JPH045329B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for determining an abnormality in a reference crank angle position detection system of an internal combustion engine.

(Technical Background of the Invention) As a control method for an internal combustion engine, a reference pulse is generated corresponding to a predetermined crank angle in response to the rotation of a crankshaft, and a constant crank angle corresponding to a period shorter than the period of the reference pulse is used. There is a control method in which the ignition timing is electronically controlled using two input signals: a crank angle pulse generated by the engine.
A method of controlling ignition timing using the two input signals is disclosed in Japanese Patent Publication No. 30766/1983.

Of the above two input signals, the reference pulse is an extremely important signal for performing other controls, such as fuel injection control, or fixed ignition during low rotation during cranking or fail-safe, while the crank angle pulse Since the number of occurrences is small compared to the reference pulse, a noise signal is likely to be generated in the section where the reference pulse is not generated, which may cause malfunction.
For example, in a configuration in which a counter that counts the crank angle pulse is reset by the reference pulse, everything depends on the reference pulse, and even if the reference pulse is generated normally this time, it will not be generated normally the next time, and the counter that counts the crank angle pulse will be reset. If the counter is not reset, the engine cannot be controlled. Therefore, it is necessary to quickly detect an abnormality in the reference pulse and perform appropriate processing in the event of an abnormality to enable engine control.

(Object of the Invention) The present invention has been made in view of the above-mentioned points, and an object of the present invention is to determine an abnormality in a signal system input to an engine control device, particularly in a reference crank angle position detection system.

(Means for solving the problem) In order to achieve the above object, the present invention includes:
A reference pulse generated in response to a predetermined crank angle of a crankshaft of an internal combustion engine, and a crank angle pulse generated in response to a constant crank angle shorter than the period of the reference pulse, and at least two of these pulses are generated. a control device for controlling the internal combustion engine using two input signals, determines the occurrence of the reference pulse, starts counting the crank angle pulses by the reference pulse, and starts counting the crank angle pulses by the reference pulse; The process is continued until a predetermined value is reached regardless of the occurrence of the crank angle pulse, and it is determined whether the counted value of the crank angle pulse matches the predetermined value, and when it matches, the reference value is set between the previous and current crank angle pulses. To provide an abnormality determination method for a reference crank angle position detection system for an internal combustion engine, which determines whether a pulse is input or not, and determines that the reference pulse is abnormal when the reference pulse is not input. It is.

(Embodiment of the Invention) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows a sensor that detects the crank angle of an internal combustion engine. Two rotors 2 and 3 are arranged at a predetermined interval on a camshaft 1 that rotates once every two revolutions of the crankshaft. The rotor 2 has four protrusions 2a having a predetermined width at 90° in the circumferential direction, depending on the number of cylinders of the internal combustion engine, for example, four cylinders.
They protrude outward in the radial direction at equal intervals. The outer circumferential surface of the rotor 3 is provided with a constant interval narrower than the interval between the protrusions 2a of the circular rotor 2, for example, at a crank angle of 30°.
Therefore, the protrusions 3a are arranged at intervals of 15 degrees of rotation angle of the camshaft 1.
There are 24 projecting radially outwards.

The sensors 4 and 5 are composed of pick-up coils, for example, and are disposed at radially outward positions of the rotors 2 and 3 so as to be able to face each of the protrusions 2a and 3a with a slight gap. The second
Pulse T ₀₄ and T ₂₄ signals are generated as shown in Figures a and b. The rotor 2 and the sensor 4 constitute a reference pulse sensor 6, and the reference pulse sensor 6 is set at a predetermined crank angle of 90° (1/4 of the camshaft 1) for each cylinder in response to the rotation of the crankshaft. A pulse (hereinafter referred to as reference pulse) T ₀₄ signal is generated for each rotation (rotation).

The rotor 3 and the sensor 5 constitute a crank angle sensor 7, and the crank angle sensor ₇ generates pulses (hereinafter referred to as Generates a T ₂₄ signal (referred to as crank angle pulse). Then, based on the T ₀₄ pulse, it is determined that the T ₂₄ pulse generated immediately after the generation of the T ₀₄ pulse is, for example, a predetermined reference crank position.

FIG. 3 shows an outline of an electronic control device for carrying out the method of the present invention, and the reference pulse T ₀₄ signal and crank angle pulse T ₂₄ signal output from the reference pulse sensor 6 and crank angle sensor 7 are controlled by the electronic control device, respectively. The waveform is shaped into a square wave pulse by waveform shaping circuits 12 and 13 of 11, and then input to a central processing unit (hereinafter referred to as CPU) 16. This electronic control device 11 has other engine parameter signals such as a P _B sensor 8 that detects the absolute pressure P _B in the intake pipe, a Tw sensor 9 that outputs the engine water temperature Tw, and an intake air temperature T _A in the intake manifold of the engine.
Each detection signal (analog signal) output from the T _A sensor 10 etc. is corrected to a predetermined voltage level by the level correction circuit 14, and then converted into a corresponding digital signal by the analog-digital converter 15 and input to the CPU 16. .

