JP4019818B2 - Sensor abnormality detection device of variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve mechanism that changes a valve opening characteristic of an internal combustion engine, and more specifically, a valve characteristic value sensor that detects an actual value of the valve opening characteristic changed by the variable valve mechanism during engine operation. The present invention relates to a sensor abnormality detection device for a variable valve mechanism that determines whether or not there is an abnormality.
[0002]
[Prior art]
A variable valve mechanism for an internal combustion engine that changes the opening characteristics of one or both of the intake and exhaust valves of the internal combustion engine according to the engine operating state during operation and always obtains optimal engine performance regardless of the operating state. Are known. As a variable valve mechanism, for example, one that controls one or more of valve opening / closing timing (valve timing), valve lift amount, valve opening period, and the like of an intake / exhaust valve according to an engine operating state is known. .
[0003]
For example, when changing the valve timing, a method of changing the relative rotation phase of the camshaft with respect to the crankshaft using a hydraulic actuator or the like is used. In addition, in order to change the valve lift amount, the valve opening period, etc., a cam having a cam profile in which the cam lift, the working angle, etc. continuously change in the axial direction is provided on the cam shaft, and the cam shaft uses a hydraulic actuator. For example, a method of changing the valve lift and the valve opening period by moving in the axial direction is used.
[0004]
In order to change the valve opening characteristic according to the engine operating state during engine operation using the variable valve mechanism as described above, a valve characteristic value sensor for detecting the value of the valve opening characteristic of the engine is provided. It is preferable to perform feedback control so that the actual valve opening characteristic value detected by this sensor becomes a target value corresponding to the engine operating state.
[0005]
However, when the valve opening characteristic is feedback controlled using such a valve characteristic value sensor, if the sensor malfunctions, the valve opening characteristic cannot be controlled according to the engine operating state, resulting in deterioration of engine performance. As a result, exhaust properties deteriorate. Therefore, when the variable valve mechanism is controlled using the valve characteristic value sensor, it is necessary to detect the abnormality of the sensor at an early stage.
[0006]
An example of an apparatus for detecting an abnormality of this type of valve characteristic value sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-097096.
[0007]
The sensor abnormality detection device disclosed in the publication detects an abnormality of a valve timing sensor of a variable valve timing device that changes the opening / closing timing of an intake valve or an exhaust valve by changing a relative rotational phase of a camshaft and a crankshaft. Is.
[0008]
The camshaft that drives the cylinder valve is driven from the crankshaft via a gear or a belt and rotates in synchronization with the crankshaft. The variable valve timing device disclosed in the publication provides means for increasing or decreasing the crank angle at which the intake valve or exhaust valve opens and closes by changing the phase difference between the rotation of the crankshaft and the camshaft. The timing is controlled so as to be an optimum value determined in advance according to the driving state.
[0009]
The valve timing sensor disclosed in the publication includes sensors that are provided on both the crankshaft and the camshaft and generate pulse signals at every fixed rotation angle. Further, these sensors generate a reference position signal when the crankshaft and the camshaft are respectively in predetermined rotational positions. For this reason, by detecting the phase difference between the reference position signals of the crankshaft and the camshaft, the rotational phase difference between the camshaft and the crankshaft, that is, the valve timing can be detected.
[0010]
In the apparatus of the publication, the variable valve timing apparatus is feedback-controlled using the valve timing value detected by the sensor. For this reason, if an abnormality occurs in the valve timing sensor, the optimum valve timing cannot be obtained, and the engine output and the exhaust properties deteriorate.
[0011]
In the apparatus of the publication, in order to prevent this, the number of rotation pulse signals output from the other sensor during a specific rotation pulse signal (for example, a reference position signal) output from one of the crankshaft or camshaft sensors. Is detected, and it is determined that an abnormality has occurred in the sensor when the number of times is outside the specified value.
[0012]
That is, even if the rotational phase of the crankshaft and the camshaft changes, as long as both shafts rotate synchronously, the other rotates while one (for example, the crankshaft) rotates by a specific rotational angle. The angle is the same. The device of this publication pays attention to this relationship, and the number of rotation pulse signals output from the other sensor during a specific rotation pulse signal output from one sensor of the crankshaft or camshaft is outside the specified value. In some cases, it is determined that an abnormality has occurred in the sensor.
[0013]
[Problems to be solved by the invention]
In the sensor abnormality detection device disclosed in Japanese Patent Application Laid-Open No. 2000-097096, an abnormality occurs in the valve timing sensor that detects the valve timing of the engine when the relationship between the rotation pulse signals of the crankshaft and the camshaft becomes out of regulation. It is judged that.
