JP2007285308A - Variable valve gear of internal combustion engine and drive mechanism used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change the speed reduction ratio of a speed reduction means in response to a valve lift quantity of an engine valve. <P>SOLUTION: The device is equipped with a variable mechanism 4 for controlling the increase and decrease of lift quantity of intake valves 2, 2 through the rotation of a control shaft 32 according to an engine operating state, and a drive mechanism 6 for controlling the rotation of the control shaft. A screw transmission means 37 of a speed reduction means of the drive mechanism consists of a screw shaft 45 rotated by an electric motor 36 and including a male screw part 49 in an outer peripheral surface, a screw nut 46 treadedly engaged with the male screw part and moving in an axial direction of an output shaft in response to the rotation of the screw shaft, and a link member 48 and connecting link 47 for connecting the screw nut and the control shaft. The speed reduction ratio of the screw transmission means is set to be minimum in a state where the valve lift quantity of an engine valve is controlled to be maximum and to be maximum in a state where the valve lift quantity of the engine valve is controlled to be minimum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve operating device for an internal combustion engine that can vary at least the operating angle of an intake valve and an exhaust valve, which are engine valves, according to an engine operating state.

  As this type of conventional variable valve gear, for example, there is one described in Patent Document 1 below.

  Briefly, this variable valve operating device is applied to the intake valve side, and the shaft center is eccentric from the shaft center of the drive shaft on the outer periphery of the drive shaft rotating in synchronization with the rotation of the crankshaft. A drive cam is provided, and the rotational force of the drive cam is transmitted via a multi-joint link-like transmission means, and the cam surface slides on the upper surface of the valve lifter at the upper end of the intake valve to control the intake valve. It has a swing cam that opens against the spring force of the valve spring.

  The transmission means includes a rocker arm that is disposed above the swing cam and is swingably supported by the control shaft, an annular one end is fitted to the outer peripheral surface of the drive cam, and the other end is one end of the rocker arm. A link arm that is rotatably connected to the part via a pin, one end part is rotatably connected to the other end part of the rocker arm via a pin, and the other end part is connected to the cam nose part of the swing cam via a pin. And a link rod connected rotatably.

  The control shaft is rotationally driven through, for example, an electric motor and a worm gear gear serving as a speed reduction unit provided on the drive shaft of the electric motor. A control cam that is eccentric by a predetermined amount from the shaft center is fixed. This control cam is rotatably fitted in and held in a support hole drilled in the approximate center of the rocker arm, and the rocking fulcrum of the rocker arm is changed in accordance with the rotational position, so that the valve on the cam surface of the rocking cam The valve lift amount and the operating angle of the intake valve are variably controlled by changing the rolling contact position with respect to the upper surface of the lifter.

  That is, when the engine operating state is, for example, in a low rotation range, the rocker arm swinging fulcrum is achieved by rotating the control shaft in one direction via the electric motor and the worm gear gear and rotating the control cam in the same direction. Move the position away from the drive shaft. As a result, the pivot point of the rocker arm and the link rod moves upward to raise the cam nose portion of the swing cam, whereby the contact position of the swing cam with respect to the upper surface of the valve lifter moves away from the lift portion. Therefore, the intake valve is controlled so that its valve lift and operating angle are minimized.

  On the other hand, when shifting from a low rotation range to a high rotation / high load range, the control shaft rotates in the other direction via the worm gear gear by the electric motor, and the control cam rotates in the same direction. Moves in a direction approaching the drive shaft. As a result, the end of the swing cam is pushed down by a link rod or the like, and the contact position of the upper surface of the valve lifter moves toward the lift portion. Therefore, the intake valve is controlled so that the valve lift amount and the operating angle increase. Is done.

Therefore, the engine performance can be sufficiently exhibited according to the engine operating state, that is, the fuel consumption and output can be improved.
Japanese Patent Laid-Open No. 2001-3720

  In the conventional variable valve operating device, the worm gear mechanism that controls the rotation of the control shaft by decelerating the rotational driving force from the electric motor has a reduction ratio as shown by the broken line in FIG. Regardless of the control state of either the amount or the operating angle, it is always constant. Therefore, in the small valve lift amount and the small operating angle control state, which are the control regions in the normal operation range (practical range) of the vehicle, Since the reduction ratio becomes small, the electric power consumption of the electric motor becomes large.

  That is, the speed reduction ratio is obtained from the angular speed of the drive shaft of the electric motor / the angular speed of the control shaft, and corresponds to the rotational torque ratio of the electric motor, which is proportional to the current supplied to the electric motor. Yes. Therefore, in the conventional small valve lift amount and small operating angle control state, the reduction ratio is not improved and the reduction ratio becomes relatively small, so that the rotational torque of the electric motor that rotates the control shaft becomes large.

  For this reason, the power consumption during steady operation of the vehicle increases, and as a result, the fuel consumption of the internal combustion engine that drives the auxiliary machines such as the alternator is also affected.

