JP5348014B2 - Variable valve system - Google Patents

Description

  The present invention relates to a variable valve system that can vary valve characteristic values of an engine valve such as valve timing, valve lift, and working angle.

  As is well known, a variable valve system that varies the valve characteristics of an engine valve (suction / exhaust valve) is mounted on many on-board internal combustion engines. Examples of such a variable valve system include a system that makes the valve timing of the engine valve variable, and a system that makes the lift amount and operating angle of the engine valve variable.

  In an internal combustion engine equipped with such a variable valve system, interference between the engine valve and the piston, so-called valve stamp, may occur depending on the setting of the valve characteristic value. For example, the valve stamp may be generated by changing the valve timing so that the lift center of the engine valve approaches the top dead center of the piston, or by increasing the lift amount or operating angle of the engine valve. Therefore, in such a variable valve system, the valve stamp is avoided by guarding (limiting) the variable range of the valve characteristic value within a range where the valve stamp can be reliably avoided.

  In some variable valve systems, the valve characteristic value is variable by driving the variable valve mechanism with an electric actuator. In addition, a variable valve system that grasps the current valve characteristic value from the operation amount of the actuator and performs variable control of the valve characteristic value has been put into practical use. For example, there is a system that obtains a current valve characteristic value by installing a position sensor that generates a pulse each time an actuator rotates by a predetermined angle, and counting the pulses of the position sensor.

  In such a variable valve system, when a so-called momentary interruption occurs in which the voltage applied to the actuator drops momentarily, drive control of the actuator is temporarily disabled. During this time, the operating position of the actuator may be displaced and the valve characteristic value may change due to mechanical rattling, reaction force of the valve spring that drives the engine valve, inertia, or the like. However, since the operating position of the actuator cannot be confirmed during the instantaneous interruption, the magnitude of the deviation of the valve characteristic value that occurred during the instantaneous interruption cannot be detected. Therefore, when a momentary interruption occurs, the current valve characteristic value may become unknown, and it may become impossible to suitably control the valve characteristic value so as to avoid the valve stamp.

  Therefore, conventionally, as can be seen in Patent Document 1, if the time of instantaneous interruption is measured and the time is equal to or greater than the determination value, the valve characteristic value during the instantaneous interruption is impossible until good valve characteristic control cannot be continued. There has been proposed a variable valve system that determines that the deviation is large. Note that, in the variable valve system described in Patent Document 1, the determination value used for the determination is set to a smaller value as the engine rotational speed is higher.

JP 2008-223705 A

  Such a conventional variable valve system estimates the deviation of the valve characteristic value during the momentary interruption, using the engine speed at the momentary interruption and the time of the momentary interruption as parameters. However, factors affecting the deviation of the valve characteristic value during the instantaneous interruption exist in addition to the engine speed and the instantaneous interruption time, and there is still room for improvement in improving the estimation accuracy.

  The present invention has been made in view of such circumstances, and the problem to be solved is to provide a variable valve system that can more accurately estimate the deviation of the valve characteristic value during instantaneous interruption. is there.

  The invention according to claim 1 includes a variable valve mechanism that makes the valve characteristic value of the engine valve variable, and an electric actuator that drives the variable valve mechanism, and the current amount of the actuator is determined based on the operation amount of the actuator. A variable valve system that performs valve characteristic variable control of the engine valve by calculating a valve characteristic value is presupposed. In such a variable valve system, a valve characteristic value to be subjected to variable control is not directly detected, but is calculated from an operation amount of the actuator. In such a variable valve system, when the actuator is momentarily interrupted and the input of the operation amount information from the actuator is interrupted, the change in the valve characteristic value during that time cannot be grasped. In such a case, there is a discrepancy between the valve characteristic value grasped by the control system and its actual value, so that the valve characteristic value may be erroneously changed to the generation region of the valve stamp, and the valve stamp may be generated. There is.

  During the momentary interruption, the operating position of the actuator is displaced by the inertia of the previous operation. The magnitude of the inertia acting on the actuator during the momentary interruption can be grasped from the operating speed of the actuator before the momentary interruption. In view of this, the invention according to claim 1 is provided with an estimation means for estimating the amount of deviation of the valve characteristic value during the instantaneous interruption from the operating speed of the actuator before the occurrence of the instantaneous interruption of the energization of the actuator. I have to. Based on the operating speed of the actuator before the momentary interruption, it is possible to estimate the magnitude of the displacement of the actuator operating position due to the inertia during the momentary interruption, and thus the amount of deviation of the valve characteristic value due to the inertia during the momentary interruption. Therefore, according to the above configuration, it is possible to more accurately estimate the deviation of the valve characteristic value during instantaneous interruption in consideration of inertia.

