GB1587705A

GB1587705A - Control apparatus for limiting the maximum quantity of fuel to be injected in an internal combustion engine

Info

Publication number: GB1587705A
Application number: GB1840678A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-01-05
Filing date: 1978-05-09
Publication date: 1981-04-08
Also published as: DE2800434A1

Description

(54) A CONTROL APPARATUS FOR LIMITING THE MAXIMUM QUANTITY OF FUEL TO BE INJECTED IN AN INTERNAL COMBUSTION ENGINE (71) We, ROBERT BOSCH GmbH of 7000 Stuttgart 1, Postfach 50, Federal Republic of Germany, a limited liability company organised under the laws of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a control apparatus for limiting the maximum quantity of fuel to be injected in an internal combustion engine.

In a known control equipment a pressuredependent abutment is provided for the regulating rod. The abutment is displaced directly through a pressure cell.

It has been provided necessary that the travel of the regulating rod must be limited in dependence upon the combination of the most diverse operational characteristic magnitudes and operational states. The known control equipment does not offer this multiplicity of possibilities of action.

According to the present invention there is provided a control apparatus for limiting the maximum quantity of fuel to be injected in an internal combustion engine, the apparatus comprising a regulating member to determine the quantity of fuel to be injected, a regulating linkage connected with the regulating member, means responsive to the rotational speed of the internal combustion engine and coupled by means of the regulating linkage to the regulating member to control the position of the regulating member, a first abutment to limit displacement of the regulating member, the position of the first abutment relative to the regulating member being controllable in dependence upon the magnitude of operational characteristics of the internal combustion engine, and an error recognition circuit means arranged to receive a first signal indicative of the actual position of the first abutment and a second signal indicative of an intended position of the first abutment, and to provide an output signal in dependence upon the first and second signals.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows a control apparatus embodying the invention for limiting the maximum quantity of fuel to be injected by a hydraulic setting mechanism of an abutment dependent on operational characteristic magnitude Fig. 2 shows details of the mechanical part of the control apparatus shown in Fig. 1, Fig. 3 shows a block schematic diagram of the electrical drive associated with the control apparatus of Fig. 1, Fig. 4 shows pulse diagrams in connection with an error recognition circuit, Fig. 5 shows a block schematic diagram of the error recognition circuit, and Fig. 6 shows a control apparatus embodying the invention and provided with an electromechanical drive for an abutment dependent on operational characteristic magnitude for the regulating member travel.

Referring now to the drawings, a control apparatus or equipment for limiting the maximum quantity of fuel to be injected in the case of an internal combustion engine with self-ignition is drawn schematically in Fig. 1. A regulating rod 10 functioning as a quantity-determining member stands in connection directly with an injection pump (not shown). A rotational speed measuring mechanism 11 preferably with fly-weights, is driven through a shaft 12 and delivers the measured value in the form of a horizontal displacement of a sleeve 13 and a sliding block 13a. A regulating lever 14 with a gate control 15 is articulated to this sliding block 13a and this regulating lever 14 in turn stands in connection through an intermediate member 16 with the regulating rod 19.Guided in the gate 15 is a displacing lever 17, which in its rotational centre 18 stands in connection with a lever 19 and, also, indirectly through a spring member (not shown) with a drive pedal 20.

The intermediate member 16 is penetrated by an abutment bolt 21. The bolt 21 is provided with a first bolt part 22, which can enter into operative connection with an abutment 23. A second bolt part 24 can cooperate with an abutment 25, which is pivotable away. The abutment mounting 26 of the abutment 25 is provided with a groove 27, in which one side of the lever 19 is guided. The other side of this lever 19 is pressed by spring force against the sliding block 13a.

The displacement of the abutment 23 takes place by means of a spring-loaded hydraulic setting mechanism 30 having associated therewith a travel transmitter 31 to set the abutment 23. The abutment 25 stands in connection with a spring-loaded two-way valve 33. An electromagnetically actuable detent 34 holds the two-way valve 33 in its working position, i.e. with the spring loaded.

There is also provided a further two-way valve 35, a container 36 for liquid medium for loading the setting mechanism 30, and a pump 37 for for this medium.