  In addition, if the power supplied to the electric motor is reduced, for example, because the amount of power stored in the battery that supplies power to the electric motor is reduced, the rotational operability of the electric motor in the normal range of the vehicle is deteriorated. There is also a risk that technical issues such as

  Furthermore, during a sudden acceleration of the vehicle, the reduction ratio is constant and does not decrease even during the conversion process from the small valve lift to the large valve lift of the intake valve by the variable mechanism. The total number of revolutions cannot be reduced. Therefore, this conversion time becomes long, and there is a possibility that the operation responsiveness from a so-called small valve lift to a large valve lift may be lowered.

  The present invention has been devised in view of the actual state of the conventional variable valve operating device. In the invention according to claim 1, in particular, the reduction ratio of the speed reduction means is set by the variable mechanism. The valve lift amount is the smallest in the state where it is controlled to be the largest, and the valve lift amount of the engine valve is the largest in the state where it is controlled to be the smallest.

  According to the first aspect of the invention, during the small valve lift amount and the small operating angle control of the internal combustion engine, which is a practical range of the vehicle, for example, in the low rotation range, the reduction ratio of the reduction means is large. The rotational torque of the motor is reduced, and the power consumption of the electric motor can be reduced as much as possible.

  On the other hand, when shifting from the low rotation range, which is a practical range, to a high rotation range due to sudden acceleration, etc., and converted into a large valve lift amount and a large operating angle, the reduction ratio during such switching becomes small, Although the rotational torque of the electric motor is increased and the power consumption is increased, the switching operation response at the time of switching is improved. As a result, the acceleration performance of the vehicle is improved.

  According to a second aspect of the present invention, the speed reducer is linked to the electric motor, and is screwed into the screwed portion with an output shaft having a screwed portion on the outer periphery, and the output A moving member that moves in the axial direction of the output shaft according to the rotation of the shaft, a link member that is swingably linked to the moving member, and a swingable link that is linked to the other end of the link member. And a linkage portion that rotates the control shaft by the driving force transmitted from the link member as the moving member moves in the axial direction, and the valve lift amount of the engine valve is controlled to the maximum by the variable mechanism. When the angle between the link member and the output shaft is the smallest, and when the valve lift amount of the engine valve is controlled to be the smallest by the variable mechanism, the angle between the link member and the output shaft is the largest. Specially formed It is set to.

  Therefore, according to the present invention, the angle formed between the link member and the output shaft is increased in the small valve lift state of the engine valve controlled within the practical range of the vehicle. The rotation angle of the linkage portion linked to the other end portion of the link member, that is, the rotation angle of the control shaft is reduced with respect to the ratio of the actual rotation speed. That is, the so-called reduction ratio is increased, and as a result, the rotational torque of the electric motor is reduced and the power consumption can be reduced.

  On the other hand, when the small valve lift state is switched to the large valve lift state, the angle formed between the link member and the output shaft is reduced, so the so-called reduction ratio is reduced and the actual rotational speed of the output shaft is reduced. The rotation angle of the control shaft with respect to the ratio increases. For this reason, although the rotational torque of the electric motor increases, the rotational response of the linkage portion, that is, the response to switching to the large valve lift by the control shaft is improved. As a result, the acceleration performance of the vehicle is improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a variable valve operating apparatus according to the present invention and a drive mechanism used therefor will be described in detail with reference to the drawings.

  In this embodiment, the variable valve operating device is applied to the intake valve side, and is provided with two intake valves per cylinder, and the valve lift and operating angle of the intake valves are varied according to the engine operating state. It has become.

  That is, the variable valve operating apparatus in the first embodiment is slidably provided on the cylinder head 1 via a valve guide (not shown) as shown in FIGS. A pair of intake valves 2 and 2 urged to each other, a variable mechanism 4 that variably controls the valve lift amount of each intake valve 2, 2, a control mechanism 5 that controls the operating position of the variable mechanism 4, And a drive mechanism 6 that rotationally drives the control mechanism 5.

  The variable mechanism 4 includes a hollow drive shaft 13 rotatably supported by a bearing 14 above the cylinder head 1, a drive cam 15 that is an eccentric rotary cam fixed to the drive shaft 13 by press fitting, and the like. The two which are supported by the outer peripheral surface of the drive shaft 13 so that rocking is possible, and are slidably contacted with the valve lifters 16 and 16 provided at the upper ends of the intake valves 2 and 2 to open the intake valves 2 and 2. Oscillating cams 17 and 17, and a transmission means linked between the drive cam 15 and the oscillating cams 17 and 17 for transmitting the rotational force of the drive cam 15 as the oscillating force of the oscillating cams 17 and 17. ing.

  As shown in FIG. 2, the drive shaft 13 is arranged along the longitudinal direction of the engine, and a driven sprocket (not shown) provided at one end, a timing chain wound around the driven sprocket, and the like. Rotational force is transmitted from the crankshaft of the engine via this, and this rotational direction is set in the clockwise direction (arrow direction) in FIG.

  As shown in FIG. 3A, the bearing 14 is provided at the upper end portion of the cylinder head 1 to support the upper portion of the drive shaft 13, and the control shaft, which will be described later, is provided at the upper end portion of the main bracket 14a. The brackets 14a and 14b are fixed together from above by a pair of bolts 14c and 14c.