The operating speed of the actuator during normal operation varies depending on the reaction force of the cam and noise. Therefore, just looking at the instantaneous value of the operating speed of the actuator before the momentary interruption, the movement speed may temporarily take a small value due to such fluctuations, and the magnitude of inertia acting on the actuator during the momentary interruption May be underestimated. In this regard, in the first aspect of the invention, an average value of the operating speed for a predetermined period and an instantaneous value of the operating speed are obtained for the operating speed of the actuator before the occurrence of the momentary interruption, and among these two values, The estimation means is configured to estimate the amount of deviation using the larger value . That is, in the configuration according to the first aspect , the deviation amount of the valve characteristic value is estimated using an operation speed with a higher risk of valve stamp. For this reason, according to the first aspect of the present invention, it is possible to more reliably avoid the occurrence of the valve stamp due to the deviation of the valve characteristic value during the momentary interruption.

Here, according to claim 2, when the deviation amount estimated by the estimation means is equal to or greater than a predetermined abnormality determination value, the variable valve system includes a determination means that determines that there is an abnormality. If the deviation of the valve characteristic value during momentary interruption is large and the difference between the valve characteristic value grasped by the control system and its actual value is large, it is judged that the variable valve system is abnormal, for example, notification of abnormality or saving It is possible to take measures for avoiding the valve stamp such as shifting to the traveling mode.

In addition, when the operation direction of the actuator before the momentary interruption is a direction in which valve stamps are less likely to occur, for example, the valve timing has been changed so that the lift center of the engine valve is away from the top dead center of the piston, When the lift amount and operating angle of the engine valve are reduced, even if the deviation of the valve characteristic value during the momentary interruption is large, the valve stamp does not occur. Therefore, according to claim 3 , if the determination means is configured to determine that there is an abnormality on the condition that the operation direction of the actuator before the momentary interruption is a direction in which a valve stamp is more likely to occur, Only when there is actually a risk of occurrence of a valve stamp, an abnormality determination is made.

Note that the deviation of the valve characteristic value during instantaneous interruption tends to increase as the instantaneous interruption time increases. Further, when the instantaneous interruption time is long, uncertain factors increase, and it becomes difficult to estimate the magnitude of the deviation of the valve characteristic value during the instantaneous interruption with sufficient accuracy. Therefore, as described in claim 4 , when the instantaneous interruption time is equal to or greater than the predetermined value, it is possible to immediately determine that there is an abnormality without depending on the estimation result of the deviation amount. It becomes possible to further reduce the risk of occurrence of valve stamps.

As described above, it is possible to avoid the valve stamp if it is determined that there is an abnormality when the estimated value of the deviation amount of the valve characteristic value during the instantaneous interruption is large. However, even when the estimated value of the deviation of the valve characteristic value during momentary interruption is not so large, there may be a certain divergence between the valve characteristic value grasped by the control system and its actual value. Depending on how the valve characteristic value is controlled, a valve stamp may occur. Even in such a case, as in claim 5, when the deviation estimated by the estimating means is less than the predetermined abnormality determination value, the guard range of the valve characteristic value is expanded more than usual and variable control of the valve characteristic value is performed. If the operation is continued, the occurrence of a valve stamp can be avoided more reliably. If the guard range is expanded by offsetting the guard range by the estimated amount of deviation by the estimating means as in claim 6 , the valve stamp can be avoided more suitably. Will be able to.

By the way, the ease of movement of the actuator due to the inertia during momentary interruption is influenced by the friction of the actuator, the operating position of the actuator, the mobility, the reaction force of the cam, the inertial mass of the valve system, and the like. It is considered that the ease of movement of the actuator during such momentary interruption correlates with the engine speed. Specifically, it is considered that the higher the engine speed, the easier the actuator during momentary interruption due to inertia. Therefore, as described in claim 7 , if the engine rotational speed is also taken into consideration in the estimation of the deviation amount of the estimation means, the deviation of the valve characteristic value during the momentary interruption can be estimated more accurately.

The schematic diagram which shows typically the whole structure of the variable valve system about one Embodiment of this invention. Sectional drawing which shows the side part sectional structure of the valve operating system of the internal combustion engine in which the variable valve operating system of the embodiment was installed. Sectional drawing which shows the perspective sectional structure of the variable valve mechanism which the variable valve system of the embodiment employ | adopts. Sectional drawing which shows the perspective sectional structure of the input arm and output arm of the variable valve mechanism. The graph which shows transition of the operation amount of the actuator in operation angle expansion in the variable valve system of the embodiment. The graph which shows the relationship between the operation position of the actuator in the variable valve system of the embodiment, and the shift | offset | difference of the working angle during instantaneous interruption. The graph which shows the relationship between the engine rotational speed in the variable valve system of the embodiment, and the shift | offset | difference of the working angle during instantaneous interruption. The graph which shows the relationship between the coefficient used for estimation of the deviation | shift amount of the working angle in the variable valve system of the embodiment, and instantaneous interruption time. The graph which shows the setting aspect of the working angle guard range before and behind the momentary interruption in the variable valve system of the embodiment. The flowchart which showed the process sequence of the processing routine at the time of a momentary interruption employ | adopted as the variable valve system of the embodiment.