[0014]
However, although the valve timing sensor can accurately detect the presence or absence of a sensor abnormality by the method described in the above publication, other valve opening characteristics such as a valve lift amount or a valve opening period are described in the above publication. The method cannot detect the presence or absence of sensor abnormality.
In view of the above problems, the present invention provides an abnormality detection device that can accurately detect the presence or absence of abnormality of a valve characteristic value sensor that detects valve opening characteristics such as a valve lift amount and a valve opening period in a variable valve mechanism. It is an object.
[0015]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a sensor abnormality detection device for a variable valve mechanism that changes a valve opening characteristic including at least one of a valve lift amount and a valve opening period of a cylinder intake valve of an internal combustion engine. There,
A valve characteristic value sensor for detecting an actual value of the valve opening characteristic during engine operation;
Intake air amount detection means for detecting the amount of fresh air taken into the engine;
Means for detecting the engine speed;
Means for detecting intake pipe pressure;
The detected engine speed and intake pipe pressure When Intake amount actually inhaled into the engine based on Based on the engine speed, the intake pipe pressure, and the valve characteristic sensor output. Intake air amount calculating means for calculating the amount of EGR gas contained in the intake air amount;
Determination of whether or not an abnormality has occurred in the valve characteristic value sensor based on the fresh air amount detected by the intake air amount detection unit and the intake air amount and EGR gas amount calculated by the intake air amount calculation unit Means,
There is provided a sensor abnormality detecting device for a variable valve mechanism comprising:
[0016]
That is, according to the first aspect of the present invention, it is determined whether there is an abnormality in the valve characteristic value sensor that detects the value of the valve opening characteristic including at least one of the valve lift amount or the valve opening period. Both the valve lift amount and the valve opening period have a great influence on the amount of intake air actually taken into each cylinder. For example, if the engine speed and the intake pipe pressure are the same, the actual intake amount of the engine changes according to valve opening characteristics such as the valve lift amount and the valve opening period. For this reason, for example, if the values of the engine speed, the intake pipe pressure, and the valve opening characteristics are known, the intake amount actually taken into the cylinder can be calculated.
[0017]
Further, the amount of intake actually taken into the cylinder is the sum of the amount of internal EGR gas and the amount of fresh air. Here, the internal EGR occurs because the exhaust gas flowing back to the intake port during the cylinder exhaust stroke is sucked into the cylinder again during the intake stroke, and the internal EGR gas amount is Engine speed, It can be calculated if the intake pipe negative pressure and the valve opening characteristic value are known.
The internal EGR gas amount can also be calculated by subtracting the amount of fresh air sucked into the cylinder from the amount of intake actually sucked into the cylinder.
[0018]
Therefore, for example, the actual cylinder intake air amount is calculated based on the intake pipe negative pressure, the engine speed, and the valve opening characteristic value, and the new air amount detected using an air flow meter or the like is subtracted from the cylinder intake air amount. Thus, the internal EGR gas amount is also calculated.
On the other hand, the internal EGR gas amount is equal to the intake pipe negative pressure as described above. With engine speed It can be directly calculated from the valve opening characteristic value.
For this reason, the internal EGR gas amount obtained by subtracting the fresh air amount from the cylinder intake amount, the intake pipe negative pressure, With engine speed If there is a difference of a predetermined value or more between the internal EGR amount directly calculated based on the valve opening characteristic value, the valve opening characteristic value detected by the valve characteristic value sensor is different from the actual value. It can be determined that an abnormality has occurred in the valve characteristic value sensor.
[0019]
As described above, according to the present invention, two types of gas amounts (intake amount and internal EGR amount) are calculated based on the value of the valve characteristic value sensor output, and an abnormality of the valve characteristic value sensor is obtained by comparing the results. The presence or absence of abnormalities is judged.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram when the air-fuel ratio control apparatus of the present invention is applied to a four-cylinder gasoline engine for automobiles, and FIG. 2 is a schematic diagram showing a schematic configuration of an intake system of the engine of FIG.
[0024]
1 and 2, reference numeral 1 denotes an internal combustion engine, 8 denotes a combustion chamber formed in a cylinder of the engine 1, 2 denotes an intake valve, and 3 denotes an exhaust valve. In this embodiment, a so-called DOHC (double overhead camshaft) type valve operating system in which the drive camshaft 6 and the exhaust valve drive camshaft 7 of the intake valve 2 are provided independently is employed. . . 1 and 2, reference numeral 4 denotes an intake valve driving cam provided on the camshaft 6, and 5 denotes an exhaust valve driving cam provided on the camshaft 7.
