JP6404731B2 - Fault diagnosis device for variable valve timing device - Google Patents

Description

  The present invention relates to a failure diagnosis device for a variable valve timing device, and more particularly to an improved failure diagnosis accuracy.

The variable valve timing device is designed to optimize engine performance, fuel efficiency, exhaust gas properties, and other performances. The intake valve and the exhaust valve open / close timing depend on the operating state of the engine. Is continuously variably controlled.
For example, a variable valve timing device uses a hydraulic or electric actuator to rotate an intake camshaft and an exhaust camshaft around a rotation axis with respect to a cam sprocket that rotates in synchronization with a crankshaft. And advance or retard the valve closing timing.

In the valve timing variable device as described above, the actual angular position of the camshaft detected by the cam angle sensor is substantially equal to the target value sequentially set according to the operating state such as the engine speed and the load state. Feedback control is performed so as to match However, in such a valve timing variable device, a failure in which the angular position of the camshaft deviates from the target value due to a failure in the actuator or solenoid valve (a target error failure in which the angular position of the camshaft does not reach the target value, Slow response failure that reaches the target value with a more delayed response may occur.
As a prior art related to failure detection of a valve timing variable device, for example, Patent Document 1 discloses, based on a time diagram of actual values of the angular position of a camshaft, a plurality of subdivided pieces including target error failures and slow response failures. It describes the detection of error type faults.

JP 2005-083380 A

Conventionally, a method is generally used in which a difference between a target value and an actual value of an angular position of a camshaft is monitored and a failure is determined when a state exceeding a threshold value continues for a predetermined time or more.
However, for example, even when a failure occurs in which the angular position of the camshaft is fixed, if the target value at the time of diagnosis is close to the position where the fixing occurs, the target value and the actual value Failure is not detected because the difference is small enough to be considered normal, and failure determination is not performed unless the diagnosis is performed by another method or the engine operating state changes and the target value does not deviate from the fixed position. In some cases, the normal determination is erroneously established without being established, and it is difficult to ensure the diagnostic accuracy.
In view of the above-described problems, an object of the present invention is to provide a failure diagnosis device for a variable valve timing device with improved failure diagnosis accuracy.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a failure diagnosis device for a variable valve timing device for rotationally driving the camshaft relative to the cam sprocket so that the angular position of the camshaft driving the valve of the internal combustion engine approaches a target value. The angular position detection means for detecting the angular position of the camshaft with respect to the cam sprocket, and the difference between the angular position of the camshaft detected by the angular position detection means and the target value exceeds a threshold value. When an error is detected over a predetermined time, an abnormality detection means for detecting an abnormality and a range that the target value can take are divided into a plurality of areas, and the target value is included in any of the plurality of areas In this case, it is possible to provide failure determination means that establishes a normal determination only when the abnormality detection means does not detect an abnormality. A trouble diagnosis device for the variable valve timing apparatus according to claim.
According to this, even if the camshaft is fixed at any angular position, for example, a diagnosis performed in any of a plurality of regions will surely detect an abnormality, and it is erroneously determined to be normal Thus, it is possible to improve diagnostic accuracy when normal diagnosis is performed.

The invention according to claim 2 is characterized in that the failure determination means establishes a normal determination only when the abnormality detection means does not detect an abnormality over one operation cycle from the start to the stop of the internal combustion engine. A failure diagnosis device for a variable valve timing device according to claim 1.
According to this, the diagnosis accuracy can be further improved by accumulating the diagnosis results in each region during one operation cycle and making the determination.

  As described above, according to the present invention, it is possible to provide a failure diagnosis device for a variable valve timing device with improved failure diagnosis accuracy.