(First embodiment)
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment embodying a variable valve system of the present invention will be described in detail with reference to FIGS. Note that the variable valve system of the present embodiment is configured as a system in which the working angle and lift amount of the intake valve are variable as valve characteristic values.

  FIG. 1 shows the overall configuration of the variable valve system according to this embodiment. As shown in the figure, this variable valve system includes a variable valve mechanism 1 that varies the operating angle and lift amount of an intake valve, and an actuator 2 that drives the variable valve mechanism 1. The actuator 2 includes a motor 200, a conversion mechanism 201 that converts rotation of the motor 200 into linear motion, a position sensor 202 that outputs a pulse signal each time the motor 200 rotates by a predetermined angle, and a drive circuit 203 that drives the motor 200. I have. The variable valve system is configured such that the control valve 3 is driven in the axial direction by the actuator 2 to operate the variable valve mechanism 1 so that the operating angle and the lift amount of the intake valve are variable. Yes.

  In the drive circuit 203 of the actuator 2, a comparison table of the operation amount of the actuator 2 (stroke of the control shaft 3) and the working angle of the intake valve is stored as data. Further, the drive circuit 203 obtains the current stroke (actual stroke) of the control shaft 3 and thus the current working angle (actual working angle) by counting the pulses generated by the position sensor 202.

  The actuator 2 is controlled by an electronic control unit 4 that performs various engine controls including variable control of the operating angle of the intake valve. The electronic control unit 4 calculates an optimum operating angle according to the engine operating condition and instructs the drive circuit 203 of the actuator 2.

  When receiving the operating angle command (operating angle command value) from the electronic control unit 4, the drive circuit 203 refers to the reference table and calculates the stroke of the control shaft 3 from which the operating angle command value is obtained as the target stroke. To do. Then, the drive circuit 203 sets the operating angle according to the command by rotating the motor 200 so that the actual stroke becomes the target stroke.

  FIG. 2 shows a configuration of a valve operating system of an internal combustion engine to which such a variable valve operating system is applied. As shown in the figure, the variable valve mechanism 1 is installed between a cam 6 provided on a camshaft 5 and an intake valve 10. The variable valve mechanism 1 is pivotally supported by a rocker shaft 7 disposed in parallel with the camshaft 5 and includes an input arm 100 and a pair of output arms 101 installed on both sides thereof. Yes. The control shaft 3 is slidably disposed in the axial direction inside the pipe-shaped rocker shaft 7.

  A roller 102 that is in contact with the cam 6 is rotatably attached to the tip of the input arm 100 of the variable valve mechanism 1. The input arm 100 is rocked integrally with the output arm 101 about the axis of the rocker shaft 7 in response to the depression by the cam 6.

  A protrusion 103 is formed on the outer periphery of the input arm 100. A lost motion spring 104 is disposed in a compressed state between the projection 103 and a spring seat 8 formed on the cylinder head of the internal combustion engine. The variable valve mechanism 1 is biased by the lost motion spring 104 so that the roller 102 of the input arm 100 is pressed against the cam 6.

  Roller rocker arms 9 are disposed below both output arms 101 of the variable valve mechanism 1. Each roller rocker arm 9 is swingably supported by the cylinder head of the internal combustion engine at its base end, and abuts against the upper end of the intake valve 10 at its tip end. Each roller rocker arm 9 is rotatably attached with a roller 11. The roller 11 is pressed against the cam surface 105 formed on the roller rocker arm 9 side at the tip of the output arm 101 by the spring force of the valve spring 12 of the intake valve 10.

  In such a valve operating system, when the variable valve operating mechanism 1 swings due to the cam 6 being pushed down by the rotation of the camshaft 5, the cam surface 105 of the output arm 101 presses the roller 11, thereby causing the roller rocker arm 9 to swing. To move. Then, the roller rocker arm 9 presses the upper end of the intake valve 10 at its tip according to its swinging, so that the intake valve 10 is driven to open and close. At this time, the contact point between the cam surface 105 of the output arm 101 and the roller 11 of the roller rocker arm 9 reciprocates along the cam surface 105 according to the swinging of the output arm 101. As the distance between the contact point between the cam surface 105 and the roller 11 and the rocker shaft 7 increases, the amount by which the roller rocker arm 9 is pushed down by the cam surface 105 and the lift amount of the intake valve 10 increases accordingly. .

  Further, in this valve operating system, the control shaft 3 is displaced in the axial direction inside the rocker shaft 7, so that the relative position between the tip of the input arm 100 and the tip of the output arm 101 in the swinging direction of the variable valve mechanism 1. It is possible to change. By changing the relative positions of the tips of the input arm 100 and the output arm 101, the reciprocating range of the contact point between the cam surface 105 and the roller 11 accompanying the swinging of the variable valve mechanism 1 is changed. The maximum lift amount and the operating angle of the valve are made variable.

