JP4986900B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to an improved technique for a valve operating apparatus for an internal combustion engine that opens and closes an intake valve and an exhaust valve, which are engine valves.

  As this type of conventional valve gear, there is one described in the following Patent Document 1 previously filed by the present applicant.

  Briefly, this valve operating device is applied to the intake valve side, and a drive cam in which the shaft center is eccentric from the shaft center of the drive shaft on the outer periphery of the drive shaft to which the rotational force is transmitted from the crankshaft. And the rotational force of the drive cam is transmitted through a multi-joint link-like transmission mechanism comprising a link arm, rocker arm, link rod, etc., and the upper surface of the valve lifter at the upper end of the intake valve is cammed A rocking cam that slides on the surface and opens the intake valve against the spring force of the valve spring is provided. In addition, a control mechanism is provided that makes the lift amount of each intake valve variable according to the engine operating state.

  This control mechanism has a control shaft whose rotational position is controlled by an electric actuator, and a control cam that is fixed to the outer periphery of the control shaft and changes the rocking fulcrum position of the rocker arm.

Then, the rocking fulcrum of the rocker arm is changed by changing the rotation position of the control cam by rotating the control shaft by the electric actuator according to the engine operating state. As a result, the rolling contact position of the cam surface of each rocking cam with respect to the valve lifter upper surface during rocking changes, and the valve lift amount of the intake valve is variably controlled from the maximum lift to the minute lift.
JP 2004-293406 A

  In the conventional valve operating apparatus for an internal combustion engine, a timing sprocket that transmits rotational driving force from the crankshaft is attached to the tip of the drive shaft by a bolt. The timing sprocket is attached to the drive shaft. When mounting, a hexagonal detent for engaging a jig such as a spanner to prevent the drive shaft from rotating is provided at a predetermined position in the axial direction of the drive shaft.

  However, in addition to the drive shaft, the anti-rotation portion is joined to one side surface of a flange portion whose side end surface is fixed to a predetermined portion of the drive shaft for positioning in the axial direction. The outer peripheral edge (corner portion) of the part is formed not in a right angle but in a chamfered taper shape (R shape) in order to prevent generation of concentrated load.

  For this reason, the axial width length of the hexagonal outer surface of the anti-rotation portion becomes relatively short, and the area where the jig such as the spanner engages is reduced, and the contact area becomes small. As a result, there is a possibility that the rotation preventing force of the drive shaft by the jig becomes insufficient.

The present invention has been devised in view of the technical problem of the conventional valve gear, and the invention according to claim 1 provides a drive shaft to which power is transmitted from a crankshaft, and an outer periphery of the drive shaft. A drive cam that opens and closes an engine valve via a transmission mechanism, a large-diameter portion that is fixed at a predetermined position in the axial direction of the drive shaft, and that positions the drive shaft in the axial direction; A rotation-preventing mechanism that is provided between the drive cam and the large-diameter portion and prevents rotation of the drive shaft when a predetermined member is attached to the drive shaft;
A valve operating apparatus for an internal combustion engine comprising:
The anti-rotation mechanism is coupled to one side surface of the large-diameter portion, and has an anti-rotation portion having an outer peripheral surface formed in a non-circular shape, and is fitted to the outer peripheral surface of the anti-rotation portion. A fitting member having an engaging portion to be engaged, and the rotation preventing portion is formed with a tapered convex corner on an outer periphery of a side end surface coupled to one side surface of the large diameter portion. On the other hand, the fitting member is characterized in that a clearance groove for absorbing the corner portion is formed at the periphery of the fitting hole into which the rotation preventing portion is fitted.

  According to this invention, when the fitting member is fitted to the outer peripheral surface of the rotation preventing portion, the escape groove absorbs the tapered convex corner, and the inner surface of the fitting hole is formed on the entire outer peripheral surface. Since the non-rotating portion and the fitting member can be integrated because they are fitted in close contact, the fitting member has no arc-convex corner, so the axial length of its outer surface, that is, A sufficient contact area with the jig can be taken.

  Therefore, it is possible to sufficiently obtain the rotation preventing force of the drive shaft by the jig through the fitting member.

  Moreover, the axial length of the entire apparatus can be shortened by using the fitting member for positioning in the axial direction of a drive cam or the like.

