JP2009209714A - Actuator for variable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize excessive rotation due to torsion of a control shaft when suppressing rotation of a control shaft in a variable valve mechanism by a stopper means. <P>SOLUTION: One axial end side of a control shaft 15 which is rotated by an electric motor 21 to actuate a variable valve mechanism contains a worm 22 and worm wheel 23 for transmitting driving force of the electric motor 21 to the control shaft 15, and a first and second stopper members 42, 43 for controlling a turnable range of the control shaft 15. The torsion of the control shaft 15 is suppressed by arranging the worm 22 and worm gear 23 and the first and second stopper members 42, 43 close to each other as much as possible. As a result, excessive rotation of the control shaft 15 is minimized. Since the first stopper member 43 is integrated with the worm wheel 23, in particular, the rotation of the control shaft 15 including the worm wheel 23 is surely prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an actuator for a variable valve mechanism that operates at least a valve lift of an internal combustion engine by operating a variable valve mechanism with a control shaft that is connected to an electric motor and rotates.

A stopper means for supporting the control shaft of the variable valve mechanism on the cylinder head of the internal combustion engine, connecting an actuator for rotationally driving the control shaft to one end thereof, and mechanically restricting the rotatable range of the control shaft to the other end Is known from Patent Document 1 below.
JP-A-9-268906

  By the way, the above-mentioned conventional one is provided with actuators and stopper means at both ends of the control shaft, so that when the pivotable range of the control shaft is mechanically restricted by the stopper means, it is at a position far from the stopper means. The control shaft is twisted by the torque of the actuator, and there is a problem that it is difficult to accurately regulate the rotatable range of the control shaft.

  The present invention has been made in view of the above circumstances, and an object thereof is to minimize excessive rotation due to twisting of the control shaft when the rotation of the control shaft of the variable valve mechanism is suppressed by the stopper means. .

  In order to achieve the above object, according to the first aspect of the present invention, a variable valve mechanism that operates at least a valve lift of an internal combustion engine by operating a variable valve mechanism with a control shaft that is connected to an electric motor and rotates. In the valve mechanism actuator, driving force transmitting means for transmitting the driving force of the electric motor to the control shaft on one shaft end side of the control shaft, and stopper means for restricting a rotatable range of the control shaft; There is proposed a variable valve mechanism actuator characterized in that

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the driving force transmitting means is provided on the worm rotated by the electric motor and the control shaft and meshes with the worm. A variable valve mechanism including a worm wheel, wherein the stopper means includes a first stopper member provided on the worm wheel and a second stopper member with which the first stopper member can abut. Actuators are proposed.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect, the first stopper member is integrally formed on the axial end surface of the worm wheel. A mechanism actuator is proposed.

  According to the invention described in claim 4, in addition to the configuration of claim 2 or claim 3, a sensor for detecting the rotational position of the control shaft is provided at one shaft end of the control shaft, A variable valve mechanism actuator is proposed in which the first stopper member is disposed between the worm wheel and the sensor.

  According to a fifth aspect of the present invention, in addition to the configuration of any one of the second to fourth aspects, an actuator housing that houses the worm is disposed below the control shaft, and the actuator An actuator for a variable valve mechanism is proposed in which the second stopper member is provided in a housing.

  The rotation angle sensor 20 of the embodiment corresponds to the sensor of the present invention, the worm 22 and the worm wheel 23 of the embodiment correspond to the driving force transmission means of the present invention, and the first and second stoppers of the embodiment. The members 42 and 43 correspond to the stopper means of the present invention.

  According to the configuration of the first aspect, the driving force transmitting means for transmitting the driving force of the electric motor to the control shaft is provided on one shaft end side of the control shaft that is rotated by the electric motor to operate the variable valve mechanism. Since the stopper means that regulates the pivotable range of the shaft is provided, the drive force transmission means and the stopper means are brought as close as possible to suppress the twisting of the control shaft and minimize the excessive rotation of the control shaft Can be suppressed.

  According to the second aspect of the present invention, the driving force transmitting means is composed of a worm that is rotated by an electric motor and a worm wheel that is provided on the control shaft and meshes with the worm, and the stopper means is provided on the worm wheel. Since the first stopper member and the second stopper member with which the first stopper member can come into contact are configured, the first and second stopper members are brought into contact with each other to reliably rotate the control shaft provided with the worm wheel. Can be prevented.