  Specifically, the reciprocating movement range of the contact point between the cam surface 105 and the roller 11 increases as the tip of the input arm 100 and the tip of the output arm 101 approach each other in the swinging direction of the variable valve mechanism 1. As a result of displacement toward the shaft 7, the maximum lift amount and operating angle of the intake valve 10 are reduced accordingly. Further, as the tip of the input arm 100 and the tip of the output arm 101 are separated from each other in the swinging direction of the variable valve mechanism 1, the reciprocation range of the contact point is displaced in a direction away from the rocker shaft 7, and the intake valve The maximum lift amount and working angle of 10 are increased.

  Next, the internal structure of the variable valve mechanism 1 will be described with reference to FIGS. As shown in FIG. 3, a substantially cylindrical slider 106 is disposed inside the input arm 100 and the output arm 101 of the variable valve mechanism 1. The slider 106 is integral with the control shaft 3 and can move in the axial direction. An input gear 107 having a helical spline is fixed to the outer periphery of the slider 106 at the center in the longitudinal direction, and an output gear 108 having a helical spline is also fixed to both sides in the longitudinal direction.

  On the other hand, as shown in FIG. 4, an annular internal gear 109 having a helical spline is formed on the inner periphery of the input arm 100, and each output arm 101 also has a helical spline on the inner periphery. An annular internal gear 110 is formed. The internal gear 109 of the input arm 100 is engaged with the input gear 107 (FIG. 3) of the slider 106, and the internal gear 110 of each output arm 101 is engaged with the output gear 108 (FIG. 3) of the slider 106. Note that the helical splines of the input gear 107 and the internal gear 109 and the helical splines of the output gear 108 and the internal gear 110 have different inclination angles, and the inclination directions of the tooth traces are reversed.

  In such a valve operating system, when the slider 106 is displaced in the coaxial direction based on the movement of the control shaft 3 in the axial direction, the input gear 107 and the internal gear 109 are engaged, and the output gear 108 and the internal gear 110 are engaged. As a result, the relative position between the tip of the input arm 100 and the tips of the two output arms 101 in the swing direction of the variable valve mechanism 1 is changed. Specifically, as the slider 106 is displaced in the direction of the arrow L in FIG. 3, the relative position between the tip of the input arm 100 and the tips of the two output arms 101 in the swing direction is changed so as to approach each other. As the slider 106 is displaced in the direction of the arrow H, the relative positions are changed so as to be separated from each other. Through such a change in the relative position, the maximum lift amount and the operating angle of the intake valve 10 according to the swing of the variable valve mechanism 1 due to the rotation of the cam 6 can be made variable.

  In the internal combustion engine to which the present embodiment is applied, variable control of the valve timing of the intake valve 10 is performed in addition to variable control of the operating angle and lift amount by such a variable valve system. In such an internal combustion engine, when the valve timing of the intake valve 10 is advanced and the operating angle and the lift amount are increased to a certain extent with the lift center approaching the top dead center of the piston, the intake valve 10 and the piston of the internal combustion engine There is a risk that a so-called valve stamp may occur. Therefore, in the variable valve system of the present embodiment, the upper limit value of the variable range of the working angle is set according to the set value of the valve timing so that the valve stamp can be reliably avoided, that is, the working angle. The upper limit guard is performed.

  As described above, in the variable valve system configured as described above, the actual stroke and thus the actual working angle of the intake valve 10 are obtained by counting the pulses generated by the position sensor 202. In such a variable valve system, when the energization of the actuator 2 is momentarily interrupted, the output of the pulse signal of the position sensor 202 is interrupted, and thus the change in the operating angle of the intake valve 10 during that time cannot be confirmed. As a result, there is a divergence between the working angle of the drive circuit 203 and, consequently, the electronic control unit 4 and its actual value, and depending on the result of the subsequent working angle control, the working angle is unintentionally set to the valve stamp. There is a possibility that the valve stamp will be generated.

  The magnitude of the deviation of the operating angle during the momentary interruption affects the magnitude of the inertia acting on the actuator 2 during the momentary interruption, the ease of movement of the actuator 2 at that time, and the momentary interruption time. Here, the magnitude of the inertia acting on the actuator 2 at the moment of interruption can be obtained from the operating speed of the actuator 2 before the momentary interruption. Therefore, in the present embodiment, the amount of deviation of the operating angle during the instantaneous interruption is estimated in consideration of the operating speed of the actuator 2 before the occurrence of the instantaneous interruption (the change speed of the stroke of the control shaft 3).

