JP2002238288A - Fault control apparatus of displacement sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change conduction control based on a displacement sensor to that based on the current/voltage of an electromagnet when the displacement sensor has been judged to be in failure. SOLUTION: This fault control apparatus of the displacement sensor has a machine element that can be displaced, the displacement sensor that detects displacement in the machine element, and a fault judgment means for judging that the displacement sensor has failed when output from the displacement sensor at specific timing does not exist within a specific range that is set based on the specific timing. The fault control apparatus is advantageously applied to the displacement sensor for detecting the displacement of an armature in an electromagnetic actuator. In the case of the faults, the conduction control based on the displacement of the armature is changed to that based on change in the current and voltage of the electromagnet, thus inhibiting deterioration in engine performance as much as possible, and continuing the operation of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure determination of a displacement sensor for detecting a displacement of a mechanical element and control at the time of failure, and more specifically, to a displacement for detecting a displacement of a mechanical element driven by an electromagnetic actuator. The present invention relates to a displacement sensor failure control device that executes sensor failure determination and control at the time of failure.

[0002]

2. Description of the Related Art As one of methods for detecting displacement of a mechanical element, a method using a magnet and a magnetic sensor has been proposed. According to this method, a magnet magnetized in the direction in which the mechanical element is displaced is arranged, and a change in magnetic flux from the magnet is detected by a magnetic sensor, thereby detecting the displacement of the mechanical element. A general method for determining a failure in such a displacement sensor that detects the displacement of a mechanical element sets an allowable range for the sensor output, and determines that a failure has occurred when the sensor output falls outside the range.

[0003] On the other hand, in general, an actuator for driving a mechanical element is electromagnetically driven. The drive by the electromagnetic actuator drives a mechanical element by the attractive force of the electromagnet generated by exciting the coil of the electromagnet by an electric signal. Since the driving timing and driving force can be changed in any way by controlling the electric signal, it is widely used in fields where precise timing control and variable control are desired. In particular, as a future possibility, it is desired to apply an electromagnetic actuator to an intake / exhaust valve of an engine. When the intake and exhaust valves are driven by the electromagnetic actuator, the valve timing can be variously controlled, and the output characteristics and fuel efficiency of the engine can be improved.

An electromagnetic actuator typically includes a movable iron piece or armature sandwiched between a pair of springs in a state where an offset load is applied in advance, at an intermediate portion between opposed electromagnets, and a valve is connected to the armature. ing.
Here, since the valve-opening operation and the valve-closing operation are performed in a similar manner, a driving method that has been conventionally performed only for the valve-opening operation will be described.

[0005] 1) The magnetic attraction force exerted on the armature by the valve-closing side electromagnet overcomes the repulsive force of the pair of springs to attract and seat the armature. As a result, the valve closes.
The armature is released from the seated state when the power supply to the electromagnet is subsequently stopped or the like, and starts displacement in a cosine function by the action of a pair of springs. 2) At a predetermined timing according to the displacement of this armature,
An appropriate current is supplied to the valve-opening electromagnet to grow a magnetic flux for generating an attractive force. 3) The magnetic flux grows rapidly as the armature approaches the valve-opening electromagnet that is generating this magnetic flux. The work by the attraction force of the valve-opening electromagnet overcomes the sum of the slight work of trying to pull back the armature due to the residual magnetic flux of the valve-closing side electromagnet and the mechanical loss, which is the majority of the work. Sit on the valve side electromagnet. At this time, the valve is opened. 4) When the armature is seated, a constant current (called a holding current) for holding the armature is supplied to the valve-opening electromagnet at an appropriate timing, and the armature is kept held.

Generally, driving of a valve by an electromagnetic actuator is realized by detecting the displacement of the valve by a displacement sensor and controlling the timing of starting and stopping the current supply to the electromagnet based on the detected displacement. You. Therefore, a displacement sensor is required to detect displacement with high accuracy.

However, it is necessary to operate the engine even when a failure occurs in the displacement sensor. in this case,
Since the valve cannot be driven based on the output of the displacement sensor, the valve needs to be driven in another alternative method.

As a method of controlling energization of an electromagnet without using a displacement sensor, for example, Japanese Patent Laid-Open No. 2000-4573
JP-A No. 3 (2003) discloses that, of the electromagnets on the valve-opening side and the valve-closing side, stopping the supply of the holding current to one of the electromagnets and then supplying the operating current (current for attracting the armature) to the other electromagnet. A method is disclosed in which the delay time until the start of the operation is corrected and the energization timing is optimized. Specifically, when a current is supplied to the electromagnet, a current flowing through the electromagnet is measured, and a temporary “dent” of the measured current is detected. After the energization of the holding current of one electromagnet is stopped, the operating current of the
Is measured, and the delay time is corrected and set based on the measured time.

Japanese Patent Application Laid-Open No. 2000-46230 discloses measuring an actual current actually flowing through an electromagnet and detecting a temporary "recess" of the measured actual current. Based on the timing at which the "dent" is detected, the timing of switching from the operating current flowing through the electromagnet to attract the armature to the holding current flowing through the electromagnet to hold the armature is set. Further, the operating current supplied in the next cycle is corrected based on the size of the “dent”.

Further, Japanese Patent Application Laid-Open No. 2000-283327 discloses a method for detecting seating of an armature without using a displacement sensor. More specifically, in the armature holding operation, the switching control of the driving voltage is performed so that the driving current flowing through the electromagnet is substantially constant, and it is detected that the armature is seated based on a parameter corresponding to the duty ratio of the driving voltage. I do. When the electromagnet is driven at a constant current, the switching waveform of the driving voltage changes due to the impedance change due to the seating of the armature.

[0011]

When an actuator for electromagnetically driving a valve is mounted on an engine, the performance of the engine mainly depends on the fuel consumption, emission and output characteristics which vary with the accuracy of valve timing, and the seating speed. Depends on vibration noise and durability. The accuracy of the valve timing is mainly determined by the accuracy of the timing at which the application of the holding current to the electromagnet is stopped, and the seating speed is mainly determined by the accuracy of the timing at which the electromagnet is energized to attract the armature.

On the other hand, since the drive control of the electromagnetic valve is generally performed based on the displacement, high accuracy is required for the displacement detection. However, when a failure occurs in the displacement sensor, it becomes impossible to appropriately control the valve timing and the seating speed, which greatly affects the performance of the engine. Therefore, when a failure occurs in the displacement sensor, it is necessary to find it early.

Further, it is necessary to drive the electromagnetic valve so that the operation of the engine is continued even when it is determined that a failure has occurred in the displacement sensor.

Therefore, there is a need for a displacement sensor failure control device capable of detecting a failure of a displacement sensor at an early stage and driving a valve so as to minimize a decrease in engine performance even if a failure occurs. Have been.

[0015]

In order to solve the above-mentioned problems, a displacement control device for a displacement sensor according to the present invention comprises: a displaceable mechanical element; a displacement sensor for detecting the displacement of the mechanical element; Failure determination means for determining that a failure has occurred in the displacement sensor when an output from the displacement sensor at a predetermined timing is not within a predetermined range set based on the predetermined timing. .

According to the first aspect of the present invention, since the output of the displacement sensor is inspected at a predetermined timing, a failure of the displacement sensor can be found early and surely.

According to a second aspect of the present invention, in the failure control device for a displacement sensor according to the first aspect of the present invention, a pair of springs working in opposite directions, a neutral position connected to the springs and given by the springs in a non-operating state. An armature coupled to the mechanical element, and an electromagnetic actuator having a pair of electromagnets for displacing the armature between two end positions, wherein the displacement sensor detects displacement of the armature. The displacement of the mechanical element is detected.

According to the second aspect of the present invention, when the valve is driven by the electromagnetic actuator, the output of the displacement sensor is inspected at a predetermined timing, so that the failure of the displacement sensor can be found early and surely.

According to a third aspect of the present invention, in the displacement sensor failure control device according to the second aspect of the present invention, the predetermined timing
The predetermined range is set based on the neutral position of the armature, including the timing at which the electromagnetic actuator is activated.

According to the third aspect of the present invention, the failure determination of the displacement sensor is executed at the timing when the electromagnetic actuator is activated, so that the failure of the displacement sensor caused by the middle point deviation of the armature can be determined early. Can be.

According to a fourth aspect of the present invention, in the failure sensor for a displacement sensor according to the second aspect of the present invention, the predetermined timing
The predetermined range is set based on a predetermined standard value, including a timing at which the armature held by one of the pair of electromagnets is opened.

