JPH05332105A - Valve timing adjustment device of internal combustion engine - Google Patents

Abstract

PURPOSE:To shorten length in the shaft direction by forming a phase control mechanism of a shaft member of a fixed screw, a nut member screwed on the shaft member and to move in the shaft direction and a rotor only rotationally connected to the nut member and not to move in the shaft direction. CONSTITUTION:A control member 6 is supported by a phase control mechanism 7 and it is adjusted to move in the axial direction of a cam shaft 1. The phase control mechanism 7 has a shaft part 9 fixed on the extension of the cam shaft 1, a ball screw mechanism furnished with a nut part 10 to screw on it and a ball bearing 11. By arranging a rotor 12 loosely engaged with the outside cylindrical surface of the nut part 10 free to move in the shaft direction, rotation is transmitted by engagement of a projected wire 12a and a key groove 10b. As transmission of rotation and a position of driving in the shaft direction on a shaft member of a screw are aggregated on a nut member in this way, length in the shaft direction is significantly shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing adjusting device for changing the opening / closing timing of intake / exhaust valves of an internal combustion engine according to operating conditions.

[0002]

2. Description of the Related Art As a mechanism for adjusting the valve timing of intake and exhaust valves in accordance with the operating conditions of an internal combustion engine, when a camshaft is driven from a crankshaft via a timing belt, chain, gear or the like, It is known that a means for changing the relative phase of the crankshaft and the camshaft is provided in the middle of the driving force transmission path. (See, for example, JP-A-59-87214)

In the above-mentioned conventional apparatus, a sleeve is connected to a timing pulley driven by a timing belt from a crankshaft, and a sleeve connected to a camshaft is rotatably fitted in the sleeve so that the sleeve and the inside of the sleeve are connected to each other. Slits are formed on the circumference of both sleeves in directions intersecting with each other, and at the intersections of these slits, a phase changing member rotatably supported by a ball screw nut is inserted. By rotating the shaft of the ball screw, which does not move in the axial direction, by the electric motor, the phase changing member is moved in the axial direction together with the nut to change the position of the intersection of the slits, and the relative rotation between the inner and outer sleeves is performed. Continuous to the rotation phase of the camshaft with respect to the timing pulley or crankshaft It is adapted to produce a change.

[0004]

In the conventional valve timing adjusting device, the electric motor for imparting rotation to the shaft of the ball screw is arranged on the extension of the shaft of the ball screw. Not only does the amount of protrusion in the axial direction increase, but the nut screwed on the shaft to extract axial reciprocating motion from the rotation of the shaft of the ball screw overlaps with the position where the electric motor rotates the shaft. Since it is not possible to install the valve timing adjustment device on the shaft far away from the electric motor, the overall length of the valve timing adjustment device in the axial direction increases and the size increases, which requires a considerably large space for installation. Therefore, it is a problem when it is installed in a car. In view of the above problems, the present invention is
It is an object of the invention to reduce the axial length of the valve timing adjusting device for an internal combustion engine as compared with the case of the prior art and to improve the mountability by reducing the overhang and the physique of the motor portion. ..

[0005]

As a means for solving the above-mentioned problems, the present invention comprises two rotating members which are formed between a crankshaft and a camshaft of an internal combustion engine and which are coaxially supported. A control member that is arranged between the crankshaft and the camshaft to relatively rotate the two rotating members by moving in the axial direction of the camshaft to change the rotational phase between the crankshaft and the camshaft; In a valve timing adjusting device for an internal combustion engine having a phase control mechanism for moving a member in an axial direction, the phase control mechanism includes a shaft member of a screw fixed in a housing,
A nut member that can be screwed into the shaft member to rotate and can also move in the axial direction; and a rotor that is rotationally driven by a motor and is rotationally connected to the nut member and does not move in the axial direction. There is provided a valve timing adjusting device for an internal combustion engine, comprising:

[0006]

In the valve timing adjusting apparatus for an internal combustion engine according to the present invention, the phase control mechanism for axially moving the control member is screwed to the shaft member of the screw fixed in the housing. Since it is provided with a nut member that can rotate in the axial direction and also can move in the axial direction, and a rotor that is rotationally driven by a motor and is rotationally connected to the nut member and does not move in the axial direction, The nut member has both the function of transmitting rotation on the shaft member and the function of transmitting motion in the axial direction, and a valve according to the related art in which members having these functions are arranged in series in the axial direction of the shaft member. The axial length is significantly reduced compared to the timing adjustment device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical sectional front view showing the overall construction of a valve timing adjusting device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a cam shaft that opens and closes intake and exhaust valves (not shown) of an internal combustion engine, and 2 denotes a timing pulley that is rotationally driven from a crank shaft (not shown) via a timing belt. Timing pulley 2
Is relatively rotatably fitted to the step portion 1a of the camshaft 1 by the portion of the bore 2a provided at the center, and is prevented from moving in the axial direction by the step portion 1a, the camshaft sleeve 3 and the bolt 4. There is. Camshaft sleeve 3
Is also fixed so as to rotate integrally with the cam shaft 1, using the pin 1b inserted into the shaft end through the hole.