  FIG. 5 shows a change in the operation amount (stroke of the control shaft 3) of the actuator 2 that is operating in the direction of expanding the operating angle. As shown in the figure, the operating speed of the actuator 2 varies (swells) due to changes in the cam reaction force. Therefore, the instantaneous value of the operating speed varies greatly depending on the timing of acquiring the operating speed. For example, when the instantaneous value of the operating speed is acquired at time t1 in the figure, the instantaneous value of the operating speed in the operating angle expansion direction is a small value. Therefore, if the amount of deviation of the working angle during the momentary interruption is calculated based on the value at this time, the amount of deviation is underestimated and the risk of the valve stamp cannot be sufficiently reduced.

  Therefore, in the present embodiment, when the instantaneous interruption occurs, the electronic control unit 4 obtains the average value of the operating speed of the actuator 2 before the instantaneous interruption in the predetermined period and the instantaneous value of the same operating speed. The electronic control unit 4 then sets the value of the two values that make the working angle closer to the side where the valve stamp is likely to occur, that is, the value on the higher operating speed in the direction of expanding the working angle, It is used to estimate the amount of deviation of the operating angle during a momentary interruption. In such a case, the operating angle shift amount during the momentary interruption is estimated using an operation speed with a higher risk of valve stamp. Therefore, it is possible to more reliably avoid the occurrence of a valve stamp due to a deviation of the valve characteristic value during a momentary interruption.

  On the other hand, the ease of movement of the actuator 2 during a momentary interruption is affected by the magnitude of friction of the actuator 2, the operating position of the actuator 2, the motility, the cam reaction force, the inertial mass of the valve system, and the like. FIG. 6 shows the relationship between the operating position of the actuator 2 and the magnitude of deviation of the operating angle during the momentary interruption when the length of the momentary interruption and the magnitude of the inertia acting on the actuator 2 during the momentary interruption are constant. Yes. In the figure, the above relationship is shown when the motility (ease of movement) of the actuator 2 is highest and lowest. As shown in the figure, even if the operating position of the actuator 2 is the same, there is a great difference in the amount of deviation of the operating angle during the momentary interruption.

  On the other hand, FIG. 7 shows the relationship between the engine speed when the momentary interruption length and the magnitude of the inertia acting on the actuator 2 during the momentary interruption are constant and the magnitude of the deviation of the operating angle during the momentary interruption. Show. In general, in an internal combustion engine, the operating position of the actuator 2 and its motility, the reaction force of the cam, the inertial mass of the valve system, and the like are designed and adapted so as to be synchronized with the engine rotational speed. Therefore, as shown in the figure, if the length of momentary interruption and the magnitude of inertia are the same, the magnitude of the deviation of the operating angle during momentary interruption due to inertia is uniquely determined by the engine speed. Become.

  Therefore, in this embodiment, when estimating the amount of deviation of the operating angle during the momentary interruption, an index value of the ease of movement of the actuator 2 at that time is obtained from the engine speed. Thus, by obtaining the index value of the ease of movement of the actuator 2 using the engine rotation speed as a parameter, it is possible to suppress estimation results and improve the estimation accuracy. In addition, it is possible to significantly reduce the man-hours required for creating the deviation estimation logic.

  The estimation of the amount of deviation of the operating angle during the momentary interruption in the present embodiment is specifically performed in the following manner. First, the electronic control unit 4 starts from the value of the higher speed in the direction in which the operating angle is expanded, of the average value of the operating speed of the actuator 2 before the instantaneous interruption and the instantaneous value of the same operating speed. The magnitude of inertia acting on the actuator 2 immediately after the momentary interruption is obtained. Further, the electronic control unit 4 obtains an index value of the ease of movement of the actuator 2 during a momentary interruption from the engine rotational speed at that time. Then, the electronic control unit 4 calculates, as an initial value, a deviation amount of the working angle in the unit time immediately after the instantaneous interruption from these values.

  The magnitude of the operating angle deviation per unit time due to inertia decreases with the passage of time due to deceleration due to friction or the like. Therefore, the electronic control unit 4 multiplies the initial value by a coefficient as shown in FIG. 8 that decreases from the value “1” as time elapses, thereby shifting the operating angle per unit time at each time during the instantaneous interruption. By calculating the amount and integrating the values for the momentary interruption period, an estimated value of the operating angle deviation amount in the entire instantaneous interruption period is calculated.

  The electronic control unit 4 determines that there is an abnormality in the variable valve system if the estimated amount of deviation of the operating angle is equal to or greater than the predetermined abnormality determination value α, and notifies the driver of the above by lighting the warning light. Transition to the evacuation travel mode. In this case, subsequent variable control of the operating angle is prohibited.

  On the other hand, in the present embodiment, when the estimated shift amount of the working angle is less than the predetermined abnormality determination value α, variable control of the working angle is continued. However, also in this case, there is a divergence between the working angle recognized by the electronic control unit 4 and its actual value due to the deviation during the instantaneous interruption. Therefore, in the present embodiment, as shown in FIG. 9, the upper limit guard line of the working angle corresponding to the valve timing, that is, the lower limit value of the guard range of the working angle is offset by the estimated deviation amount. In order to avoid the occurrence of valve stamps. Note that such an offset of the upper limit guard line is performed only when it is estimated that the operating angle has shifted in the direction of expanding the operating angle during the instantaneous interruption.