According to the fourth aspect of the present invention, the failure determination of the displacement sensor is performed at the timing when the armature is released. Therefore, it is possible to periodically determine the failure of the displacement sensor that causes a deviation of the inclination of the sensor output. it can.

According to a fifth aspect of the present invention, in the fault sensor for a displacement sensor according to the second aspect of the present invention, the predetermined timing
The predetermined range includes a timing at which an armature held by one of the pair of electromagnets is released and a timing at which an armature held by the other of the pair of electromagnets is released, wherein the predetermined range includes an armature held by one of the electromagnets. Is set based on a predetermined standard value for the timing at which the armature is opened, and a predetermined standard value for the timing at which the armature held by the other of the electromagnets is opened.

According to the fifth aspect of the present invention, it is possible to check whether or not the sensor output is appropriate in the range detected by the displacement sensor. Therefore, it is possible to more accurately determine a failure of the displacement sensor which causes a deviation of the inclination of the sensor output. it can.

According to a sixth aspect of the present invention, in the failure control device for a displacement sensor according to the fourth or fifth aspect of the present invention, the standard value is set when the displacement sensor is operating normally.
The configuration is such that it is determined in advance based on the sensor output detected at the predetermined timing.

According to the sixth aspect of the present invention, since the failure determination of the displacement sensor is performed based on the standard value when the displacement sensor is operating normally, the failure of the displacement sensor can be more accurately determined. it can.

According to a seventh aspect of the present invention, in the displacement sensor failure control device according to the second aspect of the present invention, first energization control means for controlling energization of the electromagnet based on an output from the displacement sensor, and the electromagnet And a second energization control unit for controlling energization of the electromagnet based on a change in one or both of the current and the voltage of the electromagnet. The power supply control by the power supply control means is prohibited, and a failure control means for performing the power supply control by the second power supply control means is provided.

According to the invention of claim 7, when it is determined that the displacement sensor has failed, the valve drive can be controlled by the second energization control, so that the running of the vehicle can be continued without lowering the engine performance. Can be done.

According to an eighth aspect of the present invention, in the displacement sensor failure control device according to the seventh aspect of the present invention, the second energization control means stops energization for holding an armature on one of the electromagnets, A configuration is adopted in which, after a predetermined period has elapsed from the stop, energization for causing the other of the electromagnets to attract the armature is started.

According to the eighth aspect of the invention, it is possible to control the energization start timing for sucking the armature without being based on the output of the displacement sensor. Therefore, even if a failure occurs in the displacement sensor, the seating speed of the armature can be reduced. Can be properly controlled.

According to a ninth aspect of the present invention, in the failure control device for a displacement sensor according to the seventh aspect of the present invention, the second energization control means detects a voltage change of one electromagnet holding the armature. The opening of the armature is determined, and after a lapse of a predetermined period from the determination of the opening of the armature, energization for causing the other of the electromagnets to attract the armature is started.

According to the ninth aspect of the present invention, it is possible to control the energization start timing for sucking the armature without being based on the output of the displacement sensor. Therefore, even if a failure occurs in the displacement sensor, the seating speed of the armature can be reduced. Can be properly controlled.

According to a tenth aspect of the present invention, in the displacement sensor failure control device according to the seventh aspect of the present invention, the second energization control means detects a current or voltage change of one of the electromagnets from which the armature is attracted. The seating of the electromagnet of the armature is determined, and in response to the seating of the armature being determined, the energization of the electromagnet is switched from the energizing for attracting the armature to the energizing for holding the armature. Take the configuration.

According to the tenth aspect, the timing of switching from the armature suction operation to the armature holding operation can be controlled without being based on the output of the displacement sensor.

According to an eleventh aspect of the present invention, in the failure control device for a displacement sensor according to the first or second aspect, the displacement sensor is provided so as to be connected to the mechanical element, and is magnetized in a displacement direction of the mechanical element. A magnet, and a magnetic sensor that detects a magnetic flux from the magnet and outputs a sensor output corresponding to the detected magnetic flux amount, and detects displacement of the mechanical element based on the magnetic sensor output. Take the configuration.

According to the eleventh aspect, breakage of the magnet,
It is possible to determine a failure of the displacement sensor due to deterioration, inclination, and the like.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings, taking an electromagnetic actuator for driving a valve of an engine as an example. FIG. 1 is a block diagram illustrating an overall configuration of an electromagnetic actuator 60 and a control device 50 that controls the electromagnetic actuator 60.
The control device 50 includes a microcomputer and circuit elements attached thereto. The control device 50 includes an input interface 51 that receives signals from various sensors,
A central processing unit 53 (hereinafter referred to as a “CPU”), a ROM 54 (read-only memory) for storing programs and data to be executed, a RAM 55 (random access memory) for providing a work area at the time of execution and storing operation results and the like; An output interface 52 for sending a control signal to each part of the engine is provided.

The input interface 51 of the control device 50
, A signal representing the displacement output from the displacement sensor 65 is input. Further, the engine speed (Ne), the engine water temperature (Tw), the intake air temperature (Ta), and the battery voltage (V
B), a signal 79 from various sensors representing an ignition switch (IGSW) and the like is input, and a desired torque detected by the required load detection means 78 is input.
The required load detection means 78 can be realized by, for example, an accelerator pedal sensor that detects the amount of depression of the accelerator pedal.

The electromagnetic actuator 60 includes the valve 20,
The armature 22, the electromagnet 63 and the displacement sensor 65 are provided. The electromagnet 63 is specifically composed of a pair of electromagnets of a valve-opening electromagnet and a valve-closing electromagnet. When the electromagnet 63 is energized, the armature 22 is driven and starts to be displaced. The valve 20 is opened and closed according to the displacement of the armature 22.

The drive circuit 77 performs pulse width modulation on the voltage supplied from the constant voltage source 75 according to a control signal from the control device 50 and supplies the voltage to the electromagnet 63 of the electromagnetic actuator 60. A current detector 71 is connected to the drive circuit 77, and the current detector 71 detects the magnitude of the current supplied to the electromagnet 63 and feeds it back to the control device 50. Further, a voltage detector 72 is connected to the drive circuit 77, and the voltage detector 72 detects the magnitude of the voltage of the electromagnet 63 and feeds it back to the control device 50.

Based on the displacement of the armature detected by the displacement sensor 65, the control device 50 preliminarily stores parameters such as the timing of power supply to the electromagnet 63, the magnitude of the voltage to be supplied, and the period for supplying the voltage to the ROM 54. Is determined in accordance with the control program stored in the control interface, and is output as a control signal via the output interface 52. When the control device 50 determines the control signal,
If necessary, the detection signals from the various sensors 79 and the required load detection means 78 are taken into consideration.

On the other hand, when a failure occurs in the displacement sensor 65, the control device 50 determines the timing and power supply of power to the electromagnet 63 based on a signal fed back from the current detector 71 and / or the voltage detector 72. Parameters such as the magnitude of the voltage to be applied and the period for supplying the voltage,
It is determined according to a control program stored in the ROM 54 in advance, and is output as a control signal via the output interface 52. When deciding the control signal, the control device 50 may use the various sensors 79 as needed.
And the detection signal from the required load detection means 78 is taken into account.

According to one embodiment of the present invention, the displacement sensor 65 includes a permanent magnet that operates in accordance with the displacement of the armature 22, and a Hall element that detects the magnetic flux density from the permanent magnet. The displacement is detected in accordance with the set Hall voltage. However, in other embodiments, the displacement sensor can be implemented in any other way. For example, a permanent magnet interlocked with the displacement of the armature 22 and a search coil that outputs an induced voltage according to a change in magnetic flux density per unit time caused by the displacement are provided, and the displacement of the armature 22 is detected from the output induced voltage. You may make it.

FIG. 2 is a sectional view showing the overall schematic structure of an electromagnetic actuator 60 on which a displacement sensor 65 according to one embodiment of the present invention is mounted. Electromagnetic actuator 60
Is composed of a valve opening / closing section 30, a driving section 31, and a displacement sensor mounting section 32. In this embodiment, the valve opening / closing unit 30, the driving unit 31, and the displacement sensor mounting unit 3
The transmission shaft 8 extending over 2 is divided into transmission shafts 8a, 8b and 8c so as to prevent swinging of the behavior of the armature and smoothly open and close the valve.

