JPH0737773B2 - Engine fuel controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine that detects atmospheric pressure and determines the fuel injection amount to be supplied to the engine without using an atmospheric pressure sensor. .

[Conventional technology]

A conventional fuel control device for an engine is an atmospheric pressure sensor that is linked to an accelerator pedal and is separate from a pressure sensor that detects an intake manifold pressure P in an intake passage downstream from a throttle valve that limits an intake amount to the engine by an absolute pressure. Based on the atmospheric pressure detection value detected by the atmospheric pressure sensor, it is determined whether the engine is in the enrichment mode, which is one of the operation modes, and the fuel injection amount supplied to the engine is pulsed according to the determination result. It was decided by the time width of.

[Problems to be Solved by the Invention]

Since the conventional engine fuel control device is configured as follows, there is a problem that the device itself becomes expensive because an expensive atmospheric pressure sensor is used.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a fuel control device for an engine that can determine a fuel injection amount according to atmospheric pressure without using an atmospheric pressure sensor. .

[Means for Solving the Problems]

The engine fuel control device according to the present invention includes a pressure sensor for detecting the intake manifold pressure, a cranking detecting means, and a change amount of the pressure for a predetermined period within a period from when the power is turned on to when the cranking detecting means detects. A pressure change detection means for detecting that the pressure change is below a predetermined value, a storage means for storing the pressure signal of the pressure sensor as an atmospheric pressure detection value at the time of this detection, and a predetermined value smaller than the atmospheric pressure detection value when the engine is not started. When the pressure signal increases from the value, the enrichment control means for determining the enrichment mode and increasing the fuel supply amount is provided.

[Work]

The engine fuel control device according to the present invention reads the intake manifold pressure equal to the atmospheric pressure before engine rotation from the pressure sensor as the atmospheric pressure detection value used for the enrichment mode determination for increasing the fuel supply amount in the enrichment mode. The amount of fuel supply can be accurately determined.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The drawing shows one embodiment of the present invention, in which 1 is a well-known engine mounted on a vehicle, 2 is an intake manifold of the engine 1, and 2A is an intake manifold 2 connected to an upstream port of the intake manifold 2. An intake pipe main body that constitutes the intake pipe, 3 is an air cleaner installed at the inlet of the intake pipe main body 2A, and 4 is an injector that injects and supplies fuel into the intake pipe main body 2A. Reference numeral 5 is a throttle valve that is provided in the intake pipe main body 2A and limits the amount of intake air to the engine 1 by adjusting the opening degree of the intake passage. 5A is linked to the throttle valve 5 and corresponds to the opening degree of the throttle valve 5. For example, a potentiometer-type throttle opening sensor 6 that outputs an analog voltage is installed in the intake pipe main body 2A downstream from the throttle valve 5, detects the intake manifold pressure P by absolute pressure, and measures the magnitude according to the detected pressure. Is a pressure sensor that outputs a pressure signal of. Further, 7 is a cooling water temperature sensor that detects the cooling water temperature WT of the engine 1, 8 is an exhaust manifold of the engine 1, 9 is an air-fuel ratio sensor that detects the oxygen concentration of the exhaust gas in the exhaust manifold 8, and 10 is the purification of the exhaust gas. It is a three-way catalytic converter. Reference numeral 11 is an ignition coil that supplies a high voltage to an ignition plug (not shown) of the engine 1, 12 is an igniter for energizing the ignition coil 11 when turned on, and 13 is turned on / off to drive the engine 1 for starting. This is a cranking switch that turns on / off the operation of a starter (not shown) and outputs an on / off signal. Reference numeral 14 denotes various parameters obtained by detecting each state of the engine 1 and the battery voltage V _B , performs various determinations and calculations based on these parameters and preset data, and represents the atmospheric pressure. It is a control device that reads the atmospheric pressure detection value, calculates the fuel injection amount, etc., and performs control in accordance therewith.

