JP4507201B2 - Control device for multi-cylinder internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a multi-cylinder internal combustion engine, and more particularly to a control device for a multi-cylinder internal combustion engine that can quickly identify a crank angle when the engine is started.

  Generally, the crank angle of a multi-cylinder internal combustion engine is detected by a crank angle sensor. That is, a timing rotor having a plurality of teeth formed at equiangular intervals is attached to the crankshaft, and a crank angle sensor arranged facing the timing rotor outputs a pulse signal every time the teeth pass. The control unit receives a pulse signal from the crank angle sensor and detects the progress of the crank angle corresponding to the tooth interval. On the other hand, in the timing rotor, one of 360 ° corresponding to the top dead center of the specific cylinder is missing. The camshaft is also provided with a timing rotor and a cam angle sensor, and the control unit causes the top dead center of one cylinder as a reference cylinder based on a signal output from the cam angle sensor and a missing tooth signal output from the crank angle sensor. Detect points. Further, the control unit detects the crank angle from 0 to 720 ° which is one cycle of the 4-stroke engine by counting the number of crank pulse signals from the top dead center of the reference cylinder as 0 ° crank angle, Cylinder discrimination is performed as to which cylinder is in which stroke (intake, compression, expansion, exhaust).

  Thus, in such a configuration, the crank angle cannot be specified and the cylinder cannot be determined until at least the missing teeth of the timing rotor of the crankshaft are detected. Therefore, the crankshaft may have to rotate about 360 ° before the crank angle is specified and the cylinder is identified. This is an obstacle when trying to shorten the start-up time of the engine. Particularly in recent years, control devices for internal combustion engines that control ignition timing, fuel injection amount, fuel injection timing, and the like based on in-cylinder information such as in-cylinder pressure are also known. Most of these control devices are based on crank angle control. Therefore, the delay in specifying the crank angle and the cylinder discrimination may greatly affect the performance.

  In order to identify the crank angle and determine the cylinder at an early stage, there are methods of increasing the number of missing teeth on the timing rotor of the crankshaft or detecting the crank angle continuously using a magnetoresistive element. The hardware configuration is changed, which increases the cost.

  On the other hand, Patent Document 1 discloses a method of specifying a crank angle at the time of engine start using a soft method. According to this method, when the engine is started, the increase rate of the in-cylinder pressure of the cylinder that is in the compression stroke immediately after the start of cranking is the timing at which the crank angle when cranking is started is slower than the compression bottom dead center. The smaller it is, the smaller it is. Therefore, by using this characteristic, the crank angle at the start of cranking is specified based on the increasing speed of the in-cylinder pressure of the compression cylinder.

JP 2005-120905 A

  However, according to the method described in Patent Document 1, since the crank angle at the start of cranking is specified based on the rising speed of the in-cylinder pressure of the compression cylinder, the rising speed of the in-cylinder pressure and the crank angle at the start of cranking are determined. Therefore, there is a possibility that the crank angle cannot be specified with sufficient accuracy.

  Therefore, an object of the present invention is to provide a control device for a multi-cylinder internal combustion engine that can quickly and accurately specify a crank angle when the engine is started.

  In order to achieve the above object, a control apparatus for a multi-cylinder internal combustion engine according to an aspect of the present invention includes an in-cylinder pressure sensor provided for each cylinder, a crank angle sensor that outputs a pulse signal at a predetermined crank angle interval, Based on the in-cylinder pressure detected by the in-cylinder pressure sensor, a discriminating means for discriminating a cylinder that is initially in a compression stroke after the start of starting, and the pulse signal is output from the crank angle sensor during the compression stroke of the cylinder. At two timings, the in-cylinder pressure detected by the in-cylinder pressure sensor is acquired, the in-cylinder pressure, a predetermined relationship established between the in-cylinder pressure and the in-cylinder volume during the compression stroke, and the two timings Based on the crank angle interval between them and the predetermined relationship established between the crank angle and the in-cylinder volume, the crank angle value of the earlier timing of the two timings is specified. Characterized in that a crank angle specifying means for.