The electrical circuitry of the control equipment for limiting the maximum quantity of fuel to be injected comprises an intended-value transmitter 40 with inputs for operational characteristic magnitudes such as rotational speeds, different temperatures and pressure. It delivers at its output 41 an intehded value for the position of the abutment 23 dependent on operational characteristic magnitude. This intended value is conducted to a comparator junction 42, at which the intended and actual value of the abutment position are compared and its output signal is fed to an error recognition circuit 44 and a regulator 45. The regulator 45 by its output signal feeds the electromagnetically actuable two-way valve 35.The output of the error recognition circuit is coupled by way of the electromagnet 46 for the actuation of the electromagnetic detent 34 to a junction point 47, which is connected directly with a voltage supply portion 48 and through a breakswitch 49 held in its rest position by means of spring force as well as through a current supply source 50 with this voltage supply portion 48.

In operation, the setting of the drive pedal 20 determines the setting of the displacing lever 17 and thereby the position of the regulating lever 14. A certain setting of the sleeve 13 is associated with each rotational speed, inter alia the shaft 12, and the position of the regulating rod 10 is thus also determined by way of the regulating lever 14 and intermediate member 16.

With the internal combustion engine at rest, the mass elements of the rotational speed measuring mechanism 11 assume a setting near the axis, whereby the sleeve 13 lies very far to the right. Since the stage 15 represents an axis for the regulating lever 14, the regulating rod 10 is arranged in start setting very far to the left. The lever 19 effects a pivoting-out of the abutment 25 with the internal combustion engine at rest, so that this abutment 25 does not co-operated with bolt part 24.

In the drawn setting of the two-way valves 33 and 35, the fuel pump 37 can convey pressure medium to the setting mechanism 30, whereby the abutment 23 dependent on operational characteristic magnitude is displaced to the right in the direction towards the abutment bolt 22. Should the position of the abutment 23 deviate from the intended position in the opposite sense then the regulator 45 switches over the electromagnetically actuable two-way valve 35; pressure medium can thus flow back out of the cylinder of the setting mechanism 30 into the container 36 and the abutment 23 displaces in consequence of the spring in the setting mechanism 30 to the left in the direction start. Should the intended-actual-value deviation exceed a certain level for a certain time, then the error recognition circuit 44 signals an error.This occurs by means of a positive signal at the output of the error recognition circuit 44, whereby the electromagnet 46 is excited. The consequence thereof is an unlatching of the detent 34 and the two-way valve 33 switches over to an other medium path. In the other setting of the valve 33, the pressure space of the setting mechanism 30 is relieved and the abutment 23 displaces to the left in the direction start.

Connected with the switching-over of the spring-loaded two-way valve 33 is a displacement of the abutment 25 in the direction stop into a position which corresponds to the minimum full load quantity.

By the "motion to the right" of the valve 33, also the switch 49 is opened and the current circuit of the current source 50 thereby interrupted. Thereby, the current supply to the individual electronic circuits by the voltage supply part 48 is interrupted. Nevertheless, the internal combustion engine remains controllable by the drive pedal 20.

Beyond that, a rotational speed regulation takes place through the rotational speed measuring mechanism 11. The maximum full load quantity, which is now set to a lower value by means of the abutment 25 is now changed. With proper operation of the regulating mechanism, an increased starting quantity is placed ready in the starting case, since the lever 19 in the starting case deflects the abutment 25 independently of the setting of the valve 33 so that the abutment bolt 24 does not come to bear against the abutment 25.

An automatic resetting of the two-way valve 33 is not provided in the control equipment. This resetting and thereby the notching-in of the detent 34 is left to better trained personnel who at the same time can also find out sources of error.

Fig. 2 shows details of the mechanical part of the control equipment shown in Fig. 1. The same parts are designated by the same reference symbols. The settings of the abutment in emergency operation are drawn in by solid lines. The abutment 23 due to the spring in the setting mechanism 30 has been displaced fully to the left up into a starting -quantity position. The abutment 25 stands in a position for the minimum full load quantity and is pivoted away downwardly by means of the sickle lever 19 at n = zero, i.e.

inter alia in the starting case. Drawn in dashed lines is the position of the abutment 25 in the normal operating manner of the regulator 45 and the setting mechanism 30, i.e. without an error or before an error is recognised.

