JP2007085318A - Control device of electromagnetic-drive valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an electromagnetic-drive valve improving control accuracy of electromagnets by suitably setting a cut-off frequency of an observer. <P>SOLUTION: The electronic control device 50 controls driving on the solenoid-drive valve which functions as an exhaust valve and drives a valve element 19 for opening and closing with electromagnetic force of the respective electromagnets 61, 62. A displacement state of the valve element 19 is detected by a displacement sensor 52. The electronic control device 50 estimates the displacement state of the valve element 19 by the observer after the elapse of predetermined time from a time when the displacement state of the valve element 19 detected by the displacement sensor 52 and controls the electromagnetic force of the respective electromagnets 61, 62 based on the estimated displacement state. The electronic control device 50 calculates a noise level to be overlapped with a detection signal of the displacement sensor 52 and sets the cut-off frequency of the observer so that the more the noise level calculated is high the more the cut-off frequency is low. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an electromagnetically driven valve that functions as an intake valve or an exhaust valve of an internal combustion engine.

  Various devices have been proposed for controlling the driving of an electromagnetically driven valve that opens and closes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine by electromagnetic force of an electromagnet. In such a control device, the electromagnetic force of the electromagnet is controlled so that the actual value of the displacement state (for example, lift position, etc.) of the valve body changes along a properly set lift curve. Here, since various external forces such as in-cylinder pressure, exhaust pressure, or intake pressure act on the valve body, the electromagnetic force is feedback controlled while reflecting the influence of these external forces in order to carry out such control accurately. Is done.

Here, when the control target is controlled through feedback of a state variable representing the internal state of the control target, it is necessary to detect all the state variables. However, in practice, there may be various inconveniences such as the presence of state variables that are difficult to detect and the need for many sensors to detect all state variables. Therefore, in order to suppress the occurrence of such inconveniences, it is desirable to set a state observer that estimates and reconstructs the remaining state variables from the detectable state variables, for example, a so-called observer. In such a control device, an internal state relating to the opening / closing behavior of the valve body is estimated using such an observer. More specifically, the external force and the displacement speed of the valve body are estimated.
JP 2002-266667 A

  By the way, a signal related to a detectable state variable is input to the observer. However, if noise is superimposed on this input signal, the observer's estimation accuracy decreases according to the magnitude of the noise. Therefore, when designing the observer, a cutoff frequency for reducing the influence of such noise is set. By setting the cut-off frequency, the level of the signal having the frequency higher than the set frequency is attenuated. Therefore, the noise having a relatively high frequency can be reduced.

  Here, the lower the cutoff frequency, the higher the noise reduction effect.On the other hand, the lower the cutoff frequency, the more the estimated value is calculated through the observer. Be late. That is, the responsiveness of the estimated value with respect to the actual value is lowered.

  In this way, when setting the cutoff frequency, the noise reduction effect and responsiveness are in a trade-off relationship. Therefore, unless the cutoff frequency is set appropriately, the control accuracy of the electromagnetically driven valve with respect to the electromagnet decreases. Therefore, for example, there is a risk that a malfunction such as an operating noise generated when the valve body is opened and closed becomes significant.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a control device for an electromagnetically driven valve that can improve the control accuracy of an electromagnet by appropriately setting the cutoff frequency of an observer. There is to do.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is an apparatus that controls the driving of an electromagnetically driven valve that opens and closes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine by an electromagnetic force of an electromagnet. A sensor that detects a displacement state; and an observer that estimates a displacement state of the valve body after a predetermined period of time has elapsed since the displacement state was detected, and controls the electromagnetic force based on the estimated displacement state. The gist of the control device for the electromagnetically driven valve is to include a variable means for changing the cutoff frequency of the observer.

  In this configuration, the displacement state of the valve body is detected by a sensor, and the displacement state of the valve body after a predetermined period of time has been detected by the observer after the displacement state is detected, and the estimated displacement state is obtained. Based on this, the electromagnetic force of the electromagnet is controlled. That is, the displacement state of the valve body after a predetermined period has been estimated based on the current displacement state of the valve body, and the electromagnetic force is controlled based on the estimated displacement state. For example, the estimated displacement state and the target displacement of the valve body By controlling the electromagnetic force based on the degree of deviation from the state, the actual value of the displacement state (for example, the lift position) of the valve body changes along a properly set lift curve.

  Here, regarding the noise reduction effect in the observer and the responsiveness of the estimated value with respect to the actual value, the priorities change under various conditions. Therefore, in this configuration, the cutoff frequency of the observer is made variable so that the noise reduction effect can be prioritized and the responsiveness of the estimated value can be prioritized. Therefore, according to this configuration, it becomes possible to appropriately set the observer cutoff frequency in accordance with the change in the priority regarding the noise reduction effect and the responsiveness of the estimated value, thereby improving the control accuracy of the electromagnet. To be able to.

  According to a second aspect of the present invention, in the electromagnetically driven valve control device according to the first aspect, the variable means includes a noise calculating means for calculating a noise level to be superimposed on a detection signal of the sensor. The gist is to set the cut-off frequency so that the cut-off frequency becomes lower as the noise level increases.

  According to this configuration, the noise reduction effect can be enhanced as the noise level increases. In addition, the cutoff frequency is set such that the cutoff frequency decreases as the noise level increases, and conversely, the cutoff frequency is set such that the cutoff frequency increases as the noise level decreases. Therefore, when the noise level is small and the noise reduction effect is not so necessary, the responsiveness of the estimated value can be improved. When calculating the noise level, the difference between the maximum value and the minimum value of the output signal of the sensor when the displacement state of the valve body is constant is obtained, and this is used as the noise level. The standard deviation of the output signal of the sensor when the displacement state of the valve body is constant can be obtained and used as a noise level.

  Further, in the case of calculating the noise level in this way, as in the invention according to claim 3, when the noise level exceeds a preset threshold value, determination means for determining that the sensor is abnormal. It is also possible to adopt a configuration including:

  According to a fourth aspect of the present invention, in the electromagnetically driven valve control device according to the first aspect, the variable means variably sets the cut-off frequency in accordance with an operating region of the valve body. To do.

  When the electromagnetic force of the electromagnet is controlled, the valve body is held at a displacement end (for example, a valve opening position or a valve closing position) or is displaced from one displacement end toward the other displacement end. However, there are areas where it is better to prioritize the noise reduction effect depending on the operating area of the valve body, and areas where it is better to prioritize the responsiveness of the estimated value. Therefore, in the same configuration, the cut-off frequency is variably set according to the operating region of the valve body, whereby the cut-off frequency according to the operating region of the valve body can be set appropriately. It becomes like this.

In variably setting the cut-off frequency according to the operation region of the valve body, the inventions according to claims 5 and 6 can be applied.
According to a fifth aspect of the present invention, in the control device for an electromagnetically driven valve according to the fourth aspect, the operating region in which the valve body is held at the displacement end, and the valve body is displaced from one displacement end to the other. The gist of the invention is that the cut-off frequency set in at least one of the operating regions in which power supply to the electromagnet is stopped in the process of displacement to the end is set to be lower than in other operating regions. To do.

  In the operating region where the valve body is held at its displacement end, the displacement state of the valve body remains constant without change. In such a region, the noise reduction effect is prioritized over the responsiveness of the estimated value. Is good. Also, in the operation region where the power supply to the electromagnet is stopped in the process in which the valve body is displaced from one displacement end to the other displacement end, the control of the electromagnet is temporarily interrupted. It is better to prioritize the noise reduction effect over the responsiveness of the estimated value. Therefore, in this configuration, the cut-off frequency in the operation region where it is better to give priority to such a noise reduction effect is set lower than that in other operation regions. Therefore, according to the configuration, when the operation region of the valve body is in a region where it is better to give priority to the noise reduction effect, the noise reduction effect can be surely obtained.

  The invention according to claim 6 is the electromagnetically driven valve control device according to claim 4 or 5, wherein the cutoff frequency set in the operating region immediately before the valve body reaches its displacement end is: The gist of the present invention is that it is set so as to be higher than other operating regions.