  According to the third aspect of the present invention, since the first stopper member is integrally formed on the end face in the axial direction of the worm wheel, not only the number of parts can be reduced, but also the rigidity of the worm wheel and the first stopper member can be increased mutually. Can fit.

  According to the fourth aspect of the present invention, the sensor for detecting the rotational position is provided at one shaft end of the control shaft, and the first stopper member is disposed between the worm wheel and the sensor. The portion twisted by the load applied to the first stopper member is limited between the first stopper member and the worm wheel, and no twist is generated between the first stopper member and the sensor. The position detection accuracy can be ensured to the maximum.

  According to the fifth aspect of the present invention, since the actuator housing for storing the worm is disposed below the control shaft and the second stopper member is provided on the actuator housing, the special member for providing the second stopper member is provided. It becomes unnecessary and can reduce the number of parts.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 9 show a first embodiment of the present invention. FIG. 1 is a plan view of a cylinder head of a multi-cylinder engine having a variable valve mechanism, and FIG. 2 is a line 2-2 in FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, FIG. 5 is a sectional view taken along line 5-5 in FIG. 6 is a sectional view taken along line 7-7 of FIG. 2, FIG. 8 is a sectional view taken along line 8-8 of FIG. 2, and FIG. 9 is a sectional view taken along arrow 9 of FIG.

  As shown in FIG. 1, a cylinder head 11 of an in-line multi-cylinder engine is provided with two intake valves 13 for opening and closing combustion chambers 12 formed on the lower surface thereof. The valve lift and / or valve timing is controlled by a variable valve mechanism 14 provided for each cylinder. Various structures are known as the variable valve mechanisms 14... The present invention can employ the variable valve mechanisms 14. A control shaft 15 is disposed on the upper surface of the cylinder head 11 along the arrangement direction of the plurality of variable valve mechanisms 14... The variable valve mechanisms 14 are formed by cams 15 a provided at predetermined intervals on the control shaft 15. Is controlled.

  An actuator 16 that drives the control shaft 15 is provided on the upper surface of one end in the longitudinal direction of the cylinder head 11. The actuator 16 includes an actuator housing 18 fixed to the upper surface of the cylinder head 11 with four bolts 17A, 17A; 17B, 17B, and one end portion of the control shaft 15 is a bearing portion provided in the vicinity of the actuator housing 18. 19 is rotatably supported. A rotation angle sensor 20 that detects the rotational position of the control shaft 15 that protrudes from the end wall of the cylinder head 11 is provided.

  An electric motor 21 is supported on the side wall of the cylinder head 11 in a direction perpendicular to the control shaft 15 when viewed in a direction perpendicular to the paper surface. A worm 22 (see FIG. 2) provided on a motor output shaft 29 of the electric motor 21 is supported. Meshing with a worm wheel 23 provided on the control shaft 15, the control shaft 15 is driven to rotate by the driving force of the electric motor 21.

  As apparent from FIGS. 1 to 3, a plate-like first stopper member 42 is integrally formed on the axial end surface of the worm wheel 23, and the integrated worm wheel 23 and the first stopper member 42 are formed as a single member. The flange 15b formed integrally with the end of the control shaft 15 is fixed with three bolts 41A, 41B, and 41C arranged around the control shaft 15 at intervals of 120 °.

  The first stopper member has a symmetrical shape with respect to the symmetry plane P (see FIG. 3), and includes two planar stopper surfaces 42a and 42b that are symmetrical with respect to the symmetry plane P. The three bolts 41A, 41B, 41C are arranged asymmetrically with respect to the symmetry plane P. That is, in FIG. 3, the three bolts 41A, 41B, 41C are arranged at positions rotated by an angle θ clockwise with respect to the symmetry plane P.

  Next, the structure of the actuator 16 that drives the control shaft 15 will be described in detail with reference to FIGS. 1 to 4, 8, and 9.

