JPH07286507A - Cam angle adjusting device - Google Patents

Abstract

PURPOSE:To reduce the number of positions where backlash in a rotation force transmission passage from a rotary member to a cam occurs and reduce the amount of deviation of an actual cam angle for a target cam angle in a cam angle adjusting device which adjusts a cam angle as a rotation angle of the cam from the start of the operation of a follow-up member to the end of the operation. CONSTITUTION:A cam angle ad justing device is provided with an outer cam shaft 14 consisting of an outer shaft main body 15 and a first cam, an inner cam shaft 17 consisting of an inner shaft main body 18 and a second cam, a timing pulley 22 on the outer periphery of the shaft main body 15, a slider 28 between the shaft main bodies 15 and 18, and a slider drive mechanism M1. The slider 28 is spline-coupled to both shaft bodies 15, 18 by helical splines 28a, 28b on the inner and outer peripheries of the slider 28. The drive means M1 moves the slider 28 along axial lines L1, L2 to adjust a cam angle and changes rotation phase of the cam shafts 14, 17 for the pulley 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which a driven member such as an intake / exhaust valve is cyclically actuated by a cam. The present invention relates to a cam angle adjusting device that adjusts a rotation angle (cam angle).

[0002]

2. Description of the Related Art In a general internal combustion engine, intake valves and exhaust valves are periodically pushed down (lifted) by rotation of a cam to open intake ports and exhaust ports. In recent years, various cam angle adjusting devices have been proposed which adjust the rotation angle (cam angle) of a cam from the start of lift of these intake / exhaust valves to the end of the lift. As one of them, Shoukai 60-141
An example is the "profile variable cam device" disclosed in Japanese Patent No. 406.

As shown in FIG. 15, this device comprises an outer camshaft 101 and an inner camshaft 104. The outer camshaft 101 has a cylinder head 108.
The outer shaft body 102 is rotatably supported by the outer shaft body 102 and the first cam 103 fixed to the shaft body 102. The inner cam shaft 104 is an inner shaft body 105 that is rotatably inserted in the outer shaft body 102, and a second cam that is loosely fitted to the outer periphery of the shaft body 102 and fixed to the inner shaft body 105 by a pin 107. And 106. Both cams 10
3 and 106 periodically push down (lift) the intake valve (or exhaust valve) 109. The cam angle becomes the smallest when both cams 103 and 106 overlap each other, and becomes larger when both cams 103 and 106 are displaced from each other in the rotational direction due to the relative rotation of both cam shafts 101 and 104.

A timing pulley 111 is rotatably provided on the outer periphery of the end portion of the outer shaft body 102.
A timing belt 112 is wound around the pulley 111, and the rotation of a crankshaft (not shown) is transmitted to the pulley 111 via the belt 112.

As shown in FIG. 14, the timing pulley 1
11 and the outer camshaft 101 are formed with notches 111a and 101a extending in a direction intersecting with each other, and a first slider 113 is fitted and inserted at the intersecting portion. The first slider 113 has the notches 111a and 101a.
a pair of rollers 113a and 113b arranged in a,
It is composed of a shaft portion 113c connecting these. Similarly, the outer camshaft 101 and the inner camshaft 104 are
The two sliders 114a and 114b and the shaft portion 114c are connected by a second slider 114.

The profile type variable cam device includes a first slider 113 for driving the first slider 113 in the direction of the axis L8.
A slider drive mechanism 115 is provided. This mechanism 1
Reference numeral 15 denotes a step motor 116, a rotary shaft 117 driven by the motor 116, a nut 118 screwed onto the rotary shaft 117 so as not to rotate and movable in the direction of the axis L8, and a first slider 113. It is composed of a fixed annular member 119 and a bearing 121 arranged between the nut 118 and the annular member 119. Further, the second slider driving mechanism 12 having the same structure as the first slider driving mechanism 115 for driving the second slider 114 in the direction of the axis L8.
Two are provided.

According to the above apparatus, the timing pulley 11
At the time of one rotation, the rotational force is applied to both sliders 113, 11
4 is transmitted to the outer camshaft 101 and the inner camshaft 104, respectively. Both camshafts 10
As the cams 1 and 104 rotate, both cams 103 and 106 rotate, and the intake valve (or exhaust valve) 109 is lifted periodically. When the first slider driving mechanism 115 moves the first slider 113 along the axis L8 while the timing pulley 111 rotates, the timing pulley 111
And both camshafts 101 and 104 rotate relative to each other. In addition, the second slider drive mechanism 122 causes the second slider 1 to move.
When 14 moves in the direction of the axis L8, the outer camshaft 1
01 and the inner camshaft 104 rotate relative to each other. The cam angle is adjusted by these relative rotations.

[0008]

However, in the prior art, the timing pulley 111, the first slider 113, the outer camshaft 101, the second slider 114, and the second slider 114 are provided in the rotational force transmission path from the timing belt 112 to the second cam 106. The inner camshaft 104 is interposed.
Among these, between the timing pulley 111 and the roller 113a, between the roller 113b and the outer camshaft 101, between the outer camshaft 101 and the roller 114a,
Backlash occurs at each of four positions between the roller 114b and the inner camshaft 104. The backlash at each point is small, but the total backlash of each value is too large to be ignored. Due to this total backlash, a large deviation occurs between the target cam angle and the actual cam angle.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to reduce the occurrence of backlash in a rotational force transmission path from a rotary member such as a timing pulley to a cam and to achieve a target cam angle. It is an object of the present invention to provide a cam angle adjusting device that can reduce the actual deviation amount of the cam angle with respect to.

