JPH04232313A - Variable valve timing device of engine - Google Patents

Abstract

PURPOSE:To get the variable valve timing device of an engine, which has a compact size and a low mechanical resistance, by making use of a planetary gear mechanism. CONSTITUTION:An engine output introducing part such as a sprocket wheel 32 and the like is provided so as to rotate integrally with the ring gear 11 of a planetary gear mechanism 10, and an arm member 21 which is fixed to a cam shaft 4 supports a planet gear 13 by a planet carrier 14 and constitutes a device 20 for adjusting a phase between two axes is fixed to the end part of a sun gear 12. The above-mentioned arm member 21 is elongated in the radial direction of the cam shaft 4 from the end part of the sun gear 12 so that its end is bent in the axial direction so as to cover the ring gear 11. On the outer circumference of the tip of the arm member 21, a gear 22 is arranged in order to receive driving power from a stepping motor 41 and the like for adjusting phase. In addition, a dead space is effectively utilized, for example, by arranging the portion of a planetary gear mechanism 10 in a space above cylinder-head bolts 7.

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 the mechanism.

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 engine, an output introduction part 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 between the engine output shaft and the cam shaft 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 oil pressure in this way, 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, adjusting the phase between the engine output shaft and the camshaft by controlling the rotation of the ring gear requires a fairly large torque to drive the ring gear. Therefore, there is a problem that the servo mechanism etc. becomes large.In addition, in the case where phase adjustment is performed by controlling the rotation of the sun gear, the servo mechanism is connected to the tip side of the sun gear support shaft as described above, so the engine It is impossible to avoid increasing the total length. In addition, in order to control the rotation of the sun gear, instead of using a mechanism in which a servo mechanism is connected to the tip side of the sun gear support shaft as in the conventional device described above, a sleeve-shaped biaxial shaft is connected from the end of the sun gear to the engine body side. It may be possible to suppress the increase in dimension in the direction of the engine cylinder row by extending the phase adjustment device and using its tip as the driving force introduction part, but it is possible to suppress the size increase in the engine cylinder row direction. When a two-shaft phase adjustment device is installed, the width of the variable valve timing mechanism itself in the camshaft direction becomes correspondingly larger, so it is necessary to use a special method such as overlapping a bearing part for supporting the camshaft on this sleeve-shaped part. Apart from the case where this structure is adopted, the intended purpose of suppressing the increase in dimensions in the direction of the engine cylinder row cannot be sufficiently achieved. Further, if the two-axis phase adjustment device extends in the shape of a sleeve as described above, there is a problem that mechanical resistance increases because the contact area with the camshaft is large.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a variable valve timing mechanism for an engine that is compact and has low mechanical resistance using a planetary gear mechanism.

[0006]

[Means for Solving the Problems] A variable valve timing mechanism for an engine according to the present invention includes a ring gear of a planetary gear mechanism that includes an output introduction portion that is transmission-coupled to the output shaft of the engine, and a planet gear connected to a camshaft for driving a valve. Valve timing of an engine is provided with a two-shaft phase adjusting device which is rotatably supported by a planet carrier fixed to and rotates the sun gear by receiving a driving force from the sun gear for adjusting the phase between the output shaft and the camshaft. A variable mechanism, in particular,
A two-axis phase adjustment device is installed extending from the end of the sun gear in the radial direction of the camshaft, and the driving force of the two-axis phase adjustment device is attached to the tip of the two-axis position adjustment device that is bent in the axial direction so as to cover the ring gear. It forms an introduction part. When the two-shaft position adjustment device is configured to extend radially from the end of the sun gear so that the tip covers the ring gear, the output introduction section is placed at a side position on the camshaft avoiding the outer periphery of the ring gear. It is good to place it.

Furthermore, dead space can be effectively utilized by arranging the planetary gear mechanism above the head bolts that fix the cylinder head. In that case, in order to suppress the protrusion of the crankshaft side transmission device, a bearing for supporting the camshaft is provided at the position of the mating surface of the end wall of the head cover, and an output is placed between this bearing and the planetary gear mechanism. It is best to place an introduction section.

[0008] Furthermore, it is also possible to configure the camshaft supporting bearing portion to be located between the planetary gear mechanism and the output introduction portion that rotates integrally with the ring gear of the planetary gear mechanism.

[0009] Further, the degree of freedom in layout is increased by arranging the driving device drivingly connected to the driving force introducing portion of the two-axis phase adjustment device on the mating surface of the head cover. In addition, since the planetary gear mechanism doubles as a reduction mechanism, the head cover line on the side to which the variable valve timing mechanism is applied can be kept low, making it possible to make the engine more compact by tilting it left and right with respect to the direction of the cylinder row. It is possible to install it.

0010

[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.

In such a device, a two-shaft phase adjustment device extends from the end of the sun gear in the radial direction of the camshaft,
By bending the tip end in the axial direction to cover the ring gear and forming the driving force introduction part there, the width of the variable valve timing mechanism in the camshaft direction can be kept as small as possible. Moreover, since the length from the center of the camshaft to the driving force introduction part is long, the driving torque can be further reduced.

