JP4493352B2 - Control method for internal combustion engine - Google Patents

Description

  The present invention relates to a control method for controlling starting by detecting a crank angle of an internal combustion engine of an automobile.

Conventionally, control synchronized with engine rotation, such as fuel and ignition of an internal combustion engine, is performed by measuring a rotating angle by a rotation sensor such as a magnetic pickup or a plate having a concavo-convex protrusion at a predetermined angle attached to a crankshaft or a camshaft, It controls cylinder discrimination and injection and ignition timing (see, for example, Patent Document 1).
JP 2002-227708 A

  However, this method has a problem that if the internal combustion engine does not rotate due to cranking, no pulse is generated, fuel and ignition cannot be controlled until the cylinder can be discriminated, and the starting time becomes long. As a result, there is also a problem that the cost increases due to the durability of the starter. There is also a method of injecting fuel immediately after starting all cylinders in order to shorten the starting time as much as possible, but in order to prevent backfire etc., the ignition signal must be after cylinder determination, Has the problem that the fuel is discharged as it is, and the exhaust is deteriorated.

  Therefore, an object of the present invention is to provide an internal combustion engine that can be surely performed with a short starting time and that does not deteriorate exhaust gas.

The method for controlling an internal combustion engine of the present invention according to claim 1, which has been made to solve the above-described problem, is a control method for an internal combustion engine having a control means for controlling an operating state of the internal combustion engine in accordance with a crank angle.
A crank angle detecting means for measuring at least a crank angle or a portion having a correlation with the crank angle when the internal combustion engine is stopped;
Cylinder operating process discriminating means for discriminating the operating process of each cylinder from the measured angle ;
The crank angle detecting means is made of a possible angle signal output means outputs at least two systems or more signal phases different output for angles,
In addition to the angle signal output means, a reference pulse generating means for generating a pulse at a specific angle portion according to rotation is provided.
The angle signal output means detects a rotation angle of a camshaft interlocked with an intake valve and an exhaust valve of an internal combustion engine, and the reference pulse generation means detects an angle of a crankshaft;
The angle signal output means is corrected by the angle measured by the reference pulse generating means,
The operating state at the start of the internal combustion engine is determined based on the process determined by the cylinder operation process determining means.

According to a second aspect of the present invention, there is provided a control method for an internal combustion engine according to the first aspect, wherein the angle signal output means includes two systems whose outputs with respect to the angle are out of phase at an angle of 90 °. And an angle is calculated from the output values of the two systems .

A method for controlling an internal combustion engine according to a third aspect of the present invention is the method for controlling an internal combustion engine according to the first or second aspect, wherein, when the internal combustion engine injects fuel into the intake port, it is at least in an exhaust process. And fuel injection to the vicinity of the port is performed on the cylinder determined by the cylinder operation process determining means .

A control method for an internal combustion engine according to a fourth aspect of the present invention is the control method for an internal combustion engine according to the first aspect, wherein the crank angle is normalized by performing upper and lower limits on the signal input from the angle signal output means. It is characterized by calculating .

  According to the present invention, the cam angle is determined before starting, fuel is supplied in advance to a cylinder that can be ignited next, and the supplied cylinder is immediately ignited at the start of rotation, so that startability is improved. There is an effect. Further, since the fuel is injected only into the necessary cylinders, there is an effect that the exhaust does not deteriorate. Further, the cam signal is normalized by the upper and lower limits, and the cam angle θ is corrected by the crank signal, so that the control accuracy is improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system configuration diagram of an internal combustion engine (engine) according to an embodiment.