The timing pulley 2 includes a camshaft 1
A cylindrical sleeve 5 is integrally formed on the coaxial line. An external tooth helical spline 3a is formed on the outer peripheral surface of the camshaft sleeve 3, and an inner tooth helical spline 3a is formed on the inner peripheral surface of the sleeve 5 of the pulley which faces the camshaft sleeve 3 with an annular gap therebetween. The spline 5a is formed. External tooth helical spline 3a
On the other hand, the internal tooth helical splines 5a have opposite twist angles, but in some cases, one of them may be a spline having axial straight teeth with a twist angle of 0 instead of the helical splines.

A substantially cylindrical control member 6 is provided in the annular gap between the camshaft sleeve 3 and the pulley sleeve 5.
Is inserted so as to be able to advance and retreat in the axial direction, the internal tooth helical spline 6a formed on the inner cylindrical surface of the control member 6 fits with the external tooth helical spline 3a of the camshaft sleeve 3, and The external tooth helical spline 6b formed on the outer cylindrical surface is the sleeve 5 of the pulley.
It is fitted with the internal tooth helical spline 5a.

As long as the axial position of the control member 6 does not change, the internal tooth helical spline 6a and the external tooth helical spline 6b have inner and outer camshaft sleeves 3 respectively.
Also, by fitting the helical splines 3a and 5a formed on the sleeve 5 of the pulley, the timing pulley 2 and the camshaft 1 are integrally rotated, and the rotation of the timing pulley 2 is transmitted to the camshaft 1. By sliding the control member 6 in the axial direction of the camshaft 1 during rotation, the engagement position between the external tooth helical spline 3a of the camshaft sleeve 3 and the internal tooth helical spline 5a of the pulley sleeve 5 is displaced. Connect the timing pulley 2 and the camshaft 1 to the helical splines 3a, 5
It can be relatively rotated in the opposite direction along the tooth trace of a. Therefore, by controlling the axial position of the control member 6, the rotational phase of the camshaft 1 with respect to the timing pulley 2, and thus the crankshaft of the internal combustion engine, can be adjusted steplessly during operation of the internal combustion engine.

In the illustrated embodiment, as a part of the phase control mechanism 7 for rotatably supporting and rotatably supporting the control member 6 in the axial direction of the camshaft 1, the camshaft 1 is extended in the housing 8. A ball screw mechanism including a shaft portion 9 fixed to the shaft portion and a nut portion 10 screwed to the shaft portion 9 and a ball bearing 11 in which an inner ring is press-fitted and supported at the tip of the nut portion 10 are used. In the shaft portion 9 and the nut portion 10, screw grooves provided on the outer circumference of the shaft portion 9 and the inner circumference of the nut portion 10 are screwed together through a large number of balls 10a rolling along them. A well-known ball circulation mechanism (not shown) that circulates the balls 10a when the nut portion 10 rotates with respect to the shaft portion 9 is provided. As a result, the ball screw mechanism has less friction than an ordinary screw, so that the nut portion 10 can be easily rotated with respect to the shaft portion 9 even with a small rotational force, and the nut portion 10 itself is a ball bearing. Control member 6 via 11
It is possible to smoothly move in the axial direction while supporting.

In order to completely fix the shaft portion 9 in the housing 8 in both the rotational direction and the axial direction, a flange 9a is provided at the left end of the shaft portion 9 in the illustrated embodiment.
Is formed, and a plurality of screws 9b passing through the holes of the housing 8 are screwed into the screw holes of the flange 9a of the shaft portion 9. The inner ring of the ball bearing 11 is held by means such as a circlip 11a so as not to come off from the right end step portion of the nut portion 10.
The outer ring 1 is also held by a means such as a circlip 11b so as not to come off from the stepped portion of the control member 6.

In order to transmit the rotation to the nut portion 10 of the ball screw mechanism which can move in the axial direction, the nut portion 1
One or more keyways 10b in the axial direction are formed on the outer cylindrical surface of 0, and the cylindrical rotor 12 is arranged so as to be loosely fitted to the outer cylindrical surface of the nut portion 10. Rotor 12
On the inner cylindrical surface of the, an axial projection 12a as a key is projected inward in the radial direction, and engages with the key groove 10b of the nut portion 10 irrespective of the axial movement. Rotation can be transmitted. Needless to say, the key connection having such a configuration is equivalent to a pin connection, a spline connection, or the like, and can be replaced by them.