  Incidentally, the deviation of the operating angle during momentary interruption due to inertia increases as the momentary interruption time increases. Further, if the instantaneous interruption time becomes longer, the error of the estimated value of the operating angle deviation during the instantaneous interruption also increases. Therefore, in the present embodiment, when the instantaneous interruption time is equal to or greater than the predetermined value β, the electronic control unit 4 immediately determines that there is an abnormality without depending on the estimation result of the deviation amount as described above.

  FIG. 10 shows a flowchart of the instantaneous interruption processing routine employed in the present embodiment. The processing of this routine is repeatedly executed periodically by the electronic control unit 4 during engine operation.

  When this routine is started, it is first determined in step S100 whether or not an instantaneous interruption has occurred. If the occurrence of an instantaneous interruption is not confirmed here (S100: NO), the processing of this routine is terminated as it is.

  On the other hand, if an instantaneous interruption has occurred (S100: YES), it is determined in step S101 whether or not the instantaneous interruption time is equal to or greater than a predetermined value β. Here, if the instantaneous interruption time is equal to or greater than the predetermined value β (S101: YES), it is determined that there is an abnormality in the variable valve system at that time, and in step S102, the warning lamp is turned on or the shift to the evacuation travel mode is performed. The abnormal time processing is executed.

  When the instantaneous interruption time is less than the predetermined value β (S101: NO), the amount of operation angle deviation during the instantaneous interruption is estimated based on the operation speed of the actuator 2 before the instantaneous interruption in the manner described above in step S103. Is called. Then, in the subsequent step S104, it is determined whether or not the estimated shift amount of the operating angle is equal to or greater than the abnormality determination value α.

  If the amount of deviation of the operating angle estimated here is equal to or greater than the abnormality determination value α (S104: YES), whether or not the direction of deviation of the operating angle is a direction in which the operating angle is enlarged during the instantaneous interruption in step S105. Is determined. This determination is substantially synonymous with the determination of whether or not the operation direction of the actuator 2 before the momentary interruption is a direction in which the valve stamp is more likely to occur, that is, a direction in which the operating angle is expanded.

  If the operating angle deviates in the direction of expanding the operating angle during the momentary interruption (S105: YES), it is determined that the variable valve system is over, and in step S102, the warning lamp is turned on or Processing at the time of abnormality such as transition to the evacuation traveling mode is performed.

  On the other hand, whether the estimated deviation amount of the working angle is less than the abnormality determination value α (S104: NO), or even if the deviation amount is greater than or equal to the abnormality determination value α, the direction of the deviation is a direction that reduces the working angle If so (S105: NO), the process proceeds to step S106. In step S106, the operating angle upper limit guard line corresponding to the valve timing is offset by the estimated value of the deviation amount to expand the operating angle upper limit guard range, and the operating angle variable control is continued. Become so.

  In the present embodiment described above, the operating angle of the intake valve corresponds to the “valve characteristic value”. In the present embodiment, the electronic control unit 4 has a configuration corresponding to the “estimating means” and the “determining means”.

According to the variable valve system of the present embodiment as described above, the following effects can be obtained.
(1) The variable valve system according to the present embodiment includes a variable valve mechanism 1 that makes the operating angle of the intake valve 10 variable, and an electric actuator 2 that drives the variable valve mechanism 1, The present working angle is calculated from the amount of operation of the actuator 2, and the working angle of the intake valve 10 is variably controlled. In the present embodiment, in such a variable valve system, when an instantaneous interruption of energization of the actuator 2 occurs, the electronic control unit 4 determines the operating angle during the instantaneous interruption from the operating speed of the actuator 2 before the occurrence. The amount of deviation is estimated. Based on the operating speed of the actuator 2 before the momentary interruption, it is possible to estimate the displacement of the operating position of the actuator 2 due to the inertia during the momentary interruption and thus the amount of deviation of the operating angle due to the inertia during the momentary interruption. Become. Therefore, according to the present embodiment, it is possible to more accurately estimate the deviation of the valve characteristic value during instantaneous interruption in consideration of inertia.

  (2) In the present embodiment, the electronic control unit 4 is likely to generate a bubble stamp among the two values of the average value of the operating speed of the actuator 2 and the instantaneous value of the operating speed before the instantaneous interruption occurs. The amount of deviation is estimated using the value that makes the operating angle closer to the side. That is, in this embodiment, the amount of deviation of the valve characteristic value is estimated using an operation speed with a higher risk of valve stamp. Therefore, it is possible to more reliably avoid the occurrence of a valve stamp due to a deviation of the valve characteristic value during a momentary interruption.