  In the operating region immediately before the valve body reaches its displacement end, the electromagnetic force of the electromagnet is controlled more precisely than in other operating regions, thereby reducing the operating noise generated when the valve body is opened and closed. . Here, when the responsiveness of the estimated value through the observer is low, the delay in calculating the estimated value with respect to the change in the displacement state of the valve element becomes large. Before the calculation is made, the valve body reaches the displacement end, and there is a possibility that the control of the electromagnet performed for reducing the operation noise may not be in time. Therefore, in the operation region immediately before the valve body reaches the displacement end, it is better to give priority to the improvement of the responsiveness of the estimated value than the noise reduction effect. Therefore, in this configuration, the cutoff frequency in the operating region where it is better to give priority to the responsiveness of such an estimated value is set higher than in other operating regions. Therefore, according to the configuration, when the operating region of the valve body is in a region where it is better to give priority to the responsiveness of the estimated value through the observer, the responsiveness of the estimated value can be reliably improved. It becomes like this.

  A seventh aspect of the present invention is the electromagnetically driven valve control device according to the first aspect, wherein the variable means sets the cutoff frequency so that the cutoff frequency becomes higher as the engine speed is lower. The gist is to do.

  The lower the engine speed, the lower the background noise and the easier it is to hear the operating sound of the valve body. To reduce the operating sound of such a valve body, improve the responsiveness of the estimated value through the observer as described above. It is better to do so. Therefore, in this configuration, the cutoff frequency becomes higher as the engine speed is lower, that is, priority is given to the responsiveness of the estimated value over the noise reduction effect. Therefore, according to the same configuration, when the engine speed is better to give priority to the responsiveness of the estimated value through the observer, the responsiveness of the estimated value can be reliably improved, and consequently The operating noise of the valve body can be suitably reduced.

  On the other hand, a determination process may be performed to determine whether or not the valve body is reliably displaced to its displacement end, that is, whether or not the valve body is operating normally. In this case, by performing the determination based on the estimated displacement state (the displacement state of the valve body after a predetermined period estimated based on the current displacement state of the valve body), abnormal operation of the valve body Can be detected early. Here, if the valve element malfunctions in the high rotational speed range, the engine operating state and emission are greatly affected. Therefore, it is desirable to particularly improve the abnormality determination accuracy in such rotational speed range. In this regard, according to the same configuration, the cutoff frequency is set to be higher as the engine speed is lower, and conversely, the cutoff frequency is set to be lower as the engine speed is higher. The noise reduction effect is prioritized as the rotation speed region is reached, whereby the estimation accuracy of the observer, that is, the estimation accuracy of the estimated displacement state with respect to the actual value of the displacement state is increased. Therefore, according to the same configuration, it is possible to reliably improve the noise reduction effect at the engine rotation speed where it is better to give priority to the noise reduction effect. As a result, when performing abnormality determination as described above, The determination accuracy can be increased.

  According to an eighth aspect of the present invention, in the electromagnetically driven valve control device according to the first aspect, the variable means sets the cutoff frequency so that the cutoff frequency becomes lower as the engine load is higher. This is the gist.

  Various external forces such as in-cylinder pressure, exhaust pressure, or intake pressure act on the valve body, and the influence of the external force on the operation of the valve body increases as the engine load increases. Therefore, the control of the displacement state of the valve body, in other words, the control of the electromagnet becomes difficult due to such disturbance factors as the engine load increases. Therefore, the higher the engine load, the higher the estimation accuracy of the estimated displacement state by the observer by giving priority to the noise reduction effect over the responsiveness of the estimated value, so that the displacement state of the valve body can be grasped more accurately. Is desirable. In this regard, in this configuration, the cutoff frequency is lowered as the engine load is higher, in other words, the noise reduction effect is given priority as the engine load is higher. Therefore, according to this configuration, in an engine load state where it is better to prioritize the noise reduction effect, the noise reduction effect can be reliably improved, and the displacement state of the valve body can be accurately estimated. become able to. Therefore, the controllability of the electromagnet can be improved even in a state where the influence of the disturbance factor is large on the operation of the valve body.

  The invention according to claim 9 is an apparatus for controlling the driving of an electromagnetically driven valve that opens and closes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine by the electromagnetic force of an electromagnet. A sensor that detects a displacement state; and an observer that estimates a displacement state of the valve body after a predetermined period of time has elapsed since the displacement state was detected, and controls the electromagnetic force based on the estimated displacement state. In the electromagnetically driven valve control device, when the valve body is an exhaust valve, the cutoff frequency of the observer is lower than when the valve body is an intake valve. The gist is to set.

  A relatively large external force such as in-cylinder pressure acts on the exhaust valve. Therefore, control of the displacement state of the exhaust valve, in other words, control of the electromagnet on the exhaust valve side becomes difficult due to such disturbance factors as compared with the intake valve side. In this regard, as described above, in a state where such control is difficult due to the disturbance factor, the noise reduction effect is prioritized over the responsiveness of the estimated value to improve the estimation accuracy of the estimated displacement state by the observer, and the displacement of the valve body It is desirable to grasp the state more accurately. Therefore, in this configuration, when the valve body is an exhaust valve, the cut-off frequency is made lower than when the valve body is an intake valve. That is, the noise reduction effect is prioritized in the control on the exhaust valve side as compared with the control on the intake valve side. Therefore, according to the same configuration, it is possible to reliably improve the noise reduction effect for the valve body that should prioritize the noise reduction effect, and accurately estimate the displacement state of the valve body. become able to. Therefore, the controllability of the electromagnet on the exhaust valve side that is easily affected by disturbance factors can be improved.

  According to a tenth aspect of the present invention, in the electromagnetically driven valve control device according to the fourth to ninth aspects of the present invention, a noise calculating means for calculating a noise level to be superimposed on the detection signal of the sensor is provided and is calculated. If the noise level exceeds a preset threshold, the gist is to include determination means for determining that the sensor is abnormal.

  According to this configuration, in the electromagnetically driven valve control device according to any one of claims 4 to 9, an abnormality of the sensor can be detected. Even in the same configuration, when calculating the noise level, the difference between the maximum value and the minimum value of the output signal of the sensor when the displacement state of the valve body is constant is obtained, and this is referred to as the noise level. It is possible to obtain the standard deviation of the output signal of the sensor when the displacement state of the valve body is constant, and to make this a noise level.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a control device that opens and closes an intake valve and an exhaust valve of an internal combustion engine will be described.

  In the present embodiment, both the intake valve and the exhaust valve are configured as electromagnetically driven valves that are driven to open and close based on the electromagnetic force of the electromagnet. Since these intake valves and exhaust valves have the same configuration and drive control mode, the exhaust valves will be described below as an example.

  As shown in FIG. 1, the exhaust valve 10 includes a valve shaft 20 that is supported by a cylinder head 18 so as to be reciprocally movable, and an armature shaft that is disposed coaxially with the valve shaft 20 and reciprocates together with the valve shaft 20. 26, and a valve body 19 constituted by an umbrella portion 16 provided at one end of the valve shaft 20, and an electromagnetic drive portion 21 for reciprocatingly driving the valve body 19.

  An exhaust port 14 that communicates with the combustion chamber 12 is formed in the cylinder head 18, and a valve seat 15 is formed around the opening periphery of the exhaust port 14. As the valve shaft 20 reciprocates, the umbrella portion 16 is separated from and seated on the valve seat 15 so that the exhaust port 14 is opened and closed.

  In the valve shaft 20, a lower retainer 22 is fixed to the end opposite to the end where the umbrella portion 16 is provided. A lower spring 24 is disposed in a compressed state between the lower retainer 22 and the cylinder head 18. The valve element 19 is biased in the valve closing direction (upward in FIG. 1) by the elastic force of the lower spring 24.

  A disk-shaped armature 28 made of a high magnetic permeability material is fixed to a substantially central portion in the axial direction of the armature shaft 26, and an applicator 30 is fixed to one end of the armature shaft 26. The end of the armature shaft 26 opposite to the end to which the applicator 30 is fixed contacts the end of the valve shaft 20 on the lower retainer 22 side.

  In the casing (not shown) of the electromagnetic drive unit 21, an upper core 32 is positioned and fixed between the upper retainer 30 and the armature 28. Similarly, in the casing, a lower core 34 is fixed between the armature 28 and the lower retainer 22. Each of the upper core 32 and the lower core 34 is formed in an annular shape from a high magnetic permeability material, and an armature shaft 26 is inserted in a central portion thereof so as to be able to reciprocate.