  According to this aspect of the present invention, the value of the crank angle at the time of starting the engine can be quickly and accurately specified using a software method without significantly changing the existing hardware configuration. If the value of the crank angle is specified in this way, predetermined fuel injection control and ignition control can be executed, so that predetermined start control can be executed from the first compression stroke cylinder, and the engine start time is shortened. be able to. There are few values and relationships used for specifying the crank angle every time the engine is started, and the specified crank angle is determined at predetermined crank angle intervals at which a pulse signal is output from the crank angle sensor. Limited to crank angle. For this reason, it becomes possible to specify the crank angle with high accuracy and stably.

  The predetermined relationship established between the in-cylinder pressure and the in-cylinder volume during the compression stroke is preferably a relationship in which the product of the in-cylinder pressure and the value obtained by raising the in-cylinder volume to a power of a predetermined index is constant. .

That is, assuming that compression in the compression stroke is ideal adiabatic compression, a relationship of PV ^κ = (constant) (where κ is a predetermined index) between the in-cylinder pressure P and the in-cylinder volume V during the compression stroke. Is known to hold. Therefore, the crank angle can be specified with high accuracy by utilizing this relationship.

  Further, it is preferable that the crank angle specifying means specifies a crank angle value that makes the difference between the products at the two timings closest to zero as the crank angle value at the previous timing.

For the compression cylinder, if the cylinder pressure at the earlier timing of the two timings is P1, the cylinder volume is V1, the cylinder pressure at the later timing of the two timings is P2, and the cylinder volume is V2, P1 · ^V1κ = P2 · ^V2κ holds according to the relationship of ^PVκ = (constant). Therefore, the crank angle value that makes P1 · V1 ^κ −P2 · V2 ^κ closest to zero can be specified as the crank angle value at the previous timing.

  The crank angle interval between the two timings is preferably a multiple of the crank angle interval of the pulse signal output from the crank angle sensor.

  According to the present invention, it is possible to provide a control device for a multi-cylinder internal combustion engine that can quickly and accurately specify a crank angle when the engine is started.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  The control device for a multi-cylinder internal combustion engine in the present embodiment is different from a normal control device in that various control amounts (ignition timing, fuel injection amount, fuel injection) of the engine based on in-cylinder information detected by the in-cylinder information detection means. Control the timing etc. directly. That is, in a normal control device, the control amount that seems to be optimal for each operating state of the engine is obtained by an experiment in advance and mapped, and the engine is controlled by applying each map value during actual engine operation. Map control is generally performed. In contrast, the control device of the present embodiment directly detects the combustion state in the cylinder at the time of engine operation, and various control amounts so as to match the detected combustion state with a predetermined optimum combustion state. Is controlled. According to this method, it is possible to greatly simplify the creation of various maps, that is, the adaptation, which has conventionally required a lot of time and labor, and there is an advantage that the development period can be greatly shortened. .

  In-cylinder information representative of the in-cylinder combustion state is typically in-cylinder pressure, and the in-cylinder pressure sensor for detecting the in-cylinder pressure is also provided for each cylinder in the control device of this embodiment. The control amount to be controlled is typically combustion start timing (ignition timing for gasoline engines, ignition timing for diesel engines), fuel injection amount, fuel injection timing, and the like.

  FIG. 1 shows a control apparatus for a multi-cylinder internal combustion engine according to this embodiment. The internal combustion engine 1 generates power by burning a fuel / air mixture in a combustion chamber 3 formed in a cylinder block 2 and reciprocating a piston 4 in the combustion chamber 3. Although only one cylinder is shown in the figure, the internal combustion engine 1 is configured as a multi-cylinder engine, and in the case of the present embodiment, is configured as a 4-cylinder engine. The internal combustion engine 1 of the present embodiment is a spark ignition internal combustion engine, more specifically a gasoline engine.