  In the figure, reference numeral 1 is an air flow sensor for measuring the amount of air sucked into the internal combustion engine, 2 is a throttle valve for adjusting the amount of air sucked into the internal combustion engine in response to a passenger's request, and 3 is supplied to the engine An injector for injecting fuel, 4 an ignition coil for igniting the fuel in the cylinder, 5 an oxygen concentration sensor for measuring the exhaust gas oxygen concentration, and 6 generating a pulse (crank signal) corresponding to the rotation of the crankshaft Crank rotation sensor (reference pulse generating means) 7 is a cam angle for measuring the angle of a camshaft connected to a cam rotating at half the rotational speed by operating the opening and closing of the intake valve and the exhaust valve to synchronize with the crankshaft. It is a sensor (crank angle detection means). Here, one rotation of the camshaft is two rotations of the crankshaft, and if the cam angle is known, the crank angle is determined. Reference numeral 8 denotes an input of signals from the air flow sensor 1, oxygen concentration sensor 5, crank rotation sensor 6, and cam angle sensor 7. Control unit.

  Next, the structure of the crank rotation sensor will be described with reference to the simplified schematic diagram of FIG. Reference numeral 10 denotes a crankshaft plate which communicates with the crankshaft and has a protrusion at an angle to be generated, and 9 is a rotary pulse pickup which generates a pulse when the protrusion passes. As the rotary pulse pickup 9, a magnetic pickup constituted by a simple coil, a Hall element, or the like may be used. The position of the protrusion may be set to an angle that is convenient for controlling the fuel injection timing for each cylinder, one that controls the ignition timing, and an angle that is convenient for correcting the cam angle described later. . Either or both of the cam angle corrections may be used without being separated from the fuel and ignition signals. The example of FIG. 2 shows a 4-cylinder pattern which will be described later. Here, TDC represents the cylinder top dead center between the compression process and the explosion process of each cylinder.

  Next, the structure of the cam angle sensor 7 will be described with reference to the schematic diagram of FIG. Reference numeral 12 denotes a camshaft plate which is communicated with the camshaft and is divided and magnetized into N and S poles. 11 is a magnetic flux detection sensor (angle signal output means) which detects the direction of the magnetic flux and detects the angle of the camshaft plate It is. If the magnetic flux detection sensor 11 is a circuit as shown in FIG. 4 using a GMR that is a magnetoresistive element, two outputs (cam signals 1 and 2) shifted by 90 ° as an angular phase can be obtained. Reference numerals 14a, 14b, 15a, and 15b in FIG. 4 are GMR elements, which form a bridge circuit. 14a and 14b and 15a and 15b are 180 degrees out of phase, and 14a, 14b and 15a and 15b are 90 degrees out of phase. Further, the magnetic flux detection sensor 11 may be configured such that the same cam signals 1 and 2 can be obtained even if the two Hall sensors 13a and 13b are disposed at positions shifted by 90 ° as shown in FIG. Good. The output of the magnetoresistive element configured as described above is a trigonometric function output of one cycle with one rotation of the furniture. Therefore, the relationship between the two systems whose phases are shifted by 90 ° is a relationship between sine and cosine, and the angle can be calculated from the two outputs. As described above, the configuration using the magnetic flux detection sensor 11 and the camshaft plate 12 has a feature that an output can be obtained even when the engine is stopped.

  Next, the relationship between the cam signal and the engine operating state will be described with reference to FIG. FIG. 6 is an example of a four-cylinder four-cycle engine. The explosion order in this example is one cylinder, three cylinders, four cylinders, and two cylinders. When the three-cylinder TDC is a cam angle (θ) = 0, the value of the cam signal 1 is sin (θ + 45 °) and the value of the cam signal 2 is cos (θ + 45 °). Accordingly, the exhaust process for one cylinder is θ = 0 to 90 °, the intake process is θ = 90 ° to 180 °, the compression process is θ = 180 ° to 270 °, and the explosion process is θ = 270 ° to 0 °. On the other hand, the reference pulse signal, which is a crank signal, is configured to generate pulses of −70 ° (referred to as BTDC 70 °) and −110 ° (referred to as BTDC 110 °) from the TDC of each cylinder. For example, the BTDC 70 ° signal (θ = 290 °) for the three cylinders is used as a reference signal for determining the ignition timing of the three cylinders, and the BTDC 110 ° signal (θ = 250 °) determines the cylinder injection amount and the injection timing according to the operating state. Used as a reference signal. Since the optimum point differs depending on the engine, it may be set for each.

