JP3767015B2 - Abnormality detection method for electromagnetically driven valve for intake and exhaust - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetically driven valve used as an intake / exhaust valve of an internal combustion engine, and more particularly, to an abnormality detection method for such an electromagnetically driven valve.
[0002]
[Prior art]
Conventionally, an intake / exhaust valve of an internal combustion engine is generally opened and closed by a camshaft driven based on rotation of a crankshaft. From the viewpoint of improving the performance of the internal combustion engine, various variable mechanisms of the valve operating system are being put into practical use in order to achieve the optimum valve opening / closing timing according to the operating state. Continuously variable types have been developed, including those of the OFF control type. These variable mechanisms include those that shift the rotational phase of the cam shaft and those that include a plurality of cam profiles on the cam shaft.
[0003]
However, in the intake / exhaust valve driven by the cam shaft as described above, it is impossible to independently and arbitrarily set all of the valve lift (valve lift), the valve opening period, and the valve opening / closing timing. Therefore, in recent years, in order to meet the demand for higher performance for internal combustion engines, research on electromagnetically driven valve systems that can set these parameters to ideal values according to operating conditions has become active. Yes.
[0004]
For example, JP-A-61-250309 discloses that a valve body supported in a neutral position by a biasing force of a pair of springs is fully opened from the neutral position by applying an electromagnetic force to a plunger connected to the valve body. The present invention relates to an electromagnetically driven valve having a structure that moves in a direction or a fully closed direction, and particularly discloses an abnormality detection method thereof. The abnormality detection method monitors the change in the current flowing through the coil when power is supplied to the electromagnetically driven valve, and when a decrease in current is observed in a certain period, it is determined that the valve is operating normally. When no decrease is observed, it is determined that there is an abnormality in the valve operation.
[0005]
[Problems to be solved by the invention]
The reason why such a decrease in current occurs is as follows. That is, the magnetic flux, that is, the circuit inductance, is inversely proportional to the square of the distance between the plunger and the core of the electromagnet, and theoretically increases abruptly immediately before the plunger collides with the core. As the magnetic flux increases, the back electromotive force e is expressed by the following equation:
e = −dΨ / dt = −N (dΦ / dt) = − L (di / dt)
Ψ = NΦ
Where Ψ: magnetic flux linkage number, Φ: magnetic flux, N: number of turns,
L: Inductance, i: Current, t: Increasing with time, the power supply voltage is almost offset by this back electromotive force, and is hardly used for current flow, and the current decreases.
[0006]
However, this phenomenon does not always occur. For example, depending on the hardware configuration including material, shape, etc., magnetic flux saturation may occur at an early stage, but in that case, even if the plunger is normally attracted to the core, the current is reduced. There may be no reduction. In addition, there is a case where control is performed to reduce the current before the plunger comes closest to the core so as to avoid collision between the plunger and the core so that adsorption is performed gently. In such a case, there is a possibility that such a decrease in current does not occur.
[0007]
In view of this situation, an object of the present invention is to provide an abnormality detection method with improved accuracy in the electromagnetically driven valve for intake and exhaust compared with the prior art.
[0008]
[Means for Solving the Problems]
An abnormality detection method for an electromagnetically driven valve for intake / exhaust according to the first invention of the present application, which has been devised to achieve the above object, is characterized in that a valve body is elastically supported at a neutral position by a biasing force of an elastic body, and a coil Inlet / exhaust electromagnetic drive configured to control the movement of the valve body by the electromagnetic force generated by controlling the current flowing through the valve to a predetermined current value acting on the plunger integrated with the valve body An abnormality detection method for a valve, characterized in that an abnormality is determined when a power supply power obtained from a voltage and a current of a power supply that supplies power to an electromagnetically driven valve is below a predetermined reference value at a predetermined time. .