Next, the internal configuration of the control device 14 will be described in detail with reference to FIGS. 2 and 3. In FIG. 2, reference numeral 100 denotes a microcomputer, which is a CPU 200 that executes the flow shown in FIG. 3, a counter 201 that functions as a timer, a timer 202 that measures the rotation cycle of the engine 1, and an A that converts an analog signal into a digital signal. A / D converter 203, an input port 204 for inputting and transmitting a digital signal, a non-volatile RAM 205 functioning as a work memory, a flow shown in FIG. 3 stored in a program, and data for comparison / judgment and calculation. And a ROM 206 storing therein, an output port 207 for outputting the calculated fuel injection amount and the like, a common bus 208 for commonly connecting the above respective components, and the like. Reference numeral 101 is connected to a connecting portion between the primary coil end of the ignition coil 11 and the collector of the transistor of the igniter 12, and for example, a first input for inputting an ignition signal for detecting the engine speed N _E to the microcomputer 100. An interface circuit 102 is a throttle opening sensor 5A, a pressure sensor 6, a cooling water temperature sensor 7, an air-fuel ratio sensor 9 and an analog output signal from a battery 16 via a key switch 15 which will be described later and an A / D converter 2
2nd input interface circuit to be introduced in 03
Reference numeral 103 is a third input interface circuit for inputting an ON / OFF signal of the cranking switch 13 and other signals. 104 is an output interface circuit connected between the output port 207 and the injector 4, etc., 105 is connected to the side of the battery 16 whose side is grounded via the key switch 15, and supplies power to the microcomputer 100.
Power circuit, 106 is always connected to the side of battery 16 RAM20
It is a second power supply circuit that supplies power to 5.

Next, the operation executed by the CPU 200 in the microcomputer 100 will be described.

First, when the key switch 15 is turned on, a voltage is applied from the battery 16 to the first power supply circuit 105. First power supply circuit 105
Applies a constant voltage to the microcomputer 100, and the control device 14 starts operating. First, at the start of the operation, the initialization is performed, for example, the timer is set to 0, that is, the counter.
201 is reset to 0. When this operation is started, an interrupt is issued at predetermined intervals, and the flow of the interrupt routine shown in FIG. 3 is repeatedly executed.

First, in step 301, the engine speed N _E is calculated based on the measurement data of the timer 202 that measures the rotation cycle of the engine 1, and is stored in the RAM 205. The timer 202 receives the ignition signal generated when the igniter 12 changes from on to off through the first input interface circuit 101 from the igniter 12 to generate m times from (m-1) times of ignition. Measure the time until ignition. This measurement data is stored in the RAM 205 by another routine. Next, at step 302, a pressure signal representing the intake manifold pressure P from the pressure sensor 6 and a throttle opening signal representing the throttle opening θ from the throttle opening sensor 5A are sent to the second input interface circuit 102 and the A / D converter. It is read sequentially via 203 and stored in RAM 205. Next step
In step 303, the voltage of the battery 16 is converted into a digital value in the same manner as in step 302, the battery voltage V _E is read, and RA
Stored in M205. Then in step 304, the RAM 205
Based on the signals representing the engine speed N _E and the intake manifold pressure P read from, the volumetric efficiency C _EV of the engine 1 which has been experimentally obtained in advance as a function of the engine speed and the intake manifold pressure is calculated to calculate the RAM 205.
Store in. Next, in step 305, the basic pulse width T _PWO, which is the basic time for fuel injection, is set to K (coefficient) × P.
(Intake manifold pressure) × C _EV (volumetric efficiency) is calculated by the calculation formula, and the result is stored in the RAM 205. However, in the above equation, the value of the coefficient K is read from the ROM 206. Next, in step 306, the air-fuel ratio sensor 9
Is in an active state, that is, whether the output signal of the air-fuel ratio sensor 9 changes within a predetermined time (or the level of the cooling water temperature WT detected by the cooling water temperature sensor 7, etc.). Determine if the condition is met.
If the feedback condition is satisfied in step 306, the feedback correction term C of the fuel injection time is calculated in step 307 by the proportional-plus-integral control according to the output of the air-fuel ratio sensor 9.
_FB is calculated and stored in RAM 205. Meanwhile, step
If the feedback condition is not satisfied at 306, step 3
Go to 08 and set the correction term C _FB to 1 in RAM205.

After the process of step 307 or 308, the process proceeds to next step 309. In step 309, it is determined whether the ignition signal from the igniter 12 has been input even once. Proceed to step 310, where the ignition signal must have been input at least once. In step 310, since the signal from the cranking switch 13 is being input through the third input interface circuit 103, it is determined whether or not the cranking switch 13 is off. If the cranking switch 13 is off, the routine proceeds to step 311, the battery voltage V _B is read from the RAM 205, and it is determined whether or not the battery voltage V _B is 8 V or higher. If the battery voltage V _B is 8 V or higher, the routine proceeds to step 312, where the counter 201 is incremented and the elapsed time of the timer is increased. After step 312, the process proceeds to step 313, in which it is determined whether the elapsed time of the timer has reached 0.1 seconds, that is, whether the count value of the counter 201 has reached a predetermined value. Step 0.1 if 0.1 seconds has not elapsed
From RAM 205 proceeds to 14 reads the pressure signal representative of the intake manifold pressure P by detecting the maximum value P _M a _X and a minimum value P _MIN stored in the RAM 205.

