JP2005180408A - Variable valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always give an optimal valve opening characteristic to a valve element in starting an internal combustion engine without influence of temperature change after stop of the engine, in a variable valve system for changing a state of a control shaft to change a lift amount of a valve element which is driven by a cam. <P>SOLUTION: An oscillating arm 44 is interposed between the cam 74 and the valve element 32. A variable mechanisms 46, 48 changes a reference relative angle of the oscillating arm 22 to the valve element 32 depending on a state of the control shaft 12. A temperature near the control shaft 12 in the stop of the engine is acquired as a stop time temperature, and an actual action angle in the stop of the engine is detected as a stop time action angle. A correction value for an operation angle suitable for a restart estimation temperature is calculated based on difference between the start estimation temperature (-35°C) and the stop time temperature of the engine, and the stop time action angle. Before the restart of the engine, a rotation position is corrected base on the correction value to change the action angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve mechanism, and more particularly to a variable valve mechanism for an internal combustion engine that can change the operating angle and / or lift amount of a valve that opens and closes in synchronization with the rotation of a camshaft.

  Conventionally, for example, Japanese Patent Application Laid-Open No. 7-63023 discloses a variable valve mechanism that changes a lift amount of a valve body in an internal combustion engine having a valve body that opens and closes in synchronization with the rotation of a camshaft. This variable valve mechanism includes a swing arm that swings in synchronization with the operation of the cam between the cam and the valve element. The swing arm is assembled to the internal combustion engine with a degree of freedom so that the basic relative angle with respect to the valve body can be changed. And this mechanism is a relative motion angle between the swing arm and the valve body in accordance with the rotation of the lost motion spring that regulates the motion of the swing arm by urging the swing arm toward the cam. And a variable mechanism for changing.

  According to the variable valve mechanism described above, the state where the cam and the swing arm are in mechanical contact with each other can always be maintained by the action of the lost motion spring. For this reason, according to this mechanism, the mechanical force generated by the cam can always be transmitted to the valve body without loss. Furthermore, according to this variable valve mechanism, the reference relative angle between the swing arm and the valve body can be changed by rotating the control shaft. When this relative angle changes, after the cam pressing force starts to be transmitted to the swing arm, that is, after the swing arm starts to swing due to the action of the cam, the swing arm actually starts to push down the valve body. The period until (crank angle) can be changed.

  When the period until the swing arm actually starts to push down the valve body changes, the width of the crank angle at which the valve body is in the non-closed state (hereinafter, the width is referred to as “working angle”) changes. The lift amount profile generated in the valve body changes. For this reason, according to the conventional mechanism, it is possible to change the operating angle and the lift amount of the valve body with a high degree of freedom.

Japanese Patent Laid-Open No. 7-63023 JP 7-293216 A

  The operating angle and lift amount for appropriately operating the internal combustion engine must be set appropriately according to the operating state. Specifically, when starting the internal combustion engine, it is necessary to set a working angle and a lift amount suitable for starting. However, when the internal combustion engine is stopped, a working angle and a lift suitable for starting the engine may not be realized. For this reason, in an internal combustion engine having a variable valve mechanism, it is necessary to correct the operating angle and the lift amount before the next start after the stop of the internal combustion engine is requested.

  In the conventional variable valve mechanism described above, the operating angle and lift amount of the valve body can be corrected by rotating the control shaft. For this reason, for example, when the internal combustion engine is requested to start, first, the rotational position of the control shaft is adjusted so that the operating angle and the lift amount suitable for the start are realized, and then the internal combustion engine is started. As a result, good starting characteristics can be obtained.

  However, in order to adjust the rotational position of the control shaft, it is necessary to detect the rotational position. Then, the relationship between the output of the sensor that enables the detection and the actual rotational position may change according to individual differences of the sensor and the variable valve mechanism, or changes with time thereof. Therefore, in order to correctly adjust the rotational position of the control shaft at the start of the internal combustion engine, it is necessary to perform the adjustment based on the sensor output in which the correlation with the state of the control shaft is correctly corrected. .

  The relationship between the rotational position of the control shaft and the sensor output for detecting the position can be calibrated by, for example, rotating the control shaft to the moving end and reading the sensor output obtained at that time. However, when the internal combustion engine is started, the sensor output cannot be calibrated by such a method due to time constraints. For this reason, as a method of satisfying the above requirements, the sensor output is calibrated after the internal combustion engine is started, and when the stop of the internal combustion engine is requested, the sensor output at the time of the request is changed to that of the control shaft at that time. It is considered appropriate to detect the rotation position (or the valve operating angle and the lift amount) and adjust the control axis for starting based on the sensor output.

  However, it is normal that the ambient temperature of the variable valve mechanism changes greatly after the internal combustion engine is stopped. For this reason, large thermal deformation tends to occur around the control shaft and the camshaft after the internal combustion engine is stopped. In the variable valve mechanism, when such thermal deformation occurs, the state of the swing arm interposed between the control shaft and the cam and the state of the variable mechanism for changing the angle of the swing arm change. .

  Specifically, in the conventional variable valve mechanism described above, when the temperature around the control shaft decreases, the distance between the control shaft and the camshaft is shortened, and as a result, the state of the swing arm becomes a large working angle.・ Phenomenon that changes in the direction of large lift occurs. On the other hand, when the temperature around the control shaft rises, the distance between the control shaft and the camshaft increases, and as a result, a phenomenon occurs in which the state of the swing arm changes in a small working angle and small lift direction. For this reason, in an internal combustion engine having a variable valve mechanism, a sensor output is acquired when the engine is stopped, and even if control axis adjustment for starting is performed based on the sensor output, the state of the control axis at the time of starting is The optimum operating angle and lift amount are deviated from each other by the amount of temperature change that occurs after the stop.

  The present invention has been made to solve the above-described problems. The valve body always has an optimum valve opening characteristic when starting the internal combustion engine without being affected by a temperature change that occurs after the internal combustion engine is stopped. An object is to provide a variable valve mechanism that can be provided.

In order to achieve the above object, a first invention is a variable valve mechanism having a function of changing a working angle and / or a lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
Non-corrected restart characteristic value calculating means for calculating a non-corrected restart characteristic value based on the difference between the assumed restart temperature of the internal combustion engine and the stop temperature, and the stop characteristic value;
Correction value calculating means for calculating a correction value for converting the non-corrected restart characteristic value into a working angle and / or lift amount suitable for the assumed restart temperature;
A pre-start correction means for correcting the state of the control shaft so that a change in the correction value occurs in the operating angle and / or the lift amount prior to restarting the internal combustion engine;
It is characterized by providing.

  In a second aspect based on the first aspect, the pre-start correction means performs the above correction when the internal combustion engine is stopped.

  According to a third aspect, in the first or second aspect, the assumed restart temperature is the lowest temperature in the operating temperature range of the internal combustion engine.

The fourth invention is a variable valve mechanism having a function of changing the operating angle and / or lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
A temperature-in-stop acquisition means for acquiring the temperature in the vicinity of the internal combustion engine as the temperature during stop;
Based on the stop temperature, the stop characteristic value, and the stop temperature, the operating angle and / or lift amount during stop of the internal combustion engine are maintained at values suitable for restart. A stopping correction means for correcting the state;
It is characterized by providing.

The fifth invention is the fourth invention, wherein
The stopping correction means includes:
First characteristic value fluctuation amount calculating means for calculating a first characteristic value fluctuation amount based on a difference between the temperature at the time of stop and the temperature during the stop;
First actual characteristic value calculation means for calculating a sum of the characteristic value at the time of stop and the first characteristic value fluctuation amount as an actual characteristic value;
Appropriate judgment means for judging whether or not the calculated actual characteristic value is a value suitable for restart;
Control axis correction means for correcting the state of the control axis so that the actual characteristic value becomes a value suitable for restarting when it is determined that the actual characteristic value is not suitable for restarting;
A corrected characteristic value calculating means for calculating a corrected characteristic value realized by correcting the control axis;
Second characteristic value fluctuation amount calculating means for calculating a second characteristic value fluctuation amount based on a temperature difference generated in the temperature during stop after the correction of the control axis;
Second actual characteristic value calculating means for calculating a sum of the corrected characteristic value and the second characteristic value fluctuation amount as an actual characteristic value;
It is characterized by including.

