JP4182836B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a valve operating device for an internal combustion engine that drives an intake valve or an exhaust valve of the internal combustion engine. More specifically, the present invention relates to a cam drive mechanism that opens and closes the valve by the cooperation of a cam and a spring, and an auxiliary that assists the drive. The present invention relates to a valve operating apparatus for an internal combustion engine including a drive mechanism.

  As a valve operating device for an internal combustion engine, a valve drive device that includes a cam drive mechanism that opens and closes an intake valve and an exhaust valve by cooperation of a cam and a valve spring is generally used. In such a cam drive mechanism, when the engine rotational speed becomes high, there is a possibility that the valve (or the rocker arm that transmits the driving force of the cam to the valve) may be separated from the cam surface during the valve closing. . In this case, since the valve opens with an opening different from that corresponding to the cam profile, it is difficult to obtain a predetermined valve opening / closing characteristic. For this reason, normally, when setting the rigidity of the valve spring, specifically, the spring coefficient thereof, it is desirable to set it high enough to suppress the above-mentioned separation phenomenon in the high rotation range of the internal combustion engine. On the other hand, when the rigidity of the valve spring is increased in this way, in other words, when the lift load is increased, an unnecessary rotational resistance acts on the camshaft in the low rotation range of the internal combustion engine. This increases the driving loss of the internal combustion engine, which is not preferable.

Therefore, conventionally, as described in Patent Document 1, for example, an auxiliary drive mechanism (electromagnetic actuator) is provided separately from the cam drive mechanism, and an urging force corresponding to the engine rotational speed is applied to the valve through the mechanism. Yes. In other words, the auxiliary drive mechanism is operated when the valve is in the vicinity of its fully open position, and the biasing force in the closing direction is applied to the valve at a high rotation and in the opening direction at a low rotation. By changing the rotation speed according to the rotation speed, an increase in driving loss is suppressed and the separation phenomenon is also suppressed.
JP-A-2-221608

  Incidentally, in recent years, there has been an increasing demand for increasing the maximum allowable rotational speed of the engine from the viewpoint of improving the engine output. Then, when the intake valve or the exhaust valve closes in response to the request, that is, the speed at which the valve is seated on the valve seat (sitting speed) tends to become extremely high. As a result, the impact at the time of seating becomes large, and a phenomenon that the valve once seated rebounds away from the valve seat, that is, so-called bounce is likely to occur. By design, the maximum allowable rotational speed is set to the highest possible speed within a range where no bounce occurs. However, for example, when the contact portion between the valve and the valve seat has changed to a shape that tends to rebound due to long-term use, or the combustion state of the combustion chamber at the time of valve opening has changed to something that was originally designed In some cases, bounces may occur.

  When such a bounce occurs, the intake valve and the exhaust valve are opened during an inappropriate period. As a result, the intake charging efficiency and the exhaust efficiency are lowered, and as a result, the engine characteristics (engine output, exhaust properties, etc.) ) May cause inconvenience such as deterioration. Further, since the frequency of collision between the valve and the valve seat increases, the occurrence of hitting sound due to the collision and the decrease in durability of these members cannot be ignored. Note that the apparatus described in the above document basically does not pay attention to the occurrence of such bounce, and of course, it cannot cope with this appropriately.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a valve operating apparatus for an internal combustion engine that can suitably suppress the occurrence of bounce.

In the following, means for achieving the above object and its effects are described.
A first aspect of the present invention is a cam drive mechanism for opening and closing a valve that is attached to and detached from a valve seat of an intake port or an exhaust port of an internal combustion engine by cooperation of a cam and a spring, and a direction in which the valve is opened and closed. In the valve operating apparatus for an internal combustion engine having an auxiliary drive mechanism that generates a biasing force that selectively biases in any of the directions and assists the driving thereof, a detecting means that detects the displacement of the valve, and the cam In the seating period in which it is estimated that the valve is seated on the valve seat on the assumption that the valve is opened and closed based on the drive of the drive mechanism, the position of the valve based on the detection result of the detection means is the valve to be in a position away from the valve seat as a condition to its gist in that it comprises a control means for controlling the urging force of the auxiliary drive mechanism to be biased in the closing direction.

In this structure, the biasing force of the closing direction through the auxiliary drive mechanism on condition that the position of the valve based on the detection result is in the position spaced from the valve seat of Oite the detecting means to the seating period valve Therefore, the occurrence of bounce is suppressed by this biasing force.
The magnitude of the urging force can be set, for example, to be constant during the seating period, or can be set to be larger as the initial period of the seating period during which bounce is likely to occur. However, in order to apply the urging force to the valve through the auxiliary drive mechanism in this way, naturally, energy consumption in the mechanism is unavoidable.