With reference to Fig. 3, the starting point is the summation junction 42, in which an intended-actual-value comparison of the setting of the abutment 23 is performed. This summation junction 42 is followed by a branch leading to the abutment 25 and provided with an error recognition circuit 44 as well as the electromagnet 46 and another branch provided with the regulator 45 and the magnetic valve 35. Symbolically drawn in between the magnetic valve 35 and the setting mechanism 30 is a switch 331, which is to indicate that an error signal coming from the error recognition circuit 44 can interrupt the connection between magnetic valve 35 and setting mechanism 30. The switch 331 corresponds to the two-way valve 33. The abutment 23 follows the setting mechanism 30. A path for a repeat signal indicative of the position of the abutment 23 is shown through the transmitter 31.

Fig. 4 shows three pulse diagrams associated with the error recognition circuit 44.

The basic idea is that an error signal is delivered when either a large intended-actualvalue deviation in the position of the abutment 23 occurs over a shorter time duration or a smaller deviation of like polarity occurs over a longer time duration.

Fig. 4a shows a step response of the regulating system for an intended-value step. A rapid running-up of the actual value and an over-shooting and under-shooting, decaying in value, of the actual value relative to the intended value is recognisable. Fig. 4b shows the respective deviation.

The signal shown in Fig. 4b is integrated in the error recognition circuit 44 and the integrator is reset on each zero transition of the signal deviation. Fig. 4c shows the output value of the integrator.

When the setting regulating circuit operates free of disturbances, then the actual value of the setting mechanism follows the given intended value in accordance with the dynamic characteristics of the regulating circuit, i.e. the intended-actual-value deviation swings around the zero value during the operation. When a disturbance arises in any one regulating circuit member, then the regulating circuit is no longer closed and the amount of the difference between intended and actual value assumes a value greater or smaller than zero. The control equipment may thus be continuously monitored in respect of its functional capability in that it is tested as to whether the regulating deviation still moves around the zero point.

When the integrator value exceeds a predetermined limit, then the control equipment is switched over to emergency operation and the maximum injected quantity limited to the minimum full load quantity.

The limit is determined thereby, that its value must be greater than all integrator values which can arise with the regulating circuit functioning; i.e., for example, in the case of step-shaped, ramp-shaped or other shapes of the guide magnitude in the range up to maximum full load quantity. The limiting value is reached more rapidly, the greater the intended-actual-value deviation is. This is a desired effect, because the more the intended injection quantity is fallen below or exceeded, the more rapidly must the control equipment be switched over to emergency operation.

Fig. 5 shows a block schematic diagram of a possible realisation of the error recognition circuit 44. The circuit of Fig. 5 is provided with a zero-transition detector 60, which at its output 61 delivers a signal when the input magnitude Xw (that is the output signal of the summation junction 42) display s a zero transition. A rectifier bridge 62 ensures that a subsequent integrator 63 integrates positive and negative deviations of the intendedactual-value signal Xw in only one direction.

The integrator 63 is resettable through an input 64 by the output signal of the zerotransition detector 60. Connected to the output of the integrator 63 is a threshold value stage 65 which compares the integrator value with a permissible signal level at the input 66 of the threshold value switch 65. The output of the threshold value stage 65 is connected to an amplifier 67, which delivers the driving signal for the electromagnet 46 shown in Fig. 1.

Fig. 6 corresponds essentially to Fig. 1.

However, the drive of the abutment 23 through an electromagnetic setting mechanism 70 starting from the regulator 45 is different. When the electromagnet 46 is excited by reason of an error recognition signal from the error recognition circuit 44, then the detent 34 is released and a springloaded piston 71 in a cylinder 72 is displaced to the right together with the abutment 25.

During this movement, two switches 49 and 73 are opened, wherein the switch 49 corre sponds to the similarly designated switch shown in Fig. 1 and the switch 73 lies between the output of the regulator 45 and the electromagnet setting mechanism 70 which also contains a spring.

The control equipments shown in Fig. 1 and 6 do not differ in their effect. It is a question of expediency which mode of construction, hydraulic or electrical, is chosen and depends not least on, for example, the space conditions in the internal combustion engine among other things.

The hereinbefore described control equipments may be enlarged to a full regulator under certain presumptions. In this case, the abutment 23 is then rigidly and forcelockingly connected with the intermediate member 16. In order that in case of error, the control of the internal combustion engine is secured, the abutment 23 may then not be pushed into a fixed position, but must be separated from the setting mechanism 30 and 70 so that the regulating rod 10 can react to a change of the drive pedal setting.