Further, a planetary gear mechanism is arranged above the head bolt, and a bearing part for supporting the camshaft is provided at the position of the mating surface of the end wall part of the head cover, and an output is introduced between the bearing part and the planetary gear. By arranging the section, the dead space on the head bolt can be effectively utilized, and the protrusion of the crankshaft side sprocket, etc. that is transmission-coupled to the output introduction section can be kept small.

[0013] Furthermore, in the case where a bearing part is formed between the planetary gear mechanism and the output introduction part, specifically, a structure in which the connecting part between the ring gear and the output introduction part is arranged between the bearing part and the camshaft is used. Therefore, it becomes easy to ensure rigidity against bending and reduce mechanical resistance. Furthermore, in this case as well, dead space can be effectively utilized by arranging the planetary gear mechanism above the head bolt.

[0014] Furthermore, by disposing the driving device drivingly connected to the driving force introducing portion of the two-axis phase adjustment device on the mating surface of the head cover, the degree of freedom in layout of the driving device is increased.

[0015] Furthermore, since the planetary gear mechanism also serves as a reduction mechanism, the height of the entire device including the output introduction section can be kept low, and in this case, the engine can be installed in a compact manner by having a slant structure. .

[0016]

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

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

In this embodiment, camshafts 3 and 4 for driving intake valves and exhaust valves are arranged in the upper part of the cylinder head 2 of the engine 1 in parallel to the direction of the cylinder row (the left-right direction in FIG. 1). There is. Further, a crankshaft (not shown) is also arranged below the cylinder block (not shown) of the engine 1 in the direction of the cylinder row.

The camshaft 4 for driving the exhaust valve is provided with its front end on the end wall of the cylinder head 2 at a position where the end wall mating surface of the head cover 5 is attached to the cylinder head 2. It is supported by a bearing part 6. In addition, the front end of the camshaft 3 for driving the intake valve is also
Similarly, it is supported by a bearing portion (not shown) formed on the end wall of the cylinder head 2.

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

The planetary gear mechanism 10 includes a ring gear 11 arranged concentrically at intervals around the end of the camshaft 4.
, a sun gear 12 rotatably attached to the camshaft 4 inside thereof, a plurality of planet gears 13 disposed between the ring gear 11 and the sun gear 12, and a rotatable support for the plurality of planet gears 13. It is composed of a planet carrier 14.

A sprocket 32 rotatably supported on the camshaft 4 is connected to the end of the ring gear 11 facing the bearing 6 via a radial connecting member 31 so as to be rotatable therewith. There is. Furthermore, an arm member 21 is fixed to the end of the sun gear 12 that is far from the sprocket 32 and receives a driving force to rotate the sun gear 9 in order to adjust the phase between the crankshaft and the camshaft 4. The arm member 21 extends radially on the back side of the planet gear 13, has a tip bent in the axial direction so as to cover the outer periphery of the ring gear 11, and receives a driving force for phase adjustment on the outer periphery of the tip. An introduction gear 22 is formed, and the arm member 21 and gear 22 constitute the two-axis phase adjustment device 20. Also,
A portion of the planet carrier 14 extending between the sun gear 12 and the camshaft 4 is attached and fixed to the camshaft 4, and its end surface is a thrust surface for the camshaft 4.

The two-axis phase adjusting device 20 has the above-mentioned gear 22.
Step motor 41 via worm gear 40 that meshes with
Drive controlled by.

Further, the intake valve driving camshaft 3 is provided with a sprocket 33 on the exhaust valve driving camshaft 4 at a position parallel to the sprocket 32, and these two sprockets 32, 33 and the crankshaft side shown in the figure are provided with a sprocket 33. A single timing chain 34 is used to transmit and connect the sprocket and the other sprockets. Here, the planetary gear mechanism 10 also serves as a speed reduction mechanism, and the output rotation is reduced to about 2/3 of the input rotation, so it is configured to reduce the rotation to 1/2 in one stage relative 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. Note that this variable valve timing device can also be provided on the intake side.

According to the above embodiment, the space above the head bolt 7 is effectively utilized for the variable valve timing mechanism, the amount of protrusion of the camshaft 4 toward the front side is kept small, and the camshaft is supported. By arranging the sprocket 32 inside the front side bearing portion 6, the front side protrusion of the crankshaft to which the sprocket 32 is transmission-connected via the timing chain 34 can be kept small.

FIG. 3 is a side partial sectional view of an engine according to a second embodiment of the present invention, and FIG. 4 is a front partial sectional view thereof. As is clear from the figure, in this embodiment as well, the camshafts 3 and 4 for driving intake valves and exhaust valves are arranged parallel to the cylinder row direction in the upper part of the engine 1, and The crankshaft (not shown) is also arranged in the cylinder row direction. In the case of this embodiment, the front side bearing part 6 of the intake valve driving camshaft 3 and the front side bearing part (not shown) of the exhaust valve driving camshaft 4 are located in the upper part of the cylinder head 2 within the head cover 5. It is set in. On the camshaft 3 for driving the intake valve, a variable valve timing device consisting of a planetary gear mechanism 10 and a phase adjustment device 20 between two shafts is installed at a position above the head bolt 7 on the front side inside the bearing portion 6. Further, a sprocket 35 for introducing output is arranged at the shaft end position sandwiching the bearing part 6.

