JPH06221122A - Valve timing control device for engine - Google Patents

Abstract

PURPOSE:To suppress abrasion of a cam regulation part and generation of noises by reducing thrust force applied to a cam shaft. CONSTITUTION:A spline connection part of a cam shaft 6 and a rotary driving member 21 is composed of helical splines 31, 32. In respect to inclination directions of spline grooves of the helical splines 31, 32, the direction of thrust force F2 is opposed to the direction of thrust force F1, the force F2 being generated between the rotary driving member 21 and the cam shaft 6 by a torque of the rotary driving member 21 at the spline connection part, and the force F1 being generated on the cam shaft 6 by the contact pressure between rotary cams 7, 8 and oscillating cams 4, 5. Thrust force F0 which is generated on the cam shaft 6 as resultant force of the thrust force F1 and the thrust force F2 is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a rotary cam provided on a cam shaft and a swing cam that slidably contacts the swing cam and swings the cam shaft in the axial direction to adjust the valve timing. The present invention relates to an engine valve timing control device that is variable.

[0002]

2. Description of the Related Art Various methods for varying the valve timing of an engine have been proposed in the past, and one of them has been proposed to be rotated synchronously by the engine, as disclosed in, for example, Japanese Patent Publication No. 58-38602. A tapered rotary cam formed on the cam shaft, and a swing cam that is arranged between the rotary cam and the valve and swings with the rotation of the rotary cam to open and close the valve. In a so-called rocking cam type valve mechanism, by moving the cam shaft in the axial direction according to the operating state of the engine, the relative position of the rotary cam and the rocking cam in the axial direction is changed, and thus the valve timing is adjusted. A system has been proposed in which the valve lift and the valve lift can be varied at the same time.

[0003]

By the way, in such a valve timing control device, normally, the biasing force of a biasing means such as a spring for constantly biasing the cam shaft to one side in the axial direction and the biasing force. The camshaft is moved in the axial direction by an appropriate moving means that generates an operation force in the direction opposite to, and the valve timing and the like are changed and adjusted. However, in this case, the problem is the camshaft. It is the thrust force generated in the.

That is, since both the rotating cam and the swinging cam, which are in sliding contact with each other, have tapered cam surfaces,
When the oscillating cam receives the spring force of the valve spring, contact pressure acts on the sliding contact surface between this and the rotating cam, and as a result, a thrust force of a magnitude corresponding to the inclination of the cam surface is generated on the cam shaft. However, this thrust force is not constant and changes with changes in valve lift (i.e., the contact pressure increases when the valve lift is large, so the thrust force also increases, and the contact pressure decreases when the valve lifts small. Therefore, the thrust force also becomes smaller). In this case, for example, the urging direction of the urging means and the acting direction of the thrust force are set to be the same direction, and the operating force of the moving means is released to move the cam shaft to the urging force of the urging means. When the cam shaft returns to its original position and when the camshaft is in a rotation phase corresponding to a large valve lift (that is, when a large thrust force is generated)
, The camshaft is moved by the resultant force of the urging force of the urging means and the thrust force, so that the rotary cam causes a relatively large impact on the restricting portion that restricts the moving range of the camshaft. There is a possibility that a collision may occur with force, which may cause problems such as promoting wear of the restriction portion or generating noise.

Further, in the above case, when the cam shaft is moved from the small lift side to the large lift side by the moving means, the moving means applies the thrust force in addition to the operation force capable of counteracting the biasing force. It is necessary to have an operating force capable of countering the above, and there is also a problem that the moving means becomes large and the responsiveness of the operation deteriorates accordingly.

Therefore, the present invention reduces the thrust force acting on the cam shaft to suppress the abrasion or noise of the cam shaft restricting portion, and improves the responsiveness at the time of adjusting the valve timing. It is intended to provide a valve timing control device for an engine capable of suppressing the wear of the rotary drive member and the swing cam due to the above.