The CPU 16 calculates the fuel injection time based on the engine parameter signals input from each sensor 6 to 10 according to various calculation programs stored in the ROM 18, and outputs the reference pulse T ₀₄ signal and crank angle pulse T ₂₄ signal. A fuel injection timing control signal and an ignition timing control signal are output at each predetermined stage of the _T24 pulse. The CPU 16 outputs a fixed ignition signal based on the T ₀₄ pulse when the engine speed is low, for example, 500 rpm or less. The RAM 17 temporarily stores various calculation results.

The drive circuit 19 controls the opening of the injection valves 20 to 23 of each cylinder according to the fuel injection timing control signal.
The ignition circuit 24 outputs an ignition signal in response to the ignition timing control signal, cuts off the current in the primary coil 25a of the ignition coil 25, generates a high voltage in the secondary coil 25b, and synchronizes with the rotation of the engine. The electric current is sequentially applied to the spark plugs of each cylinder via the rotating distributor 26.

By the way, since the reference pulse T ₀₄ signal occurs less frequently than the crank angle pulse T ₂₄ signal, there is a problem that noise is likely to occur (with a high probability) in the section where the pulse T ₀₄ signal is not generated. Further, the reference pulse T ₀₄ signal is an important signal for other controls such as the above-mentioned fuel injection amount control, ignition timing control, especially fixed ignition in a low engine speed range or during fail-safe operation. Therefore, the presence or absence of the reference pulse T ₀₄ signal is checked using the crank angle pulse T ₂₄ signal, which does not easily contain noise, to determine whether the reference pulse T ₀₄ signal is abnormal.

Hereinafter, a method for determining an abnormality in the reference pulse T ₀₄ signal will be described in detail with reference to the pulse T ₀₄ and T ₂₄ signals shown in FIG. 2 and the flowcharts shown in FIGS. 4 and 5.

First, in step 30 of the flowchart of FIG. 4, which is executed every time the reference pulse T ₀₄ signal is generated, a flag is set to indicate that the pulse T ₀₄ signal has been generated. Then pulse T ₂₄
A _T24 counter (stage counter) that counts the number of occurrences of the pulse _T24 signal in step 31 of the flowchart in FIG. 5, which is executed every time a signal is generated; an initial flag that is set in step 33 described later It is determined whether or not the pulse flag of the pulse T04 signal is set. If the answer is negative (No), the process proceeds to step 32, and it is determined whether or not the pulse flag of the pulse _T04 signal is set. If the answer to step 32 is negative (No), the program ends without performing any other operations.

If _the answer to step 32 is affirmative (Yes), that is, if _{the T 04 pulse} flag was set in step 30 of _FIG . At the same time as setting the pulse flag (step 33), the T ₀₄ pulse flag is reset, and then the value of the T ₂₄ counter is set to 0 (step 34), and the program ends. That is, at the beginning (at the start)
The value of the _T24 counter is set to 0 by the generation of the _T04 pulse.

T ₂₄ counter is a ring counter, which pulses T ₂₄
Each time a signal is input, the count is increased sequentially, and when it reaches a predetermined count value, for example, count value 5, it returns to 0, and the count value changes from 0 → 1 → 2 → 3 → 4 →
Repeat in the order of 5 → 0. Therefore, the T ₂₄ counter is automatically updated to 0 every six T ₂₄ pulses after being reset to 0 by the first T ₀₄ pulse at the start.

When the _T24 pulse is generated after the initial flag of the _T24 counter is set, the answer to the determination at step 31 becomes affirmative (Yes), and the _T24 counter counts up (step 35). In step 36, it is determined whether or not the value of the _T24 counter is 0. If the answer is negative (No), the program is terminated and the operation is repeated until the value of the _T24 counter becomes 0. When the answer to step 36 is affirmative (Yes), that is, the count value of the _T24 counter increases sequentially and reaches the predetermined value 5, and the current _T24 pulse causes it to reach 0.
When returning to step 37, it is determined whether or not the next _T04 pulse flag was set between the previous and current _T24 pulses (step 37), and if the answer is affirmative (Yes), the The flag set by the _T04 pulse is reset (step 38), and the program is terminated after diagnosing that there is no abnormality in the reference crank angle position detection system including the reference pulse _T04 sensor 6.