When it is determined in the above step 313 that the elapsed time of the timer is 0.1 seconds, the routine proceeds to step 315, and in this step, the intake manifold pressure P is determined from the RAM 205.
The maximum value P _M ax and a pressure signal indicating the minimum value P _MIN reads the pressure variation _{ΔP (= P M ax-P} MIN) , for example 20mm of
It is determined whether or not the specified pressure of Hg is exceeded. If the pressure change amount ΔP is 20 mmHg or less, the process proceeds to step 316, and in this step, the pressure signal indicating the intake manifold pressure P is read from the pressure sensor 6 and stored in the RAM 205 as the atmospheric pressure detection value indicating the atmospheric pressure P _A. To do.

In step 310 above, the cranking switch 1
If it is determined that 3 is on, or if the battery voltage V _B is less than 8 V in step 311, the process proceeds to step 317 and the counter 201 is reset to 0.

When it is determined in step 309 that the ignition signal has been input even once, after the processing in step 317, when it is determined in step 315 that the pressure change ΔP exceeds 20 mmHg, and after the processing in step 316. If, then proceed to step 318. In step 318, it is determined whether the engine 1 is in the starting mode. RAM2
If the engine speed N _E of the engine speed signal read from 05 is less than or equal to the engine speed N ₁ shown in FIG. Step 31
If it is determined that the mode is not the starting mode in step 8, the process proceeds to step 319, the atmospheric pressure detection value representing the atmospheric pressure P _A is read from the RAM 205, and the set value corresponding to the predetermined pressure ΔP _E is read from the ROM 206. The lower limit pressure P ₀ of the enriched mode shown is calculated according to the arithmetic expression of P ₀ = P _A −ΔP _E , and the enriched mode pressure threshold value corresponding to the lower limit pressure P ₀ of the enriched mode is calculated. In step 320 after step 319,
It is determined whether or not the intake manifold pressure P of the pressure signal read from the RAM 205 is equal to or higher than the lower limit pressure P _{0 in the} enrichment mode, that is, whether or not the enrichment mode. If it is determined in step 320 that the mode is enriched, RAM20 is set in step 321.
The fuel injection pulse width T _PW is calculated by multiplying the basic pulse width T _PWO read from 5 with the feedback correction term C _FB (however, 1 in the enrich mode) and the enrich coefficient C _ER in the enrich mode read from ROM 206. To do.

On the other hand, if it is determined in step 318 that the mode is the start mode or if it is determined in step 320 that the operation mode is not the enriched mode but the air-fuel ratio feedback control is possible, the process proceeds to step 322, and the basic pulse width T _PWO and feedback correction are performed from the RAM 205. The term C _FB is read and multiplied to calculate the fuel injection pulse width T _PW .

After the processing of step 321 or 322, the process proceeds to the next step.

Although the engine speed is used for the determination of the start mode, the cooling water temperature level determination may be added in addition to this.

5 and 6, the horizontal axis represents time and the vertical axis (a).
Is the intake manifold pressure P, (b) is the on / off signal from the key switch 15, (c) is the on / off signal of the cranking switch 13, and (d) is the igniter.
Ignition signals from 12 are shown respectively.

In FIG. 5, a pressure signal representing the atmospheric pressure P _A is read from the pressure sensor 6 without any malfunction. That is, the time point
t ₀ key switch 15 is turned on by, while from time t ₀ until 0.1 seconds has elapsed time point t ₁ is OFF cranking switch 13, even once the ignitor 12 have not entered the ignition signal. Therefore, the amount of change in the intake manifold pressure P during this period is small and is 20 mmHg or less, so P at the time t ₁
Atmospheric pressure P _{A at} point (t ₁ ) is detected. At this time, the engine 1 has not yet rotated and is not inhaling, and there is no pressure loss, so the pressure detection error is extremely small. Time after time t ₁ t ₂
The cranking switch 13 changes from off to on, and the operation of the engine 1 starts at this time. The later time point t ₂ air repeatedly inhaled through the intake pipes 2A and the intake manifold 2 from an air cleaner 3 engine 1 is rotated, the time
Since the ignition signal is input at the time when the ignition signal is generated at time points t ₃ , t ₄ , t ₅ ... After t _2, the explosion process is performed and the well-known process of the engine 1 is repeated, the intake manifold pressure P varies greatly. Become. Accordingly, the pressure varies as time t ₂ later
If the ignition signal exceeds 20 mmHg, or if the ignition signal is input even once even after the time t ₃ , the detection error becomes large, and therefore the pressure signal from the pressure sensor 6 is not the atmospheric detection value. Further, since the time t ₀ to the same t ₁ exceeds 0.1 seconds, the pressure signal is not the atmospheric pressure detection value.