The sixth invention is a variable valve mechanism having a function of changing the operating angle and / or lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
Restart request temperature acquisition means for acquiring the temperature near the restart time of the internal combustion engine as a restart request temperature;
A non-correction restart request time characteristic value calculating means for calculating a non-correction restart request time characteristic value based on the difference between the restart request temperature and the stop temperature, and the stop characteristic value;
Correction value calculating means for calculating a correction value for converting the non-correction restart request time characteristic value into a characteristic value suitable for restart;
Pre-restart correction means for correcting the state of the control shaft so that the correction value changes in the operating angle and / or lift amount prior to restarting the internal combustion engine;
It is characterized by providing.

  According to a seventh invention, in any one of the fourth to sixth inventions, the internal combustion engine has a function of automatically stopping and starting without depending on a driver's operation. .

  According to the first invention, by rotating the control shaft, the state of the variable mechanism and the swing arm interposed between the control shaft and the cam is changed, and as a result, the valve opening characteristic of the valve body is changed. be able to. According to the present invention, the difference between the temperature when the internal combustion engine is stopped (temperature when the engine is stopped) and the assumed restart temperature of the internal combustion engine, the operating angle and / or the lift amount when the internal combustion engine is stopped (characteristic value at the time of stop) ) To calculate the operating angle and / or lift amount (characteristic value at the time of non-correction restart) that occurs when the control shaft state is restarted without being corrected. A correction value for converting the characteristic value into a characteristic value suitable for the assumed restart temperature can be calculated. Thereafter, correction based on the correction value is executed prior to restarting the internal combustion engine, so that the valve opening characteristic that is optimal under the assumed temperature can be given to the valve body whenever the internal combustion engine is restarted.

  According to the second aspect of the invention, the correction for realizing the valve opening characteristic that is optimal under the assumed temperature can be performed when the internal combustion engine is stopped. For this reason, according to this invention, after the request | requirement of a restart arises, an internal combustion engine can be restarted rapidly.

  According to the third aspect of the invention, when the internal combustion engine is started, an optimal valve opening characteristic under the lowest temperature in the operating temperature range can be given to the valve body. For this reason, according to the present invention, the internal combustion engine can be favorably started within the entire operating temperature range.

  According to the fourth invention, by rotating the control shaft, the state of the variable mechanism and the swinging arm interposed between the control shaft and the cam is changed, and as a result, the valve opening characteristic of the valve body is changed. be able to. According to the present invention, when the internal combustion engine is stopped (temperature when stopped), the temperature when the internal combustion engine is stopped (temperature during stop), the operating angle and / or the lift amount when the internal combustion engine is stopped (when stopped) By controlling the state of the control shaft based on the characteristic value), the operating angle and / or the lift amount during the stop of the internal combustion engine can always be maintained at values suitable for restart. For this reason, according to the present invention, it is possible to always give the valve element the optimum valve opening characteristic when the internal combustion engine is restarted.

  According to the fifth invention, based on the difference between the stop-time temperature and the stop-time temperature, the operating angle and / or lift amount fluctuation amount (first characteristic value fluctuation amount) from the stop-time characteristic value is calculated, The actual operating angle and / or the actual lift amount can be calculated by adding the fluctuation amount to the stop time characteristic value. If the actual operating angle and / or the actual lift amount are not values suitable for restart, the state of the control shaft can be corrected so that they become values suitable for restart. Thereafter, the operating angle or lift amount (corrected characteristic value) realized by the above correction is added to the operating angle and / or lift amount fluctuation amount (second characteristic value fluctuation amount) due to the temperature change after the correction. The actual working angle and / or the actual lift amount are calculated again. Each time they deviate from a value suitable for starting, the control shaft is corrected. As a result, the actual operating angle and / or the actual lift amount are always maintained at values suitable for restarting.

  According to the sixth invention, by rotating the control shaft, the state of the variable mechanism and the swing arm interposed between the control shaft and the cam is changed, and as a result, the valve opening characteristic of the valve body is changed. be able to. According to the present invention, when the restart of the internal combustion engine is requested, the difference between the temperature at the time of stop of the internal combustion engine (temperature at the time of stop) and the temperature at that time (temperature at the time of restart request), Based on the operating angle and / or lift amount (characteristic value at the time of stopping) of the internal combustion engine, the operating angle and / or lift amount that is generated when the engine is restarted in the stopped state (when an uncorrected restart request is made) Characteristic value), and a correction value for converting the non-correction restart request time characteristic value into a value suitable for restart can be calculated. Thereafter, correction based on the correction value is executed prior to restarting the internal combustion engine, so that at the time of restarting, a valve opening characteristic that is optimal for restarting is always imparted to the valve body.

  According to the seventh aspect of the invention, in the internal combustion engine having a function of automatically stopping and automatically starting, it is possible to always give the valve element the optimum valve opening characteristic at the time of restart. In an internal combustion engine having such a function, start and stop are repeated many times. Therefore, when the startability is improved by the present invention, the state of the internal combustion engine can be remarkably improved.

Embodiment 1 FIG.
[Overall configuration of variable valve mechanism]
FIG. 1 is a diagram for explaining an overall configuration of a variable valve mechanism according to Embodiment 1 of the present invention. More specifically, FIG. 1 (A) is a plan view showing the entire variable valve mechanism, and FIG. 1 (B) is a side view showing the mechanism as shown by arrow B in FIG. 1 (A). FIG.

  The configuration shown in FIG. 1 includes a cylinder head 10 of an internal combustion engine. The cylinder head 10 has a plurality of control shaft bearings 11 arranged so as to be positioned on both sides of each cylinder, and these control shaft bearings 11 hold the control shaft 12 rotatably. The internal combustion engine in the present embodiment includes four cylinders in series, and the control shaft 12 is provided so as to run vertically above the four cylinders.

  Each cylinder in the internal combustion engine includes an intake valve and an exhaust valve that open and close in synchronization with the rotation of the cam (both are not shown in FIG. 1). The variable valve mechanism in the present embodiment is a mechanism for making the operating angle and the lift amount variable at least for the intake valve of each cylinder. And the control shaft 12 mentioned above is a component by which a rotational position is controlled in order to enable the change of the working angle and lift amount.

  If the operating angle and lift amount of the intake valve can be freely changed, the intake air amount can be controlled without using the throttle valve by controlling them. If the intake air amount is controlled in such a manner, the intake pipe pressure can be prevented from becoming negative, and the pumping loss in the internal combustion engine can be eliminated. In order to obtain such an effect, the internal combustion engine in the present embodiment is a so-called throttle-less internal combustion engine in which the intake air amount is controlled by a variable valve mechanism without using a throttle valve. The details of the variable valve mechanism will be described later in detail with reference to FIGS.

  A spur-shaped first gear 14 is fixed to the end of the control shaft 12. Similarly, a spur-shaped second gear 16 is engaged with the first gear 14. A rotation shaft 18 is fixed to the center of the second gear 16. Further, as shown in FIG. 1B, a semicircular worm wheel 20 is fixed to the rotary shaft 18 so as to overlap the second gear 16. Further, a worm gear 24 fixed to the rotating shaft of the motor 22 is engaged with the worm wheel 20. According to such a configuration, the rotational position of the control shaft 12 can be controlled by controlling the rotation of the motor 22.

  A rotation angle sensor 26 for detecting the rotational position of the control shaft 12 is also disposed at the end of the control shaft 12. The output of the rotation angle sensor 26 is supplied to an ECU (Electronic Control Unit) 28. The ECU 28 is further connected with a water temperature sensor 29 for detecting the cooling water temperature THW of the internal combustion engine. The ECU 28 can detect the output of the rotation angle sensor 26 and the output of the water temperature sensor 29, and can control the state of the motor 22.