  An upper spring 38 is disposed in a compressed state between the upper cap 36 and the upper retainer 30 provided in the casing. The valve element 19 is biased in the valve opening direction (downward in FIG. 1) by the elastic force of the upper spring 38.

  A displacement amount sensor 52 for detecting the displacement state of the exhaust valve 10 is attached to the upper cap 36. The displacement sensor 52 outputs a voltage signal that changes in accordance with the distance between the sensor 52 and the applicator 30. Therefore, the displacement amount of the armature shaft 26 and the valve shaft 20, that is, the displacement amount X (that is, the lift position) of the valve body 19 can be detected based on the voltage signal.

  An annular groove 40 centering on the axis of the armature shaft 26 is formed on a surface of the upper core 32 facing the armature 28, and an annular upper coil 42 is disposed in the groove 40. The upper coil 42 and the upper core 32 constitute an electromagnet (closed drive electromagnet) 61 for driving the valve body 19 in the valve closing direction.

  On the other hand, an annular groove 44 centering on the axis of the armature shaft 26 is formed on the surface of the lower core 34 facing the armature 28, and an annular lower coil 46 is disposed in the groove 44. The lower coil 46 and the lower core 34 constitute an electromagnet (opening drive electromagnet) 62 for driving the valve element 19 in the valve opening direction.

  The coils 42 and 46 of the electromagnets 61 and 62 are energized and controlled by an electronic control unit 50 that performs various controls of the internal combustion engine. This electronic control unit 50 includes a CPU (Central Processing Unit), a memory, a drive circuit for supplying exciting current to the coils 42 and 46 of the electromagnets 61 and 62, an input circuit for receiving detection signals from various sensors, An A / D converter (all not shown) for A / D converting the detection signal is provided. The detection signals taken into the input circuit include the detection signal of the displacement sensor 52, the engine speed NE, the throttle valve opening (throttle opening TA), and the accelerator pedal operation amount (accelerator operation amount ACCP). Etc.

  FIG. 1 shows the state of the valve body 19 when no drive current is supplied to each of the electromagnets 61 and 62 and no electromagnetic force is generated in these electromagnets 61 and 62. In this state, the armature 28 is not attracted by the electromagnetic force of the electromagnets 61 and 62, and stops at an intermediate position between the cores 32 and 34 where the urging forces of the springs 24 and 38 are balanced. Further, in this state, the umbrella portion 16 is separated from the valve seat 15 and the exhaust valve 10 is in a half-open state. Hereinafter, the position of the valve body 19 in this state is referred to as a neutral position.

  Next, a mode when the exhaust valve 10 is displaced from one displacement end toward the other displacement end, that is, an operation mode of the exhaust valve 10 that is driven to open and close through energization control for the electromagnets 61 and 62 will be described.

  In the closed state of the exhaust valve 10, a holding current for holding the exhaust valve 10 in the fully closed state is supplied to the closing drive electromagnet 61. When this holding current is supplied, the armature 28 is attracted by the electromagnetic force of the closing drive electromagnet 61, abuts against the upper core 32 against the elastic force of the upper spring 38, and the umbrella portion 16 contacts the valve seat 15. The seated state is maintained.

  Next, when the opening drive timing of the exhaust valve 10 comes, the energization control for the closing drive electromagnet 61 is performed for a period from that time until the valve body 19 reaches a position on the valve closing side by a predetermined amount from the neutral position. . During this period, the armature 28 is separated from the upper core 32 so that the valve element 19 is displaced in the valve opening direction, and the displacement driving magnet is not excessively increased by an external force based on the in-cylinder pressure or the exhaust pressure. The electromagnetic force that attracts the valve body 19 (armature 28) in the valve closing direction is controlled through adjustment of the drive current to 61.

  Then, when the valve body 19 is displaced by a predetermined amount from the fully closed position, the closing drive electromagnet 61 and the opening drive electromagnet 61 are used for a period from that time until the valve body 19 reaches the valve opening side position by a predetermined amount from the neutral position. Any supply of drive current to the electromagnet 62 is stopped.

  Thereafter, when the valve body 19 is further displaced by the elastic force of the upper spring 38 and reaches a position on the valve opening side by a predetermined amount from the neutral position, the valve body 19 is opened for a period from that time until the valve body 19 reaches the fully open position. Energization control for the driving electromagnet 62 is performed. During this period, the electromagnetic force that attracts the valve body 19 in the valve opening direction is controlled through adjustment of the drive current to the electromagnet 62 for opening drive so that the valve body 19 reliably reaches the fully open position with a predetermined displacement speed. In order to reduce an operation sound generated when the valve body 19 reaches the fully open position (for example, a sound generated when the armature 28 contacts the lower core 34), immediately before the valve body 19 reaches the fully open position, The opening drive electromagnet 62 is precisely controlled so that the displacement speed of the valve body 19 gradually decreases. (Hereinafter, this control for reducing operating noise is referred to as operating noise reduction control).

  When the valve body 19 reaches the fully open position, a holding current for holding the exhaust valve 10 in the fully open state is supplied to the open driving electromagnet 62 until a predetermined period elapses from that time. By supplying this holding current, the armature 28 is attracted by the electromagnetic force of the open driving electromagnet 62 and abuts against the lower core 34 against the elastic force of the lower spring 24, and the umbrella portion 16 is removed from the valve seat 15. It is held in the most separated state.

  Next, when a predetermined period elapses after the valve element 19 reaches the fully open position and the closing drive timing of the exhaust valve 10 comes, the valve element 19 is moved to a position on the valve opening side by a predetermined amount from the neutral position. The energization control for the open drive electromagnet 62 is performed until the time is reached. During this period, the armature 28 is separated from the lower core 34 and the valve body 19 is displaced in the valve closing direction, and the opening driving electromagnet is prevented so that the displacement speed at that time is not excessive due to the external force based on the in-cylinder pressure or the exhaust pressure. The electromagnetic force that attracts the valve body 19 in the valve opening direction is controlled through the adjustment of the drive current to 62.

  Then, when the valve body 19 is displaced by a predetermined amount from the fully open position, the closed drive electromagnet 61 and the open drive electromagnet from that time until the valve body 19 reaches a position on the valve closing side by a predetermined amount from the neutral position. Any supply of drive current to 62 is stopped.

  Thereafter, when the valve body 19 is further displaced by the elastic force of the lower spring 24 and reaches the position on the valve closing side by a predetermined amount from the neutral position, the period from that time until the valve body 19 reaches the fully closed position, Energization control for the closing drive electromagnet 61 is performed. During this period, the electromagnetic force that attracts the valve body 19 in the valve closing direction is controlled through adjustment of the drive current to the closing drive electromagnet 61 so that the valve body 19 reliably reaches the fully closed position with a predetermined displacement speed. . It should be noted that an operation sound generated when the valve body 19 reaches the fully closed position (for example, a sound generated when the armature 28 contacts the upper core 32 or a seating sound generated when the umbrella portion 16 contacts the valve seat 15). For example, the operation noise reduction control is performed immediately before the valve body 19 reaches the fully closed position.

  When the valve body 19 reaches the fully closed position, a holding current for holding the exhaust valve 10 in the fully closed state is supplied to the closing drive electromagnet 61 from that time until the next opening drive timing comes. Will be supplied again.

The outline of the displacement amount control of the valve body 19 in this embodiment is as follows.
That is, the electromagnetic force of each of the electromagnets 61 and 62 is controlled so that the actual value of the displacement amount of the valve body 19 changes along a lift curve appropriately set for engine operation. Here, various external forces such as in-cylinder pressure and exhaust pressure act on the valve body 19, and when the valve body 19 is an intake valve, various external forces such as intake pressure act. Therefore, the electromagnetic force is feedback-controlled while reflecting the influence of these external forces in order to accurately control the displacement amount of the valve body 19 along the lift curve.

  Here, when the control target is controlled through feedback of a state variable representing the internal state of the control target, it is necessary to detect all the state variables. However, in practice, there may be various inconveniences such as the presence of state variables that are difficult to detect and the need for many sensors to detect all state variables. Therefore, in order to suppress the occurrence of such inconvenience, a state observer that estimates and reconstructs the remaining state variables from the detectable state variables, that is, a so-called observer is set. This observer is set as an observer for observing the internal state based on a spring / mass vibration system model that simulates the opening / closing behavior of the valve body 19.