[0010]

In order to achieve the above object, a first invention according to a first aspect of the present invention is provided with a cylindrical outer shaft main body, and the outer shaft main body is integrally rotatably provided and An outer camshaft having a first cam for periodically actuating the driven member by a rotational movement, and an inner shaft body inserted into the outer camshaft,
And an inner cam shaft integrally rotatably provided on the inner shaft main body and having a second cam for cyclically actuating the driven member together with the first cam by the rotational movement thereof, and an outer circumference of the outer shaft main body. A rotating member that is rotatably provided, and is interposed between the outer shaft body and the inner shaft body, is attached to the rotating member so as to be integrally rotatable, and reciprocally movable in the axial direction of both cam shafts, A slider that has helical splines that intersect with the axis on its inner circumference and outer circumference, and that is splined to the outer shaft body and the inner shaft body by these helical splines,
The slider is moved along the axis to adjust the cam angle, which is the rotation angle of the first cam and the second cam from the start of the operation of the driven member to the end of the operation, and the rotary member is moved. And a slider drive mechanism for changing the rotational phase of both cam shafts.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the driven member is an intake valve and an exhaust valve of an internal combustion engine, and the outer camshaft and the inner camshaft are both valves. Corresponding to one valve, the slider, the rotating member and the slider drive mechanism are provided corresponding to one valve, and the outer drive gear is attached to the outer shaft body corresponding to the one valve. , While attaching the inner drive gear to the inner shaft body connected by the slider, attach the outer driven gear to the outer shaft body corresponding to the other valve, and attach the inner driven gear to the inner shaft body corresponding to the same valve. A biasing member that meshes both driven gears with both drive gears and further biases the outer driven gear and the inner driven gear to rotate in opposite directions. Only to have.

[0012]

In the first aspect of the present invention, when a rotational force is applied to the rotating member, the rotational force is transmitted to the first cam through the spline connecting portion between the slider and the outer shaft body and the outer shaft body in this order. Further, the rotational force is transmitted to the second cam through the spline connection portion between the slider and the inner shaft body and the inner shaft body in this order. Due to these transmissions, the first cam and the second cam rotate together, and the driven member is operated periodically.

In the transmission path of the rotational force from the rotating member to the first cam, the location where the backlash occurs is the spline connecting portion between the slider and the outer shaft body. In the transmission path of the rotational force from the rotating member to the second cam, the location where the backlash occurs is the spline connecting portion between the slider and the inner shaft body. As described above, the backlash is generated at the spline joint portion on the inner and outer circumferences of the slider, and the number thereof is half that of the conventional technique. As a result, the deviation of the actual cam angle from the target cam angle can be made smaller than that of the conventional technique.

When the slider is moved by the slider driving mechanism along the axes of both the inner and outer camshafts, the splines on the inner and outer circumferences of the slider are helical splines intersecting the axis. Torsional force is applied to each camshaft. Due to this twisting force, both the inner and outer cam shafts rotate relative to the slider, and the cam angle is changed.

In the second invention, one of the intake valve and the exhaust valve of the internal combustion engine is driven in the same manner as in the first invention. That is, when a rotational force is applied to the rotating member, the rotational force is transmitted to the first cam through the spline coupling portion between the slider and the outer shaft body and the outer shaft body in this order. In addition, the rotational force is transmitted to the second cam through the spline coupling portion between the slider and the inner shaft body and the inner shaft body in this order. Due to these transmissions, both the first cam and the second cam rotate, and one valve is operated periodically.

The rotation of the outer camshaft is transmitted to the outer camshaft (or inner camshaft) for driving the other valve via the drive gear and the driven gear. Further, the rotation of the inner camshaft is transmitted to the inner camshaft (or the outer camshaft) for driving the other valve via the drive gear and the driven gear. The outer cam shaft, to which the rotational force is transmitted via the outer driven gear, rotates integrally with the first cam. Similarly, the inner cam shaft, to which the rotational force is transmitted via the inner driven gear, rotates integrally with the second cam. The rotation of these cams periodically activates the other valve.

When the slider is moved along the axis by the slider drive mechanism, a twisting force is applied to the outer camshaft and the inner camshaft, and both the inner and outer camshafts rotate relative to the slider. By this relative rotation,
The cam angle of the cam for driving one valve is adjusted. Further, the relative rotation is transmitted to both the inner and outer camshafts for driving the other valve via the drive gear and the driven gear as described above. By this transmission, the first and second
Each cam angle of the cam is adjusted. In this way, the cam angle of each cam on the intake valve side and the exhaust valve side is adjusted by one slider drive mechanism.

Further, the outer driven gear attached to the outer cam shaft and the inner driven gear attached to the inner cam shaft are rotationally biased in opposite directions by the biasing member. The rotational urging force at this time is transmitted to both drive gears meshing with both driven gears and both inner and outer camshafts to which the respective drive gears are attached. The directions of the rotational urging forces transmitted to both drive gears are opposite to each other. The directions of the rotational biasing forces transmitted to the outer cam shaft and the inner cam shaft are opposite to each other. Furthermore, the direction of the rotational urging force transmitted from the outer camshaft to the slider and the direction of the rotational urging force transmitted from the inner camshaft to the slider are opposite to each other.

Therefore, backlash may occur at the spline connecting portion between the slider and the inner camshaft, the spline connecting portion between the slider and the outer camshaft, and the meshing portion of the drive gear and the driven gear. However, each backlash is canceled by the rotational biasing force.