  Embodiments of a valve operating apparatus for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In this embodiment, a valve operating device is applied to the intake side of an internal combustion engine of, for example, a V-type 6 cylinder, and the basic structure is common to the conventional technology.

  That is, as shown in FIGS. 5 and 6 showing one bank side of three cylinders, one cylinder that is slidably provided on the cylinder head 1 via a valve guide (not shown) and opens and closes two intake ports. Two intake valves 2, 2, a hollow internal drive shaft 3 arranged in the longitudinal direction of the engine, three drive cams 4 fixed for each cylinder of the drive shaft 3, and each intake air Between the swing cam member 6 that opens the intake valves 2 and 2 via the valve lifters 5 and 5 disposed at the upper ends of the valves 2 and 2, and between the drive cam 4 and the swing cam member 6. The transmission mechanism 7 is linked to convert the rotational force of the drive cam 4 into a swinging motion and is transmitted as the swinging force (valve opening force) of the swinging cam member 6, and the operating position of the transmission mechanism 7 is made variable. And a control mechanism 8 that variably controls the lift amount of the intake valves 2 and 2 in accordance with the engine operating state.

  As shown in FIG. 5, an exhaust side camshaft 9 is rotatably supported by a plurality of bearings such as a first bearing 10 on one end side on the side of the drive shaft 3 of the cylinder head 1. In addition, egg-shaped exhaust drive cams 9a, 9a for opening and closing two exhaust valves per cylinder via valve springs are integrally provided at predetermined positions in the axial direction of the exhaust camshaft 9. The exhaust-side camshaft 9 is adapted to transmit torque from the crankshaft of the engine via a timing sprocket 12 fixed to one end by a bolt 11 and a timing belt 13 wound around the timing sprocket 12. .

  The intake valves 2, 2 are connected to the intake port by valve springs 14, 14 elastically mounted between a bottom portion of a substantially cylindrical bore housed in the upper end portion of the cylinder head 1 and a spring retainer at the upper end portion of the valve stem. It is urged in the direction of closing each open end.

  The drive shaft 3 has one end portion and a predetermined axial portion rotatably supported by a first bearing portion 15 and other three bearings 16 and a driven sprocket fixed to one end portion by a bolt 17. Rotational force is transmitted from the crankshaft of the engine through the timing belt 13 wound around 18 and the driven sprocket 18.

  In addition, as shown in FIG. 5, the drive shaft 3 is integrally provided with a large-diameter and thick first flange portion 3a at the one end portion, and the journal portion 3b is sandwiched from the first flange portion 3a. A second flange portion 3c, which is a large diameter portion, is integrally provided at the opposite position.

  As shown in FIGS. 3 and 6, each of the drive cams 4 is formed in a substantially disc shape, and a cylindrical portion 4b is integrally provided on a side portion of the cam body 4a. The fixing shaft 30 is press-fitted from the diameter direction 4b and is fixed to the drive shaft 3 respectively. The cam body 4a has an outer circumferential surface formed into an eccentric cam profile, and the shaft center is offset from the shaft center X of the drive shaft 3 by a predetermined amount in the radial direction.

  As shown in FIGS. 5 and 6, each swing cam member 6 is integrally formed with a cylindrical portion 6 a that is slidably supported on the outer peripheral surface of the drive shaft 3, and at both ends of the cylindrical portion 6 a. A pair of raindrop-like rocking cams 6b and 6b are provided and are in sliding contact with the crown surfaces of the valve lifters 5 and 5, respectively. The cylindrical portion 6a is swingably provided on each bearing 16 via a journal portion 6c formed between the swing cams 6b and 6b.

  The cam surfaces are respectively formed on the lower surface of each swing cam 6b, a base circle surface on the base end side, a ramp surface extending in an arc from the base circle surface to the cam nose portion side, and a cam nose portion from the ramp surface A lift surface that is continuous with the top surface of the maximum lift that is provided on the tip end side of the rocking cam 6 is formed. The base circle surface, the ramp surface, the lift surface, and the top surface are in accordance with the swing position of the swing cam 6. It comes into contact with the 5 crown surface.

  Further, on the cam nose portion side of the swing cam 6, pin holes through which pins to be connected to the other end portion of the link rod described later are inserted are formed in both side surfaces.

  As shown in FIG. 6, the transmission mechanism 7 includes a rocker arm 19 disposed above the drive shaft 3, a link arm 20 that links the one end of the rocker arm 19 and the drive cam 4, and the other end of the rocker arm 19. And a pair of link rods 21 that link the cam nose portion of one swing cam 6b.