  Then, as shown in FIG. 2, when the displacement amount Xi is detected by the displacement amount sensor 52 at time t (i), the valve body 19 at time t (i) is based on the displacement amount Xi and the equation of motion. A displacement speed Vi is calculated. Based on the displacement amount Xi, the displacement speed Vi, and the like, the displacement amount X (i + 1) of the valve body 19 after a predetermined period Δt has elapsed since the displacement amount Xi was detected is estimated by the observer. Then, based on the degree of deviation ΔX between the target displacement amount Xt (i + 1) at time t (i + 1) and the displacement amount X (i + 1) estimated through the observer, the control currents of the closed drive electromagnet 61 and the open drive electromagnet 62 are changed. Feedback controlled. Thus, in this embodiment, the displacement state of the valve body after a predetermined period has been predicted based on the current displacement state of the valve body 19, and the electromagnetic force is controlled in advance based on the predicted displacement state. As a result, the actual value of the displacement amount of the valve body 19 appropriately changes along the lift curve. Hereinafter, the displacement amount X (i + 1) estimated by the observer is referred to as an estimated displacement amount Xs.

  By the way, a signal related to a detectable state variable is input to the observer. However, if noise is superimposed on this input signal, the observer's estimation accuracy decreases according to the magnitude of the noise. Therefore, when designing the observer, a cutoff frequency for reducing the influence of such noise is set. By setting the cut-off frequency, the level of the signal having the set frequency or higher is attenuated, and the noise having a relatively high frequency can be reduced.

  Here, as shown in FIG. 3, the noise reduction effect becomes higher as the cut-off frequency is set to a lower value. On the other hand, as the cut-off frequency is set to a lower value, the estimated displacement amount Xs through the observer becomes smaller. The calculation is delayed with respect to the change of the actual value. That is, the responsiveness of the estimated displacement amount Xs with respect to the actual value is lowered.

  As described above, when setting the cutoff frequency, the noise reduction effect and the responsiveness have a trade-off relationship. Therefore, unless the cutoff frequency is set appropriately, the control accuracy for the electromagnets 61 and 62 is lowered. Therefore, for example, there is a possibility that a malfunction such as the above-described operation sound generated when the valve body 19 is opened or closed becomes significant.

  Therefore, in this embodiment, the control frequency of the electromagnets 61 and 62 is improved by variably setting the observer cutoff frequency in the following manner and setting it appropriately.

FIG. 4 shows a processing procedure for setting the cutoff frequency. This process is repeatedly executed by the electronic control device 50 at predetermined intervals.
When this process is started, it is first determined whether or not the valve body 19 is in the holding mode or the neutral position stop mode (S100). This holding mode means a state in which the exhaust valve 10 is in a fully open position or a fully closed position, and the neutral position stop mode is in a neutral position before the exhaust valve 10 is driven. Or a neutral position after the drive is stopped. That is, here, it is determined whether or not the displacement amount of the valve body 19 remains constant. Whether or not the valve body 19 is in each of the above modes can be determined based on the control current of the electromagnets 61 and 62, the detection signal of the displacement sensor 52, or the like.

Then, when the valve body 19 is not in the holding mode or the neutral position stop mode (S100: NO), this process is temporarily ended.
On the other hand, when the valve body 19 is in the holding mode or the neutral position stop mode (S100: YES), the noise level applied to the detection signal of the displacement sensor 52, that is, the voltage noise VN is measured (S110). ). Here, the difference between the maximum value and the minimum value is obtained for the output voltage of the displacement sensor 52 when the displacement state of the valve body 19 is constant, and this is measured as the voltage noise VN. Note that the standard deviation of the output voltage of the displacement sensor 52 when the displacement state of the valve body 19 is constant may be obtained and used as the noise level.

  Next, the cutoff frequency Fc is variably set based on the voltage noise VN (S120). Here, as shown in FIG. 5, the cutoff frequency Fc is variably set so that the higher the voltage noise VN is, that is, the higher the noise level is, the lower the cutoff frequency Fc is. The

  FIG. 6 shows the effect of the cutoff frequency setting process. As shown in FIG. 6, when the cut-off frequency is a constant value, the amount of noise N reflected in the estimated displacement amount Xs increases as the voltage noise VN increases. On the other hand, in the present embodiment in which the cut-off frequency setting process is executed, the cut-off frequency Fc is set low as the voltage noise VN increases. Therefore, the noise reduction effect is enhanced with the increase of the same voltage noise VN, so that the noise amount N is less than or equal to the maximum noise amount Nmax allowed for ensuring the control accuracy of the electromagnets 61 and 62. Can be suppressed. Since the noise amount N can be set to a certain value or less in this way, the estimation accuracy of the estimated displacement amount Xs is improved, and thereby the current control accuracy of the electromagnets 61 and 62 is also improved. Therefore, the operation noise can be sufficiently reduced through the operation noise reduction control.

  Further, the voltage noise VN is measured based on the output signal of the displacement sensor 52, and the cut-off frequency Fc is variably set based on this measurement value. Even when the output characteristics of the displacement sensor 52 vary, the cutoff frequency Fc can be set appropriately. Therefore, the estimation accuracy of the estimated displacement amount Xs is improved, and the current control accuracy of the electromagnets 61 and 62 is also improved.

  The cutoff frequency Fc is set to be lower as the voltage noise VN is larger. Conversely, the cutoff frequency Fc is higher as the voltage noise VN is smaller, that is, as the noise level is smaller. The cutoff frequency Fc is variably set. Therefore, when the noise level is small and the noise reduction effect is not so necessary, the responsiveness of the estimated displacement amount Xs is increased, and this also improves the current control accuracy of the electromagnets 61 and 62.

According to this embodiment described above, the following effects can be obtained.
(1) The displacement state of the valve body 19 is detected by the displacement amount sensor 52, and the displacement state of the valve body 19 after a predetermined period has elapsed after the displacement state is detected is estimated by an observer. The electromagnetic force of each electromagnet 61, 62 is controlled based on the displacement state. In other words, the displacement state of the valve body after a predetermined period has been estimated based on the current displacement state of the valve body 19, and the electromagnetic force is controlled based on the estimated displacement state. The actual value of the displacement state can be changed along a properly set lift curve.

  Here, regarding the noise reduction effect in the observer and the responsiveness of the estimated value (estimated displacement amount Xs) with respect to the actual value, those priorities change under various conditions. Therefore, in this embodiment, the cutoff frequency Fc of the observer is made variable so that the noise reduction effect can be prioritized and the estimated value response can be prioritized. Therefore, the observer's cutoff frequency Fc can be appropriately set in accordance with the change in the priority regarding the noise reduction effect and the responsiveness of the estimated value, thereby improving the control accuracy of the electromagnets 61 and 62. Will be able to.

  (2) When variably setting the cut-off frequency Fc, a noise level to be superimposed on the detection signal of the displacement sensor 52 is calculated, and the cut-off frequency Fc becomes lower as the calculated noise level increases. The off frequency Fc is set.

Therefore, the noise reduction effect can be enhanced as the noise level increases. In addition, since the cutoff frequency Fc is set to be higher as the noise level is smaller, the response of the estimated displacement amount Xs can be improved when the noise level is small and the noise reduction effect is not so necessary. become able to.
(Second Embodiment)
Next, a second embodiment of the present invention will be described focusing on the differences from the first embodiment.

  The valve body 19 is held at its displacement end (for example, a fully open position or a fully closed position) by controlling the electromagnetic force of the electromagnets 61 and 62, or from one displacement end to the other displacement end. There are areas where it is better to prioritize the noise reduction effect according to the operating area of the valve body 19 and areas where it is better to prioritize the responsiveness of the estimated displacement amount Xs. Therefore, in the present embodiment, the cutoff frequency Fc is variably set according to the operating region of the valve body 19.

Hereinafter, the variable setting of the cutoff frequency in the present embodiment will be described with reference to FIGS.
FIG. 7 shows the procedure of the cutoff frequency setting process in this embodiment. This process is repeatedly executed by the electronic control device 50 at predetermined intervals.

When this process is started, first, the operation mode of the valve body 19 is read (S200). This operation mode corresponds to the operation region of the valve body 19, and details thereof will be described later.
Next, the cut-off frequency Fc corresponding to the operation mode is selected (S210), and this process is temporarily terminated.