  The drive cam 15 has a substantially ring shape, and includes an annular cam main body and a cylindrical portion integrally provided on the outer end surface of the cam main body, and a drive shaft insertion hole is formed through the inner shaft. In addition, the axis Y of the cam body is offset from the axis X of the drive shaft 13 in the radial direction by a predetermined amount β. The drive cam 15 is press-fitted and fixed to the drive shaft 13 through one of the drive shaft insertion holes on the outer side that does not interfere with the valve lifters 16 and 16, and the outer peripheral surface of the cam body is an eccentric circle. The cam profile is formed.

  The valve lifters 16 and 16 are formed in a cylindrical shape with a lid, are slidably held in the holding holes of the cylinder head 1, and have a flat upper surface on which the swing cams 17 and 17 are in sliding contact. Yes.

  As shown in FIGS. 2 and 3, both the swing cams 17 have substantially the same raindrop shape, and are integrally provided at both ends of the annular camshaft 20. Is rotatably supported by the drive shaft 13 via the inner peripheral surface. In addition, a pin hole is formed through one end of the cam nose portion 21 side, and a cam surface 22 is formed on the lower surface. The base circle surface on the camshaft 20 side and the cam nose portion 21 side from the base circle surface. A ramp surface extending in an arc shape, and a lift surface connected to the top surface of the maximum lift from the ramp surface to the tip side of the cam nose portion 21, and the base circle surface, the ramp surface, and the lift surface are swung. Depending on the swing position of the cam 17, the valve lifter 16 comes into contact with a predetermined position on the upper surface.

  As shown in FIGS. 2 to 5, the transmission means includes a rocker arm 23 disposed above the drive shaft 13, a link arm 24 linking the one end portion 23 a of the rocker arm 23 and the drive cam 15, and the rocker arm 23. The other end portion 23b of the first and second rocking cams 17 are linked to each other.

  The rocker arm 23 is rotatably supported by a control cam 33 (to be described later) through a support hole at a cylindrical base portion at the center. Further, the one end portion 23a projecting from the outer end portion of the cylindrical base portion is formed with a pin hole through which the pin 26 is inserted, while the other end projecting from the inner end portion of the base portion. The part 23b is formed with a pin hole into which the pin 27 connected to the one end part 25a of the link rod 25 is fitted.

  The link arm 24 includes an annular base 24a having a relatively large diameter and a projecting end 24b projecting at a predetermined position on the outer peripheral surface of the base 24a. The drive cam 15 is located at the center of the base 24a. A fitting hole 24c is formed in which the cam body is rotatably fitted, and a pin hole through which the pin 26 is rotatably inserted is formed in the protruding end 24b.

  The link rod 25 is formed in a substantially square shape having a concave shape on the rocker arm 23 side, and is inserted into each pin hole of the other end portion 23b of the rocker arm 23 and the cam nose portion 21 of the swing cam 17 at both end portions 25a and 25b. Pin insertion holes through which end portions of the pins 27 and 28 are rotatably inserted are formed.

  A snap ring that restricts the movement of the link arm 24 and the link rod 25 in the axial direction is provided at one end of each pin 26, 27, 28.

  The control mechanism 5 is rotatably mounted on the same bearing 14 at a position above the drive shaft 13, and is fixed to the outer periphery of the control shaft 32 and is slidably fitted into a support hole of the rocker arm 23. And a control cam 33 serving as a rocking fulcrum of the rocker arm 23.

  As shown in FIG. 2, the control shaft 32 is arranged in the longitudinal direction of the engine in parallel with the drive shaft 13, and a journal portion 32b at a predetermined position is formed between the main bracket 14a and the sub bracket 14b of the bearing 14. The bearing is rotatably supported between them.

  The control cam 33 has a cylindrical shape as shown in FIGS. 2 to 5, and the position of the shaft center P <b> 2 is deviated from the shaft center P <b> 1 of the control shaft 32 by α by the thick portion.

  As shown in FIGS. 1, 2, 6, and 7, the drive mechanism 6 includes a housing 35 fixed to the rear end portion of the cylinder head 1 and a rotational force applied to one end portion of the housing 35. An electric motor 36 that is a mechanism, and a screw transmission means 37 that is a reduction means that is provided inside the housing 35 and transmits the rotational driving force of the electric motor 36 to the control shaft 32 at a reduced speed.

  The housing 35 protrudes upward in the center of the upper end portion of the cylindrical portion 35a disposed along the direction perpendicular to the axis of the control shaft 32, and the one end portion 32a of the control shaft 32 is provided therein. The bulging part 35b which faces, and the side wall 35c which obstruct | occludes one side part of the cylindrical part 35a and the bulging part 35b are comprised.

  The electric motor 36 is constituted by a proportional type DC motor, and a small diameter end portion 38a of a substantially cylindrical motor casing 38 is fixed to one end opening portion 35c of the cylindrical portion 35a by press fitting or the like. The drive shaft 36a of the electric motor 36 is supported by a ball bearing 39 provided in the small diameter portion 38a at the tip of the motor casing 38.