  An intake port of each combustion chamber 3 is connected to an intake branch pipe 5 for each cylinder, and an exhaust port of each combustion chamber 3 is connected to an exhaust branch pipe 6 for each cylinder. The cylinder head of the internal combustion engine 1 is provided with an intake valve Vi for opening and closing the intake port and an exhaust valve Ve for opening and closing the exhaust port for each cylinder, that is, for each combustion chamber 3. Further, the internal combustion engine 1 has a spark plug 7 for each cylinder, and the spark plug 7 is disposed in the cylinder head so as to face the corresponding combustion chamber 3.

  A surge tank 8 as a collecting passage is connected to the upstream side of each intake branch pipe 5. An intake pipe L1 is connected to the upstream side of the surge tank 8, and the intake pipe L1 is connected to an air intake port (not shown) through an air cleaner 9. A throttle valve (in this embodiment, an electronically controlled throttle valve) 10 is disposed in the middle of the intake pipe L1 (between the surge tank 8 and the air cleaner 9). On the other hand, on the downstream side of the exhaust branch pipe 6, a front-stage catalyst device 11a including a three-way catalyst and a rear-stage catalyst device 11b including a NOx storage reduction catalyst are connected.

  Furthermore, the internal combustion engine 1 has an injector 12 for each cylinder, and the injector 12 is disposed in the intake branch pipe 5 so as to inject fuel into the intake port. The internal combustion engine 1 is not limited to such an intake passage (particularly intake port) injection type, and may be a direct injection type.

  Each of the spark plugs 7, the throttle valve 10 and the injectors 12 described above are electrically connected to an electronic control unit (hereinafter referred to as ECU) 20 as a control means. The ECU 20 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all not shown. Various sensors including the crank angle sensor 14 are electrically connected to the ECU 20 via an A / D converter or the like (not shown). The ECU 20 controls the spark plug 7, the throttle valve 10, the injector 12, and the like so as to obtain a desired output based on detection values of various sensors.

  The internal combustion engine 1 has an in-cylinder pressure sensor 15 including a semiconductor element, a piezoelectric element, an optical fiber detection element, or the like for each cylinder. Each in-cylinder pressure sensor 15 is disposed on the cylinder head so that the pressure receiving surface faces the corresponding combustion chamber 3, and is electrically connected to the ECU 20 via an A / D converter (not shown). Each in-cylinder pressure sensor 15 outputs a signal corresponding to the in-cylinder pressure in the corresponding combustion chamber 3 to the ECU 20. The in-cylinder pressure detected by the in-cylinder pressure sensor 15 is a relative pressure with respect to the atmospheric pressure. Further, the internal combustion engine 1 has an intake pressure sensor 16 that detects the pressure (intake pressure) of intake air in the surge tank 8 as an absolute pressure. The intake pressure sensor 16 is electrically connected to the ECU 20 via an A / D converter or the like (not shown), and gives a signal indicating the absolute pressure of the intake air in the surge tank 8 to the ECU 20. The detected values of the crank angle sensor 14, each in-cylinder pressure sensor 15 and the intake pressure sensor 16 are updated and stored in predetermined storage areas (buffers) of the ECU 20 by predetermined amounts every minute time.

  Here, the crank angle detection by the crank angle sensor 14 will be described. A rotor (timing rotor) 26 as shown in FIG. 2A is fixed to the crankshaft of the internal combustion engine 1. For example, 70 teeth 26a lacking only two teeth are formed at a predetermined angle Δθ (in this embodiment, Δθ = 5 °) and at equal angular intervals. A crank angle sensor 14 made of, for example, an electromagnetic pickup is disposed facing these teeth 26a. The crank angle sensor 14 outputs a pulse signal each time the teeth 26a of the rotor 26 pass through the crank angle sensor 14.

  That is, when the teeth 26a of the rotor 26 approach the crank angle sensor 14 and leave the crank angle sensor 14, the crank angle sensor 14 outputs an output voltage whose potentials are opposite to each other as indicated by X in FIG. (Sensor output) V is generated. This sensor output V is waveform-shaped by an AD converter with a constant voltage as a reference, and as a result, a pulse signal (crank pulse) which is a rectangular wave corresponding to the tooth 26b of the rotor 26 as indicated by Y in FIG. ) Is generated and input to the ECU 20. Thus, the ECU 20 can recognize the crank angle for each angle Δθ (= 5 °) from the input pulse signal.

