JP6070983B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device that controls an internal combustion engine.

  In a four-stroke internal combustion engine having a plurality of cylinders, it is necessary to know which stroke each cylinder is currently in and to perform fuel injection control and ignition control.

  The crankshaft of the internal combustion engine is provided with a crank angle sensor for detecting the rotation angle and the engine speed. The crank angle sensor senses the rotation of the rotor fixed to the crankshaft, for example, every 10 ° CA (crank angle).

  Cam angle sensors are also attached to camshafts that open and close the intake valves or exhaust valves of each cylinder. The cam angle sensor senses the rotation of the rotor fixed to the camshaft, for example, at an angle obtained by dividing one rotation by the number of cylinders, for every 120 ° for a three-cylinder engine (240 ° CA if converted to a crank angle). To do.

  An ECU (Electronic Control Unit) that controls the operation of the internal combustion engine receives a crank angle signal and a cam angle signal, refers to both signals to grasp the stroke of each cylinder, and determines the fuel injection timing and ignition timing in the cylinder. (See Patent Document 1 below).

  By the way, although it is extremely rare, the transmission path between the crank angle sensor and the ECU may be disconnected, or the sensor itself may break down and the ECU may not be able to receive the crank angle signal. As a fail-safe in such a case, the ECU has a function of maintaining the operation of the internal combustion engine based on only the cam angle signal (see Patent Document 2 below).

JP 2005-207394 A JP 2001-234895 A

  Noise sometimes gets on the signal line where the ECU receives the cam angle signal. In a situation where the crank angle signal can be received, it is relatively easy to determine whether the pulse received via the cam angle signal line is a normal cam angle signal or noise. However, when the crank angle signal is absent, there is a high possibility that it may be mistaken as a regular cam angle signal even if it is noise received at a timing that would otherwise be impossible.

  An object of the present invention is to enable accurate discrimination between a regular cam angle signal and noise.

In the present invention, a crank angle signal output from a crank angle sensor that detects a rotation angle of the crankshaft in a predetermined angle unit, and a cam angle signal output from the cam angle sensor at least once during one rotation of the camshaft. When the crank angle signal cannot be received in the control device for controlling the internal combustion engine with reference to the above, the current signal received via the cam angle signal line and the previous regular cam angle signal received via the same line And the elapsed time between the previous regular cam angle signal received via the same line and the previous regular cam angle signal, and the former elapsed time and the latter Is compared with the judgment value set according to the engine speed estimated based on the regular cam angle signal sequence. In the mask period that starts immediately after receiving the signal via the cam angle signal line, the signal is compared with the mask threshold, and the signal is The control apparatus for an internal combustion engine is characterized in that the signal is ignored when the magnitude of the engine is less than the mask threshold, and the length of the mask period is longer when the rotational speed of the internal combustion engine is low. did.

  According to the present invention, it is possible to accurately discriminate between a regular cam angle signal and noise.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. The figure explaining the content of the discrimination process of the cam angle signal which the control apparatus of the internal combustion engine of the embodiment performs. The figure explaining the content of the noise removal process of the cam angle signal which the control apparatus of the internal combustion engine of the embodiment performs.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  The ECU 0 as the control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake that is output from a sensor that detects the amount of depression of the brake pedal Stepping amount signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake pressure in intake passage 3 (especially surge tank 33), water temperature sensor for detecting engine cooling water temperature Output from the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f output from the intake camshaft or exhaust camshaft. A cam angle signal (G signal) g is a sensor for to know the range of the shift lever (or, a shift position switch) shift range signal h or the like to be output from is input.

  From the output interface, an ignition signal i is output to the igniter of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k corresponding to the operation parameters via the output interface.

