JP2010185311A - Engine control system and cam stem sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving the re-startability of an engine. <P>SOLUTION: The tooth of a cam stem sensor is formed at the outer peripheral surface of a rotor at a position 60° before a top dead center and near a crank angle. The crank position at an idle stop is such a position that a compression stroke is sufficiently secured in a cylinder which is discriminated. Fuel injection control according to the crank position can be performed by learning cylinder information so that fuel can be injected in the cylinder discriminated. By injecting the fuel into the discriminated cylinder by the fuel injection control, the fuel is burned in the explosion stroke, and the engine is re-started quickly. In other words, the fuel can be injected in the initial compression stroke after a cam signal is inputted. Consequently, the re-startability of the engine can be improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for improving engine restart performance.

  Due to environmental concerns and demands for fuel saving, the engine automatically stops when the vehicle is stopped, and the engine automatically restarts when the driver performs an operation intended to resume driving. Automobiles with a function (also called idling stop) have been put into practical use.

  In an automobile having such an idle stop function, the engine stop and start are inevitably repeated frequently. Therefore, it is possible for the driver to improve the startability when restarting the engine from the idle stop state (that is, to shorten the time until the engine starts after the driver performs an operation intended to resume running). In order not to give an unpleasant feeling, it is required more than a normal vehicle without an idle stop function.

  One factor that greatly affects the startability of such an engine is cylinder discrimination. The cylinder discrimination means that the rotational position (crank position) of the crankshaft in one cycle (720 ° CA) of the engine is specified. In order to perform this cylinder discrimination quickly, it is necessary to recognize the crank position when the engine is stopped.

  The crank position is recognized as follows. That is, the crank position is specified based on the signal output from the NE sensor (crankshaft sensor) or G sensor (camshaft sensor) according to the rotation of the crankshaft (see, for example, Patent Document 1), and the crank position is specified. If so, a value corresponding to the specified crank position is set in the crank counter. After that, by updating the crank counter value based on the signal from the crank sensor, the latest crank position is always grasped, and fuel injection and ignition are performed on the engine based on the crank counter value. To do. These points are the same as those of a normal vehicle that does not have an idle stop function.

  In order to improve the startability of the engine, the value of the crank counter (that is, the value of the crank counter when the engine is stopped) is continuously stored without being reset even during idling stop. .

Japanese Patent Laid-Open No. 06-307280

  However, even if cylinder discrimination is performed as described above, a sufficient compression stroke may not be ensured in the cylinder that has been discriminated depending on the crank position during idle stop. In such a case, even if fuel is injected into the cylinder identified as the cylinder, fuel combustion does not occur in the explosion stroke. Then, in order to restart the engine, it is necessary to wait for generation of output due to fuel combustion in the next cylinder, which causes a problem that the restartability of the engine is deteriorated.

  The present invention has been made in view of these problems, and an object thereof is to improve engine restart performance.

  An engine control system according to a first aspect of the present invention for solving the above-described problems is a rotor fixed to a crankshaft of a multi-cylinder engine mounted on a vehicle and having teeth formed on the outer periphery thereof at intervals of a predetermined angle. A crankshaft sensor provided opposite to the outer periphery of the rotor and comprising a signal output unit for detecting the teeth and outputting a pulse, and an engine that rotates at a ratio of 1/2 with respect to the rotation of the crankshaft The rotor is fixed to the cam shaft and teeth are formed on the outer periphery of the cam shaft at intervals of a predetermined angle, and the signal output unit is provided to face the outer periphery of the rotor and detects the teeth and outputs a pulse. And a cam signal output from the crankshaft sensor in response to rotation of the crankshaft, and a cam signal output from the camshaft sensor in response to rotation of the camshaft. An engine control system configured to perform fuel injection on each cylinder of the engine based on a cylinder discrimination result by the cylinder discrimination means. The teeth are formed at a position near the 60 ° crank angle before top dead center on the outer periphery of the rotor.

  According to the engine control system of the present invention configured as above, the teeth of the camshaft sensor are formed at a position near the 60 ° crank angle before the top dead center on the outer periphery of the rotor. This cylinder position is a position where a sufficient compression stroke is secured in the cylinder whose cylinder is determined. Then, for example, the cylinder information is set so that fuel can be injected in the cylinder that has been discriminated, such as by specifying the crank position when the idle stop is stopped by counting the number of pulses from the start of the engine to the input of the cam signal. It is possible to learn and perform fuel injection control according to the crank position.

  Then, by injecting fuel into the cylinder determined by the fuel injection control, fuel combustion occurs in the explosion stroke, and the engine is restarted quickly. In other words, fuel injection can be performed in the first compression stroke after the cam signal is input.