FIG. 6 shows a case where the signal from the key switch 15 is temporarily turned off and then turned on again due to some cause, for example, a momentary power failure. Key switch while engine 1 is rotating
The signal from 15 turns off at time t ₆ and immediately thereafter at time t ₇
Even when the engine 1 is turned on again, the intake manifold pressure P is considerably negative because the intake manifold pressure P is continuously repeated due to the running-on of the engine 1, and the intake manifold pressure P is considerably negative pressure than the atmospheric pressure indicated by the alternate long and short dash line. . In this case, the cranking switch 13 is also certainly turned off at time t ₆ even when t ₈ of time lapse t ₇ after 0.1 second off, also at the time point t ₈ even once inputs the ignition signal I haven't. However, the fluctuation of the intake manifold pressure P
Since it exceeds 20 mmHg, the intake manifold pressure P at point P (t ₈ ) at time t ₈ is not detected and read as the atmospheric pressure detection value.

In the above embodiment, the pressure change amount ΔP of the difference between the maximum value P _MAX and the minimum value P _MIN of the intake manifold pressure P was compared with the predetermined pressure. You may compare with a predetermined pressure.

Also, in step 316, the intake manifold pressure P is not newly read from the pressure sensor 6 and step 302
The intake manifold pressure read in may be read from the RAM 205 and used as the atmospheric pressure detection value.

〔The invention's effect〕

As described above, according to the present invention, if the intake manifold pressure fluctuation is equal to or less than the predetermined value during the predetermined period from the time when the power is turned on to the time when the cranking switch is turned on, the pressure from the pressure sensor that has detected the intake manifold pressure. The signal is stored as the atmospheric pressure detection value, and when the output of the pressure sensor increases by a value smaller than the atmospheric pressure detection value by a predetermined value, the enrichment mode is determined and the fuel supply amount is increased. There is an effect that can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of the entire apparatus according to an embodiment of the present invention,
FIG. 2 is a block diagram showing a configuration of a control device and the like in the device, FIG. 3 is a flow diagram showing an operation flow of a CPU in the control device, FIG. 4 is an explanatory diagram showing an operation mode, and FIG. 6 and 6 are timing charts showing the states of various parts of the apparatus. In the figure, 1 ... Engine, 2 ... Intake manifold, 2A ... Intake pipe body, 4 ... Injector, 5 ... Throttle valve, 6 ... Pressure sensor, 9 ... Air-fuel ratio sensor,
11 ... Ignition coil, 12 ... Igniter, 13 ... Cranking switch, 14 ... Control device, 15 ... Key switch,
16 …… Battery, 100 …… Microcomputer, 101〜
103 ... First to third input interface circuits, 104 ... Output interface circuits, 105, 106 ... First and second power supply circuits. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 59-201938 (JP, A) JP 59-37437 (JP, A) JP 58-133433 (JP, A) JP 58- 65950 (JP, A)

Claims (1)

[Claims] 1. A pressure sensor for detecting an intake manifold pressure in an intake passage downstream from a throttle valve for limiting an intake amount to an engine by an absolute pressure, and a starter for driving the engine for starting. And a cranking detecting means for detecting that the change in pressure detected by the pressure sensor is below a predetermined value in a predetermined period within a period from power-on to detection by the cranking detecting means. Pressure change detection means, storage means for receiving the detection signal of the pressure change detection means and storing the pressure signal from the pressure sensor as an atmospheric pressure detection value, and the atmospheric pressure detection value when the engine is not in the start mode but in an operation mode. When the pressure signal of the pressure sensor increases from a value smaller than a predetermined value from the above, the fuel supply amount is increased by determining the enrichment mode. Fuel control device for an engine that includes a Nritchi control means.