JP2009180207A - Actuator for variable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the durability by effectively lubricating a bearing for supporting a worm shaft in an actuator housing in an actuator for a variable valve mechanism. <P>SOLUTION: A worm 22 and worm wheel 23 are meshed with each other in an oil storage chamber 34 formed in an actuator housing 18 for freely rotatably supporting a worm shaft 27 through the medium of a ball bearing 24. An oil jet 18o for supplying oil to the oil storage chamber 34 is opened to a mounting part of the ball bearing 24. By so doing, even when the ball bearing 24 is arranged in a position higher than an oil level of the actuator housing 18, the actuator can not only surely perform lubrication, but also supply clean oil containing less wear powder to the ball bearing 24, thereby enhancing the durability. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention connects a worm shaft to a motor output shaft of an electric motor, meshes a worm wheel with the worm provided on the worm shaft, and decelerates the rotation of the motor output shaft with the worm and the worm wheel to make a variable motion. The present invention relates to an actuator for a variable valve mechanism that changes at least one of a valve lift and a valve timing of an internal combustion engine by operating a valve mechanism.

A screw shaft and a ball screw mechanism for operating a variable valve mechanism of an internal combustion engine with an electric motor are housed in a housing, and an oil is supplied to the housing to support the screw shaft and mesh with a ball screw mechanism. It is known from Patent Document 1 below that the part is lubricated.
JP 2006-144551 A

  By the way, in the above conventional one, the housing is inclined so that the electric motor side becomes higher, and both ends of the screw shaft are supported by the housing via bearings. There was a problem that the lubricating oil did not spread over the bearings supporting the ends and the life of the bearings was shortened.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to effectively lubricate a bearing that supports a worm shaft in an actuator housing of an actuator for a variable valve mechanism to enhance durability.

  To achieve the above object, according to the first aspect of the present invention, a worm shaft is connected to a motor output shaft of an electric motor, a worm wheel is meshed with a worm provided on the worm shaft, and the motor output An actuator for a variable valve mechanism that changes at least one of a valve lift and a valve timing of an internal combustion engine by operating a variable valve mechanism by decelerating the rotation of a shaft with the worm and the worm wheel. An oil supply hole for meshing the worm and the worm wheel inside an oil storage chamber formed in an actuator housing that rotatably supports a shaft via a bearing, and supplying oil to the oil storage chamber is provided in the actuator housing. A variable valve characterized by opening to the bearing mounting構用 actuator is proposed.

  According to the invention described in claim 2, in addition to the configuration of claim 1, an annular oil sump surrounding the outer periphery of the worm shaft is defined by the worm shaft, the bearing, and the housing. The oil supply hole is opened at a lower portion of the oil reservoir, and an oil passage for supplying the oil in the oil reservoir to the oil storage chamber is formed in a portion of the actuator housing facing the upper portion of the oil reservoir. An actuator for a variable valve mechanism is proposed.

  The notch 18k of the embodiment corresponds to the oil passage of the present invention, the oil jet 18o of the embodiment corresponds to the oil supply hole of the present invention, and the first ball bearing 24 of the embodiment corresponds to the oil passage of the present invention. Corresponding to the bearing, the second oil storage chamber 34 of the embodiment corresponds to the oil storage chamber of the present invention.

  According to the first aspect of the present invention, the oil is supplied to the oil storage chamber by engaging the worm and the worm wheel inside the oil storage chamber formed in the actuator housing that rotatably supports the worm shaft via the bearing. Since the supply hole is opened to the bearing mounting part of the actuator housing, it is possible not only to lubricate even if the bearing is positioned higher than the oil level of the actuator housing, but also to introduce wear powder into the bearing. The durability can be improved by supplying a small amount of clean oil.

  According to the second aspect of the present invention, the annular oil reservoir surrounding the outer periphery of the worm shaft is partitioned by the worm shaft, the bearing and the housing, the oil supply hole is opened at the lower portion of the oil reservoir, and at the upper portion of the oil reservoir. Since the oil passage is formed in the opposing portion, the oil supplied from the oil supply port can be held in the oil sump and the bearing can be reliably lubricated.