[0020]

【Example】

(First Embodiment) Hereinafter, the cam angle adjusting device of the first invention will be described.
The first applied to a valve mechanism for intake valves of a multi-cylinder internal combustion engine
An embodiment will be described with reference to FIGS.

As shown in FIG. 6, an intake port 4 communicating with a combustion chamber 3 of each cylinder is formed in a cylinder head 2 of an engine 1 as an internal combustion engine. An annular valve seat 5 is attached to the opening of the intake port 4 in each combustion chamber 3.

The cylinder head 2 is provided with an intake valve 6 as a driven member for periodically opening and closing each intake port 4. Each intake valve 6 extends in a substantially vertical direction in a slightly inclined state and extends in the cylinder head 2
The stem portion 6a slidably inserted into the stem portion 6a and the umbrella portion 6b formed at the lower end of the stem portion 6a. Then, when each intake valve 6 moves upward and the umbrella portion 6b contacts the valve seat 5, the intake port 4 is closed. When each intake valve 6 moves downward and the umbrella portion 6b separates from the valve seat 5, the intake port 4 is opened.

A guide hole 7 corresponding to the intake valve 6 is provided through the cylinder head 2, and a valve lifter 8 is slidably inserted therein. A shim 9 is fitted on the upper portion of each valve lifter 8. The upper end of each stem portion 6 a is in contact with the inner wall surface of the valve lifter 8. A valve spring retainer 12 is attached to the upper end of each stem portion 6a via a cotter 11. A valve spring 13 is mounted in a compressed state between each retainer 12 and the support surface 2a in the cylinder head 2. Each spring 13 biases the intake valve 6 upward, which is the direction of closing the intake port 4.

A mechanism is provided above the valve lifter 8 for opening and closing each intake port 4 by periodically pushing down (lifting) each intake valve 6 against the urging force of the valve spring 13. Has been. The cam angle adjusting device of this embodiment is incorporated in this mechanism.

As shown in FIGS. 1 to 3, an outer camshaft 14 is rotatably supported on the cylinder head 2. The outer camshaft 14 includes an outer shaft body 15 having a substantially cylindrical shape. In the outer shaft body 15, the first cam 16 is provided at a position corresponding to each intake valve 6.
Is rotatably provided. The first cam 16 may be formed integrally with the outer shaft body 15,
It may be fixed. The first cam 16 is composed of a buffer portion 16a having an annular shape, and a lifting portion 16b protruding outward from the buffer portion 16a in the radial direction. The tip of the lifting portion 16b is formed into a curved surface with a large radius of curvature centered on the axis L1 of the outer camshaft 14.

In the first cam 16, the pushing-down force does not act on the intake valve 6 when the buffer portion 16a is in contact with the shim 9. The first cam 16 rotates, and the contact portion with respect to the shim 9 moves from the buffer portion 16a to the lift portion 16b.
When shifting to, the pushing-down force starts to act on the intake valve 6, and the lift of the valve 6 is started. First cam 16
The lift amount of the intake valve 6 changes according to the rotation of. Then, when the contact portion with respect to the shim 9 moves from the lift portion 16b to the buffer portion 16a, the pushing-down force with respect to the intake valve 6 disappears and the lift of the valve 6 is terminated.

An inner camshaft 17 having a square rod-shaped inner shaft body 18 is inserted into the outer shaft body 15. A second cam 19 is integrally rotatably attached to a portion of the inner shaft body 18 corresponding to each intake valve 6. That is, a square hole 19a is provided at the center of each second cam 19, and the inner shaft body 18 is fitted therein. The second cam 19 has a lifting portion 19b having the same shape as the first cam 16. The lifting portion 19b is provided on the outer shaft main body 15 by
It penetrates through an opening 21 formed near the side of the first cam 16. The axis line L2 of the inner camshaft 17 coincides with the axis line L1 of the outer camshaft 14.

Here, the first cam 16 and the second cam 16 from the start of the lift of the intake valve 6 to the end of the lift.
The rotation angle of the cam 19 is referred to as a cam angle Δθ. Then, the cam angle Δθ is determined when both cams 16 and 19 overlap (see FIG. 4).
It becomes the smallest in (a)). Both camshafts 14, 17
Is relatively rotated and both cams 16 and 19 are displaced in the rotational direction, the cam angle Δθ is enlarged.

As shown in FIG. 1, a timing pulley 22 as a rotating member is externally fitted to the left end of the outer camshaft 14 so as to be relatively rotatable. A timing belt 23 is wound around the pulley 22, and the rotation of a crankshaft (not shown) is transmitted to the pulley 22 via the belt 23.

A substantially bottomed cylindrical case 24 is fastened to the left end portion of the inner shaft body 18 with a bolt 25. Case 24 and inner camshaft 17 are pin 2
They are connected by 6 so that they rotate together.

An annular space 27 is formed by the timing pulley 22, the case 24 and the outer camshaft 14.
A slider 28 having a substantially cylindrical shape is arranged here. The slider 28 is provided with a plurality of (two shown in FIG. 1) elongated holes 29 extending in parallel to the axes L1 and L2, and a connecting pin 31 protruding from the timing pulley 22 is provided in each hole 29. It is slidably fitted. Therefore, the slider 28 can rotate integrally with the timing pulley 22 and can reciprocate in the directions of the axes L1 and L2.