In this regard, in the same configuration, it provided that e Bei detection means for detecting a displacement of the valve, the control means in a position where the position of the valve based on the detection result of the detecting means be in the seating period is separated from the valve seat biasing force to control the auxiliary drive mechanism to generate as, such order to adopt a configuration so that such energy consumption can be minimized.

Also, the amount of rebound when the valve rebounds from the valve seat, that is, the separation distance between the valve and the valve seat, and the speed of the valve when the valve rebounds away from the valve seat, that is, the target speed (= 0) The occurrence status of bounce can be evaluated by the deviation from the actual speed. It can be said that the larger the distance and the speed, the larger the bounce occurs. In this regard, in the configuration according to claim 2 , since the magnitude of the urging force is changed according to such a separation interval and speed, the occurrence of bounce can be more suitably suppressed.

  Here, focusing only on bounce suppression, for example, the urging force can be set only in accordance with the valve speed (exactly, the deviation between the target speed and the actual speed). According to this configuration, since the urging force acts on the valve as a damping force that suppresses the vibration phenomenon generated in the valve, the occurrence of bounce can be suitably suppressed. However, in this case, the convergence when the valve converges to the target position, that is, the seating position, is lowered. Therefore, it is desirable that the urging force increases the component (rigid force) that changes according to the separation interval while increasing the component (damping force) according to the speed of the valve.

According to a third aspect of the present invention, there is provided a cam drive mechanism that opens and closes a valve that is attached to and detached from a valve seat of an intake port or an exhaust port of an internal combustion engine by the cooperation of a cam and a spring; In the valve operating apparatus for an internal combustion engine, which has an auxiliary drive mechanism that generates a biasing force that selectively biases in any of the directions and assists the drive, a detection unit that detects an actual driving mode of the valve; Control means for controlling the auxiliary drive mechanism so that a biasing force having a magnitude corresponding to the degree of deviation between the target drive mode of the valve based on the drive of the cam drive mechanism and the detected actual drive mode is generated. The gist is to provide it.

  According to this configuration, since the biasing force set according to the degree of deviation between the target drive mode and the actual drive mode is applied to the valve, the target drive mode is to drive the valve according to the cam profile. In this case, when the actual drive mode of the valve is different from such a target drive mode, it is possible to quickly correct this with an urging force corresponding to the degree of deviation.

  Further, such a biasing force can always be generated, for example, when there is a difference between the actual drive mode and the target drive mode. However, in order to apply the urging force to the valve through the auxiliary drive mechanism in this way, naturally, energy consumption in the mechanism is unavoidable.

Therefore, as described in the fourth aspect of the invention, if the urging force is generated on the condition that the valve is seated by the cam drive mechanism so that the valve can be seated on the valve seat, this energy consumption can be reduced. Can be kept as small as possible.

On the other hand, the auxiliary drive mechanism is controlled so that the biasing force is generated on the condition that the valve is biased in the closing direction through the cam drive mechanism, as in the invention of claim 5. If the configuration is adopted, for example, the speed at which the valve is seated on the valve seat can be controlled prior to the seating period, so that it is possible to more suitably suppress the occurrence of bounce. It becomes like this.

Further, as described in claim 6 , the driving mode of such a valve can include the displacement of the valve and the speed of the valve. For example, when the displacement of the valve is the above drive mode, the displacement when the valve is driven through the cam drive mechanism is the target displacement, and the urging force is set based on the deviation between the target displacement and the actual displacement. To. Further, when the valve speed is the above drive mode, the speed when the valve is driven through the cam drive mechanism is set as the target speed, and the biasing force is set based on the deviation between the target speed and the actual speed. To.

Further, the urging force U can be set based on the relational expression: U = K1 · ΔX + C1 · ΔV, as in the seventh aspect of the invention. Here, the biasing force that biases the valve in the opening direction when the biasing force U> 0 is meant. “ΔX” is a deviation between the target displacement and the actual displacement of the valve (= target displacement−actual displacement: positive in the opening direction), and “ΔV” is a deviation between the target velocity of the valve and the actual velocity (= target velocity). -Actual speed). Furthermore, “K1” and “C1” are coefficients.

In this relational expression, the coefficient K1 is preferably set so that the relational expression: √ ((K + K1) / M)> ωc is satisfied, as in the eighth aspect of the invention. As a result, the natural frequency ωv (= √ ((K + K1) / M)) of the spring-mass system constituted by the valve, the spring, and the auxiliary drive mechanism is set to be higher than the angular frequency ωc of the camshaft. Occurrence of a phenomenon that does not follow the movement of the cam can be suppressed, and as a result, the occurrence of bounce caused by the phenomenon can be suppressed more suitably.

Further, in the above relational expression, as for the coefficient C1, as in the invention according to claim 9 , each relational expression: ζ ≧ 1, 2 · ζ · ωv = (C + C1) / M, ωv = √ ((K + K1) / M ) Should be set so that each is satisfied. Thereby, about the spring-mass system comprised by a valve, a spring, and an auxiliary drive mechanism, the vibration property can be made low and generation | occurrence | production of a bounce can be suppressed more suitably.

