JPS6146431A - Electronic control type fuel injector - Google Patents

Abstract

PURPOSE:To prevent the overheat of a catalytic converter and improve fuel consumption by annealing-processing the detected value of an engine load and increasing fuel amount according to the result of the comparison between the load value after annealing and the set load value corresponding to the dangerous temperature of the catalytic converter. CONSTITUTION:An internal combustion engine C equipped with a catalytic converter B in an exhaust passage A is equipped with a load-signal generating means D for generating the signal corresponding to the engine load. The output signal of said generating means D is input into an annealing treatment means E, and annealing treatment is carried-out for the detected load value in order to obtain the load value approximate to the variation through time of the temperature rise of the catalytic converter B, accompanied by the increase of the engine load from the detected load value. The load value after annealing treatment by the annealing processing means E and the value which is a predetermined set- load value and corresponds to the allowable temperature of the catalytic converter B are compared in a comparing means F, and when the load value after annealing is over a set value, a fuel-amount increasing means G is operated to increase fuel amount.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an electronically controlled fuel injection device for an internal combustion engine (hereinafter also referred to as an engine), which prevents overheating of a catalytic converter for exhaust emissions and at the same time reduces fuel consumption. The present invention relates to an electronically controlled fuel injection device that can achieve improvements.

[Prior Art 1] Conventionally, an electronically controlled fuel injection device having a function of preventing overheating of a catalytic converter for exhaust emission countermeasures of an internal combustion engine installed in an automobile has been disclosed, for example, in Japanese Patent Application Laid-Open No. 1986- Examples include those shown in Japanese Patent No. 81235.

In addition, as an electronically controlled fuel @body system that adopts another example of the above-mentioned overheat prevention measures, there is a risk that the catalytic converter 7 will exceed the permissible temperature as the engine exhaust temperature increases within the actual use range of the automobile. The temperature range is confirmed in advance through experiments, and if the engine load for estimating the catalytic converter temperature, such as the engine intake air amount or engine throttle opening, exceeds the set value indicating the above-mentioned dangerous temperature range,
An electronically controlled fuel injection device that immediately activates the fuel increase mechanism is conceivable.

The reason for increasing the amount of fuel in this way will be explained with reference to FIG.

As shown in FIG. 6, - the internal temperature T('
C) reaches the saturation temperature at a higher temperature as the intake air amount Q increases, which is approximately proportional to the intake air ff1Q (rI?/hr) during steady operation under a constant air-fuel ratio (A/F). This is because the engine exhaust gas temperature is higher under operating conditions where the intake air IQ is higher. When the A/F is near the stoichiometric air-fuel ratio of 14.6, the exhaust gas temperature increases as the A/F shifts toward the lean side, and conversely, the exhaust gas temperature decreases as the A/F shifts toward the rich side. In addition, the gas reaction inside the catalytic converter is active as far as 7m near A/F 14.6.
When deviates from around 14.6, both the lean and rich sides decrease, and the amount of heat generated by the reaction decreases. Therefore, since enriching the A/F has two effects: lowering the exhaust gas temperature and lowering the exothermic reaction of the catalytic converter itself, the fuel increase mechanism as described above is operated to prevent the catalytic converter from overheating.

[Problems to be solved by the invention] However, depending on how the engine load changes during actual use of a car, the heat capacity of the catalytic converter may cause the catalytic converter to change even when the engine load exceeds the above set value. The temperature may not be within the dangerous range.

According to an electronically controlled fuel injection device that operates the fuel increase mechanism as described above immediately when the engine load exceeds a set value, there is a problem that fuel efficiency deteriorates because the fuel increase is performed even in the above cases. be.

The present invention aims to solve the above problems. That is, an object of the present invention is to make it possible to more accurately estimate the temperature of the catalytic converter, thereby preventing the undesired increase in fuel amount as described above, thereby preventing overheating of the catalytic converter, and at the same time improving fuel efficiency. An object of the present invention is to provide an electronically controlled fuel injection device that can achieve the following objectives.

[Means for Solving the Problems] Therefore, as shown in FIG. a load signal generating means that generates a corresponding signal; and from a detected load value based on the signal from the load signal generating means, the catalytic converter B increases as the engine load increases.
In order to obtain a load value that approximates the temporal change in temperature rise,
A smoothing processing means E performs smoothing processing on the detected load value, and a load value after smoothing by the cough smoothing processing means E and a predetermined set load value corresponding to the allowable temperature of the catalytic converter B. The present invention is characterized by comprising a comparison means F for comparing the magnitudes of the values, and a fuel increase means G that is executed when the load value after the rounding is equal to or higher than the set value by the comparison means F. Note that the other reference numeral 1'' in FIG. 1 represents an intake passage, and the symbol ■ represents an injector.

