JPS5934431A - Internal-combustion engine of fuel injection type - Google Patents

Abstract

PURPOSE:To obtain accurate measurements of the suction air temperature by furnishing both a suction pipe pressure sensor and a suction air temp. sensor in the understream of the suction air heating part and by installing these sensors at the divergent point of the intake manifold. CONSTITUTION:The fundamental amount of fuel injection is determined in accordance with the engine's number of revolutions obtained by a crank angle sensor 40 and the suction pipe's pressure obtained by a suction pipe pressure sensor 22, the latter being corrected on the basis of suction air temp. given by a suction air temp. sensor 23, and this determined fundamental amount undergoes a correction on the basis of air-fuel ratio informed from an oxygen density sensor 30 and the engine cooling water temp. informed from a cooling water temp. sensor 42 to determine the rate of fuel injection, and a signal for valve opening is sent to the injector 18, and at the time of heavy load a digital control circuit 50 outputs a switching signal for by-pass valve 24 to a negative pressure change-over valve 48. These sensors 22, 23 are both installed at the divergent point of the suction manifold 20 to allow acquisition of high-precision suction pipe pressure signal and suction air temp. signal. Thus air-fuel ratio can be performed highly accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection type internal combustion engine, and in particular to an intake pipe suitable for use in an automobile engine equipped with a single point injection type electronically controlled fuel injection device and an intake air heating device. It has a single injector located upstream of the throttle valve, and an intake air heating section located downstream of the intake pipe, and is capable of controlling engine operating conditions such as engine speed, intake pipe pressure, and intake temperature. controlling the fuel injection amount by the injector according to the
This invention relates to an improvement in a fuel-injected internal combustion engine that heats an air-fuel mixture.

One method of controlling the air-fuel ratio of an air-fuel mixture in an internal combustion engine such as an automobile engine is to use an electronically controlled fuel injection device. Such an electronically controlled fuel injection device, for example, 1
In an internal combustion engine equipped with a point injection type electronically controlled fuel injection device, the fuel injection amount is determined according to, for example, the engine rotation speed, intake pipe pressure, intake temperature, etc. The air-fuel ratio of the engine is controlled by opening a single injector that injects fuel into the engine's intake passage, which is located upstream of the throttle valve in the intake pipe. It has come to be used in automobile engines equipped with exhaust gas purification measures that require precise control of the fuel ratio.

On the other hand, it is necessary to improve the output performance of the engine by increasing the fuel vaporization performance and the distribution performance of the air-fuel mixture to each cylinder (for example, an intake heating section that uses high-temperature exhaust gas as a heat source is installed downstream of the intake pipe). Attempts to heat the air-fuel mixture using the intake air heating section have also failed.

It is conceivable to use such heating of the air-fuel mixture by the intake air heating section in combination with the above-mentioned one-point injection type electronically controlled fuel injection device, but in that case, when determining the fuel injection amount by the injector, The problem was the location of the intake pipe pressure sensor for detecting the intake pipe pressure and the intake air temperature sensor for detecting the intake air temperature, both of which are required for this purpose. That is, the intake air temperature sensor may be installed in the air cleaner section, as in the case of a multi-point injection type electronically controlled fuel injection system, or it may be installed directly above the intake air heating section (
・In the former case, the intake pipe pressure measurement location detected by the intake pipe pressure sensor, which must be installed downstream of the throttle valve, and the intake flow measurement location may be far apart. Therefore, it becomes difficult to accurately detect the intake pipe pressure and the intake air temperature, which are closely related to each other due to relationships such as pressure transmission. In the latter case, although it is possible to place the intake air temperature sensor near the intake pipe pressure sensor, the intake air temperature detected by the intake air temperature sensor is the value before the temperature has completely risen. , On the other hand, the intake pipe pressure detected by the intake pipe pressure sensor, especially in the case of a multi-cylinder engine,
It is not the pressure at a specific point (it is the average pressure, so it is still sometimes difficult to accurately detect the intake pipe pressure and intake temperature. Therefore, in both cases, for example, when the internal combustion engine There are few problems when the vehicle equipped with the vehicle is stationary, but when the vehicle is running and the intake manifold is exposed to the air-fuel ratio, the air-fuel ratio may change due to the strength of the wind. There were cases where the value deviated from the target value.Such problems are especially common in internal combustion engines.
This is a so-called partial control system that cancels feedback control according to the oxygen concentration sensor output depending on the engine operating conditions, and performs feedforward control of the fuel injection amount by the injector depending on the engine operating conditions such as engine speed and intake pipe pressure. This becomes a big problem in operating conditions where an error in measuring the intake air temperature directly becomes an error in the control of the air-fuel ratio, such as in combustion control.