  The electric motor 36 is driven by a control signal from the controller 40 that detects the operating state of the engine. The controller 40 includes a crank angle sensor 41 for detecting the engine speed, an air flow meter 42 for detecting the intake air amount, a water temperature sensor 43 for the engine, a potentiometer 44 for detecting the rotational position of the control shaft 32, and the like. The electric motor 36 is feedback-controlled by detecting the current engine operating state by calculation or the like by inputting detection signals from the sensors.

  1, 6, and 7, the screw transmission means 37 is a screw shaft that is an output shaft disposed substantially coaxially with the drive shaft 36 a of the electric motor 36 in the cylindrical portion 35 a of the housing 35. 45, a screw nut 46 that is a moving member screwed to the outer periphery of the screw shaft 45, a linkage arm 47 that is a linkage portion fixed to the outer circumference of one end of the control shaft 32 in the housing 35, and the linkage It is mainly composed of a link member 48 that links the arm 47 and the screw nut 46.

  The screw shaft 45 is continuously formed with a male thread portion 49 as a threaded portion on the entire outer peripheral surface excluding both ends, and faces the one end opening portion 35c and the other end opening portion 35d of the cylindrical portion 35a. Both end portions 45 a and 45 b are rotatably supported by ball bearings 50 and 51.

  A nut 52 that holds the screw shaft 45 in the cylindrical portion 35a is screwed to the tip of the other end portion 45b of the screw shaft 45. The nut 52 has a protruding portion 52a on one end side on one side. The inner ring 51a of the ball bearing 51 is pressed against and fixed to a step portion on the other end portion 45b side of the screw shaft 45, and rotates integrally with the screw shaft 45. The other end opening 35d of the cylindrical portion 35a is screwed with a hook-shaped cap 53, and the cylindrical front end portion of the cap 53 connects the outer ring 51b of the one-side ball bearing 51 to the other end opening portion 35d. The step portion 35f is pressed and fixed.

  Note that the other end portion 45b of the screw shaft 45 has a two-surface width that engages the holding jig so that the screw shaft 45 does not rotate when the nut 52 is tightened with a predetermined jig such as a spanner. Interfacing surfaces 45d and 45d are formed.

  Further, in the screw shaft 45, the tip small-diameter shaft 45c of the one end portion 45a and the tip small-diameter portion 36b of the drive shaft 36a of the electric motor 36 are serration-coupled by a cylindrical connecting member 54 so as to be axially movable.

  That is, serration irregularities are formed along the axial direction on the outer peripheral surfaces of the tip small diameter shaft 45c and the tip small diameter portion 36b, while the serration irregularities are fitted on the inner peripheral surface of the connecting member 54 in a loosely fitted state. A mating serration portion is formed along the axial direction, and the rotational driving force of the electric motor 36 is transmitted to the screw shaft 45 by the serration coupling, and a slight movement of the screw shaft 45 in the axial direction is allowed.

  The screw nut 46 is formed in a substantially cylindrical shape, and is formed with a female screw portion 55 that is screwed into the male screw portion 49 and converts the rotational force of the screw shaft 45 into a moving force in the axial direction on the entire inner peripheral surface. In addition, as shown in FIG. 7, pin holes 56, 56 are formed along the diametrical direction at both ends of the substantially central position in the axial direction.

  As shown in FIGS. 1 and 2, the linkage arm 47 is formed in a substantially raindrop shape, and one end portion 32a of the control shaft 32 is inserted into a fixing hole 47a penetratingly formed in the large diameter base portion. The slit 57 is formed at the center in the width direction of the tapered tip 47b, and is fixed to the one end 32a by a bolt (not shown). Two pin holes 47c and 47c are formed so as to continuously pass along. Therefore, the axis Z of the pin holes 47c and 47 is offset from the axis P1 of the control shaft 32.

  The link member 48 is formed in a substantially Y shape and includes a flat plate-like one end portion 58 and bifurcated other end portions 59 and 59, and the one end portion 58 is inserted into the slit 57 of the linkage arm 47. The pin holes 47c, 47c and the pin 60 penetrating through the pin holes 58a are rotatably connected to the distal end portion 47b of the linkage arm 47. On the other hand, the bifurcated other end portions 59, 59 are arranged on both sides of the screw nut 46 and are respectively inserted into pin holes 59 a, 59 a that are formed so as to penetrate each other and pin holes 56, 56 of the screw nut 46. Two pin shafts 61 and 61 are rotatably connected to the screw nut 46. Note that both ends of the pin 60 are fixed to both pin holes 47 c and 47 c of the linkage arm 47, and the center part is slidable into the pin hole 58 a of the link member 48. On the other hand, the outer ends of the pin shafts 61 and 61 are press-fitted and fixed in the pin holes 59a and 59a of the link members 48, and the inner ends are slidable in the pin holes 56 and 56 of the screw nut 46. It has become.

  Further, inside the side wall 35e of the housing 35, as shown in FIG. 1 and FIG. 6, there are two first restriction mechanisms that restrict the left and right maximum rotational positions of the control shaft 32 via the linkage arm 47. Second stopper pins 62 and 63 are provided.