  Normally, in a valve operating device, a gap called a valve clearance is provided in order to prevent the valve from opening due to thermal expansion of the valve. Therefore, when the valve opens, when such a gap disappears, members such as a cam and a valve collide with each other to generate a collision sound. In particular, such a collision sound tends to increase at a high rotation speed when the rotation speed of the cam increases.

In this regard, according to the invention described in claim 10 , the control means generates a biasing force that biases the valve in the opening direction until a predetermined period elapses from the time when the valve starts to be biased in the opening direction by the cam drive mechanism. By adopting a configuration such as controlling the auxiliary drive mechanism, the collision force between the members when the valve is opened can be weakened, and the occurrence of the collision noise caused by the member can be suppressed. Become. Note that the magnitude of the urging force at this time is, for example, set constant in the predetermined period, set larger as the initial period of the predetermined period, or set larger as the engine rotates at a higher speed, etc. It is effective in suitably reducing.

The invention according to claim 11 is the valve operating apparatus for an internal combustion engine according to any one of claims 1 to 10 , wherein the auxiliary drive mechanism can apply a biasing force to the valve without contacting the valve. Its gist is that it is a non-contact type drive mechanism.

  According to this configuration, when the auxiliary drive mechanism is not in operation, it is possible to avoid as much as possible the force that impedes the movement of the valve, such as a friction damping force generated when the auxiliary drive mechanism is driven, and to reduce the drive loss. The increase can be suppressed.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a valve operating apparatus for an internal combustion engine according to the present invention is embodied will be described.
In the valve operating apparatus according to the present embodiment, the intake valve or the exhaust valve of the internal combustion engine is driven to reciprocate by the cooperation of the cam and the valve spring formed on the camshaft, and the communication between the intake or exhaust port and the combustion chamber is cut off. Is for switching. The valve operating characteristics of these valves are basically determined by the cam shape corresponding to each valve, that is, the cam profile. In addition, since the intake valve and the exhaust valve have substantially the same configuration, they will be described below without particularly distinguishing them.

FIG. 1 shows a valve gear according to the present embodiment. This device is a direct-acting valve operating device in which a valve is directly driven by a cam.
As shown in FIG. 1, the valve 12 has a shaft 12a and a valve body 12b, and the shaft 12a is supported by the cylinder head 10 so as to be able to reciprocate. A lifter 14 is mounted on the upper end of the valve 12, and the lifter 14 is normally urged by a valve spring 16 in the closing direction (upward in FIG. 1).

  A camshaft 20 is rotatably supported on the cylinder head 10. A cam 18 that can contact the lifter 14 is formed at a position corresponding to each valve 12 in the camshaft 20. The camshaft 20 is drivingly connected to a crankshaft of the internal combustion engine through a timing belt (not shown). When the internal combustion engine is operated and the camshaft 20 rotates, the pressing force by the cam 18 acts on the lifter 14 at a predetermined timing, and the lifter 14 is pushed down against the biasing force of the valve spring 16 by this pressing force. . As a result, the valve 12 is separated from the valve seat 10a and is opened. As a result, the port 22 communicates with the combustion chamber 23 of the internal combustion engine. In the present embodiment, a cam drive mechanism is configured by the valve spring 16, the cam 18, the cam shaft 20, and the like. Note that the spring coefficient K of the valve spring 16 is set to a small value to cope with a low engine speed NE in order to reduce drive loss.

  On the other hand, the valve gear of the present embodiment includes an actuator 24 that urges the valve 12 in the opening direction or the closing direction separately from the cam 18 and the valve spring 16. The actuator 24 is a non-contact type moving coil actuator. By using such a non-contact type actuator 24, a force that impedes the movement of the valve 12, such as a friction damping force generated when the actuator 24 is driven when the actuator 24 is not operated, is avoided as much as possible. The suppression of the increase is achieved. In the present embodiment, the actuator 24 functions as an auxiliary drive mechanism that assists in driving the cam drive mechanism.

  Specifically, the actuator 24 includes an electromagnetic coil 26 that is displaced integrally with the valve 12, and a permanent magnet 28 that is formed in a cylindrical shape so as to surround the electromagnetic coil 26. The electromagnetic coil 26 is attached to the shaft 12a of the valve 12, and the permanent magnet 28 is attached to the cylinder head 10. As shown in FIG. 1, the electromagnetic coil 26 is disposed in the permanent magnet 28 when the valve 12 is in its seating position. For this reason, the amount of magnetic flux leakage of the electromagnetic coil 26 is minimized when the valve 12 is in the seating position.