The valve opening / closing section 30 includes a valve 61 provided in an intake passage or an exhaust passage (hereinafter referred to as an intake / exhaust passage) 2 of the internal combustion engine to open and close the intake / exhaust passage 2. When the valve 61 is driven upward by the electromagnetic actuator 60, the valve 61 comes into close contact with the valve seat 7 provided in the intake / exhaust passage 2 of the engine and stops, thereby closing the intake / exhaust passage 2.
The valve 61 leaves the valve seat 7 when driven downward by the electromagnetic actuator 60, and the valve seat 7
The air intake / exhaust passage 2 is opened by descending to a position at a predetermined distance from the air inlet / outlet.

The transmission shaft 8 is connected to the valve 61 upward. The lower end of the transmission shaft 8a is a valve 61
And is held movably in the axial direction by a valve guide 9 provided on the upper wall portion of the intake / exhaust passage 2. Further, the transmission shaft 8a is urged upward by a first spring member 12 provided between a lower spring seat 10 and an upper spring seat 11 provided around the valve guide 9. Thus, the transmission shaft 8a always moves upward to the first spring member 12
Provides an urging force.

The drive section 31 has a mechanism for driving the valve 61. A solenoid-type valve-closing electromagnet 5 provided at an upper position and a solenoid-type valve-opening electromagnet 6 provided at a lower position are provided in the housing 18 made of a nonmagnetic material in the drive unit 31. The electromagnet 63 shown in FIG. 1 corresponds to the valve-closing electromagnet 5 or the valve-opening electromagnet 6. The valve-closing electromagnet 5 is surrounded by a yoke 15, and the valve-opening electromagnet 6 is surrounded by a yoke 16. Further, an armature 62 is arranged between the valve-closing electromagnet 5 and the valve-opening electromagnet 6. The armature 62 is formed of a disk-shaped magnetic metal, and is configured to move up and down by magnetic attraction of the valve-closing electromagnet 5 and the valve-opening electromagnet 6.

The transmission shaft 8b of the drive unit 31 is connected to the upper end of the transmission shaft 8a via a cap member 20, passes through the inside of the valve-opening electromagnet 6, and passes through a cylindrical guide 13 made of a non-magnetic material. It is supported so that it can move in the axial direction. The upper end of the transmission shaft 8b supports the armature 62 from below.

The lower end of the transmission shaft 8c in the drive section 31
The armature 62 is supported from above, extends upward on the extension of the transmission shaft 8b, penetrates the inside of the valve-closing electromagnet 5, and can move in the axial direction via the cylindrical guide 14 made of a nonmagnetic material. It is supported by. The upper end of the transmission shaft 8c is connected to the lower side of the spring seat 25.

Above the spring seat 25, there is an upper spring seat 17 provided via a fixing member 24. The transmission spring 8c is provided by the second spring member 19 between the lower spring seat 25 and the upper spring seat 17. Is biased downward. Thus, the transmission shaft 8
As for c, the urging force is always applied downward by the second spring member 19. Therefore, the armature 62 is vertically supported by the transmission shafts 8b and 8c by the upward biasing force of the first spring member 12 and the downward biasing force of the second spring member 19, and the valve closing electromagnet 5 and the opening When no drive current is applied to any of the valve-side electromagnets 6, the valve-closing electromagnet 5 and the valve-opening electromagnet 6
It is held in such a balance that it is in the middle between

The displacement sensor mounting section 32 includes the spring seat 25 and the sensor housing 22, in which the displacement sensor 65 according to the present invention is mounted. The spring seat 25 protrudes upward on an extension of the transmission shaft 8, and a permanent magnet 66 (not shown) is provided at the protruding portion. The sensor housing 22 includes a spring seat 25.
Is provided above the spring seat 25 so as to oppose the protruding portion, and is fixed to the inner surface of the cylindrical fixing member 24. A spring seat 17 is provided on the outer surface at the bottom of the fixing member 24. Further, the sensor housing 22 is provided with a cylindrical guide hole 23 facing downward so that a permanent magnet 66 (see FIG. 3) provided on a protruding portion of the spring seat 25 can be accommodated. On the peripheral wall of the guide hole 23, a Hall element 67 (see FIG. 3) is arranged.

When a current is supplied to the valve-closing electromagnet 5, the yoke 15 and the armature 62 of the valve-closing electromagnet are magnetized and attract each other, and the armature 62 is attracted upward. As a result, the valve 61 is driven upward by the transmission shaft 8, comes into close contact with the valve seat 7, stops, and enters a closed state. When the current supply to the valve-closing electromagnet 5 is stopped and a current is supplied to the valve-opening electromagnet 6, the yoke 16 and the armature 62 of the valve-opening electromagnet are magnetized, and a force acts to attract the armature 62 downward. The armature 62 is driven downward in combination with the potential energy of the spring, and stops in contact with the yoke 16 of the valve-opening electromagnet. As a result, the valve 61 is driven downward by the transmission shaft 8 and the valve 6
1 is open.

FIG. 3 shows an outline of an internal cross-sectional structure in which a part of the displacement sensor mounting portion 32 of the electromagnetic actuator 60 shown in FIG. 2 is enlarged. As described above, the displacement sensor mounting section 32 includes the spring seat 25 and the sensor housing 22, and the displacement sensor 65
Is attached. The displacement sensor 65 includes a permanent magnet 66 and a Hall element 67. The permanent magnet 66 is a cylindrical magnet magnetized in the direction of displacement. The portion of the spring seat 25 projecting upward has a cylindrical shape, and the permanent magnet 66 is regulated by the magnet stopper 21 and is fixed to the spring seat 25 so as not to move. The Hall element 67 is fitted on the peripheral wall of the guide hole 23 of the sensor housing 22 such that the magneto-sensitive surface faces the side surface of the permanent magnet 66. Thus, since the permanent magnet 66 is connected to the armature 62 via the spring seat 25 and the transmission shaft 8c, by detecting the displacement of the permanent magnet 66,
The displacement of the armature 62 can be detected.

The Hall element is an element that can obtain a voltage proportional to a magnetic field. That is, the voltage Vcc is applied to the Hall element 67.
When the Hall element is placed in a magnetic field H (that is, a magnetic flux density B) in a state where the current Ih is applied to the Hall element and the current Ih in the Hall element is subjected to a force, the Hall element is placed between both terminals of the Hall element. A voltage Vh is generated. The voltage Vh is represented by the following equation (1).

[0055]

Vh = Ks · Ih · Bcosθ Equation (1)

Here, Bcos θ is the x-axis component of the magnetic flux density B (that is, the direction perpendicular to the magneto-sensitive surface of the Hall element).
And represented by Bs below. Ks is a value specific to a Hall element called a Hall coefficient, and the current Ih is expressed by a voltage source Vcc.
(For example, 5 V) and a drive current determined by the input resistance value, both of which are determined according to the Hall element used. As is clear from equation (1), the Hall voltage Vh is proportional to the magnetic flux density Bs. Therefore, the Hall voltage V
By measuring h, the magnetic flux density Bs can be easily detected.

Next, the relationship between the x-axis component Bs of the magnetic flux density of the permanent magnet 66 and the displacement of the permanent magnet 66 in the y-axis direction will be described with reference to FIG. For convenience, as shown in FIG. 4A, x is set in the left-right direction with the center of the permanent magnet 66 as the origin.
Set the y axis in the vertical direction. The permanent magnet is displaced up and down along the y-axis. The upper part of the permanent magnet 66 is N
Assume that the pole is magnetized to the south pole at the bottom and the magnet length is 9 mm. Point A at a distance of 1.5 mm from the origin on the x-axis indicates the position where the Hall element 67 is arranged. The position of the Hall element 67 in the y-axis direction is
Is at the center between the valve-closing electromagnet 5 and the valve-opening electromagnet 6 in FIG. 2 (that is, a state where current is not applied to any of the valve-closing electromagnet 5 and the valve-opening electromagnet 6).
The center position of the permanent magnet 66 in the y-axis direction is
7 are arranged so as to be in the center.

FIG. 4B is a graph showing the position in the y-axis direction when the permanent magnet 66 is displaced up and down on the y-axis.
7 shows a change in magnetic flux density Bs at point A. Permanent magnet 66
Is at the position of y = 0, the magnetic fields from the N and S poles of the permanent magnet 66 cancel each other out in the x-axis direction, and the magnetic flux density Bs becomes zero. The permanent magnet 66 is magnetized as an N pole on the upper side and as a S pole on the lower side, and is displaced in the magnetized direction. Therefore, the permanent magnet 66 is displaced upward from the origin (ie, in the + direction of the y-axis). And the magnetic flux density B
s increases in a negative region (the increase here means that the value as the absolute value of the magnetic flux density Bs, that is, | Bs | increases).

