JPS6020570B2 - Internal combustion engine fuel supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply device that controls the air-fuel ratio of an air-fuel mixture supplied to an internal combustion engine.

Harmful components N○× (nitrogen oxides) generated by internal combustion engines, f
In order to remove l○ (hydrocarbons) and C○ (carbon monoxide), a three-way catalyst is provided in the exhaust system to simultaneously reduce or oxidize these three harmful components.

However, the three-way catalyst only works efficiently when the air-fuel ratio of the air-fuel mixture is within a very narrow range around the stoichiometric air-fuel ratio. A fuel supply device that performs feedback control has been proposed. In other words, such a fuel supply device is provided with an integrator that integrates the output of the air-fuel ratio sensor, and if the air-fuel ratio sensor generates a rich signal in relation to the output of the integrator, it is determined that the fuel is defective. Feedback control is performed to decrease the fuel injection amount and increase the fuel injection amount when the air-fuel ratio sensor generates a lean signal. The present invention
It is an object of the present invention to improve such a fuel supply system so that when the internal combustion engine is at a warm-up temperature and a predetermined load or higher, the air-fuel mixture is diluted to reduce fuel consumption.

Preferred embodiments of the present invention will be described based on the drawings.

The intake system 1 of the internal combustion engine 9 includes an air cleaner 51 and an intake pipe 5.
2 and an intake branch pipe 11, and the other is composed of an exhaust pipe 53.

A catalytic converter 54 is provided in the exhaust pipe 53, and inside the catalytic converter 54, harmful components N○×, H in the exhaust gas are removed.
Three-way catalyst 5 that simultaneously reduces or oxidizes C and CO
5 is accommodated. 22 is a throttle valve, 56 is an intake valve, 5
7 is a cylinder, 61 is a piston, and 62 is an exhaust valve.

A flow sensor 63 is provided in the intake pipe 52 between the air cleaner 51 and the throttle valve 22 in order to measure the total flow rate of air supplied to each cylinder of the internal combustion engine 9 .

An injection valve 5 is provided in each branch passage portion of the intake branch pipe 11 that branches to each cylinder. The opening period of the injection valve 5 is controlled by the pulse width of the electric signal sent, and fuel pressurized by the injection pump 1 is supplied to each cylinder during the opening period. The input terminal of the basic air-fuel ratio setting circuit 3 is connected to the flow rate sensor 63 and the interrupter of the ignition distributor 4, and the output terminal is connected to the input terminal of the air-fuel ratio correction circuit 8. obtains information regarding the intake air flow rate from the flow rate sensor 63 and information regarding the internal combustion engine speed from the interrupter of the ignition distributor 4.The basic air-fuel ratio setting circuit 3 uses this information to adjust the air-fuel mixture to the stoichiometric air-fuel ratio. The required opening period of the injection valve 5 is calculated and sent to the pulse air-fuel ratio correction circuit 8 which has a pulse width corresponding to the opening period. It is provided in the exhaust pipe 53.

The air-fuel ratio sensor 7 detects the oxygen concentration in the exhaust gas, and when oxygen remains in the exhaust gas, that is, when the air-fuel mixture is lean, the air-fuel ratio sensor 7 detects a low level voltage (hereinafter referred to as "0"), that is, lean. On the other hand, when no oxygen remains in the exhaust gas, that is, when the air-fuel mixture is rich, a high-level voltage (hereinafter referred to as ``1''), ie, a rich signal, is generated. Air-fuel ratio sensor 7 is connected to input terminal 66 of adder 65.