  The electromagnetic coil 26 is selectively driven by the drive circuit 33 to selectively generate electromagnetic forces having different magnetic field directions. As a result, a repulsive force or an attractive force is generated between the electromagnetic coil 26 and the permanent magnet 28 according to the direction of the magnetic field of the electromagnetic force. When a suction force is generated between them, the valve 12 is biased in the closing direction, and when a repulsive force is generated, the valve 12 is biased in the opening direction.

  Further, the internal combustion engine according to the present embodiment is provided with various sensors for detecting the operating state. Specifically, for example, a crank sensor for detecting the rotational speed (engine rotational speed NE) and rotational phase (crank phase) of the crankshaft, and a cam sensor for detecting the rotational phase (cam phase) of the camshaft 20. Is provided. A displacement sensor 30 for detecting the actual displacement X of the valve 12 is also provided. As the displacement sensor 30, a non-contact type sensor such as an eddy current type sensor is used in order to suppress an increase in the weight of the valve 12 as much as possible.

  The actual displacement X is detected based on the seating position of the valve 12 as a reference (actual displacement X = “0”) in the opening direction from the seating position. In the present embodiment, the displacement sensor 30 functions as detection means for detecting the actual drive mode of the valve, specifically, its displacement (position).

  Furthermore, the internal combustion engine according to the present embodiment includes an electronic control device 32 having, for example, a microprocessor (not shown), a memory 32a, and the like. The electronic control device 32 takes in the detection signals of the various sensors and performs various calculations, and controls the operating state of the internal combustion engine based on the calculation results. The electronic control device 32 executes control related to the auxiliary drive mechanism, specifically, the actuator 24 and the like as one of such various controls.

Hereinafter, a control mode of the valve gear configured as described above will be described.
In the valve gear according to the present embodiment, when a displacement deviation ΔX (= Xt−X) occurs between the actual displacement X and the target displacement Xt of the valve 12, the rigidity force of the valve gear according to the displacement deviation ΔX. Actuator 24 is actuated so that is apparently increased. Further, in addition to such a displacement deviation ΔX, when a speed deviation ΔV (= Vt−V) occurs between the actual displacement speed (hereinafter, actual speed) V of the valve 12 and the target speed Vt, the speed deviation ΔV is set. In response, the actuator 24 is actuated so that the damping force of the valve operating device is apparently increased. Through the drive control of the actuator 24, a phenomenon that the valve 12 is separated from the cam surface during bounce or valve closing, that is, a so-called jump is suppressed.

  FIG. 2 is a flowchart showing a specific processing procedure of the drive control of the actuator 24. In the present embodiment, this drive control process functions as a control means for controlling the urging force of the auxiliary drive mechanism.

Hereinafter, the processing procedure will be described in detail with reference to FIG.
The series of processes shown in this flowchart is executed by the electronic control device 32 as a process for each predetermined cycle.

In the present embodiment, the auxiliary drive mechanism is controlled so that an urging force U having a magnitude corresponding to the degree of deviation between the target drive mode and the actual drive mode is generated through this series of processes. Here, the urging force U is obtained based on the following equation (1). Here, the biasing force that biases the valve 12 in the opening direction when the biasing force U> 0 is meant.

U = K1 · ΔX + C1 · ΔV (1)
ΔX: displacement deviation ΔX between the target displacement Xt of the valve 12 and the actual displacement X
ΔV: Speed deviation ΔV between the target speed Vt of the valve 12 and the actual speed V
K1, C1: coefficient

In the above equation (1), the first term K1 · ΔX on the right side is a term proportional to the displacement deviation ΔX, and apparently increases or decreases the rigidity force of the spring-mass system composed of the cam drive mechanism and the auxiliary drive mechanism. can do. In the same formula (2), the second term C1 · ΔV on the right side is a term proportional to the velocity deviation ΔV, and the damping force of the spring-mass system can be apparently increased or decreased in the same term.

Hereinafter, the control procedure of the auxiliary drive mechanism including the method for calculating the urging force U will be sequentially described.
In this process, first, it is determined whether or not the cam phase θ is within the predetermined phase range S (step S100).

  Here, the predetermined phase range S starts from the first phase (θ1) where the jump or bounce starts to occur, and extends from the first phase θ1 to the second phase (θ2) where the possibility is almost eliminated. It is set as a phase range (A: θ1 <θ <θ2).

  As shown in FIG. 3, specifically, the first phase θ1 is based on the assumption that the valve 12 is opened and closed according to the cam profile. The cam phase corresponding to is set. Further, the second phase θ2 reaches the phase θc corresponding to the position where the valve 12 is seated on the valve seat 10a on the assumption that the valve 12 is opened and closed according to the cam profile, and then further reaches the predetermined phase θa. It is set to the cam phase when it has advanced only.

When the cam phase θ is not within the predetermined phase range S (step S100: NO), the processing after step S102 is not executed, and this processing is temporarily ended.
On the other hand, when the cam phase θ is within the predetermined phase range S (step S100: YES), each parameter M, C, K in the following equation (2) is read from the memory 32a (step S102).