  (3) In the present embodiment, the electronic control unit 4 determines that there is an abnormality in the variable valve system when the estimated shift amount of the operating angle is greater than or equal to a predetermined abnormality determination value α. . Therefore, if the deviation of the valve characteristic value during momentary interruption is large and the difference between the operating angle grasped by the control system and its actual value is large, it is judged that the variable valve system is abnormal, and notification or saving of abnormality is made. It is possible to take measures for avoiding the valve stamp such as shifting to the traveling mode.

  (4) In the present embodiment, it is determined that there is an abnormality when the estimated deviation amount of the operating angle is equal to or greater than the predetermined abnormality determination value α. It is performed only when the direction is less likely to occur, that is, the direction in which the operating angle is enlarged. Therefore, abnormality determination is made only when there is actually a risk of occurrence of a valve stamp, and an unnecessary increase in abnormality determination frequency is avoided.

  (5) In the present embodiment, when the instantaneous interruption time is equal to or greater than the predetermined value, it is determined immediately that there is an abnormality without depending on the estimation result of the deviation amount. The deviation of the valve characteristic value during instantaneous interruption tends to increase as the instantaneous interruption time increases. Further, when the instantaneous interruption time is long, uncertain factors increase, and it becomes difficult to estimate the magnitude of the deviation of the valve characteristic value during the instantaneous interruption with sufficient accuracy. Therefore, according to the present embodiment, it is possible to further reduce the risk of occurrence of a valve stamp due to a deviation of the valve characteristic value during instantaneous interruption.

  (6) In the present embodiment, when the estimated deviation amount is less than the abnormality determination value α, the guard range of the operating angle is expanded more than usual and the variable control of the valve characteristic value is continued. More specifically, the guard range of the operating angle is expanded by offsetting the guard range by the estimated deviation amount. Therefore, the variable control of the operating angle can be continued when the operating angle shift during the momentary interruption is small while avoiding the valve stamp.

  (7) In the present embodiment, the engine rotational speed is also taken into account in estimating the amount of deviation of the operating angle during the momentary interruption. The ease of movement of the actuator 2 due to inertia during momentary interruption is influenced by the friction of the actuator 2, the operating position of the actuator 2, the motility, the reaction force of the cam, the inertial mass of the valve system, and the like. The ease of movement of the actuator 2 during such instantaneous interruption correlates with the engine rotational speed. Therefore, according to the present embodiment, it is possible to more accurately estimate the deviation of the working angle during the instantaneous interruption.

The above embodiment can also be implemented with the following modifications.
In the above embodiment, the engine rotational speed is used for estimating the amount of deviation of the working angle during the momentary interruption. Of course, if the change according to the state of ease of movement of the actuator 2 during the momentary interruption is so small that it can be ignored, the engine speed is not taken into consideration, the momentary interruption time and the operating speed of the actuator 2 before the momentary interruption. Based on the above, it is also possible to estimate the amount of deviation of the operating angle during the momentary interruption.

  -In the above embodiment, when the amount of deviation of the working angle during the momentary interruption is less than the abnormality determination value α, the upper limit guard line that is the lower limit value of the guard range of the working angle is offset by the estimated deviation amount. The variable control of the working angle was continued after expanding the range. However, if it is desired to more reliably avoid the valve stamp, the upper limit guard line offset at this time may be set larger than the estimated value of the deviation amount. For example, if the upper limit guard line is offset by the maximum value of the deviation amount of the operating angle during an instantaneous interruption, it is possible to reliably avoid the valve stamp even if there is an error in the estimation of the deviation amount. It becomes like this.

  In the above embodiment, when the amount of deviation of the working angle during the momentary interruption is less than the abnormality determination value α, the working angle variable control is continued after expanding the guard range of the working angle. However, if the actual working angle used for the control is corrected according to the estimated amount of deviation and then the variable control of the working angle is continued, the valve stamp can be avoided without expanding the guard range. .

  In the above embodiment, when the instantaneous interruption time is equal to or greater than the predetermined value, it is determined that there is an abnormality immediately without depending on the estimation of the operating angle deviation during the instantaneous interruption. However, if the estimation accuracy of the deviation amount of the operating angle during the momentary interruption is sufficiently high, the presence / absence of abnormality may be determined based only on the estimation result of the deviation amount regardless of the momentary interruption time. .

  In the above embodiment, it is determined that there is an abnormality on the condition that the operation direction of the actuator 2 before the momentary interruption is a direction in which the valve stamp is more likely to occur. If the operation direction of the actuator 2 before the momentary interruption is a direction in which the valve stamp is less likely to occur, the operating angle is shifted in a direction in which the valve stamp is less likely to occur during the momentary interruption, and thus the amount of deviation is large. However, it does not lead to the occurrence of valve stamps. However, if the deviation of the working angle during a momentary interruption is large, there is a risk of hindering the subsequent variable control of the angle of action, so the direction of operation of the actuator 2 before the momentary interruption may cause more valve stamps. Even if the direction becomes difficult, it may be determined that there is an abnormality if the deviation of the working angle during the momentary interruption is large.