Adder 65 produces an output voltage related to the sum of the voltages appearing at input terminals 66 and 67, and its output terminal 68 is connected to non-inverting terminal 72 of comparator 71. Comparator 7
The inverting terminal 73 of 1 is connected to a terminal 74 having a reference voltage value U, and the comparator 71 serves to shape the output waveform of the adder 65. Output terminal 75 of comparator 71 is connected to input terminal 77 of integrator 76 . The integrator 76 includes an operational amplifier 81 and an inverting terminal 8 of the operational amplifier 81.
2, and a capacitor 85 provided between the inverting terminal 82 and the output terminal 84 of the operational amplifier 81. A non-inverting terminal 86 of the operational amplifier 81 is grounded. Output terminal 8 of integrator T6
7, that is, the output terminal 84 of the operational amplifier 81 is an NPN
It is connected to the collector 92 of a type transistor 91.
An output terminal 84 of the operational amplifier 81 is connected to a non-inverting terminal 94 of a comparator 93. Inverting terminal 95 of comparator 93
is connected to a voltage terminal 96 having a reference voltage value W. An output terminal 97 of the comparator 93 is connected to an emitter 102 of an NPN transistor 101. The collector 103 of the transistor 101 is connected to the base 104 of the transistor 31 and the base 1 of the NPN transistor 05.
06. The collector 103 of the transistor 101 is further connected to a power supply 111 via a resistor 107. The terminal wire 12 of the transistor 105 is connected to a power source 111 through a resistor 13.The base 114 of the transistor 101 is connected to the power source 111 and the base 117 of an NPN transistor wire 16 through a resistor 115. The collector 121 of the transistor 116 is connected to the power supply 111 via the resistor 122, and the emitter 123 is connected to the input terminal 67 of the adder 65. A water temperature switch 124 and a negative pressure switch 125 are provided.The water temperature switch 24 is also attached to the water jacket in order to sense the temperature of the internal combustion engine 9.When the internal combustion engine 9 is at low temperature, The water temperature switch 1248 closes the contact, while the water temperature switch 124 opens the contact when the internal combustion engine 9 is at the temperature after the end of the engine. Intake branch pipe No. 1 downstream from 22
is attached to. When the load on the internal combustion engine 9 is less than a predetermined value, that is, when the load is low, the negative pressure switch 125 closes the contact.On the other hand, when the load on the internal combustion engine 9 is more than the predetermined value, that is, when the load is medium to high, the negative pressure switch 125 closes the contact. 125 is an open contact. The emitter 126 of the transistor 91 is connected to the collector 127 of the main transistor 105 and to the input terminal 3 of the air-fuel ratio correction circuit 8. The air-fuel ratio correction circuit 8 corrects the signal sent as a pulse width from the basic air-fuel ratio setting circuit 3 using the signal at the input terminal 131 and sends it to the injection valve 5.

The operation of this embodiment will be explained with reference to FIG. In FIG. 2, A is the voltage at the output terminal 87 of the integrator 76;
B is the voltage at the base 114 of the transistor Kame Q, C is the output voltage of the comparator 93, and D is the base 1 of the transistor 91.
04 is the voltage, and 1 is the amount of current supplied to the input terminal 131 of the air-fuel correction circuit 8. In FIG. 2, the horizontal axis is time T. 'a} When the internal combustion engine is cold or under low load, ie the period from time t to time t2.

At this time, the water temperature switch 124 and the negative pressure switch 12
5 - one is closed and B is at "0". Therefore, transistors 101 and 116 are in an open state (hereinafter referred to as "open-1"), while transistor 91 is in a closed state (hereinafter referred to as "closed"). Adder 6
Since the input terminal is not sent to the input state 67 of 5,
The adder 65 receives “1” or “0” from the air-fuel ratio sensor 7.
” is sent to the integrator 76 via the comparator 71. Since the transistor 91 is in the open state, the output voltage A of the integrator 76 is sent as is to the input terminal 131 of the air/fuel correction circuit 8. That is, during the period from time t to time The input current 1 sent to the integrator 7
It is proportional to the output voltage A of 6. Note that during the period from time t to time t2, the comparator 93 compares the output voltage A of the integrator 76 with the reference voltage W and generates an output signal of "1" or "0". Since 101 is open, this output signal has no effect on the input current 1. Thus, during this period, the air-fuel ratio correction circuit 8 adjusts the basic air-fuel ratio setting circuit according to the feedback signal from the air-fuel ratio sensor 7. Since the output signal of No. 3 is corrected and sent to the injection valve 5, the air-fuel mixture supplied to the internal combustion engine 9 is maintained at approximately the stoichiometric air-fuel ratio.
'b' When the internal combustion engine is at a temperature after the end of the engine and under medium-high load, that is, during the period from time t2 to time 4.

The water temperature switch 124 and the negative pressure switch 125 are both opened, and the voltage B at the base 114 of the transistor 101 is "
1”.

Therefore, transistor 101 and transistor ]1
6 are both "closed", the input terminal 67 of the adder 65 becomes "1", and the voltage D at the base 104 of the transistor 91 becomes equal to the output voltage C of the comparator 93. This {b)
Two more periods of b,,Q
Divide into (q) When the output voltage A of the integrator 76 is still higher than the reference voltage W, ie during the period from time t2 to time t3.