  Therefore, the restart performance of the engine can be improved.

  Further, as in claim 2, the multi-cylinder engine may be a four-cycle internal combustion engine type four-cylinder diesel engine.

  Further, as in claim 3 or claim 4, the present invention is applicable to a camshaft sensor.

It is a block diagram showing the structure of the engine control system of this embodiment. It is a time chart which shows the signal form of a crank signal and a cam signal. It is a flowchart showing an engine control process. It is explanatory drawing regarding the setting specification of G regular tooth of this embodiment, (a) is a case where G regular tooth is the conventional setting specification, (b) is a case where G regular tooth is near top dead center (TDC) ( 1), (c) when the G normal tooth is near TDC (2), (d) when the G normal tooth is on the BTDC side from the compression limit, and (e) is 60 ° before the top dead center. The case near the crank angle is shown.

  Hereinafter, an engine control system according to an embodiment to which the present invention is applied will be described with reference to the drawings. In addition, this invention is not limited to this embodiment, It is possible to implement in various aspects.

  The engine control system 100 of the present embodiment controls a four-cycle internal combustion engine type four-cylinder diesel engine mounted on a vehicle.

[1. Description of configuration of engine control system 100]
As shown in FIG. 1, the engine control system 100 of the present embodiment includes an engine control device 1, a crankshaft sensor 11, and a camshaft sensor 13.

  Among these, the engine control device 1 includes a microcomputer 3 and input circuits 5 and 7.

  In the engine control device 1, a rotation signal (crank signal) from a crankshaft sensor (NE sensor) 11 attached to the engine is input to the microcomputer 3 via the input circuit 5, and is also attached to the engine. A rotation signal (cam signal) for cylinder discrimination from the cam shaft sensor (G sensor) 13 is input to the microcomputer 3 via the input circuit 7.

  Here, the crankshaft sensor 11 is fixed to the crankshaft of the engine, and has a rotor 11a whose teeth are formed on the outer periphery at intervals of a predetermined angle (10 ° in the present embodiment), and opposed to the outer periphery of the rotor 11a. And an electromagnetic pickup type signal output unit 11b that detects the teeth and outputs a pulse. A single tooth missing portion A with two missing teeth is provided on the outer periphery of the rotor 11a.

  Therefore, the crank signal input to the microcomputer 3 from the crankshaft sensor 11 (specifically, its signal output unit 11b) via the input circuit 5 is low every time the crankshaft rotates 10 ° (every 10 ° CA). When the crank position changes to a pulse shape such as level → high level → low level and the crank position comes to a reference position where the tooth missing part A of the rotor 11a faces the signal output part 11b, the crank signal The rising edge interval becomes three times longer. Therefore, a rising edge as an effective edge occurs every 10 ° CA in the crank signal, and when the crank position comes to the reference position, a tooth missing portion A in which two rising edges are missing appears. In the following description, the high level crank signal is referred to as an NE pulse.

  On the other hand, the camshaft sensor 13 is fixed to the camshaft of the engine that rotates at a ratio of 1/2 with respect to the rotation of the crankshaft, and teeth are provided on the outer periphery thereof at intervals of a predetermined angle (90 ° in this embodiment). The formed rotor 13a and an electromagnetic pickup type signal output unit 13b that is provided opposite to the outer periphery of the rotor 13a and detects the teeth and outputs a pulse. In the present embodiment, the teeth of the camshaft sensor 13 (hereinafter referred to as G regular teeth) are formed in the outer periphery of the rotor 13a at a position near the 60 ° crank angle before top dead center. One extra tooth portion B provided with extra teeth is provided on the outer periphery of the rotor 13a. The position of this extra tooth is set in the tooth missing portion A of the crank signal.

  Therefore, the cam signal input to the microcomputer 3 from the cam shaft sensor 13 (specifically, its signal output unit 13b) via the input circuit 7 is low every time the cam shaft rotates 90 ° (every 180 ° CA). Even when the level changes from high level to low level and changes in a pulse shape, the rotational position of the camshaft reaches the reference position where the extra tooth B of the rotor 13a faces the signal output part 13b. , It changes in a pulse shape such as low level → high level → low level. Therefore, a rising edge as an effective edge is generated in the cam signal every 180 ° CA. Further, in the cam signal, when the rotational position of the cam shaft reaches the reference position, an extra tooth portion B consisting of one rising edge appears. In the following description, the high level cam signal is referred to as a G pulse.