  The rocker arm 19 is formed in a flat crank shape, and one end 19a projecting from the central cylindrical base to the inside of the engine is rotatably connected to the projecting end of the link arm 20 via a pin 18, The other end protruding to the outside of the engine is rotatably connected to one end of the link rod 21 by a pin 22. A large-diameter support hole is formed through the cylindrical base.

  The link arm 20 includes an annular portion 20a having a relatively large diameter and the projecting end 20b projecting at a predetermined position on the outer peripheral surface of the annular portion. A fitting hole 20c for fitting and supporting the outer peripheral surface of the drive cam 4 in a rotatable manner is formed. Further, the axial length of the annular portion 20 is set to be substantially the same as the width of the cam body 4 a of the drive cam 4.

  Each of the link rods 21 is integrally formed by press molding and has a substantially U-shaped cross section, and the other end of each link rod 21 swings through a pin 23 inserted into each formed pin hole. The cam 6b is rotatably connected to a cam nose portion.

  The control mechanism 8 includes a control shaft 24 disposed above the drive shaft 3, a control cam 25 that is integrally fixed to the outer periphery of the control shaft 24 and serves as a rocking fulcrum of the rocker arm 19, and the control shaft 24. And a drive unit for controlling the rotation of the motor.

  The control shaft 24 is disposed in parallel with the drive shaft 3 in the longitudinal direction of the engine and is rotatably supported by a bearing, while the control cam 25 has a cylindrical shape and the shaft center position is a thick part. It is deviated from the axis of the control shaft 24 by a predetermined amount.

  The drive unit includes an electric motor 26 fixed to the rear end of the cylinder head 1 and a ball screw mechanism 27 that is a reduction gear that transmits the rotational driving force of the electric motor 26 to the control shaft 24. Yes.

  The electric motor 26 is constituted by a proportional type DC motor, and is driven by a control signal from a controller 28 that detects the operating state of the engine. The controller 28 includes various sensors such as a crank angle sensor that detects the engine speed, an air flow meter that detects the intake air amount, a water temperature sensor that detects the water temperature of the engine, and a potentiometer 29 that detects the rotational position of the control shaft 24. A detection signal from the sensor is fed back to detect the current engine operating state by calculation or the like, and a control signal is output to the electric motor 26.

  And between the 2nd flange part 3c of the said drive shaft 3, and the drive cam 4, when fixing the timing pulley 18 to the said drive shaft 3 with the volt | bolt 17, the rotation stop which performs rotation prevention etc. of the drive shaft 3 is carried out. A mechanism 31 is provided.

  As shown in FIGS. 1 to 4, the anti-rotation mechanism 31 is integrally provided on the outer peripheral surface of the drive shaft 3, and the side end surface is coupled to one side surface 3d of the second flange portion 3c by welding or the like. The stopper 32 and the fitting member 33 fitted and held on the outer surface of the stopper 32 are configured.

  The anti-rotation portion 32 is integrally fixed by welding or the like, and the outer peripheral surface 32a is formed in a hexagonal shape having a non-circular shape. Further, a tapered convex corner 32b is formed on the outer peripheral edge of the side end face coupled to the one side surface 3d to the second flange part 3c of the rotation preventing part 32. The corner portion 32b prevents concentrated load at the joint portion with the second flange portion 3c, and is usually referred to as an R portion. In addition, the said rotation stop part 32 can also be formed integrally when shape | molding the drive shaft 3, If it does in this way, manufacture will also become easy.

  On the other hand, the entire fitting member 33 is formed of a ferrous metal material into a hexagonal annular shape, and the inner surface 33b of the hexagonal fitting hole 33a is formed substantially the same as the shape of the outer surface 32a of the anti-rotation portion 32. Thus, the fitting hole 33a can be fitted to the outer peripheral surface 32a, and the width length W of the outer surface 33c is formed larger than the width length W1 of the outer surface 32a of the detent portion 32. . Further, tapered escape grooves 33d and 33d for absorbing the corner portion 32b are formed on the entire circumference of both peripheral edges of the inner surface 32b of the fitting hole 33a. The outer surface 33c, which is an engaging portion, is also formed in a hexagonal shape.