It is a figure which shows the structure of the valve drive system of the engine in which the Example of the failure diagnosis apparatus of the valve timing variable apparatus to which this invention is applied is provided. It is a figure which shows the structure of the valve timing variable apparatus provided in the engine of FIG. 1, Comprising: It is a figure which shows a neutral state. It is a figure which shows the structure of the valve timing variable apparatus provided in the engine of FIG. 1, Comprising: It is a figure which shows an advance angle state. It is a figure which shows the structure of the valve timing variable apparatus provided in the engine of FIG. 1, Comprising: It is a figure which shows a retardation state. It is a flowchart which shows operation | movement of the failure diagnosis apparatus of the valve timing variable apparatus of an Example.

  The present invention provides a problem of providing a failure diagnosis device for a variable valve timing device with improved failure diagnosis accuracy. The range in which the target value of the camshaft angular position can be divided into a plurality of regions. The diagnosis was made by comparing the actual values, and the problem was solved by establishing a normal judgment only when no abnormality was detected in all areas.

Embodiments of a failure diagnosis device for a variable valve timing device (hereinafter referred to as “failure diagnosis device”) to which the present invention is applied will be described below.
The failure diagnosis apparatus according to the embodiment is provided, for example, in a four-stroke gasoline engine that is an internal combustion engine mounted as a driving power source in an automobile such as a passenger car, and rotates an intake / exhaust camshaft with respect to a cam sprocket. It diagnoses the failure of the variable valve timing device that continuously changes the valve timing of the exhaust valve.
FIG. 1 is a diagram illustrating a configuration of an engine valve drive system having a failure diagnosis apparatus according to an embodiment.

  As shown in FIG. 1, the engine 1 includes a crankshaft 10, pistons 21, 22, 23, 24, an intake valve 30, an exhaust valve 40, a right intake camshaft 50, a left intake camshaft 60, a right exhaust camshaft 70, It has a left exhaust camshaft 80, a timing belt 90, an actuator 100, and the like.

The engine 1 is, for example, a horizontally opposed four-cylinder engine that is mounted vertically in an engine room provided at the front of the vehicle body.
The crankshaft 10 is an output shaft provided at a central portion (an intermediate portion between the right bank and the left bank) in the vehicle width direction of the engine 1.
The crankshaft 10 includes a main journal portion supported by a main bearing provided in an engine block (not shown), a crankpin to which a connecting rod provided between the pistons 21, 22, 23, and 24 is connected, a crank arm, and a balance. It has a crank web portion formed by integrating weights.
A crank sprocket 11 around which the timing belt 90 is wound is fixed to a front end portion (an end portion opposite to the flywheel side) of the crankshaft 10.

The pistons 21, 22, 23, and 24 are members that are inserted into the cylinder sleeves of the first to fourth cylinders of the engine 1 and reciprocate substantially along the horizontal direction.
The pistons 21, 22, 23, and 24 are sequentially arranged from the front side of the crankshaft 10.
The pistons 21 and 23 of the first cylinder and the third cylinder are arranged in the right bank, and the pistons 22 and 24 of the second cylinder and the fourth cylinder are arranged in the left bank.
The first cylinder and the second cylinder are disposed substantially opposite to each other with the crankshaft 10 interposed therebetween.
The third cylinder and the fourth cylinder are disposed substantially opposite to each other with the crankshaft 10 interposed therebetween on the rear side of the first cylinder and the second cylinder.
The pistons 21, 22, 23, and 24 are connected to the crankshaft 10 via connecting rods.

The intake valve 30 opens and closes an intake port (not shown) for introducing fresh air (combustion air) into the combustion chamber of each cylinder at a predetermined valve timing.
The intake valve 30 is opened by being pressed by the cams of the right intake camshaft 50 and the left intake camshaft 60 via tappets.

The exhaust valve 40 opens and closes an exhaust port (not shown) for discharging exhaust (burned gas) from the combustion chamber of each cylinder at a predetermined valve timing.
The exhaust valve 40 is opened by being pressed by the cams of the right exhaust camshaft 70 and the left exhaust camshaft 80 via tappets.