  Further, the relationship between the output of the rotation angle sensor 26 and the actual rotational position of the control shaft 12 is not necessarily limited in all cases due to individual sensor differences, mechanical variations, and their temporal changes. It will not be constant. Under such a premise, the ECU 28 rotates the control shaft 12 to one control end immediately after the internal combustion engine is started, for example (hereinafter, this process is referred to as “butting process”), and the sensor output at that time The function is calibrated based on the output. Therefore, the ECU 28 can accurately detect the rotational position of the control shaft 12 based on the output of the rotation angle sensor 26 without being affected by the above-described change over time or the like.

[Detailed configuration of variable valve mechanism]
Next, the configuration and operation of a mechanical mechanism that the variable valve mechanism of the present embodiment includes for each cylinder will be described. In the following description, for convenience of explanation, the mechanical mechanism is also referred to as a “variable valve mechanism” after being denoted by reference numeral 30. Each cylinder of the internal combustion engine is provided with two intake valves, and each variable valve mechanism 30 drives two intake valves.

  FIG. 2 is a perspective view of the main part of the variable valve mechanism 30 provided corresponding to one cylinder. The variable valve mechanism 30 includes two valve bodies 32 (here, intake valves) to be driven. A valve shaft 34 is fixed to each valve body 32. The end of the valve shaft 34 is in contact with a pivot provided at one end of the rocker arm 36. A biasing force of a valve spring (not shown in FIG. 2) is applied to the valve shaft 34, and the rocker arm 36 is biased upward by the valve shaft 34 that has received the biasing force. The other end of the rocker arm 36 is rotatably supported by a hydraulic lash adjuster 38. According to the hydraulic lash adjuster 38, the tappet clearance can be automatically adjusted by automatically adjusting the position in the height direction of the rocker arm by hydraulic pressure.

  A roller 40 is disposed at the center of the rocker arm 36. A swing arm 42 is disposed on the roller 40. Hereinafter, the structure around the swing arm 42 will be described with reference to FIG.

  FIG. 3 is an exploded perspective view of the first arm member 44 and the second arm member 46. The first arm member 44 and the second arm member 46 are both main components of the variable valve mechanism 30 shown in FIG. The swing arm 42 described above is a part of the first arm member 44 as shown in FIG.

  That is, as shown in FIG. 3, the first arm member 44 is a member integrally including two swing arms 42 and a roller contact surface 48 sandwiched between them. The two swing arms 42 are provided corresponding to the two valve bodies 32, respectively, and are in contact with the rollers 40 (see FIG. 2) described above.

  The first arm member 44 is provided with a bearing portion 50 opened so as to penetrate the two swing arms 42. Each of the swing arms 42 is provided with a concentric circle part 52 and a pressing part 54 on the surface in contact with the roller 40. The concentric circle portion 52 is provided so that the contact surface with the roller 40 forms a concentric circle with the bearing portion 50. On the other hand, the pressing portion 54 is provided such that the distance from the center of the bearing portion 50 increases as the distal end portion thereof is closer.

  The second arm member 46 includes a non-oscillating portion 56 and an oscillating roller portion 58. A through hole is provided in the non-oscillating portion 56, and the control shaft 12 described with reference to FIG. 1 is inserted into the through hole. Furthermore, a fixing pin 62 for fixing the relative position between the non-oscillating portion 56 and the control shaft 12 is inserted. For this reason, the non-oscillating part 56 and the control shaft 12 function as an integral structure.

  The swing roller unit 58 includes two side walls 64. These side walls 64 are connected to a non-oscillating portion 56 via a rotary shaft 66 so as to be rotatable. A cam contact roller 68 and a slide roller 70 are disposed between the two side walls 64. The cam contact roller 68 and the slide roller 70 can freely rotate while being sandwiched between the side walls 64.

  The control shaft 12 described above is a member that is rotatably held by the bearing portion 50 of the first arm member 44. That is, the control shaft 12 is a member that should be integrated with the non-oscillating portion 56 while being held by the bearing portion 50. In order to satisfy this requirement, the non-oscillating portion 56 (that is, the second arm member 46) is positioned between the two oscillating arms 42 of the first arm member 44 before being fixed to the control shaft 12. . The control shaft 12 is inserted so as to pass through the two bearing portions 50 and the non-oscillating portion 56 in a state where the alignment is performed. Thereafter, a fixing pin 62 is attached to fix the control shaft 12 and the non-oscillating portion 56. As a result, the first arm member 44 can freely rotate around the control shaft 12, the non-oscillating portion 56 is integrated with the control shaft 12, and the oscillating roller portion 58 is non-oscillating portion 56. A mechanism capable of swinging with respect to is realized.

  When the first arm member 44 and the second arm member 46 are assembled as described above, the relative angle between the first arm member 44 and the control shaft 12, that is, the first arm member 44 and the non-oscillating portion 56. In the range where the relative angle satisfies the predetermined condition, the slide roller 70 of the swing roller portion 58 can contact the roller contact surface 48 of the first arm member 44. When the first arm member 44 is rotated around the control shaft 12 within a range that satisfies the predetermined condition while maintaining the contact between the two, the slide roller 70 rolls along the roller contact surface 48. Can move. The variable valve mechanism of the present embodiment opens and closes the valve body 32 with the rolling. The operation will be described in detail later with reference to FIG. 4 and FIG.

  FIG. 2 shows a state in which the first arm member 44, the second arm member 46, and the control shaft 12 are assembled according to the above procedure. In this state, the positions of the first arm member 44 and the second arm member 46 are regulated by the rotational position of the control shaft 12. As described above, the motor 22 is connected to the control shaft 12 via the gear mechanism (see FIG. 1). The state shown in FIG. 2 shows a state in which the rotation angle of the control shaft 12 is adjusted by the motor 22 so that the slide roller 70 contacts the roller contact surface 48.

  The variable valve mechanism of this embodiment also includes a camshaft 72 that rotates in synchronization with the crankshaft. Similar to the control shaft 12, the cam shaft 72 is rotatably held by a bearing fixed to the cylinder head 10. A cam 74 provided for each cylinder of the internal combustion engine is fixed to the camshaft 72. In the state shown in FIG. 2, the cam 74 is in contact with the cam contact roller 68 and restricts the upward movement of the swing roller portion 58. That is, in the state shown in FIG. 2, the roller contact surface 48 of the first arm member 44 is mechanically connected to the cam 74 via the cam contact roller 68 and the slide roller 70 of the swing roller portion 58. Is realized.

  According to the state described above, when the cam nose presses the cam contact roller 68 as the cam 74 rotates, the force is transmitted to the roller contact surface 48 via the slide roller 70. The slide roller 70 can continue to transmit the acting force of the cam 74 to the first arm member 44 while rolling on the roller contact surface 48. As a result, the first arm member 44 is rotated about the control shaft 12, the rocker arm 36 is pushed down by the swing arm 42, and the valve body 32 is moved in the valve opening direction. As described above, the variable valve mechanism 30 can operate the valve body 32 by transmitting the acting force of the cam 74 to the roller contact surface 48 via the cam contact roller 68 and the slide roller 70. it can.

[Operation of variable valve mechanism]
Next, the operation of the variable valve mechanism 30 will be described with reference to FIGS. 4 and 5. 4 and 5 show a lost motion spring 76 and a valve spring 78 in addition to the components described above. As described above, the valve spring 78 is a spring for biasing the valve shaft 34 and the rocker arm 36 in the valve closing direction. On the other hand, the lost motion spring 76 is a spring for maintaining the mechanical contact between the roller contact surface 48 and the cam 74.