  The crank signal and cam signal thus output are input to the microcomputer 3 of the engine control device 1. The microcomputer 3 calculates cylinder discrimination and crank angle (crank position) based on the input signal, and injection control such as fuel injection amount control, fuel injection timing control, and fuel pressure control based on the result of the calculation processing. Execute.

  Note that other configurations of the engine control device 1 are in accordance with known techniques, and thus detailed description thereof is omitted here.

[2. About setting of G regular tooth]
Next, the setting of the G regular tooth of the camshaft sensor 13 will be described.

  As described above, in this embodiment, the G regular tooth of the camshaft sensor 13 is formed at a position near the 60 ° crank angle before top dead center on the outer periphery of the rotor 13a. As a result, the cylinder at which the crank position at the time of idling stop is determined to be a position where a sufficient compression stroke is ensured. This is because of the following reasons (1) to (5).

  (1) That is, conventionally, the cam signal based on the G regular teeth is used for cylinder discrimination and diagnosis, but is not used for fuel injection control. Therefore, in the present invention, the cam signal based on the G regular teeth is used also at the time of restart after the idle stop stop. For this purpose, it is sufficient that the cylinder having the crank position can be discriminated when the idle stop is stopped (see FIG. 4A). This is because the cylinder discrimination result is used only for several fuel injections at the time of restart after idling stop stop, and thereafter shifts to normal control based on cylinder information obtained from missing tooth recognition.

  (2) Considering the reverse rotation of the crankshaft and the final crank stop position when the idle stop is stopped, the set position of the G regular tooth should be close to the top dead center (TDC) (FIG. 4 (b) )reference).

  (3) On the other hand, when the G normal tooth is set to a position close to the top dead center (TDC) as described above, the angle information is reset by the G normal tooth, so the fuel is used in the first compression stroke after the idle stop is stopped. Various calculations and various treatments for performing injection may not be in time (see FIG. 4C). Furthermore, if the G regular tooth is separated from the extra tooth (NE missing tooth position), it may be difficult to detect the extra tooth. Incidentally, when the extra tooth is not detected, various controls using the G pulse may not be executed.

  (4) If the G regular tooth is set to the top dead center (BTDC) side of the compression limit, depending on the stop position of the crankshaft, the fuel injection is performed even though combustion is possible in the first compression stroke. A situation not in time can occur (see FIG. 4D).

  (5) Further, it is not necessary to set the G regular tooth to the compression limit. If the G normal tooth is set to around 60 ° CA before top dead center (BTDC), the stop position is calculated by counting back the stop position by counting the number of NE pulses from when the engine is restarted until the cam signal is input. Whether it is before or after (see FIG. 4E).

  Due to the reasons listed in (1) to (5) above, when the G regular tooth of the camshaft sensor 13 is formed at a position near the 60 ° crank angle before top dead center on the outer periphery of the rotor 13a, idle stop The crank position at this time is a position where a sufficient compression stroke is secured in the cylinder whose cylinder is determined.

[3. Explanation of engine control processing]
Next, engine control processing executed by the microcomputer 3 included in the engine control apparatus 1 of the engine control system 100 will be described with reference to the timing chart of FIG. 2 and the flowchart of FIG.

  First, when an engine restart request is input, cylinder information indicating which cylinder the crank position is in is set (S105). The cylinder information is registered in association with each number of information such as the number of the cylinder having the crank position (cylinder number), the crank angle, the crank angle at the stop indicating the crank angle when the engine is stopped, and the angle counter.

  Subsequently, it is determined whether or not a G pulse by a G regular tooth is input (S110).

  In S110, when it is determined that the G pulse by the G regular tooth is not input (S110: NO), it is determined whether the NE pulse is input (S115). When it is determined that the NE pulse is not input (S115: NO), the process returns to S110 as it is to wait for the G pulse by the G normal tooth to be input. On the other hand, when it is determined that the NE pulse has been input (S115: YES), it is determined whether or not the input NE pulse is a pulse generated because the tooth missing part A is detected (S120).

  In S120, if the input NE pulse is not a pulse generated because the tooth missing part A is detected (S120: NO), the input NE pulse is a pulse generated because a normal tooth is detected. Then, 10 ° CA is added to the angle counter of the cylinder information (S130), and the process returns to S110. On the other hand, when the input NE pulse is a pulse generated because the tooth missing part A is detected (S120: YES), 30 ° CA is added to the angle counter of the cylinder information (S130), and the process returns to S110.