The right intake camshaft 50 is a rotary shaft-like member having a cam for opening and closing the intake valves 30 of the first cylinder and the third cylinder.
The right intake camshaft 50 is provided above the cylinder head of the right bank, and rotates in synchronization with the half rotation speed of the crankshaft 10.
A cam sprocket 51 around which the timing belt 90 is wound is attached to the front end portion of the right intake camshaft 50.

The left intake camshaft 60 is a rotating shaft member having a cam for opening and closing the intake valves 30 of the second cylinder and the fourth cylinder.
The left intake camshaft 60 is provided above the cylinder head of the left bank, and rotates synchronously with a half rotation speed of the crankshaft 10.
A cam sprocket 61 around which the timing belt 90 is wound is attached to the front end portion of the left intake camshaft 60.

The right exhaust camshaft 70 is a rotary shaft-like member having a cam that opens and closes the exhaust valves 40 of the first cylinder and the third cylinder.
The right exhaust camshaft 70 is provided below the cylinder head of the right bank, and rotates synchronously with a half rotation speed of the crankshaft 10.
A cam sprocket 71 around which the timing belt 90 is wound is attached to the front end portion of the right exhaust camshaft 70.

The left exhaust camshaft 80 is a rotary shaft-like member having a cam for opening and closing the exhaust valves 40 of the second cylinder and the fourth cylinder.
The left exhaust camshaft 80 is provided below the cylinder head of the left bank, and rotates synchronously with a half rotation speed of the crankshaft 10.
A cam sprocket 81 around which the timing belt 90 is wound is attached to the front end portion of the left exhaust camshaft 80.

The timing belt 90 is wound around the crank sprocket 11 of the crankshaft 10 and the crank sprockets 51, 61, 71, 81 of the camshafts 50, 60, 70, 80, and transmits power between them, and each camshaft. A cocked belt that rotates 50, 60, 70, and 80 in synchronization with the crankshaft 10.
In addition, the timing belt 90 is provided with a plurality of idler sprockets, pulleys, tensioners, etc. for adjusting tension.

The actuator 100 is a hydraulic drive mechanism that changes the valve timing by rotating the cam shafts 50, 60, 70, and 80 relative to the cam sprockets 51, 61, 71, and 81 around the rotation axis.
The actuator 100 is of a cam sprocket built-in type provided on the cam sprockets 51, 61, 71, 81 of the cam shafts 50, 60, 70, 80.

Hereinafter, the configuration of the actuator 100 will be described in more detail.
2, 3, and 4 are cross-sectional views of the actuator 100, showing a neutral state (a state in which the camshaft phase is maintained), an advance angle state, and a retard angle state, respectively.
2A is a cross-sectional view taken along the line aa in FIG. 2B, and FIG. 2B is a cross-sectional view taken along a plane including the central axis of the camshaft. Yes (same in FIGS. 3 and 4).
Moreover, in FIG. 3, FIG. 4, the flow of oil is shown by the arrow.
2 to 4, the actuator 100 provided on the right intake camshaft 50 will be described as an example. However, the actuators 100 provided on the other camshafts 60, 70, and 80 have substantially the same configuration. .

  As shown in FIG. 2 and the like, the actuator 100 has a housing 110, a vane 120, an advance oil passage 130, a retard oil passage 140, a solenoid valve 150, and the like, and is controlled by an engine control unit (ECU) 200. ing.

The housing 110 is a housing that constitutes an exterior portion of the actuator 100.
The housing 110 is fixed to the vehicle front side of the cam sprocket 51, and is formed in a cylindrical shape (a cup shape in which the cam sprocket side is opened) with the end opposite to the cam sprocket 51 side closed.
Inside the housing 110, a vane accommodating portion 111 that accommodates the protruding portion 122 of the vane 120 and allows the protruding portion 122 to rotate relative to the housing 110 around the rotation axis of the intake camshaft 50 is formed. ing.
The vane accommodating part 111 is a recessed part formed by denting the inner peripheral surface of the housing 110 to the outer diameter side.
The vane accommodating portions 111 are provided at three locations corresponding to the protruding portions 122 of the vane 120 so as to be distributed at substantially equal intervals in the circumferential direction of the housing 110.