[0025]
Further, 13 is a crankshaft, 15 is a fuel injection valve, and 17 is a rotational speed sensor for detecting the engine rotational speed. 1 and 2, reference numeral 18 denotes an intake pressure sensor 16 that detects the intake pipe pressure of the engine 1, an air flow meter that detects the intake air amount of the entire engine, 22 an ECU (electronic control unit), 50 a cylinder, 52 is an intake pipe, 53 is a surge tank, 51 is an intake manifold that connects the surge tank and the intake port of each cylinder. Further, 54 is an exhaust pipe, 55 is a spark plug, 56 is provided with an independent actuator (not shown), and the opening degree is independent of the accelerator opening degree (accelerator pedal depression amount) according to a control signal from the ECU 22 described later. The throttle valve can be changed.
[0026]
In this embodiment, the exhaust valve driving cam 5 is a normal cam having a uniform cam profile in the camshaft axial direction, whereas the intake valve driving cam 4 is a camshaft 6 The cam profile continuously changes along the axial direction.
[0027]
FIG. 3 is a view showing a detailed shape of the intake valve driving cam 4. As shown in FIG. 3, the cam profile of the intake valve cam 4 of the present embodiment changes along the camshaft central axis direction, and the nose height and operating angle of the cam profile change from the right end to the left end in FIG. The cam profile is set so as to continuously increase. For this reason, the valve lift amount and the valve opening period of the intake valve 2 change according to the contact position of the intake valve 2 with the cam 4 of the valve lifter, and the valve lift valve moves as the contact position of the valve lifter moves from the right end to the left end of the cam. The lift amount is large, and the valve opening period of the intake valve is long.
[0028]
In the present embodiment, the valve lift amount and the valve opening period of the intake valve 2 are moved by moving the camshaft in the axial direction during engine operation using a variable valve mechanism (hereinafter referred to as “variable valve mechanism 9”). It is possible to change the valve opening characteristic value such as. That is, by using the variable valve mechanism 9, the camshaft 6 is slid in the axial direction during engine operation to change the contact position between the intake valve cam 4 and the valve lifter, and the cam profile used for driving the intake valve 2 is changed. It is possible to change.
[0029]
When the valve lift amount of the intake valve 2 is increased, the amount of air sucked into the cylinder is increased even if the valve opening period of the intake valve is the same. Further, when the cam operating angle (the intake valve opening period) becomes large (long), the amount of air taken into the cylinder increases even if the valve lift amount is the same. In the present specification, intake valve operation parameters that affect the intake air amount in the cylinder, such as the intake valve lift amount and the operating angle (opening period) described above, are referred to as valve opening characteristic values.
[0030]
FIG. 4 is a cross-sectional view showing the operating principle of the variable valve mechanism 9. In FIG. 4, 30 is a magnetic body connected to the intake valve camshaft 6, 31 is a solenoid for driving the magnetic body 30, and 32 is a compression for biasing the magnetic body 30 toward the right side of FIG. It is a spring. In the variable valve mechanism of this embodiment, when the coil 31 is energized, the magnetic body 30 moves to the left in FIG. 4 against the biasing force of the spring 32, and the contact position between the valve lifter of the intake valve 2 and the cam 4. Is displaced in the camshaft axial direction. Since the amount of movement of the magnetic body 30 changes according to the energization current to the solenoid 31, in this embodiment, by controlling the energization current to the solenoid 31, the contact position between the valve lifter of the intake valve 2 and the cam 4, that is, The valve opening characteristic value of the intake valve 2 can be controlled. In this embodiment, as the energization current to the solenoid 31 increases, the camshaft 6 moves to the left in FIGS. 3 and 4 and the valve lift amount and the valve opening period of the intake valve 2 decrease. Therefore, in the present embodiment, the intake air amount of each cylinder of the engine 1 is maximized while the solenoid 31 is not energized, and the intake air amount of each cylinder decreases as the energization current increases.