  On the other hand, in S110 described above, when it is determined that the G pulse by the G regular teeth has been input (S110: YES), 60 ° CA is added to the crank angle of the cylinder information and 60 ° CA is set to the crank angle at the time of stop. Add (S135). Then, the injection control (injection amount, injection timing, injection pattern, etc.) corresponding to the value of the crank angle at the time of stop of the cylinder information is set (S140). Further, it is determined whether or not the present time is the injection timing (S145).

  In S145, when it is not the injection timing at present (S145: NO), it is determined whether or not an NE pulse is input (S150). When the NE pulse is input (S150: YES), 10 ° CA is added to the crank angle of the cylinder information, and 60 ° CA is added to the crank angle at the time of stop (S155), and the process returns to S145. On the other hand, when the NE pulse is not input (S150: NO), the process returns to S145 as it is.

  In S145, if it is currently the injection timing (S145: YES), the injection control is executed based on the content set in S140 (S160).

[4. Effects of the embodiment]
Thus, according to the engine control system 100 of the present embodiment, the G regular tooth of the camshaft sensor 13 is formed at a position near the 60 ° crank angle before top dead center on the outer periphery of the rotor.

  For this reason, for the reasons listed in the above (1) to (5), the crank position at the time of idling stop is a position where a sufficient compression stroke is secured in the cylinder. Then, for example, the cylinder information is set so that fuel can be injected in the cylinder that has been discriminated, such as by specifying the crank position when the idle stop is stopped by counting the number of pulses from the start of the engine to the input of the cam signal. It is possible to learn and perform fuel injection control according to the crank position.

  Then, by injecting fuel into the cylinder determined by the fuel injection control, fuel combustion occurs in the explosion stroke, and the engine is restarted quickly. In other words, fuel injection can be performed in the first compression stroke after the cam signal is input.

  Therefore, the restart performance of the engine can be improved.

  In this embodiment, the present invention is applied to a four-cycle internal combustion engine type four-cylinder diesel engine. However, the present invention is applicable to other multi-cylinder engines.

DESCRIPTION OF SYMBOLS 1 ... Engine control apparatus, 3 ... Microcomputer, 5, 7 ... Input circuit, 11 ... Crankshaft sensor, 11a, 13a ... Rotor, 11b, 13b ... Signal output part, 13 ... Cam shaft sensor, 100 ... Engine control system

Claims (4)

A rotor that is fixed to a crankshaft of a multi-cylinder engine mounted on a vehicle and has teeth formed on the outer periphery thereof at intervals of a predetermined angle, and is provided to face the outer periphery of the rotor. A crankshaft sensor comprising a signal output unit for outputting
A rotor that is fixed to an engine camshaft that rotates at a ratio of 1/2 to the rotation of the crankshaft and that has teeth formed at intervals of a predetermined angle on the outer periphery thereof, and is provided opposite the outer periphery of the rotor A camshaft sensor comprising a signal output unit that detects the teeth and outputs a pulse;
Cylinder discrimination means for performing cylinder discrimination based on a crank signal output from the crankshaft sensor according to the rotation of the crankshaft and a cam signal output from the camshaft sensor according to the rotation of the camshaft. When,
An engine control system configured to perform fuel injection for each cylinder of the engine based on a cylinder discrimination result by the cylinder discrimination means,
The engine control system according to claim 1, wherein the teeth of the camshaft sensor are formed at a position near a 60 ° crank angle before top dead center on the outer periphery of the rotor.   The engine control system according to claim 1, wherein the multi-cylinder engine is a four-cycle internal combustion engine type four-cylinder diesel engine. A rotor that is fixed to a crankshaft of a multi-cylinder engine mounted on a vehicle and has teeth formed on the outer periphery thereof at intervals of a predetermined angle, and is provided to face the outer periphery of the rotor. Is fixed to a camshaft of the engine that rotates at a ratio of 1/2 with respect to the rotation of the crankshaft, and teeth are formed on the outer periphery at intervals of a predetermined angle. A camshaft sensor that is provided opposite to the outer periphery of the rotor and that includes a signal output unit that detects the teeth and outputs a pulse, and the crankshaft sensor according to the rotation of the crankshaft. Cylinder determining means for performing cylinder determination based on an output crank signal and a cam signal output from the cam shaft sensor in response to rotation of the cam shaft, and a cylinder by the cylinder determining means In camshaft sensor used in the engine control system configured to implement the fuel injection for each cylinder of the engine based on different result,
The cam shaft sensor is characterized in that the teeth of the cam shaft sensor are formed at a position near the 60 ° crank angle before top dead center on the outer periphery of the rotor.   The camshaft sensor according to claim 3, wherein the multi-cylinder engine is a four-cycle internal combustion engine type four-cylinder diesel engine.