JPH0357295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine control device that controls fuel injection amount and ignition timing in accordance with intake pipe pressure detected by a pressure sensor.

[Conventional technology]

In this type of engine, especially when controlling the fuel injection amount, the responsiveness of the pressure sensor is not sufficient in a region where the pressure changes rapidly.

The detection signal of the pressure sensor is output through a low-pass filter and has a delay in order to remove ripples due to the influence of intake pulsation.

Control of fuel injection amount is possible even in multi-cylinder engines.
The control is not performed for each cylinder's intake stroke, but is intermittently controlled for a plurality of cylinders at once, resulting in a delay in control during acceleration/deceleration operation.

Even in independent injection engines where fuel is injected into each cylinder, the required injection amount is determined based on the pressure signal when the piston approaches the intake bottom dead center, but the actual calculation of the injection amount is based on that. Much earlier than that.

As a result, during acceleration operation, the required amount of fuel cannot be injected and the air-fuel ratio becomes over-lean, and during deceleration operation, the fuel injection amount becomes excessive and the air-fuel ratio There was a problem with overloading.

Therefore, a phase control means is provided to perform predetermined phase advance processing on the intake pipe pressure signal detected by the pressure sensor, and the fuel injection amount is calculated based on the phase advance processed signal. The present applicant is considering performing fuel injection based on the injection amount. According to this method, since there is no delay in control, it is possible to prevent over-conversion or over-lean of the air-fuel ratio during acceleration/deceleration operation.

However, ignition timing control is not performed intermittently like fuel injection amount control, but is performed for each ignition, so ignition timing is calculated based on the signal that has undergone phase advance processing, and is based on the calculated ignition timing. If ignition is performed during acceleration, the pressure after the phase advance process will be higher than the actual intake pressure, so the advance angle will be smaller than the appropriate value, and sufficient engine output will not be obtained. Furthermore, during deceleration operation, the pressure after the phase advance process is lower than the actual intake pressure, so the advance angle becomes larger than the appropriate value and knocking occurs.

[Purpose of the invention]

In view of these conventional problems, an object of the present invention is to use a phase-advanced signal to calculate the fuel injection amount, but to calculate the ignition timing.
By using phase advance processing or signals,
The objective is to optimally control both fuel injection amount and ignition timing based on intake pipe pressure.

[Structure of the invention]

As shown in FIG. 1, the engine control device according to the present invention includes a pressure detection means a for detecting the intake pipe pressure downstream of the throttle valve of the engine;
ignition timing calculation means b for calculating ignition timing based on the intake pipe pressure signal detected by the pressure detection means; and performing a predetermined phase advance process on the intake pipe pressure signal detected by the pressure detection means. a phase control means c; a fuel injection amount calculation means d for calculating the fuel injection amount based on the output signal of the phase control means; an ignition means e for igniting the air-fuel mixture based on the output of the ignition timing calculation means; and injection means f for injecting fuel based on the output of the amount calculation means.

〔Effect of the invention〕

According to the present invention, the fuel injection amount is calculated based on the intake pipe pressure signal that has been subjected to phase advance processing, and the ignition timing is calculated based on the intake pipe pressure signal that has not been subjected to phase advance processing. Both the fuel injection amount and ignition timing can be optimally controlled.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an electronically controlled fuel injection engine as an example. In the same figure, 1
0 represents the engine body, 12 represents the intake passage, 14 represents the combustion chamber, and 16 represents the exhaust passage. The flow rate of intake air taken in through an air cleaner (not shown) is controlled by a throttle valve 18 which is also linked to an accelerator pedal (not shown). Intake air that has passed through the throttle valve 18 is guided into the combustion chamber 14 via a surge tank 20 and an intake valve 22.

A port 25 is open in the intake passage 12 downstream of the throttle valve 18, for example, in a portion of the surge tank 20, and this port 25 is provided with a voltage that detects the absolute pressure inside the intake pipe and applies a voltage corresponding to the detected value. A pressure sensor 24 that generates . The output voltage of this pressure sensor 24 is sent to a control circuit 28 via line 26.