  FIG. 8 shows a correspondence relationship between the cut-off frequency Fc set in step S210 and each operation mode. This correspondence relationship is stored in advance in the memory of the electronic control unit 50. Further, the set frequency increases in the order of low frequency FcL <medium frequency FcM <high frequency FcH. Each operation mode shown in FIG. 8 and the cut-off frequency Fc set in each operation mode are as follows.

A: Holding mode This holding mode means a state in which the valve element 19 is in the fully closed position (time t3 to t4 shown in FIG. 9) or fully opened position (time t8 to t9 shown in FIG. 9). The valve element 19 is an operation region that is held at the displacement end.

  In this mode, the valve body 19 is held at the displacement end, and the displacement amount X and the control current of the closing drive electromagnet 61 are constant without change. Therefore, in this mode, it is preferable to prioritize the noise reduction effect over the responsiveness of the estimated displacement amount Xs to improve the estimation accuracy of the estimated displacement amount Xs. That is, in a state where the actual displacement amount X does not change, various coefficients in the observer are calibrated based on the difference between the displacement amount X and the estimated displacement amount Xs, or the detection signal of the displacement amount sensor 52 is calibrated. This is because when such calibration is performed, the accuracy of the calibration is improved by improving the estimation accuracy of the estimated displacement amount Xs. Therefore, the cut-off frequency Fc in this mode is set to a low frequency FcL, which is a lower frequency, in order to prioritize the noise reduction effect.

B: Hold-off mode This hold-off mode is the next mode to the above-mentioned hold mode, and after the opening drive timing of the exhaust valve 10 arrives, the valve element 19 is on the valve-closing side by a predetermined amount from the neutral position. It means a state in which the energization control is performed on the closing drive electromagnet 61 as described above during a period until reaching the position (time t4 to t5 shown in FIG. 9). (Similarly, the opening driving electromagnet 62 as described above is a period from when the closing driving timing of the exhaust valve 10 arrives until the valve body 19 reaches a position on the valve opening side by a predetermined amount from the neutral position. (The state in which the energization control is performed on is also referred to as the hold-off mode)
In this mode, in order to achieve both the response of the estimated displacement amount Xs and the noise reduction effect, the cutoff frequency Fc is in the vicinity of the middle between the low frequency FcL set at a low frequency and the high frequency FcH set at a high frequency. The medium frequency FcM set to the value is set.

C: Non-energized mode This non-energized mode is the next mode to the hold-off mode, in which the valve body 19 is displaced from the fully closed position by the predetermined amount, and then the valve body 19 is further opened by a predetermined amount. This is a state in which power supply to the closed drive electromagnet 61 and the open drive electromagnet 62 is stopped during a period until reaching the valve position (time t5 to t6 shown in FIG. 9). (Similarly, during the period from when the valve body 19 is displaced by the predetermined amount from the fully open position until the valve body 19 reaches the valve-closed position by the predetermined amount, the closed drive electromagnet 61 and the open drive are provided. (The state in which power supply to the electromagnet 62 is stopped is also referred to as this non-energized mode.)
In this mode, the control of the electromagnets 61 and 62 is temporarily interrupted. Therefore, the noise reduction effect is prioritized over the responsiveness of the estimated displacement amount Xs, and the noise is superimposed on the detection signal of the displacement amount sensor 52. It is better to suppress a decrease in estimation accuracy of the estimated displacement amount Xs. Therefore, the cut-off frequency Fc in this mode is set to a low frequency FcL that is a lower frequency.

D: Suction Mode This suction mode is the next mode to the non-energized mode, and is a period from when the valve body 19 reaches the valve-opening position by the predetermined amount until just before reaching the fully-open position (FIG. 9). The time t6 to t7) shown in FIG. 4 indicates a state in which energization control is performed on the electromagnet 62 for opening drive. (Similarly, the state in which the energization control for the closing drive electromagnet 61 is performed during a period from when the valve body 19 reaches the valve closing position by the predetermined amount until just before reaching the fully closed position, This is called suction mode.)
In this mode, the cutoff frequency Fc is set to the medium frequency FcM in order to achieve both the response of the estimated displacement amount Xs and the noise reduction effect.

E: Seating mode This seating mode is the next mode to the suction mode described above, and it is opened during the period from the time when the valve body 19 reaches the fully open position until it reaches the fully open position (time t7 to t8 shown in FIG. 9). It means a state in which energization control for the driving electromagnet 62 is performed. (Similarly, during the period from the time when the valve body 19 reaches the fully closed position to the time when the valve body 19 reaches the fully closed position (time t2 to t3 shown in FIG. 9, etc.), the energization control for the closing drive electromagnet 61 is performed. (This is also called this sitting mode.)
In this mode, the operation noise reduction control is performed as described above, and the electromagnetic force of the electromagnet is more precisely controlled than in other modes. Here, when the responsiveness of the estimated displacement amount Xs at the observer is low, the calculation delay of the estimated displacement amount Xs becomes large with respect to the change in the displacement amount of the valve body 19, and the valve body 19 reaches its displacement end. In a very short time such as immediately before, the valve body 19 reaches the displacement end before the estimated displacement amount Xs is calculated, and there is a possibility that the control of the electromagnet may not be in time. Therefore, in the operation region immediately before the valve body 19 reaches the displacement end, it is better to give priority to the improvement in the response of the estimated displacement amount Xs than the noise reduction effect. Therefore, in this mode, the cutoff frequency Fc in this mode is set to a high frequency FcH, which is a higher frequency, in order to give priority to the responsiveness of the estimated displacement amount Xs.

F: Initial mode In this initial mode, when the operation of the valve body 19 is started, such as when the engine is started, the displacement state of the valve body 19 changes from the neutral position to the vicinity of the displacement end (for example, the fully closed position). This means a state in which energization control is performed on each of the electromagnets 61 and 62 during the period (time t1 to t2 shown in FIG. 9). In this mode, the electromagnets 61 and 62 are energized alternately to generate self-excited vibration in the valve body 19. By utilizing such self-excited vibration, the valve element 19 can be attracted from the neutral position to the vicinity of the displacement end with a smaller electromagnetic force. In other words, it is possible to use a smaller electromagnet as compared with the case where the valve body 19 is sucked at a stroke from the neutral position to the vicinity of the displacement end. In this mode, the cut-off frequency Fc is set to the medium frequency FcM in order to achieve both the response of the estimated displacement amount Xs and the noise reduction effect.

G: Stop mode This stop mode is a period during which the displacement state of the valve body 19 converges toward the neutral position when the operation of the valve body 19 is stopped, such as when the engine is stopped (shown in FIG. 9). It means a state in which power supply to the closed drive electromagnet 61 and the open drive electromagnet 62 is stopped at times t9 to t10). In this mode, the cut-off frequency Fc is set to the medium frequency FcM in order to achieve both the response of the estimated displacement amount Xs and the noise reduction effect.

Incidentally, whether or not the valve body 19 is in each of the above modes can be determined based on the control current of the electromagnets 61 and 62, the detection signal of the displacement sensor 52, or the like.
In this embodiment, the cut-off frequency Fc in the holding mode and the non-energized mode is set to the low frequency FcL, but only the cut-off frequency in either mode is set to the low frequency FcL. Also good.

According to the present embodiment described above, the following operational effects can be obtained in addition to the operational effect of (1) described in the first embodiment.
(3) The valve body 19 is held at its displacement end or is displaced from one displacement end toward the other displacement end. There are areas that should be prioritized and areas that should be prioritized to the responsiveness of estimated values. Therefore, in the present embodiment, the cut-off frequency Fc is variably set according to the operation region (operation mode) of the valve body 19, whereby the cut-off frequency according to the operation region of the valve body 19 is set. It becomes possible to set appropriately.

  (4) In at least one of the operation region in which the valve body 19 is held at the displacement end and the operation region in which power supply to the electromagnet is stopped in the process in which the valve body 19 is displaced from one displacement end to the other displacement end The set cut-off frequency Fc is set to be lower than that in other operation regions. That is, it is better to give priority to the noise reduction effect, and the cut-off frequency in such an operation region is set lower than that in other operation regions. Therefore, when the operation region of the valve body 19 is in a region where it is better to give priority to the noise reduction effect, the noise reduction effect can be reliably obtained.