When the center of the permanent magnet 66 is displaced to a position of y = + 4.5 mm, the magnetic flux density Bs has an extreme value. Conversely, when the permanent magnet 66 moves downward from the origin (that is,
Direction), the magnetic flux density Bs increases in the positive region, and when the magnetic flux density Bs is displaced to the position of y = −4.5 mm, the magnetic flux density Bs has an extreme value. Thus, the magnetic flux density Bs is within the range of -4.5 <y <4.5 corresponding to the magnet length.
It has a linear relationship to the displacement in the y-axis direction. Therefore, by calculating the magnetic flux density with the Hall element,
The displacement of the armature can be detected.

FIG. 5 is a graph showing the standard output of the displacement sensor 65 and the output when a failure occurs. The vertical axis indicates the sensor output of the displacement sensor, that is, the Hall voltage Vh, and the horizontal axis indicates the armature displacement. In the example of this figure, the armature is 7
Displacement over a range of -3.5 mm on the horizontal axis indicates the point where the armature was seated on the yoke of the valve-closing electromagnet, and +3.
5 mm indicates a position where the armature is seated on the yoke of the valve-opening electromagnet. A graph 81 shows a standard output characteristic, that is, an output characteristic when the displacement sensor is operating normally. As described above, the standard output 81 of the displacement sensor changes almost in proportion to the displacement of the armature.

The graph 82 shows the sensor output when the magnet has deteriorated. When the magnet 66 deteriorates, the generation of the magnetic flux decreases, so that the inclination of the sensor output becomes smaller than the standard output characteristic 81. However, the midpoints of the graphs 81 and 82 overlap, indicating that the position of the midpoint does not change when the magnet is deteriorated.

A graph 83 shows a case where the middle point of the armature is shifted to the valve closing side due to a mechanical factor.
4 shows a case where the center point of the armature is shifted to the valve opening side. As described above, the armature is located at the midpoint of these electromagnets when no current is applied to both the valve-closing electromagnet and the valve-opening electromagnet 6. Since the center point of the armature is shifted, the sensor outputs shown in the graphs 83 and 84 are shifted overall as compared with the standard output characteristic 81. As a result, as shown in regions 87 and 88, the displacement of the armature protrudes from the linear detection region (1.73 V to 3.27 V) originally possessed by the displacement sensor. Therefore, the displacement of the armature cannot be accurately detected.

Graph 85 (Graph 81 on the valve closing side)
Indicates a case where the magnet is tilted due to a mechanical factor or a case where the magnet is damaged. For example, if the transmission shaft or the spring seat tilts for some reason, the magnet tilts. Further, when the magnet is damaged, the distribution of the magnetic flux generated from the magnet is shifted. In such a case, as apparent from the graph 85, the standard output characteristic 8
A linear output characteristic like 1 cannot be obtained.

As described above, when the magnet is deteriorated, tilted, broken, or shifted at the midpoint, the displacement of the armature cannot be accurately detected by the displacement sensor. Note that the graph 86 shows output characteristics when the temperature of the magnet 66 changes. As is clear from the graph 86, when the temperature changes, the output gradient changes compared to the standard output characteristic 81. However, since this output change can be corrected based on the temperature for each cycle, a failure determination of the displacement sensor due to the temperature is not performed.

FIG. 6 is a detailed functional block diagram of the displacement sensor failure control device according to one embodiment of the present invention.
The displacement sensor failure control device of the present invention can be realized in the control device 50 shown in FIG. 1 or as a separate control device composed of a microcomputer and its associated circuit elements. You can also.

The first energization control section 41 executes ordinary energization control of the electromagnetic actuator. That is, the first energization control unit 41 determines the timing to start energization and the timing to stop energization to the electromagnet based on the displacement of the armature detected by the displacement sensor 65 in a situation where the displacement sensor 65 operates normally. The drive circuit 77 energizes the electromagnet in accordance with the timing determined by the first energization control unit 41. This first energization control will be described later with reference to FIG.

The electromagnetic actuator is activated when an ignition switch of the vehicle is turned on. At this time, the armature is located at the midpoint between the yoke of the valve-opening electromagnet (hereinafter, referred to as a valve-opening yoke) and the yoke of the valve-closing electromagnet (hereinafter, referred to as a valve-closing yoke). The midpoint output failure determination unit 42
The output of the displacement sensor 65 when the ignition switch is turned on is read a predetermined number of times. If the output is not within the predetermined range, it is determined that the displacement sensor has failed.

During the operation of the electromagnetic actuator, the open-side output failure judging section 43 detects the output of the displacement sensor 65 when the holding current to the valve-opening electromagnet for holding the armature in the valve-opening side yoke is stopped. Is read out a predetermined number of times, and if the output is not within the predetermined range, it is determined that the displacement sensor has failed. Alternatively, reading of the sensor output by the open-side output failure determination unit 43 may be executed at an arbitrary timing in a state where the armature is held in the valve-opening yoke.

During the operation of the electromagnetic actuator, the closing-side output failure judging section 44 detects the output of the displacement sensor 65 at the time when the supply of the holding current to the valve-closing-side electromagnet for holding the armature in the valve-closing-side yoke is stopped. Is read a predetermined number of times, and if the output is not within a predetermined range, it is determined that a failure has occurred. Alternatively, the reading of the sensor output by the closed-side output failure determination unit 44 may be performed at an arbitrary timing in a state where the armature is held in the valve-closed yoke.

The opening / closing output failure judging section 45 determines whether or not the supply of the holding current to the valve-opening electromagnet is stopped during the operation of the electromagnetic actuator (or at any time when the armature is held in the valve-opening electromagnet). Good), the output of the displacement sensor 65 is read a predetermined number of times, and a difference from a predetermined standard value for the open side output is calculated. Similarly, during the operation of the electromagnetic actuator, the opening / closing output failure determination unit 45 stops the supply of the holding current to the valve-closing-side electromagnet (or at an arbitrary timing in a state where the armature is held in the valve-closing-side electromagnet). ), The output of the displacement sensor 65 is read a predetermined number of times, and the difference between the output of the displacement sensor 65 and a standard value of a predetermined closed side output is calculated. The open / close output failure determination unit 45 determines that the displacement sensor has failed if the difference between the open output and the close output is not within a predetermined range.

The failure control unit 46 prohibits the power supply control by the first power supply control unit 41 and disables the power supply control by the second power supply control unit 47 when the failure determination units 42 to 45 determine that there is a failure. Execute. Second energization control unit 47
Determines the timing of energizing the electromagnet based on the current actually flowing through the electromagnet detected from the current detector 71 and / or the voltage detector 72 and / or the voltage actually generated in the electromagnet.

According to the second energization control unit 47, the energization start timing of the excitation current for energizing the electromagnet for attracting the armature is determined as follows. That is, in the first embodiment of the present invention, the supply of the holding current to one of the electromagnets is stopped, and after a lapse of a predetermined period from the stop of the supply of current, the supply of the excitation current to the other electromagnet is started. In the second embodiment of the present invention, the opening of the armature from the yoke of the electromagnet is determined by detecting a change in the voltage of one of the electromagnets, and after a lapse of a predetermined period from the determination of the armature opening, The energization of the exciting current to the other electromagnet is started.

According to the second energization control unit 47, switching from constant voltage control for applying a constant voltage to the electromagnet for attracting the armature to constant current control for applying a constant current to the electromagnet for holding the armature is performed. Timing is performed in response to detecting the armature sitting on the yoke of the electromagnet. The seating of the armature can be detected based on a change in a current flowing through the electromagnet and / or a voltage generated in the electromagnet. The second energization control will be described later with reference to FIGS.

FIG. 7 is a graph showing an example of a predetermined range in which a fault is determined for the midpoint output, the open side output, the closed side output, and the open / close output. A graph 91 corresponds to the graph 81 of FIG. 5, and is a standard output characteristic when the displacement sensor is operating normally. The graph 92 corresponds to the graph 82 of FIG. 5 and shows the output characteristics in which the inclination is reduced due to the deterioration of the magnet. A graph 94 corresponds to the graph 84 of FIG. 5 and shows an output characteristic in which a middle point shift occurs due to a shift of the middle point of the armature. A graph 95 (overlapping with the graph 91 on the valve-closed side) corresponds to the graph 85 in FIG. 5 and shows an output characteristic for which a linear characteristic cannot be obtained due to the inclination of the magnet (or breakage of the magnet). Graph 9
Numeral 6 corresponds to the graph 86 in FIG. 5 and shows output characteristics in which the inclination changes with the temperature of the magnet.