The outer camshaft 14 and the case 24 are drivingly connected by a slider 28. That is, on the inner and outer circumferences of the slider 28, helical splines 28a, which intersect the axes L1 and L2 at a predetermined angle,
28b is formed. Corresponding to these helical splines 28a and 28b, helical splines 15a and 24b are formed on the outer peripheral surface of the outer shaft main body 15 and the inner peripheral surface of the case 24, respectively. The helical splines 15a and 28a mesh with each other (spline coupling), and the helical splines 24b and 28b mesh with each other (spline coupling). On the inner circumference and the outer circumference of the slider 28, the extending directions of the helical splines 28a and 28b intersect with each other.

Therefore, when the rotation of the crankshaft is transmitted to the timing pulley 22 via the timing belt 23, the slider 28 rotates integrally with the timing pulley 22. The outer camshaft 14 and the case 24 (inner camshaft 17) connected by the slider 28 are integrally rotated.

A pressure chamber 32 is provided on the left side of the slider 28 in the annular space 27, and hydraulic oil 33 is supplied to the pressure chamber 32. More specifically, hydraulic oil 33 is provided between the case 24, the inner shaft body 18, and between the shaft bodies 15 and 18.
Supply path 34 is formed. One end of the supply path 34 communicates with the pressure chamber 32, and the other end is connected to an oil pan 36 via an oil pump 35. The oil pump 35 is drivingly connected to the crankshaft, and pumps up the hydraulic oil 33 in the oil pan 36 in conjunction with the operation of the engine 1.
Discharge. The discharged hydraulic oil 33 is supplied into the pressure chamber 32 through the supply passage 34. By this supply, hydraulic pressure to the right acts on the left side surface of the slider 28.

On the other hand, the slider 28 in the annular space 27
A spring chamber 37 is provided on the right side of. In the spring chamber 37, coil springs 38 and 39 are housed in a compressed state on the inner peripheral side and the outer peripheral side of the connecting pin 31, respectively. Both coil springs 38 and 39 constantly urge the slider 28 to the left. And the slider 2
8 so that the hydraulic pressure acting from the pressure chamber 32 side and the biasing force of the coil springs 38 and 39 are balanced.
The slider 28 moves in the left-right direction while rotating.

A portion of the case 24 facing the pressure chamber 32 serves as a stopper 41 for preventing the slider 28 from further moving when the slider 28 is moved to the leftmost side by the coil springs 38 and 39. Further, a portion of the timing pulley 22 facing the spring chamber 37 serves as a stopper 42 for preventing the slider 28 from further moving when it is moved to the rightmost side by hydraulic pressure.

A discharge passage 43 is formed in the outer camshaft 14 for discharging the hydraulic oil 33 that has entered the spring chamber 37 from the pressure chamber 32. One end of the discharge passage 43 is open to face the spring chamber 37, and the other end is connected to the oil pan 36.

A hydraulic control valve 44 for opening and closing the supply passage 34 and switching the stop position of the slider 28 is provided between the supply passage 34 and the oil pump 35. Here, the stop position is a position where the slider 28 contacts the stopper 41 (see FIG. 5) or a position where the slider 28 contacts the stopper 42.

The hydraulic control valve 44 is a spring return type 3-port 2-position electromagnetic switching valve. The port 45 of the hydraulic control valve 44 is connected to the oil pump 35, the port 46 is connected to the supply passage 34, and the port 47 is connected to the oil pan 36. The hydraulic control valve 44 connects the ports 46 and 47 when the solenoid is demagnetized, and connects the ports 45 and 46 when the solenoid is excited.

The hydraulic oil 33, the supply passage 34, the coil springs 38 and 39, the discharge passage 43 and the hydraulic control valve 44 constitute a slider drive mechanism M1 for moving the slider 28 along the axes L1 and L2. There is. Also,
Outer camshaft 14, inner camshaft 17, timing pulley 22, slider 28, and slider drive mechanism M
1 constitutes a cam angle adjusting device.

Next, the operation and effect of this embodiment will be described. FIG. 1 shows the state of the cam angle adjusting device when the solenoid of the hydraulic control valve 44 is demagnetized. In this state, the ports 46 and 47 are connected and the port 4
The communication between 5 and 46 is cut off. Therefore, the hydraulic oil 33 from the oil pump 35 is not supplied to the pressure chamber 32 side via the supply passage 34, and the hydraulic oil 33 in the pressure chamber 32 passes through the supply passage 34 and the hydraulic control valve 44 to the oil pan. It is possible to flow to 36. Therefore, the hydraulic oil 33
Of the stopper 4 is urged to the left by the coil springs 38 and 39 with almost no hydraulic pressure applied thereto.
It is pressed against 1 and stopped.

On the other hand, during operation of the engine 1, the rotation of the crankshaft is transmitted to the timing pulley 22 via the timing belt 23, and the pulley 22 slides on the pulley 28.
Rotates together with. The rotation of the slider 28 is transmitted to the second cam 19 via the case 24 splined to the outside thereof and the inner shaft main body 18 fastened to the case 24 by the bolt 25 and the pin 26. Also,
The rotation of the slider 28 is transmitted to the first cam 16 via the outer shaft body 15 spline-coupled to the inside thereof.

At this time, the first cam 16 and the second cam 19 overlap each other as shown in FIG. 4 (a), and the intake valve 6 is lifted according to the characteristic line L3 in FIG. As a result, the intake valve 6 starts to lift when the crank angle is θ2,
The lift ends when θ5 is reached. The cam angle Δθ is a relatively small value (Δθa). At this time, the intake valve 6 opens the intake port 4 for a relatively short period.