  In the present embodiment, when the pulse signal shown in FIG. 4B rises, the reference time of the pulse signal is set. That is, the ECU 20 detects the progress of the crank angle Δθ at every moment when the pulse signal rises. The time when the pulse signal falls may be used as the reference time of the pulse signal.

  When the missing tooth portion 26b of the rotor 26 passes through the crank angle sensor 14, the interval between pulses increases as indicated by Z in FIG. From the signal corresponding to the missing tooth portion 26b and the signal of the cam angle sensor (none of which is shown) provided facing the timing rotor of the camshaft, the ECU 20 causes the top dead center of a predetermined reference cylinder. A point is detected, and further cylinder discrimination is performed. Further, the ECU 20 detects the crank angle of the internal combustion engine 1 by counting the number of crank pulses from the top dead center of the reference cylinder. The ECU 20 further calculates the engine speed NE by counting the number of crank pulses generated during a predetermined time.

  By the way, with this configuration alone, the crank angle value cannot be specified and the cylinder cannot be discriminated until at least the missing part 26b of the timing rotor of the crankshaft is detected. Accordingly, immediately after the start of the engine, until the crankshaft rotates about 360 ° in the longest case, the crank angle cannot be specified and the cylinder cannot be determined, and the fuel injection control and the ignition control based on the crank angle cannot be executed. . This is a problem in shortening the start time of the engine.

  Therefore, in order to solve this problem, the control device for a multi-cylinder internal combustion engine according to the present embodiment executes the following processing when starting the engine, and enables early crank angle specification and cylinder discrimination.

  Hereinafter, processing at the time of engine start in the present embodiment will be described. Here, the internal combustion engine of the present embodiment has four cylinders, and the first cylinder (# 1), the second cylinder (# 2), the third cylinder (# 3), and the fourth cylinder in order from one end side in the crankshaft direction. (# 4). Referring to FIG. 3, the ignition order or combustion order is the order as shown in the figure, that is, the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder. FIG. 3 shows each stroke (intake, compression, expansion, exhaust) of each cylinder as the crank angle progresses. Each stroke has a crank angle period of 180 °, and one cycle of the internal combustion engine in which all cylinders complete the entire stroke is a crank angle period of 720 °.

  FIG. 4 shows processing at the time of engine start executed in the present embodiment. FIG. 5 shows the state of the change in the cylinder pressure P of the cylinder that is initially in the compression stroke after the start of the engine (hereinafter referred to as the compression cylinder) and the generation state of the crank pulse Y. . First, the ignition switch is turned on by the driver (S101). At this time, cranking or starting of the internal combustion engine has not yet started, and only energization of the ECU 20 and the sensors is executed. Accordingly, the inside of the surge tank 8 is at the atmospheric pressure Pa, and the atmospheric pressure Pa is detected as an absolute pressure by the intake pressure sensor 16 and acquired by the ECU 20. This detected value Pa of atmospheric pressure is used later when correcting the detected value of in-cylinder pressure to an absolute pressure. After the acquisition of the atmospheric pressure Pa is thus completed, cranking, that is, starting of the internal combustion engine is started (S102). The crank angle at the time when the cranking is started is defined as θs.

  When starting of the internal combustion engine is started, the cylinder pressure P of each cylinder detected by the cylinder pressure sensor 15 of each cylinder is acquired by the ECU 20 at the timing when the crank pulse is output, and converted into absolute pressure. , Stored in the buffer of the ECU 20. The ECU 20 first acquires the detected values of the in-cylinder pressure of each cylinder at the timing (hereinafter referred to as “first timing”) θ1 when the crank pulse is first output after the engine start is started, and these detected values of the in-cylinder pressure. Is converted into an absolute pressure using the atmospheric pressure Pa acquired in S101, and then stored in the buffer as in-cylinder pressure P1 (i) of each cylinder (i means a cylinder number, i = 1, 2, 3, 4). (S103). Next, the ECU 20 determines a crank pulse output timing (hereinafter referred to as “crank pulse output timing”) that is delayed from the first timing θ1 by a crank angle interval α (α = 4Δθ = 20 ° CA in this embodiment) equal to a predetermined multiple of the crank angle interval Δθ. At θ5 (referred to as “second timing”), in-cylinder pressure detection values of each cylinder are acquired, and these in-cylinder pressure detection values are converted into absolute pressures using the atmospheric pressure Pa acquired in S101. The in-cylinder pressure P5 (i) is stored in the buffer (S104).

