JP2984799B2 - Variable engine valve timing mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing of an engine for controlling the valve timing of intake and exhaust valves by adjusting the phase of an output shaft of an engine and a camshaft operatively connected to the output shaft. Regarding the mechanism.

[0002]

2. Description of the Related Art In an engine for a vehicle or the like, the stroke of a piston is controlled by, for example, hydraulic pressure to change the phase of a crankshaft and a camshaft which are drivingly connected via a helical gear, thereby adjusting the valve timing of intake and exhaust valves. Such a variable valve timing device is conventionally used. Further, as described in, for example, U.S. Pat. No. 4,747,375, a planetary gear mechanism is used to rotatably support a planet gear on a planet carrier integrally connected to a cam shaft, and the planetary gear mechanism. The sun gear support shaft is operatively connected to the output shaft of the engine to adjust the phase between the output shaft of the engine and the cam shaft by controlling the rotation of the ring gear, or the planet gear is also connected to the planet carrier that is also integrally connected to the cam shaft. So that it can rotate freely, an output introduction section is provided on the outer periphery of the ring gear, and a servo mechanism is provided at the tip of the sun gear support shaft, so that the phase of the engine output shaft and cam shaft is adjusted by controlling the rotation of the sun gear. Such a variable valve timing device is also known.

[0003]

In the above conventional variable valve timing apparatus in which the phase of the crankshaft and the camshaft are adjusted by controlling the stroke of the piston, the hydraulic piston is moved forward of the camshaft in the engine longitudinal direction. Because of the arrangement, the overall length of the engine is inevitably increased and the mountability deteriorates. In addition, in the case of controlling with hydraulic pressure in this way, there is a problem that the response of the valve timing control changes depending on the environment due to a change in oil viscosity due to the oil temperature and the like.

Also, in the above-mentioned conventional valve timing device using a planetary gear mechanism, if the phase between the output shaft of the engine and the camshaft is adjusted by controlling the rotation of the ring gear, a considerably large torque is required to drive the ring gear. Therefore, there is a problem that the servo mechanism becomes large, and in the case of performing the phase adjustment by the rotation control of the sun gear, since the servo mechanism is connected to the tip side of the sun gear support shaft as described above, the engine The total length cannot be avoided. In order to control the rotation of the sun gear, instead of a mechanism in which a servo mechanism is connected to the tip side of the sun gear support shaft as in the above-described conventional device, a sleeve-shaped two shaft is connected from the end of the sun gear to the engine body side. It is conceivable to extend the inter-phase adjusting device to suppress the increase in the dimension in the engine cylinder row direction by using the leading end as a driving force introducing portion. When the two-shaft phase adjusting device is provided, the width of the variable valve timing mechanism itself in the camshaft direction increases accordingly. For example, a special case in which a bearing portion for camshaft bearing is overlapped on this sleeve-shaped portion. Aside from the case where the structure is adopted, the intended purpose of suppressing an increase in the dimension in the engine cylinder row direction is not sufficiently achieved.
Further, when the biaxial phase adjustment device extends in a sleeve shape as described above, there is also a problem that the mechanical resistance increases due to a large contact area with the camshaft.

The present invention has been made in view of the above problems, and has as its object to provide a compact valve timing variable mechanism of an engine using a planetary gear mechanism and having a small mechanical resistance.

[0006]

According to the present invention, there is provided a variable valve timing mechanism for an engine, wherein an output introducing portion which is operatively connected to an output shaft of the engine is provided on a ring gear of a planetary gear mechanism, and a planet gear is connected to a cam shaft for driving a valve. Valve timing of an engine provided rotatably supported by a planet carrier fixed to a sun gear, and provided with a sun gear receiving a driving force for adjusting the phase between the output shaft and the camshaft to rotate the sun gear. Variable mechanism, ring
Gear, sun gear, planet carrier and phase between two shafts
With adjustment device is supported on the cam shaft, it is extended from an end portion of the biaxial between phase adjusting device sun gear in a radial direction of the cam shaft
It is one in which the driving force introduction part of the two-axis between the phase adjustment device is <br/> formed at the tip of the biaxially between the position adjusting device is bent in the axial direction so as to cover the ring gear. In the case where the two-axis position adjusting device is configured to extend in the radial direction from the end of the sun gear and cover the ring gear at the tip, the output introducing portion is located at a lateral position on the cam shaft avoiding the outer periphery of the ring gear. It is good to arrange.