The vane 120 is fixed to the end of the intake camshaft 50 on the cam sprocket 51 side, and rotates relative to the housing 110 around the rotation axis of the intake camshaft 50 by hydraulic pressure, whereby the intake camshaft 50 with respect to the cam sprocket 51 is rotated. The phase (angular position) of the intake valve 30 is changed, and the valve timing of the intake valve 30 is changed.
The vane 120 includes a cylindrical portion 121, a protruding portion 122, and the like that are integrally formed.

The cylindrical portion 121 is a portion fixed to the end portion of the intake camshaft 50 on the cam sprocket 51 side.
The outer peripheral surface of the cylindrical portion 121 is disposed to face the inner peripheral surface in an area other than the vane accommodating portion 111 of the housing 110 through an inevitable interval.

The protruding portion 122 is formed to protrude from the outer peripheral surface of the cylindrical portion 121 to the outer diameter side.
The protrusions 122 are distributed at substantially equal intervals around the vane 120, for example, at three locations.
Each protrusion 122 is accommodated in the vane accommodating portion 111 of the housing 110.
The protruding end portion of the protruding portion 122 is disposed so as to face the inner peripheral surface of the vane housing portion 111 with an interval unavoidably provided.
The circumferential dimension of the protruding portion 122 is formed smaller than the vane accommodating portion 111, and the vane 120 moves in the vane accommodating portion 111 to the front side and the rear side in the rotational direction. In contrast, relative rotation is possible in the advance and retard directions.

The advance oil passage 130 is an oil passage through which oil is introduced from the solenoid valve 150 into the vane accommodating portion 111 of the housing 110 when the valve timing is advanced.
The advance oil passage 130 passes through the intake camshaft 50 and the cylindrical portion 121 of the vane 120 from a cylinder head (not shown) in the space portion on the rear side in the rotational direction with respect to the protruding portion 122 in the vane accommodating portion 111 ( Oil is introduced into the advance chamber.

The retarding oil passage 140 is an oil passage through which oil is introduced from the solenoid valve 150 into the vane accommodating portion 111 of the housing 110 when the valve timing is retarded.
The retarding oil passage 140 passes from the cylinder head (not shown) through the intake camshaft 50 and the cylindrical portion 121 of the vane 120 into the space portion on the front side in the rotational direction with respect to the protruding portion 122 in the vane housing portion 111 ( Oil is introduced into the retarding chamber.

The solenoid valve 150 switches an oil supply oil path pressurized by an oil pump (not shown) according to an instruction from the engine control unit 200 and supplies the oil path to the advance oil path 130 and the retard oil path 140. is there.
The solenoid valve 150 can be switched between a neutral state, an advanced angle state, and a retarded angle state described below by driving a spool with a solenoid.

In the neutral state, as shown in FIG. 2, both the advance oil passage 130 and the retard oil passage 140 are closed, and the oil in the advance chamber and the retard chamber is held. As a result, the vane 120 maintains the current relative angular position with respect to the housing 110.
As shown in FIG. 3, the advance angle state is such that the oil supplied from the oil pump is introduced into the advance angle oil passage 130, the oil is supplied to the advance angle chamber, and the retard angle oil passage 140 is supplied from the retard angle chamber. Drain the oil through As a result, the vane 120 rotates relative to the housing 110 in the advance direction.
In the retarded state, as shown in FIG. 4, the oil supplied from the oil pump is introduced into the retarded oil passage 140 to supply the oil to the retarded chamber, and from the advance chamber to the advanced oil passage 130. Drain the oil through As a result, the vane 120 rotates relative to the housing 110 in the retard direction.