[0009]
In addition, the abnormality detection method for the intake / exhaust electromagnetically driven valve according to the second invention is such that the valve body is elastically supported at the neutral position by the biasing force of the elastic body, and the current flowing through the coil has a predetermined current value. An electromagnetic detection valve abnormality detection method for an intake / exhaust valve configured such that movement control of the valve body is performed by the electromagnetic force generated by being controlled on the plunger integrated with the valve body. Integrated amount of power supply power obtained from the voltage and current of the power supply that supplies power to the electromagnetically driven valve within a predetermined period including the period during which the body moves from the fully open position to the fully closed position or from the fully closed position to the fully open position Is determined to be abnormal when the value is equal to or less than a predetermined reference value.
[0010]
Further, according to a third aspect, in the method according to the first or second aspect, the predetermined reference value is changed according to an operating state.
[0011]
As described above, the current flowing through the coil has a problem that its value varies due to hardware configuration, seating control, and the like. In the abnormality detection method according to the first aspect of the present invention configured as described above, normality or abnormality regarding the electromagnetically driven valve operation is determined based on the power supplied from the power source, so there is no such problem. In the abnormality detection method according to the second aspect of the present invention, normality or abnormality regarding the electromagnetically driven valve operation is determined based on the amount of power supplied over a certain period, that is, based on an integrated value in a certain period of supply power. Therefore, misjudgment is prevented. Further, although the command current value to the coil changes according to the operating state, in the abnormality detection method according to the third invention, the determination reference value is changed according to the operating state, so that the detection accuracy is improved. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1 is a longitudinal sectional view showing an electromagnetically driven valve for intake and exhaust according to an embodiment of the present invention. A valve body 10 shown in FIG. 1 includes a valve head (also referred to as a valve head or “valve head”) 12 and a valve shaft 14, and a valve face 13 of the valve head 12 is an internal combustion engine. The intake / exhaust port 32 is opened and closed by being seated on or separated from a valve seat 33 (valve seat) 33 provided in the intake / exhaust port 32 of the engine. The valve shaft 14 of the valve body 10 is held by a valve guide 31 so as to be slidable in the axial direction. A plunger 16 is fixed to the valve shaft 14.
[0014]
The plunger 16 is a disk-shaped member made of a soft magnetic material. An upper core 22 is disposed above the plunger 16 by a predetermined distance, and a lower core 23 is similarly disposed below the plunger 16 by a predetermined distance. Yes. The upper core 22 and the lower core 23 are made of a soft magnetic material, and are held in a predetermined positional relationship by a case 20 made of a nonmagnetic material. Further, an upper coil 24 is gripped by the upper core 22, and a lower coil 25 is gripped by the lower core 23.
[0015]
The valve shaft 14 is elastically supported in the axial direction by an upper spring 26 and a lower spring 27. The balance between the upper spring 26 and the lower spring 27 is such that the position (neutral position) of the plunger 16 when the upper coil 24 and the lower coil 25 are not energized is an intermediate position between the upper core 22 and the lower core 23. It has been. When the plunger 16 is in the neutral position, the valve element 10 takes an intermediate position between the fully open side displacement end and the fully closed side displacement end.
[0016]
According to such a configuration, a magnetic circuit including the upper core 22, the plunger 16, and the air gap formed therebetween is formed around the upper coil 24. Therefore, when a current is passed through the upper coil 24, the magnetic flux flows back through the magnetic circuit, and an electromagnetic force is generated in a direction that reduces the air gap, that is, a direction that displaces the plunger 16 upward. On the other hand, a magnetic circuit including the lower core 23, the plunger 16, and an air gap formed therebetween is formed around the lower coil 25. Accordingly, when a current is passed through the lower coil 25, an electromagnetic force is generated in a direction that causes the plunger 16 to be displaced downward from the same principle. Thus, by alternately supplying current to the upper coil 24 and the lower coil 25, the plunger 16 can be reciprocated up and down, that is, the valve body 10 can be driven alternately in the opening and closing direction.
[0017]
FIG. 2 is a circuit diagram showing a configuration example of a circuit for driving the electromagnetically driven valve shown in FIG. As shown in the figure, since the portion related to the upper coil 24 and the portion related to the lower coil 25 have the same circuit configuration, only the portion related to the upper coil 24 will be described.