F = M · A + C · V + K · X (2)
A: Valve acceleration (second-order differential value of X)
V: Valve speed (first derivative of X)

The above equation (2) indicates that the equivalent mass of the spring-mass system constituted by the cam drive mechanism and the auxiliary drive mechanism, that is, the valve 12, the valve spring 16, and the actuator 24, is M, the damping coefficient is C, and the spring coefficient is K. Is an equation of motion related to a vibration model. Specifically, the equivalent mass M is the mass of the movable part in the vibration model such as the lifter 14 including the valve 12 and the electromagnetic coil 26. Incidentally, in the pivot type valve gear device of the pivot type or the rocker arm type, the mass of the rocker arm is included in the equivalent mass M. The damping coefficient C is set based on the resistance force generated according to the valve speed in each part of the valve operating device, specifically, the cam drive mechanism and the auxiliary drive mechanism. Further, the spring coefficient K is mainly set to be substantially equal to the elastic characteristic of the valve spring 16, that is, the spring coefficient K of the valve spring 16.

  Thereafter, the target displacement Xt corresponding to the current cam phase θ is read from the memory 32a, and a displacement deviation ΔX (= Xt−X) between the target displacement Xt and the actual displacement X of the valve 12 is calculated (step S104). ). Here, the displacement of the valve 12 when the valve 12 is displaced along the cam profile is set as the target displacement Xt. In the control according to the present embodiment, the displacement of the valve 12 is one of the driving modes, and the displacement deviation ΔX between the target displacement Xt and the actual displacement X is a parameter indicating the degree of deviation between the target driving mode and the actual driving mode. It is used as.

  On the other hand, after the displacement deviation ΔX is calculated, the target speed Vt of the valve 12 is calculated based on the temporal transition of the target displacement Xt, and the actual speed V is calculated based on the temporal transition of the actual displacement X. . Then, a speed deviation ΔV (= Vt−V) between the target speed Vt and the actual speed V is calculated (step S106). In the control according to the present embodiment, the speed of the valve 12 is one of the driving modes, and the speed deviation ΔV between the target speed Vt and the actual speed V is a parameter indicating the degree of deviation between the target driving mode and the actual driving mode. It is used as.

After the displacement deviation ΔX and the speed deviation ΔV are calculated in this way, the angular frequency ωc of the camshaft 20 is calculated based on the engine rotational speed NE, and the previous relationship is calculated based on the following relational expression (3). A coefficient K1 of equation (1) is obtained (step S108).

√ ((K + K1) / M) = ωc · α (3)
α: Constant

The left side √ ((K + K1) / M) in the equation (3) is the value of the spring-mass system constituted by the cam drive mechanism and the auxiliary drive mechanism in consideration of the urging force U of the auxiliary drive mechanism shown in the equation (1). It is a natural frequency. The constant α is a predetermined value sufficiently larger than “1.0”. In the present embodiment, the coefficient K1 is set through the above equation (3) so that the natural frequency ωv of the spring-mass system is higher than the angular frequency ωc of the cam 18.

Next, the coefficient C1 of the previous equation (1) is calculated based on the following relational equation (4) (step S110).

(C1 + C1) / M = 2 · ζ · ωv (4)
However, ωv = √ ((K + K1) / M)
ζ: magnification

Note that a value of “1.0” or more is used as the enlargement ratio ζ in the above equation (4). Thus, in the present embodiment, a value that reduces the vibration of the cam drive mechanism and the auxiliary drive mechanism is calculated as the coefficient C1.

  When the displacement deviation ΔX, the speed deviation ΔV, the coefficient K1, and the coefficient C1 are calculated in this way, the urging force U of the actuator 24 is calculated based on the previous equation (1) (step S112).

Then, the target current It of the actuator 24 is calculated based on the biasing force U calculated in this way (step S114). Specifically, after the target current It satisfying the following relational expression (5) is calculated based on the urging force U and the separation interval (= actual displacement X) between the valve 12 and the valve seat 10a, this processing is performed. Is temporarily terminated.

It = U / G (5)
G: Coefficient

The coefficient G is a constant determined by the characteristics of the actuator 24, and the target value of the biasing force U obtained from the equation (1) is equal to the actual value of the biasing force applied to the valve 12 by the actuator 24. Thus, it is calculated | required through experiment etc. and is memorize | stored in the memory 32a of the electronic controller 32.

  In the valve gear according to the present embodiment, a drive signal corresponding to the target current It is output to the drive circuit 33, and the drive circuit 33 is controlled so that the drive current of the actuator 24 matches the target current It. . As a result, the urging force of the actuator 24 is adjusted to the value of the urging force U obtained through the above equation (5).