[0007]

As a concrete means for solving such a problem in the present invention, in the invention as set forth in claim 1, a rotary cam having a tapered cam surface is provided, and the shaft is attached to the bearing member. Cam shaft that is movably supported in the direction, and the movement range is restricted by the end surface of the rotary cam contacting a cam shaft restricting portion provided on the supporting member side; and the cam shaft with respect to the supporting member. An oscillating cam that is swingably attached to an oscillating cam bearing shaft that is supported in parallel, and that is slidably contacted with the rotating cam and swings in conjunction with the rotation of the rotating cam to lift the valve, The cam shaft is rotatably supported with respect to the support member in a state in which the movement in the axial direction is restricted, is rotated by the engine torque, and is spline-coupled to one end of the cam shaft. A rotary drive member that rolls, a biasing means that constantly biases the cam shaft to one side in the axial direction, and a second end side in the axial direction of the cam shaft against the biasing force of the biasing means. In a valve timing control device for an engine including a cam shaft moving means for moving to, a spline coupling portion between the cam shaft and the rotation driving member is configured by a helical spline, and an inclination direction of a spline groove of the helical spline is The direction of the thrust force generated between the rotary drive member and the cam shaft by the rotational force of the rotary drive member in the spline coupling portion, and the contact pressure between the rotary cam and the swing cam, the cam The feature is that the thrust force generated on the shaft is set to be opposite to the acting direction.

According to a second aspect of the present invention, in the engine valve timing control device according to the first aspect, a gear portion formed of a helical gear is formed on the rotary drive member, and a drive gear is meshed with the gear portion. Along with the inclination direction of the teeth of the helical gear, the direction of the thrust force that acts on the gear portion in response to the rotational force from the drive gear and the thrust force generated at the spline joint portion between the rotary drive member and the cam shaft are The feature is that the action direction is set to be the same direction.

According to a third aspect of the invention, in the engine valve timing control device according to the first aspect, the oscillating cam is provided with an urging force receiving portion, and the urging force receiving portion is provided with an oscillating cam urging means. The oscillating cam urging means is arranged to urge the oscillating cam to rotate in a direction in which the oscillating cam is slidably contacted with the rotating cam, while the urging force receiving portion slidably contacts the oscillating cam urging means. The surface is tilted in a direction opposite to the tilt direction of the cam surface of the swing cam.

[0010]

With each of the inventions of the present application, the following effects can be obtained by adopting such a configuration.

According to the first aspect of the present invention, the thrust force generated by the rotational force of the rotary drive member and the inclination of the spline groove at the spline coupling portion between the cam shaft and the rotary drive member, and the rotary cam portion of the cam shaft. Since the thrust force generated by the sliding contact with the swing cam acts in the opposite direction, the combined thrust force that appears on the cam shaft as the total force of the two thrust forces in these different directions is the thrust force at the spline joint. It is small compared to the case where does not occur. Therefore, even when the thrust force acting on the cam shaft and the urging force of the urging means simultaneously act to move the cam shaft to the cam shaft restricting portion, the moving force itself is small, so that the rotating cam and the cam The impact force at the time of a collision with the shaft restricting portion is reduced.

According to the second aspect of the invention, the following action is obtained in addition to the action described above. That is, when a thrust force is generated at the spline coupling portion between the cam shaft and the rotary drive member, the thrust force is not reflected on the restricting member supported by the supporting member with its axial movement restricted. As a force, a contact pressure is generated between the bearing member and the bearing member. On the other hand, a thrust force also acts on the meshing portion between the rotary drive member and the drive gear due to the inclination of the teeth of the helical gear and the action of this thrust force. The direction is the same as the acting direction of the thrust force generated in the spline coupling portion (in other words, the direction opposite to the reaction force). Therefore, the contact pressure can be reduced by the thrust force acting between the rotary drive member and the drive gear.

According to the third aspect of the invention, the following action is obtained in addition to the action described above. That is, since the sliding contact surface of the urging force receiving portion formed on the oscillating cam with respect to the oscillating cam urging means is set in the direction opposite to the inclination direction of the cam surface of the oscillating cam, The thrust force generated by the sliding contact with the rotating cam and acting in the direction to bring the swing cam into contact with the support member side, and the thrust force acting on the swing cam by the biasing force of the swing cam biasing means. In the opposite direction, the contact pressure acting on the bearing member is reduced accordingly.