  That is, the first stopper pin 62 is fixed to the side wall 35e position where the control shaft 32 rotates counterclockwise in FIG. 1 and the variable mechanism 4 makes the valve lift amount of the intake valves 2 and 2 the minimum lift. ing. On the other hand, the second stopper pin 63 is fixed at the side wall 35e position where the control shaft 32 rotates clockwise as shown in the drawing and the valve lift amount is the maximum lift. , 63 regulates the counterclockwise and clockwise maximum rotational positions around the control shaft 32.

  Then, as shown in FIG. 6, the control shaft 32 is at a position where the rotation is restricted by the first stopper pin 62 via the linkage arm 47, that is, the variable mechanism 4 is connected to the intake valve 2 via the drive mechanism 6. , 2 at a position where the valve lift amount is held in the minimum lift range, the angle θ1 formed between the axis of the link member 48 and the axis of the screw shaft 45 is the maximum angle of about 65 °. As shown in FIG. 1, the axis of the link member 48 and the screw shaft 45 when the control shaft 32 is rotated clockwise and controlled by the second stopper pin 63 to the maximum lift. Is formed such that the angle θ3 formed with the axis is a minimum angle of about 35 °.

  Accordingly, the reduction ratio of the screw transmission means 37 to the rotation of the electric motor 36 is, as shown in FIG. 8, the angle θ formed by the axis of the screw shaft 45 and the axis of the link member 48 (the chain line in FIG. 8). As shown by the solid line in FIG. 8, the angle θ formed increases at the maximum angle θ1 at the time of the minimum lift as described above, and rapidly increases from the minimum lift to the minimum angle θ3 at the time of the maximum lift. Becomes smaller.

  Specifically, first, the reduction ratio is determined by the angular velocity of the screw shaft 45 / the angular velocity of the control shaft 32 as described above, and in the small lift region where θ is large, the screw nut 46 moves in the axial direction. Is not effectively converted into the rotation of the control shaft 32 due to the relationship with the link member 48, but the reduction ratio becomes large, but in the large lift region where θ is small, the axial movement of the screw nut 46 becomes the rotation of the control shaft 32. Since the conversion is effectively performed, the reduction ratio becomes small.

  Hereinafter, the operation of the present embodiment will be described. First, for example, in the low-rotation operation region including the idling operation of the engine, the rotational torque transmitted to the electric motor 36 by the control signal from the controller 40 is the screw shaft. When the rotation is transmitted to 45, the screw nut 46 is moved to the maximum rightward position as shown in FIG. 6, and thereby the control shaft 32 is rotated counterclockwise by the link member 48 and the linkage arm 47. Immediately before the side surface of the screw nut 46 is collided and locked in the axial direction, the side surface of the distal end portion 47b of the linkage arm 47 comes into contact with the first stopper pin 62 and further rotation is restricted. At this time, it is possible to prevent an impact load from being generated at the screwed portion between the screw nut 46 and the screw shaft 45 while ensuring the movable range of the screw nut 46.

  Therefore, as shown in FIGS. 3A and 3B, the control cam 33 rotates with the same radius around the axis P1 of the control shaft 32 as shown in FIGS. 3A and 3B, and the thick portion moves away from the drive shaft 13 upward. . As a result, the other fulcrum 23b of the rocker arm 23 and the pivot point of the link rod 25 move upward with respect to the drive shaft 13, so that each swing cam 17 is connected to the cam nose portion 21 via the link rod 25. The side is forcibly pulled up and the whole is rotated clockwise.

  Therefore, when the drive cam 15 rotates and pushes up the one end portion 23a of the rocker arm 23 via the link arm 24, the valve lift amount is transmitted to the swing cam 17 and the valve lifter 16 via the link rod 25. The lift amount L1 is sufficiently small.

  Therefore, in the low rotation region of such an engine, the valve lift amount becomes the smallest, so that the opening timing of each intake valve 2 is delayed, and the valve overlap with the exhaust valve is reduced. For this reason, improvement in fuel consumption and stable rotation of the engine can be obtained.

  Further, when the engine is shifted to the engine rotation region, the electric motor 36 is rotated in reverse by a control signal from the controller 40. When this rotational torque is transmitted to the screw shaft 45 and rotated, the screw nut 46 is rotated along with this rotation. It moves to the left from the position shown in FIG. Therefore, the control shaft 32 rotates the control cam 33 clockwise from the position shown in FIG. 3 to rotate the shaft center P2 slightly downward as shown in FIGS. 4A and 4B. For this reason, the entire rocker arm 23 moves toward the drive shaft 13 this time, and the other end 23b presses the cam nose portion 21 of the swing cam 17 downward via the link rod 25 so that the swing cam 17 The whole is rotated counterclockwise by a predetermined amount.

  Therefore, when the drive cam 15 rotates and pushes up the one end portion 23a of the rocker arm 23 via the link arm 24, the valve lift amount is transmitted to the swing cam 17 and the valve lifter 16 via the link rod 25. The lift amount L2 is slightly increased.

  Although the reduction ratio at this point is slightly smaller than the minimum lift region, the reduction ratio is also increased because the angle θ formed between the screw shaft 45 and the link member 48 is still relatively large. The electric current consumed by the electric motor 36 is small.