  Further, as shown in FIG. 4, when the fitting member 33 is fitted to the outer peripheral surface 32a of the rotation preventing portion 32, the one end surface comes into contact with one side surface 3d of the second flange portion 3c. The other end surface comes into contact with one side surface of the cam body 4a of the drive cam 4 and functions as a collar for positioning the drive cam 4 and the link arm 20 in the axial direction.

  Hereinafter, the operation of the present embodiment will be described. First, in a low rotation range such as when the engine is idling, the electric motor 26 of the drive unit is rotationally driven by a control signal from the controller 28, and this rotational torque is This is transmitted to the control shaft 24 via the ball screw mechanism 27, and the control shaft 24 is rotated by a predetermined amount in one direction. Therefore, the control shaft 24 rotates the control cam 25 in one direction, the shaft center rotates around the shaft center of the control shaft 24 with the same radius, and the thick portion moves away from the drive shaft 3 upward. To do. As a result, the other end of the rocker arm 19 and the pivot point of the link rod 21 move upward with respect to the drive shaft 3, so that the swing cam 6 b is forced on the cam nose side via the link rod 21. To be raised.

  Therefore, when the drive cam 4 rotates and pushes up one end portion of the rocker arm 19 via the link arm 20, the valve lift amount is transmitted from the swing cams 6b, 6b to the valve lifters 5, 5 via the link rod 21. The lift amount 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 3 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, for example, in the case of shifting to the high engine rotation range, when the electric motor 26 rotates in reverse by the control signal from the controller 28 and rotates the ball screw mechanism 27 in the same direction, the control shaft 24 is rotated along with this rotation. The control cam 25 is rotated in the other direction, and the axis moves downward. For this reason, the rocker arm 19 is now moved in the direction of the drive shaft 3 and the cam nose portion of the swing cam 6b is pressed downward by the other end portion via the link rod 21 to thereby move the swing cams 6b, 6b. The whole is rotated counterclockwise by a predetermined amount.

  Therefore, the contact position of the cam surface with respect to the valve lifter 5 of each swing cam 6b, 6b moves to the cam nose part side (lift part side). For this reason, if the drive cam 4 rotates and the one end part of the rocker arm 19 is pushed up via the link arm 20 when each intake valve 2 is opened, the lift amount with respect to the valve lifter 5 becomes sufficiently large.

  Therefore, in such a high rotation region, the valve lift amount becomes maximum, the opening timing of each intake valve 3 is advanced, and the closing timing is delayed. As a result, the intake charging efficiency is improved and a sufficient output can be secured.

  In this embodiment, when the fitting member 33 is fitted to the outer surface 32a of the rotation preventing portion 32, the escape groove 33d is in a state of absorbing the corner portion 32b and is fitted to the entire outer surface 32a and the corner portion 32b. Since the inner surface 33b of the hole 33a and the inner surface of the escape groove 33d are fitted in close contact with each other, the rotation preventing portion 32 and the fitting member 33 can be integrated, and the fitting member 33 has arcuate corners. Since it does not exist, the width W of the outer surface 33c can be formed sufficiently large.

  Therefore, when the timing pulley 18 is fixed to the one end portion of the drive shaft 3 by the bolt 17 by hand, the spanner as a jig is engaged with the outer surface 33c of the fitting member 33. And a sufficient contact area between the outer surface 33c and the outer surface 33c. Therefore, a sufficient detent force of the drive shaft 3 by the spanner can be obtained through the fitting member 33.

  Moreover, since the fitting member 33 also functions as an axial positioning collar for the drive cam 4 and the link arm 20 as described above, it is not necessary to provide a positioning collar separately, thereby reducing the number of parts. As a result, the assembly work efficiency of each component can be improved and the cost can be reduced.

  In addition, since the fitting member 33 can be used as an axial positioning collar, the axial length of the drive shaft 3 can be shortened. That is, in the valve operating apparatus provided with the variable lift mechanism, it is necessary to provide a driving unit such as the electric motor 26 and the ball screw mechanism 27 at the end of the control shaft 24, and the axial length of the entire apparatus. However, it is desired to slightly reduce the axial length from the request for ease of mounting on the engine and weight reduction.

  Therefore, in this embodiment, since the fitting member 33 is also used as a collar without providing a positioning collar, the length in the axial direction of the apparatus can be shortened by the amount of provision of the collar. .