[0018]
Connected to the first terminal 24a of the upper coil 24 are an emitter terminal of a forward switching element 40 and a collector terminal of a reverse switching element 41 made of an NPN transistor. In addition, the collector terminal of the forward switching element 42 and the emitter terminal of the reverse switching element 43, which are similarly formed of NPN transistors, are connected to the second terminal 24b of the upper coil 24.
[0019]
The collector terminal of the forward switching element 40 and the collector terminal of the reverse switching element 43 are both connected to the positive terminal of the power supply 50. Further, the emitter terminal of the reverse switching element 41 and the emitter terminal of the forward switching element 42 are both connected to the negative terminal of the power supply 50 via the power supply current detection circuit 51. Furthermore, the base terminals of the forward switching elements 40 and 42 are both connected to the forward output terminal 47f of the switching element drive circuit 47, and the base terminals of the reverse switching elements 41 and 43 are both switched to the switching element drive circuit 47. Are connected to the reverse output terminal 47r.
[0020]
The actual current Im flowing through the upper coil 24 is detected by the coil current detection circuit 45, and the output signal of the coil current detection circuit 45 is supplied to the current feedback circuit 46. The current feedback circuit 46 is a circuit for feeding back the value of the actual current Im flowing through the upper coil 24 to the output terminal of the switching element drive circuit 47, and the output signal of the current feedback circuit 46 is input to the − terminal of the subtraction circuit 48. Has been. The coil command current value Ic output from the engine electronic control unit (engine ECU) 60 is input to the + terminal of the subtraction circuit 48. Then, the output Ic−Im of the subtraction circuit 48 is supplied to the switching element drive circuit 47.
[0021]
The switching element driving circuit 47 includes therein a triangular wave oscillation circuit that generates a triangular wave having a predetermined period, and a comparison circuit that compares the triangular wave and the input signal Ic-Im, and the magnitude of the input signal Ic-Im. A PWM pulse signal adjusted to a duty ratio corresponding to is generated. When Ic-Im is a positive value, the switching element drive circuit 47 outputs a PWM pulse signal having a duty corresponding to the magnitude from the forward output terminal 47f, whereas when Ic-Im is a negative value, A PWM pulse signal having a duty corresponding to the magnitude is output from the reverse output terminal 47r.
[0022]
Therefore, when the input signal Ic-Im has a positive value, the two forward switching elements 40 and 42 are turned on with a duty ratio corresponding to Ic-Im, and when the input signal Ic-Im has a negative value. The two reverse switching elements 41 and 43 are turned on with a duty ratio corresponding to Ic-Im. At this time, the forward switching elements 40 and 42 and the reverse switching elements 41 and 43 are not simultaneously turned on. Thus, since the control is performed so that Ic−Im becomes 0 by the switching element driving circuit 47, the actual current Im flowing through the upper coil 24 can be made to coincide with the command current value Ic with high accuracy, and fluctuations in the power supply voltage and circuit A stable characteristic can be obtained with respect to the fluctuation of the characteristic.
[0023]
The drive circuit further includes a power supply current detection circuit 51 and a power supply voltage detection circuit 52 in order to calculate power supply power used in an electromagnetic drive valve abnormality detection process described later. As shown in FIG. 2, the power supply current detection circuit 51 is connected in series with the power supply 50, and the power supply voltage detection circuit 52 is connected in parallel.
[0024]
A plurality of curves indicated by solid lines in FIG. 3 indicate the relationship between the position of the plunger 16 (the position in contact with the upper core 22 is zero) and the electromagnetic force (attraction force) exerted on the plunger 16 by the electromagnet related to the upper core 22. The current value flowing through 24 is represented as a parameter. As shown in these curves, the electromagnetic force (attraction force) acting on the plunger increases rapidly as the valve body 10 approaches the fully closed displacement end. On the other hand, the straight line indicated by the broken line in FIG. 3 represents the relationship between the position of the plunger 16 and the urging force (lower core 23 side) exerted on the valve body 10 by the upper spring 26 and the lower spring 27. As can be seen from this straight line, the urging force only increases linearly even when the valve element 10 is close to the fully closed displacement end. Similarly, the electromagnetic force generated by the electromagnets related to the lower core 23 is also shown in FIG. 3, and the fully closed position is simply changed to the fully open position. Therefore, the closer to the fully open position or the fully closed position, the more the electromagnetic force that exceeds the biasing force can be obtained with a smaller current compared to the neutral position. Next, an electromagnetic valve driving method considering such characteristics of electromagnetic force and biasing force will be described.