  That is, the variable valve mechanism 30 drives the valve body 32 by mechanically transmitting the acting force of the cam 74 to the roller contact surface 48 as described above. Therefore, in order for the variable valve mechanism 30 to operate properly, the cam 74 and the roller contact surface 48 are always mechanically connected via the cam contact roller 68 and the slide roller 70. is necessary. In order to satisfy this requirement, it is necessary to urge the roller contact surface 48, that is, the first arm member 44 in the direction of the cam 74.

  The lost motion spring 76 used in the present embodiment is assembled such that its upper end is fixed to a cylinder head or the like and its lower end biases the rear end portion of the roller contact surface 48. In this case, the urging force acts in a direction in which the roller contact surface 48 pushes up the slide roller 70, and further acts as a force for pressing the cam contact roller 68 against the cam 74. As a result, the variable valve mechanism 30 can maintain a state in which the cam 74 and the roller contact surface 48 are mechanically coupled.

  FIG. 4 shows a state in which the variable valve mechanism 30 operates so as to give a small lift to the valve body 32. Hereinafter, this operation is referred to as “small lift operation”. More specifically, FIG. 4A shows a state in which the valve body 32 is closed in the process of the small lift operation, and FIG. 4B shows that the valve body 32 is opened in the process of the small lift operation. The state of speaking is shown respectively.

In FIG. 4A, the symbol θ _C is a parameter representing the rotational position of the control shaft 12. Hereinafter, the parameter is referred to as “control shaft rotation angle θ _C ”. Here, for the sake of convenience, the angle formed by the axial direction of the fixing pin 62 that fixes the control shaft 12 and the non-oscillating portion 56 and the vertical direction is defined as the control shaft rotation angle θ _C. In FIG. 4A, the symbol θ _A is a parameter representing the rotational position of the swing arm 42. Hereinafter, the parameter is referred to as “arm rotation angle θ _A ”. For convenience, and to define the angle between the straight line and the horizontal direction connecting the center of the tip portion and the control shaft 12 of the swing arm 42 and the arm rotation angle theta _A.

In the variable valve mechanism 30, the rotation position of the swing arm 42, that is, the arm rotation angle θ _A is determined by the position of the slide roller 70. Further, the position of the slide roller 70 is determined by the position of the rotating shaft 66 of the swing roller portion 58 and the position of the cam contact roller 68. In the range in which the contact between the cam contact roller 68 and the cam 74 is maintained, the more the rotation shaft 66 rotates counterclockwise in FIG. 4, that is, the greater the control shaft rotation angle θc, The position changes upward. Therefore, in the variable valve mechanism 30 increases the control shaft rotation angle theta _C is, a phenomenon occurs that the arm rotation angle theta _A decreases.

In the state shown in FIG. 4A, the control shaft rotation angle θ _C is within a range in which the cam contact roller 68 can maintain contact with the cam 74, that is, the cam 74 moves upward of the cam contact roller 68. It is almost the maximum value that can be regulated. Therefore, in the state shown in FIG. 4A, the arm rotation angle θ _A is almost the minimum value. In this case, the variable valve mechanism 30 is configured such that the substantially center of the concentric circular portion 52 of the swing arm 42 is in contact with the roller 40 of the rocker arm 36, and as a result, the valve body 32 is closed. . Hereinafter, the arm rotation angle θ _A in this case is referred to as “reference arm rotation angle θ _A0 during small lift”.

When the cam 74 rotates from the state shown in FIG. 4A, the cam contact roller 68 is pressed by the cam nose and moves in the direction of the control shaft 12. Since the distance from the rotation shaft 66 to the slide roller 70 of the swing roller portion 58 does not change, the roller contact surface 48 rolls on the surface when the cam contact roller 68 approaches the control shaft 12. It is pushed down by the slide roller 70. As a result, the swing arm 42 rotates in the direction in which the arm rotation angle θ _A increases, and the contact point between the swing arm 42 and the roller 40 shifts from the vicinity of the center of the concentric circle portion 52 toward the pressing portion 54.

When the pressing portion 54 comes into contact with the roller 40 as the swing arm 42 rotates, the valve element 32 moves in the valve opening direction against the urging force of the valve spring 78. As shown in FIG. 4B, at the timing when the apex of the cam nose comes into contact with the cam contact roller 68, the arm rotation angle θ _A becomes a maximum value (hereinafter referred to as “maximum arm rotation angle θ _AMAX ”). The lift amount of the valve body 32 is maximized. Thereafter, as the cam 74 rotates, the lift amount of the valve body 32 decreases as the arm rotation angle θ _A decreases, and when the contact point between the roller 40 and the swing arm 42 returns to the concentric circle 52. The valve body 32 is closed.

During the small lift operation, since the reference arm rotation angle θ _A0 is set to a small value, the valve body 32 is kept closed for a while after the cam nose starts to contact the cam contact roller 68. Is done. After the maximum lift amount is generated, the valve body 32 returns to the closed state relatively early before the cam nose roller 68 is pressed by the cam nose. As a result, during the small lift operation, the valve element 32 is in a non-closed state, that is, the operating angle of the valve element 32 is a small value, and the maximum lift amount of the valve element 32 is also a small value. Become.

  FIG. 5 shows a state in which the variable valve mechanism 30 is operating so as to give a large lift to the valve element 32. Hereinafter, this operation is referred to as “large lift operation”. More specifically, FIG. 5A shows a state in which the valve body 32 is closed in the process of the large lift operation, and FIG. 5B shows a state in which the valve body 32 is opened in the process of the large lift operation. The state of speaking is shown respectively.

When performing a large lift operation, as shown in FIG. 5A, the control shaft rotation angle θ _C is adjusted to a sufficiently small value. As a result, the arm rotation angle θ _A when not lifted, that is, the reference arm rotation angle θ _A0 is set to a sufficiently large value within a range in which the slide roller 70 does not fall off the roller contact portion 28. The variable valve mechanism 30 is configured such that the contact point between the swing arm 42 and the roller 40 is located at the end of the concentric circle 52 at such a reference arm rotation angle θ _A0 . For this reason, in that state, the valve body 32 is maintained in a closed state.

  When the cam 74 is rotated from the state shown in FIG. 5A, the contact point between the roller 40 and the swing arm 42 is immediately changed from the concentric circle 52 to the pressing portion after the cam contact roller 68 starts to be pressed by the cam nose. 54. The valve body 32 is largely pushed in the valve opening direction until the cam contact roller 68 is pressed against the peak portion of the cam nose. Further, as shown in FIG. 5B, even after the lift of the valve body 32 reaches the maximum amount, the valve body 32 remains open for a long time while the cam nose presses the cam contact roller 68. Maintained. For this reason, according to the variable valve mechanism 30, a large operating angle and a large lift amount can be given to the valve body 32 during the execution of the large lift operation described above.

[Problems of the variable valve mechanism of this embodiment]
As described above, the variable valve mechanism of the present embodiment can change the operating angle and lift amount of the valve body 32 by rotating the control shaft 12. The internal combustion engine in the present embodiment can realize a desired intake air amount by setting the working angle and lift amount to appropriate values, and can realize a desired operation state.

  In order to start the internal combustion engine properly, it is necessary to give the valve body 32 a working angle and a lift amount suitable for the start-up. Since the internal combustion engine is required to exhibit good startability in all assumed operating temperature ranges, when the internal combustion engine is started, an operating angle that can ensure good startability even under the most severe conditions and It is necessary to set the lift amount. In this embodiment, since the minimum value of the operating temperature range of the internal combustion engine is set to “−35 ° C.”, the operating angle and the lift amount at the start are within a range where the internal combustion engine can be started properly in an environment of −35 ° C. Must be controlled. Hereinafter, the operating angle width satisfying the requirement is referred to as “cryogenic start required operating angle width”.

  During operation of the internal combustion engine, an operating angle corresponding to the operating state is realized from moment to moment. For this reason, when the stop of the internal combustion engine is requested, it is normal that the operating angle deviates from the cryogenic start required operating angle width. Therefore, in order to start the internal combustion engine with the working angle within that range, after the stop is requested, before the actual starting is started, the working angle should be within the required working angle width of the cryogenic start. It is necessary to correct the rotational position of the control shaft 12.