  It supplements regarding the cam angle signal g. The cam angle sensor senses the rotation angle of a rotor that is fixed to the camshaft and rotates integrally with the camshaft. The rotor is formed with teeth or protrusions for each angle obtained by dividing one rotation of the camshaft by the number of cylinders. In the case of a three-cylinder engine, teeth or protrusions are arranged every 120 ° (240 ° CA in terms of crank angle). The cam angle sensor faces the outer periphery of the rotor, detects that individual teeth or protrusions pass near the sensor, and transmits a pulse signal as the cam angle signal g each time. The ECU 0 is connected to a cam angle sensor via a cam angle signal line, and receives a pulse as a cam angle signal g through the cam angle signal line.

  The cam angle signal g is a signal indicating that any one of the cylinders 1 has reached a predetermined stroke. For example, a cam angle sensor is attached to the intake camshaft, and the signal g output from the cam angle sensor indicates the start of the intake stroke in each cylinder 1. In addition, in an internal combustion engine with a so-called phase change type variable valve timing mechanism, the cam angle signal g also represents a valve timing adjusted by the mechanism.

  Normally, the ECU 0 knows the current stroke of each cylinder 1 by referring to both the crank angle signal b and the cam angle signal g, and injects fuel at an appropriate fuel injection timing in each cylinder 1. The mixture is ignited at a proper ignition timing.

  However, when the ECU 0 cannot receive the crank angle signal b, it is necessary to know the current stroke of each cylinder 1 only by the cam angle signal g and determine the fuel injection timing and the ignition timing. At that time, it is extremely important to accurately determine whether the pulse signal received via the cam angle signal line is the normal cam angle signal g or noise.

FIG. 2 is a diagram for explaining a method for discriminating between the cam angle signal g and noise, which is executed by the ECU 0 of the present embodiment. In determining whether the signal G _i received via the cam angle signal line is the normal cam angle signal g or noise, the ECU 0 receives the current signal G _i and the cam angle signal line. An elapsed time T _i is measured between the cam angle signal G _i−1 and the previous cam angle signal G _i−1 determined to be a regular cam angle signal. In addition, the ECU 0 makes a progress between the previous cam angle signal G _i-1 and the previous cam angle signal G _i-2 received through the cam angle signal line and determined to be a normal cam angle signal. Time T _i-1 is measured.

Then, the ECU 0 calculates the ratio T _i / T _i-1 of both elapsed times, and compares this ratio T _i / T _i-1 with the determination value. If the ratio T _i / T _i-1 is larger than the determination value, it is determined that the signal G _i received this time is a normal cam angle signal. On the contrary, if the ratio T _i / T _i-1 is equal to or smaller than the determination value, it is determined that the signal G _i received this time is not a regular cam angle signal but noise.

The determination value is set according to the current rotational speed of the internal combustion engine (the crankshaft or camshaft). The determination value is larger as the engine rotational speed is lower (slower) and smaller as it is higher (faster). The ECU refers to at least the elapsed time T _i-1 between the previous regular cam angle signal G _i-1 and the last regular cam angle signal G _i-2 to determine the current engine speed. Infer. Then, a determination value corresponding to the estimated rotation speed is obtained and compared with the ratio T _i / T _i−1 . For example, map data defining the relationship between the engine rotational speed and the judgment value is stored in advance in the memory of the ECU 0, and the map is searched using the estimated rotational speed as a key, whereby the ratio T _i / T Know the decision value to compare with _i-1 .

According to the estimation of the current engine speed, the elapsed time T _i-2 between the previous regular cam angle signal G _i-2 and the previous regular cam angle signal G _i-3, and the past The elapsed time between the regular cam angle signals g may be referred to. In this case, the current rotational speed can be estimated in consideration of the acceleration tendency or the deceleration tendency of the engine rotational speed.

When it is determined that the signal G _i is noise, in order to determine whether the next signal G _{i + 1} received via the cam angle signal line is a normal cam angle signal g or noise. In this case, an elapsed time T _{i + 1} between the current signal G _{i + 1} and the previous regular cam angle signal G _i-1 is measured, and this elapsed time T _{i + 1} and the previous elapsed time T _i are measured. A ratio T _{i + 1} / T _i-1 to _-1 is calculated. Therefore, this ratio T _{i + 1} / T _i-1 is compared with a judgment value according to the estimated level of the engine speed. If the ratio T _{i + 1} / T _i-1 is larger than the determination value, the signal G _{i + 1} is a normal cam angle signal. If the ratio T _{i + 1} / T _i-1 is less than the determination value, it is determined that the signal G _{i + 1} is noise.

