respective series circuits consisting of the
diode 283 and resistor 284, and the diode 285 connected in series
with the resistor 286. The two resistors 284 and 286 are joined at
a common connection, and the output of the OR gate 165 is also
joined to this common connection, through the resistor 287. The
anode of a diode 288, furthermore, is also connected to this
junction G of the resistors 284, 286 and 287. The cathode of the
diode 288 is connected to the collector of the transistor 272. The
circuit also includes a further transistor 290 of the PNP type. The
emitter of this transistor 290 is directly connected to the
negative voltage supply line 100, whereas the base of the
transistor 290 leads to the output of the OR gate 165, by way of
the resistor 291. Thus, the output of the OR gate 165 feeds to the
resistors 287 and 291. Connected to the collector of the transistor
290, are two resistors 292 and 293. The resistor 292 leads directly
to the positive voltage supply line 90, whereas the resistor 293
leads to the base of the transistor 281 which is PNP transistor.
The circuit constructed of the elements 270 to 293 operates in
accordance with the waveform diagram of FIG. 2, in the following
manner:
The pulse generator 130 transmits normal pulses synchronously with
the rotation of the crankshaft of the internal combustion engine.
These normal pulses appear at the output C of the OR gate 165, and
this output signal of the OR gate will be designated at negative
potential in the description below. The output signal of the OR
gate 165 is only a few tenths of a volt above the potential of the
negative voltage supply line 100. Each of the two AND gates 115 and
125 can transfer its respective end stage to the conducting state
only when both of its inputs are at negative potential.
Accordingly, an injection process can take place only when the
junction G is at negative potential. This is, however, also the
case with the aforementioned normal pulses, for as long as the
transistor 272 is in the conducting state. The transistor 290 which
serves to drive the PNP transistor 281, is maintained in the
conducting state over the resistor 291, provided that no signal
appears at the output C of the OR gate 165. Base current for the
transistor 281 can then flow through the resistor 293, so that the
transistor 281 may become conducting. In this turned-on state of
the transistor 281, base current is applied to the transistor 271
through the resistor 277 and the diode 278. The transistor 271
thereby conducts during the intervals between two normal pulses,
whereas the transistor 272 which is directly coupled to the
transistor 271, is turned off. As soon as a negative potential
appears at the output C, at the beginning of a normal pulse, the
transistor 290 is turned off and the transistor 281 is consequently
also turned off. As a result, no current can flow over the resistor
277, for the transistor 271. When the switching stage consisting of
transistors 271, 272 and 281 has not, as yet, been actuated by the
transfer in states of the bistable multivibrator 230, at for
example the instant t.sub.2 in FIG. 12, then this unactuated
switching stage remains in its quiescent state. In this quiescent
state, the transistor 272 is turned off, whereas the transistor 271
is turned on as a result of the base current flowing through the
resistor 279, the diode 276 and the diode 275.
If, however, in accordance with the uppermost curve in FIG. 12 and
at the instant of time t.sub.3, the monostable multivibrator 230
becomes actuated as a result of the contact finger 40 of the pulse
generator shown in FIGS. 4 to 6, rides upon the next cross-stage 66
or 67, a turning-off signal for the transistor 271 will appear
through the differentiating elements 240. As a result, the
transistor 272 can transfer to its connecting state. As shown in
the next to the last curve in FIG. 12, the junction G acquires
negative potential for the time interval of the now following
intermediate pulses Z. For as long as no normal pulse appears, as
illustrated for the time interval between t.sub.2 and t.sub.11 in
FIG. 12, the transistor 281 is in the conducting state.
Accordingly, the capacitor 282 which functions as the timing
element for the intermediate pulses, may become charged through the
resistor 277. The capacitor 282 may acquire such charge until the
transistor 271 becomes again conducting. A voltage function is then
realized at the junction D, as illustrated in the third diagram
over and beneath the time axis t for both of the first intermediate
pulses J which appear at the time instant t.sub.3 and t.sub.4.
A third emission of an intermediate pulse results at the time
instant t.sub.5. At that time, however, the normal pulse emitted at
instant t.sub.11 is in effect. A prevailing normal pulse has the
characteristics, in accordance with the above-described features,
that the transistor 290 and 281 become cut off. At the instant of
time t.sub.5, the transistor 271 becomes turned off through the
signal transmitted from the differentiated stage 240, and the
transistor 272 is consequently turned on. The resulting step
voltage appearing at the transistor 272 is then transmitted to the
base of the transistor 271. Charging of the capacitor 282 can then
first take place, when the transistor 281 is turned on. This
corresponds to the time after the instant t.sub.12, during which
the normal pulses from the OR gate 165 and synchronized with the
engine speed, are terminated. The junction D has, thereby, a rising
potential after the time instant t.sub.12, since charging of the
capacitor 282 is now possible through the resistor 277 and the
conducting transistor 281. After the interval of the intermediate
pulse, designated as t.sub.z, the transistor 272 returns to its
stable turned-off state. The intermediate pulse initiated at the
time instant t.sub.5, therefore, does not become lost for purposes
of fuel enrichment. Instead, this pulse becomes attached to the end
of the normal pulses generated synchronously with the crankshaft
rotation of the engine.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of constructions differing from the types described
above.
While the invention has been illustrated and described as embodied
in a fuel injection arrangement, it is not intended to be limited
to the details shown, since various modifications and structural
changes may be made without departing in any way from the spirit of
the present invention .
* * * * *