JPH04232312A - Variable valve timing device of engine - Google Patents

Abstract

PURPOSE:To constitute the variable valve timing device of an engine so as to be compact by making use of a planetary gear mechanism. CONSTITUTION:An engine output introducing part such as a pulley 13 and the like is arranged on the external periphery of the ring gear 8 of a planetary gear mechanism 6, and a planet gear 10 is supported by a planet carrier 11 fixed to a cam shaft 4, and also a bearing part 14 for supporting the cam shaft 4 is arranged on the engine body side end of the above-mentioned engine output introducing part. In addition, a sleeve 15 and the like, which is used for adjusting a phase angle between a crank shaft and the cam shaft 4, is arranged on a sun gear 9 so as to elongate a distance between the bearing part 14 and the cam shaft 4 toward the engine body side and to arrange a driving power introducing part on the tip of the sleeve 15.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides variable engine valve timing that controls the valve timing of intake and exhaust valves by adjusting the phase between the output shaft of the engine and a camshaft that is driven and connected to the output shaft. Regarding equipment.

0002

[Background Art] In a vehicle engine, for example, the stroke of a piston is controlled by hydraulic pressure, and the valve timing of intake and exhaust valves is adjusted by changing the phase of a crankshaft and a camshaft that are drivingly connected through a helical gear. Such a variable valve timing device has been used in the past. Further, as described in U.S. Pat. No. 4,747,375, for example, a planet gear is rotatably supported by a planet carrier integrally connected to a camshaft using a planetary gear mechanism, and the planetary gear mechanism The sun gear support shaft of the engine can be transmission connected to the engine output shaft, and the phase between the engine output shaft and the camshaft can be adjusted by controlling the rotation of the ring gear. In addition to rotatably supporting the ring gear, an output introduction part is provided on the outer periphery of the ring gear, and a servo mechanism is placed at the tip of the sun gear support shaft, so that the phase between the engine output shaft and the camshaft is adjusted by controlling the rotation of the sun gear. Variable valve timing devices are also known.

0003

[Problem to be Solved by the Invention] In the conventional variable valve timing device described above, which adjusts the phase between the crankshaft and the camshaft by controlling the stroke of the piston, the hydraulic piston is moved forward of the camshaft in the longitudinal direction of the engine. Because of this arrangement, the overall length of the engine inevitably becomes longer, making it difficult to mount the engine. Further, when controlling with hydraulic pressure in this manner, there is a problem that the viscosity of the oil changes depending on the oil temperature, and the responsiveness of the valve timing control changes depending on the environment.

[0004] Also, in the conventional valve timing device described above that uses a planetary gear mechanism, when adjusting the phase between the engine output shaft and the camshaft by controlling the rotation of the ring gear, a fairly large torque is required to drive the ring gear. Therefore, there is a problem that the servo mechanism etc. becomes large.Also, when adjusting the phase by controlling the rotation of the sun gear, connecting the servo mechanism to the tip side of the sun gear support shaft as described above does not allow the engine It is impossible to avoid increasing the total length.

The present invention has been made in view of the above-mentioned problems, and can be configured compactly by suppressing an increase in the longitudinal dimension of the engine and an increase in the size of the servo mechanism, and moreover, can be constructed in a compact manner without being influenced by the environment. It is an object of the present invention to provide a variable valve timing device for an engine that can obtain responsiveness of the engine.

[0006]

[Means for Solving the Problems] The present invention is an improved valve timing variable device for an engine that uses a planetary gear mechanism, in which an output introduction section that is transmission-connected to the output shaft of the engine by a belt or the like is connected to a planetary gear mechanism. The planet gear is installed on the outer periphery of the ring gear of the gear mechanism, and is rotatably supported by a planet carrier fixed to the valve drive camshaft.The sun gear receives the driving force for phase adjustment between the engine's output shaft and the camshaft. A two-shaft phase adjusting device for rotating the sun gear is provided, and a bearing portion for supporting the camshaft is provided at the engine body side end of the output introduction portion, and the two-shaft phase adjusting device is connected between the bearing portion and the cam. The driving force introduction part of the inter-shaft phase adjustment device is formed at the end of the engine main body side between the shaft and the engine body, and is configured to be drivingly connected to a servo mechanism such as a motor.

When the output introduction section is connected to the output shaft of the engine by a belt, in order to prevent the belt from deteriorating due to lubricating oil, a cover is attached to the end surface of the output introduction section on the side opposite to the engine body to cover the device. It is better to do this.

[0008]

[Operation] When the driving force is introduced from a servo mechanism such as a motor into the driving force introduction part and the two-axis phase adjustment device is driven, the sun gear connected to this two-axis phase adjustment device moves at an angle corresponding to the control amount. This changes the phase of the ring gear and planet carrier, which in turn changes the phase of the engine's output shaft and camshaft.

[0009] In such a device, the ring gear of the planetary gear mechanism is located on the inner periphery of the output introduction part that is transmission-coupled to the output shaft of the engine, and the two-shaft phase adjustment device provided on the sun gear is connected to the output shaft of the engine. Extending toward the engine body side between the bearing part and the camshaft provided on the engine body side of the section,
Since the driving force introduction part of the two-axis phase adjustment device is formed at the tip of the extended part, the width of the output introduction part that constitutes the pulley etc. is the size of the planetary gear mechanism and the two-axis phase adjustment device. The parts fit together, and the increase in overall engine length is suppressed. In addition, according to this device, the phase adjustment device between the two axes is driven by a servo mechanism such as a motor, and the sun gear is rotated to perform phase adjustment, so the control response is constant and is not affected by temperature changes. can be obtained, and the driving torque for phase adjustment can be small. Furthermore, since the bearing part supports the camshaft via the two-shaft phase adjustment device,
It is easy to increase the width and diameter to ensure rigidity against belt tension, etc., and therefore it is easy to position the planet gear and ring gear to expose their tooth surfaces.