  Next, the overall control of fuel injection and ignition processing according to the present invention will be described with reference to the flowchart of FIG. The flow of FIG. 7 is calculated and controlled by a control unit 8 including a ROM, a RAM, and a CPU. In step 70, two signals (C1R, C2R) of the cam angle sensor 7 are first captured. In step 71, the captured C1R and C2R are normalized. Details of the normalization process will be described with reference to the flowchart of FIG. FIG. 8 shows the processing flow of C1R, and normalization processing may be performed for C2R as in this flow. In step 80, it is determined whether C1R is larger than C1MAX. If larger, C1MAX is updated to C1R in step 81. In step 82, it is determined whether C1R is smaller than C1MIN. If it is smaller, C1MIN is updated to C1R in step 83. Here, C1MAX and C1MIN are stored in a non-volatile memory. As an initial value, when the engine is assembled, the maximum output value of C1R is actually set to C1MAX and the minimum value of C1R is set to C1MIN to adjust the cam angle sensor 7. Operate and memorize. Alternatively, the average value may be used as an initial value and used when C1MAX and C1MIN are not set. In this way, by constantly updating the upper and lower limits, a value shift due to deterioration with time can be corrected, and a highly accurate output can always be obtained. In step 84, the cam signal 1 normalized by the values of CNMAX and CNMIN which are the upper and lower limits when normalized with the upper and lower limits of the input value C1MAX and C2MIN is calculated.

  In step 72 (cylinder operation process determination means) in FIG. 7, the determination of the operation process for each cylinder and the cam angle θr are obtained from the cam signals 1 and 2. The injection region determination will be described with reference to FIG. 9 taking a four-cylinder engine as an example. In step 90, it is determined whether the cam signal 1 is equal to or greater than UP45 (UP45: see FIG. 6) corresponding to sin (45 °). If true, the cam angle θr is obtained in step 91. Here, the cam angle θr is obtained by substituting the cam signal 2 into the function fB () in FIG. In step 92, it is determined whether the cam signal 2 is equal to or less than DW45 (DW45: see FIG. 6) corresponding to sin (−45 °). If true, the cam signal 1 is substituted into the function fB () in step 93, and The cam angle θr is obtained by adding °. In step 94, it is determined whether the cam signal 1 is DW45 or less. If true, the cam signal 2 is substituted into the function fA () in step 95, and 180 ° is added to obtain the cam angle θr. In step 96, the cam signal 1 is substituted into the function fA () and 270 ° is added to obtain the cam angle θr. Next, at step 97, the cam angle correction value θh based on the crank signal is subtracted to obtain the final cam angle θ. The cam angle correction value θh will be described later in the crank signal processing unit in step 73 of FIG. The process of each cylinder in FIG. 6 is determined based on the cam angle θ obtained here. Further, the cylinder in the process in which the engine starts rotating and can first take in the fuel is determined by the functions f1 (θ) to f4 (θ) in step 98. Reference numerals f1 (θ) to f4 (θ) denote stop-time fuel injection region determination areas of the respective cylinders shown in FIG. As the ignition timing is performed between the compression process and the explosion process, if fuel is injected before and after the exhaust process, the fuel can be sucked into the cylinder, compressed and ignited, and can be exploded in the shortest possible time. Start-up time can be shortened.

  The function fA () is an inverse trigonometric function of the sine function in the angle range of −45 ° to 45 °, and the function fB () is an inverse trigonometric function of the sine function at the angle of 135 ° to 225 °. Since the function fB () is equivalent to substituting the input as CNMAX−cam signal + CNMIN into the function fA (), the function fB () may be calculated using only the function fA ().

  Since the signals C1R and C2R of the cam angle sensor 7 are output even when the engine is stopped, the current cam angle θ and the process of each cylinder can be determined at the start time by the flow of FIG.

  Next, the crank signal processing at step 73 in FIG. 7 will be described. Here, based on the cam angle θ obtained in step 72, when the engine is rotated by a starter or the like, the next crank signal is determined and the cam angle correction value θh is obtained. The relationship between the crank signal and the cam angle in this embodiment is summarized in Table 1.