  As apparent from FIGS. 2 and 3, the upper surface of the cylinder head 11 is inclined with respect to a horizontal plane, and the actuator housing 18 is fixed by four bolts 17A, 17A; 17B, 17B along the inclined direction. The

  As apparent from FIGS. 8 and 9, the actuator housing 18 is basically a cylindrical member, and bosses 18a to 18d through which the four bolts 17A, 17A; And an opening 18e into which the lower part of the worm wheel 23 is fitted is formed on the upper surface. One side edge 18f of the opening 18e is formed in a straight line, and the other side edge 18g is formed in a V shape.

  As is apparent from FIGS. 1 and 3, an elongated plate-like second stopper member 43 is fastened together with the two bolts 17 </ b> B and 17 </ b> B on the upper surface of the other side edge 18 g of the actuator housing 18. Two stopper surfaces 43a and 43b project from the upper surface of the second stopper member 43 sandwiched between the two bolts 17B and 17B, and one stopper surface 43a is one stopper surface 42a of the first stopper member 42. The other stopper surface 43b can contact the other stopper surface 42b of the first stopper member 42.

  As is apparent from FIG. 2, a step 18h having an enlarged inner diameter is formed on the inner peripheral surface of the higher end of the actuator housing 18, and the outer race 24a of the first ball bearing 24 is formed on the step 18h. The coupling cylinder part 21a of the casing of the electric motor 21 is fitted. An inner peripheral surface of the lower end portion of the actuator housing 18 is formed with a stepped portion 18i and a female threaded portion 18j having an enlarged inner diameter, and an outer race 25a of the second ball bearing 25 fitted to the stepped portion 18i is It is fixed by a lock nut 26 that is screwed into the female screw portion 18j.

  The worm shaft 27 disposed inside the actuator housing 18 has a first journal 27a at one end thereof supported on the outer race 24a of the first ball bearing 24 via a plurality of balls 24b. It is press-fitted into the inner race 24c. The second journal 27b on the other end side of the worm shaft 27 is fitted to an inner race 25c supported by the outer race 25a of the second ball bearing 25 via a plurality of balls 25b to be relatively rotatable, It is fixed with a lock nut 28.

  The motor output shaft 29 extending into the coupling cylindrical shape 21a of the casing of the electric motor 21 has an uneven engagement portion 29a whose tip portion has six crests and troughs alternately in the circumferential direction. The concavo-convex engaging portion 29a engages with the concavo-convex engaging portion 27c having six crests and troughs alternately formed in the inner circumference of the first journal 27a of the worm shaft 27 in the circumferential direction. (See FIG. 5). The concave / convex engaging portion 29a of the motor output shaft 29 of the electric motor 21 constituting the coupling 30 and the concave / convex engaging portion 27c of the worm shaft 27 are engaged in a spline shape to transmit rotation. A slight gap is formed so that rotation is transmitted while absorbing a radial shift between the axis of the motor output shaft 29 and the axis of the worm shaft 27.

  A large diameter portion 27d is formed on the inner side in the axial direction of the first journal 27a of the worm shaft 27, and the inner peripheral surface of the actuator housing 18 is slightly spaced from the outer periphery of the large diameter portion 27d (see FIGS. 2, 4 and 4). (See FIG. 6). A crescent-shaped notch 18k (see FIGS. 2 and 6) through which oil can pass is formed on the inner peripheral surface of the actuator housing 18 facing the upper portion of the large-diameter portion 27d. Further, a large-diameter portion 27e is formed on the inner side in the axial direction of the second journal 27b of the worm shaft 27, and the inner peripheral surface of the actuator housing 18 has a slight gap β (see FIG. 2 and FIG. 2) on the outer periphery of the large-diameter portion 27e. 4).

  The worm wheel 23 provided at the shaft end of the control shaft 15 meshes with the worm 22 formed at the center of the worm shaft 27 through the opening 18 e of the actuator housing 18.

  As apparent from FIGS. 2 and 8, an oil supply groove 18m and a dust collection chamber 18n are opened on the lower surface of the actuator housing 18, and the oil supply groove 18m passes through an oil supply passage 11a formed in the cylinder head 11. Communicate with an oil pump (not shown). An oil jet 18o is formed at the end of the oil supply groove 18m away from the oil supply passage 11a. The oil jet 18o is formed in the actuator housing 18 and the outer race of the first ball bearing 24. Communicating with an annular oil sump 31 defined by 24a and balls 24b, and a large diameter portion 27d of the worm shaft 27. The notch 18k opens at the highest position in the upper part of the oil sump 31.