  As described above, the variable valve mechanism of the present embodiment includes the rotation angle sensor 26 that detects the rotation position of the control shaft 12. For this reason, the ECU 28 can appropriately correct the rotational position of the control shaft 12 by controlling the motor 22 while observing the output of the rotation angle sensor 26. However, the relationship between the output of the rotation angle sensor 26 and the actual working angle is not necessarily absolute, and is affected by changes over time. For this reason, when adjusting the rotational position of the control shaft 12 when starting the internal combustion engine, it is desirable to control the motor 22 on the basis of a sensor output that is guaranteed to correspond to the actual operating angle. The last time point when the relationship between the output of the rotation angle sensor 26 and the actual operating angle is guaranteed when viewed from the start of the internal combustion engine is the time point when the internal combustion engine is finally stopped. Therefore, when adjusting the rotational position of the control shaft 12 in preparation for starting the internal combustion engine, the output (that is, the working angle) of the rotation angle sensor 26 is detected when the internal combustion engine is stopped, and the output is used as a basis. It is reasonable.

  However, it is normal that the ambient temperature of the variable valve mechanism 30 changes greatly after the internal combustion engine is stopped. For this reason, large thermal deformation is likely to occur around the control shaft 12 and the camshaft 72 after the internal combustion engine is stopped. When such thermal deformation occurs, the relationship between the output of the rotation angle sensor 26 and the actual operating angle of the valve body 32 changes.

  That is, the distance indicated by the reference symbol L in FIG. 4A is the dimension between the control shaft 12 and the camshaft 72. This L dimension becomes smaller as the temperature around the cylinder head 10 decreases after the internal combustion engine is stopped. On the other hand, in the process in which the ambient temperature of the cylinder head 10 decreases, thermal contraction also occurs in the members interposed between the control shaft 12 and the cam shaft 72, that is, the first arm member 44 and the second arm member 46.

  In the present embodiment, the cylinder head 10 is made of a material mainly composed of aluminum, while the first arm member 44 and the second arm member 46 are made of an iron-based material. Since these materials exhibit different linear expansion coefficients, when the ambient temperature of the cylinder head 10 decreases, the L dimension contracts more than the first arm member 44 and the second arm member 46.

That is, in the variable valve mechanism 30 of the present embodiment, the same situation as when the L dimension is substantially reduced due to a decrease in the ambient temperature of the cylinder head 10 after the internal combustion engine is stopped. As a result, the swing arm 42 is rotated in the direction of arm rotation angle theta _A increases, occurs a phenomenon that the actual operating angle of the valve body 12 increases.

  FIG. 6 is a diagram in which the relationship between the temperature drop of the internal combustion engine and the actual operating angle change of the valve body 32 is arranged. In FIG. 6, point A corresponds to the state of temperature t0 and actual working angle A. The temperature t0 is the ambient temperature of the variable valve mechanism 30 during operation of the internal combustion engine. In FIG. 6, a solid straight line drawn so as to pass through the point A indicates a relationship established between the temperature and the actual working angle after the rotational position of the control shaft 12 is fixed at the point A. It is a thing. According to this relationship, after the internal combustion engine is stopped in the state of the temperature t0 and the actual working angle A, the control shaft 12 is not moved, and the temperature of the internal combustion engine is the lowest temperature within the use range (here, −35 ° C. )), The relationship between the temperature and the actual working angle shifts from point A to point B.

  The “cryogenic start required operating angular width” indicated by two horizontal broken lines in FIG. 6 is an optimal operating angular width for starting the internal combustion engine satisfactorily in a cryogenic environment of −35 ° C. In order to always start the internal combustion engine well within the operating temperature range, the internal combustion engine start-up process (queuing) is performed in a state where the actual operating angle of the valve element 32 is within the “cryogenic start required operating angle width”. (Ranking) should be started. For example, when the relationship between the temperature and the actual operating angle corresponds to point B shown in FIG. 6, the rotational position of the control shaft 12 is adjusted so that the actual operating angle B falls within the cryogenic start required operating angle width. It is desirable to start cranking later.

  However, no change occurs in the rotational position of the control shaft 12 in the process in which the relationship between the temperature and the actual operating angle changes from the point A to the point B. For this reason, even if the actual operating angle changes from A to B after the internal combustion engine is stopped, if the change is caused only by a change in temperature, any change occurs in the output of the rotation angle sensor 26. Absent. In this case, assuming that the actual working angle is recognized based only on the output of the rotation angle sensor 28, the working angle which is originally B is A when restarting at an extremely low temperature (−35 ° C.). The situation is mistaken.

  When the operating angle is actually A, the actual operating angle is set to the extreme by adjusting the rotational position of the control shaft 12 so that the operating angle becomes larger by the difference between the A and the cryogenic start required operating angle width. The value C can be set to fall within the required cold start operating angle range. However, under the situation where the actual working angle is B, if the same adjustment is made assuming that the value is A, the actual working angle becomes a value D that is larger than B by (C−A) ( (See broken line in FIG. 6).

  On the other hand, since the dependence of the actual working angle on the temperature can be experimentally grasped in advance, if the temperature t0 when the internal combustion engine is stopped is known, the temperature of the internal combustion engine is extremely low ( The amount of change (B−A) that occurs in the actual working angle in the process of decreasing to −35 ° C. can be obtained as a function of the temperature variation range “t0 − (− 35)”. Then, if both the actual operating angle A when the internal combustion engine is stopped and the amount of change (B−A) are known, by adding both, the cryogenic temperature realized when the control shaft 12 is fixed can be obtained. The actual operating angle B can be obtained. Further, if the actual operating angle B is known, a correction value ΔVL for making the value B a value E that falls within the cryogenic start required operating angle width can be calculated.

  If the control shaft 12 is adjusted so that the actual operating angle A becomes a value F that is smaller by ΔVL when the internal combustion engine is stopped, the internal combustion engine temperature becomes extremely low (−35 ° C.) after that. Thus, it is possible to create a state where the actual operating angle E falls within the required operating angle width of the cryogenic start. In this case, when restarting at an extremely low temperature, it is possible to start the internal combustion engine satisfactorily by simply starting cranking without adjusting the rotational position of the control shaft 12 at all. Therefore, in the present embodiment, the ECU 28 detects the actual operating angle A (output of the rotation angle sensor 26) and the temperature t0 (output of the water temperature sensor 29) when the internal combustion engine is stopped, and corrects based on the detected values. The value ΔVL is calculated, and the rotational position of the control shaft 12 is adjusted so that the correction value ΔVL is generated at the operating angle.

  FIG. 7 is a flowchart of a routine executed by the ECU 28 in order to realize the above function. Note that this routine is a routine that is started when the internal combustion engine is started. In this routine, first, the actual working angle A is detected based on the output of the rotation angle sensor 26, and the cooling water temperature THW is detected based on the output of the water temperature sensor 29. Here, THW detected in this way is treated as the engine temperature t0, that is, the ambient temperature of the variable valve mechanism 30 (step 100).

  Next, it is determined whether or not a stop of the internal combustion engine has been requested (step 102). Specifically, it is determined whether or not the ignition switch of the vehicle has been switched from ON to OFF. As a result, when it is determined that a stop request has not occurred, the process of step 100 is executed again. On the other hand, if it is determined that the stop request has occurred, then, the restart temperature of the internal combustion engine, specifically, “−35 ° C.” that is the lowest temperature in the operating temperature range, and the current engine temperature, that is, Then, the difference Δt = t0 − (− 35 ° C.) from the stop-time temperature t0 is calculated (step 104).