  Further, when the engine shifts to a high speed region, for example, when the vehicle suddenly accelerates, the electric motor 36 is controlled by a control signal from the controller 40 that detects this operation state from each sensor such as the engine speed sensor 41. The screw shaft 45 further rotates in the same direction by rotating in the reverse direction. With this rotation, the screw nut 46 moves greatly to the left as shown in FIG. 1, and the angle θ between the screw shaft 45 and the link member 48 becomes sufficiently small. Further, at this time, further movement is restricted at a position where the linkage arm 47 hits the second stopper pin 63 immediately before the side surface of the screw nut 46 is collided and locked in the axial direction. At that time, it is possible to prevent the screw nut 46 from being damaged due to the collision while securing the movable range of the screw nut 46. At this point, further movement of the screw nut 46 is also restricted, and the angle θ3 formed by the screw shaft 45 and the link member 48 is minimized.

  Along with this operation, the control shaft 32 rotates the control cam 33 clockwise from the position shown in FIG. 4, and the shaft center P2 moves downward as shown in FIGS. 5A and 5B. For this reason, the entire rocker arm 23 is moved in the direction of the drive shaft 13 and the cam nose portion 21 of the swing cam 17 is pressed downward via the link rod 25 by the other end portion 23b. Is rotated counterclockwise by a predetermined amount.

  Accordingly, the contact position of the cam surface 22 with respect to the upper surface of the valve lifter 16 of the swing cam 17 moves to the right position (lift side). For this reason, when the drive cam 15 rotates and the one end 23a of the rocker arm 23 is pushed up via the link arm 24 when the intake valve 12 is opened, the lift amount L3 with respect to the valve lifter 16 is larger than the intermediate valve lift amount L2. Become.

  Therefore, in such a high rotation region, the valve lift amount is maximized, the opening timing of each intake valve 2 is advanced, and the closing timing is delayed. As a result, the intake charging efficiency is improved and a sufficient output can be secured.

  As described above, the reduction ratio by the screw transmission means 37 is sufficiently large in the predetermined small lift range beyond the minimum lift range of the intake valves 2 and 2 that is the practical range of the vehicle. In addition, the rotational torque of the electric motor 36 required to rotationally drive the control shaft 32 via the link member 48 and the linkage arm 47 is reduced. For this reason, the power consumption by the electric motor 36 can be sufficiently reduced, and as a result, the fuel consumption of the internal combustion engine that drives the auxiliary machines such as the alternator is not affected.

  In addition, since the amount of electricity stored in the battery that supplies power to the electric motor 36 does not decrease, the amount of power supplied to the electric motor 36 can be secured, and the rotational operability of the electric motor 36 in the normal range of the vehicle is deteriorated. Can be prevented.

  Further, in the process of converting the intake valves 2 and 2 from the small lift region to the large lift region, the reduction ratio by the screw transmission means 37 is reduced, so that the actual rotational speed of the electric motor 36 required for the conversion is reduced. Therefore, the conversion time is shortened, and the deterioration of the operation responsiveness to the large valve lift can be prevented.

  Further, in this embodiment, since the first and second stopper pins 62 and 63 are provided to prevent the control shaft 32 from over-rotating, each stopper pin 62, The load input in one direction of the alternating torque can be suppressed by 63, and excessive movement of the screw nut 46 can also be prevented.

  Further, it is possible to suppress the generation of impact load at the screwed portion of the screw nut 46 and the screw shaft 45 while securing the movable range of the screw nut 46 by the both stopper pins 62 and 63.

  Further, the nut 52 is fastened to the other end 45b of the screw shaft 45 so that the inner ring 51a of the ball bearing 51 is sandwiched between the step portions of the screw shaft 45, so that the screw shaft 45 is maintained in a stable and smooth rotation. However, inadvertent movement in the axial direction can be restricted.

  FIG. 9 shows a second embodiment of the present invention, in which the link member 48 of the screw transmission means 37 is eliminated and a linkage lever 70 instead of the linkage arm 47 is linked directly to the screw nut 46.

  That is, the linkage lever 70 is formed in the shape of a raindrop that is long in the axial direction, the base portion 70a is fixed to the one end portion 32a of the control shaft 32, and the tip end portion extends to one lower side of the screw nut 46. An elongated slit 71 is formed along the longitudinal direction at approximately the center of 70b.

  On the other hand, the screw nut 46 has a transmission pin 72 rotatably attached at a substantially central position in the axial direction of one side portion. The transmission pin 72 is rotatably supported by a support hole having a base end portion drilled along the radial direction of the screw nut 46 and is slidably engaged with the distal end portion in the slit 71. Engagement surfaces 72a and 72b having a two-surface width are formed.

  Then, as shown in FIG. 9, the linkage lever 70 abuts against the second stopper pin 63 while being positioned in the direction perpendicular to the screw shaft 45 (about 90 °), and further rotates counterclockwise. At this point, the maximum lift is controlled via the control shaft 32. Therefore, by setting the maximum angle (about 90 °) in the large lift region, the reduction ratio becomes the smallest. It is formed as follows. This is because the movement of the screw nut 46 is effectively converted into the rotation of the linkage lever 70 by this large angle.