[0025]
FIG. 4 is a time chart showing the valve lift (A), the upper coil command current (B), and the lower coil command current (C). In the fully closed state, as shown in FIG. 5B, a current (hereinafter, referred to as a holding current) necessary for attracting and holding the plunger 16 to the upper core 22 is passed through the upper coil 24. When opening the valve, first, the supply of the holding current is stopped. Then, the valve body 10 moves in the fully open direction by a single vibration (free vibration) of the spring mass system, but due to friction loss between the valve shaft 14 and the valve guide 31, internal friction loss of the spring itself, or the like. Since the amplitude of the valve body 10 is attenuated with respect to the ideal state, a current is supplied to the lower coil 25 at a certain timing. The current can be divided into three, an attraction current, a transition current, and a holding current, as shown in FIG.
[0026]
That is, first, an attraction current for moving the plunger 16 is passed. Next, in consideration of the characteristics of FIG. 3 described above, a transition current that decreases at a certain rate of change is applied so that the plunger 16 is attracted in a state where the electromagnetic force (attraction force) is weakened. And after adsorption | suction of the plunger 16, the electric current required for adsorption | suction holding | maintenance of the valve body 10, ie, holding current, is supplied. Similarly, when the valve is to be closed from the fully open state, the supply of the holding current to the lower coil 25 is first stopped, and the suction current, the transition current, and the holding current are sequentially supplied to the upper coil 24. As described above, the intake / exhaust electromagnetically driven valve according to the present embodiment is configured such that the current value is decreased immediately before the valve body reaches the fully open position or the fully closed position.
[0027]
Hereinafter, the abnormality detection method for an electromagnetically driven valve according to the present invention will be described in detail. The impedance Z in the LR series circuit is
Z = (R ² + (ωL) ² ) ^1/2
Here, R: Coil resistance ω: Angular frequency L: Coil inductance In the above equation, R and ω do not differ between the normal operation and abnormal operation of the valve, but L is different between normal operation and abnormal operation of the valve, and becomes a small value during abnormal operation. As a result, since the impedance Z is also a small value, the power consumption is small in order to pass the same current. In the present invention, according to such knowledge, the normality / abnormality of the operation of the electromagnetically driven valve is determined by monitoring the power supplied from the power source.
[0028]
FIG. 5 is a diagram in the case where the control shown in FIG. 4 described above is performed, and shows the current related to the coil from which the valve body is moved, the current related to the coil to which the valve body is moved, and the valve lift. It is a time chart shown about (A) normal time and (B) step-out (abnormality). The coil command current Ic (solid line) output from the engine ECU 60, the coil actual current Im (dotted line) detected by the coil current detection circuit 45, and the power supply detected by the power supply current detection circuit 51 as the current related to the coil The supply current Is (dashed line) is shown.
[0029]
As shown in the figure, at the time of step-out as compared with the normal time, the coil actual current Im on the side to which the valve body is moved, that is, the side that attracts the valve body becomes large because the inductance is small, and the command current Ic is earlier. Matches. Therefore, the current Is supplied from the power source for setting Ic-Im to 0 is smaller than that at the normal time, and a difference between the normal time and the step-out time appears particularly near the time t ₁ . In the first embodiment of the present invention, instantaneous power supplied from a power source is calculated at a crank angle a ₁ corresponding to time t ₁ and abnormality detection of an electromagnetically driven valve is performed based on the calculated value. is there.
[0030]
FIG. 6 is a flowchart showing a processing procedure of an electromagnetically driven valve abnormality detection routine according to the first embodiment. This routine is configured to be executed at every predetermined crank angle. First, at step 102, it is determined whether or not the current crank angle CA is a ₁ described above. When CA = a ₁ , the routine proceeds to step 104, and when CA ≠ a ₁ , this routine is terminated. In step 104, the power supply current Is is detected based on the output of the power supply current detection circuit 51, and the power supply voltage Vs is detected based on the output of the power supply voltage detection circuit 52. Next, at step 106, the power supply power (instantaneous power) Ps is obtained by executing the calculation Ps ← Is × Vs.