(5) Further, the cutoff frequency Fc set in the operating region immediately before the valve body 19 reaches the displacement end is set to be higher than that in the other operating regions. That is, the cut-off frequency Fc in the operation region where it is better to give priority to the responsiveness of the estimated value (estimated displacement amount Xs) of the observer is set higher than that in the other operation regions. Therefore, when the operating region of the valve body 19 is in a region where it is better to give priority to the responsiveness of the estimated value through the observer, the responsiveness of the estimated value can be reliably improved.
(Third embodiment)
Next, a third embodiment of the present invention will be described focusing on the differences from the first embodiment.

  In the first embodiment, the cutoff frequency Fc is variably set based on the noise level, but in this embodiment, the cutoff frequency Fc is variably set based on the engine speed.

  FIG. 10 shows the procedure of the cutoff frequency setting process in the present embodiment. FIG. 11 shows how the cut-off frequency Fc is set in the cut-off frequency setting process. This process is repeatedly executed by the electronic control device 50 at predetermined intervals.

  When this process is started, first, the engine speed NE is read (S300), and it is determined whether or not the current engine speed NE is a low speed (S310). In step S310, when the engine speed NE is lower than a low rotation determination value NEa (for example, 2000 r / min), it is determined that the rotation is low.

  If the current engine speed NE is low (S310: YES), the cutoff frequency Fc is set to the third frequency Fc3 as shown in FIG. 11 (S320), and this process is temporarily terminated. The

  The third frequency Fc3 is set to a frequency (for example, Fc3 = Fc2 × 1.2) higher than the second frequency Fc2, which is a preset reference frequency, and the third frequency Fc3 is set. Thus, the responsiveness of the estimated displacement amount Xs is prioritized over the noise reduction effect in the observer. The second frequency Fc2 is set to an optimum value when the cut-off frequency Fc is variably set according to the engine speed.

  On the other hand, if the current engine speed NE is not low (S310: NO), it is determined whether or not the current engine speed NE is high (S330). In step S330, when the engine speed NE is higher than a high rotation determination value NEb (for example, 4000 r / min), it is determined that the engine is rotating at high speed.

  When the current engine speed NE is high (S330: YES), as shown in FIG. 11, the cut-off frequency Fc is set to the first frequency Fc1 (S340), and this process is temporarily terminated. The

  The first frequency Fc1 is set to a frequency lower than the second frequency Fc2 (for example, Fc1 = Fc2 × 0.8). By setting the first frequency Fc1, the estimated displacement in the observer is set. The noise reduction effect is prioritized over the response of the quantity Xs.

  On the other hand, when the current engine speed NE is not high (S330: NO), as shown in FIG. 11, the cutoff frequency Fc is set to the second frequency Fc2 (S350), and this process is temporarily terminated. .

According to the present embodiment described above, the following operational effects can be obtained in addition to the operational effect of (1) described in the first embodiment.
(6) The lower the engine rotational speed NE, the lower the background noise and the more easily the operating sound of the valve body 19 can be heard. Therefore, in order to reduce the operating noise of the valve body 19, it is better to improve the responsiveness of the estimated displacement amount Xs through the observer as described in the seating mode. Therefore, in this embodiment, the lower the engine speed NE, the higher the cutoff frequency Fc, that is, priority is given to the responsiveness of the estimated displacement amount Xs over the noise reduction effect. Therefore, when the engine rotational speed NE is better to give priority to the response of the estimated displacement amount Xs in the observer, the response property of the estimated displacement amount Xs can be improved with certainty. The 19 operating sounds can be suitably reduced.

  On the other hand, when the determination process for determining whether or not the valve body 19 is reliably displaced to the displacement end, that is, whether or not the valve body 19 is operating normally, the estimated displacement amount Xs (valve By performing the determination based on the displacement state of the valve body 19 after a predetermined period of time estimated based on the current displacement state of the body 19, it is possible to detect an abnormal operation of the valve body 19 at an early stage. . Here, if an abnormal operation of the valve body 19 occurs in a high rotational speed range, it greatly affects the engine operating state and emission. Therefore, it is desirable to particularly improve the abnormality determination accuracy in such a rotational speed range. In this respect, according to the present embodiment, the cutoff frequency Fc is set to be higher as the engine speed NE is lower, and conversely, the cutoff frequency Fc is set to be lower as the engine speed NE is higher. Is done. For this reason, the noise reduction effect is given priority in the higher rotation speed region, and thus the observer estimation accuracy, that is, the estimation accuracy of the estimated displacement amount Xs with respect to the actual value of the displacement amount X is increased. Therefore, at an engine rotation speed where it is better to give priority to the noise reduction effect, the noise reduction effect can be improved with certainty. As a result, when performing abnormality determination as described above, the determination accuracy can be improved. become able to.

In addition, this embodiment can also be changed and implemented as follows.
In the above embodiment, as shown in FIG. 11, the cutoff frequency Fc is changed stepwise based on the engine rotational speed NE. In addition, as shown in FIG. 12, the cutoff frequency Fc may be continuously changed based on the engine rotational speed NE so that the cutoff frequency Fc becomes higher as the engine rotational speed NE is lower. In this case, the correspondence between the engine speed NE and the cut-off frequency Fc as shown in FIG. 12 is set with a map or a function expression, and the map or function expression is electronically controlled. It is stored in the memory of the device 50. Then, by setting the cut-off frequency Fc based on the engine speed NE and the same map or the same function expression, the operational effects of the above embodiment can be further enhanced. Incidentally, when setting a function formula, a linear formula, a high-order formula, an exponential function, a logarithmic function, or the like can be used so that the cutoff frequency corresponding to the engine speed is set appropriately.
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described focusing on the differences from the first embodiment.

  In the first embodiment, the cutoff frequency Fc is variably set based on the noise level, but in this embodiment, the cutoff frequency Fc is variably set based on the engine load.

  FIG. 13 shows the procedure of the cutoff frequency setting process in this embodiment. FIG. 14 shows how the cut-off frequency Fc is set in the cut-off frequency setting process. This process is repeatedly executed by the electronic control device 50 at predetermined intervals.

  When this process is started, the load factor KL is first read (S400). This load factor KL is the ratio of the current accelerator operation amount ACCP to the maximum value of the operable accelerator operation amount, the ratio of the current throttle opening TA to the maximum opening of the throttle valve, or the fuel injection amount at full load It is calculated based on the ratio of the current fuel injection amount.

  Then, it is determined whether or not the current load factor KL is in a high load region (S410). In step S410, when the load factor KL is higher than a high load determination value KLb (for example, 60%), it is determined that the load region is a high load region.

  If the current load factor KL is in the high load region (S410: YES), as shown in FIG. 14, the cutoff frequency Fc is set to the first frequency Fc1 (S420), and this process is temporarily terminated. The

  The first frequency Fc1 is set to a frequency (for example, Fc1 = Fc2 × 0.8) lower than the second frequency Fc2, which is a preset reference frequency, and the first frequency Fc1 is set. Thus, the noise reduction effect is prioritized over the responsiveness of the estimated displacement amount Xs in the observer. The second frequency Fc2 is set to an optimum value when the cut-off frequency Fc is variably set according to the engine load.

  On the other hand, when the current load factor KL is not in the high load region (S410: NO), it is determined whether or not the current load factor KL is in the low load region (S430). In this step S430, when the load factor KL is lower than the low load determination value KLa (for example, 30%), it is determined that it is a low load region.

  When the current load factor KL is in the low load region (S430: YES), as shown in FIG. 14, the cutoff frequency Fc is set to the third frequency Fc3 (S440), and this process is temporarily terminated. The

  The third frequency Fc3 is set to a frequency higher than the second frequency Fc2 (for example, Fc3 = Fc2 × 1.2). By setting the third frequency Fc3, noise reduction in the observer is performed. The responsiveness of the estimated displacement amount Xs is prioritized over the effect.

  On the other hand, when the current load factor KL is not in the low load region (S430: NO), as shown in FIG. 14, the cutoff frequency Fc is set to the second frequency Fc2 (S450), and this process is temporarily terminated. .