  On the other hand, as shown by a broken line in FIG. 9, the first stopper pin 62 is abutted against the screw shaft 45 at a predetermined tilt angle (about 45 °) and further clockwise rotation is restricted. At this time, the lift is controlled to the minimum lift, and therefore the reduction ratio is maximized by setting the minimum inclination angle (about 45 °) in the small lift region. This is because the movement of the screw nut 46 is not effectively converted into the rotation of the linkage lever 70 because the inclination angle becomes small.

  Therefore, according to this embodiment, when the screw shaft 45 is driven to rotate forward and backward by the electric motor 36 and the screw nut 46 linearly moves in the left-right axis direction of the screw shaft 45 as described above, the transmission pin 72 is moved. The linkage lever 70 rotates in the same direction via the slit 71, whereby the control shaft 32 rotates clockwise or counterclockwise, and the valve lift amount and operating angle of the intake valves 2 and 2 are controlled in magnitude. However, in the small lift region, as shown in FIG. 10, since the reduction ratio is large, the power consumption of the electric motor 36 is small. On the other hand, in the large lift region, as shown in the figure, since the reduction ratio is small, the power consumption increases, but the switching operation responsiveness by the variable mechanism 4 via the control shaft 32 is improved.

  Accordingly, the same operational effects as those of the first embodiment can be obtained, and the number of parts and the structure can be simplified as compared with the first embodiment, so that the manufacturing work and assembly work efficiency can be improved and the cost can be reduced. I can plan.

  The present invention is not limited to the configuration of the above-described embodiment. For example, the arrangement of the electric motor 36 can be freely changed depending on the layout of the engine room, and may be on the opposite left side instead of the right side shown in FIG. Further, the present invention can be applied to the exhaust valve side or both valve sides in addition to the intake valve side.

  The technical ideas other than the claims that can be grasped from the respective embodiments will be described below.

(B) The variable mechanism rotates in synchronization with the crankshaft of the engine, and is supported by a drive shaft having a drive cam on the outer periphery and a support shaft so as to be swingable, and the cam surface slides on the upper surface of the valve lifter. A rocking cam that contacts and opens and closes the engine valve; a rocker arm having one end mechanically linked to the drive cam and the other end linked to the rocking cam via a link rod;
By changing the rocking fulcrum of the rocker arm according to the engine operating state, the contact position of the cam surface of the rocking cam with the upper surface of the valve lifter is changed to make the valve lift of the engine valve variable. The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2,
(B) The output shaft is formed by a ball screw shaft, the threaded portion of the outer peripheral surface is formed in a spiral ball groove, and the moving member is formed in a ball screw nut, and the ball is formed on the inner peripheral surface. 3. The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the guide groove is formed in a guide groove for rotatably holding a plurality of balls in cooperation with the groove.

According to the present invention, since the ball is used as the driving means of the ball screw nut, the movement responsiveness is improved and the influence of the backlash is reduced as compared with the case of the driving means using only the male and female screws.
(C) The internal combustion engine according to claim 2, wherein the linkage portion is fixed to the control shaft, and is provided at a position where a pivotal support portion with the link member is eccentric from an axis of the control shaft. Variable valve gear.
(D) The angle formed between the link member and the output shaft is made the smallest when the operating angle of the engine valve is controlled to be the largest by the variable mechanism. A variable valve operating apparatus for an internal combustion engine as described.

According to the present invention, the reduction ratio can be reduced and the effect of reducing the radial load acting on the moving member at the maximum operating angle with a large input can be maximized, so that the threaded portion between the output shaft and the moving member can be obtained. The durability of can be improved.
(E) The angle formed between the link member and the output shaft is maximized when the operating angle of the engine valve is controlled to be the smallest by the variable mechanism. A variable valve operating apparatus for an internal combustion engine as described.

In the present invention, since the reduction ratio can be increased and the input is a small lift region, the radial load can be reduced in spite of the large angle, and the output shaft and the moving member can be reduced. It does not affect the durability of the threaded portion between them.
(F) A variable valve operating apparatus for an internal combustion engine according to claim 2, further comprising a restriction mechanism for restricting the maximum movement of the moving member in the axial direction.

According to this invention, since the maximum movement position of the moving member is restricted immediately before the moving member is collided and locked in the axial direction by the restriction mechanism, the output shaft and the moving member are secured while ensuring the moving range of the moving member. It is possible to suppress the generation of an impact load at the screwing site.
(G) The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the moving member is moved in the axial direction in a non-rotating state.

In this invention, since the moving member is in the non-rotating state, the rotational force of the output shaft can be efficiently converted into the axial direction moving force.
(H) the speed reduction means is linked to the electric motor and has an output shaft having a threaded portion on the outer periphery;
A moving member that is screwed into the screwing portion, moves in the axial direction of the output shaft as the output shaft rotates, and has a transmission pin on a side portion;
One end portion is fixed to the control shaft, and a slit formed in the other end portion includes a linkage lever linked to the transmission pin,
It is configured to rotate the control shaft via the linkage lever as the moving member moves in the axial direction,
2. The variable valve for an internal combustion engine according to claim 1, wherein an angle formed between the linkage lever and the output shaft is made small in a state in which the engine mechanism is controlled to have a small operating angle by the variable mechanism. apparatus.