The engine control unit (ECU) 200 controls the engine and its auxiliary equipment in an integrated manner.
The ECU 200 includes an information processing device such as a CPU, a storage device such as a RAM and a ROM, an input / output interface, a bus connecting these, and the like.
The ECU 200 sets a required torque based on the driver's accelerator operation and the like, and controls the throttle opening, the fuel injection amount, the fuel injection timing, the ignition timing, the boost pressure, the EGR amount, and the like according to the set required torque. .
Further, the ECU 200 sets the target angular position of each camshaft 50, 60, 70, 80 with respect to the angular position of the crankshaft 10 based on related parameters such as the engine speed, the vehicle speed, and the throttle opening.
The ECU 200 performs feedback control so that the actual angular position of each camshaft 50, 60, 70, 80 substantially matches the target angular position.
Each camshaft is provided with a cam angle sensor (not shown) that detects its actual angular position.

The ECU 200 has a failure diagnosis function of the variable valve timing device.
The failure diagnosis function has a failure detection function in which the actual angular position of the camshaft deviates from the target angular position. The ECU 200 functions as an abnormality detection unit and a failure determination unit according to the present invention.
Hereinafter, the control at the time of failure diagnosis will be described in detail.
FIG. 5 is a flowchart illustrating the operation of the failure diagnosis apparatus for the variable valve timing apparatus according to the embodiment.
Hereinafter, the steps will be described step by step.

<Step S01: Determination during valve timing feedback control>
The ECU 200 causes the actuator 100 to bring the actual angular positions of the camshafts 50, 60, 70, and 80 (advance amounts and retard amounts with respect to the cam sprockets 51, 61, 71, and 81) closer to the sequentially set target values. It is determined whether or not feedback control for driving is executed.
When the feedback control is being executed, the process proceeds to step S02, and when it is not being executed, step S01 is repeated.

<Step S02: Determination of difference from target value>
The ECU 200 compares the actual angular position detected by the cam angle sensor with respect to the camshaft to be diagnosed with the target value set by the ECU 200, and determines whether or not the difference therebetween is equal to or greater than a preset threshold value. Determine.
If the change is greater than or equal to the threshold value, the process proceeds to step S03, and otherwise, the process proceeds to step S07.

<Step S03: Timer value increment>
The ECU 200 increments (counts up) the timer value of a timer that counts the duration of the state where the difference exceeds the threshold value.
Thereafter, the process proceeds to step S04.

<Step S04: Timer Value Determination>
ECU 200 determines whether or not the timer value is equal to or longer than a preset abnormality determination time.
If the timer value is equal to or greater than the abnormality determination time, the process proceeds to step S05. Otherwise, the process returns to step S01, and the subsequent processing is repeated.

<Step S05: Abnormality detection>
The ECU 200 detects that an abnormality has occurred in the camshaft actuator 100, the solenoid valve 150, and the like.
Thereafter, the process proceeds to step S06.

<Step S06: Failure determination is established>
ECU 200 establishes failure determination, executes predetermined processing such as transition to the fail-safe control mode (save mode), output of an alarm, and the like, and ends a series of processing.

<Step S07: Timer value reset>
ECU 200 resets the timer value.
Thereafter, the process proceeds to step S08.

<Step S08: Abnormality not detected in current zone>
ECU 200 determines which zone of the plurality of zones contains the current target value of the camshaft angular position, and records in the storage device that no abnormality has been detected in the zone.
In the diagnosis by the failure diagnosis apparatus of the embodiment, the range that the target value of the camshaft angular position can take is divided into a plurality of (for example, three) zones.
For example, when the camshaft angular position changes within a range of 60 °, the first zone, the second zone, and the third zone are set every about 20 ° from the advance side, and the abnormality detection is performed at the present time. Sequentially performed in a zone including the target value.
Thereafter, the process proceeds to step S09.