  As apparent from FIGS. 4 and 7, a projecting portion 18 p is formed along the inner surface of the actuator housing 18 from a straight side edge 18 f that defines the opening 18 e of the actuator housing 18. The protruding portion 18p faces the outer peripheral surface of the worm 22 and one side surface of the worm wheel 23 with a slight gap γ so as to face the meshing portion of the worm 22 and the worm wheel 23. In particular, since the bottom wall of the actuator housing 18 is formed in an arc-shaped cross section so as to follow the outer peripheral surface of the worm 22, the outer peripheral surface of the worm 22 is surrounded by the gap γ over a range of 180 ° or more. ing.

  An oil jet 18r directed to the upper part of the meshing portion of the worm 22 and the worm wheel 23 is formed at the upper end of the oil guide groove 18q that branches upward from the oil supply groove 18m of the actuator housing 18 facing the oil supply passage 11a of the cylinder head 11. It is formed. The protrusion 18p of the actuator housing 18 is set to have a larger width W2 in the axial direction than the width W1 in the axial direction of the meshing portions of the worm 22 and the worm wheel 23.

  A small-diameter throttle portion 18s is formed on the lowest side of the bottom wall of the actuator housing 18, and the throttle portion 18s communicates with the dust collection chamber 18n. A dust collection chamber 11b is formed on the upper surface of the cylinder head 11 so as to be integrated with the dust collection chamber 18n. A drain passage 11 c extending from the lower side wall of the dust collection chamber 11 b communicates with the internal space of the cylinder head 11 via the oil filter 32.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the motor output shaft 29 is rotated by driving the electric motor 21, the rotation is decelerated and transmitted from the worm 22 formed on the worm shaft 27 connected to the motor output shaft 29 via the coupling 30 to the worm wheel 23, As the control shaft 15 rotates and the variable valve mechanisms 14 operate, the valve lift and valve timing of the intake valves 13 change.

  At this time, the coupling 30 that connects the motor output shaft 29 of the electric motor 21 to the worm shaft 27 is arranged on the inner circumference of the cylindrical first journal 27 a formed integrally with the worm shaft 27, and the outer circumference of the motor output shaft 29 is arranged on the inner circumference. The concave and convex engaging portions 27c and 29a are configured so as to be relatively non-rotatable, and the outer periphery of the cylindrical first journal 27a is rotatable to the inner periphery of the actuator housing 18 via the first ball bearing 24. Since it is supported, both the motor output shaft 29 and the worm shaft 27 can be simultaneously supported at the position of the coupling 30 by the single first ball bearing 24, and vibration and wear of the connecting portion are effectively suppressed. be able to.

  In addition, since the cylindrical first journal 27a is formed integrally with the worm shaft 27, not only can the number of parts of the coupling 30 be reduced and the size can be reduced, but also at least a part of the motor output shaft 29 is perpendicular to the axis. Thus, the first ball bearing 24 overlaps with the first ball bearing 24, so that the radial deflection of the motor output shaft 29 and the worm shaft 27 can be reliably suppressed by the single first ball bearing 24.

  The oil supplied from an oil pump (not shown) to the oil supply groove 18m on the lower surface of the actuator housing 18 via the oil supply passage 11a of the cylinder head 11 passes through the oil jet 18o connected to the oil supply groove 18m. The first ball bearing 24 facing the oil reservoir 31 is lubricated. The oil that has lubricated the first ball bearing 24 flows into the first oil storage chamber 33 and lubricates the coupling 30 disposed there, and the excess oil is a notch 18k formed in the upper portion of the actuator housing 18. It passes through the second oil storage chamber 34 (see FIGS. 2 and 6). Oil that has passed through the gap α on the outer periphery of the large-diameter portion 27 d of the worm shaft 27 also flows from the oil reservoir 31 into the second oil storage chamber 34 to lubricate the meshing portion between the worm 22 and the worm wheel 23.