The fuel injection valve 30 is actually provided for each cylinder, and is controlled to open and close in response to electrical drive pulses sent from the control circuit 28 via a line 32, and sent from a fuel supply system (not shown). Pressurized fuel is intermittently injected into the intake passage 12 near the intake valve 22.

The igniter 58 including the ignition coil receives a pulsed drive signal with regulated ignition timing and closing angle from the control circuit 28 via a line 59.
A high-pressure ignition signal is generated, and the ignition signal is distributed via a distributor 38 to a spark plug 39 provided for each cylinder.

The exhaust gas after being burned in the combustion chamber 14 is discharged into the atmosphere via the exhaust valve 34 and the exhaust passage 16, and further via the catalytic converter 36.

Pulse signals are output from crank angle sensors 40 and 42 provided in the distributor 38 each time a crankshaft (not shown) rotates by 30° and 360°, respectively, and the pulse signals for each 30° crank angle follow a line 44. , the pulse signal for each 360° crank angle is line 46.
are sent to the control circuit 28 via the respective channels.

In the intake passage 21 upstream of the throttle valve 18,
An intake air temperature sensor 48 is provided to detect the temperature of the intake air, and its output voltage representative of the sensed intake air temperature is fed to the control circuit 28 via line 50.

The engine cylinder block is equipped with a water temperature sensor 52 for detecting the coolant temperature, the output voltage representing the detected coolant temperature being fed to the control circuit 28 via line 54.

FIG. 3 shows an example of the configuration of the control circuit 28 shown in FIG. In the figure, the pressure sensor 24, the intake air temperature sensor 48, the water temperature sensor 52, the crank angle sensors 40 and 42, the igniter 58, and the fuel injection valve 30 provided for each cylinder are each represented by blocks.

The output voltage of the pressure sensor 24 is applied to a low-pass filter 56 to remove ripples due to intake pulsation, and then converted into an analog-digital (A/D) signal.
into a converter 60. low pass filter 5
6 is the simplest combination of a resistor and a capacitor in the example shown in FIG. 3, but various other known configurations can be applied. Intake temperature sensor 4
8 and the output voltages of the water temperature sensor 52 are also sent to the A/D converter 60. The A/D converter 60 has an analog multiplexer function, selects the signal from each sensor according to the instruction signal from the microprocessor (MPU) 62, A/D converts it, and converts it into two signals.
Get the advance signal.

A pulse signal every 30 degrees of crank angle from the crank angle sensor 40 is transmitted to an input/output circuit (I/O circuit) 64.
is sent to the MPU62 via the crank angle 30°
The signal serves as an interrupt request signal for each interrupt processing routine, and also serves as a clock for incrementing a timing counter provided in the I/O circuit 64. In addition, the crank angle 360° from the crank angle sensor 42
Each pulse signal serves as a reset signal for the above-mentioned timing counter. A timing signal obtained from this timing counter is sent to the MPU 62 and becomes an interrupt request signal for the ignition processing routine.

A well-known fuel injection control circuit including a resist etc. is provided in the input/output circuit (I/O circuit) 66, and based on binary data regarding the injection pulse width sent from the MPU 62, injection having the pulse width is determined. Form a pulse signal. This injection pulse signal is transmitted to the fuel injection valve 3 via a drive circuit (not shown).
0 and energizes it. Thereby,
An amount of fuel is injected according to the pulse width of the injection pulse signal. In addition, an ignition timing control circuit similar to the fuel injection control circuit is provided in the I/O circuit 66, and the advance angle and closing angle are determined based on binary data regarding the ignition timing and closing angle sent from the MPU 62. form an ignition pulse signal having a This ignition pulse signal is sent to the igniter 58 via a drive circuit (not shown) and energizes it. As a result, an ignition signal corresponding to the ignition pulse signal is generated, and ignition is performed in the ignition plug 39 of each cylinder.