<Step S09: Determination of End of Engine Operation>
The ECU 200 determines whether or not the operation of the engine is finished and one drive cycle (engine start to stop) is completed.
If the engine has ended, the process proceeds to step S10. Otherwise, the process returns to step S01, and the subsequent processing is repeated.

<Step S10: Abnormality non-detection determination in all zones>
ECU 200 determines whether or not abnormality non-detection has been recorded in step S08 at least once in all of the plurality of zones.
If there is a record of non-abnormality detection in all zones, the process proceeds to step S11. Otherwise, the process proceeds to step S12.

<Step S11: Normal determination is established>
ECU 200 establishes normality determination and ends a series of processes.

<Step S12: Determination hold>
The ECU 200 does not make the determination of normality or failure, and ends the series of processes as determination suspension.

As described above, according to the present embodiment, the following effects can be obtained.
(1) A failure diagnosis of the valve timing variable device is performed in each of a plurality of zones obtained by dividing a range that can be taken by the target cam angle, and normality determination is established only when no abnormality is detected in all zones, For example, even when the camshaft is stuck at any angular position, an abnormality is detected in a diagnosis performed in any of a plurality of regions, and it is possible to prevent erroneous determination of normality and improve diagnosis accuracy. Can be improved.
(2) The diagnosis accuracy can be further improved by accumulating the diagnosis results in one operation cycle and making the determination.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The configurations of the valve drive system, the valve timing variable device, and the failure diagnosis device are not limited to the above-described embodiments, and can be changed as appropriate.
For example, the engine cylinder layout (horizontal facing, series, V-type cylinder arrangement and number of cylinders), and camshaft drive method (timing belt, timing chain, gear train, etc.) can be changed as appropriate.
Further, the actuator for changing the angular position of the camshaft is not limited to the hydraulic type as in the embodiment, and may be another type of actuator such as an electric type.
In the embodiments, the engine is, for example, a gasoline engine. However, the present invention can also be applied to a spark ignition engine using a fuel other than gasoline, a diesel engine, or the like.
(2) In the embodiment, the range that can be taken by the target value (target cam angle) of the angular position of the camshaft is divided into, for example, three zones, but diagnosis is performed, but the number of divisions and the division position are not particularly limited. .
In the embodiment, the range that the target cam angle can take is substantially divided into three. However, the distribution may be divided unevenly in consideration of the distribution of the target cam angle on the map.

1 Engine 10 Crankshaft 11 Cranksprocket 21, 22, 23, 24 Piston 30 Intake valve 40 Exhaust valve 50 Right intake camshaft 51 Cam sprocket 60 Left intake camshaft 61 Cam sprocket 70 Right exhaust camshaft 71 Cam sprocket 80 Left exhaust cam Shaft 81 Cam sprocket 90 Timing belt 100 Actuator 110 Housing 111 Vane housing part 120 Vane 121 Cylindrical part 122 Projecting part 130 Advance oil path 140 Delay oil path 150 Solenoid valve 200 Engine control unit (ECU)

Claims (2)

A failure diagnosis device for a variable valve timing device for driving the camshaft to rotate relative to the cam sprocket so that the angular position of the camshaft that drives the valve of the internal combustion engine approaches a target value,
Angular position detection means for detecting an angular position of the camshaft with respect to the cam sprocket;
An anomaly detecting means for detecting an anomaly when a state where a difference between the angular position of the camshaft detected by the angular position detecting means and the target value exceeds a threshold is detected over a predetermined time; and
The range that the target value can take is divided into a plurality of regions, and when the target value is included in any of the plurality of regions, the normality determination is established only when the abnormality detection means does not detect an abnormality. A failure diagnosis device for the variable valve timing device. 2. The valve timing according to claim 1, wherein the failure determination unit establishes a normal determination only when the abnormality detection unit does not detect abnormality during one operation cycle from start to stop of the internal combustion engine. Fault diagnosis device for variable devices.

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