[0031]
1 is a valve characteristic value sensor for detecting a valve opening characteristic value (valve lift amount, valve opening period) of the intake valve 2. As described above, in the present embodiment, the valve opening characteristic value of the intake valve 2 changes in accordance with the amount of movement of the camshaft 6 in the axial direction. A characteristic value is also determined. For this reason, in this embodiment, as the valve characteristic value sensor 16, an axial position sensor that detects the axial position (movement amount) of the intake valve camshaft 6 is used, and the ECU 22 detects the camshaft detected by the valve characteristic value sensor 16. Using the axial position, valve opening characteristic values such as a valve lift amount and a valve opening period of the intake valve 2 are calculated based on a previously stored relationship.
[0032]
In the present embodiment, the ECU 22 is a known type of microcomputer in which a RAM, a ROM, and a CPU are connected via a bidirectional bus, and the valve opening characteristic value calculated from the output of the valve characteristic value sensor 16 indicates the engine operating state. In addition to controlling the variable valve mechanism 9 so as to obtain an optimal value determined according to the above, it is determined whether or not a valve characteristic value sensor 16 described later is abnormal.
[0033]
Next, abnormality determination of the valve characteristic value sensor 16 of the present embodiment will be described.
As described above, the ECU 22 feedback-controls the valve opening characteristic value of the engine based on the output of the valve characteristic value sensor 16 (the axial position of the camshaft). For this reason, if an abnormality occurs in the valve characteristic value sensor 16 and the sensor output does not correspond to the actual valve opening characteristic value (in this embodiment, the axial direction position of the camshaft), the valve opening characteristic value is set to the engine operating state. The engine cannot be controlled to the optimum value, and the engine output and exhaust properties deteriorate.
[0034]
In the present embodiment, the ECU 22 determines whether or not the valve characteristic value sensor 16 has an abnormality in the output by a method described below, and if an abnormality has occurred, warns the driver, The engine is prevented from operating for a long time in a state where an abnormality has occurred.
FIG. 5 is a flowchart for specifically explaining the sensor abnormality determination operation of the present embodiment. This operation is performed as a routine executed by the ECU 22 at regular intervals.
[0035]
When the operation starts in FIG. 5, in step 501, the current engine intake air amount (fresh air amount) Gam from the air flow meter 19, the engine speed Ne from the rotation speed sensor 17, and the intake pipe from the intake pressure sensor 18. The pressure Pm is read, and the current valve characteristic value (camshaft axial position) VL is read from the valve characteristic value sensor 16.
[0036]
In step 503, reading is performed. Machine The intake air amount Ga actually sucked into the engine is calculated from the relationship rotational speed Ne and the intake pipe pressure Pm using the relationship stored in advance in the ROM of the ECU 22. The amount of intake air actually taken into the engine cylinder is the sum of the fresh air amount and the internal EGR amount. The machine This is a function of the function speed Ne and the intake pipe pressure Pm. In the present embodiment, the intake air amount Ga is previously experimentally determined. And N The relationship between e and Pm is obtained and stored in the ROM of the ECU 22 in the form of a numerical table or the like. In step 503, the value of the intake air amount Ga is read from this table.
[0037]
In step 505, step 503 is performed. P Using the intake air amount Ga calculated based on m and Ne and the fresh air amount Gam detected by the air flow meter 19, a determination internal EGR amount calculated value Gegr1 is calculated as Gegr1 = Ga−Gam.
Further, in step 507, the second internal EGR amount Gegr2 for determination is calculated from the valve opening characteristic value VL detected by the valve characteristic value sensor 16, the intake pipe pressure Pm, and the engine speed Ne.
[0038]
For example, when the valve opening characteristic value is large (in this embodiment, the valve lift amount is large and the valve opening period is long), the amount of burned gas that flows back to the intake port during the exhaust stroke is larger than when it is small. Therefore, the internal EGR amount increases. Further, the lower the intake pipe pressure Pm, the greater the amount of burnt gas that flows back to the intake port. For this reason, the internal EGR amount is uniquely determined if the valve lift characteristic value, the intake pipe pressure, and the engine speed are determined. In the present embodiment, the relationship between the internal EGR amount and VL, Pm, and Ne is obtained in advance through experiments and stored in the ROM of the ECU 30 in the form of a numerical table. In step 507, the internal EGR amount is read from this numerical map and stored as Gegr2.
[0039]
Incidentally, the first internal EGR amount Gegr1 calculated in step 505 and the second internal EGR amount Gegr2 calculated in step 507 should be essentially the same value, and there is a difference of a certain amount or more between these values. If so, the output of the valve characteristic value sensor 16 that is the basis for the calculation of Gegr2 (or any of the intake pipe pressure, the rotation speed, and the fresh air amount detected by the air flow meter that is the basis for the calculation of Gegr1) This is probably because of However, since the intake pipe pressure, the engine speed, the air flow meter output, etc. are actually determined separately, in this case, it is assumed that these devices are normal and there is a difference between Gegr1 and Gegr2. If it has occurred, it is determined that some abnormality has occurred in the valve characteristic value sensor 16.