The A/D converter 60 and I/O circuits 64 and 66 include an MPU 62 and random access memory (RAM), which are the main components of the microcomputer.
68 and a read-only memory (ROM) 70 via a bus 72.
Data is transferred via.

The ROM 70 stores in advance a main processing routine program, an interrupt processing routine program for every 30 degrees of crank angle, and other programs, as well as various data, tables, etc. necessary for these arithmetic operations.

Next, the operation of the above-mentioned microcomputer will be explained using the flowcharts shown in FIGS. 5 to 8.

The MPU 62 instructs the A/D converter 60 to start the A/D converter at predetermined intervals, and the data representing the intake air temperature THA and the cooling water temperature THW are as follows.
It is taken into the computer by the A/D conversion completion interrupt from the A/D converter 60 and is stored as is.
Stored in RAM68. On the other hand, when the A/D conversion of the channel regarding the intake pipe pressure is completed, the data is stored in the RAM 68, and the microcomputer executes the interrupt processing shown in FIG.

First, in step 80, the binary signal value after A/D conversion is input into the computer as PMA/D.
Next, in step 81, the following equation is calculated as smoothing processing.

PMDi=PMDi- ₁ +K (PMA/D - PMDi- ₁ ) ...(1) Here, PMDi- ₁ is the value of the previous interrupt
It represents PMDi, where K is a constant. Note that this PMDi is made to match the current PMA/D during an initial processing routine that is performed immediately after the engine is started. In the next step 82, the intake pipe pressure used to calculate the fuel injection pulse width is
Calculate PMOS from the following formula.

PMOS=2PMA/D-PMDi =PMA/D+(PMA/D-PMDi)...(2) Next, in step 83, PMDi is set to PMDi- _1.
It is stored in the RAM 68 as . Also, PMOS
Store in RAM68. Through the above processing, the phase advance processing in the present invention is performed.

FIG. 4 is a waveform diagram illustrating the effect of the arithmetic processing in steps 81 and 82 in the processing routine of FIG. 5 described above. In the figure, PM corresponds to the output of the pressure sensor 24, and PMi corresponds to the output of the low-pass filter 56. Therefore, this corresponds to the output of the A/D converter 60.
It corresponds to the conversion output PMA/D from . this
PMA/D is smoothed in step 81 to become PMDi. The difference between this PMDi and PMA/D (PMA/D - PMDi) is determined in step 82.
Final intake pipe pressure added to PMA/D
Becomes PMOS. Note that (PMA/
D-PMDi) corresponds to the shaded area in FIG. As mentioned above, by performing phase advance processing, it is possible to compensate for the delay in the intake pipe pressure signal and the delay in fuel injection amount control during acceleration/deceleration operation, so the optimal amount of fuel can be injected even during acceleration/deceleration operation, and the This can prevent fuel ratio deviations.

Hereinafter, a description will be given of how fuel injection control is performed from the intake pipe pressure signal and other parameters obtained as described above.

Data representing the rotational speed NE of the engine is obtained, for example, by the processing routine shown in FIG. In response to a pulse signal outputted from the crank angle sensor 40 at every 30° crank angle, the interrupt process shown in FIG. 6 is performed. First, in step 90,
The value of the free run counter provided in the MPU 62 is read and the value is set as _C30 . In the next step 91, the difference ΔC between the value C ₃₀ ' read during the previous interrupt processing and the current value C ₃₀ is calculated as ΔC=C ₃₀ −
C ₃₀ ', and in step 92, the reciprocal of the difference ΔC is calculated to obtain the rotational speed NE. That is,
A calculation of NE=A/ΔC is performed in step 92. However, A is a constant. The speed NE thus obtained is stored in the RAM 68. next step
In 93, C ₃₀ is stored in the RAM 68 as C ₃₀ '.

