JP2656491B2 - Engine control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device that improves control accuracy and reliability of an internal combustion engine in which exhaust gas recirculation is performed.

[Conventional technology]

Generally, control of an internal combustion engine such as an automobile has different control characteristics depending on the operating state of the engine. That is, the control amount using the engine speed N and the load data (for example, intake load) L as parameters, such as the air-fuel ratio and the ignition timing, are different.

Therefore, in order to operate the engine efficiently, it is necessary to control the ignition timing and the like with high accuracy in accordance with the operation state of the engine. N, control amount data (ignition advance value, etc.) corresponding to load data L
A method of storing the information in a ROM (read-on memory) is conceivable.

For example, as described in Japanese Patent Application Laid-Open No. 48-68931, data relating to ignition timing is stored in the ROM as a two-dimensional table memory using the above-mentioned rotation speed N and load data L as two-dimensional coordinate points. In some cases, the ignition timing of the engine is controlled based on data obtained from the table sequentially according to the operating state of the engine.

By the way, when an exhaust gas recirculation device is added to the internal combustion engine controlled as described above, the operating state of the engine changes according to the amount of exhaust gas recirculation.
It is necessary to determine the control amount such as the ignition timing by adding data on the exhaust gas recirculation amount to the load data L.

In this case, the data relating to the exhaust gas recirculation amount may use a valve lift amount of a control valve for controlling the amount of exhaust gas recirculation (hereinafter referred to as EGR), or a negative pressure type as a means for driving the control valve. When using an actuator,
Signals such as a load value to be sent to the driving means and a driving current for an electric actuator are used.

The control amount data such as the ignition timing is stored in a memory such as a ROM in addition to the rotation speed data N, the load data L, and the EGR data E as described above as parameters. That is, the rotational speed N, the load L, and the EG
Data stored in a corresponding location in the memory is sequentially read in accordance with the data E of R, and a control amount such as an ignition timing is determined based on the read data.

[Problems to be solved by the invention]

The detected values of the rotation speed N and the load data L (for example, the intake negative pressure) hardly change with time within the service life of the engine. Due to the long-term use, carbon and the like contained in the exhaust gas adhere in large quantities to the EGR control valve and its passages, and the value at the time of initial use and a considerable change with time after long-term use.

Therefore, since the detected value does not correspond to the actual operating state of the engine, the control amount of the engine deviates from the value at the time of the initial stage, and there is a problem that high-precision engine control cannot be performed.

The present invention has been made to solve such problems, and has little control over time and high control accuracy and reliability even when used for a long time, and also improves exhaust gas purification performance and fuel consumption performance. It is intended to obtain an engine control device.

[Means for solving the problem]

An engine control device according to the present invention includes: data for determining a control parameter of an internal combustion engine corresponding to a plurality of operating states of the internal combustion engine that are divided by an operation parameter and a calculation amount calculated from an oxygen concentration in intake air. It has a storage means for storing, and a means for outputting an operation signal of a control parameter based on storage data corresponding to an operation parameter and a calculation amount calculated from the oxygen concentration.

(Operation)

According to the present invention, a plurality of operating states of the internal combustion engine are determined by an operation amount calculated from an oxygen concentration in the intake air after a part of the exhaust gas of the internal combustion engine is recirculated to the intake system and an operating parameter representing the operating state of the internal combustion engine. The control parameters of the internal combustion engine are determined in accordance with the divided operating states and stored in the storage means, and the operation parameters and the operation amount calculated from the oxygen concentration after the exhaust gas is recirculated into the intake air are calculated. An operation signal of a control parameter of the internal combustion engine is output according to the corresponding stored data.

〔Example〕

Hereinafter, embodiments of the engine control device of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of one embodiment.

In FIG. 1, reference numeral 1 denotes an engine main body, and an intake duct 6 is connected to the engine main body 1 via an intake manifold 2, and an air cleaner 7 is disposed at a tip end of the intake duct 6. ing. The throttle valve 5 is arranged at a predetermined position of the intake duct 6.

In the intake manifold 2, the engine body 1
A fuel supply device 4 is attached to a connecting portion of the engine main body 1. An exhaust manifold 3 is connected to the engine body 1, and a spark plug 18 is attached to the engine body 1.

The exhaust manifold 3 and the intake manifold 2 are EGR
The exhaust gas recirculation control valve 12 (hereinafter, referred to as an EGR valve) is provided in the middle of the EGR passage 11. The EGR valve 12 controls the amount of exhaust gas recirculation. In this embodiment, a valve that is driven by a pressure diaphragm using negative intake pressure as a driving source is used.

This intake negative pressure is supplied to the intake duct 6 through the negative pressure introduction passage 9.
The pressure in the intake manifold 2 is detected by an intake negative pressure detector 10 through the negative pressure introduction passage 9.

Further, the reciprocating motion of the piston 1a of the engine body 1 is converted into a rotational motion by a crank mechanism, and the rotation of the crank mechanism, that is, the engine speed is detected by the engine speed detector 8. It has become. The crank angle position of the engine is detected by the crank angle sensor 20.