  Further, since the escape grooves 33d and 33d are formed in the front and rear peripheral edges of the inner surface 33b of the fitting hole 33a, the fitting member 33 can be fitted to the anti-rotation portion 32 from either the front or the rear. As a result, erroneous assembly can be avoided and fitting work is facilitated.

  The present invention can be applied not only to the valve operating device having the lift variable mechanism of the intake valves 2 and 2 as in the above embodiment, but also to a general valve operating device. In addition, the present invention can be applied to the exhaust side or both.

  Further, the outer surface 32a of the anti-rotation portion 32 may be non-circular, and may be formed in a polygonal shape such as a quadrangular shape or a triangular shape. In this case, of course, the shape of the fitting hole 33a of the fitting member 33 is formed in accordance with it. Further, the outer surface 33c of the fitting member 33 is not necessarily formed in a hexagonal shape, and may be formed in a polygonal shape.

It is an expansion perspective view which decomposes | disassembles and shows the rotation stop mechanism provided for one Example of this invention. It is an expansion perspective view of the same rotation stop mechanism. It is an expansion perspective view which shows the state in which the drive cam and the link arm were positioned in the axial direction by the same rotation prevention mechanism. It is sectional drawing which shows the state in which the drive cam and the link arm were positioned by the rotation prevention mechanism in the axial direction. It is a top view which shows a part of valve operating apparatus in a present Example in cross section. It is a perspective view which shows a part of valve operating apparatus in a present Example.

Explanation of symbols

1 ... Cylinder head 2 ... Intake valve (engine valve)
DESCRIPTION OF SYMBOLS 3 ... Drive shaft 3a ... 1st flange part 3b ... Journal part 3c ... 2nd flange part (large diameter part)
DESCRIPTION OF SYMBOLS 4 ... Drive cam 4a ... Cam main body 4b ... Cylindrical part 6 ... Swing cam member 6b ... Swing cam 7 ... Transmission mechanism 8 ... Control mechanism 10.15 ... 1st bearing part 18 ... Timing pulley 20 ... Link arm 20a ... Circle Ring part 31: Anti-rotation mechanism 32 ... Anti-rotation part 32a ... Outer surface 32b ... Corner 33 ... Fitting member 33a ... Fitting hole 33b ... Inner surface 33c ... Outer surface 33d ... Escape groove

Claims (4)

A drive shaft to which power is transmitted from the crankshaft;
A drive cam fixed to the outer periphery of the drive shaft and opening / closing the engine valve via a transmission mechanism;
A large-diameter portion that is fixed at a predetermined position in the axial direction of the drive shaft and that positions the drive shaft in the axial direction;
An anti-rotation mechanism provided between the drive cam and the large-diameter portion and configured to prevent rotation of the drive shaft when a predetermined member is attached to the drive shaft;
A valve operating apparatus for an internal combustion engine comprising:
The anti-rotation mechanism is coupled to one side surface of the large-diameter portion, and has an anti-rotation portion having an outer peripheral surface formed in a non-circular shape, and is fitted to the outer peripheral surface of the anti-rotation portion. A fitting member having an engaging portion to be engaged,
While the anti-rotation portion has a tapered convex corner formed on the outer periphery of the side end surface coupled to one side surface of the large diameter portion,
The valve operating device for an internal combustion engine, wherein the fitting member is formed with a clearance groove for absorbing the corner portion at a peripheral edge of a fitting hole into which the rotation preventing portion is fitted. The valve operating apparatus for an internal combustion engine according to claim 1,
A link arm that constitutes a part of the transmission mechanism is provided on the outer periphery of the drive cam, and the axial cam positioning of the drive cam of the link arm is performed by the anti-rotation portion and a fitting member. Valve operating device. The valve operating apparatus for an internal combustion engine according to claim 1 or 2,
A swing cam member that opens and closes the engine valve is swingably supported on the outer periphery of the drive shaft by a swing force transmitted from the drive cam via a transmission mechanism, and the fitting member is A valve operating apparatus for an internal combustion engine, which is also used as a collar for positioning the swing cam member in the axial direction through a diameter portion. The valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
While forming the outer peripheral surface of the non-rotating portion to be a substantially hexagonal surface, the inner surface of the fitting hole of the fitting member is formed to a hexagonal surface corresponding to the outer peripheral surface of the anti-rotating portion, and the fitting member A valve operating apparatus for an internal combustion engine, wherein an outer surface is formed as a hexagonal surface.

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