  Next, the non-corrected restart operating angle B (see FIG. 6) is calculated. Specifically, when the ambient temperature of the variable valve mechanism 30 is lowered to the assumed restart temperature without correcting the rotational position of the control shaft 12, the operating angle that is actually expected to be generated, that is, the current When the state of the control shaft 12 is maintained, an operating angle that is predicted to occur in an extremely low temperature (−35 ° C.) environment is calculated (step 106). The ECU 28 stores a map or an arithmetic expression (for example, a linear expression such as y = ax + b) corresponding to the relationship between the temperature and the actual working angle as shown in FIG. In this step 106, the actual working angle A at the time of stop and the temperature difference Δt = t0 − (− 35 ° C.) are applied to the relationship, thereby calculating the non-corrected restart working angle B.

  Next, a correction value ΔVL (see FIG. 6) is calculated (step 108). Specifically, a correction value ΔVL for keeping the non-corrected restart operating angle B within the cryogenic start required operating angle width is calculated. The ECU 28 stores in advance the median value E of the cryogenic start required operating angle width, and calculates the correction value ΔVL by performing the calculation “B−E”.

  Next, a process for reducing the stop operating angle A by the correction value ΔVL and realizing the stop target operating angle F (see FIG. 6) is performed (step 110). Specifically, a process of driving the motor 22 is performed to adjust the rotational position of the control shaft 12 so that the actual operating angle is reduced by the correction value ΔVL.

  When the above processing is completed, the operation angle control processing is stopped, and the routine shown in FIG. 7 is terminated. According to the above processing, when the internal combustion engine is stopped, the actual operating angle A is set to the target operating angle F at the time of stopping in anticipation of the ambient temperature of the variable valve mechanism 30 subsequently decreasing to an extremely low temperature (−35 ° C.). Can be changed. In this case, if the ambient temperature of the variable valve mechanism 30 actually decreases to a very low temperature before the internal combustion engine is restarted, cranking is performed using the actual operating angle E that falls within the cryogenic start required operating angle width. Can start.

  For this reason, according to the variable valve mechanism 30 of the present embodiment, it is possible to always give a good startability to the internal combustion engine in a cryogenic environment. The startability of the internal combustion engine becomes better as the temperature at the start is higher. For this reason, according to the conditions under which good startability is obtained in an extremely low temperature environment, good startability can be realized in all temperature ranges. Therefore, according to the variable valve mechanism 30 of the present embodiment, the internal combustion engine can be restarted satisfactorily under any environment.

  Further, according to the above-described method of operating angle control, when the internal combustion engine is stopped, the rotational position adjustment of the control shaft 12 in preparation for restart can be finished. In this case, at the time of restart, cranking can be promptly started without changing the state of the control shaft 12. For this reason, according to the variable valve mechanism of the present embodiment, after the restart of the internal combustion engine is requested, cranking necessary for the start can be started without a sense of incongruity.

  However, the rotational position adjustment of the control shaft 12 in preparation for restart is not limited to being performed when the internal combustion engine is stopped. That is, the rotational position adjustment may be performed when restart of the internal combustion engine is requested. FIG. 8 is a diagram for explaining the processing procedure in this case. Assuming that the rotational position of the control shaft 12 is adjusted at the time of the start request, the actual operating angle of the valve body 32 is along a straight line passing through the point A shown in FIG. Change. When the ambient temperature of the variable valve mechanism 30 decreases to an extremely low temperature, the actual operating angle becomes B.

  Regardless of whether the rotational position of the control shaft 12 is adjusted at the time of stop or start, if the stop temperature t0 and the stop operating angle A are detected, the correction value is obtained by the above method. ΔVL can be calculated. For this reason, when the internal combustion engine is stopped or started, the correction value ΔVL is calculated by the method, and when the rotation position of the control shaft 12 is adjusted by the correction value ΔVL when the internal combustion engine is started, Immediately after the occurrence, the actual working angle can be changed from B to E, that is, a situation can be created in which the actual working angle falls within the cryogenic start required working angle width. Then, if cranking is started after the situation is formed, a variable valve that can give good startability to the internal combustion engine under all temperature environments, as in the first embodiment. A mechanism can be realized.

  By the way, in Embodiment 1 mentioned above, although the mechanism which changes the working angle and lift amount of the valve body 32 by rotating the control shaft 12 is used, this invention is not limited to this. That is, the variable valve mechanism that changes the operating angle and lift amount of the valve body 32 may be changed by moving the control shaft 12 in the axial direction.

  In the first embodiment described above, the variable valve mechanism 30 changes both the operating angle and the lift amount according to the state of the control shaft 12, but the present invention is limited to this. It is not a thing. That is, the variable valve mechanism may change only one of the operating angle and the lift amount. In that case, the adjustment of the control shaft 12 in preparation for restarting the internal combustion engine may be performed by paying attention only to the value of the change in the operating angle and the lift amount.

  In the first embodiment described above, the first arm member 44 and the second arm member 46 are the “variable mechanism” in the first invention, and the water temperature sensor 29 is the “temperature detecting means” in the first invention. In addition, the rotation angle sensor 26 corresponds to the “state detection sensor” in the first invention, and the ECU 28 detects the engine temperature t0 in the above step 100, thereby detecting “stop” in the first invention. The “temporal temperature acquisition means” detects the actual operating angle A, so that the “stop characteristic value detection means” executes the processing of step 106 described above, whereby the “non-correction restart characteristic value” in the first invention. When the “calculation means” executes the process of step 108, the “correction value calculation means” in the first invention executes the process of step 110. Ri said "pre-start correction means" in the first aspect of the present invention are realized, respectively.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The variable valve mechanism of the present embodiment is structurally similar to the variable valve mechanism of the first embodiment. The variable valve mechanism of this embodiment has characteristics suitable for use in combination with an internal combustion engine having an automatic stop / automatic start function, such as an eco-run vehicle having a so-called idling stop function or a hybrid vehicle. Hereinafter, the case where the variable valve mechanism of the present embodiment is used in combination with a vehicle having an automatic stop / automatic start function will be described.

  FIG. 9 is a view for explaining a control method of the control shaft 12 used in the variable valve mechanism of the present embodiment. In FIG. 9, the straight line indicated by the alternate long and short dash line is a relationship that is established between the ambient temperature of the variable valve mechanism 30 and the actual operating angle when the rotational position of the control shaft 12 is fixed at a position passing through point A. It represents. Since the variable valve mechanism 30 of the present embodiment has the same configuration as in the first embodiment, the actual operating angle of the valve element 32 has the same temperature characteristics as in the first embodiment. appear. For this reason, after the internal combustion engine is stopped, even if the rotational position of the control shaft 12 is fixed, the actual operating angle of the valve body 32 changes as the engine temperature decreases.

  In eco-run vehicles and hybrid vehicles, the automatic stop and automatic start of the internal combustion engine are frequently repeated. Further, in these vehicles, it is required to automatically start the internal combustion engine without feeling uncomfortable. In order to satisfy such a requirement, it is necessary to control the actual working angle of the valve body 32 to a value that can sufficiently suppress vibration and the like when the internal combustion engine is started.

  “Restart required operating angle width” indicated by two horizontal broken lines in FIG. 9 is the operating angle width satisfying such a requirement. This restart required operating angle width is a width of an operating angle suitable for starting the internal combustion engine, so that the actual operating angle is usually out of the width while the internal combustion engine is required to perform normal operation. is there. For this reason, the internal combustion engine is often stopped in a state where the actual operating angle deviates from the restart required operating angle width (for example, the state of the actual operating angle A). In order to obtain a good startability, the rotational position of the control shaft 12 is set so that the actual operating angle A falls within the restart required operating angle width after the stop until the restart is attempted. It is necessary to adjust.

  The better the response of the internal combustion engine to the start request, the better. In particular, in an eco-run vehicle or a hybrid vehicle that is frequently started and stopped, good responsiveness is particularly desired. In order to improve the responsiveness to the start, it is desirable that the adjustment work for keeping the actual operating angle within the restart request operating angle width is completed before the start request is generated. For this reason, in the present embodiment, as indicated by a solid line (including an arrow) in FIG. 9, after the internal combustion engine is stopped, the actual operating angle A immediately changes to a value within the restart required operating angle width, After that, while the internal combustion engine is stopped, the rotational position of the control shaft 12 is adjusted so that the actual operating angle remains within the restart required operating angle width regardless of the temperature change. In this case, no matter what timing the automatic start of the internal combustion engine is requested, the actual operating angle is always within the restart required operating angle range. It is possible to realize.