The output of the engine speed detector 8, that is, the engine speed signal N is output to the EGR control circuit 14 and the computer 22, and the output of the crank angle sensor 20,
That is, the crank angle signal CA is output to the computer 22.

The aforementioned intake manifold 2, the oxygen sensor 21 is provided, the detection output of the oxygen sensor 21, i.e. the oxygen concentration signal O ₂ is also adapted to deliver computer 22.

The oxygen sensor 21 has a sensor portion disposed downstream of the opening of the intake manifold 2 to the EGR passage 11 (on the side of the engine body 1), and is proposed in, for example, Japanese Patent Application Laid-Open No. 58-153155. Like a solid electrolyte oxygen pump type oxygen sensor, it generates a current output (mA) proportional to the oxygen concentration.

Further, the intake negative pressure detector 10 detects detects the pressure in the intake manifold 2 output, i.e., the intake pressure signal P _B is adapted to deliver to the computer 22 and the EGR control circuit 14. The EGR control circuit 14 adjusts the EGR valve 12 so as to change the EGR amount to a set value according to the intake negative pressure and the engine speed.

The computer 22 is mainly composed of a microcomputer, and the main input signals to this computer are, as described above, an engine speed signal N and a crank angle signal.
CA, oxygen concentration signal O ₂ in intake gas, throttle valve 5
And the like downstream of the intake pressure signal P _B.

The output signal from the computer 22 is the spark plug drive
An electric signal corresponding to the energizing time of the ignition coil is output, specifically, an electric signal to 19.

The spark plug driving device 19 is for generating an electric spark in the spark plug 18, and includes a known ignition coil, a power transistor for interrupting the coil current, and the like.

The ignition coil 18 supplies an ignition spark to an air-fuel mixture in a cylinder of the engine body 1.

Next, a detailed configuration of the EGR control circuit 14 will be described with reference to FIG. In FIG. 2, A / D (analog /
The digital) converter 101, being adapted to the intake pressure signal P _B from the intake negative pressure detector 10 are input, f / D
The (frequency / digital) converter 102 receives an engine speed signal N from the engine speed detector 8.

The outputs of the A / D converter 101 and the f / D converter 102 are sent to a digital operation circuit 103, respectively. The digital arithmetic circuit 103 converts these outputs into digital signals and outputs read signals [P _B ] and [N] of the storage circuit 104 to the storage circuit 104.

The output of the storage circuit 104 is sent to a pulse calculation circuit 105, and the pulse calculation output circuit 105 outputs the output to the EGR control valve 12.

The internal configuration of the computer 22 is shown in FIG. In the Figure 5, A / the D converter 201 are adapted to the intake pressure signal P _B is input, the engine speed signal from the engine speed detector 8 to f / D converter 202 N
Is entered.

The A / D converter 201 and f / D converter 202 convert each input signal to a digital signal and
203. The digital operation circuit 203 outputs read signals [P _B ] and [N] from the outputs of the A / D converter 201 and the f / D converter 202 to the storage circuit 204.

On the other hand, the arithmetic conversion circuit 210, adapted to deliver the digital arithmetic circuit 213 to calculate the EGR ratio K by entering the sensor output I _P of the oxygen sensor 21. The arithmetic conversion circuit 210 is configured by a digital circuit or an analog circuit.

The digital arithmetic circuit 213 receives the EGR rate K and stores
A read signal [E] is output to 204.

The contents stored in the storage circuit 204 will be described later in the section of operation description. The output of the storage circuit 204 is sent to the pulse operation circuit 205. The pulse arithmetic circuit 205 includes:
An energization pulse signal for the ignition coil is output to the ignition drive device 19 using the output CA of the crank angle sensor 20 as a reference angle signal.

Next, the operation of the present invention will be described. First, EGR
Will be described with reference to FIG. Intake pressure signal P _B output from the intake negative pressure detector 10 is input to the A / D converter 101, and converted into a digital amount in a predetermined relationship.

The engine speed signal N output from the engine speed detector 8 is input to the f / D converter 102 and digitized.

The digital arithmetic circuit 103 receives the outputs of the A / D converter 101 and the f / D converter 102, digitally filters the digital information, and reads the signals [N] and [P _B ] is output.

The storage circuit 104 stores the engine speed N and the intake pressure signal P
_The data for determining signals to be output to the EGR control valve 12 in a plurality of operating states of the engine which are two-dimensionally divided by _B are stored.

That is, in the case of the EGR control valve 12 that moves by the negative pressure diaphragm, if the negative pressure supplied to the diaphragm is controlled by the time ratio of opening and closing the solenoid valve, data corresponding to the time ratio (duty) of opening and closing is stored. I have.

Signal for reading corresponding to the memory circuit 104 to the engine speed signal N and the intake pressure signal P _B [P _B], the data is read by inputting the [N], the pulse calculating output circuit 105 A pulse signal having a duty corresponding to the read data is generated in the pulse calculation output circuit 105 and output to the EGR control valve 12, and the control of the EGR amount is performed according to the operating state of the engine. Done.