[0014]

Therefore, according to the engine valve timing control device of each invention of the present application, the thrust force generated at the spline coupling portion between the cam shaft and the rotary drive member is generated by the sliding contact between the rotary cam and the swing cam. The thrust force that appears on the cam shaft as a resultant force is reduced by acting in a direction that reduces the thrust force that occurs, and the impact force between the rotating cam and the cam shaft regulating portion when the cam shaft moves is reduced. Therefore, wear of the camshaft restricting member is suppressed, unpleasant noise is reduced, and durability and reliability of the valve train can be expected to be improved.

In addition, in the engine valve timing control device according to the second aspect of the invention, in addition to the above-described basic effects, the thrust force generated between the rotary drive member and the drive gear causes the rotary drive member to rotate. The contact pressure with the restriction portion is made small, and the effect of suppressing wear of the restriction portion and the like is obtained as much as possible.

Further, in the engine valve timing control device according to a third aspect of the present invention, in addition to the above basic effects, the contact pressure between the rocking cam and the restricting portion is made small so that the restricting portion is reduced. It is possible to obtain the effect that abrasion such as the above is suppressed as much as possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The valve timing control device for an engine according to the present invention will be described below in detail with reference to the embodiments. FIGS. 1 and 2 show the valve timing control device according to the present invention for the intake side movement of a multi-cylinder engine. A valve mechanism is shown, and in each of the drawings, reference numeral 1 is an intake valve (corresponding to a valve in the claims) in which two valves are arranged for each cylinder. 1, 1 are normally urged in the valve closing direction by valve springs 2, 2 and a valve tappet 3 is attached to the upper end thereof. The valve tappets 3 of the intake valves 1 and 1 are slidably supported by a supporting member 10 fixedly arranged on the cylinder head 16, and a cam mechanism P to be described later attached to the supporting member 10. It is driven to open and close.

The cam mechanism P has a cam shaft 6 in which a first rotating cam 7 and a second rotating cam 8 each having a tapered cam surface for each cylinder are axially adjacent to each other. The cam shaft 6 is mounted on the bearing member 10 with the rotary cams 7 and 8 positioned between the second bearing portion 36 and the third bearing portion 37 of the bearing member 10. It is supported so that it can slide in any direction.

Further, the cam shaft 6 has an external tooth helical spline 31 formed at one end 6a thereof, and the one end 6a is axially movable with respect to the first bearing portion 35 of the bearing member 10. It is meshed with an internal tooth helical spline 32 formed on an intake side cam gear 21 (corresponding to a rotary drive member in the claims) rotatably supported in a regulated state. Further, the intake-side cam gear 21 is composed of a helical gear, which is also composed of a helical gear and which is rotated by the engine, on the exhaust-side cam gear 22 (corresponding to a drive gear in claims).
Is engaged with. Therefore, the cam shaft 6 is rotationally driven by the exhaust side cam gear 22 via the intake side cam gear 21.

On the other hand, the other end (not shown) of the cam shaft 6 is provided with a biasing means (not shown) such as a spring for constantly biasing the cam shaft 6 in a direction of an arrow R with a predetermined biasing force. Cam shaft 6
Is arranged in the direction of arrow L against the biasing force of the biasing means (not shown).

On the other hand, the camshaft 6 and the intake valves 1, 1
An oscillating cam support shaft 11 is arranged between the valve tappets 3, 3 in parallel with the cam shaft 6.
Then, the first swing cam 4 is attached to the swing cam support shaft 11.
And the second swing cam 5 are the rotary cams 7 of the cam shaft 6,
8 and the valve tappets 3, 3 of the intake valves 1, 1 are slidably attached. These rocking cams 4, 5
Is a first cam surface 41, 51 slidably contacting the top surface of the valve tappet 3, a tapered second cam surface 42, 52 slidably contacting each of the rotary cams 7, 8, and a second cam surface 42, Biasing force receiving portions 43, 5 slidingly contacting the rocking cam biasing means 12 for pressing the rotary cam 52 with the predetermined pressing force toward the rotary cams 7, 8 side.
3 and swings in the direction of arrow c-d as the rotary cams 7, 8 rotate in the direction of arrow a, and the intake valves 1,
1 is opened and closed.