[Example] The present invention will be described in detail with reference to the drawings.

FIG. 2 is a system diagram of an electronically controlled fuel injection engine to which the present invention is applied. The air sucked through the air cleaner 1 is connected to an air 70 meter 2 (corresponding to the load signal generating means according to the present invention), a throttle valve 3, a surge tank 4, and an intake boat 5.
, and is sent to the combustion chamber 8 of the engine body 7 via an intake passage 12 that includes the intake valve 6 . The throttle valve 3 is linked to an accelerator pedal 13 on the driver's seat. The combustion chambers are divided by the cylinder head 9, the cylinder block 10S, and the piston 11, and the exhaust gas generated by combustion of the air-fuel mixture passes through the exhaust valve 15, the exhaust port 16, the exhaust manifold 17, and part of the exhaust passage. An exhaust pipe 18 which is a catalytic converter 18
a and then released into the atmosphere. The bypass passage 21 connects the upstream of the throttle valve 3 and the surge tank 4, and the bypass flow control valve 22 controls the area of the bypass passage FB 21 to maintain a constant interlayer rotational speed during idle linking. An exhaust gas recirculation (EGR) passage 23 that directs exhaust gas to the intake air volume to suppress the generation of nitrogen oxides connects the exhaust manifold 17 and the surge tank 4;
On-off valve type exhaust gas recirculation (EGR) control valve 24
opens and closes the EGR passage 23 in response to electric pulses. An intake temperature sensor 28 is provided in the air flow meter 2 to detect the intake temperature, and a throttle position sensor 29 detects the opening degree of the throttle valve 3. The water temperature sensor 30 is located in the cylinder block 1
A well-known air-fuel ratio sensor 31 as an oxygen concentration sensor is attached to the collecting part of the exhaust manifold 17 to detect the oxygen concentration in the collecting part, and a crank angle sensor 32 detects the crank angle of the crankshaft from the rotation of the shaft 34 of the power distributor 33 coupled to the crankshaft (not shown) of the engine body 7, and the vehicle speed sensor 35 detects the rotational speed of the output shaft of the automatic transmission 1J36. do. These sensors 2.28.29.30.31
．． The output of 32.35 and the voltage of the storage battery 37 are sent to the electronic control unit 40. A fuel injection valve 41 is provided near each intake port 5 corresponding to each cylinder, and a fuel injection valve 41 is provided near each intake port 5, corresponding to each cylinder.
2 is sent from the fuel tank 43 to the fuel injection valve 41 via the fuel passage 44. The electronic control unit 40 calculates the fuel injection amount using input signals from each sensor as parameters, and sends an electric pulse having a pulse width corresponding to the calculated fuel injection amount to the fuel injection valve 41. The electronic control unit 40 also controls the bypass flow control valve 22, the EGR control valve 24, the solenoid valve 45 (FIG. 3) of the hydraulic control circuit of the automatic transmission, and the ignition coil 4.
Control 6. The secondary side of the ignition coil 46 is connected to the power distributor 35. The charcoal canister 48 accommodates activated carbon 49 as an adsorbent, has an inlet port connected to the upper space of the fuel tank 43 via a passage 50, and an outlet side port connected to a purge port 52 via a passage 51. has been done. The purge boat 52 is located upstream of the throttle valve 3 when the throttle valve 3 is at an opening smaller than a predetermined opening, and on the other hand, the purge boat 52 is located upstream of the throttle valve 3 when the throttle valve 3 is at a predetermined opening or more.
It is located further downstream and receives negative pressure in the intake pipe. The on-off valve 53 has a bimetal disc, and closes the passage 49 to stop releasing fuel evaporative gas into the intake system when the engine is at a low temperature lower than a predetermined temperature.

FIG. 3 shows details of the electronic control section 40.

CPLJ (Central Processing Unit) 56 consisting of a microprocessor, ROM (Read Only Memory) 57, and RAM
(Random access memory) 58, another RAM 59 as a non-volatile memory element that can be supplied with power from the auxiliary power supply and retain memory even when the engine is stopped, A/D with multiplexer
The (analog/digital) converter 60 and the buffered l10 (input/output) device 61 are connected to each other via a bus 62. Air flow meter 2, intake temperature sensor 2
8. Water temperature sensor 30. The outputs of the air-fuel ratio sensor 31 and the storage battery 37 are sent to the A/D converter 60.

Further, the outputs of the throttle position sensor 29 and crank angle sensor 32 are sent to the r10561, and the bypass flow control valve 22, EGR control valve 24, fuel injection valve 41, solenoid valve 45, and ignition coil 46 are sent to the I10 device 61.
It receives input from the CPU 56 via.

The electronic control unit 40 executes a catalytic converter overheat prevention fuel increase process as shown in the flowchart of FIG. 4 as a process according to the present invention in accordance with a control program stored in the ROM 57 in advance. The details of this process will be explained below.