As for the midpoint output, when the ignition switch is turned on, the output of the displacement sensor is read five times continuously every 10 milliseconds. If all of the read five sensor outputs are not within the range of “midpoint standard value 2.500 V ± set value 0.015 V”, it is determined that the displacement sensor has failed. This ± set value 0.015V is approximately ± 50μ
m of displacement. The midpoint standard value of 2.500 V is a sensor output value corresponding to the midpoint of the armature in the standard characteristic 91.

Regarding the open side output, the sensor output of the displacement sensor is read at the timing when the supply of the holding current to the valve side electromagnet is stopped during the operation of the electromagnetic actuator. The read sensor output indicates “open standard value 1.730V−set value 0.10” for five consecutive cycles.
0V "to" open standard value 1.730V + set value 0.300
If it is not in the range of "V", it is determined that the displacement sensor has failed. The open-side standard value of 1.730 V is the displacement (+) when the armature is located at the valve-opening side yoke in the standard characteristic 91.
(3.5 mm). here,
One cycle indicates a period in which the armature is released from the valve-closing yoke, sits on the valve-opening yoke, and then sits on the valve-closing yoke and is opened again.

As for the closing side output, the output of the displacement sensor is read at the timing when the supply of the holding current to the valve closing side electromagnet is stopped during the operation of the electromagnetic actuator. The read sensor output is set to “closed standard value 3.270 V−set value 0.300 V” for five consecutive cycles.
If it is not within the range of “closed standard value 3.270 V + set value 0.100 V”, it is determined that a failure has occurred. Closed side standard value 3.2
70V is a sensor output value corresponding to the displacement (-3.5 mm) when the armature is located on the valve closing yoke in the standard characteristic 91.

Regarding the open / close output, during the operation of the electromagnetic actuator, the open-side output and the close-side output are | (open-side standard value 1.730 V-open-side output)-(close-side standard) for five consecutive cycles. Value 3.270-
(Closed side output) If |> 0.030 V, it is determined that the displacement sensor has failed.

Here, the above-mentioned five consecutive times is merely an example, and other times can be used. Further, even if they are not continuous, if five sensor outputs are not within a predetermined range, it may be determined that a failure has occurred.

As shown in the graph 92, when the magnet is deteriorated, the inclination of the sensor output becomes small, so that the failure can be determined by detecting the open side output and the closed side output. As shown in the graph 94, when a midpoint shift occurs, a failure can be determined by detecting the midpoint output when the ignition switch is turned on. If the midpoint shift occurs during the operation of the electromagnetic actuator, the open-side output or the close-side output is offset, so that the failure can be determined by detecting the open-side output and the close-side output.

Further, as shown in the graph 95, when the magnet is inclined or broken, the inclination of the sensor output does not become constant, so that the failure can be determined by detecting the open / close output. In particular, when the magnet is damaged, the open-side output and / or the close-side output is greatly offset, so that a failure can be determined from any of the open-side output, the close-side output, and the open / close output.

FIG. 8 is a flowchart executed by the midpoint output failure judging section 42 to judge the failure of the displacement sensor based on the midpoint output. This flow is executed for a predetermined period, for example, every 10 milliseconds when the ignition switch is turned on. Also, when this routine is first executed, the midpoint output fault counter is initialized to zero.

The failure flag is set to zero when the ignition switch is turned on. In this embodiment, it is assumed that the failure flag is not reset to zero during one operation cycle (one operation cycle from start to stop of the engine).

In step 101, the output is read from the displacement sensor. It is determined whether the sensor output is within a predetermined upper limit (2.515 V in the example of FIG. 8) and a predetermined lower limit (2.485 V in the example of FIG. 8) (102 and 103). If the sensor output is between the upper limit value and the lower limit value, it indicates that the sensor output is appropriate, so the process proceeds to step 107, and the midpoint output failure counter is reset to zero.

If the sensor output is larger than the upper limit value in step 102, or if the sensor output is smaller than the lower limit value in step 103, it indicates that the sensor output is not within the range between the upper limit value and the lower limit value. To increment the middle point output failure counter. In step 105, if the middle point output failure counter is larger than a predetermined value (for example, 4), it indicates that the sensor output has not been within the predetermined range five times consecutively. set. Thus, the failure of the displacement sensor is determined.

FIG. 9 is a flowchart executed by the open-side output failure determination section 43 to determine the failure of the displacement sensor based on the open-side output. This flow is executed in accordance with the end of the energization to the valve-opening electromagnet during the normal operation of the electromagnetic actuator. When this routine is first entered, the open-side output failure counter is initialized to zero.

At step 121, it is determined whether or not 1 is already set in the failure flag. If 1 is set, it is already determined that a failure has occurred, and the routine exits without further processing. If 1 is not set,
Proceeding to step 122, it is determined whether the timing of stopping the supply of the holding current to the valve-opening electromagnet has come. If it has not arrived, the routine exits as it is, and if it has arrived, the routine proceeds to step 123, where the sensor output is read from the displacement sensor. The read sensor output is stored in a memory (for example, a RAM) for use in a subsequent failure determination based on the switching output.

The sensor output is equal to the upper limit value (in the example of FIG. 8,
2.03 V) and the lower limit (1.63 in the example of FIG. 8).
V) (124 and 1)
25). If the sensor output is within this range, an appropriate sensor output is indicated, and the routine proceeds to step 126, where the open-side output failure counter is reset.

When the sensor output is larger than the upper limit or when the sensor output is smaller than the lower limit, the sensor output becomes
Since it is not within the range of the upper limit value and the lower limit value, the process proceeds to step 127, where the open-side output failure counter is incremented. Proceeding to step 128, it is determined whether the open side output fault counter is greater than a predetermined value (eg, 4). If it is larger than the predetermined value, it indicates that the open side output has not been within the predetermined range for five consecutive cycles, so the process proceeds to step 129, and 1 is set to the failure flag. Thus, the failure of the displacement sensor is determined. Step 12
If the open-side output failure counter has not reached the predetermined value in step 8, the routine exits the routine.

FIG. 10 is a flowchart executed by the closed-side output failure judging section 45 to determine the failure of the displacement sensor based on the closed-side output. This flow is executed during the normal operation of the electromagnetic actuator in accordance with the termination of the current supply to the valve-closing-side electromagnet. When this routine is first entered, the closed-side output fault counter is initialized to zero.

At step 141, it is determined whether or not 1 is already set in the failure flag. If "1" is set, it indicates that a failure has already been determined, and the routine exits as it is. If 1 is not set, the routine proceeds to step 142, where it is determined whether or not the timing to stop energizing the valve-closing-side electromagnet has come. If it has not arrived, the routine exits as it is, and if it has arrived, the process proceeds to step 143 to read the sensor output from the displacement sensor. The read sensor output is stored in a memory (for example, a RAM) for use in a subsequent failure determination based on the switching output.

The sensor output is equal to the upper limit value (in the example of FIG. 8,
3.37 V) and the lower limit (2.97 in the example of FIG. 8).
V) (144 and 1)
45). If the sensor output is within this range, an appropriate sensor output is indicated, and the routine proceeds to step 146, where the closed-side output failure counter is reset.

If the sensor output is larger than the upper limit or the sensor output is smaller than the lower limit, it indicates that the sensor output is not within the above-mentioned predetermined range.
To increment the closed-side output failure counter.
Proceeding to step 148, it is determined whether the closed side output fault counter is greater than a predetermined value (eg, 4). If it is larger than the predetermined value, it indicates that the closed-side output has not been within the predetermined range for five consecutive cycles, and the routine proceeds to step 149, where 1 is set to the failure flag. Thus, the failure of the displacement sensor is determined. If the closed-side output failure counter has not reached the predetermined value in step 148, the routine exits as it is.

FIG. 11 is a flowchart executed by the open / close output failure determination unit 45 to determine the failure of the displacement sensor using both the open side output and the close side output.
This flow is during normal operation of the electromagnetic actuator,
This is executed in accordance with the end of energization to the valve-closing-side electromagnet. When this routine is entered for the first time, the open / close output failure counter is initialized to zero.