In the valve timing control device having the cam mechanism P having such a structure, the intake side cam gear 21 is rotationally driven through the exhaust side cam gear 22 so that the cam shaft 6 rotates synchronously with the engine. The intake valves 1, 1 are opened and closed by the rotary cams 7, 8 and the swing cams 4, 5 sliding on the rotary cams 7, 8. Then, the camshaft moving means is operated in accordance with the operating state of the engine to operate the camshaft 6.
Is moved in the axial direction to change the relative sliding contact position between the rotary cams 7 and 8 and the swing cams 4 and 5 to change and set the valve timing and the valve lift amount, and the cam shaft 6 The movement of the rotary shaft changes the rotational phases of the camshaft 6 and the crankshaft (not shown) according to the inclination angles of the helical splines 31 and 32.

The movement control of the camshaft 6 (that is, the control for changing the valve timing, etc.) is performed according to the operating state of the engine as described above.
When the engine is operating at high speed and under high load, the camshaft moving means moves the camshaft 6 in the direction of arrow L as shown in FIG. 2 in order to increase the valve lift and advance the valve timing. At the time of low load operation, the arrow R is applied by the urging force of the urging means to the camshaft 6 in order to reduce the valve lift and delay the valve timing.
It is to move in the direction.

In the camshaft 6, the end surface 8a of the second rotary cam 8 in the direction of arrow R is the end surface 37a of the third support portion 37 of the support member 10 (corresponding to the restricting portion in the claims). The end surface 7a of the first rotating cam 7 in the direction of the arrow L by contacting the supporting member 10
By contacting the end surface 36a of the second support portion 36, the further movement of the second support portion 36 is restricted. Further, in the rocking cams 4 and 5, the end surface of the spacer 20 adjacent to the second rocking cam 5 contacts the end surface 37a of the third support portion 37 in the arrow R direction, so that the arrow L also moves. In the direction, the end face 4a of the first rocking cam 4 contacts the end face 36a of the second support portion 36, so that the axial movement thereof is restricted. The intake side cam gear 21 has a pair of left and right end faces 21 formed on both sides of the first support portion 35 with the first support portion 35 interposed therebetween.
a and 21b are both end faces 35a and 3 of the first bearing 35, respectively.
By making contact with 5b, its axial movement is restricted.

By the way, when the intake valves 1, 1 are opened and closed by the rotary cams 7, 8 via the swing cams 4, 5,
Since the rotary cams 7, 8 and the swing cams 4, 5 each have a tapered cam surface, the sliding contact portions between the rotary cams 7, 8 and the swing cams 4, 5 are the same. When a predetermined contact pressure is applied by the spring force of each valve spring 2, 2 transmitted from each intake valve 1, 1, the thrust force F _{1 in the} arrow R direction is a component force of the contact pressure in the cam shaft direction. Occurs. The thrust force F ₁ is not always constant, but changes depending on the valve lift amount, and the valve lift amount is large (that is, the rocking cams 4, 5 are high cam height portions of the rotary cams 7, 8). During the rotational phase in sliding contact with each other, and at the same rotational phase, when the rocking cams 4, 5 are in sliding contact with the large diameter side of the rotating cams 7, 8).

Therefore, such a large thrust force F ₁
When acting on the cam shaft 6 as a resultant force of the urging force of the urging means acting in the same direction as this, and moving the cam shaft 6 from the position shown in FIG. At the moving end, the end surface 8a of the second rotary cam 8 is moved to the above-mentioned third end.
As described above, there is a concern that the end surface 37a of the support portion 37 collides with a relatively large impact force, resulting in accelerated wear of the end surface 37a or generation of unpleasant noise. Is.