  In the embodiment described above, it is determined that there is an abnormality in the variable valve system when the estimated shift amount of the operating angle during the instantaneous interruption is equal to or greater than the abnormality determination value α. Even if the estimated operating angle deviation during a momentary interruption is large, if the variable control of the operating angle can be continued without generating a valve stamp due to expansion of the guard range, etc., the estimated amount of deviation will be increased. Regardless, the determination that there is an abnormality may not be performed.

  In the above embodiment, the operating angle is made closer to the side where the valve stamp is likely to occur, of the two values of the average value of the operating speed of the actuator 2 and the instantaneous value of the operating speed before the occurrence of the instantaneous interruption. The amount of deviation was estimated using the value of. However, if the fluctuation of the operating speed of the actuator 2 during operation is sufficiently small, the operating speed of the actuator 2 before the momentary interruption used for estimation is fixed to either the average value or the instantaneous value. Also good.

  In the above embodiment, the case where the present invention is applied to a variable valve system that makes the working angle and lift amount of the intake valve variable has been described. However, the present invention assumes that the working angle and lift amount of the exhaust valve are variable. The same can be applied to the variable valve system.

  In the above embodiment, a case has been described in which the present invention is applied to a variable valve system in which both the working angle and the lift amount of the engine valve are variable. However, the present invention is limited to only the working angle or the lift amount. The present invention can be similarly applied to a variable valve system that makes the variable.

  The present invention can also be applied to a variable valve system that varies the valve timing of the engine valve in a manner according to the above embodiment. Also in a variable valve system that includes an electric actuator that drives a variable valve mechanism that varies the valve timing of an engine valve, and that performs variable control of the valve timing by calculating the current valve timing from the amount of operation of the actuator If the power supply to the actuator is interrupted, the change in valve timing during that time cannot be confirmed. As a result, a divergence occurs between the valve timing grasped by the control system and the actual valve timing, and the same problem occurs in such a variable valve system. In such a variable valve timing system, a valve stamp may be generated by changing the valve timing so that the lift center of the engine valve approaches the top dead center of the piston. Specifically, when the valve timing of the intake valve is made variable, the advance side of the valve timing is a high side where the valve stamp is likely to occur, and when the valve timing of the exhaust valve is made variable, the valve timing is changed. The retard side is the side where valve stamps are likely to occur.

  DESCRIPTION OF SYMBOLS 1 ... Variable valve mechanism (100 ... Input arm, 101 ... Output arm, 102 ... Roller, 103 ... Protrusion, 104 ... Lost motion spring, 105 ... Cam surface, 106 ... Slider, 107 ... Input gear, 108 ... Output gear, 109 ... internal gear, 110 ... internal gear), 2 ... actuator (200 ... motor, 201 ... conversion mechanism, 202 ... position sensor, 203 ... drive circuit), 3 ... control shaft, 4 ... electronic control unit (estimating means) , Determination means), 5 ... cam shaft, 6 ... cam, 7 ... rocker shaft, 8 ... spring seat, 9 ... roller rocker arm, 10 ... intake valve, 11 ... roller, 12 ... valve spring.

Claims (7)

A variable valve mechanism that varies a valve characteristic value of the engine valve; and an electric actuator that drives the variable valve mechanism, and calculates the current valve characteristic value from an operation amount of the actuator to calculate the engine characteristic value In a variable valve system that performs variable control of valve characteristics,
When an instantaneous interruption of energization of the actuator occurs, the estimation means for estimating the amount of deviation of the valve characteristic value during the instantaneous interruption from the operating speed of the actuator before the occurrence ,
The estimation means obtains an average value and an instantaneous value of the same operating speed for a predetermined period of the operating speed of the actuator before the occurrence of the instantaneous interruption, and one of these two values having the larger value. The variable valve system is characterized in that the deviation amount is estimated by using a valve. The variable valve system according to claim 1, further comprising a determination unit that determines that the variable valve system is abnormal when the deviation amount estimated by the estimation unit is greater than or equal to a predetermined abnormality determination value. The variable valve system according to claim 2 , wherein the determination unit determines that the abnormality is present on the condition that an operation direction of the actuator before the momentary interruption is a direction in which a valve stamp is more easily generated. The variable valve system according to claim 2 or 3 , wherein the determination unit immediately determines that there is an abnormality when the instantaneous interruption time is equal to or greater than a predetermined value. Wherein when the shift amount estimated by the estimating means is less than predetermined abnormal determination value, according to claim 2-4 to continue the variable control of the guard range of the valve characteristic value expanded than usual same valve characteristic value The variable valve operating system according to any one of claims. The variable valve system according to claim 5 , wherein the expansion of the guard range is performed by offsetting the guard range by the estimated value of the deviation amount by the estimation unit. It said estimating means, variable valve system as claimed in any one of claims 1 to 6 using the engine rotational speed for the estimation of the amount of deviation.

Images