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

  1 to 8 show an 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 an enlarged sectional view taken along line 2-2 of FIG. 3 is a 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. 7 is a sectional view taken along the line 7-7 in FIG. 2, and FIG. 8 is a view taken in the direction of arrow 8 in 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 17..., And one end of the control shaft 15 is rotatable on a bearing 19 provided near the actuator housing 18. Supported. A resolver 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 a 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 provided on a motor output shaft 29 of the electric motor 21 is connected to the control shaft. The control shaft 15 is rotationally driven by the driving force of the electric motor 21 by meshing with the worm wheel 23 provided on the motor 15.

  Next, the structure of the actuator 16 that drives the control shaft 15 will be described in detail with reference to FIGS. 2, 3, 7, and 8.

  As is apparent from FIG. 2, the upper surface of the cylinder head 11 is inclined with respect to the horizontal plane, and the actuator housing 18 is fixed by four bolts 17 along the inclined direction. The actuator housing 18 is basically a cylindrical member, and is formed with boss portions 18a to 18d through which the four bolts 17... Penetrate, and a lower portion of the worm wheel 23 is fitted to the upper surface thereof. An opening 18e is formed. 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.

  A step portion 18 h having an enlarged inner diameter is formed on the inner peripheral surface of the higher end portion of the actuator housing 18, and a coupling cylinder of the outer race 24 a of the first ball bearing 24 and the casing of the electric motor 21 is formed on the step portion 18 h. The part 21a 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. 4). 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 of the worm shaft 27 in the axial direction of the first journal 27a, and the inner peripheral surface of the actuator housing 18 has a slight gap α (see FIGS. 2, 3, and 3) on the outer periphery of the large-diameter portion 27d. (See FIG. 5). A crescent-shaped notch 18k (see FIGS. 2 and 5) 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. 3).

  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 7, an oil supply groove 18 m and a dust collection chamber 18 n are opened on the lower surface of the actuator housing 18, and the oil supply groove 18 m passes through an oil supply passage 11 a 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.

  As apparent from FIGS. 3 and 6, a protruding 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 5). 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. 3), not only can the first ball bearing 24 be reliably lubricated, but also the first ball bearing 24 is supplied with clean oil with less 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 with the worm 22 when viewed from above (see FIG. 6), 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. 3), 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.

  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, the bearing of the present invention is not limited to the ball bearing 24 of the embodiment, and may be an arbitrary bearing such as a roller bearing, a needle bearing, or a plain bearing.

Plan view of cylinder head of multi-cylinder engine equipped with variable valve mechanism 2-2 line enlarged sectional view of FIG. 3-3 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. FIG. 7-7 arrow view of FIG. 8 direction arrow view of FIG.

Explanation of symbols

14 Variable valve mechanism 18 Actuator housing 18k Notch (oil passage)
18o Oil jet (oil supply hole)
21 electric motor 22 worm 23 worm wheel 24 first ball bearing (bearing)
27 Warm shaft 29 Motor output shaft 31 Oil reservoir 34 Second oil reservoir (oil reservoir)

Claims (2)

  The worm shaft (27) is connected to the motor output shaft (29) of the electric motor (21), the worm wheel (23) is engaged with the worm (22) provided on the worm shaft (27), and the motor output shaft ( 27) A variable motion that changes at least one of the valve lift and the valve timing of the internal combustion engine by operating the variable valve mechanism (14) by decelerating the rotation of the worm (22) and the worm wheel (23). An actuator for a valve mechanism, wherein the worm (22) and the worm shaft (27) are formed inside an oil storage chamber (34) formed in an actuator housing (18) that rotatably supports the worm shaft (27) via a bearing (24). An oil supply hole (18o) for meshing the worm wheel (23) and supplying oil to the oil storage chamber (34) The variable valve mechanism actuator, characterized in that the opening in the mounting portion of the bearing (24) of said actuator housing (18).   The worm shaft (27), the bearing (24), and the housing (18) define an annular oil reservoir (31) that surrounds the outer periphery of the worm shaft (27), and the oil reservoir (31) The oil supply hole (18o) is opened in the lower portion, and the oil in the oil reservoir (31) is supplied to the oil reservoir (34) in a portion of the actuator housing (18) facing the upper portion of the oil reservoir (31). The actuator for a variable valve mechanism according to claim 1, wherein an oil passage (18k) is formed.

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