In step 161, it is determined whether or not 1 has already been set in the failure flag. If "1" is set, it indicates that a failure has already been determined, and the routine exits as it is. If 1 has not been set, the routine proceeds to step 162, where it is determined whether one cycle has been completed. As mentioned above, one cycle is
The period in which the armature makes one reciprocation between the valve closing yoke and the valve opening yoke is shown. When one cycle is completed, FIG.
As described above with reference to FIG. 10 and FIG. 10, the open-side output and the closed-side output in the cycle stored in the memory are read (163), and for the read open-side output and closed-side output, "| It is determined whether or not the condition of “side standard value−open side output) − (closed side output−closed side standard value) |> predetermined value” is satisfied (164). Here, the predetermined value is, for example, 0.03 V as described above. If the above conditions are not satisfied, the difference between the standard value of the open side output and the standard value of the closed side output is small, indicating that the sensor output of this cycle is close to the standard characteristic. It is reset (165).

If the above condition is satisfied in step 164, the difference between the standard value of the open side output and the standard value of the closed side output is large, and the sensor output in this cycle is far from the standard characteristic. Therefore, the open / close output failure counter is incremented (166). Step 16
7 and the open / close output failure counter has a predetermined value (for example,
4) Determine if it is greater than. If it is larger than the predetermined value, it indicates that the open / close output has not been within the predetermined range for five consecutive cycles, and the routine proceeds to step 168, where 1 is set to the failure flag. Thus, the failure of the displacement sensor is determined. If the open / close output failure counter has not reached the predetermined value in step 167, the routine exits as it is.

FIG. 12 is a diagram showing a method of controlling the energization of the electromagnet based on the output of the displacement sensor, which is executed by the first energization control unit 41. A waveform 171 indicates a time waveform of the displacement of the armature detected by the displacement sensor. A waveform 172 shows a time waveform of a current flowing through the valve-opening electromagnet, and a waveform 173 shows a time waveform of a current flowing through the valve-closing electromagnet.

At time t1, the supply of the holding current to the valve-closing electromagnet is stopped. The timing of stopping the supply of the holding current is calculated based on the period T10 measured by the measurement timer in the previous cycle. Here, the period T10 is a period from when the supply of the holding current to the valve closing electromagnet is stopped to when the armature is displaced from the valve closing yoke to a point of 1 mm. The period T10 changes according to the engine speed NE and the engine load (PB, θAP (accelerator opening), etc.). Therefore, the timing of stopping the supply of the holding current to the valve-closing-side electromagnet in the current cycle is determined based on the displacement state of the armature in the previous cycle so as to conform to the current operation situation.

When the application of the holding current to the valve-closing electromagnet is stopped, the armature held by the valve-closing yoke starts displacing toward the valve-opening side. When the armature reaches the valve closing point d1 (time t2), a predetermined period T100
The operation timer in which is set is started. Here, the valve closing point d1 is a threshold value at which the armature reaches this point and is determined to be closed. Further, the period T100 is
This is a period calculated based on the period T11 measured by the measurement timer in the previous cycle. Period T1
1 indicates that the armature has a predetermined valve opening measurement start point d.
4 (for example, 6.5 mm to the valve-opening-side yoke) until it reaches the valve-opening point d6. The valve opening point d6 is a threshold value at which it is determined that the valve is opened when the armature reaches this point. The period T11 also changes according to the engine speed and the engine load. Therefore, the timing of applying the constant voltage to the valve-opening electromagnet in the current cycle is determined based on the displacement state of the armature in the previous cycle so as to conform to the current operation situation.

Thus, when the period T100 has elapsed (time t4), a predetermined constant voltage is applied to the valve-opening electromagnet, and the armature is attracted by the valve-opening electromagnet. The constant voltage application period (t4 to t6) is determined in advance by searching a map based on, for example, the current engine speed and the engine load.

After applying the constant voltage, at time t6,
It is determined whether or not the armature is seated based on the output from the displacement sensor. If the armature is seated, the operation is switched to a holding operation for supplying a constant current to the valve-opening electromagnet. At this time, an operation timer in which a predetermined period T110 is set is started. The period T110 is a period in which a large current (hereinafter, this is referred to as a catch current) is energized temporarily in order to securely seat the armature on the valve opening side, and the engine load (P
B, θAP (accelerator opening) and the like, and the rotational speed NE. After the elapse of the period T110, the holding operation by the constant current control is performed.

The holding operation is performed until the power supply stop timing (time t8) calculated based on the period T20 measured by the measurement timer in the previous cycle. Here, during the period T20, the armature is moved 1 mm from the valve-closing side yoke from the point in time when the application of the holding current to the valve-opening electromagnet is stopped.
It is the period until it is displaced to the point. The period T20 changes according to the engine speed and the engine load. Therefore, the timing of stopping the supply of the holding current to the valve-opening electromagnet in the current cycle is determined based on the displacement state of the armature in the previous cycle so as to conform to the current operation situation.

At time t8, when the application of the holding current to the valve-opening electromagnet is stopped, the armature starts to move toward the valve-closing side. When the armature reaches the valve opening point d6 (time t9), an operation timer in which a predetermined period T200 is set is started. The period T200 is a period T2 measured by the measurement timer in the previous cycle.
1 is a period calculated based on the first period. Here, the period T2
1 indicates that the armature has a predetermined valve closing measurement start point d.
3 (for example, a point 6.5 mm from the valve closing side yoke) to a valve closing point d1.
The period T21 changes according to the engine speed, the engine load, and the like. Therefore, the timing of applying a constant voltage to the valve-closing-side electromagnet in the current cycle is determined based on the state of displacement of the armature to the valve-closing side in the previous cycle so as to conform to the current operation situation.

Thus, when the period T200 has elapsed (time t10), a predetermined constant voltage is applied to the valve-closing electromagnet, and the armature is attracted by the valve-closing electromagnet. The application period of the constant voltage (t10 to t13) is determined in advance by searching a map based on, for example, the current engine speed and the engine load.

After the constant voltage is applied, at time t13, it is determined whether or not the armature is seated based on the output from the displacement sensor. At this time, an operation timer in which a predetermined period T210 is set is started. The period T210 is a period during which a catch current is applied to reliably seat the armature on the valve closing side, and includes an engine load (PB, θAP, etc.) and an engine speed NE.
It is calculated based on After the period T210 has elapsed, the holding operation by the constant current control is performed.

As described above, in the normal operation of the electromagnetic actuator, the start of energization and the energization of the electromagnet are performed based on the displacement of the armature detected from the displacement sensor and while performing feedback control so as to be adapted to the current driving situation. Calculate the stop timing.

FIG. 13 is a diagram showing a first embodiment in which the second energization control unit 47 executes energization control when the failure judgment units 42 to 45 determine that a failure has occurred.
Waveform 181 is a time waveform showing the actual displacement of the armature. A waveform 182 shows a time waveform of a current flowing through the valve-opening electromagnet, and a waveform 183 shows a time waveform of a current flowing through the valve-closing electromagnet.

As described above, when a failure is determined,
The failure control unit 46 switches from energization control based on displacement from the displacement sensor to energization control based on a change in current or / and voltage flowing through the electromagnet. According to the first embodiment, the start timing of applying a constant voltage to one electromagnet (that is, the start timing of energization) is controlled based on the timing at which the application of the holding current to the other electromagnet is stopped. The timing of switching from the constant voltage control for attracting the armature to the constant current control for holding the armature is controlled based on the timing at which the seating of the armature is detected based on a change in current or voltage flowing through the electromagnet.

At time t1, by stopping the application of the holding current to the valve-closing-side electromagnet, the armature starts displacing toward the valve-opening side. The timing of stopping the supply of the holding current to the valve-closing-side electromagnet is determined by taking into account the invalid time (the time from the end of energization to the time when the armature reaches a displacement (for example, a point of 1 mm) away from the seating position). Is determined based on Here, as the invalid time, a value measured when the displacement sensor was operating normally can be used.

At the same time as the stoppage of the holding current to the valve-closing electromagnet, the operation timer in which the period T10 is set is started.
The period T10 is measured in a cycle when the displacement sensor is operating normally, that is, when energization of the electromagnet is controlled by the first energization control unit 41, as described with reference to FIG. The period from when the holding current to the valve-closing electromagnet is stopped to when the armature is displaced to a point 1 mm from the valve-closing yoke. At time t2 when the period T10 has elapsed, the application of the constant voltage to the valve-opening electromagnet is started. As described above, the constant voltage application period (t2 to t3) is determined in advance by searching a map based on, for example, the current engine speed and engine load.