  In the valve operating apparatus according to the present embodiment, in order to reduce drive loss, the spring coefficient K of the valve spring 16 is set to be low so as to correspond to when the engine speed NE is low. For this reason, for example, as shown in FIG. 3, the jump (θ1 to θd) and the bounce (θd to θ2) described above may occur. In this regard, in the apparatus according to the present embodiment, the actuator 24 generates an urging force (= C1 · ΔV) proportional to the speed deviation ΔV, whereby a spring-mass system constituted by the cam drive mechanism and the auxiliary drive mechanism. The damping force is increased. As a result, the spring-mass system has a characteristic that it is difficult to vibrate, whereby the occurrence of the bounce is suitably suppressed.

  Furthermore, in addition to such a damping force, an urging force (= K1 · ΔX) proportional to the displacement deviation ΔX of the actuator 24 is generated, and the rigidity force of the spring-mass system is also increased. Furthermore, when setting this urging force, the coefficient K1 is set so that the natural frequency ωv of the spring-mass system is sufficiently higher than the angular frequency ωc of the cam 18. Therefore, the valve 12 can follow the movement of the cam 18 to reciprocate, and the occurrence of the jump is also suppressed.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) An actuator that generates an urging force according to the degree of deviation between the target driving mode and the actual driving mode of the valve 12 based on the driving of the cam driving mechanism, that is, an urging force U according to the displacement deviation ΔX and the speed deviation ΔV. 24 was controlled. For this reason, when a bounce occurs during the seating period, a biasing force in the closing direction that suppresses the bounce is applied from the actuator 24 to the valve 12. As a result, the occurrence of bounce can be suppressed by this biasing force.

  (2) When bounce does not occur and the valve 12 is seated, that is, when the displacement deviation ΔX and the velocity deviation ΔV are both “0”, the relational expressions (1) and (5) As is apparent, the urging force U is “0”, and the target current It is also “0”. That is, in the apparatus according to the present embodiment, the actuator 24 is driven only when the position of the valve 12 is away from the valve seat 10a, so that energy consumption in the actuator 24 can be minimized. become.

  (3) Further, not only the seating period but also the control over the actuator 24 is performed over the entire period (θ1 to θc in FIG. 3) in which the valve 12 is biased in the closing direction by the cam drive mechanism. Therefore, the speed at which the valve 12 is seated on the valve seat 10a can be controlled prior to the seating period, and the occurrence of bounce can be more suitably suppressed.

  (4) By setting the coefficient K1 of the relational expression (1) so as to satisfy the relational expression (3), the natural vibration of the spring-mass system constituted by the valve 12, the valve spring 16, and the actuator 24 The number ωv is set higher than the angular frequency ωc of the camshaft 20. As a result, it is possible to suppress the occurrence of a phenomenon in which the valve 12 does not follow the movement of the cam 18, and thus it is possible to more suitably suppress the occurrence of bounce due to the phenomenon.

  (5) By setting the coefficient C1 of the relational expression (1) so as to satisfy the relational expression (4), the spring-mass system has a characteristic that is difficult to vibrate. Thereby, generation | occurrence | production of a bounce can be suppressed more suitably.

  (6) The actuator 24 is a non-contact type actuator that can apply a biasing force to the valve 12 without contacting the valve 12. For this reason, when the actuator 24 is not in operation, it is avoided as much as possible that a force that impedes the movement of the valve 12 such as a friction damping force generated when the actuator 24 is driven, and an increase in driving loss is suppressed. Will be able to.

In addition, you may implement the said embodiment, changing as follows.
The actuator 24 may be operated so that a biasing force that biases the valve 12 in the opening direction is generated until a predetermined period elapses from the time when the valve 12 starts to be biased in the opening direction. Normally, in the valve operating apparatus, a gap (a gap indicated by L in FIG. 1) called a valve clearance is provided in order to prevent the valve 12 from opening due to thermal expansion. Therefore, when the valve 12 is opened, when such a gap disappears, the lifter 14 and the cam 18 collide with each other to generate a collision sound. In this respect, according to the above-described configuration, the collision force between the lifter 14 and the cam 18 when the valve 12 is opened can be weakened, and the occurrence of the collision noise resulting therefrom can be suppressed. Note that it is effective in reducing the collision noise that the magnitude of the urging force at this time is, for example, set to be constant in the predetermined period or set to be larger at the beginning of the predetermined period.

  Further, such a collision sound tends to increase at a high rotation speed when the rotation speed of the cam 18 increases. For this reason, if the urging force is generated when the rotation speed of the cam 18 exceeds a predetermined speed, or if the urging force is set to be larger as the rotation speed is higher, the generation of a collision sound is made in accordance with the above tendency. It becomes possible to suppress suitably.

  In the above embodiment, the starting point of the predetermined phase range S may be set to the phase θe between the first phase θ1 and the phase θc at which the actual displacement X becomes the seating position. Even in such a configuration, as indicated by a two-dot chain line in FIG. 4, when the cam phase θ subsequently falls within the predetermined phase range, the damping force acting on the valve 12 is increased and the actual speed V is decreased. Become. Thereby, the actual speed V of the valve 12 at the time of seating of the valve 12 can be reduced, and the occurrence of bounce can be suitably suppressed.