  FIG. 10 is a flowchart of a routine executed by the ECU 28 in the present embodiment in order to realize the above function. In addition, this routine shall be a routine started when the system of an eco-run vehicle or a hybrid vehicle is started. In this routine, first, the actual working angle A is detected based on the output of the rotation angle sensor 26, and the cooling water temperature THW is detected based on the output of the water temperature sensor 29. Here, THW detected in this way is treated as the engine temperature t0, that is, the ambient temperature of the variable valve mechanism 30 (step 120).

  Next, it is determined whether or not a stop of the internal combustion engine has been requested (step 122). As a result, when it is determined that the stop of the engine is not requested, the process of step 120 is executed again. On the other hand, if it is determined that the stop of the engine is requested, it is further determined whether or not the stop of the vehicle system itself is requested (step 124). If it is determined that the stop of the vehicle system itself is requested, then the current processing cycle is immediately terminated. On the other hand, if it is determined that the stop of the vehicle system itself is not requested, it is next determined whether or not the restart of the internal combustion engine is requested (step 126).

  The system of the present embodiment automatically stops the internal combustion engine when a stop of the internal combustion engine is requested, and then automatically starts the internal combustion engine when a restart of the internal combustion engine is requested. Therefore, after the request for stopping the engine is accepted in step 122, the internal combustion engine is maintained in a stopped state until the request for restart is accepted in step 126. During this time, the ambient temperature of the variable valve mechanism 30 decreases from moment to moment. On the other hand, the processing after step 128 described below is executed in the ECU 28.

  That is, in this case, the ECU 28 first detects the current coolant temperature THW as the temperature t1 during which the internal combustion engine is stopped (step 128). Next, the difference between the stopping temperature t0 detected in step 120 and the stopping temperature t1, that is, the temperature difference Δt = t0−t1 generated in the ambient temperature of the variable valve mechanism 30 after the internal combustion engine is stopped. Is calculated (step 130).

  Next, due to the temperature difference Δt, a working angle change amount ΔA that is expected to occur in the actual working angle after the internal combustion engine is stopped is calculated (step 132). The ECU 28 stores a map or an arithmetic expression (for example, a linear expression such as y = ax + b) corresponding to the relationship between the temperature and the actual working angle as shown in FIG. In step 132, the operating angle change amount ΔA is calculated by applying the temperature difference Δt = t0−t1 to the relationship.

  Next, it is determined whether A + ΔA is equal to or greater than the lower limit value α of the restart required operating angle width and equal to or lower than the upper limit value β of the restart required operating angle width (step 134). If there is a change in ΔA in the actual operating angle after the internal combustion engine is stopped, the actual operating angle at the present time can be estimated to be a value A + ΔA obtained by adding the operating angle change amount ΔA to the operating angle A at the time of stop. Specifically, it is determined whether or not the actual operating angle A + ΔA is within the restart required operating angle width.

  When the internal combustion engine is stopped, the actual operating angle A often deviates from the restart required operating angle width. Immediately after the stop, there is not a working angle change amount ΔA enough to offset the deviation between the actual working angle A and the restart required working angle width. For this reason, the condition of step 134 is usually not satisfied at such timing. In this case, the difference between the latest actual operating angle A + ΔA and the median value of the restart required operating angle width is calculated as a correction value ΔVL = (A + ΔA) − {(α + β) / 2} (step 136).

  Next, the actual operating angle is changed by the correction value ΔVL, and the rotational position of the control shaft 12 is adjusted so that the new actual correction angle becomes (A + ΔA−ΔVL). The actual operating angle “A + ΔA−ΔVL” realized as a result is stored as the latest actual operating angle A (step 138). Further, when the above adjustment is performed, the stopped temperature t1 detected at that time is stored again as a new temperature t0 (step 140). Thereafter, the processing after step 124 is executed again.

  According to the above processing, immediately after the internal combustion engine is automatically stopped, the actual operating angle A can be quickly changed to the median value of the restart required operating angle width. Then, the latest actual operating angle after the change can be stored as a new A, and the temperature at the time when the change has occurred can be stored as a new t0.

  As long as the system of the eco-run vehicle or the hybrid vehicle is not stopped and the restart of the internal combustion engine is not required, the processes of steps 128 to 140 described above are repeated. In this case, in step 130, the difference between the temperature t0 when the control shaft 12 is adjusted and the current stopped temperature t1 is calculated as the temperature difference Δt. In step 134, a value obtained by adding the operating angle change amount ΔA generated after the adjustment to the actual operating angle A realized by the adjustment of the control shaft 12 is calculated as the latest actual operating angle A + ΔA. It is determined whether or not the value A + ΔA is within the restart request operating angle range.

  Immediately after the adjustment of the control shaft 12, since a large operating angle change amount ΔA does not occur after the adjustment, the latest actual operating angle A + ΔA is within the restart required operating angle width. In this case, it is determined in step 134 that the condition is satisfied, and thereafter, the processing after step 124 is performed again. When a sufficient time has elapsed after the adjustment of the control shaft 12, the latest actual operating angle A + ΔA deviates from the restart required operating angle width as the stopped temperature t1 decreases. In this case, the condition of step 134 is not satisfied, and the rotational position of the control shaft 12 is adjusted again (steps 136 to 140).

  As a result of the above processing being repeated, the actual operating angle is always within the restart required operating angle width during the automatic stop of the internal combustion engine. For this reason, according to the variable valve mechanism of the present embodiment, when the restart is requested after the internal combustion engine is automatically stopped, it is possible to realize a good restart with excellent responsiveness. . According to the routine shown in FIG. 10, after the restart of the internal combustion engine is requested, it is determined that the condition of step 126 is satisfied, and thereafter, the processing after step 120 is repeated again.

  By the way, in the second embodiment described above, from the viewpoint of giving priority to the responsiveness at the time of restart, the actual operating angle is always kept within the restart required operating angle width while the internal combustion engine is stopped. Is not limited to this. That is, the actual operating angle may be within the restart request operating angle width when restarting is requested. FIG. 11 is a diagram for explaining the processing procedure in this case. If the actual working angle is corrected at the time of the start request, the actual working angle changes along a straight line passing through the point A shown in FIG. 11 in the process of lowering the engine temperature after the internal combustion engine is stopped.

  In this case, if the temperature t1 at the restart request is known in addition to the stop operating angle A and the stop temperature t0, the actual operating angle B at the restart request can be obtained. If the actual operating angle B at that time is known, the correction value ΔVL for keeping the actual operating angle B within the restart required operating angle width can also be obtained by calculation. For this reason, while the internal combustion engine is stopped, only the calculation process of the correction value ΔVL is repeatedly executed. When the restart is requested, the control shaft 12 for realizing the correction value ΔVL is realized prior to the start of cranking. It is possible to obtain a good startability even if only the adjustment is performed.

  Furthermore, if the time required for calculating the correction value ΔVL is not so much affected by the responsiveness at the start, no processing is performed while the internal combustion engine is stopped, and when the restart of the internal combustion engine is requested. The calculation of the correction value ΔVL based on the temperature t1 at that time and the control of the control shaft 12 for realizing the correction value ΔVL may be sequentially executed, and then cranking may be started. Also by such a method, it is possible to achieve restart at an appropriate actual working angle, and it is possible to impart good startability to the internal combustion engine.

  In the second embodiment described above, the variable valve mechanism is combined with an internal combustion engine having functions of automatic stop and automatic start, such as an eco-run vehicle and a hybrid vehicle. It is not limited. That is, the present invention seeks to realize an optimum operating angle and lift amount suitable for starting under the actual engine temperature t1 at the time when the starting of the internal combustion engine is requested. Such a variable valve mechanism is also useful for improving the startability of a normal internal combustion engine.