During this period, the output voltage C of the comparator 93 is still "1", so the transistor 91 is "open" and the "transistor 1g" 5 is "open". The “1” applied to the input terminal 67 is judged in the same way as the “1” sent from the air-fuel ratio sensor 7 (a signal that detects that the air-fuel mixture is mixed).
'' acts as a pseudo-rich signal on the circuit of the panbee, so the input terminal of the integrator 76 receives the signal ``IJ'' from the adder 65 via the comparator 71. Therefore, the integrator 7
The output voltage A of No. 6 decreases by a predetermined amount. This decreasing voltage is applied to the input terminal 131 of the air-fuel ratio correction circuit 8 via the transistor 91, so the opening period of the injector 5 gradually decreases and the air-fuel mixture becomes gradually leaner.
) The integrator 76 is activated when the output voltage A becomes lower than the reference voltage W, that is, during the period from time t3 to time t3.

Since the output C of the comparator 93 becomes "0", this "0" output C is sent to the transistor 91 via the transistor 101.
is transmitted to the base 104 of. Therefore, transistor 91 becomes "closed" and transistor 05 becomes "closed". In this way, the input terminal 131 of the air-fuel ratio correction circuit 8 is supplied with a predetermined current 1 from the power source 1 1 1 via the resistor 113 and the transistor 105 . In this way, the opening period of the injection valve 5 is maintained above a predetermined value, and the air-fuel ratio of the air-fuel mixture is prevented from becoming lower than necessary. {c) After the above-mentioned state {b}, when the internal combustion engine 9 becomes low temperature or under low load, that is, after the point in time.

The voltage at the base 117 of transistor 116, i.e., B
becomes "0", and both transistor 116 and transistor 101 become "open."

Therefore, the adder 65 sends only the output signal from the air-fuel ratio sensor 7 to the input terminal 77 of the integrator 76 via the comparator 71. The output voltage A of the integrator 76 starts to increase.
In this way, the amount of current supplied to the input terminal 131 of the air-fuel ratio correction circuit 8 increases from 1 to 1, and the air-fuel mixture slowly shifts to the stoichiometric air-fuel ratio, and after reaching the stoichiometric air-fuel ratio, the above-mentioned state is reached. Feedback control similar to that in case a is performed.According to the present invention, when the temperature of the internal combustion engine is above a predetermined temperature and the load is above a predetermined load, a pseudo IJ switch signal is input to the integrator to adjust the fuel injection amount. performs feedback control.

Therefore, since the fuel injection amount is reduced by the pseudo-rich signal, the air-fuel mixture is maintained lean during medium and high load periods after the end of the engine, and fuel consumption can be reduced. Furthermore, when a pseudo-rich signal occurs or disappears, the output of the integrator is gradually increased or decreased, which causes the air-fuel ratio to gradually change, which impedes the operational stability of the internal combustion engine when changing the air-fuel ratio. can be avoided. Furthermore, since the circuit for generating the pseudo-rich signal is only added to the circuit from the slave, the overall circuit configuration becomes very simple. Note that when the mixture is made lean, the efficiency of the three-way catalyst decreases, but combustion of a lean mixture suppresses the generation of C○ and HC as well as the generation of NCx, so it is useful for exhaust gas countermeasures. There is no particular problem.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing signal waveforms at each terminal of the embodiment. 5...Injection valve, 7...Air-fuel ratio sensor,
9... Internal combustion engine, 65... Adder, 7
6...Integrator, 104"""transistor, 1
16""M transistor, 124...Water temperature switch, 125...Negative pressure switch, 127...Transistor. Figure 1 Figure 2

Claims (1)

[Claims] 1 An integrator is provided to integrate the output of the air-fuel ratio sensor,
Feedback that reduces the fuel injection amount when the air-fuel ratio sensor generates a rich signal in relation to the integrator output, and increases the fuel injection amount when the air-fuel ratio sensor generates a lean signal. A fuel supply system for an internal combustion engine that performs control, wherein when the temperature of the internal combustion engine is above a predetermined temperature and the load is above a predetermined load, a pseudo-rich signal is input to an integrator to perform feedback control of the fuel injection amount. fuel supply system.