[0031]
Next, at step 108, a reference value Pref corresponding to the intake air amount GN per engine revolution (calculated separately) is obtained by referring to a map as shown in FIG. Next, in step 110, it is determined whether or not the power supply power Ps is equal to or less than the determination reference value Pref. When Ps> Pref, the routine is regarded as being in normal operation, and when Ps ≦ Pref, abnormal operation is in progress. And proceed to step 112. In step 112, abnormality countermeasure processing such as restart of the electromagnetically driven valve is executed.
[0032]
Next, a second embodiment will be described. In the first embodiment, the instantaneous power at a predetermined time is observed. However, the power supply is monitored over a specific period in which a difference in power supply between the power source and the normal state occurs. If an integral value of those monitor values is obtained and abnormality is detected, more accurate processing can be expected without erroneous detection. In the second embodiment, the power supply power is integrated in the period from time t ₀ to time t ₂ in FIG. 5, and the abnormality of the electromagnetically driven valve is detected based on the integrated power amount (corresponding to energy). It is something to try.
[0033]
FIG. 8 is a flowchart showing a processing procedure of an electromagnetically driven valve abnormality detection routine according to the second embodiment. This routine is configured to be executed at every predetermined crank angle. First, in step 202, it is determined whether or not the current crank angle CA is in the crank angle range a ₀ ≦ CA ≦ a ₂ corresponding to the above-described time t ₀ to time t _2. Sometimes the routine proceeds to step 204, and when it is not within the range, the routine is terminated. In step 204, the power supply current Is is detected based on the output of the power supply current detection circuit 51, and the power supply voltage Vs is detected based on the output of the power supply voltage detection circuit 52. Next, in step 206, the power supply power integration amount Es is updated by executing a calculation of Es ← Es + Is × Vs.
[0034]
Next, at step 208, it is determined whether or not the current crank angle CA is a ₂ described above. When CA = a ₂ , the routine proceeds to step 210, and when CA ≠ a ₂ , this routine is terminated. In step 210, a reference value Eref corresponding to the intake air amount GN and the engine rotational speed NE (calculated separately) is obtained by referring to a three-dimensional map as shown in FIG. Next, at step 212, it is determined whether or not the integrated power supply amount Es is equal to or less than the determination reference value Eref. When Es> Eref, the operation is considered to be normal, and the process proceeds to step 216. When Es ≦ Eref, the abnormal operation is performed. Proceed to step 214 with regard to medium. In step 214, abnormality countermeasure processing such as restart of the electromagnetically driven valve is executed. In the final step 216, the integrated power supply amount Es is cleared in preparation for the next abnormality determination.
[0035]
Finally, a third embodiment will be described. In the first embodiment, the instantaneous power supplied to the moving destination of the valve body, that is, the coil on the side of sucking the valve body is observed, but the moving source of the valve body, that is, the coil on the side of releasing the adsorption of the valve body An abnormality can also be detected by looking at the instantaneous power supplied to. In the drive circuit shown in FIG. 2, it is possible to pass a current in the opposite direction to the coil. As shown in the command current Ic of Figure 10, at time t ₄ when releasing the adsorption of the plunger, in order to free vibration of the spring-mass system is made good response is effective to extinguish the residual magnetic field in the core Therefore, a reverse coil current flows from time t ₄ to time t ₆ .
[0036]
When a reverse coil current is supplied at the time of releasing the adsorption, a large difference occurs in the power supply current Is as shown in FIG. 10 between normal operation and step-out of the valve operation. Thus, at time t ₅ that is between from time t ₄ to time t _6, by measuring the instantaneous power of the power supply, as in the first embodiment, it is possible to detect an abnormality of the electromagnetic valve.
[0037]
As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to this, It will be easy for those skilled in the art to devise various embodiment.