  Next, the ECU 20 uses the in-cylinder pressures P1 (i) and P5 (i) of these cylinders to determine the cylinder (compression cylinder) that is initially in the compression stroke after the start of the engine (S105). That is, as shown in FIG. 6, before the cranking is started (before θs), the in-cylinder pressures P (i) of all the cylinders are maintained at substantially the atmospheric pressure Pa. Next, when cranking is started (after θs), the in-cylinder pressure P (1) of the cylinder (first cylinder in the illustrated example) that was in the middle of the compression stroke gradually increases. On the other hand, the in-cylinder pressures P (2), P (3), and P (4) of the remaining cylinders (second cylinder, third cylinder, and fourth cylinder in the illustrated example) hardly change.

  Therefore, the ECU 20 determines the difference or change ΔP (i) (= P5) between the in-cylinder pressure P1 (i) of each cylinder at the first timing θ1 and the in-cylinder pressure P5 (i) of each cylinder at the second timing θ5. (I) −P1 (i)) is calculated, and a cylinder having the in-cylinder pressure change ΔP (i) having a positive value or the maximum value is determined to be a compression cylinder. By specifying the compression cylinder, the stroke state of each cylinder as shown in FIG. 3 is specified at the same time.

  Other methods for determining the compression cylinder are also conceivable. For example, the in-cylinder pressure P5 (i) of each cylinder at the second timing θ5 is simply compared with the atmospheric pressure Pa or a predetermined threshold value, and the cylinder having the atmospheric pressure Pa or higher than the predetermined threshold value is compressed. May be specified.

  Next, the ECU 20 uses the in-cylinder pressures P1 (1) and P5 (1) (hereinafter simply referred to as P1 and P5) acquired in S103 and 104 for the specified compression cylinder (referred to as the first cylinder for convenience), Predetermined arithmetic processing as described below is executed to specify the values of the crank angles θ1 and θ5 at the first and second timings (ie, how many are the crank angles θ1 and θ5) (S106). .

That is, if compression in the compression stroke is ideal adiabatic compression, a relationship of PV ^κ = (constant) is established between the in-cylinder pressure P (absolute pressure) and the in-cylinder volume V during the compression stroke. Is known. Here, κ is a predetermined index, for example, κ = 1.32. In other words, during the compression stroke, the product PV ^κ of the in-cylinder pressure P and the value V ^{κ obtained} by raising the in-cylinder volume V by the predetermined index ^κ is kept constant. Therefore, for the compression cylinder specified in S105, the following relationship is established when the cylinder volume at the first timing θ1 is V1 and the cylinder volume at the second timing θ5 is V5.
P1 · V1 ^κ = P5 · V5 ^κ (1)
Here, the following function G (θ) is considered.
G (θ) = P1 · V1 κ -P5 · V5 κ ··· (2)
In this case, if the values of the in-cylinder volumes V1, V5 such that G (θ) is zero, and thus the crank angle values corresponding to these in-cylinder volumes V1, V5, are obtained, the obtained crank angle value is obtained. This is the value of the crank angle at the first and second timings.

  Incidentally, there is a certain geometrically determined relationship between the crank angle θ and the in-cylinder volume V. In this embodiment, this relationship is shown in the ECU 20 as a map format (function format) as shown in FIG. It may be).

  Further, there is a crank angle interval of α (= 4Δθ = 20 °) between the crank angle θ1 corresponding to the cylinder volume V1 and the crank angle θ5 corresponding to the cylinder volume V5, and θ5 between the two. = Θ1 + α.