  At this time, the worm 22 and the worm wheel 23 are engaged with each other inside the second oil storage chamber 34 formed in the actuator housing 18 that rotatably supports the worm shaft 27 via the first ball bearing 24, and the second oil storage. Since the oil jet 18o for indirectly supplying the oil to the chamber 34 is opened at the mounting portion of the first ball bearing 24 of the actuator housing 18, a part of the first ball bearing 24 has an oil level L (see FIG. 2), the first ball bearing 24 can be reliably lubricated, and the first ball bearing 24 can be supplied with clean oil with less contamination of wear powder to increase durability. be able to.

  Moreover, an annular oil reservoir 31 surrounding the outer periphery of the worm shaft 27 is defined by the worm shaft 27, the first ball bearing 24, and the actuator housing 18, and an oil jet 18 o is opened at the lower portion of the oil reservoir 31 and the oil reservoir 31. Since the notch 18k is formed in the portion facing the upper portion of the oil, the oil supplied from the oil jet 18o is held in the oil reservoir 31 and the first ball bearing 24 is reliably lubricated, and then the excess oil is removed from the first oil. It can be supplied from the storage chamber 33 to the second oil storage chamber 34 through the notch 18k.

  In the second oil storage chamber 34, the oil flows from the first ball bearing 24 at the higher position to the second ball bearing 25 at the lower position. As is apparent from FIG. Since a narrow gap γ is formed around the meshing portion with the worm wheel 23 by the projection 18p of the actuator housing 18, the oil passing through the clearance is surely acted on the meshing portion to enhance the lubricating effect. it can. Moreover, the oil supplied to the oil supply groove 18m on the lower surface of the actuator housing 18 is ejected from the oil guide groove 18q to the upper portion of the meshing portion between the worm 22 and the worm wheel 23 through the oil jet 18r. The lubrication effect of the meshing portion can be further enhanced.

  In particular, the opening of the oil jet 18r is formed at a position overlapping the worm 22 when viewed from above (see FIG. 7), and the meshing portion of the worm 22 and the worm wheel 23 is formed in the protruding portion 18p facing the outer periphery of the worm 22. Since it is provided within the axial width of the peripheral surface (see FIG. 4), the oil discharged from the oil jet 18r flows down by gravity and is held between the protrusion 18p of the actuator housing 18 facing the outer periphery of the worm 22. In addition, the lubrication effect can be enhanced by sufficiently applying oil to the meshing portions of the worm 22 and the worm wheel 23.

  A part of the oil that has lubricated the meshing portion of the worm 22 and the worm wheel 23 passes through the gap β on the outer periphery of the large-diameter portion 27e of the worm shaft 27 and lubricates the second ball bearing 25, and then the cylinder head 11 It is returned to the oil pan (not shown) by gravity from the top surface. Further, another part of the oil that has lubricated the meshing portion flows into the dust collection chambers 18n and 11b from the throttle portion 18s provided at the lowest position of the second oil storage chamber 34, and enters the dust collection chambers 18n and 11b. Foreign matter such as wear powder contained in the oil is collected. When the oil in the dust collection chambers 18n and 11b passes through the oil filter 32 provided in the drain passage 11c and is discharged, the wear powder contained in the oil is filtered by the filter 32. The filtered oil flowing out from the oil filter 32 is returned from the upper surface of the cylinder head 11 to the oil pan.

  As described above, since the dust collected in the oil is collected in the dust collection chambers 18n and 11b, the wear of the worm 22 and the worm wheel 23 due to the biting of the wear powder is suppressed, and its durability is improved. Can do. At this time, since the throttle portion 18s is provided between the second oil storage chamber 34 and the dust collection chambers 18n and 11b, the flow rate of the oil is regulated by the throttle portion 18s, and a sufficient amount is stored in the second oil storage chamber 34. Oil can be stored, and the throttle portion 18s is formed with a smaller diameter than the cross-sectional area of the dust collection chambers 18n and 11b, so that the wear powder once trapped in the dust collection chambers 18n and 11b is reduced in the throttle portion 18s. And the second oil storage chamber 34 is not returned.

  Further, since the amount of oil discharged from the dust collection chambers 18n and 11b through the drain passage 11c is set smaller than the amount of oil finally supplied from the oil jets 18o and 18r to the second oil storage chamber 34, the second A sufficient amount of oil is always stored in the oil storage chamber 34 so that the meshing portions of the worm 22 and the worm hole 23 can be reliably lubricated.