Advantageously, in a control apparatus embodying the invention, signals of the individual operational characteristic magnitudes are processable into a control signal for the abutment setting mechanism and this combined signal then determines the maximum position of the regulating rod. It is thus particularly advantageous to provide a second abutment, the setting of which is independent of the position of the first abutment and which varies its original position in the direction of smaller quantity especially in the case of an erroneous driving signal for the setting mechanism of the first abutment. To secure a large starting quantity, the second abutment may be brought out of action during the starting case, in that it is, for example by means of a lever proceeding from the mechanical rotational speed counting mechanism, pivoted away from its normal engagement position.Preferably, the drive of the second abutment may take place through an error recognition circuit arrangement, in which for example regulation deviations are integrated and which provides an error signal when the integrator value exceeds a certain level.

WHAT WE CLAIM IS: 1. A control apparatus for limiting the maximum quantity of fuel to be injected in an internal combustion engine, the apparatus comprising a regulating member to determine the quantity of fuel to be injected, a regulating linkage connected with the regulating mem tiber, means responsive to the rotational speed of the internal combustion engine and coupled by means of the regulating linkage to the regulating member to control the position of the regulating member, a first abutment to limit displacement of the regulating member, the position of the first abutment relative to the regulating member being controllable in dependence upon the magnitude of operational characteristics of the internal combustion engine, and an error recognition circuit means arranged to receive a first signal indicative of the actual position of the first abutment and a second signal indicative of an intended position of the first abutment, and to provide an output signal in dependence upon the first and second signals.

2. Apparatus as claimed in claim 1, wherein the speed-responsive means is provided with fly-weights.

3. Apparatus as claimed in claim 1, comprising a second abutment to limit the quantity of fuel to be injected to that required for full load of the engine, the position of the second abutment relative to the regulating member being controllable at least in dependence upon the output signal.

4. Apparatus as claimed in claim 3, comprising respective setting means associated with the first and second abutments and each arranged to set the position of the associated abutment, the error recognition circuit means being arranged to provide the output signal to at least one of the setting means.

5. Apparatus as claimed in claim 4, wherein each of the setting means is directly controllable by the output signal.

6. Apparatus as claimed in claim 4, wherein each of the setting means is indirectly controllable by the output signal.

7. Apparatus as claimed in any one of claims 3 to 6, wherein the second abutment is so settable as to be inoperable at least during the starting operation of the engine.

8. Apparatus as claimed in claim 7, wherein the second abutment is pivotable away from the regulating member at least during the starting operation of the engine.

9. Apparatus as claimed in any one of the preceding claims, wherein the position of the first abutment is selectably settable in the presence of the output signal.

10. Apparatus as claimed in claim 9, wherein, in the presence of the output signal, the first abutment is set to a position corresponding to that associated with the quantity of fuel required during the starting operation of the engine.

11. Apparatus as claimed in any one of the preceding claims, wherein the electrically operable regulating components of the apparatus are arranged to be switched off in the presence of the output signal.

12. Apparatus as claimed in any one of the preceding claims, wherein the error

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

then the detent 34 is released and a springloaded piston 71 in a cylinder 72 is displaced to the right together with the abutment 25.

During this movement, two switches 49 and

73 are opened, wherein the switch 49 corre sponds to the similarly designated switch shown in Fig. 1 and the switch 73 lies between the output of the regulator 45 and the electromagnet setting mechanism 70 which also contains a spring.

The control equipments shown in Fig. 1 and 6 do not differ in their effect. It is a question of expediency which mode of construction, hydraulic or electrical, is chosen and depends not least on, for example, the space conditions in the internal combustion engine among other things.

The hereinbefore described control equipments may be enlarged to a full regulator under certain presumptions. In this case, the abutment 23 is then rigidly and forcelockingly connected with the intermediate member 16. In order that in case of error, the control of the internal combustion engine is secured, the abutment 23 may then not be pushed into a fixed position, but must be separated from the setting mechanism 30 and 70 so that the regulating rod 10 can react to a change of the drive pedal setting.