When the operating state of the engine 1 changes from the state shown in FIG. 1 and the solenoid of the hydraulic control valve 44 is excited, the ports 45 and 46 are connected to each other and the ports 46 and 47 are disconnected from each other. Therefore, the hydraulic oil 33 discharged from the oil pump 35 is supplied to the pressure chamber 32 via the supply passage 34. When the hydraulic pressure applied to the slider 28 by this supply overcomes the urging force of the coil springs 38 and 39,
By the action of the helical splines 15a, 28a, 24b, 28b, the slider 28 rotating integrally with the timing pulley 22 moves to the right. By the movement accompanied by this rotation, a twisting force is applied to each of the case 24 and the outer camshaft 14, and the outer camshaft 14 and the inner camshaft 17 are referenced with respect to the timing pulley 22.
And rotate relative to each other in opposite directions. This relative rotation is
It is stopped when the slider 28 is pressed against the stopper 42.

At this time, the first cam 16 and the second cam 19 which have been overlapped with each other so far are displaced in the rotational direction as shown in FIG. 4 (b). Then, the intake valve 6 has half of the lift portion 16 b of the first cam 16 and the lift portion 1 of the second cam 19.
Lifted by half of 9b.

Here, in FIG. 5, the relationship between the crank angle and the valve lift amount when the intake valve 6 is lifted only by the first cam 16 is shown by a characteristic line L4, and the intake valve 6 by only the second cam 19 is shown. A characteristic line L5 shows the relationship between the crank angle and the valve lift amount when the valve is lifted. According to the characteristic line L4, the intake valve 6 starts and ends the lift earlier than when the characteristic line L3 is followed. The intake valve 6 starts to lift when the crank angle is θ1,
The lift ends when θ4 is reached. On the contrary, when the characteristic line L5 is followed, the intake valve 6 starts and ends the lift later than when the characteristic line L3 is followed. The intake valve 6 starts the lift when the crank angle is θ3, and ends the lift when the crank angle is θ6.

The intake valve 6 is lifted according to a characteristic line L6 which is a combination of the characteristic lines L4 and L5. Characteristic line L6
Indicates that the first half of the characteristic line L4 and the second half of the characteristic line L5 are connected. Both cams 16 and 19 have the same shape, and the tips of the lift portions 16b and 19b that are involved in the lift of the intake valve 6 are formed into curved surfaces with large radii of curvature centering on the axes L1 and L2. From that,
The connecting portion of the characteristic lines L4 and L5 is substantially linear with little unevenness. According to the characteristic line L6, the intake valve 6 starts the lift when the crank angle is θ1, and ends the lift when the crank angle is θ6. The cam angle at this time is Δθb, which is a value larger than Δθa. Therefore, the intake valve 6 opens the intake port 4 for a long period.

When shifting from this state to the state shown in FIG. 1, the reverse operation is performed. That is, the hydraulic control valve 44
The solenoid is demagnetized, the ports 45 and 46 are connected, and the ports 46 and 47 are disconnected. Therefore, the supply of the hydraulic oil 33 to the pressure chamber 32 side by the oil pump 35 is stopped, and the hydraulic oil 33 in the pressure chamber 32 is returned to the oil pan 36 through the hydraulic control valve 44. Then, the hydraulic pressure applied to the slider 28 suddenly decreases, and the slider 28 is biased to the left by the coil springs 38 and 39. As a result, a twisting force is applied to the case 24 and the outer camshaft 14, and the inner camshaft 17 and the outer camshaft 14 rotate relative to each other. This relative rotation is stopped when the slider 28 is pressed against the stopper 41. And the first cam 1
6 and the second cam 19 overlap each other as shown in FIG. 4A, and lift the intake valve 6 according to the characteristic line L3.

As described above, in this embodiment, the timing pulley 2 is operated during the operation of the engine 1 including the adjustment of the cam angle Δθ.
The outer cam shaft 14 and the inner cam shaft 17 are directly driven by a slider 28 that rotates integrally with the shaft 2.
Therefore, backlash occurs before the rotation of the timing pulley 22 reaches the first cam 16 and the second cam 19 between the helical splines 15a and 28a on the inner peripheral side of the slider 28 and on the outer peripheral side. There are two places, one between the splines 24b and 28b. In other words, in the prior art, there are four locations where backlash occurs in the rotational force transmission path, whereas in the present embodiment this is half that. As a result, the deviation of the actual cam angle with respect to the target cam angle Δθ can be made smaller than in the prior art.
Then, it is possible to suppress abnormal noise and wear of the gear teeth (splines). (Second Embodiment) Next, a second embodiment of the first and second inventions will be described with reference to FIGS.

The second embodiment is greatly different from the first embodiment in that the cam angle adjusting device is also applied to a valve operating mechanism for driving the exhaust valve 52. In the present embodiment, the same members as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and different points will be mainly described.

As shown in FIG. 8, the cylinder head 2 is formed with an exhaust port 51 which communicates with the combustion chamber 3 for each cylinder. An exhaust valve 52 including a stem portion 52a and an umbrella portion 52b is attached to the cylinder head 2. The exhaust port 51 is closed when each exhaust valve 52 moves upward and the umbrella portion 52b comes into contact with the valve seat 53, and each exhaust valve 52 moves downward so that the umbrella portion 52b moves to the valve seat 5.
It is opened when it is separated from 3.

A valve lifter 56 having a shim 55 is inserted into the guide hole 54 of the cylinder head 2, and the upper end surface of each stem portion 52a is in contact with the inner wall surface of the valve lifter 56.
A valve spring retainer 58 is attached to the upper end of each stem portion 52a via a cotter 57. A valve spring 59 is interposed between each retainer 58 and the support surface 2b in the cylinder head 2.
As a result, the exhaust valve 52 is urged upward in the direction of closing the exhaust port 51.