[0038]
【The invention's effect】
As described above, according to the present invention, an abnormality in the operation of the electromagnetically driven valve is detected based on the power supplied from the power source that supplies electric power to the electromagnetically driven valve. Therefore, the abnormality detection accuracy is improved as compared with the prior art. .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an intake / exhaust electromagnetically driven valve according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a drive circuit for an electromagnetically driven valve according to an embodiment of the present invention.
FIG. 3 is a characteristic diagram (solid line) showing the relationship between the plunger position and the electromagnetic force (attraction force) exerted on the plunger by the upper electromagnet as a parameter, and the biasing force exerted by the plunger position and a pair of springs on the plunger. It is a characteristic view (broken line) showing the relationship with these.
FIG. 4 is a time chart of valve lift (A), upper coil command current (B), and lower coil command current (C).
FIG. 5 shows currents (coil command current Ic (solid line), coil actual current Im (dotted line) and power supply current Is (dashed line)) related to the movement source coil of the valve body, It is a time chart which shows the related electric current and valve lift about the time of (A) normal time and (B) step-out (abnormality).
FIG. 6 is a flowchart showing a processing procedure of an electromagnetically driven valve abnormality detection routine according to the first embodiment.
FIG. 7 is a diagram showing a map in which a determination reference value Pref for detecting an electromagnetically driven valve abnormality based on power supply power Ps is determined according to an intake air amount GN per one rotation of the engine.
FIG. 8 is a flowchart showing a processing procedure of an electromagnetically driven valve abnormality detection routine according to a second embodiment.
FIG. 9 is a diagram showing a map in which a determination reference value Eref for detecting an electromagnetically driven valve abnormality based on an integrated power supply power amount Es is determined according to an intake air amount GN per engine rotation and an engine speed NE.
FIG. 10 shows currents (coil command current Ic (solid line), coil actual current Im (dotted line) and power supply current Is (dashed line)) related to the movement source coil of the valve body, It is a time chart which shows the related electric current and valve lift at the time of (A) normal time and (B) step-out (abnormal), Comprising: It is a figure which concerns on 3rd Embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Valve body 12 ... Valve head 13 ... Valve face 14 ... Valve shaft 16 ... Plunger 20 ... Case 22 ... Upper core 23 ... Lower core 24 ... Upper coil 25 ... Lower coil 26 ... Upper spring 27 ... Lower spring 31 ... Valve guide 32 ... Internal combustion engine Intake / exhaust port 33 ... valve seats 40, 41, 42, 43 ... switching elements (transistors)
45 ... Coil current detection circuit 46 ... Current feedback circuit 47 ... Switching element drive circuit 48 ... Subtraction circuit 50 ... Power source 51 ... Power source current detection circuit 52 ... Power source voltage detection circuit 60 ... Engine electronic control unit

Claims (3)

The valve body is elastically supported at the neutral position by the biasing force of the elastic body, and the electromagnetic force generated by controlling the current flowing through the coil to a predetermined current value acts on the plunger integrated with the valve body. An abnormality detection method for an intake / exhaust electromagnetically driven valve configured to control the movement of the valve body by
An abnormality in the intake / exhaust electromagnetic drive valve, characterized in that an abnormality is determined when the power supply power obtained from the voltage and current of the power supply that supplies power to the electromagnetic drive valve at a predetermined time is below a predetermined reference value. Detection method. The valve body is elastically supported at the neutral position by the biasing force of the elastic body, and the electromagnetic force generated by controlling the current flowing through the coil to a predetermined current value acts on the plunger integrated with the valve body. An abnormality detection method for an intake / exhaust electromagnetically driven valve configured to control the movement of the valve body by
Integration of power supply power obtained from the voltage and current of the power supply that supplies power to the electromagnetically driven valve within a predetermined period including the period during which the valve element moves from the fully open position to the fully closed position or from the fully closed position to the fully open position. An abnormality detection method for an intake / exhaust electromagnetically driven valve, wherein an abnormality is determined when the amount is equal to or less than a predetermined reference value.   The abnormality detection method for an intake / exhaust electromagnetically driven valve according to claim 1 or 2, wherein the predetermined reference value is changed according to an operating state.

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