Advantageously, in a control apparatus embodying the invention, signals of the individual operational characteristic magnitudes are processable into a control signal for the abutment setting mechanism and this combined signal then determines the maximum position of the regulating rod. It is thus particularly advantageous to provide a second abutment, the setting of which is independent of the position of the first abutment and which varies its original position in the direction of smaller quantity especially in the case of an erroneous driving signal for the setting mechanism of the first abutment. To secure a large starting quantity, the second abutment may be brought out of action during the starting case, in that it is, for example by means of a lever proceeding from the mechanical rotational speed counting mechanism, pivoted away from its normal engagement position.Preferably, the drive of the second abutment may take place through an error recognition circuit arrangement, in which for example regulation deviations are integrated and which provides an error signal when the integrator value exceeds a certain level.

WHAT WE CLAIM IS: 1. A control apparatus for limiting the maximum quantity of fuel to be injected in an internal combustion engine, the apparatus comprising a regulating member to determine the quantity of fuel to be injected, a regulating linkage connected with the regulating mem tiber, means responsive to the rotational speed of the internal combustion engine and coupled by means of the regulating linkage to the regulating member to control the position of the regulating member, a first abutment to limit displacement of the regulating member, the position of the first abutment relative to the regulating member being controllable in dependence upon the magnitude of operational characteristics of the internal combustion engine, and an error recognition circuit means arranged to receive a first signal indicative of the actual position of the first abutment and a second signal indicative of an intended position of the first abutment, and to provide an output signal in dependence upon the first and second signals.
2. Apparatus as claimed in claim 1, wherein the speed-responsive means is provided with fly-weights.
3. Apparatus as claimed in claim 1, comprising a second abutment to limit the quantity of fuel to be injected to that required for full load of the engine, the position of the second abutment relative to the regulating member being controllable at least in dependence upon the output signal.
4. Apparatus as claimed in claim 3, comprising respective setting means associated with the first and second abutments and each arranged to set the position of the associated abutment, the error recognition circuit means being arranged to provide the output signal to at least one of the setting means.
5. Apparatus as claimed in claim 4, wherein each of the setting means is directly controllable by the output signal.
6. Apparatus as claimed in claim 4, wherein each of the setting means is indirectly controllable by the output signal.
7. Apparatus as claimed in any one of claims 3 to 6, wherein the second abutment is so settable as to be inoperable at least during the starting operation of the engine.
8. Apparatus as claimed in claim 7, wherein the second abutment is pivotable away from the regulating member at least during the starting operation of the engine.
9. Apparatus as claimed in any one of the preceding claims, wherein the position of the first abutment is selectably settable in the presence of the output signal.
10. Apparatus as claimed in claim 9, wherein, in the presence of the output signal, the first abutment is set to a position corresponding to that associated with the quantity of fuel required during the starting operation of the engine.
11. Apparatus as claimed in any one of the preceding claims, wherein the electrically operable regulating components of the apparatus are arranged to be switched off in the presence of the output signal.
12. Apparatus as claimed in any one of the preceding claims, wherein the error

recognition circuit means comprises integrator means to integrate any difference between the first signal and the second signal to thereby provide the output signal.
13. Apparatus as claimed in claim 12, wherein the integrator means is resettable on each zero transition of any difference between the first signal and the second signal.
14. Apparatus as claimed in either claim 12 or claim 13, wherein the error recognition circuit means comprises a threshold value switch, an output terminal of the integrator means being connected to an input terminal of the threshold value switch, an output terminal of the threshold value switch being for providing the output signal.
15. Apparatus as claimed in any one of the preceding claims, wherein the first abutment is connectable with the regulating member to move therewith.
16. A control apparatus substantially as hereinbefore described with reference to and as shown in Fig. 1 of the accompanying drawings.
17. A control apparatus as claimed in claim 16 and modified substantially as hereinbefore described with reference to and as shown in Fig. 6 of the accompanying drawings
18. A control apparatus as claimed in either claim 16 or claim 17 and substantially as hereinbefore described with reference to and as shown in Fig. 2 of the accompanying drawings.
19. A control apparatus as claimed in any one of claims 6 to 18 and substantially as hereinbefore described with reference to and as shown in Fig. 3 of the accompanying drawings.
20. A control apparatus as claimed in any one of claims 16 to 19 and substantially as hereinbefore described with reference to and as shown in Fig. 5 of the accompanying drawings.