A mechanism for opening and closing each exhaust port 51 by periodically pushing down (lifting) each exhaust valve 52 against the urging force of the valve spring 59 is provided above the valve lifter 56. Has been.

As shown in FIG. 9, an outer camshaft 61 is rotatably supported on the cylinder head 2. The outer cam shaft 61 includes an outer shaft body 62 having a substantially cylindrical shape. In the outer shaft main body 62, a first cam 63 is integrally rotatably formed at a position corresponding to each exhaust valve 52. The outer shaft body 62 and the first cam 63 have basically the same configuration as the outer shaft body 15 and the first cam 16 in the first embodiment.

An inner camshaft 64 having a rod-shaped inner shaft body 65 is inserted into the outer shaft body 62. A second cam 66 is integrally rotatably attached to the inner shaft body 65 at a position corresponding to each exhaust valve 52. The inner shaft body 65 and the second cam 66 have basically the same structure as the inner shaft body 18 and the second cam 19 in the first embodiment.

However, a dedicated mechanism for adjusting the cam angle Δθ as described in the first embodiment is not provided at each left end portion of the outer shaft body 62 and the inner shaft body 65. That is, the timing pulley 22, the slider 28, the case 24, the supply passage 34, the discharge passage 43, etc. in the first embodiment are not provided.

The engine 1 is provided with a transmission mechanism for transmitting each rotation of the outer camshaft 14 and the inner camshaft 17 to the outer camshaft 61 and the inner camshaft 64. An outer drive gear 67 is integrally rotatably attached to the right end of the outer shaft main body 15, and an inner drive gear 68 is integrally rotatably attached to the right end of the inner shaft main body 18. Similarly, the outer driven gear 69 is integrally rotatably attached to the right end of the outer shaft main body 62, and the inner driven gear 70 is integrally rotatably attached to the right end of the inner shaft main body 65. And
The outer drive gear 67 and the outer driven gear 69 mesh with each other, and the inner drive gear 68 and the inner driven gear 70 mesh with each other.

As shown in FIG. 10, on the left side surface of the inner driven gear 70, a pair of arcuate concave portions 71a, 71b and a pair of protrusions 7 are provided at symmetrical positions about the axis L7.
2a and 72b are formed. Each recess 71a, 71
The coil springs 73a, 7 as biasing members are provided in b.
About half of the right side of 3b is accommodated, and one end of each is locked to the protrusions 72a and 72b. In the outer driven gear 69, the recesses 71a, 71b and the protrusions 72a, 72b
Arc-shaped long holes 74a, 7
4b is transparently provided. When both driven gears 69 and 70 are attached to both shaft main bodies 62 and 65, each recess 7
Coil springs 73a exposed from 1a and 71b,
About half of the left side of 73b is accommodated in the long holes 74a and 74b, and the free ends of the holes are brought into contact with the inner walls of the long holes 74a and 74b. These coil springs 73a, 7
3b, the outer driven gear 69 and the inner driven gear 70
Are urged to rotate in directions opposite to each other.

Next, the operation and effect of this embodiment constructed as described above will be described. During the operation of the engine 1 including the adjustment of the cam angle Δθ, the rotation of the outer shaft body 15 is transmitted to the outer shaft body 62 via the outer drive gear 67 and the outer driven gear 69. This transmission causes the outer shaft body 62 to rotate integrally with the first cam 63. Similarly, rotation of the inner shaft body 18 causes the inner drive gear 6 to rotate.
8 and the inner driven gear 70, the inner shaft main body 65
Be transmitted to. This transmission causes the inner shaft body 65 to rotate integrally with the second cam 66. In this way, the rotational force is transmitted between the outer camshafts 14 and 61, and the rotational force is transmitted between the inner camshafts 17 and 64. Therefore,
When the engine 1 is operating, the cams 16, 19 on the intake valve 6 side
When the cam angle Δθ is adjusted, the cam angles Δθ of the cams 63 and 66 are also adjusted on the exhaust valve 52 side.

Further, in this embodiment, the coil springs 73a, 7b are provided between the outer driven gear 69 and the inner driven gear 70.
3b is provided, and both driven gears 69 and 70 are urged to rotate in opposite directions, as indicated by arrows A and B in FIG. The rotational urging force applied to the outer driven gear 69 is transmitted to the outer drive gear 67, and the rotational urging force applied to the inner driven gear 70 is transmitted to the inner drive gear 68. The direction of the rotational biasing force is reversed during the transmission of these. Therefore, the outer drive gear 67 is applied with the rotational biasing force in the direction indicated by the arrow C, and the inner drive gear 68 is applied with the rotational biasing force in the direction indicated by the arrow D. Furthermore, the direction (arrow C direction) of the rotational biasing force applied from the helical spline 15a on the outer periphery of the outer camshaft 14 to the helical spline 28a on the inner periphery of the slider 28, and the inner camshaft 17 (case 2
The direction (direction of arrow D) of the rotational urging force applied to the helical spline 28b on the outer periphery of the slider 28 from the helical spline 24b of 4) is opposite to each other.

Therefore, the backlash is generated at the spline connecting portion between the slider 28 and the case 24, the spline connecting portion between the slider 28 and the outer camshaft 14, the outer drive gear 67 and the outer driven gear 69. There are four possible positions, the meshing part and the meshing parts of the inner drive gear 68 and the inner driven gear 70.
Backlash at these points is canceled by the rotational biasing force of the coil springs 73a and 73b.