[0040]
That is, in step 509, it is determined whether or not a difference equal to or greater than a predetermined value K1 has occurred between Gegr1 and Gegr2. If | Gegr1-GEGR2 |> K1, the process proceeds to step 511, where the flag XF The value is set to 1 and the current operation is terminated.
[0041]
Here, when the value of the flag XF is set to 1 (abnormal), a warning lamp arranged in the vicinity of the driver's seat is turned on by an operation (not shown) separately executed by the ECU 22, and the driver is notified of the valve characteristic value sensor 16. It is notified that an abnormality has occurred. If | Gegr1−GEGR2 | ≦ K1 in step 509, that is, it can be determined that there is no abnormality in the valve characteristic value sensor 16 in this determination operation, the value of the flag XF in step 513 Is reset to 0 and the operation is terminated.
[0042]
As described above, since the abnormality of the valve characteristic value sensor 16 can be easily and reliably determined by executing the determination operation of FIG. 5, it is possible to detect the abnormality of the valve characteristic value sensor 16 at an early stage. It becomes.
In the present embodiment, the presence / absence of the abnormality of the sensor is determined using the internal EGR gas amount Gegr2 calculated based on the output VL of the valve characteristic value sensor 16, but instead of the internal EGR gas amount, the valve characteristic is determined. Sensor abnormality determination can also be performed by calculating the fresh air amount Gal based on the output VL of the value sensor 16.
[0043]
That is, the amount of fresh air sucked into the engine is a function of the engine speed Ne, the throttle valve 56 opening TH, and the valve characteristic value VL. Therefore, a relationship between the amount of fresh air sucked into the engine and Ne, TH, VL is obtained in advance by experiments or the like, and this relationship is used to calculate the engine characteristics based on the valve characteristic value sensor 16 output and Ne, TH. When the intake air amount (fresh air amount) Gal is calculated and the difference between the fresh air amount Gam actually detected by the air flow meter 19 and the calculated value Gal exceeds a predetermined value, an abnormality occurs in the valve characteristic value sensor 16. It can also be determined that
[0044]
Further, for example, when the ignition switch at the time of starting the engine is turned on or immediately after the engine is stopped, the variable valve mechanism 9 is driven and the camshaft is at a position where the valve opening characteristic value is maximized (full stroke position). It is also possible to determine whether there is an abnormality in the valve characteristic value sensor based on whether or not the output of the valve characteristic value sensor 16 at the full stroke position matches the output at the full stroke position stored in advance. is there.
[0045]
Next, another embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a diagram showing a schematic configuration of the main part of the apparatus when an electric motor (for example, a stepper motor) is used as the actuator of the variable valve mechanism 9.
[0046]
In FIG. 6, 6 indicates a camshaft. In the present embodiment, the camshaft 6 is connected to a stepper motor 65 via a ball screw mechanism 61 and a gear 63. The ball screw mechanism 61 includes a sleeve 61 a that instructs the camshaft 6 to rotate freely and moves in the axial direction according to the rotational motion of the motor 65 transmitted through the gear 63.
[0047]
During the engine operation, the stepper motor 65 receives the drive pulse signal transmitted from the ECU 22 and rotates by an angle corresponding to the signal. This rotation is transmitted to the housing 61 b of the ball screw mechanism 61 through the gear 63. The sleeve 61a of the ball screw mechanism 61 is engaged with the housing 61b via the ball screw 61c. For this reason, when the housing 61b of the ball screw mechanism 61 rotates, the sleeve 61a moves in the axial direction together with the camshaft while the camshaft 6 is rotatably supported.
[0048]
In the present embodiment, the magnetic core 16a of the valve characteristic value sensor 16 is connected to the end of the sleeve 61a. A detection coil 16b is disposed around the core 16a. When the core 16a moves together with the camshaft, the immersion length in the coil 16b of the core 16a changes. As a result, a voltage corresponding to the immersion length of the core 16a is generated in the coil 16b. Since the immersion length of the core 16a, that is, the movement amount of the cam shaft has a one-to-one relationship with the valve characteristic value, the valve characteristic value can be detected by the voltage generated in the coil 16a.