The starting point of the predetermined phase range S may be set to the phase θc. According to this configuration, energy consumption by the actuator 24 can be minimized.
As shown in FIG. 5 as a modified example of the drive control process, it is determined whether or not the bounce has occurred and that the bounce has been determined (step S200: YES). To S114 (FIG. 2) may be executed. According to this configuration, when a bounce occurs, the actuator 24 can be operated in accordance with the bounce. The occurrence of bounce can be determined by the fact that the actual displacement X of the valve 12 is different from “0” during the seating period. Further, for example, it is desirable to stop the operation of the actuator 24 after waiting for a predetermined time that the actual displacement X of the valve 12 is “0” (steps S202 and S204). If comprised in this way, it will become possible to suppress the destabilization of the control by repeating the action | operation / non-operation of the actuator 24 within a short period of time.

  Further, when it is determined that the bounce has occurred, the actuator 24 may be operated so as to generate a biasing force that biases the valve 12 in the closing direction regardless of the displacement deviation ΔX or the speed deviation ΔV. Is possible.

  The state of occurrence of bounce during operation of the actuator 24 is monitored, and when the occurrence of bounce cannot be suppressed despite the actuator 24 being operated, the coefficients K1 and C1 are changed to larger values. May be. According to this configuration, it is possible to accurately suppress the occurrence of bounce according to the secular change of the valve gear and individual differences. On the other hand, when the bounce is not generated as a result of the actuator 24 being operated, the coefficients K1 and C1 can be gradually reduced. In this way, the power consumption of the actuator 24 can be suppressed as much as possible. Further, as shown in the previous example, even when the urging force is set regardless of the displacement deviation ΔX and the speed deviation ΔV, the urging force is similarly changed in a manner corresponding to the bounce occurrence state. be able to.

  In addition to the displacement deviation ΔX and the speed deviation ΔV, the driving of the actuator 24 may be controlled according to the acceleration deviation ΔA between the displacement acceleration A of the valve 12 and the target displacement acceleration At. According to this configuration, precise control can be performed, and the occurrence of bounce can be more accurately suppressed.

  Further, the driving of the actuator 24 is controlled based on any one of the displacement deviation ΔX, the speed deviation ΔV, and the acceleration deviation ΔA, or one of the displacement deviation ΔX and the speed deviation ΔV and the acceleration deviation ΔA. It may be.

  The starting point of the predetermined phase range S is the phase θc, and the actuator 24 generates a biasing force that biases the valve 12 with a constant force in the closing direction regardless of the displacement deviation ΔX and the speed deviation ΔV in the predetermined phase range. May be activated.

  Further, with respect to the predetermined phase range S, the first phase (θ1) where the jump or bounce starts to occur is set as the starting point, and the range from the same phase θ1 to the second phase (θ2) where the possibility is almost eliminated Although set, the second phase (θ2) can be further set to the retard side. In this way, for example, the valve 12 can be held in a closed state by suppressing the valve 12 from opening due to vibrations of the engine or the vehicle in addition to jumping and bouncing.

The start point of the predetermined phase range S may be set when the actual displacement X of the actual valve 12 detected by the displacement sensor 30 becomes “0”.
In addition, a large force may be generated as the urging force when the valve 12 is seated, and thereafter, the actuator 24 may be operated so that the force gradually decreases. When bounce occurs, the strength is greatest immediately after the valve 12 is seated, and then gradually decreases. According to the above configuration, the actuator 24 can be controlled in a manner corresponding to the transition of the bounce strength.

  As shown in FIG. 6, by arranging the actuator 24 so as to be accommodated in the lifter 14 and the valve spring 16, the apparatus can be downsized in the axial direction of the valve 12.

  The actuator 24 is not limited to a moving coil type actuator, and other linear actuators such as a linear motor and a linear stepping motor can be used. In addition to those using such electromagnetic force, fluid pressure type actuators such as oil and air can also be used. Furthermore, the method is not limited to using a non-contact type actuator, and the valve 12 may be directly driven via a gear or the like.

  The displacement sensor 30 in the above embodiment is not limited to an eddy current type position sensor, but other electromagnetic induction type position sensors such as a differential transformer, an optical position sensor, or an ultrasonic position A sensor or the like can also be used. Further, not only the non-contact type position sensor but also a contact type position sensor such as a potentiometer can be used.

  The present invention is not limited to the above-described type of valve operating device, but can be applied to other types of valve operating devices such as pivot type or rocker arm type valve operating devices. In any type of valve operating device, it is possible to appropriately suppress the occurrence of a bounce and the occurrence of a collision sound when the valve clearance disappears.