As described above, in the second embodiment, in addition to the operation and effect of the first embodiment, the cams on both the intake valve 6 side and the exhaust valve 52 side are driven by one slider 28 and one slider drive mechanism M1. The angle Δθ can be adjusted. Therefore, as compared with the case where the slider 28 and the slider driving mechanism M1 are provided on the valves 6 and 52, respectively, the manufacturing cost can be reduced and the cam angle adjusting device, and thus the engine 1, can be reduced in weight.
In addition, by a set of coil springs 73a, 73b,
From the timing pulley 22 to the cams 16, 19, 63, 66
It is possible to suppress the occurrence of backlash in the rotational force transmission path up to. (Third Embodiment) Next, a third embodiment of the first and second inventions will be described with reference to FIGS. Third
The embodiment is greatly different from the second embodiment in that the outer drive gear 67 is engaged with the inner driven gear 70 and the inner drive gear 68 is engaged with the outer driven gear 69 as shown in FIG. In the present embodiment, the same members as those in the second embodiment are designated by the same reference numerals, and the description thereof will be omitted. Differences will be mainly described.

As shown in FIG. 12, the outer shaft body 6
A flange 75 having a pair of screw holes 76a and 76b is formed on the outer periphery of the right end portion of 2. The right end portion of the inner shaft body 65 is fitted in the square hole 77 of the inner driven gear 70. A pair of arcuate elongated holes 78a, 78b are provided through the inner driven gear 70 at symmetrical positions about the square hole 77. The outer driven gear 6 is provided on the right side of the inner driven gear 70.
9 are arranged. On the left side surface of the outer driven gear 69, a pair of connecting pins (only one is shown in FIG. 12) 79 at positions corresponding to the screw holes 76a and 76b.
Is projected. Outer driven gear 69 and both connecting pins 7
9, a pair of bolt insertion holes 81a,
81b is provided. These bolt insertion holes 81
A and 81b may be screw holes. Then, the two connecting pins 79 are inserted into the corresponding long holes 78a, 78b and abut against the flange 75, and the bolts 82a, 82b inserted in the respective bolt insertion holes 81a, 81b are screw holes 76a, 76.
It is screwed into b. In this way, the inner driven gear 7
An outer driven gear 69 is attached to the flange 75 (outer camshaft 61) with 0 interposed therebetween.

Although not shown in FIG. 12, both the driven gears 69 and 70 are pivotally mounted in opposite directions between the outer driven gear 69 and the inner driven gear 70, as in the second embodiment. A coil spring for biasing is attached.

Therefore, also in this embodiment, as in the second embodiment, the cam angle Δθ on both the intake valve 6 side and the exhaust valve 52 side is set by one slider 28 and one slider drive mechanism M1. Can be adjusted.
Also, from the timing pulley 22 to the cams 16, 19, 6
It is possible to suppress the occurrence of backlash in the rotational force transmission path up to 3,66.

The present invention can be embodied in another embodiment shown below. (1) In the second and third embodiments, both drive gears 67 and 68 are provided at the right end portions of both shaft bodies 15 and 18, but these drive gears 67 and 68 are provided to the shaft bodies 15 and 18. It may be attached separately to the right end and the left end. In this case, both driven gears 69 and 70 are attached separately to the right end and the left end of the shaft bodies 62 and 65.

For example, as shown in FIG. 13, the inner drive gear 67 is attached to the left end portion of the inner shaft body 18 while the outer drive gear 67 is attached to the right end portion of the outer shaft body 15. The inner driven gear 70 is the inner shaft body 65.
The outer driven gear 69 may be attached to the left end of the outer shaft main body 62 while being attached to the right end of the outer shaft main body 62. In this case, a flange 83 is provided on the right end portion of the outer shaft main body 62, and a coil spring for urging the driven gears 69 and 70 to rotate in opposite directions between the flange 83 and the inner driven gear 70. 73a and 73b are arranged. Even in this case, the same operation and effect as those of the second and third embodiments can be obtained.

(2) The cam angle adjusting device of the first invention can be applied to other than the valve mechanism of the internal combustion engine. (3) In the first to third embodiments, the timing pulley 22 is provided on the outer periphery of the outer shaft main body 15 on the intake valve 6 side, and the slider 28 is interposed between the shaft main bodies 15 and 18, but these members are used. The (timing pulley 22, slider 28) is connected to the shaft main body 62 on the exhaust valve 52 side,
65 may be provided only, or both the shaft bodies 15, 18, 6 on both the intake valve 6 side and the exhaust valve 52 side.
2, 65 may be provided.

(4) By appropriately changing the inclination angles of the helical splines 15a, 28a, 24b, 28b with respect to the axis lines L1, L2, the characteristic of the valve lift amount with respect to the crank angle in FIG. 5 can be changed.

(5) A sprocket may be used as the rotating member instead of the timing pulley 22 in the first to third embodiments, and a timing chain may be used instead of the timing belt 23.

(6) The first and second inventions can also be embodied in a cam angle adjusting device for holding the slider 28 in FIG. 1 at an intermediate position between the stoppers 41 and 42. In addition, in this specification, the member which concerns on the structure of invention shall be defined as follows.

The urging member (a) means a member for urging the outer driven gear 69 and the inner driven gear 70 to rotate in opposite directions. In addition to the coil springs 73a and 73b,
Not only springs such as plate springs (leaf springs), spiral springs (spiral springs) and bar springs,
Sponge, synthetic rubber, natural rubber, elastomers and other polymeric elastic materials are included.