Therefore, in this embodiment, the cam shaft 6 and the intake side cam gear 21 which are spline-coupled to each other are provided.
In between is due to the inclination of the helical splines 31 and 32 focused on the thrust force F ₂ is generated by the rotating force of the intake side cam gear 21, the thrust force F ₂
To act in a direction opposite to the acting direction of the thrust force F ₁ , thereby reducing the synthetic thrust force F ₀ acting as a part of the driving force for moving the cam shaft 6 in the arrow R direction, Therefore by applying the invention of the present application according to claim 1, wherein in said inclined direction of each helical splines 31 and 32, the direction the thrust force of the thrust force F ₂ F ₁
The opposite direction is set.

By doing so, the arrow R of the camshaft 6
End face 8a of the second rotary cam 8 when moving in the direction
The impact force due to the collision between the end face 37a of the third support portion 37 and the third support portion 37 can be reduced to suppress the wear of the end face 37a or the generation of noise as much as possible, and as a whole, the valve train as a whole. The durability or reliability of can be improved. Further, when the combined thrust force F ₀ acting on the cam shaft 6 becomes smaller in this way, the operating force for moving the cam shaft 6 in the direction of the arrow L by the cam shaft moving means can be made smaller, and the valve is as much. The operation response when the lift is variable is improved, higher engine performance can be obtained, and the camshaft moving means can be downsized.

On the other hand, the thrust force F ₂ is generated at the spline connecting portion between the cam shaft 6 and the intake side cam gear 21, and as a reaction force, one end surface 21b of the intake side cam gear 21 and the first bearing are supported. It is considered that a relatively large contact pressure is generated between the end surface 35b and the one end surface 35b of the portion 35, and in some cases, the end surface 35b is worn away. Therefore, in this embodiment, the invention of claim 2 of the present application is applied, and the inclination of the teeth of the helical gear of the intake side cam gear 21 is changed from the exhaust side cam gear 22 due to the inclination of the helical gear. The thrust force F ₃ generated by the driving force is set to be in the same direction as the thrust force F ₂ . By doing so, as a reaction force of the thrust force F ₂ , the intake cam gear 21 and the first support portion 35 are
Contact pressure acting between the is reduced by the thrust force F _3, are much wear of the end face 35b is suppressed, in which can be improved durability.

Further, the thrust force F is applied to the cam shaft 6.
_{When 1} is generated, as a reaction force thereof, a thrust force F ₄ is generated on the rocking cams 4 and 5 side in a direction to move the rocking cams 4 and 5 to the second bearing portion 36 side. As a result,
Between one end surface 4a of the first swing cam 4 and the end surface 36a of the second support portion 36, and between the end surface 5a of the second swing cam 5 and the other end surface 4b of the first swing cam 4. Therefore, a large contact pressure is generated to promote wear of this portion. For this reason, in this embodiment, the invention according to claim 3 of the present application is applied to form a support portion for the urging force from the oscillating cam urging means 12 formed on each of the oscillating cams 4 and 5. The upper surface of each urging force receiving portion 43, 53 is an inclined surface that is inclined in a direction opposite to the inclination direction of the cam surface of each swing cam 4, 5 and is input to each urging force receiving portion 43, 53. The thrust force F is generated by the urging force from the oscillating cam urging means 12.
A thrust force F ₅ in the opposite direction to ₄ is generated. By doing so, a part of the thrust force F ₄ acting as the contact pressure is subtracted by the thrust force F ₅ , and as a result, the contact pressure is reduced, and the wear as described above is suppressed accordingly. is there.

On the other hand, FIG. 3 shows a part of a valve timing control device according to another embodiment of the present invention.
In this embodiment, the basic structure is the same as that of the above embodiment, and therefore, the same operation and effect can be obtained, but in addition to this, the effect of eliminating the influence of the thrust force F ₁ is eliminated. Is a step further than the case of the above embodiment. That is, in the case of FIG. 3,
A piezo element 18 having a property that the laminated thickness changes due to a change in applied voltage is interposed between the cylinder head 16 and the spring receiver 17, and the applied voltage to the piezo element 18 is changed according to the engine speed. It was done like this. Specifically, in a high engine speed range, a high voltage is applied to increase the thickness of the piezo element 18 to increase the spring force of the valve spring 2. Conversely, in a low engine speed range, a low voltage is applied. The thickness of the piezo element 18 is reduced to reduce the spring force of the valve spring 2.
This voltage control is performed by outputting a control signal from the control unit 25 based on the output signal from the rotation speed sensor 26.