The block diagram which shows schematic structure of one embodiment of this invention. 6 is a flowchart showing a processing procedure of drive control processing according to the embodiment; FIG. 3 is a schematic diagram showing how a predetermined phase range is set according to the same embodiment. FIG. Schematic which shows an example of the displacement aspect of the valve in other embodiment. The flowchart which shows the process sequence of the drive control process concerning other embodiment. The block diagram which shows the valve gear concerning other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Cylinder head, 10a ... Valve seat, 12 ... Valve, 12a ... Shaft, 12b ... Valve body, 14 ... Lifter, 16 ... Spring, 18 ... Cam, 20 ... Cam shaft, 22 ... Port, 23 ... Combustion chamber, 24 DESCRIPTION OF SYMBOLS ... Actuator, 26 ... Electromagnetic coil, 28 ... Permanent magnet, 30 ... Displacement sensor, 32 ... Electronic control unit, 32a ... Memory, 33 ... Drive circuit.

Claims (11)

A cam drive mechanism that opens and closes a valve that is attached to and detached from a valve seat of an intake port or an exhaust port of an internal combustion engine by the cooperation of a cam and a spring, and the valve is selectively attached in one of the opening and closing directions. In a valve operating apparatus for an internal combustion engine having an auxiliary drive mechanism that generates an urging force to assist and assists the drive,
Detecting means for detecting displacement of the valve;
The position of the valve based on the detection result of the detecting means during a seating period in which the valve is assumed to be seated on the valve seat on the assumption that the valve is opened and closed based on the drive of the cam drive mechanism dynamic but of the internal combustion engine, characterized in that it comprises a control means for the valve on condition that a position away from the valve seat to control the urging force of the auxiliary drive mechanism to be biased in the closing direction Valve device. The internal combustion engine according to claim 1, wherein the control means controls the auxiliary drive mechanism so that the magnitude of the urging force changes according to at least one of a separation interval between the valve and the valve seat and a speed of the valve. Valve gear. A cam drive mechanism that opens and closes a valve that is attached to and detached from a valve seat of an intake port or an exhaust port of an internal combustion engine by the cooperation of a cam and a spring, and the valve is selectively attached in one of the opening and closing directions. In a valve operating apparatus for an internal combustion engine having an auxiliary drive mechanism that generates an urging force to assist and assists the drive,
Detecting means for detecting an actual driving mode of the valve;
Control means for controlling the auxiliary drive mechanism so as to generate a biasing force having a magnitude corresponding to the degree of deviation between the target drive mode of the valve based on the drive of the cam drive mechanism and the detected actual drive mode;
A valve operating apparatus for an internal combustion engine, comprising: The control means controls the auxiliary drive mechanism so that the urging force is generated on the condition that the valve is in a seating period during which the valve can be seated on the valve seat by the cam drive mechanism.
The valve operating apparatus for an internal combustion engine according to claim 3 . The internal combustion engine according to claim 3 or 4, wherein the control means controls the auxiliary drive mechanism so that the biasing force is generated on the condition that the valve is biased in the closing direction through the cam drive mechanism. Valve gear. The valve operating apparatus for an internal combustion engine according to any one of claims 3 to 5, wherein the driving mode includes at least one of a displacement of the valve and a speed of the valve. The control means sets the biasing force U to the following relational expression.

U = K1 · ΔX + C1 · ΔV (means an urging force for urging the valve in the opening direction when U> 0)
ΔX: Deviation between target displacement and actual displacement of valve (= target displacement-actual displacement: positive direction of opening)
ΔV: Deviation between the target speed of the valve and the actual speed (= target speed-actual speed)
K1, C1: coefficient

The valve gear for an internal combustion engine according to claim 2 or 6 , wherein the valve operating device is calculated on the basis of When the control means models an equivalent mass when the spring-mass system configured by the cam drive mechanism and the auxiliary drive mechanism is modeled as M, the damping coefficient is C, and the spring coefficient is K, the coefficient K1 is as follows. Relational expression

√ ((K + K1) / M)> ωc
ωc: Camshaft angular frequency

The valve gear for an internal combustion engine according to claim 7 , wherein the valve is set so that The control means sets the coefficient C1 to the following relational expressions:

ζ ≧ 1
2 · ζ · ωv = (C + C1) / M
ωv = √ ((K + K1) / M)

9. The valve operating apparatus for an internal combustion engine according to claim 8, wherein the valve is set so as to satisfy the above . The control means controls the auxiliary drive mechanism so that a biasing force that biases the valve in the opening direction is generated until a predetermined period elapses from a time when the valve starts to be biased in the opening direction by the cam driving mechanism. The valve gear for an internal combustion engine according to any one of claims 1 to 9 . Said auxiliary drive mechanism valve operating system for an internal combustion engine according to any of claims 1-10 which is a non-contact drive mechanism capable imparting a biasing force to the valve without contacting the valve.

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