The present invention has been made to solve the above-mentioned conventional drawbacks, and regardless of changes in engine operating conditions such as vehicle running conditions,
An object of the present invention is to provide a fuel injection internal combustion engine that can perform accurate air-fuel ratio control. and an intake air heating section disposed on the downstream side of the injector, which controls the amount of fuel injected by the injector according to engine operating conditions such as engine speed, intake pipe pressure, and intake temperature, and heats the air-fuel mixture. In the fuel injection internal combustion engine configured as above, an intake pipe pressure sensor for detecting intake pipe pressure and an intake temperature sensor for detecting intake air temperature are both disposed downstream of the intake air heating section. In this way, the above objective was achieved.

Further, the intake pipe pressure sensor and the intake temperature sensor are arranged at a branch part of the intake manifold, so that more accurate measured values can be obtained.

Embodiments of the fuel injection internal combustion engine according to the present invention will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 2, this embodiment includes an air cleaner 12 for taking in atmospheric air, and an intake pipe 14 arranged upstream of a throttle valve 16 through which the intake air taken in by the air cleaner 12 flows. a single injector 18 that injects fuel toward the throttle valve 16, which is installed at an intake pipe pressure sensor 22 and an intake air temperature sensor 23 disposed downstream from the intake air heating section 21 at the second branch of the intake manifold 20; and an intake pipe pressure sensor 22 and an intake air temperature sensor 23 disposed near the intake boat of the engine 10. The engine combustion chamber 10a is connected to the engine combustion chamber 10a through the bypass valve 24 and the intake valve 25, which generate or eliminate swirl in the air-fuel mixture taken into the engine combustion chamber through the intake boat, depending on the engine operating conditions. a spark plug 26 for igniting the air-fuel mixture introduced into the spark plug 26;
An exhaust manifold 28 for collecting exhaust gas, and an oxygen concentration sensor 3 disposed at the collection part of the exhaust manifold 28 for detecting the air-fuel ratio from the residual oxygen concentration in the exhaust gas.
0, a catalyst conduit 32 disposed on the downstream side of the exhaust manifold 28, an exhaust pipe 34, and a distributor having a distributor shaft (not shown) that rotates in conjunction with the rotation of the crankshaft of the engine 10. 36 and
A top dead center sensor 38 and a crank angle sensor 40, which are built in the distributor 36 and output a top dead center signal and a crank angle signal, respectively, according to the rotation of the distributor shaft, and an engine mounted in the engine block. A cooling water sensor 42 for detecting wetness of cooling water, a diaphragm device 44 for opening and closing the bypass valve 24, and a diaphragm chamber 44a of the diaphragm device 44. , throttle valve 16
Air or gas filter 45 and check valve 4 on the more upstream side
Intake pipe pressure (negative pressure) 'f taken out from the intake manifold 20 via 6: engine rotational speed determined from the negative pressure switching valve 48 for introduction and the crank angle signal output from the crank angle sensor 40; and the intake temperature sensor 2
The basic fuel injection amount is determined according to the intake pipe pressure output from the intake pipe pressure sensor 22, which has been accurately corrected by the intake air temperature output from the three outputs, and is determined based on the air-fuel ratio output from the oxygen concentration sensor 30 and the cooling water temperature sensor 42. By correcting the output in accordance with engine cooling water wetness, etc., the fuel injection amount is determined, and a valve opening signal is output to the injector 18, and the bypass valve 24 is opened at high load depending on the engine operating state.
The digital control circuit 50 outputs a bypass valve switching signal to the negative pressure switching valve 48, and the bypass valve 24 is closed to generate swirl during medium and low loads. The digital control circuit 50, as shown in detail in FIG. a power supply circuit 58 for supplying the power supply voltage supplied from the battery 56 to the CPU 52; a timer 60; and a rotation speed counter 62 for calculating the engine rotation speed by counting the output of the crank angle sensor 40. , according to the output of the rotation number counter 62,
Interrupt control for interrupting the CPU 52? 1
164, the intake pipe pressure signal output from the intake pipe pressure sensor 22, the intake temperature signal output from the intake temperature sensor 23, the air-fuel ratio signal output from the oxygen concentration sensor 30, and the cooling water temperature signal output from the cooling water temperature sensor 42, in sequence. An analog input port 6 for importing, and a random access memory (for temporarily storing calculation data etc. in the CPU 52)
A read-only memory (referred to as ROM) 70 for storing programs or various constants, etc., and a counter that counts the number of valve opening times of the injector 18 according to the calculation results in the CPU 52. 72, a power amplifying section 74 for power amplifying the output of the counter 72 and outputting it to the injector 18, and outputting a bypass valve switching signal to the negative pressure switching valve 48 according to the calculation result in the CPU 52. It consists of an output port door 6.

The action will be explained below.

The calculation of the fuel injection amount in this embodiment is performed according to a fuel injection amount calculation routine as shown in FIG.

That is, first in step 101, the cooling water wetness sensor 42
Depending on the output, etc., each state value for determining whether lean combustion is executable is read. Next, the process proceeds to step 102, where each lean determination condition is compared to determine whether all lean determination conditions are satisfied. If the determination result is positive, the process proceeds to step 103, where the air-fuel ratio lean correction coefficient FLKAN (
<1); and the air-fuel ratio feed/(if the ivy correction coefficient F'ya is set to 1, for example, the desired fuel-fuel ratio is 22 to 2
Make sure that about 3 degrees of glue combustion takes place. On the other hand, if the determination result in step 102 is negative, the process proceeds to step 104, where the air-fuel ratio lean correction coefficient is determined.