Further, by disposing the planetary gear mechanism above the head bolt for fixing the cylinder head, the dead space can be effectively utilized. In that case, in order to suppress the protrusion allowance of the crankshaft side transmission,
It is preferable to provide a bearing for camshaft support at the position of the end wall mating surface of the head cover, and to arrange an output introducing portion between the bearing and the planetary gear mechanism.

It is also possible that the bearing for camshaft support is located between the planetary gear mechanism and the output introduction part which rotates integrally with the ring gear of the planetary gear mechanism.

[0009] Further, when the driving device, which is drivingly connected to the driving force introducing portion of the biaxial phase adjusting device, is arranged on the mating surface of the head cover, the degree of freedom of layout is increased. In addition, since the planetary gear mechanism also serves as a speed reduction mechanism, the head cover line on the side to which the variable valve timing mechanism is applied can be kept low, so that the engine is compacted by tilting the engine in the left-right direction with respect to the cylinder row direction. Can be mounted.

[0010]

When the driving force is introduced from a servo mechanism such as a motor into the driving force introducing section and the two-axis phase adjustment device is driven, the sun gear connected to the two-axis phase adjustment device changes the angle corresponding to the control amount. , The phase of the ring gear and the planet carrier changes, and the phase of the output shaft of the engine and the cam shaft change.

In such a device, a biaxial phase adjusting device extends from the end of the sun gear in the radial direction of the camshaft,
Since the distal end is bent in the axial direction so as to cover the ring gear, and the driving force introducing portion is formed therein, the width of the variable valve timing mechanism in the cam shaft direction can be suppressed as small as possible. In addition, since the length from the center of the camshaft to the driving force introduction portion is long, the driving torque can be further reduced.

A planetary gear mechanism is disposed above the head bolt, and a bearing for camshaft support is provided at the position of the end wall mating surface of the head cover, and an output is introduced between the bearing and the planetary gear. By arranging the parts, the dead space on the Hebbolt is effectively used, and the projection allowance of the crankshaft-side sprocket and the like that is operatively connected to the output introduction part is suppressed to be small.

When a bearing portion is formed between the planetary gear mechanism and the output introduction portion, specifically, a structure in which a connecting portion between the ring gear and the output introduction portion is disposed between the bearing portion and the camshaft. Therefore, it is easy to secure rigidity against bending and reduce mechanical resistance. Also in this case, the dead space can be effectively utilized by disposing the planetary gear mechanism above the head bolt.

[0014] Further, since the driving device that is drivingly connected to the driving force introducing portion of the biaxial phase adjustment device is disposed on the mating surface of the head cover, the degree of freedom in the layout of the driving device is increased.

Further, since the planetary gear mechanism also serves as a speed reduction mechanism, the height of the entire apparatus including the output introducing section can be suppressed low. In this case, a compact mounting can be realized by using a slant structure for the engine. .

[0016]

Embodiments will be described below with reference to the drawings.

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

In this embodiment, camshafts 3 and 4 for driving an intake valve and for driving an exhaust valve are arranged above a cylinder head 2 of the engine 1 in parallel to the cylinder row direction (left-right direction in FIG. 1). I have. In addition, a crankshaft (not shown) is arranged in the cylinder row direction below the cylinder block (not shown) of the engine 1.