On the other hand, the MPU 62 executes the process shown in FIG. 7 during the main processing routine. First, step
At 100 and 101, intake air temperature from RAM68
Import THA and cooling water temperature THW data, and adjust correction coefficients FTHA and FTHW according to these data.
Each is calculated from a mathematical formula or table.
Since this method of obtaining is well known, detailed explanation will be omitted. Next, in steps 102 and 103, the intake pipe pressure PMOS and rotational speed NE data, which have been subjected to phase advance processing in the processing routine of FIG. 5, are stored in the RAM.
68, and the basic injection pulse width TP corresponding to these data is determined using interpolation calculation from a table of basic injection pulse width TP for the rotational speed NE and the intake pipe pressure PMOS. This method is also known. Next, in step 104, the final fuel injection pulse width TAU is changed to the basic injection pulse width.
It is calculated from TP, the above-mentioned correction coefficients FTHA and FTHW, other correction coefficients α and β, and the invalid injection time TV of the fuel injection valve 30 according to the following formula.

TAU=TP・FTHA・FTHW・α+β+TV The TAU obtained in this way is stored in the RAM 68.

By determining the TAU, an injection pulse signal having a duration corresponding to the TAU is created by a known method, and the injection pulse signal is sent to the I/O circuit 66 to initiate fuel injection as described above. The valve 30 is driven to open and close.

Further, ignition timing control is performed by a processing routine shown in FIG. When the timing counter provided in the I/O circuit 64 generates a timing signal at a crank angle of 120°, the interrupt processing shown in FIG. 8 is performed. First, in steps 110 and 111,
The data of the cooling water temperature THW is read from the RAM 68, and the corrected advance angle θm corresponding to this data is determined from a mathematical formula or a table. Then step
112 and 113, intake pipe pressure PMA/D and rotation speed before phase advance processing are shown in Figure 5.
Load the NE data from RAM68, and calculate the basic advance angle θb and rotation speed according to these data.
The basic advance angle for NE and intake pipe pressure PMA/D is determined using interpolation calculation from the table of θb. In step 114, the final advance angle θ
is calculated from the basic advance angle θb and the corrected advance angle θm using the following equation.

θ=θb+θm The advance angle θ obtained in this way is
It is stored in 8.

An ignition pulse signal is created by a known method by determining the advance angle θ and calculating the closing angle by another routine, and further, as described above, the ignition pulse signal is input to the I/O igniter 58 generates an ignition signal.

As mentioned above, the basic injection pulse width TP, which determines the fuel injection amount, is the intake pipe pressure after phase advance processing.
The basic advance angle θb, which is determined using PMOS and determines the ignition timing, is determined using the intake pipe pressure PMA/D which is not subjected to phase advance processing. Therefore, fuel injection amount control and ignition timing control can be optimally performed during acceleration/deceleration operation.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. For example, the phase advance processing may be realized by an analog circuit.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims, Fig. 2 is a schematic diagram of an embodiment of the present invention, Fig. 3 is a block diagram of the control circuit of Fig. 2, and Fig. 4 is an intake pipe pressure according to the present invention. The signal characteristic diagrams in FIGS. 5 to 8 are flowcharts of part of the microcomputer control program. 10...Engine body, 12...Intake passage, 2
4...Pressure sensor, 28...Control circuit, 30...
Fuel injection valve, 40, 42... crank angle sensor,
56...Low pass filter, 58...Igniter, 60...A/D converter, 62...MPU, 6
4, 66...I/O circuit, 68...ROM, 70
……ROM.

Claims (1)

[Claims] 1. Pressure detection means for detecting the intake pipe pressure downstream of the throttle valve of the engine; and ignition timing calculation means for calculating the ignition timing based on the intake pipe pressure signal detected by the pressure detection means. , a phase control means that performs a predetermined phase advance process on the intake pipe pressure signal detected by the pressure detection means; a fuel injection amount calculation means that calculates the fuel injection amount based on the output signal of the phase control means; An engine control device comprising: ignition means for igniting an air-fuel mixture based on the output of the ignition timing calculation means; and injection means for injecting fuel based on the output of the fuel injection amount calculation means.