  Now, the pivotable range of the control shaft 15 is regulated by the minimum and maximum sides of the valve lift, and the valve lift becomes too small and it becomes difficult to start the internal combustion engine, or the valve lift becomes too large. Thus, the intake valves 13, 13 are prevented from interfering with the piston. Normally, the controllable range of the control shaft 15 is controlled by the control of the electric motor 21, but in the unlikely event that the control system of the electric motor 21 fails, the control shaft can be controlled by mechanical stopper means. The range of 15 possible rotations is restricted.

  FIG. 3 shows a state in which the control shaft 15 and the worm wheel 23 are forcibly stopped by a mechanical stopper at a clockwise limit rotational position (minimum valve lift position). That is, the one stopper surface 42a of the first stopper member 42 integral with the control shaft 15 is brought into contact with the one stopper surface 43a of the second stopper member 43 fixed to the upper surface of the actuator housing 18 at a point a. Further rotation of the shaft 15 in the clockwise direction is restricted, and the minimum valve lift necessary for starting is ensured.

  Conversely, when the control shaft 15 and the worm wheel 23 are in the counterclockwise limit rotational position (maximum valve lift position), the other stopper surface 42b of the first stopper member 42 is in contact with the other stopper surface 43a of the second stopper member 43. By abutting at the point b, further rotation of the control shaft 15 in the counterclockwise direction is restricted, and interference between the intake valves 13 and the piston is avoided.

  As apparent from FIG. 3, when the stopper surfaces 42a and 42b of the first stopper member 42 come into contact with the stopper surfaces 43a and 43b of the second stopper member 43 at the minimum valve lift position or the maximum valve lift position, the first stopper member 42, the stopper surfaces 42a and 42b are parallel to the upper surfaces of the second stopper member 43, the actuator housing 18 and the cylinder head 11, that is, the bolts 17B and 17B for fastening the second stopper member 43 and the actuator housing 18 to the cylinder head 11. Therefore, the load due to the torque of the control shaft 15 is efficiently transmitted from the second stopper member 43 to the cylinder head 11 via the actuator housing 18, and the second stopper member 43 and the actuator housing 18 are thus transmitted. Specially Without applying the reinforcement, the minimum valve lift position or the maximum valve lift position of the control shaft 15 to enhance the fastening rigidity of the second stopper member 43 can be accurately regulated.

  Moreover, the second stopper member 43 is fastened together by two bolts 17B, 17B among the four bolts 17A, 17A; 17B, 17B that fasten the actuator housing 18 to the cylinder head 11, so that the number of bolts is reduced. In addition to the reduction, the second stopper member 43 is fastened to the actuator housing 18 with a bolt, and the fastening rigidity of the second stopper member 43 is increased as compared with the case where the actuator housing 18 is fastened to the cylinder head 11 with another bolt. be able to. In addition, since the second stopper member 43 is fastened to the cylinder head 11 using the actuator housing 18, a special member that supports the second stopper member 43 is not required, and the number of parts can be reduced. The second stopper member 43 can be firmly fastened using the highly rigid actuator housing 18.

  Further, since the actuator housing 18 and the second stopper member 43 are provided closer to the cylinder head 11 than the control shaft 15 and the first stopper member 42 is integrally formed on the end face in the axial direction of the worm wheel 23, the first stopper member 42 and the worm Not only can the number of components be reduced by integrating the wheel 23, but also the axial dimension of the stopper means can be reduced.

  As is apparent from FIG. 3, the three bolts 41A, 41B, 41C for fastening the first stopper member 42 to the flange 15a of the control shaft 15 are provided between the control shaft 15 and the second stopper member 43 during the minimum valve lift. The number (the two bolts 41B and 41C shown by the solid line) existing between them is one of the numbers (the bolt 41A shown by the chain line) existing between the control shaft 15 and the second stopper member 43 during the maximum valve lift. Even if the first stopper member 42 repeatedly receives the reaction force of the contact load from the second stopper member 43 at the time of the minimum valve lift, the frequency of occurrence is much higher than that at the time of the maximum valve lift. A large number of bolts are arranged at positions close to the contact portions of the second stopper members 42 and 43, so that the control shaft It is possible to sufficiently secure the fastening rigidity of the first stopper member 42 for 15.