[0049]
In the present embodiment, in addition to the valve characteristic value sensor 16, the stepper motor 65 is provided with a rotation angle sensor 67 that detects the rotation angle of the motor 65. The rotation angle sensor 67 of the present embodiment is of a pulse type or the like that generates a pulse signal at every fixed rotation angle, and integrates the number of pulses from when the rotation angle sensor 67 is at a certain reference position to the present. By doing so, the rotation angle of the current position from the reference position can be known.
[0050]
Usually, since the gear 63 that connects the motor 65 and the housing 61b of the ball screw mechanism 61 has a large gear ratio, the ball screw mechanism housing extends from the position where the valve opening characteristic value is minimized to the position where it is maximized. In order to rotate 61b, the motor 65 rotates one rotation (360 °) or more. However, in the present embodiment, as described above, the pulse count type rotation angle sensor 67 is used. The rotation angle of the motor 65 can be detected.
[0051]
In this embodiment, the presence or absence of abnormality of the valve characteristic value sensor 16 is determined in the following procedure during engine operation.
(1) Reference position learning
First, when the ignition switch before starting the engine is turned on, the ECU 22 moves the variable valve mechanism 9 to the position where the camshaft moves to the rightmost in FIG. 6 (in this embodiment, the position where the valve characteristic value becomes maximum). This position is stored as a reference position for the rotation angle sensor 67 and the valve characteristic value sensor 16.
[0052]
(2) Rotation angle pulse integration
The ECU 22 integrates (adds or subtracts depending on the rotation direction) the output pulses of the rotation angle sensor 67 after the engine is started. This integrated value always represents the current rotational position (rotation angle) of the motor.
[0053]
(3) Abnormality judgment
The ECU 22 calculates the current valve characteristic value (camshaft axial position) from the rotation angle sensor 67 output pulse integrated value at regular intervals, and compares it with the current valve characteristic value detected by the valve characteristic value sensor. Do. If there is a difference of a predetermined value or more between the current valve characteristic value calculated from the rotation pulse sensor 67 output pulse integrated value and the current valve characteristic value detected by the valve characteristic value sensor 16, the valve characteristic value It is determined that an abnormality has occurred in the sensor 16.
[0054]
In this case, for example, when an abnormality occurs in an element other than the sensor 16 such as a meshing abnormality of the ball screw mechanism or an abnormality of the gear, an abnormality occurs in the output of the sensor 16, so that these abnormality can be accurately detected. .
[0055]
【The invention's effect】
According to the invention described in each claim, it is possible to accurately detect whether or not there is an abnormality in a valve characteristic value sensor that detects valve opening characteristics such as a valve lift amount and a valve opening period in a variable valve mechanism during engine operation. There is a common effect that is possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment in which the present invention is applied to an automobile gasoline engine.
2 is a schematic diagram showing a schematic configuration of an intake system of the engine of FIG. 1. FIG.
FIG. 3 is a diagram showing a detailed shape of an intake valve driving cam.
FIG. 4 is a cross-sectional view showing the operating principle of the variable valve mechanism.
FIG. 5 is a flowchart illustrating an example of a sensor abnormality determination operation.
6 is a view schematically showing a configuration of an embodiment different from FIG. 4 of the variable valve mechanism.
[Explanation of symbols]
1. Internal combustion engine
2 ... Intake valve
3 ... Exhaust valve
4,5 ... cam
6,7 ... Camshaft
8 ... Combustion chamber
9 ... Variable valve mechanism
16 ... Valve characteristic value sensor
22 ... Electronic control unit (ECU)

Claims (1)

A sensor abnormality detection device for a variable valve mechanism that changes a valve opening characteristic including at least one of a valve lift amount and a valve opening period of a cylinder intake valve of an internal combustion engine,
A valve characteristic value sensor for detecting an actual value of the valve opening characteristic during engine operation;
Intake air amount detection means for detecting the amount of fresh air taken into the engine;
Means for detecting the engine speed;
Means for detecting intake pipe pressure;
With actually calculated amount of intake air sucked into the engine based on the intake pipe pressure and the detected engine speed, intake air amount based on the engine speed and the intake pipe pressure and the valve characteristic sensor output Intake air amount calculating means for calculating the amount of EGR gas contained therein;
Determination of whether or not an abnormality has occurred in the valve characteristic value sensor based on the fresh air amount detected by the intake air amount detection unit and the intake air amount and EGR gas amount calculated by the intake air amount calculation unit Means,
A sensor abnormality detection device for a variable valve mechanism comprising:

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