The rotor 12 has a right end supported by a ball bearing 13 and a left end supported by a sliding bearing 8a formed in a part of the housing 8 so that the rotor 12 has a fixed shape. It is rotatably supported in a position but not axially moved. A worm wheel 14 is integrally attached to a part of the outer circumference of the rotor 12 by a method such as press fitting or wedge attachment. In addition, reference numeral 13 a in the drawing denotes a circlip for fixing the outer ring of the ball bearing 13 in the housing 8.

The housing 8 is attached to the cylinder head (or cylinder block) 15 of the internal combustion engine using the attaching stay 16, bolts 8b, 16a, etc., but in the first embodiment, the housing 8 is attached. An electric motor 17 is supported on the outside, and a worm 18 is formed at the tip of the rotary shaft of the electric motor 17 extending in the housing 8 and meshes with the worm wheel 14 described above. Since the electric motor 17 is rotationally controlled by a controller (not shown), the worm 18
Can be rotationally driven in the forward and reverse directions by an arbitrary rotation angle.

Next, the operation of the valve timing adjusting device as the first embodiment of the present invention shown in FIG. 1 will be described. When the operation of changing the valve timing during the engine operation is not performed, the timing pulley 2 is driven from the crankshaft via a timing belt (not shown), so that the control member 6 maintains its axial position while maintaining the ball position. Since it rotates together with the pulley sleeve 5 and the camshaft sleeve 3 on the bearing 11,
Since the timing pulley 2 and the cam shaft 1 rotate integrally, the control member 6 is merely a transmission member, and the valve timing is not changed by it.

When it is necessary to change the valve timing according to the operating conditions, a control device (not shown) sends a control signal to cause the electric motor 17 to move the worm 18 by the designated rotation angle in the forward or reverse direction. Drive in rotation. As a result, the worm wheel 14 is decelerated and rotates with the rotor 12, and the rotation is transmitted to the nut portion 10 via the engaging portion between the protrusion 12a on the inner surface of the rotor 12 and the key groove 10b. Since the shaft portion 9 of the ball screw mechanism is fixed in the housing 8 and the nut portion 10 is supported while being screwed onto the shaft portion 9 via the ball 10a, when the nut portion 10 rotates, the shaft portion 9 itself is rotated. It moves on the part 9 in the axial direction to the left or to the right, and only the axial movement component is the ball bearing 11.
Is transmitted to the control member 6 via. Therefore, even when the internal combustion engine is operating, the rotor 12 is driven by the electric motor 17.
If the control member 6 is rotated, the control member 6 can be moved in the left-right direction to an arbitrary position.
It depends on the rotation angle of the worm 18 by 7.

By adjusting and moving the control member 6 left and right, the external tooth helical of the camshaft sleeve 3 to which the internal tooth helical spline 6a and the external tooth helical spline 6b formed on the control member 6 are fitted. The engagement positions of the spline 3a and the pulley sleeve 5 with the internal tooth helical spline 5a move, and the twisting of the tooth trace causes relative rotation between the camshaft sleeve 3 and the pulley sleeve 5. As a result, the rotational phase of the timing pulley 2 and, by extension, the camshaft 1 with respect to the crankshaft changes, and the valve timing of an intake valve or an exhaust valve (not shown) that is driven to open and close by the camshaft 1 is changed.

In the valve timing adjusting apparatus of the first embodiment, as is clearly understood from FIG. 1, the nut portion 10 and the rotor 12 constituting the phase control mechanism 7, and further,
Worm wheel 14, worm 18, and electric motor 1
Since 7 etc. are arranged inside and outside at substantially the same position in the axial direction, even some of them are significantly shortened in the axial direction compared to the case where they are arranged in series in the axial direction. It This fixes the shaft portion 9 as well as the rotor 1
By connecting between 2 and the nut portion 10 by the protrusion 12a and the key groove 10b, not only the nut portion 10 can be rotated on the shaft portion 9 but also moved in the axial direction,
This is an effect obtained as a result of adopting a new configuration in which the nut portion 10 is provided with both a rotation transmission function and an axial sliding transmission function. In this way, the special configuration of the phase control mechanism 7 shortens the distance that the housing 8 projects from the cylinder head 15, thereby reducing the size of the entire valve timing adjusting device and narrowing the space such as the engine room of an automobile. It can be easily installed in various spaces.

A second embodiment of the invention is shown in FIG. The structure of the second embodiment is different from that of the first embodiment only in the drive portion of the phase control mechanism 7, and the protrusion 12a, the key groove 10b, and the key groove 10b after the rotor 12 in terms of the driving order. A series of configurations of the nut portion 10, the shaft portion 9, the ball bearing 11, the control member 6, etc. are the same as those in the first embodiment.