The cam shaft 4 for driving the exhaust valve is provided on the end wall of the cylinder head 2 at a position where the front end of the cam shaft 4 is aligned with the end wall of the head cover 5 mounted on the cylinder head 2. It is supported by the bearing 6. Also, the front end of the camshaft 3 for driving the intake valve is also
Similarly, it is supported by a bearing (not shown) formed on the end wall of the cylinder head 2.

The cam shaft 4 for driving the exhaust valve includes a planetary gear mechanism 10 located in a space above the front head bolt 7 adjacent to the inside of the bearing 6 and a phase adjusting device 20 between the two shafts. A variable valve timing device is installed.

The planetary gear mechanism 10 includes a ring gear 11 disposed concentrically around the end of the camshaft 4 at intervals.
And a sun gear 12 rotatably mounted on the camshaft 4 inside thereof, a plurality of planet gears 13 disposed between the ring gear 11 and the sun gear 12, and rotatably supporting the plurality of planet gears 13. And a planet carrier 14.

A sprocket 32 rotatably supported on the camshaft 4 is rotatably connected to an end of the ring gear 11 on the side facing the bearing 6 via a radial connecting member 31. I have. At the end of the sun gear 12 remote from the sprocket 32, an arm member 21 for rotating the sun gear 9 by receiving a driving force for phase adjustment between the crankshaft and the camshaft 4 is fixed. The arm member 21 extends in the radial direction on the back side of the planet gear 13, and its tip is bent in the axial direction so as to cover the outer periphery of the ring gear 11, and the outer periphery of the tip receives a driving force for phase adjustment. The introduction gear 22 is formed, and the arm member 21 and the gear 22 constitute the biaxial phase adjustment device 20. Also,
The portion of the planet carrier 14 extending between the sun gear 12 and the camshaft 4 is fixedly mounted on the camshaft 4, and the end surface thereof is a thrust surface for the camshaft 4.

The inter-axis phase adjusting device 20 includes the gear 22
Step motor 41 via worm gear 40 meshing with
Is driven and controlled.

The camshaft 3 for driving the intake valve is provided with a sprocket 33 at a position aligned with the sprocket 32 on the camshaft 4 for driving the exhaust valve, and these two sprockets 32 and 33 and the crankshaft side are shown. And a sprocket that is not connected by a single timing chain 34. Here, since the planetary gear mechanism 10 also serves as a speed reduction mechanism, the output rotation is reduced to about に 対 し of the input rotation, so that the rotation is reduced to に 対 し in one step with respect to the crankshaft. The diameter of the pulley 31 on the exhaust side is smaller than that of the pulley 33 on the intake side. The variable valve timing device can be provided on the intake side.

According to the above embodiment, the space above the head bolt 7 is effectively used for the variable valve timing mechanism, the amount of projection of the camshaft 4 to the front side is reduced, and the camshaft is supported. By arranging the sprocket 32 inside the front-side bearing portion 6, the protrusion on the front side of the crankshaft that is operatively connected by the sprocket 32 via the timing chain 34 can be reduced.

FIG. 3 is a partial side sectional view of an engine according to a second embodiment of the present invention, and FIG. 4 is a partial front sectional view of the same. As is apparent from the drawing, also in this embodiment, the camshafts 3 and 4 for driving the intake valve and driving the exhaust valve are arranged in the upper part of the engine 1 in parallel with the cylinder row direction. Has a crankshaft (not shown) also arranged in the cylinder row direction. In this embodiment, the front bearing 6 (not shown) of the intake valve driving camshaft 3 and the front bearing (not shown) of the exhaust valve driving camshaft 4 are located above the cylinder head 2 in the head cover 5. It is provided in. The camshaft 3 for driving the intake valve is provided with the planetary gear mechanism 10 and the two-axis phase adjusting device 20 at a position inside the bearing 6 and above the head bolt 7 on the front side.
A variable valve timing device consisting of
A sprocket 35 for introducing power is arranged at a shaft end position sandwiching the bearing 6.