Next, the operation of the main components of the present invention will be described with reference to FIGS. FIG. 3 is a characteristic diagram showing the relationship between the sensor output I _P and the oxygen concentration Co ₂ for delivering the oxygen sensor 21. Sensor output I _P for delivering the oxygen sensor 21 is input to the computer 22, the oxygen concentration corresponding within the computer 22 are calculated.

FIG. 4 is a characteristic diagram showing a relationship between the oxygen concentration Co ₂ and the EGR rate (EGR amount / intake amount of the engine). After the oxygen concentration Co ₂ is calculated according to this characteristic diagram, the EGR is similarly performed. The rate K is calculated in the computer 22.

Another input signal to the computer 22, i.e., the intake pressure signal P _B and the engine speed signal N, as shown in FIG. 5, the same process as internal EGR control circuit 14 is performed.

In FIG. 5, the arithmetic conversion circuit 210 includes an oxygen sensor 2
The EGR rate K 1 of the sensor output I _P is calculated in the manner described above, and sends the calculation result to the digital arithmetic circuit 213.

Digital arithmetic circuit 213 outputs a signal (E) for reading the memory circuit 204 of the EGR ratio K from the sensor output I _P of the oxygen sensor 21 by entering the EGR ratio K is calculated in the manner described above in Operation I do.

The storage circuit 204 stores the engine speed N and the intake pressure signal P
_B and two-dimensionally, and further stores data for determining the ignition timing in a plurality of operating states of the engine, which is divided by the EGR rate K.

The storage circuit 204 stores the engine speed N and the intake pressure signal P
A signal for reading data relating to _B and the EGR rate K [P _B ],
When [N] and [E] are input, the data stored in the storage circuit 204 at the location corresponding to these readout signals is read out and sent to the pulse arithmetic circuit 205.

The pulse calculation circuit 205 sends an energization pulse signal of the ignition coil 18 to the ignition drive device 19 using the output signal CA of the crank angle sensor 20 as a reference angle signal so that an ignition spark is generated in the ignition plug 18 at the ignition timing based on the above data. The ignition drive device 19 is driven, and the ignition drive device 19 causes the spark plug 18 to generate an ignition spark at a predetermined timing.

In this embodiment, as the control parameters of the engine,
Although the case of ignition timing has been described, even if this is replaced with a control parameter called air-fuel ratio, the engine control related to the air-fuel ratio of the engine with EGR added is almost the same configuration and operation except for the last operating means. The device can be realized.

〔The invention's effect〕

As described above, the present invention relates to the rotational speed of the internal combustion engine,
According to the intake pressure and the intake oxygen concentration, data indicating the optimal ignition timing based on the crank angle of the internal combustion engine is stored in the storage means, and the rotation speed detected by the rotation speed detection means, the intake pressure detection means The data indicating the optimum ignition timing according to the detected intake pressure and the intake oxygen concentration detected by the oxygen concentration detecting means is extracted from the storage means, and the control means based on the data indicating the optimum ignition timing. Since the ignition signal is output to the ignition means based on the crank angle detected by the crank angle detection means, there is almost no change over time even when used for a long time, and highly accurate engine control can be performed. In addition, the purification performance of the exhaust gas and the fuel efficiency are improved. Further, the data indicating the optimum ignition timing may be extracted according to the detection values detected by the various detection means, and there is no need to perform an operation or the like, and there is an effect that the processing can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of an engine control device of the present invention, FIG. 2 is a block diagram showing an internal configuration of an EGR control circuit in the embodiment, and FIG. shows the relationship between the oxygen concentration Co ₂ to oxygen sensor output I _P for the described oxygen concentration Co ₂ pairs EGR rate K of Fig. 4 according to the exemplary embodiment
FIG. 5 is a diagram showing an internal configuration of the computer in the embodiment. 1 ... engine body, 2 ... intake manifold, 3 ...
Exhaust manifold, 4 ... fuel supply device, 5 ... throttle valve, 8 ... engine speed detector, 10 ... intake pressure detector, 11 ... EGR passage, 12 ... EGR control valve, 14 ...
EGR control circuit, 18 spark plug, 19 spark plug drive device, 20 crank angle sensor, 21 oxygen sensor, 22 computer. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] An exhaust gas recirculation means for adjustably recirculating a part of exhaust gas of the internal combustion engine to an intake system and mixing the exhaust gas with intake air; a rotational speed detecting means for detecting a rotational speed of the internal combustion engine; Intake pressure detecting means for detecting an intake pressure of the internal combustion engine, oxygen concentration detecting means for detecting an intake oxygen concentration of the internal combustion engine, crank angle detecting means for detecting a crank angle of the internal combustion engine, and rotation of the internal combustion engine Storage means for storing data indicating the optimum ignition timing based on the crank angle of the internal combustion engine in accordance with the number, the intake pressure and the intake oxygen concentration; the rotational speed detected by the rotational speed detecting means; Data indicating the optimum ignition timing according to the intake pressure detected by the pressure detection means and the intake oxygen concentration detected by the oxygen concentration detection means is extracted from the storage means. Based on the data indicating the optimal ignition timing engine controller and a control means for outputting an ignition signal to the ignition means based on the crank angle detected by the crank angle detecting means.