  In the second embodiment described above, the first arm member 44 and the second arm member 46 are the “variable mechanism” in the fourth invention, and the water temperature sensor 25 is the “temperature detecting means” in the fourth invention. The rotation angle sensor 22 corresponds to the “state detection sensor” in the fourth aspect of the invention. Further, here, the ECU 24 detects the actual operating angle A and the engine temperature t0 in the above step 120, whereby the “characteristic value detecting means at stop” and the “temperature acquiring means at stop” in the fourth invention are By detecting the stopped temperature t1 in step 128, the “stopped temperature acquisition means” in the fourth invention is executed, and by executing the processing of step 138, the “stopped correction means” in the fourth invention is executed. , Each has been realized.

  In the second embodiment described above, the ECU 24 executes the processing of steps 130 and 132 immediately after the internal combustion engine is stopped, so that the “first characteristic value fluctuation amount calculating means” in the fifth aspect of the invention is By calculating A + ΔA in step 134 immediately after the internal combustion engine is stopped, the “first actual characteristic value calculating means” in the fifth aspect of the invention performs the determination of α ≦ A + ΔA ≦ β in step 134. In the fifth invention, the “appropriate judgment means” drives the control shaft 12 in step 138, so that the “control axis correction means” in the fifth invention sets A + ΔA−ΔVL to a new actual operating angle in step 138. By calculating as A, the “corrected characteristic value calculating means” in the fifth aspect of the present invention performs the above step after the control shaft 12 is corrected. By executing the processes 130 and 132, the “second characteristic value fluctuation amount calculating means” in the fifth aspect of the present invention calculates A + ΔA in step 134 after the correction of the control shaft 12 is performed. The “second actual characteristic value calculating means” in the fifth invention is realized.

  In the above-described second embodiment, the first arm member 44 and the second arm member 46 are the “variable mechanism” in the seventh invention, and the water temperature sensor 25 is the “temperature detecting means” in the sixth invention. The rotation angle sensor 22 corresponds to the “state detection sensor” in the seventh aspect of the invention. Further, here, the ECU 24 detects the engine temperature t0 and the actual operating angle A in the above-described step 120, whereby the “stop-time temperature acquisition means” and the “stop-time characteristic value detection means” in the sixth invention are provided. Each can be realized. In addition, by causing the ECU 24 to detect the engine temperature when the restart request is generated, the “restart request temperature acquisition means” in the sixth aspect of the present invention is set so that the actual operating angle A + ΔA ( In the sixth aspect of the invention, the "uncorrected restart request characteristic value calculating means" in the sixth aspect of the invention is calculated, and then the processing of step 136 is executed. By causing the “correction value calculation means” to execute the processing of step 138, the “pre-restart correction means” according to the sixth aspect of the present invention can be realized.

It is a figure for demonstrating the whole structure of the variable valve mechanism of Embodiment 1 of this invention. It is a perspective view of the mechanical mechanism (variable valve mechanism) with which the variable valve mechanism of Embodiment 1 of this invention is provided corresponding to one cylinder. It is a disassembled perspective view of the 1st arm member and 2nd arm member which are the components of the variable valve mechanism shown in FIG. It is a figure which shows a mode in case the variable valve mechanism of Embodiment 1 of this invention performs a small lift operation | movement. It is a figure which shows a mode in case the variable valve mechanism of Embodiment 1 of this invention performs a large lift operation | movement. It is a characteristic view for demonstrating operation | movement of the variable valve mechanism of Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a characteristic view for demonstrating operation | movement of the modification of the variable valve mechanism of Embodiment 1 of this invention. It is a characteristic view for demonstrating operation | movement of the variable valve mechanism of Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a characteristic view for demonstrating operation | movement of the modification of the variable valve mechanism of Embodiment 2 of this invention.

Explanation of symbols

12 Control shaft 22 Motor 32 Valve body 32 Swing arm 44 First arm member 46 Second arm member 72 Cam shaft 74 Cam θ _C Control shaft rotation angle θ _A Arm rotation angle

Claims (7)

A variable valve mechanism having a function of changing the operating angle and / or lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
Non-corrected restart characteristic value calculation means for calculating a non-corrected restart characteristic value based on the difference between the assumed restart temperature of the internal combustion engine and the stop temperature, and the stop characteristic value;
Correction value calculating means for calculating a correction value for converting the non-corrected restart characteristic value into a working angle and / or lift amount suitable for the assumed restart temperature;
A pre-start correction means for correcting the state of the control shaft so that a change in the correction value occurs in the operating angle and / or the lift amount prior to restarting the internal combustion engine;
A variable valve mechanism comprising:   2. The variable valve mechanism according to claim 1, wherein the pre-start correction means performs the correction when the internal combustion engine is stopped.   3. The variable valve mechanism according to claim 1, wherein the assumed restart temperature is a minimum temperature within a use temperature range of the internal combustion engine. A variable valve mechanism having a function of changing the operating angle and / or lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
A temperature-in-stop acquisition means for acquiring the temperature in the vicinity of the internal combustion engine as the temperature during stop;
Based on the stop temperature, the stop characteristic value, and the stop temperature, the operating angle and / or lift amount during stop of the internal combustion engine are maintained at values suitable for restart. A stopping correction means for correcting the state;
A variable valve mechanism comprising: The stopping correction means includes:
First characteristic value fluctuation amount calculating means for calculating a first characteristic value fluctuation amount based on a difference between the temperature at the time of stop and the temperature during the stop;
First actual characteristic value calculation means for calculating a sum of the characteristic value at the time of stop and the first characteristic value fluctuation amount as an actual characteristic value;
Appropriate judgment means for judging whether or not the calculated actual characteristic value is a value suitable for restart;
Control axis correction means for correcting the state of the control axis so that the actual characteristic value becomes a value suitable for restarting when it is determined that the actual characteristic value is not suitable for restarting;
A corrected characteristic value calculating means for calculating a corrected characteristic value realized by correcting the control axis;
Second characteristic value fluctuation amount calculating means for calculating a second characteristic value fluctuation amount based on a temperature difference generated in the temperature during stop after the correction of the control axis;
Second actual characteristic value calculating means for calculating a sum of the corrected characteristic value and the second characteristic value fluctuation amount as an actual characteristic value;
The variable valve mechanism according to claim 4, comprising: A variable valve mechanism having a function of changing the operating angle and / or lift amount of a valve body of an internal combustion engine,
A control shaft whose state is controlled to change the working angle and / or lift amount;
A swing arm that is interposed between the cam and the valve body and swings in synchronization with the rotation of the cam to transmit the pressing force of the cam to the valve body;
A variable mechanism that changes a basic relative angle of the swing arm with respect to the valve body according to a state of the control shaft;
Temperature detecting means for detecting or estimating the temperature in the vicinity of the control shaft and the cam;
A state detection sensor for detecting the state of the control axis;
A stop-time temperature acquisition means for acquiring the temperature near the stop when the internal combustion engine is stopped as a stop-time temperature;
A stop characteristic value detecting means for detecting a working angle and / or lift amount when the internal combustion engine is stopped as a stop characteristic value based on the state of the control shaft;
Restart request temperature acquisition means for acquiring the temperature near the restart time of the internal combustion engine as a restart request temperature;
A non-correction restart request time characteristic value calculating means for calculating a non-correction restart request time characteristic value based on the difference between the restart request temperature and the stop temperature, and the stop characteristic value;
Correction value calculating means for calculating a correction value for converting the non-correction restart request time characteristic value into a characteristic value suitable for restart;
Pre-restart correction means for correcting the state of the control shaft so that the correction value changes in the operating angle and / or lift amount prior to restarting the internal combustion engine;
A variable valve mechanism comprising:   The variable valve mechanism according to any one of claims 4 to 6, wherein the internal combustion engine has a function of automatically stopping and starting without depending on a driver's operation.

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