  FIG. 8 is a graph showing the relationship between the crank angle θ and the cylinder volume V in the map of FIG. As shown in the figure, in the compression stroke, the in-cylinder volume V tends to decrease as the crank angle θ increases. Referring to FIG. 8, the ECU 20 has two in-cylinder volumes V1 having a crank angle interval of α such that G (θ) is made to be closest to zero or almost zero from the map of FIG. , V5, and thus the two crank angles θ1, θ5 corresponding to the in-cylinder volumes V1, V5 are calculated or searched. Here, the calculated crank angles θ1 and θ5 are limited to crank angles at predetermined predetermined crank angle intervals Δθ at which pulse signals are output from the crank angle sensor 14.

  Thereafter, the ECU 20 specifies or confirms the crank angle θ1 of the earlier timing of the calculated two crank angles θ1 and θ5 as the value of the crank angle at the first timing (S107), and ends the process.

  FIG. 9 shows a general relationship between the crank angle θ at the first timing and the value of the function G (θ). As shown in FIG. 9, the crank angle θ at the first timing is compressed. The value of the function G (θ) tends to decrease as it approaches the top dead center (0 °). The crank angle at which G (θ) = 0 is the crank angle at the first timing to be specified.

  As described above, according to the present embodiment, it is possible to quickly and accurately specify the value of the crank angle at the time of starting the engine using a software method without significantly changing the existing hardware configuration. In particular, according to the present embodiment, the crank angle is specified at a very early stage of less than 25 ° CA after the engine start is started. If the crank angle is specified in this way, predetermined fuel injection control and ignition control based on the crank angle can be executed, and therefore, predetermined start control can be executed from the first compression stroke cylinder, and the engine start time is shortened. can do.

  In addition, the values and relational expressions used for specifying the crank angle according to the present embodiment have very few variations each time the engine is started, and the specified crank angle is determined in advance by outputting a pulse signal from the crank angle sensor. The crank angle is limited to a predetermined predetermined crank angle interval Δθ. For this reason, the crank angle which is a true value can be specified with high accuracy and stability.

  After the crank angle θ1 at the first timing is specified in this way, the subsequent crank angle can also be specified by counting the crank pulses, and therefore the top dead center is reached from the timing rotor of the crankshaft or camshaft. There is a possibility that a point detection location (such as a missing tooth portion) can be omitted. However, since such a top dead center detection location can directly and accurately detect the crank angle corresponding to the top dead center, the crank angle specified by the top dead center detection location is set as necessary. It may be used to correct the crank angle obtained from the processing.

  The crank angle interval α between the first timing θ1 and the second timing θ5 is a value that can obtain a sufficient in-cylinder pressure difference for accurate crank angle specification and can ignore the influence of sensor noise and the like. In addition, the value is preferably such that the crank angle can be identified quickly. From this point of view, in the present embodiment, the crank angle interval α between the first timing θ1 and the second timing θ5 is set to a multiple of the crank pulse interval Δθ, particularly four times. However, if the above-described object can be achieved, the crank angle interval α between the first timing θ1 and the second timing θ5 is made equal to the crank pulse interval Δθ (that is, to be equal to one time the crank pulse interval Δθ). It is also possible to In this case, the second timing is θ2 shown in FIG. 5, and the crank angle can be specified more quickly. Further, the crank angle interval α between the first and second timings is not limited to four times the crank pulse interval Δθ, and may be set to other multiple times such as three times or five times.

  The first and second timings (first and second timings) that are two timings may be arbitrary timings as long as both timings are in the compression stroke. The first timing is the timing at which the crank pulse is output first after the start of the engine in the above-described embodiment. However, the present invention is not limited to this, and at the timing at which a plurality of crank pulses are output after the start of the engine. There may be.

  According to the present embodiment, the cylinder discrimination is performed simultaneously with the acquisition of the in-cylinder pressure P5 (i) at the second timing θ5. Therefore, when the in-cylinder pressure values of the two compression cylinders are acquired after the cylinder discrimination is performed. In comparison with this, it is possible to shorten the time from the start of engine start until the crank angle is specified. However, an embodiment in which the in-cylinder pressure values at two points of the compression cylinder are acquired after performing cylinder discrimination is also possible. Further, referring to FIG. 5, the in-cylinder pressure detection in the cylinder discrimination may be performed at a timing (θ2, θ3, or θ4) before θ5.