It is a longitudinal cross-sectional view which shows the drive mechanism with which the 1st Embodiment of this invention is provided. It is a principal part perspective view of the variable valve apparatus of this embodiment. 2A is a view as viewed in the direction of an arrow A in FIG. 2 showing the valve closing action at the time of the minimum lift control in the present embodiment, and FIG. FIG. 2A is a view as viewed from an arrow A in FIG. 2 showing a valve closing action during middle lift control in the present embodiment, and B is a view as seen from an arrow A in FIG. 2 showing a valve opening action during the middle lift control. FIG. 2A is a view as viewed from an arrow A in FIG. 2 showing a valve closing action at the time of maximum lift control in the present embodiment, and B is a view as seen from an arrow A of FIG. It is operation | movement explanatory drawing of the drive mechanism at the time of the minimum lift control in this embodiment. It is a BB line expanded sectional view shown in Drawing 1 of this drive mechanism. It is a characteristic view which shows the relationship between the valve lift amount and reduction gear ratio in this embodiment. It is a principal part longitudinal cross-sectional view of the drive mechanism which shows the 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the valve lift amount and reduction ratio in 2nd Embodiment.

Explanation of symbols

1 ... Cylinder head 2 ... Intake valve (engine valve)
DESCRIPTION OF SYMBOLS 4 ... Variable mechanism 6 ... Drive mechanism 13 ... Drive shaft 15 ... Drive cam 17 ... Swing cam 32 ... Control shaft 33 ... Control cam 36 ... Electric motor (rotation force provision mechanism)
37 ... Screw transmission means 45 ... Screw shaft (output shaft)
46 ... Screw nut (moving member)
47. Linking arm (linking part)
48 ... Link member 49 ... Male screw part (screwing part)
55 ... Female thread part 62 ... First stopper pin (regulation mechanism)
63 ... Second stopper pin (regulation mechanism)
70 ... Linking lever 71 ... Slit 72 ... Transmission pin

Claims (4)

An internal combustion engine comprising: a variable mechanism that variably controls at least a valve lift amount of an engine valve by rotating a control shaft according to an engine operating state; and a drive mechanism that rotationally controls the control shaft via an electric motor and a speed reduction unit. In the variable valve system of the engine,
The speed reduction ratio of the speed reduction means is configured such that the state in which the valve lift amount of the engine valve is controlled to be the largest by the variable mechanism is the smallest, and the state in which the valve lift amount of the engine valve is controlled to be the smallest is the largest. A variable valve operating apparatus for an internal combustion engine. An internal combustion engine comprising: a variable mechanism that variably controls at least a valve lift amount of an engine valve by rotating a control shaft according to an engine operating state; and a drive mechanism that rotationally controls the control shaft via an electric motor and a speed reduction unit. In the variable valve system of the engine,
The speed reduction means is linked to the electric motor and has an output shaft having a threaded portion on the outer periphery;
A moving member that is screwed into the screwing portion and moves in the axial direction of the output shaft as the output shaft rotates;
A link member having one end portion pivotably linked to the moving member;
A link portion that is swingably linked to the other end of the link member, and that rotates the control shaft by a driving force transmitted from the link member as the moving member moves in the axial direction;
When the valve lift amount of the engine valve is controlled to be the largest by the variable mechanism, the angle formed by the link member and the output shaft is the smallest, and when the valve lift amount of the engine valve is controlled to be the smallest by the variable mechanism. A variable valve operating apparatus for an internal combustion engine, wherein the angle formed by the link member and the output shaft is maximized. A variable valve operating apparatus for an internal combustion engine, wherein a control shaft of a variable mechanism that variably controls at least a valve lift amount of an engine valve by rotating a control shaft according to an engine operating state is rotationally controlled via an electric motor and a speed reduction unit. In the drive mechanism,
The speed reduction ratio of the speed reduction means is configured such that the state in which the valve lift amount of the engine valve is controlled to be the largest by the variable mechanism is the smallest, and the state in which the valve lift amount of the engine valve is controlled to be the smallest is the largest. A drive mechanism for a variable valve operating apparatus for an internal combustion engine. A variable valve operating apparatus for an internal combustion engine, wherein a control shaft of a variable mechanism that variably controls at least a valve lift amount of an engine valve by rotating a control shaft according to an engine operating state is rotationally controlled via an electric motor and a speed reduction unit. In the drive mechanism,
The speed reduction means is linked to the electric motor and has an output shaft having a threaded portion on the outer periphery;
A moving member that is screwed into the screwing portion and moves in the axial direction of the output shaft as the output shaft rotates;
A link member having one end portion pivotably linked to the moving member;
A link portion that is swingably linked to the other end of the link member, and that rotates the control shaft by a driving force transmitted from the link member as the moving member moves in the axial direction;
When the valve lift amount of the engine valve is controlled to be the largest by the variable mechanism, the angle formed by the link member and the output shaft is the smallest, and when the valve lift amount of the engine valve is controlled to be the smallest by the variable mechanism. A drive mechanism for a variable valve operating apparatus for an internal combustion engine, characterized in that the angle formed by the link member and the output shaft is maximized.

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