The sprocket 35 is used for the planetary gear mechanism 1
0 is fitted to the axially extending portion 36 of the connecting member 31 connected to the ring gear 11, and the extending portion 36 of the connecting member 31 is disposed between the bearing 6 and the camshaft 4. It has a structure. Ring gear 11, sun gear 1
2, planet gear 13 and planet carrier 14
The structure of the planetary gear mechanism composed of, and the structure of the biaxial phase adjusting device 20 composed of the arm member 21 and the gear 22 are the same as those of the first embodiment. In addition, in order to drive and control the two-axis phase adjusting device 20, the step motor 4 is also used.
1 is provided, and its driving force is transmitted via a worm gear 40 and a driving force introducing gear 40 to the two-axis phase adjusting device 20.
Will be introduced.

As shown in FIG. 4, the worm gear 40 is provided at the position of the mating surface of the head cover 5, and a step motor 41 is disposed above the worm gear 40. Further, a sprocket 37 is provided on the exhaust valve driving camshaft 4 at a position aligned with the sprocket 35 on the intake valve driving camshaft 3.
These two sprockets 35 and 37 and a sprocket (not shown) on the crankshaft side are operatively connected by a single timing chain 34.

In the case of this embodiment, the planetary gear mechanism 10
Is provided on the intake side, so that the diameter of the pulley 35 on the intake side is small. This variable valve timing device may be provided on the exhaust side.

According to the second embodiment, the space above the head bolt 7 can also be effectively utilized, and the arrangement of the worm gear 40 and the step motor 41 as driving devices is easy.

FIG. 5 is a partial side sectional view of an engine according to a third embodiment of the present invention, and FIG. 6 is a partial front sectional view of the engine. In this embodiment, camshafts 3 and 4 for driving an intake valve and for driving an exhaust valve are also arranged in the upper part of the engine 1 in parallel to the cylinder row direction, and a crankshaft (not shown) is arranged in the lower part of the engine 1. Are arranged in the cylinder row direction. In this embodiment, the front bearing 6 (not shown) of the intake valve driving camshaft 3 and the front bearing (not shown) of the exhaust valve driving camshaft 4 are located above the cylinder head 2 in the head cover 5. In the camshaft 3 for driving the intake valve, a variable valve timing device including a planetary gear mechanism 10 and a biaxial phase adjusting device 20 is disposed outside the bearing 6. A sprocket 32 for introducing power is arranged between the bearing 10 and the bearing 6.

The planetary gear mechanism 10, the biaxial phase adjusting device 20 and the sprocket 32 of this embodiment have the same structures as those of the first embodiment shown in FIGS. 1 and 2, respectively. These are mounted as a unit from the end of the camshaft 3 in a direction opposite to that of the first embodiment. The sprocket 32 on the intake valve driving camshaft 3 and the sprocket (not shown) on the crankshaft side are operatively connected by a single timing chain 34. Further, a step motor 41 is also provided to drive and control the inter-axis phase adjusting device 20, and the driving force is introduced into the inter-axis phase adjusting device 20 via the worm gear 40 and the driving force introducing gear 40. It is configured to:

The intake valve driving camshaft 3 and the exhaust valve driving camshaft 4 are provided with sprockets 37 at positions above the front head bolt 7 inside the front bearing 6.
38 are provided respectively, and these sprockets 37, 3
8 are drivingly connected by a timing chain 39.

In the case of this embodiment, the planetary gear mechanism 10
Is provided on the intake side, the diameter of the pulley 35 on the intake side is reduced, and the camshaft 3 for driving the intake valve, which is decelerated by the planetary gear mechanism, is connected to the camshaft for driving the exhaust valve. Since the drive shaft 4 is driven and connected via the timing chain 39, the diameter of the sprocket 38 of the cam shaft 4 for driving the exhaust valve is also reduced. Therefore, the height of the head cover 5 is reduced as a whole. The variable valve timing device may be provided on the exhaust side.

In the case of the third embodiment, the space above the head bolt 7 is also effectively utilized.