  Various other embodiments of the present invention are conceivable. For example, a control device for an internal combustion engine that performs normal map control may be used. The number of cylinders is not limited to four and can be any number of cylinders. In the above embodiment, the cylinder pressure sensor that detects the relative pressure to the atmospheric pressure is used. However, the present invention is not limited to this, and a cylinder pressure sensor that detects the cylinder pressure as an absolute pressure may be used. In this case, it is not necessary to convert the detected in-cylinder pressure into an absolute pressure, and therefore the means for detecting the atmospheric pressure (the intake pressure sensor in the embodiment) can be omitted. In the above-described embodiment, the intake pressure sensor is also used as the atmospheric pressure detection sensor. However, a configuration in which a separate atmospheric pressure detection sensor is also possible.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

It is a schematic block diagram which shows the control apparatus of the internal combustion engine which concerns on embodiment of this invention. It is a figure regarding the detection of the crank angle by a crank angle sensor, (A) is the schematic of a crank angle sensor and a rotor, (B) is the signal output from a crank angle sensor, and the pulse obtained by shaping this Signal. It is a table | surface which shows each stroke state of each cylinder. It is a flowchart which shows the process at the time of engine starting in this embodiment. It is a graph which shows the change of the cylinder pressure in a compression cylinder, and the generation state of a crank pulse. It is a graph which shows the change of the cylinder pressure of each cylinder immediately after an engine start-up. The map into which the relationship between a crank angle and a cylinder internal volume was input is shown. It is a graph which shows the change of the cylinder volume accompanying the advance of a crank angle. It is a graph which shows the general relationship between the crank angle of the first timing and the value of the function G (θ).

Explanation of symbols

1 Internal combustion engine 14 Crank angle sensor 15 In-cylinder pressure sensor 16 Intake pressure sensor 20 Electronic control unit (ECU)
26 rotor 26a tooth 26b missing tooth portion θ1 first timing (previous timing)
θ5 Second timing (later timing)
P Cylinder pressure P1 Cylinder pressure P5 at the first timing Cylinder pressure V1 at the second timing Cylinder volume V5 at the first timing Cylinder volume α at the second timing Crank angle between the first and second timings Interval Δθ Crank angle interval κ between crank pulses Predetermined index G (θ) Function

Claims (4)

An in-cylinder pressure sensor provided for each cylinder;
A crank angle sensor that outputs a pulse signal at predetermined crank angle intervals;
Means for acquiring from the in-cylinder pressure sensor the in-cylinder pressure at the first timing and the second timing which are two timings at which the pulse signal is output from the crank angle sensor;
A discriminating means for discriminating a cylinder that is initially in a compression stroke after the start of the engine based on the in-cylinder pressure at the first timing and the in-cylinder pressure at the second timing ;
The cylinder pressure at the first timing and the second timing during the compression stroke of the cylinder, the predetermined relationship established between the cylinder pressure and the cylinder volume during the compression stroke, and the first timing Crank angle specifying means for specifying the crank angle value of the first timing based on the crank angle interval between the second timing and a predetermined relationship established between the crank angle and the cylinder volume ;
With
A control apparatus for a multi-cylinder internal combustion engine , wherein a crank angle interval between the first timing and the second timing is a multiple of the crank angle interval of the pulse signal .   The predetermined relationship established between the in-cylinder pressure and the in-cylinder volume during the compression stroke is a relationship that a product of the in-cylinder pressure and a value obtained by raising the in-cylinder volume by a predetermined index is constant. The control apparatus for a multi-cylinder internal combustion engine according to claim 1. The crank angle specifying means specifies a crank angle value that makes the difference between the products at the first timing and the second timing closest to zero as the crank angle value at the first timing. The control apparatus for a multi-cylinder internal combustion engine according to claim 2.   The control apparatus for a multi-cylinder internal combustion engine according to any one of claims 1 to 3, wherein the first timing is a timing at which a pulse signal is first output after engine start.

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