At time t3, it is determined whether the armature is seated on the valve-opening yoke. The determination of seating can be made by any method. For example, when the armature is seated, the impedance of the electromagnet on the seated side temporarily increases, so switching to the constant current control is performed at time t3. If the period during which the voltage value of the electromagnet is higher than the predetermined value is equal to or longer than the predetermined period, It is determined that the driver has been seated. Or
When the armature approaches the electromagnet to be seated, the magnetic flux rapidly increases, so that a temporary “dent” appears in the current flowing through the electromagnet. Therefore, the seating may be determined by detecting the depression.

If it is determined that the user is seated, an operation timer in which a period T11 is set is started, and over the period T11,
A large catch current is applied to the electromagnet temporarily. Thus, the armature is securely seated. The period T11 is a period measured in a cycle when the displacement sensor is operating normally, as described with reference to FIG. 12, and the armature is set at the predetermined valve opening measurement start point d4.
Is reached until the valve opening point d6 is reached. When the period T11 has elapsed, the operation shifts to a holding operation by constant current control.

The same energization control is performed in the valve closing operation. That is, at time t5, the armature starts displacing to the valve closing side by stopping the supply of the holding current to the valve opening side electromagnet. The timing of stopping the supply of the holding current to the valve-opening electromagnet is determined based on the timing of stopping the supply of electricity in consideration of the invalid time. Here, as the invalid time, a value measured when the displacement sensor was operating normally can be used.

At the same time as the stoppage of the holding current to the valve-opening electromagnet, the operation timer in which the period T20 is set is started. The period T20 is, as described with reference to FIG.
This is the period measured in the cycle when the displacement sensor is operating normally, from the time when the holding current to the valve-opening electromagnet is stopped to the time when the armature is displaced to a point 1 mm from the valve-closing yoke. Is shown. Period T20
At the time point t6 when the time has elapsed, the application of the constant voltage to the valve-closing-side electromagnet is started. The application period of the constant voltage (t6 to t7)
As described above, for example, it is determined in advance by searching a map based on the current engine speed and the engine load.

At time t7, it is determined whether the armature has been seated on the valve closing yoke. The determination of seating can be made in the same manner as described above. If it is determined that the user is seated, an operation timer for which the period T21 is set is started, and a large catch current is temporarily supplied to the valve-closing electromagnet over the period T21. Thus, the armature is securely seated. The period T21 is a period measured in a cycle when the displacement sensor is operating normally, as described with reference to FIG. 12, and the armature reaches the predetermined valve closing measurement start point d3. After that, it is a period until reaching the valve closing point d1. When the period T21 has elapsed, the operation shifts to a holding operation by constant current control.

FIG. 14 is a diagram showing a second embodiment in which the second energization control section executes the energization control when the failure judgment sections 42 to 45 determine that a failure has occurred. Waveform 181 is a time waveform showing the actual displacement of the armature. A waveform 184 shows a time waveform of a current flowing through the valve-opening electromagnet, and a waveform 185 shows a time waveform of a voltage of the valve-opening electromagnet. A waveform 186 shows a time waveform of a current flowing through the valve closing electromagnet, and a waveform 187 shows a time waveform of a voltage of the valve closing electromagnet.

The difference between the second embodiment and the first embodiment is that the start timing of applying a constant voltage to one electromagnet is different from that of the first embodiment.
The control is based not on the timing of stopping the supply of the holding current to the other electromagnet but on the time of opening the armature from the other electromagnet. The opening of the armature can be performed in any manner. In this embodiment, the opening of the armature is determined based on the voltage change of the electromagnet.

At time t1, the supply of the holding current to the valve-closing electromagnet is stopped. The timing for stopping the supply of the holding current to the valve-closing electromagnet is determined based on the timing for stopping the supply of current in consideration of the invalid time. Here, as the invalid time, a value measured when the displacement sensor was operating normally can be used. When energization stops, reference number 1
As indicated by 91, a back electromotive force is generated in the valve closing electromagnet. Thereafter, when the armature starts displacing toward the valve-opening yoke by the force of the spring, the magnetic flux generated in the gap between the armature and the valve-closing-side yoke changes due to the displacement of the armature. Occurs. As a result, the voltage value lowered to the negative side due to the stop of the power supply changes toward the positive side due to the back electromotive force (reference numeral 192). Therefore, opening of the armature can be determined by detecting this voltage change.

In response to the determination that the armature is released at time t11, the operation timer in which the period T10 is set is started. As described above, the period T10 is a period measured in a cycle when the displacement sensor is operating normally, and from the time when the supply of the holding current to the valve-closing side electromagnet is stopped, the armature is closed. 1 from York
It shows a period until it is displaced to the point of mm. At a time point t2 when the period T10 has elapsed, the application of a constant voltage to the valve-opening electromagnet is started. As described above, the constant voltage application period (t2 to t3) is determined in advance by searching a map based on, for example, the current engine speed and engine load.

At time t3, it is determined whether the armature is seated on the valve-opening yoke in the same manner as described with reference to FIG. If you are determined to be seated,
The operation timer in which the period T11 is set is started, and the period T1 is started.
For one, a large catch current is temporarily supplied to the electromagnet. Thus, the armature is securely seated. The period T11 is a period measured in a cycle when the displacement sensor is operating normally, as described with reference to FIG. 12, and the armature reaches the predetermined valve opening measurement start point d3. This is a period from when the valve opening point d6 is reached. When the period T11 has elapsed, the operation shifts to a holding operation by constant current control.

The same energization control is performed in the valve closing operation. That is, at time t5, when the application of the holding current to the valve-opening electromagnet is stopped, a back electromotive force is generated in the valve-opening electromagnet. The armature starts to be displaced toward the valve closing yoke by the force of the spring. Since the magnetic flux generated in the gap between the armature and the valve-opening side yoke changes, back electromotive force is generated accordingly. As a result, the voltage value lowered to the negative side due to the stop of the power supply changes toward the positive side due to the back electromotive force. By detecting this voltage change, the opening of the armature is determined.

In response to the determination that the armature is released at time t55, the operation timer in which the period T20 is set is started. As described above, the period T20 is a period measured in a cycle when the displacement sensor is operating normally, and from the time when the supply of the holding current to the valve-opening electromagnet is stopped, the armature is closed. 1 from York
It shows a period until it is displaced to the point of mm. At a time point t6 when the period T20 has elapsed, application of a constant voltage to the valve-closing-side electromagnet is started. The application period of the constant voltage (t6 to t7)
As described above, for example, it is determined in advance by searching a map based on the current engine speed and the engine load.

At time t7, it is determined whether or not the armature has been seated on the valve closing yoke in the same manner as described with reference to FIG. If it is determined that the user is seated, an operation timer in which the period T21 is set is started, and a large catch current is temporarily supplied to the valve-closing-side electromagnet over the period T21. Thus, the armature is securely seated. The period T21 is a period measured in a cycle when the displacement sensor is operating normally, as described with reference to FIG. 12, and the armature reaches the predetermined valve closing measurement start point d3. And then close the valve d1
Until it reaches. When the period T21 has elapsed, the operation shifts to a holding operation by constant current control.

FIG. 15 is a flowchart showing the energization control at the time of failure determination according to the first embodiment of the present invention, described with reference to FIG. For simplicity, the flow of FIG. 15 shows a part of the valve opening operation at times t1 to t4 in FIG. However, the same flow is applied to the valve closing operation at the times t5 to t8. This flow is repeatedly executed at intervals of, for example, 100 milliseconds.

In step 201, it is determined whether or not the timing of stopping the supply of the holding current to the electromagnet (time t1 in FIG. 13) has arrived. When the power supply stop timing comes, the supply of the holding current to the valve-closing electromagnet is stopped, and at the same time, an operation timer in which the period T10 is set is started (211). The next time this routine is entered, the period T
It is determined whether 10 has elapsed. When the period T10 has elapsed, a constant voltage is applied to the valve-opening electromagnet for a predetermined period (time t2 to t3) (212), and the armature is attracted.

Next, when entering this routine, it is determined whether or not the armature is seated on the valve opening side yoke (20).
3). If it is determined that the armature is seated, the period T
At the same time as when the operation timer 11 is started, a catch current is supplied to the valve-opening electromagnet (213). Thus, the armature is securely seated on the valve-opening yoke. Next, when entering this routine, it is determined whether or not the period T11 has elapsed. When the period T11 has elapsed, a holding current is supplied to the valve-opening electromagnet (214), and the armature is held.