Furthermore, when the output introduction section is connected to the output shaft of the engine by a belt, a cover is attached to the end surface of the output introduction section on the side opposite to the engine to cover the device, thereby preventing the belt from deteriorating due to lubricating oil. is prevented.

[0011]

[Embodiment] Hereinafter, an embodiment will be explained based on the drawings.

FIG. 1 is a partial sectional view of an engine according to an embodiment of the present invention, and FIG. 2 is a partial front view of the engine.

As shown in the figure, a camshaft 4 for driving an exhaust valve 3 is arranged in the upper part of the cylinder head 2 of the engine 1 in the direction of the cylinder row (left-right direction in FIG. 1). Although not shown in the figure, a camshaft for driving the intake valve is arranged in parallel with the camshaft 4 at the top of the cylinder head 2, and a camshaft for driving the intake valve is arranged at the bottom of the cylinder block 5 of the engine 1 in the direction of the cylinder row. The crankshaft is located on the The front end of the camshaft 4 for driving the exhaust valve 3 protrudes from the end face of the cylinder head 2 to the front side, and a valve consisting of a planetary gear mechanism 6 and a two-shaft phase adjustment device 7 is attached to the front end of the camshaft 4 for driving the exhaust valve 3. A variable timing device is installed.

The planetary gear mechanism 6 has a cylinder head 2.
A ring gear 8 is arranged concentrically at intervals around the end of the camshaft 4 that protrudes outward from the ring gear 8,
, a plurality of planet gears 10 arranged between the ring gear 8 and the sun gear 9, and a planet carrier 11 rotatably supporting the plurality of planet gears 10. It is configured.

A belt 12 is provided around the outer periphery of the ring gear 8.
A pulley 13 that is transmission-connected to the crankshaft is integrally formed, and a bearing portion 14 of the camshaft 4 extends from the engine body side (cylinder head 2 side) of the pulley 13. Further, a sleeve 15 is integrally provided on the engine body side of the sun gear 9 to rotate the sun gear 9 by receiving a driving force for phase adjustment between the crankshaft and the camshaft 4. The sleeve 15 extends toward the engine body between the bearing portion 14 and the camshaft 4, has a thrust surface for the camshaft 4 formed at its tip, and is driven in a manner that extends around the camshaft 4. A force introduction gear 16 is integrally formed, and the sleeve 15 and gear 16 constitute the two-axis phase adjusting device 7. Further, the planet carrier 11 is fixed to the end surface of the camshaft 4 by a bolt 17.

Further, a step motor 18 for controlling the phase adjustment device 7 between the two axes is disposed on the upper part of the head cover 19, and a gear of the phase adjustment device 7 between the two axes is connected to a shaft 20 of the step motor 18. A worm gear 21 that meshes with 16 is provided. This worm gear 21 is shown in FIG.
As shown in FIG. 2, it is located at the mating surface of the cylinder head 2 and head cover 19.

A cover 22 is attached to the end surface of the pulley 13 on the side opposite to the engine body to prevent oil leakage from the variable valve timing device.

In the case of the planetary gear mechanism 6, the output rotation is decelerated to about 2/3 of the input rotation. Therefore, the diameter of the pulley 13 on the outer periphery of the ring gear 8, which is the output introduction part of the planetary gear mechanism, can be made considerably smaller than the diameter of a normal camshaft pulley that reduces the speed by half in one stage relative to the crankshaft.

In the above embodiment, the variable valve timing device is provided in the exhaust valve drive mechanism of an engine, but the device of the present invention can also be applied to an intake valve drive mechanism.

[0020]

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to suppress an increase in the longitudinal dimension of the engine, and to suppress an increase in the size of the servo mechanism, thereby making it possible to form a variable valve timing device for the engine compactly. can. Furthermore, constant control that is not influenced by the environment can be performed using a motor or the like. Furthermore, by configuring a bearing portion with a large width and a large diameter across the two-axis phase adjustment device, it is possible to ensure the rigidity of the bearing portion against belt tension and the like and reduce mechanical resistance.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an engine according to an embodiment of the present invention.

[Figure 2] Partial front view of the engine

[Explanation of symbols]

1 Engine 2 Cylinder head 4 Camshaft 6 Planetary gear mechanism 7　Two-axis phase adjustment device 8 Ring gear 9 Sun gear 10 Planet gear 11 Planet carrier 13 Pulley 14 Bearing part 15 Sleeve 16 Gear (driving force introduction part) 22 Head cover

Claims (2)

[Claims] Claim 1: An output introduction part that is transmission-coupled to the output shaft of the engine is provided on the outer periphery of a ring gear of a planetary gear mechanism, and the planet gear of the planetary gear mechanism is rotatably mounted on a planet carrier fixed to a valve drive camshaft. support,
A variable valve timing device for an engine, wherein a sun gear of the planetary gear mechanism is provided with an inter-shaft phase adjustment device that rotates the sun gear by receiving a driving force for phase adjustment between the output shaft and the camshaft, A bearing part for supporting the camshaft is provided at the engine body side end of the output introduction part, and
A variable valve timing device for an engine, characterized in that the two-shaft phase adjusting device is disposed between the bearing portion and the camshaft, and a driving force introducing portion is formed at an end portion on the side of the engine body. 2. The variable valve timing for an engine according to claim 1, wherein the output introduction part is connected to the engine output shaft by a belt, and the device is covered by a cover attached to an end surface of the output introduction part on a side opposite to the engine body. Device.