  In Table 1, the crank signal for a cam angle of 20 ° is BTDC 70 ° for four cylinders. This signal is a reference signal for ignition to the four cylinders. Similarly, the determined cam angles correspond to BTDC 70 ° and 110 ° for each cylinder.

  Next, specific crank signal processing will be described with reference to the flowchart of FIG. In step 100, it is determined whether the engine is stopped or immediately after the ignition switch (IGN SW) is turned on. If true, in step 101, the next crank signal when the engine is rotated by the cam angle θ is obtained. Predict. Thereafter, the crank signal is generated in the order of the cam angle θ in Table 1. Next, in step 102, it is determined whether there is a crank signal. Thereafter, the BTDC 110 ° signal of each cylinder is detected from the crank signal, and compared with the cam angle θr normalized around the area shown in FIG. 12, the deviation is stored. FIG. 12 shows the relationship between the crank signal of BTDC 110 ° and the cam angle θ. Here, the area between the BTDC 110 ° signal for two cylinders and the BTDC 110 ° for one cylinder is defined as area I, and each area is defined as shown in FIG. Area IV is an area where the cam angle θ exceeds 360 ° and becomes 0 °. FIG. 12 also shows the deviation between the cam angle θr (measured θ) measured for each BTDC 110 ° and the cam angle (actual θ) from the crank signal. This is a characteristic shift due to output distortion of the cam angle sensor 7 or the like. Next, the flow for obtaining the deviation will be described from step 103 to step 112 in FIG. In step 103, it is determined whether or not a BTDC 110 ° signal for one cylinder has been received. In step 105, it is determined whether or not a BTDC 110 ° signal for two cylinders has been received. In step 107, it is determined whether or not a BTDC 110 ° signal for three cylinders has been received. In step 109, it is determined whether or not a 4-cylinder BTDC 110 ° signal has been received. In step 111, it is determined whether the cam angle θr is smaller than 180 °, and if it is smaller, an offset of 360 is added to dθ4 in step 112. Finally, in step 113, the cam angle correction value θh is obtained. Here, dY1, dY2, and θX in the equation are determined as shown in Table 2 depending on the area of the cam angle θr.

  Next, the fuel injection process in step 74 of FIG. 7 will be described with reference to the flowchart of FIG. In step 130, it is determined whether the engine is stopped or just after the IGN SW is turned on. If true, the process proceeds to step 132. If not, it is determined in step 131 whether the BTDC 110 ° crank signal of any cylinder has been received. Which cylinder BTDC 110 ° crank signal is known in step 72 of FIG. In step 132, it is determined whether or not fuel has already been injected into the cylinder that can be injected in the engine stop time region determination determined in step 72 of FIG. 7, and if not, fuel is injected in step 133. Although the injection amount at this time is not shown, an optimal amount for starting is determined based on information such as the engine water temperature and the intake air temperature. If there is a BTDC 110 ° crank signal in step 131, the engine is rotating. In step 134, the injection amount is obtained from the intake air amount, the engine speed, the water temperature, the oxygen state of the exhaust gas, and the like. The valve opening time of the injector 3 is determined. Further, a cylinder capable of injecting the determined valve opening time is obtained, and injection start and end timings are set. Here, the cylinder that can be injected is a cylinder that can be injected earliest among the cylinders whose injection ends before the vicinity of the start of the intake process and for which a predetermined time can be set from this signal. If the rotational speed of the engine has not been determined, it can be determined assuming the rotational speed of the starter. In this embodiment, basically, when the engine rotates, the fuel injection control can be performed immediately according to the crank signal. Further, since the fuel is supplied only to the cylinder that can be ignited next time, it is possible to prevent the fuel from leaving without being burned. When engine rotation becomes unstable at the time of starting, fuel injection by the cam angle θ, that is, step 132 and step 133 may be continued until a predetermined rotation.