In this way, the spring force of the valve spring 2 is changed according to the engine speed in order to increase the spring force from the viewpoint of suppressing jump or bounce of the intake valve 1 at the time of high rotation. While it is necessary, low-speed rotation without necessity to increase the reduced spring force generation of jump to, therefore, wear countermeasure choice that is set smaller the spring force to reduce the thrust force F ₁ at the time of low rotation This is because it is considered useful in.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of a valve timing control device for an engine according to an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a longitudinal sectional view of a main part of a valve timing control device according to another embodiment of the present invention.

[Explanation of symbols]

1 is an intake valve, 2 is a valve spring, 3 is a valve tappet, 4 is a first swing cam, 5 is a second swing cam, 6 is a cam shaft, 7 is a first rotary cam, 8 is a second rotary cam, Reference numeral 10 is a bearing member, 11 is a swing cam support shaft, 12 is a swing cam biasing means, 16 is a cylinder head, 18 is a piezo element, 20 is a spacer, 21 is an intake side cam gear, 22 is an exhaust side cam gear, and 25 is a A control unit, 26 is a rotation speed sensor, 31 is a helical spline, 32 is a helical spline, 41 is a first cam surface, 42 is a second cam surface, 43 is an urging force receiving portion, 51 is a first cam surface, and 52 is a first cam surface. 2 cam faces, 53
Is a sliding contact surface, and P is a cam mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroshi Enomoto, 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Yasunori Kanda 3-3-1 Shinchu, Fuchu-cho, Aki-gun, Hiroshima Mazda Corporation (72) Inventor Eiichi Yanagida 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (3)

[Claims] 1. A rotary cam having a tapered cam surface, which is axially movably supported by a bearing member, and an end face of the rotary cam contacts a cam shaft restricting portion provided on the bearing member side. A cam shaft whose movement range is regulated by contact with the rocking cam and a rocking cam bearing shaft that is supported in parallel with the cam shaft with respect to the bearing member are swingably attached and slidably contact with the rotary cam. A swing cam that swings in conjunction with the rotation of the rotary cam to lift the valve, and a swing cam that is rotatably supported by the bearing member with its axial movement restricted and is rotated by the engine torque. A rotation drive member that is urged and spline-coupled to one end of the cam shaft to drive the cam shaft in rotation; a biasing means that constantly biases the cam shaft in one axial direction thereof; Is a valve timing control device for an engine, comprising: a camshaft moving means for moving the camshaft to the other end side in the axial direction thereof against the urging force of the urging means. The spline coupling portion is composed of a helical spline, and the inclination direction of the spline groove of the helical spline is generated between the rotary driving member and the cam shaft by the rotational force of the rotary driving member at the spline coupling portion. It is characterized in that the acting direction of the thrust force and the acting direction of the thrust force generated on the cam shaft by the contact pressure between the rotary cam and the swing cam are set to be opposite to each other. Engine valve timing controller. 2. The rotary drive member according to claim 1, wherein the rotary drive member has a gear portion composed of a helical gear, and the drive gear is meshed with the gear portion, and the inclination direction of the teeth of the helical gear is the drive direction. It is set so that the direction of the thrust force acting on the gear portion in response to the rotational force from the gear and the acting direction of the thrust force generated at the spline joint between the rotary drive member and the cam shaft are the same direction. A valve timing control device for an engine. 3. The oscillating cam according to claim 1, wherein an urging force receiving portion is formed on the oscillating cam, and an oscillating cam urging means is disposed on the urging force receiving portion, and the urging force of the oscillating cam urging means is used to provide the urging force receiving portion. The oscillating cam is urged to rotate in the direction of sliding contact with the rotating cam, while the sliding contact surface of the urging force receiving portion with respect to the oscillating cam urging means is set in the inclination direction of the cam surface of the oscillating cam. A valve timing control device for an engine, which is tilted in the opposite direction.