According to each of the above embodiments, the head cover line can be lowered on at least one side, so that the engine can be mounted compactly by tilting the engine in the left-right direction with respect to the cylinder row direction.

[0037]

Since the present invention is constructed as described above, the variable valve timing mechanism for adjusting the phase between two shafts by driving the sun gear of the planetary gear mechanism has a reduced width in the camshaft direction. It can be kept small and compact and have low mechanical resistance.

Further, by disposing a planetary gear mechanism above the head bolts, providing a bearing at the mating surface position of the head cover end wall, and disposing an output introducing portion between the bearing and the planetary gear, The dead space of the bolt can be effectively used, and the protrusion allowance of the crankshaft-side sprocket and the like can be reduced.

Further, by forming a bearing portion between the planetary gear mechanism and the output introducing portion, a connecting portion between the ring gear and the output introducing portion is disposed between the bearing portion and the camshaft to increase rigidity. Mechanical resistance can be reduced.

Further, by arranging the driving device for the phase adjustment at the position of the mating surface of the head cover, the layout of the driving device becomes easy.

Further, the engine having the variable valve timing mechanism of the present invention can keep the overall height of the engine low by adopting the slant structure.

[Brief description of the drawings]

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

FIG. 2 is a partial front view of the engine.

FIG. 3 is a partial side sectional view of an engine according to a second embodiment of the present invention.

FIG. 4 is a front partial front view of the engine.

FIG. 5 is a partial side sectional view of an engine according to a third embodiment of the present invention.

FIG. 6 is a front partial front view of the engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder head 3 Cam shaft (for driving an intake valve) 4 Cam shaft (for driving an exhaust valve) 6 Bearing part 7 Head bolt 10 Planetary gear mechanism 11 Ring gear 12 Sun gear 13 Planet gear 14 Planet carrier 20 Phase adjusting device between two shafts Reference Signs List 21 arm member 22 gear (driving force introduction part) 31 connecting member 32 sprocket (output introduction part) 35 sprocket (output introduction part) 36 extended part

Continuation of the front page (56) References JP-A-3-88907 (JP, A) JP-A-59-9904 (JP, U) JP-A-61-226056 (JP, U) JP-A-1-142501 (JP) , U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F01L 1/34

Claims (5)

(57) [Claims] An output introduction portion, which is operatively connected to an output shaft of an engine, is provided on a ring gear of a planetary gear mechanism, and a planet gear of the planetary gear mechanism is rotatably supported on a planet carrier fixed to a valve driving cam shaft. An engine valve timing variable mechanism provided with a biaxial phase adjustment device that rotates a sun gear of a sun gear of the planetary gear mechanism by receiving a driving force for adjusting a phase between the output shaft and the camshaft, The ring gear, the sun gear, and the planet carrier;
Gear and the phase adjusting device between the two shafts are supported on the cam shaft.
Together with the said biaxial between the phase adjustment device is extended in the radial direction of the cam shaft from an end portion of said sun gear, said double the tip of the biaxially between the position adjusting device is bent in the axial direction so as to cover the ring gear engine variable valve timing mechanism, wherein the driving force introduction part of the shaft between the phase adjustment device is formed. 2. A planetary gear mechanism is arranged above a head bolt for fixing a cylinder head, and a bearing for camshaft support is provided at a position of an end wall side mating surface of a head cover. 2. The valve timing mechanism for an engine according to claim 1, wherein the output introduction portion is disposed between the engine and the gear mechanism. 3. The variable valve timing mechanism of an engine according to claim 1, wherein a bearing portion for supporting a camshaft is formed between the planetary gear mechanism and an output introduction part which rotates integrally with the ring gear of the planetary gear mechanism. 4. The variable valve timing mechanism of an engine according to claim 1, wherein a driving device which is drivingly connected to the driving force introducing portion of the biaxial phase adjustment device is arranged on a mating surface of the head cover. 5. The variable valve timing mechanism for an engine according to claim 1, wherein the engine is arranged to be inclined in the left-right direction with respect to the cylinder row direction.