According to the present embodiment described above, the following operational effects can be obtained in addition to the operational effect of (1) described in the first embodiment.
(7) Various external forces such as in-cylinder pressure and exhaust pressure act on the valve body 19, and the influence of the external force on the operation of the valve body 19 increases as the engine load increases. Therefore, the control of the displacement state of the valve body 19, in other words, the control of the electromagnets 61 and 62 becomes more difficult due to such disturbance factors as the engine load increases. Therefore, as the engine load is higher, the noise reduction effect is prioritized over the responsiveness of the estimated displacement amount Xs to increase the estimation accuracy of the estimated displacement amount Xs by the observer, and the displacement state of the valve element 19 is more accurately grasped. It is desirable to do so. Therefore, in the above embodiment, the higher the engine load (load factor KL), the lower the cut-off frequency Fc, in other words, the higher the engine load, the higher the noise reduction effect. Therefore, in the engine load state where it is better to give priority to the noise reduction effect, the noise reduction effect can be improved reliably, and the displacement state of the valve body 19 can be estimated with high accuracy. Therefore, the controllability of the electromagnets 61 and 62 can be improved even in a state where the influence of disturbance factors on the operation of the valve body 19 becomes large.

In addition, this embodiment can also be changed and implemented as follows.
In the above embodiment, as shown in FIG. 14, the cut-off frequency Fc is changed stepwise based on the load factor KL. In addition, as shown in FIG. 15, the cutoff frequency Fc may be continuously changed based on the load factor KL so that the higher the load factor KL, the lower the cutoff frequency Fc. In this case, the correspondence relationship between the load factor KL and the cut-off frequency Fc as shown in FIG. 15 is set with a map or a function equation, and the map or the function equation is set to the electronic control unit. It is stored in 50 memories. Then, by setting the cut-off frequency Fc based on the load factor KL and the map or the function equation, the operational effects of the above embodiment can be further enhanced. Incidentally, when setting a function expression, a linear expression, a high-order expression, an exponential function, a logarithmic function, or the like can be used so that a cutoff frequency corresponding to the engine load is appropriately set.
(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described focusing on the differences from the first embodiment.

  In the first embodiment, the cutoff frequency Fc is variably set based on the noise level. However, in this embodiment, the cutoff frequency Fc is variably set by controlling the exhaust valve 10 and the intake valve. I am doing so.

  FIG. 16 shows the procedure of the cut-off frequency setting process in the present embodiment. FIG. 17 shows how the cutoff frequency Fc is set in the cutoff frequency setting process. This process is repeatedly executed by the electronic control device 50 at predetermined intervals.

When this process is started, it is first determined whether or not the intake valve control is being performed, that is, whether or not the current control target of the electromagnetically driven valve is the intake valve (S500).
If the intake valve control is being performed (S500: YES), as shown in FIG. 17, the cutoff frequency Fc is set to the intake valve frequency Fcin (S510), and this process is temporarily terminated. The intake valve frequency Fcin is set to be higher than the exhaust valve frequency Fex, and by setting the intake valve frequency Fcin, the response of the estimated displacement amount Xs is more than the noise reduction effect in the observer. Is preferred.

  On the other hand, when the intake valve control is not performed, in other words, when the exhaust valve control is performed (S500: NO), the cutoff frequency Fc is set to the exhaust valve frequency Fex as shown in FIG. (S520), and this process is temporarily terminated. As described above, the exhaust valve frequency Fcex is set to a frequency lower than the intake valve frequency Fcin. By setting the exhaust valve frequency Fcex, the response of the estimated displacement amount Xs in the observer is set. The noise reduction effect is given priority over.

According to the present embodiment described above, the following operational effects can be obtained in addition to the operational effect of (1) described in the first embodiment.
(8) Since a relatively large external force such as in-cylinder pressure acts on the exhaust valve 10, the control of the displacement state of the exhaust valve 10, in other words, the control of the electromagnet on the exhaust valve 10 side, is compared with the intake valve side. It becomes difficult due to such disturbance factors. Therefore, as described in the fourth embodiment, in a state where such control is difficult due to a disturbance factor, the noise reduction effect is prioritized over the response of the estimated displacement amount Xs, and the estimated displacement amount Xs by the observer is reduced. It is desirable to increase the estimation accuracy and grasp the displacement state of the valve body 19 more accurately. Therefore, in the present embodiment, when the valve body 19 to be controlled is the exhaust valve 10, the cutoff frequency Fc is made lower than when the valve body 19 to be controlled is an intake valve. . That is, the noise reduction effect is prioritized in the control on the exhaust valve 10 side as compared with the control on the intake valve side. Therefore, it is possible to reliably improve the noise reduction effect with respect to the control of the exhaust valve 10 in which priority should be given to the noise reduction effect, so that the displacement state of the valve body 19 can be accurately estimated. become. Therefore, it becomes possible to improve the controllability of the electromagnets 61 and 62 on the exhaust valve 10 side that are easily affected by disturbance factors.

In addition, this embodiment can also be changed and implemented as follows.
When the control of the exhaust valve 10 and the control of the intake valve are controlled by separate control devices, the observer cutoff frequency Fc set in the control device on the exhaust valve 10 side is supplied to the control device on the intake valve side. It may be set in advance lower than the set cutoff frequency Fc of the observer.

Moreover, each said embodiment can also be changed and implemented as follows.
In each of the above embodiments, the voltage noise VN of the displacement sensor 52 is calculated. Such voltage noise VN may gradually increase as shown in FIG. 18 due to the change in output characteristics due to the progress of aging of the displacement sensor 52 or the secular change of the detection unit. When the voltage noise VN increases excessively, it is difficult to control the electromagnets 61 and 62, and there is a possibility that a negative effect such as a reduction in the operation noise reduction effect by the operation noise reduction control may occur. Further, if the increase in the voltage noise VN proceeds excessively, the electromagnets 61 and 62 may step out, which may cause problems such as difficulty in feedback control. Therefore, when the noise level such as the voltage noise VN exceeds a preset threshold value, a determination process for determining that the displacement sensor 52 is abnormal may be executed. The threshold value in this case is a value that can be used to determine that the noise level has become so large that the operating noise cannot be suppressed, or the closed drive electromagnet 61 and the open drive electromagnet 62 are stepped out. It is possible to set a value or the like that can be used to determine that the noise level has increased as much as possible.

  When the abnormality of the displacement amount sensor 52 is detected in this way, the abnormality is stored in the diagnosis or the abnormality detection lamp is turned on to prompt replacement of the displacement amount sensor 52. The operating noise of the valve body 19 and the controllability of the electromagnets 61 and 62 can be kept good.

The first to fifth embodiments can be implemented in combination as appropriate. For example, the following combinations (1) to (26) can be implemented.
(1) Combining the first and second embodiments, the cut-off frequency Fc set based on the valve operating region is further variably set according to the noise level.

(2) By combining the first and third embodiments, the cut-off frequency Fc set based on the engine speed is further variably set according to the noise level.
(3) The cut-off frequency Fc set based on the engine load is further variably set according to the noise level by combining the first and fourth embodiments.

(4) By combining the first and fifth embodiments, the cut-off frequency Fc set according to the exhaust valve control or the intake valve control is further variably set according to the noise level.
(5) By combining the second and third embodiments, the cut-off frequency Fc set based on the operating region of the valve body is further variably set according to the engine speed.

(6) By combining the second and fourth embodiments, the cut-off frequency Fc set based on the valve operating region is further variably set according to the engine load.
(7) By combining the second and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further variably set according to the operating region of the valve body.

(8) By combining the third and fourth embodiments, the cut-off frequency Fc set based on the engine speed is further variably set according to the engine load.
(9) By combining the third and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further variably set according to the engine speed.

(10) By combining the fourth and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further variably set according to the engine load.
(11) By combining the first, second, and third embodiments, the cut-off frequency Fc set based on the operating region of the valve body is further variably set according to the engine speed and the noise level.

  (12) By combining the first, second, and fourth embodiments, the cutoff frequency Fc set based on the operating region of the valve body is further variably set according to the engine load and the noise level.

  (13) Combining the first, second, and fifth embodiments, the cut-off frequency Fc set according to the exhaust valve control and the intake valve control is further variably set according to the operating region of the valve body and the noise level. To do.

  (14) The first, third, and fourth embodiments are combined to set the cutoff frequency Fc based on the engine rotation speed and the engine load, and the set cutoff frequency is further set according to the noise level. Variable setting.

  (15) By combining the first, third, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control and the intake valve control is further variably set according to the engine speed and the noise level.

  (16) The cut-off frequency Fc set according to the exhaust valve control or the intake valve control is further variably set according to the engine load and the noise level by combining the first, fourth and fifth embodiments.