As a feature of the second embodiment, the rotor 12 has an enlarged diameter portion 12b integrally formed on the extension thereof, and the rotor 12 is arranged to rotate with the rotor 12 on the outer peripheral side of the enlarged diameter portion 12b. , Ring-shaped magnet (permanent magnet) 19
Is attached. A coil 20 surrounding the outer periphery of the ring-shaped magnet 19 with a slight gap is fixedly supported in the housing 8.
The ring-shaped magnet 19 and the coil 20 form a step motor 21. In the second embodiment, the step motor 21 is provided so as to be built in the housing 8. As a result, the worm wheel 14, the worm 18, the electric motor 17 and the like provided in the first embodiment are unnecessary. Further, since two ball bearings 13 can be arranged side by side in the axial direction, the sliding bearing portion 8a found in the first embodiment is eliminated.

In the second embodiment, the step motor 2 is used as an alternative to the electric motor 17 in the first embodiment.
Since 1 is incorporated in the housing 8, the step motor 21 is arranged so as to further surround the outside of the phase control mechanism 7 in which a large number of components are superposed at substantially the same position in the axial direction, as described above. And the first axial length is
Although the degree is similar to that of the embodiment, the protruding portion by the electric motor 17 is eliminated, and the entire valve timing adjusting device can be made more compact.

In the first and second embodiments illustrated and described,
All of them use a ball screw mechanism including a fixed shaft portion 9, a nut portion 10 that rotates and move in the axial direction, and a large number of balls 10a that engage them, but the shaft has a slightly increased frictional resistance. The same action and effect can be obtained by using an ordinary feed screw mechanism in which the nut portion and the nut portion are directly screwed together. In addition to the electric motor 17 and the step motor 21, various rotary drive devices can be used as substitutes for the drive portion of the phase control mechanism 7. Furthermore,
The engagement mechanism of the camshaft sleeve 3 and the pulley sleeve 5 with respect to the control member 6 is not limited to the one using the helical spline, but may be replaced by an equivalent mechanism using a slit, a cam or the like.

[0024]

In the valve timing adjusting device of the present invention, the rotation transmitting portion and the axial sliding transmitting portion of the phase control mechanism are both constituted by the nut member of the screw mechanism, and the shaft member is fixed in the housing. Of the constituent members of the phase control mechanism, it is possible to overlap the rotation transmitting portion and the axial movement transmitting portion at the same position in the axial direction, thereby increasing the axial length of the phase controlling mechanism. It can be significantly reduced. Also, the amount of overhang of the motor can be reduced. As a result, the overall length of the valve timing adjusting device in the axial direction is shortened, the physical size is reduced, and it is easy to mount it on a vehicle,
The motor support will also be stable.

As an additional effect, the varying thrust load acting on the control member and the nut member due to the rotational variation torque of the cam shaft during engine operation is directly fixed to the housing of the screw mechanism shaft. Since it is supported by the member, the rigidity of the supporting portion is increased as compared with the case where it is supported by the housing through ball bearings stacked in series as in the conventional case,
In the case of a ball screw, the durability is improved and troubles such as the generation of abnormal noise can be avoided. Furthermore, since the nut member and the rotor that rotationally drives it are coupled by means that transmits only rotation, the thrust load that fluctuates due to the rotational fluctuation torque of the camshaft is not directly transmitted to the worm gear mechanism, motor, etc. The durability is improved and the control position holding function is further improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the overall configuration of a valve timing adjusting device as a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the overall configuration of a valve timing adjusting device as a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Camshaft 2 ... Timing pulley 3 ... Camshaft sleeve 3a ... External tooth helical spline 5 ... Pulley sleeve 5a ... Internal tooth helical spline 6 ... Control member 6a ... Internal tooth helical spline 6b ... External tooth helical spline 7 ... Phase Control mechanism 8 ... Housing 9 ... Screw shaft portion 9a ... Flange 10 ... Screw nut portion 10a ... Ball 10b ... Key groove 11 ... Ball bearing 12 ... Rotor 12a ... Projection 12b ... Expanded portion 13 ... Ball bearing 14 ... Worm Wheel 15 ... Cylinder head of internal combustion engine 16 ... Mounting stay 17 ... Electric motor 18 ... Worm 19 ... Ring magnet 20 ... Coil 21 ... Step motor

Claims (1)

[Claims] 1. A rotary shaft which is formed between a crankshaft and a camshaft of an internal combustion engine and is coaxially supported between the rotary members, and which moves in the axial direction of the camshaft so as to rotate the two rotary members. Rotate the members relatively,
A valve timing adjusting device for an internal combustion engine, comprising: a control member that changes a rotational phase between a crankshaft and a camshaft; and a phase control mechanism that moves the control member in an axial direction. Includes a shaft member of a screw fixed in the housing, a nut member that is screwed onto the shaft member and can rotate, and a shaft member that can also move in the axial direction. And a rotor that does not move in the axial direction.