Incidentally, the above determination value is also the length of the mask period for removing noise from the signal received via the cam angle signal line. FIG. 3 is a diagram for explaining a mask processing technique for removing noise superimposed on the cam angle signal g, which is executed by the ECU 0. In FIG. 3, the solid line is the waveform of the regular cam angle signal g. The broken line represents the transition of the mask threshold when the engine rotational speed is relatively high, and the chain line represents the transition of the mask threshold when the engine rotational speed is relatively low. The ECU ₀ starts noise masking immediately after the timing t _{0 when} it is assumed that the pulse of the regular cam angle signal g is received. That is, when the magnitude of the signal received via the cam angle signal line is less than the mask threshold, only the regular cam angle signal g is extracted by ignoring the signal as noise.

The mask threshold gradually decreases as time elapses from the reference timing t ₀ and finally becomes 0. As shown in FIG. 3, the value of the mask threshold when the engine speed is low is smaller at the reference timing t ₀ than when the engine speed is high. On the other hand, the decay rate of the mask threshold is slower when the engine speed is low. Therefore, the mask period, that is, the period from the reference timing t ₀ until the mask threshold becomes 0 is also longer when the engine speed is low.

In this embodiment, the crank angle signal b output from the crank angle sensor that detects the rotation angle of the crankshaft in a predetermined angle unit, and the cam angle output from the cam angle sensor at least once during one rotation of the camshaft. In the control device 0 that controls the internal combustion engine with reference to the signal g, when the crank angle signal b cannot be received, the current signal Gi received through the cam angle signal line and the signal G _i received through the same line are received. The elapsed time T _i between the previous regular cam angle signal G _i-1 is obtained, and the previous regular cam angle signal G _i-1 received via the same line and the previous regular cam angle signal G _i-1 are obtained. An elapsed time T _i-1 between the signal G _i-2 and a ratio T _i / T _i-1 between the former elapsed time T _i and the latter elapsed time T _i-1 is obtained as a normal cam angle. It is set according to the engine speed estimated from the signal g sequence. By comparing the value, to constitute a control apparatus 0 for an internal combustion engine, wherein a current signal G _i is determined whether the noise is a normal cam angle signal g.

  According to the present embodiment, even when the crank angle signal b is absent, it is possible to accurately discriminate between the regular cam angle signal g and noise. As a result, the fail-safe reliability in a situation where the crank angle signal b cannot be received increases.

  The present invention is not limited to the embodiment described in detail above. Various modifications can be made to the specific configuration of each part, processing procedure, and the like without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
b ... Crank angle signal g ... Cam angle signal

Claims (1)

Referring to the crank angle signal output from the crank angle sensor that detects the rotation angle of the crankshaft in predetermined angle units, and the cam angle signal output from the cam angle sensor at least once during one rotation of the camshaft. In a control device for controlling an internal combustion engine,
If the crank angle signal cannot be received,
Find the elapsed time between the current signal received via the cam angle signal line and the previous regular cam angle signal received via the line,
In addition, the elapsed time between the previous regular cam angle signal received via the same line and the previous regular cam angle signal is obtained,
By comparing the ratio of the former elapsed time and the latter elapsed time with a judgment value set according to the engine rotational speed estimated based on the normal cam angle signal sequence, the current signal is It is to determine whether it is a regular cam angle signal or noise,
Also, in the mask period that starts immediately after receiving a signal via the cam angle signal line, the signal is compared with the mask threshold, and if the magnitude of the signal is less than the mask threshold, the signal is A control apparatus for an internal combustion engine, characterized in that it is ignored and the length of the mask period is longer when the rotational speed of the internal combustion engine is lower .

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