  (17) Combining the second, third, and fourth embodiments, the cut-off frequency Fc set based on the operating region of the valve body is further variably set according to the engine speed and the engine load.

  (18) Combining the second, third, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control and the intake valve control is further variable according to the operating region of the valve body and the engine speed. Set.

  (19) Combining the second, fourth and fifth embodiments, the cut-off frequency Fc set according to the exhaust valve control and the intake valve control is further variably set according to the operating region of the valve body and the engine load. To do.

  (20) Combining the third, fourth, and fifth embodiments, the cut-off frequency Fc set according to the exhaust valve control and the intake valve control is further variably set according to the engine speed and the engine load.

  (21) Combining the first, second, third, and fourth embodiments, the cutoff frequency Fc set based on the operating region of the valve body is further set according to the engine speed, the engine load, and the noise level. Variable setting.

  (22) Combining the first, second, third, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further set to the operating region of the valve body, the engine rotational speed, and Variable setting according to the noise level.

  (23) By combining the first, second, fourth, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further set, and the valve operating region, engine load, and noise Variable setting according to the level.

  (24) By combining the first, third, fourth, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further set to the engine speed, the engine load, and the noise level. Set the variable accordingly.

  (25) Combining the second, third, fourth, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control and the intake valve control is further set to the operating region of the valve body, the engine speed, and Variable setting according to engine load.

  (26) By combining the first, second, third, fourth, and fifth embodiments, the cutoff frequency Fc set according to the exhaust valve control or the intake valve control is further set to the operating region of the valve body and the engine Variable setting is made according to the rotational speed, engine load and noise level.

  As described above, when the first to fifth embodiments are appropriately combined and implemented, the effects according to the combination can be obtained. As a result, the cutoff frequency of the observer can be set more appropriately, and the control accuracy of the electromagnet can be further improved.

  In each of the above embodiments, a holding current is supplied to each of the electromagnets 61 and 62 during a period in which the valve body 19 is held at its displacement end (fully opened position or fully closed position), and electromagnetic force generated by the supply of this holding current is used. The valve body 19 is held in the fully closed position or the fully open position. In addition, for example, permanent magnets may be provided in the cores 32 and 34 of the electromagnets 61 and 62, respectively, and the valve body 19 may be held in the fully closed position or the fully open position by the magnetic force of these permanent magnets. In this case, a magnetic flux in the direction opposite to the magnetic flux of the permanent magnet is generated in each electromagnet 61 and 62, and the magnetic flux of the permanent magnet is canceled out, so that the valve body is moved from one displacement end. It can be displaced to the other displacement end.

  In each of the above embodiments, the intake valve and the exhaust valve of the internal combustion engine are each configured as an electromagnetically driven valve. In addition, the control device for the electromagnetically driven valve according to the first to fourth embodiments, the modified examples thereof, or the combination of these embodiments is configured such that only the intake valve or only the exhaust valve is configured as an electromagnetically driven valve. It can be applied in the same way. Moreover, the control device for the electromagnetically driven valve according to the first to fourth embodiments, the modified examples thereof, or the combination of these embodiments is provided when the intake valve and the exhaust valve are respectively configured as electromagnetically driven valves. The present invention may be applied only to the control device for the electromagnetically driven valve on the intake valve side or to the control device for the electromagnetically driven valve on the exhaust valve side.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the structure of the exhaust valve to which this is applied about 1st Embodiment which actualized the control apparatus of the electromagnetically driven valve concerning this invention. The timing chart which shows the control aspect of the electromagnetically driven valve in the embodiment. The conceptual diagram which shows the influence of the cutoff frequency with respect to the responsiveness of the estimated value in an observer, and the noise reduction effect. The flowchart which shows the procedure of the cutoff frequency setting process in the embodiment. The graph which shows the setting tendency of the cutoff frequency in the embodiment. The graph which shows the effect of the cutoff frequency setting process performed in the embodiment. The flowchart which shows the procedure of the cut-off frequency setting process in 2nd Embodiment. In the same embodiment, the corresponding figure which shows the cutoff frequency corresponding to the operation mode of a valve body. The timing chart which shows those temporal transition about the cut-off frequency and the displacement amount of a valve body which are set corresponding to the operation mode of a valve body. The flowchart which shows the procedure of the cut-off frequency setting process in 3rd Embodiment. The graph which shows the setting tendency of the cutoff frequency in the embodiment. The graph which shows the setting tendency of the cut-off frequency in the modification of the embodiment. The flowchart which shows the procedure of the cutoff frequency setting process in 4th Embodiment. The graph which shows the setting tendency of the cutoff frequency in the embodiment. The graph which shows the setting tendency of the cut-off frequency in the modification of the embodiment. The flowchart which shows the procedure of the cutoff frequency setting process in 5th Embodiment. The graph which shows the setting aspect of the cutoff frequency in the same embodiment. The time chart which shows time transition of voltage noise in the modification with respect to each embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Exhaust valve, 12 ... Combustion chamber, 14 ... Exhaust port, 15 ... Valve seat, 16 ... Umbrella part, 18 ... Cylinder head, 19 ... Valve body, 20 ... Valve shaft, 21 ... Electromagnetic drive part, 22 ... Lower retainer, 24 ... Lower spring, 26 ... Armature shaft, 28 ... Armature, 30 ... Upper partition, 32 ... Upper core, 34 ... Lower core, 36 ... Upper cap, 38 ... Upper spring, 40 ... Groove, 42 ... Upper coil, 44 ... Groove, 46 DESCRIPTION OF SYMBOLS ... Lower coil, 50 ... Electronic control unit, 52 ... Displacement amount sensor, 61 ... Electromagnet for closed drive, 62 ... Electromagnet for open drive.

Claims (10)

An apparatus for controlling the driving of an electromagnetically driven valve that opens and closes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine by an electromagnetic force of an electromagnet, and a sensor that detects a displacement state of the valve body, An observer for estimating a displacement state of the valve body after a predetermined period of time has elapsed since the detection of the displacement state, and for controlling the electromagnetic force based on the estimated displacement state,
A control device for an electromagnetically driven valve, comprising variable means for varying a cutoff frequency of the observer. The variable means includes noise calculation means for calculating a noise level to be superimposed on the detection signal of the sensor, and sets the cutoff frequency so that the cutoff frequency becomes lower as the calculated noise level becomes larger. The control device of the electromagnetically driven valve according to claim 1. In the control device of the electromagnetically driven valve according to claim 2,
A control device for an electromagnetically driven valve, comprising: a determination unit that determines that the sensor is abnormal when the calculated noise level exceeds a preset threshold value. The control device for an electromagnetically driven valve according to claim 1, wherein the variable means variably sets the cut-off frequency according to an operation region of the valve body. In the control device of the electromagnetically driven valve according to claim 4,
It is set in at least one of an operation region in which the valve body is held at the displacement end and an operation region in which power supply to the electromagnet is stopped in the process in which the valve body is displaced from one displacement end to the other displacement end. The electromagnetically driven valve control device is characterized in that the cut-off frequency is set to be lower than in other operation regions. In the control device of the electromagnetically driven valve according to claim 4 or 5,
The control device for an electromagnetically driven valve, wherein the cut-off frequency set in an operation region immediately before the valve body reaches its displacement end is set to be higher than in other operation regions. The control device for an electromagnetically driven valve according to claim 1, wherein the variable means sets the cutoff frequency so that the cutoff frequency becomes higher as the engine speed is lower. The control device for an electromagnetically driven valve according to claim 1, wherein the variable means sets the cutoff frequency so that the cutoff frequency becomes lower as the engine load is higher. An apparatus for controlling the driving of an electromagnetically driven valve that opens and closes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine by an electromagnetic force of an electromagnet, and a sensor that detects a displacement state of the valve body, An observer for estimating a displacement state of the valve body after a predetermined period of time has elapsed since the detection of the displacement state, and for controlling the electromagnetic force based on the estimated displacement state,
When the valve body is an exhaust valve, the cut-off frequency is set so that the cut-off frequency of the observer is lower than that when the valve body is an intake valve. Drive valve control device. In the control apparatus of the electromagnetically driven valve according to any one of claims 4 to 9,
A noise calculating means for calculating a noise level to be superimposed on the detection signal of the sensor; and a determining means for determining that the sensor is abnormal when the calculated noise level exceeds a preset threshold value. A control device for an electromagnetically driven valve.

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