If the answer to step 37 is negative (No), that is,
When the count value of the T ₂₄ counter reaches the predetermined value due to the current T ₂₄ pulse and returns to 0, the previous and current values are
If the next T ₀₄ pulse is not generated between the T ₂₄ pulse and the next T 04 pulse, it is determined whether the engine rotation speed Ne is higher than the rotation speed Nf at which fail-safe (F/S) is performed (step 39), and the If the answer is negative (No), that is, if the engine is operating in an extremely low rotational speed range such as during cranking, when there is no need to perform failsafe, the initial flag of the _T24 counter is reset (step 40) and this program is executed. end. Furthermore, when the engine speed is extremely low in the first half, the engine rotation becomes unstable due to engine friction, etc., and as a result, the _T04 pulse signal and _T24 pulse signal generated are no longer reliable, and may be determined to be a malfunction. Therefore, in this case, it is not regarded as an abnormality and the above-mentioned failsafe is not performed.

When the answer to step 39 is affirmative (Yes), that is, when the engine speed Ne is higher than Nf and the engine is in a predetermined operating state, it is determined that the _T04 pulse is abnormal and the process proceeds to the failsafe subroutine. . In this fail-safe subroutine, since the T ₂₄ counter is composed of a ring counter as described above, for example, when the T ₂₄ counter shows a predetermined count value only by the T ₂₄ pulse, simultaneous fuel injection, fixed ignition, etc. It is also possible to perform a fail-safe operation, and furthermore, it is possible to generate an alarm or the like to notify the driver of an abnormality in the reference crank angle position detection system including the T ₀₄ sensor 6.

As a reference pulse sensor and a crank angle sensor, a slit is provided instead of a protrusion, and an emitter and a light receiver are provided facing each other through the slit to photoelectrically detect the crank angle position. Good too.

(Effects of the Invention) As explained above, according to the present invention, a reference pulse generated in response to a predetermined crank angle of the crankshaft of an internal combustion engine and a constant crank angle that is shorter than the period of the reference pulse are generated. a crank angle pulse generated by a controller, the controller for controlling the internal combustion engine using at least these two input signals determines the occurrence of the reference pulse; Start counting, count the crank angle pulses continuously until a predetermined value is reached regardless of the occurrence of the reference pulse, determine whether the counted value of the crank angle pulses matches the predetermined value, and determine whether the counted value of the crank angle pulses matches the predetermined value. When this happens, it is determined whether or not the reference pulse is input between the previous and current crank angle pulses, and when the reference pulse is not input, it is determined that the reference pulse is abnormal. Therefore, it is possible to detect abnormalities in the reference crank angle position detection system, including disconnection of the sensor that generates the reference pulse, and it is possible to perform appropriate processing based on this detection result, and continue engine control. becomes possible. Further, there is an advantage that the abnormality can be detected by a simple program without adding other devices such as an external counter.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a sensor that detects the crank angle of an internal combustion engine, Figure 2 is a timing diagram showing an example of a pulse signal generated from the sensor in Figure 1, and Figure 3 is a diagram showing an example of a sensor that detects the crank angle of an internal combustion FIGS. 4 and 5 are a block diagram showing one embodiment of an engine control device, and are flowcharts for carrying out a method for determining an abnormality in a reference crank angle position detection system of an internal combustion engine according to the present invention. 6... Reference pulse sensor, 7... Crank angle sensor, 11... Control device, 17... Drive circuit,
24...Ignition circuit, 20-23...Injection valve, 26
...Distributor, 27-30...Plug.

Claims (1)

[Claims] 1. A reference pulse generated in response to a predetermined crank angle of a crankshaft of an internal combustion engine, and a crank angle pulse generated in response to a constant crank angle shorter than the cycle of the reference pulse. a control device for controlling the internal combustion engine using at least these two input signals; Continuously perform counting until a predetermined value is reached regardless of the occurrence of the reference pulse, and determine whether the counted value of the crank angle pulse matches the predetermined value;
When they match, it is determined whether or not the reference pulse has been input between the previous and current crank angle pulses, and when the reference pulse has not been input, it is determined that the reference pulse is abnormal. A method for determining an abnormality in a reference crank angle position detection system of an internal combustion engine, characterized in that: 2. Abnormality in the reference crank angle position detection system of an internal combustion engine according to claim 1, wherein the determination as to whether or not the reference pulse is input is performed when the internal combustion engine is in a predetermined operating state. Discrimination method. 3. A method for determining an abnormality in a reference crank angle position detection system for an internal combustion engine according to claim 1, wherein the crank angle pulse is counted by a ring counter having a step number equal to the predetermined value.