  Next, the ignition timing calculation in step 75 of FIG. 7 will be described with reference to the flowchart of FIG. In step 140, it is determined whether a BTDC 70 ° crank signal is received from any cylinder. Which cylinder BTDC 70 ° crank signal is known in step 72 of FIG. If it comes, the timing of ignition to a predetermined cylinder is set in step 141 according to Table 1 above. The timing is determined according to the engine speed, the signal from the air flow sensor 1, the water temperature, and the intake air temperature. If the rotational speed of the engine has not been determined, it can be determined assuming the rotational speed of the starter. In this embodiment, the cylinder of the crank signal is known at step 72 in FIG. 7, and basically, if the engine rotates, the necessary cylinders can be ignited immediately according to the crank signal. Further, in step 74 in FIG. 7, since the fuel has already been supplied to the cylinder to be ignited, the startability is improved.

  In this embodiment, a four-cylinder engine has been described as an example. For example, as shown in FIG. In that case, instead of step 98 in FIG. 9, the injection region may be determined as shown in FIG. Note that the functions from f1 () to f6 () in FIG. 16 are the region determination functions shown in FIG.

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

It is a block diagram of one Example by this invention. It is a block diagram of a crank rotation sensor (reference pulse generating means). It is a block diagram of a cam angle sensor (crank angle detection means). It is a bridge circuit of a magnetoresistive element that outputs a 90 ° phase output. It is another example of a structure of a cam angle sensor. FIG. 4 is a relationship diagram between a process of a four-cylinder engine, a crank signal, and a cam signal. It is a whole control flow figure of fuel injection and ignition processing of the present invention. It is a flowchart which performs a normalization process by the upper and lower limits of a cam signal. It is a cam angle (theta) calculation in a 4-cylinder engine, and the process determination flowchart of each cylinder. It is a figure of the function which calculates | requires an angle from a cam signal. It is a flowchart of the cam angle correction value calculation by a crank signal. FIG. 4 is a relationship diagram between a cam angle θ and BTDC 110 ° of each cylinder. It is a flowchart of a fuel-injection process. It is a flowchart of an ignition timing calculation process. FIG. 6 is a relationship diagram between a process of a 6-cylinder engine, a crank signal, and a cam signal. It is a block diagram of injection area determination of a 6 cylinder engine.

Explanation of symbols

6 ... Crank rotation sensor (reference pulse generating means)
7: Cam angle sensor (crank angle detection means)
11 ... Magnetic flux detection sensor (angle signal generating means)
71 ... Cam signal normalization process 72 ... Cam angle θ calculation process and cylinder process determination process (cylinder operation process determination means)

Claims (4)

In a control method for an internal combustion engine having a control means for controlling an operating state of the internal combustion engine in accordance with a crank angle,
A crank angle detecting means for measuring at least a crank angle or a portion having a correlation with the crank angle when the internal combustion engine is stopped;
Cylinder operating process discriminating means for discriminating the operating process of each cylinder from the measured angle ;
The crank angle detecting means is made of a possible angle signal output means outputs at least two systems or more signal phases different output for angles,
In addition to the angle signal output means, a reference pulse generating means for generating a pulse at a specific angle portion according to rotation is provided.
The angle signal output means detects a rotation angle of a camshaft interlocked with an intake valve and an exhaust valve of an internal combustion engine, and the reference pulse generation means detects an angle of a crankshaft;
The angle signal output means is corrected by the angle measured by the reference pulse generating means,
An internal combustion engine control method, comprising: determining an operation state at the start of the internal combustion engine based on a process determined by the cylinder operation process determination means. The method for controlling an internal combustion engine according to claim 1,
The angle signal output means is a means for calculating the angle from the output values of the two systems, the angle signal output means being composed of two systems of outputs that are 90 ° out of phase with respect to the angle. Method. The method for controlling an internal combustion engine according to claim 1 or 2,
When the internal combustion engine performs fuel injection to the intake port, the internal combustion engine performs fuel injection to the vicinity of the port with respect to the cylinder determined by the cylinder operation process determination means at least in the exhaust process. Control method. The method for controlling an internal combustion engine according to claim 1,
Normalization processing is performed according to the upper and lower limits of the signal input from the angle signal output means, and the crank angle is calculated.
A control method of an internal combustion engine characterized by the above.

Images