FIG. 16 is a flowchart showing the energization control at the time of failure determination according to the second embodiment of the present invention, described with reference to FIG. For simplicity, the flow of FIG. 16 shows a part of the valve opening operation at times t1 to t4 in FIG. However, the same flow is applied to the valve closing operation at the times t5 to t8. This flow is also repeatedly executed at intervals of, for example, 100 milliseconds.

In step 301, it is determined whether or not the timing of stopping the supply of the holding current to the electromagnet (time t1) has come. When the time t1 has come, the supply of the holding current to the valve-closing-side electromagnet is stopped (311). Next, when the routine is entered, it is determined in step 302 whether the armature has been released from the valve opening side yoke (302). If the armature is released, the period T10
Then, the operation timer in which is set is started (312). Next, when entering this routine, it is determined whether or not the period T10 has elapsed (303). When the period T10 has elapsed, a constant voltage is applied to the valve-opening electromagnet for a predetermined period (time t2 to t3) (313), and the armature is attracted.

Next, when entering this routine, it is determined whether or not the armature is seated (304). If it is determined that the armature is seated, the operation timer in which the period T11 is set is started, and at the same time, a catch current is supplied to the valve-opening electromagnet (314). Thus, the armature is securely seated on the valve-opening yoke. Next, when entering this routine, it is determined whether or not the period T11 has elapsed.
When the period T11 has elapsed, a holding current is supplied to the valve-opening electromagnet (316), and the armature is held.

When the displacement of the armature cannot be detected by the displacement sensor, the driving of the electromagnetic actuator can be controlled based on the change in the current and / or the voltage flowing through the electromagnet. Self-propelled is possible even when the occurrence of

[0131]

According to the present invention, since the output of the displacement sensor is inspected at a predetermined timing, a failure of the displacement sensor can be found early and surely. Further, according to the present invention, even when it is determined that the displacement sensor has failed, the operation of the engine can be continued.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire electromagnetic actuator and its control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a mechanical structure of an electromagnetic actuator according to one embodiment of the present invention.

FIG. 3 is a diagram showing a mechanical structure of a displacement sensor according to one embodiment of the present invention.

FIG. 4 shows (a) a permanent magnet according to an embodiment of the present invention;
And (b) is a diagram showing the relationship between the displacement of the permanent magnet and the magnetic flux density.

FIG. 5 is a graph showing an output characteristic of the displacement sensor in a normal state and an output characteristic of a displacement sensor in a failure in one embodiment of the present invention.

FIG. 6 is a functional block diagram of a displacement sensor failure control device according to an embodiment of the present invention.

FIG. 7 is a graph showing an example of a predetermined range set based on a middle point output, an open side output, a close side output, and an open / close output of a sensor output in one embodiment of the present invention.

FIG. 8 is a flowchart illustrating a method for determining a failure of a displacement sensor based on a midpoint output of a sensor output according to an embodiment of the present invention.

FIG. 9 is a flowchart illustrating a method of determining a failure of a displacement sensor based on an open output of a sensor output according to an embodiment of the present invention.

FIG. 10 is a flowchart illustrating a method of determining a failure of a displacement sensor based on a closed output of a sensor output according to an embodiment of the present invention.

FIG. 11 is a flowchart illustrating a method for determining a failure of a displacement sensor based on an open / close output of a sensor output according to an embodiment of the present invention.

FIG. 12 is a diagram showing a method for controlling energization of an electromagnet based on an output from a displacement sensor in one embodiment of the present invention.

FIG. 13 is a diagram showing a method for controlling energization of the electromagnet based on changes in the current value and the voltage value of the electromagnet when it is determined that the displacement sensor has failed in one embodiment of the present invention.

FIG. 14 is a diagram showing a method for controlling energization of the electromagnet based on changes in the current value and the voltage value of the electromagnet when it is determined that the displacement sensor has failed in another embodiment of the present invention.

FIG. 15 is a flowchart illustrating a method for controlling energization based on changes in the current value and voltage value of the electromagnet when it is determined that the displacement sensor has failed in one embodiment of the present invention.

FIG. 16 is a flowchart showing a method for controlling energization based on changes in the current value and voltage value of an electromagnet when a displacement sensor is determined to be faulty in another embodiment of the present invention.

[Explanation of symbols]

41 first energization control unit 42 to 45 failure determination unit 46 failure control unit 47 second
Energization control section 65 displacement sensor 77 drive circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/22 320 F02D 41/22 320 G01B 7/00 G01B 7/00 Z (72) Inventor Hidetaka Ozawa Saitama 1-4-1, Chuo, Wako, F-term F-term in Honda R & D Co., Ltd. (Reference) 2F063 AA02 BA06 CA02 CB01 DA01 DA05 DD02 GA52 KA04 KA05 LA15 LA23 3G018 AB08 AB16 BA38 CA12 DA66 EA02 EA17 EA21 EA22 EA24 FA01 FA06 FA07 GA39 3G092 AA01 AA11 DA01 DA02 DA07 DF05 DG09 EA11 3G301 HA01 HA19 JA13 JA20 JB01 JB08 JB09 JB10 LA07 LC01 LC10 NA08 NB06 NB11 NB20 NE17 NE19 PE01Z PE08Z PF16Z PG02Z 5H540 AA10 BA10 BB06 BB09 CC09

Claims (11)

[Claims] 1. A displaceable mechanical element, a displacement sensor for detecting a displacement of the mechanical element, and an output from the displacement sensor at a predetermined timing within a predetermined range set based on the predetermined timing. A failure determination unit that determines that a failure has occurred in the displacement sensor when there is no failure sensor. 2. A pair of springs working in opposite directions, an armature coupled to said spring and coupled to said mechanical element in a non-operating state and supported in a neutral position provided by said spring.
And an electromagnetic actuator having a pair of electromagnets for displacing the armature between two terminal positions, wherein the displacement sensor detects displacement of the armature by detecting displacement of the armature. Control device for displacement sensor. 3. The displacement control device according to claim 2, wherein the predetermined timing includes a timing at which the electromagnetic actuator is activated, and the predetermined range is set based on a neutral position of the armature. . 4. The predetermined timing includes a timing at which an armature held by one of the pair of electromagnets is opened, and the predetermined range is set based on a predetermined standard value. 7. The actuator control device according to claim 1. 5. The predetermined timing includes a timing at which an armature held by one of the pair of electromagnets is opened and a timing at which an armature held by the other of the pair of electromagnets is opened, Is set based on a predetermined standard value for the timing at which the armature held on one of the electromagnets is opened, and based on a predetermined standard value for the timing at which the armature held on the other of the electromagnets is opened. Claim 2
4. The failure sensor for a displacement sensor according to claim 1. 6. The displacement according to claim 4, wherein the standard value is predetermined based on a sensor output detected at the predetermined timing when the displacement sensor is operating normally. Sensor failure control device. 7. A first energization control means for controlling energization of the electromagnet based on an output from the displacement sensor, and a power supply to the electromagnet based on a change in one or both of current and voltage of the electromagnet. A second energization control unit for controlling energization, wherein if the failure determination unit determines that a failure has occurred, the energization control by the first energization control unit is prohibited, and the second energization control unit The failure control device for a displacement sensor according to claim 2, further comprising a failure control unit configured to execute the energization control. 8. The second energization control means stops the energization for holding the armature on one of the electromagnets and, after a predetermined period from the energization stop, causes the other of the electromagnets to attract the armature. The failure sensor for a displacement sensor according to claim 7, wherein energization is started. 9. The second energization control means determines the opening of the armature by detecting a voltage change of one of the electromagnets holding the armature, and determines whether the armature has been opened for a predetermined period of time. The failure sensor for a displacement sensor according to claim 7, wherein after the lapse of time, energization for causing the other of the electromagnets to attract the armature is started. 10. The second energization control means determines whether the armature is seated on the electromagnet by detecting a change in current or voltage of one of the electromagnets from which the armature is attracted, and determines whether the armature is seated on the electromagnet. 8. The electromagnetic actuator control device according to claim 7, wherein, in response to the determination, energization of the electromagnet is switched from energization for attracting the armature to energization for holding the armature. 11. The displacement sensor is connected to the machine element, and detects a magnet magnetized in a displacement direction of the machine element and a magnetic flux from the magnet, and detects a magnet according to the detected magnetic flux amount. The failure control device for a displacement sensor according to claim 1, further comprising: a magnetic sensor that outputs a sensor output; and detecting a displacement of the mechanical element based on the magnetic sensor output.