[0073]

As described above in detail, in the first invention, the slider having the helical splines on the inner and outer circumferences is interposed between the outer shaft body and the inner shaft body, and the sliders are mounted on both shaft bodies by the helical splines. The splines are combined. Further, the slider driving mechanism moves the slider along the axis to change the rotational phase of both cam shafts relative to the rotating member to adjust the cam angle. Therefore, it is possible to reduce the number of locations where backlash occurs in the rotational force transmission path from the rotating member to the cam, and to reduce the deviation amount of the actual cam angle from the target cam angle.

In the second invention, the outer drive gear and the inner drive gear are attached to the outer shaft body and the inner shaft body corresponding to one valve, and the outer driven gear is attached to the outer shaft body and the inner shaft body corresponding to the other valve. And the inner driven gear is attached. Then, both driven gears are meshed with both drive gears, and the outer driven gear and the inner driven gear are urged to rotate in opposite directions by the urging member. Therefore, in addition to the effect of the first invention,
With one slider drive mechanism, the cam angle of the cam for driving the intake valve and the exhaust valve of the internal combustion engine can be adjusted, and the manufacturing cost and weight can be reduced. Further, it is possible to suppress the occurrence of backlash in the rotational force transmission path from the rotating member to each cam for driving the intake / exhaust valve.

[Brief description of drawings]

FIG. 1 is a sectional view of a cam angle adjusting device in a first embodiment embodying the first invention.

FIG. 2 is a partial perspective view of an outer cam shaft and an inner cam shaft in the first embodiment.

FIG. 3 is a partially exploded perspective view of an outer cam shaft, an inner shaft body, and a second cam in the first embodiment.

FIG. 4A is a cross-sectional view of the outer cam shaft and the inner cam shaft when the first cam and the second cam overlap with each other in the first embodiment, and FIG. FIG. 3 is a cross-sectional view of both cam shafts when they are opened.

FIG. 5 is a characteristic diagram showing a correspondence relationship between a crank angle and a valve lift amount in the first embodiment.

FIG. 6 is a partial cross-sectional view of an intake valve and its peripheral portion in the first embodiment.

FIG. 7 is an explanatory view schematically showing the cam angle adjusting device of the first embodiment.

FIG. 8 is a partial cross-sectional view of an intake valve and its peripheral portion in a second embodiment in which the first and second inventions are embodied.

FIG. 9 is an explanatory view schematically showing a cam angle adjusting device of a second embodiment.

FIG. 10 is a perspective view showing an outer driven gear and an inner driven gear of a second embodiment.

FIG. 11 is an explanatory view schematically showing a cam angle adjusting device according to a third embodiment that embodies the first and second inventions.

FIG. 12 is an exploded perspective view showing an outer driven gear, an inner driven gear and the like in a third embodiment.

FIG. 13 is an explanatory view schematically showing another embodiment of the cam angle adjusting device.

FIG. 14 is a partially developed view showing the notch and the slider in the prior art in a developed state.

FIG. 15 is a sectional view showing a conventional technique.

[Description of Reference Signs] 1 ... Engine as internal combustion engine, 6 ... Intake valve as driven member, 14, 61 ... Outer camshaft, 15, 6
2 ... Outer shaft body, 16, 63 ... First cam, 17,
64 ... Inner cam shaft, 18, 65 ... Inner shaft main body, 19, 66 ... Second cam, 22 ... Timing pulley as rotating member, 28 ... Slider, 28a, 28b ... Helical spline, 52 ... Exhaust valve as driven member , 67 ... Outer drive gear, 68 ... Inner drive gear, 69 ...
Outer driven gear, 70 ... Inner driven gear, 73a, 73b ...
Coil spring as biasing member, Δθ ... cam angle, L
1, L2 ... Axis, M1 ... Slider drive mechanism.

Claims (2)

[Claims] 1. A cylindrical outer shaft main body, and an outer cam shaft that is integrally rotatably provided on the outer shaft main body and that has a first cam for periodically operating a driven member by its rotational movement. The inner shaft body inserted into the outer camshaft and the inner shaft body are integrally rotatably provided.
And an inner cam shaft having a second cam for periodically operating the driven member together with the first cam by the rotational movement thereof, a rotating member rotatably provided on an outer periphery of the outer shaft body, and the outer side The helical spline is interposed between the shaft main body and the inner shaft main body, is attached to the rotating member so as to be integrally rotatable, and is capable of reciprocating in the axial direction of the both cam shafts, and has a helical spline that intersects with the axial line inside itself. A slider having a circumference and an outer circumference and splined to the outer shaft body and the inner shaft body by their helical splines; a first cam from the start of the operation of the driven member to the end of the operation; In order to adjust the cam angle, which is the rotation angle of the second cam, the slider is moved along the axis to move the rotating portion. Cam angle adjusting device that includes a slider drive mechanism for changing the rotational phases of both the camshaft relative. 2. The driven member is an intake valve and an exhaust valve of an internal combustion engine, a pair of the outer cam shaft and the inner cam shaft is provided corresponding to both valves, and each of the slider, the rotating member and the slider drive mechanism. Is provided corresponding to one valve, the outer drive gear is attached to the outer shaft body corresponding to the one valve, and the inner drive gear is attached to the inner shaft body connected to the outer shaft body by a slider, The outer driven gear is attached to the outer shaft body corresponding to the other valve, the inner driven gear is attached to the inner shaft body corresponding to the same valve, both driven gears mesh with both drive gears, and the outer driven gear and inner driven gear The cam angle adjusting device according to claim 1, further comprising a biasing member that biases the gears to rotate in opposite directions.