First, in step 101, the intake air ff1Q (rrf/hr) based on the signal from the air flow meter 2, that is, the detected load value is read into the CPU 56.

Next, in step 102, the read intake air 11Q is smoothed, and the smoothed intake air ff1Q,l, that is, the smoothed load value is given as 1. This processing content corresponds to the sluggish processing means of the present invention. Here, the smoothing process is as shown in the diagram, the intake air ff1
Q takes a constant value Qo until time to, and from time 9 to Naotoshi until just before time t1, it draws an increasing curve as shown in the figure, and after time t1, the catalytic converter 18a reaches the dangerous temperature TL.
When the intake air ff1Q changes to take a constant value QL when 18a
This is performed for the intake air mQ so as to obtain a change curve for the intake air ff1QT similar to the change curve under the temperature of .

In this smoothing process, the intake air mQ@Q when the catalytic converter overheating prevention fuel increase routine is executed this time is
l, intake air ff after being annealed during the previous execution
Letting 1QT be Q, L-, the intake air ff1Q after the annealing process during this execution is ΔQpak-Qdingt-++
It is calculated from the formula (Qi-Q+-+)/n.

Next, in step 103, a comparison is made between the 10 annealed intake air obtained in step 102 and a predetermined set value A. This comparison process corresponds to the comparison means according to the present invention. Here, the set value A is the catalytic converter 18a.
This is the value of the intake air JuQ corresponding to the critical temperature T, , that is, IIIQL in FIG.

If the smoothed intake air IQT is larger than the set value A, then in step 104, an increase value FOTP is calculated. Since this increase value FOTP differs depending on the intake air ff1Q, it is obtained by indexing a map or table in the ROM 57, which stores the minimum necessary values determined in advance through experiments, and then performing interpolation calculations. Next, in step 105, this increase value FOTP is taken into the fuel vl increase register.

Then, in step 106, the increase value FOTP is added to the normal injection amount determined in another routine, and the injector 41 is driven based on the obtained injection amount.

On the other hand, if it is determined in step 103 that the intake air amount QT after smoothing is less than the set value A, step 104 and step 105 are not executed and step 106 is directly performed.
The process moves to , and the fuel N@ injection is performed using normal rQ injection without the increase correction.

Note that the processing from step 104 to step 106 above corresponds to the fuel increase means according to the present invention.

As is clear from the above explanation, when the intake air ff1Q changes as shown in FIG. The fuel increase starts from the time t1 when the intake air mQ reaches the setting 1i11Q, which results in over-richness, but according to this embodiment, the smoothed intake air ff1Q reaches the setting II.
When IIQL is reached, the fuel increase starts at 2, and therefore, there is no need to undesirably increase the fuel amount for the time (t2-j+), which prevents overheating of the catalytic converter and improves fuel efficiency. becomes achievable.

[Effects of the Invention J As explained above, the present invention provides a method for adjusting the detected load value to obtain a load value that approximates the temporal change in the temperature rise of the catalytic converter due to an increase in engine load. The load value after the annealing is compared in magnitude with the set load value corresponding to the critical temperature of the catalytic converter, and when the load value after the annealing exceeds the set load value, Increased fuel amount only. Compared to the idea based on the premise of the present invention, in which fuel increase is started even though the internal temperature of the LC catalytic converter is sufficiently lower than the dangerous temperature, the time to start fuel increase can be delayed. Fuel efficiency can be improved.

In the above embodiment, the air flow meter 2 is used as the load signal generating means, but the throttle position sensor 2 is also used as the load signal generating means.
9 may be substituted, and in this case as well, the same effect as in the above-mentioned embodiment can be obtained.

[Brief explanation of the drawing]

FIG. 1 serves only to clarify the invention. Figures 2 to 5 show an embodiment of the present invention, where Figure 2 is an overall configuration diagram, Figure 3 is an internal configuration diagram of an electronic control unit, and Figure 4 shows processing by the electronic control unit. The flowchart in FIG. 5 is an explanatory diagram for explaining this process. M
Figure 6 is the premise of the present invention.Figure 3, Figure 4, Figure 5, front.

Claims (1)

[Scope of Claims] An internal combustion engine equipped with a catalytic converter in an exhaust passage, comprising: load signal generating means for generating a signal corresponding to engine load; and a detected load value based on the signal from the load signal generating means, smoothing processing means for performing smoothing processing on the detected load value in order to obtain a load value that approximates a temporal change in temperature rise of the catalytic converter accompanying an increase in load; a comparison means for comparing the load value after the smoothing with a predetermined set load value corresponding to the permissible temperature of the catalytic converter; An electronically controlled fuel injection device comprising: fuel increasing means that is executed at a certain time.