Set FLEAN@1 to perform air-fuel ratio feedback control. Step 103 or 1.04
After the completion, the process proceeds to step 105, where the intake air temperature sensor 23
Depending on the output, etc., state values for calculating the fuel injection amount are entered.

Next, the process proceeds to snap 106, where the fuel injection amount 'r is completely calculated and set using, for example, the following formula.

T = TBAsg XFFB XF X'FTA XF
LEAN--(1) Here, TBASE is a basic injection lid and is determined by the engine speed and intake pipe pressure. Further, F is an increase coefficient, which is used to increase the acceleration amount at the time of acceleration, for example, depending on the engine operating state.

Furthermore, PTA is an intake air temperature correction coefficient.

In this embodiment, both the intake pipe pressure sensor 22 and the intake temperature sensor 23 are placed at the branch part of the intake manifold 20, so that highly accurate intake pipe pressure signals and intake temperature signals can be obtained. Can be done.

Similarly, the installation positions of the intake pipe pressure sensor and the intake air temperature sensor are not limited to these, and may be located at other locations as long as they are downstream from the intake air heating section 21.

Further, in this embodiment, the present invention is applied to the bypass valve 24.
Since it is used in conjunction with partial lean control using VC, accurate air-fuel ratio control can be performed, especially during lean combustion which requires accurate intake temperature correction, and engine operating performance can be maintained. Similarly, the method of applying the present invention is not limited to this, and it is of course possible to use it separately from lean combustion.

As explained below, according to the present invention, it is possible to perform highly accurate air-fuel ratio control regardless of changes in engine operating conditions such as vehicle running conditions, thereby improving engine startability, acceleration, etc. Ditto for overall driving performance can be measured. Further, it has excellent effects such as easy installation of each sensor and good serviceability.

When the intake temperature sensor 23 is installed in the air cleaner section 12 (broken line A), when it is installed directly above the intake air heating section 21 (
An example of the relationship between the state of change in the detected intake air temperature and the state of change in the air-fuel ratio during lean combustion when installed on the downstream side of the intake air heating unit 21 according to the present invention (solid line C) and the dashed line B). It is shown in FIG. In FIG. 5, when the time t1-t is 20°C, the time t1-t is 20°C.
If t8 raises the intake air temperature of the air cleaner section to 40°C, then time t3 to 1. However, the intake temperature in the air cleaner section is set to 2 again.
This is a case where the temperature is returned to 0°C, and both times t and t4 are cases where the airflow does not hit the intake manifold section. On the other hand, after time t, the vehicle starts running and the intake manifold section is exposed to the running wind. When installed in the air cleaner section and when installed directly above the intake air heating section, there is almost no deviation in the air-fuel ratio when there is no running wind, but after time t4, running wind hits the intake manifold. If it is installed on the air cleaner section with a 1"L" air-fuel ratio, the air-fuel ratio will deviate by about 4% from the base air-fuel ratio of 22, and even if it is installed directly above the intake air heating section, the air-fuel ratio will deviate by about 2%. It is clear that there are. On the other hand, in the case of the present invention, the air-fuel ratio hardly deviates.

[Brief explanation of the drawing]

FIG. 1 is a sectional view including a partial block diagram showing the overall configuration of an embodiment of a fuel injection internal combustion engine according to the present invention;
83 is a schematic plan view showing the mounting positions of the intake pipe pressure sensor and intake air temperature sensor in the embodiment, FIG. 83 is a block diagram showing the configuration of the digital control circuit used in the embodiment, and FIG. Figure 5 is a flowchart showing the same (fuel injection amount calculation routine), and Figure 5 is a diagram showing an example of the relationship between the presence or absence of running wind, the intake temperature sensor output, and the air-fuel ratio during lean combustion in the above embodiment and comparative example. 10...Engine, 14...Suction fi'f, 16...
・Throttle valve, 18... Injector, 20...
Intake manifold, 21... Intake heating section, 22... Intake pipe pressure sensor, 23... Intake temperature sensor, 36...
Distributor, 40...Crank angle sensor, 5
0...Digital control circuit. Agent Takaya Ron (and 1 other person)

Claims (2)

[Claims] (1) A fuel injection system disposed upstream of the throttle valve of the intake pipe, which controls the amount of fuel injected by the injector according to engine operating conditions such as pipe pressure and intake temperature, and heats the air-fuel mixture. In the internal combustion engine, an intake pipe pressure sensor for detecting intake pipe pressure and an intake temperature sensor for detecting intake air temperature are both arranged downstream of the intake air heating section. A fuel-injected internal combustion engine. (2) The fuel injection internal combustion engine according to claim 1, wherein the intake pipe pressure sensor and the intake temperature sensor are arranged at a branch part of an intake manifold.