  Further, a worm 22 and a worm wheel 23 for transmitting the driving force of the electric motor 21 to the control shaft 15 on one shaft end side of the control shaft 15 that is rotated by the electric motor 21 to operate the variable valve mechanism 14, and the control shaft Since the first and second stopper members 42 and 43 for restricting the 15 rotatable ranges are provided, the worm 22 and the worm wheel 23 and the first and second stopper members 42 and 43 are brought as close as possible. Thus, twisting of the control shaft 15 can be suppressed, and excessive rotation of the control shaft 15 can be minimized.

  In addition, since the first stopper member 42 is integrally formed on the end surface in the axial direction of the worm wheel 23, not only the number of parts can be reduced, but also the rigidity of the worm wheel 23 and the first stopper member 42 can be enhanced.

  Further, since the rotation angle sensor 20 is provided at one shaft end of the control shaft 15 and the first stopper member 42 is disposed between the worm wheel 23 and the rotation angle sensor 20, the first stopper member 42 of the control shaft 15 is arranged. A portion twisted by a load applied to the first stopper member 42 and the worm wheel 23 is suppressed between the first stopper member 42 and the worm wheel 23, and no twist is generated between the first stopper member 42 and the rotation angle sensor 20. The detection accuracy of the rotational angle position of the control shaft 15 can be ensured to the maximum.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the position of the actuator 16 of the first embodiment is moved from one end side of the control shaft 15 to the other end side. Also according to the second embodiment, it is possible to achieve the same effect as that of the first embodiment.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the driving force transmission means includes the worm 22 and the worm wheel 23, but the driving force transmission means is not limited thereto.

  In the embodiment, the first stopper member 42 is fastened to the cylinder head 11 via the actuator housing 18, but can be fastened to the cylinder head 11 via parts other than the actuator housing 18.

The top view of the cylinder head of the multicylinder engine provided with the variable valve mechanism based on 1st Embodiment 2-2 line enlarged sectional view of FIG. 3-3 enlarged sectional view of FIG. Sectional view along line 4-4 in FIG. Sectional view along line 5-5 in FIG. Sectional view along line 6-6 in FIG. Sectional view along line 7-7 in FIG. 8-8 arrow view of FIG. 9 direction arrow view of FIG. The figure corresponding to the said FIG. 1 based on 2nd Embodiment.

Explanation of symbols

14 Variable valve mechanism 15 Control shaft 18 Actuator housing 20 Rotation angle sensor (sensor)
21 Electric motor 22 Worm (driving force transmission means)
23 Worm wheel (drive force transmission means)
42 First stopper member (stopper means)
43 Second stopper member (stopper means)

Claims (5)

In a variable valve mechanism actuator for operating at least a valve lift of an internal combustion engine by operating a variable valve mechanism (14) with a control shaft (15) connected to an electric motor (21) and rotating,
Driving force transmitting means (22, 23) for transmitting the driving force of the electric motor (21) to the control shaft (15) on one shaft end side of the control shaft (15), and the control shaft (15) An actuator for a variable valve mechanism, characterized in that it is provided with stopper means (42, 43) for restricting the pivotable range of the valve mechanism.   The driving force transmission means includes a worm (22) rotated by the electric motor (21), and a worm wheel (23) provided on the control shaft (15) and meshing with the worm (22), The stopper means includes a first stopper member (42) provided on the worm wheel (23), and a second stopper member (43) with which the first stopper member (42) can come into contact. The actuator for a variable valve mechanism according to claim 1.   The actuator for a variable valve mechanism according to claim 2, wherein the first stopper member (42) is integrally formed on an axial end surface of the worm wheel (23).   A sensor (20) for detecting the rotational position of the control shaft (15) is provided at one shaft end of the control shaft (15), and the first stopper member (42) includes the worm wheel (23) and the sensor. The actuator for a variable valve mechanism according to claim 2 or 3, wherein the actuator is disposed between (20) and (20).   An actuator housing (18) for housing the worm (22) is disposed below the control shaft (18), and the actuator housing (18) is provided with the second stopper member (43). The actuator for a variable valve mechanism according to any one of claims 2 to 4.

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