The sprocket 35 is connected to the planetary gear mechanism 1.
The connecting member 31 is fitted into an axially extending portion 36 of a connecting member 31 connected to the ring gear 11 of No. It has a built-in structure. Ring gear 11, sun gear 1
2. Planet gear 13 and planet carrier 14
The structure of the planetary gear mechanism consisting of the two shafts and the structure of the inter-axis phase adjusting device 20 consisting 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 inter-axis phase adjustment device 20, the step motor 4 is also used.
1 is provided, and its driving force is transmitted through a worm gear 40 and a driving force introducing gear 40 to a two-axis phase adjustment device 20.
will be introduced in

As shown in FIG. 4, the worm gear 40 is provided at a mating surface position of the head cover 5, and a step motor 41 is provided above it. 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 transmission-connected by one timing chain 34.

In this embodiment, the planetary gear mechanism 10
Since the variable valve timing mechanism using the valve timing mechanism is provided on the intake side, the diameter of the pulley 35 on the intake side is small. Note that 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 be effectively utilized, and the worm gear 40 and step motor 41, which are driving devices, can be easily arranged.

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

The planetary gear mechanism 10, inter-axis phase adjustment device 20, and sprocket 32 of this embodiment have the same structure as that of the first embodiment shown in FIGS. 1 and 2, respectively. These components are installed as a unit from the end of the camshaft 3 in the opposite direction to that of the first embodiment. The sprocket 32 on the intake valve driving camshaft 3 and a sprocket (not shown) on the crankshaft side are transmission connected by one timing chain 34. Further, in order to drive and control the phase adjustment device 20 between two axes, a step motor 41 is also provided, and its driving force is introduced into the phase adjustment device 20 between two axes via a worm gear 40 and a gear 40 for introducing driving force. It is configured so that

The intake valve driving camshaft 3 and the exhaust valve driving camshaft 4 have a sprocket 37 located inside the front bearing 6 and above the front head bolt 7.
38 are provided respectively, and these sprockets 37, 3
8 are transmission-connected by a timing chain 39.

In this embodiment, the planetary gear mechanism 10
By providing a variable valve timing device on the intake side, the diameter of the pulley 35 on the intake side becomes smaller, and the camshaft 3 for driving the exhaust valve is connected to the camshaft 3 for driving the intake valve, which is decelerated by the planetary gear mechanism. 4 are transmission-connected via the timing chain 39, the diameter of the sprocket 38 of the exhaust valve driving camshaft 4 is also reduced. Therefore, the overall height of the head cover 5 can be suppressed. Note that 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 embodiments described above, the head cover line can be lowered on at least one side, and therefore, compact mounting is possible by tilting the engine in the left-right direction with respect to the direction of the cylinder row.

[0037]

Effects of the Invention Since the present invention is constructed as described above, the variable valve timing mechanism, which adjusts the phase between two shafts by driving the sun gear of a planetary gear mechanism, can be used to adjust the width in the camshaft direction. It can be kept small and compact and have low mechanical resistance.

Furthermore, by arranging the planetary gear mechanism above the head bolt, providing a bearing part at the mating surface position of the end wall of the head cover, and arranging the output introduction part between the bearing part and the planetary gear, the head The dead space of the bolt can be effectively utilized, and the protrusion of the crankshaft sprocket, etc. can be kept small.

Furthermore, by forming a bearing section between the planetary gear mechanism and the output introduction section, the connecting section between the ring gear and the output introduction section is arranged between the bearing section and the camshaft, increasing the rigidity. Mechanical resistance can be reduced.

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

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

[Brief explanation of the drawing]

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

[Figure 2] Front partial front view of the same engine

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

[Figure 4] Front partial front view of the same engine

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

[Figure 6] Front partial front view of the same engine

[Explanation of symbols]

1 Engine 2 Cylinder head 3 Camshaft (for intake valve drive) 4 Camshaft (for exhaust valve drive) 6 Bearing part 7 Head bolt 10 Planetary gear mechanism 11 Ring gear 12 Sun gear 13 Planet gear 14 Planet carrier 20　Two-axis phase adjustment device 21 Arm member 22 Gear (driving force introduction part) 31 Connecting member 32 Sprocket (output introduction part) 35 Sprocket (output introduction part) 36 Extension part

Claims (5)

[Claims] Claim 1: An output introduction part that is transmission-coupled to the output shaft of the engine is provided on a ring gear of a planetary gear mechanism, and the planet gear of the planetary gear mechanism is rotatably supported by a planet carrier fixed to a valve drive camshaft. , a variable valve timing mechanism for an engine in which 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, The two-shaft phase adjusting device is installed to extend in the radial direction of the camshaft from the end of the sun gear, and the two-shaft phase adjusting device is installed at the tip of the two-shaft position adjusting device that is bent in the axial direction so as to cover the ring gear. A variable valve timing mechanism for an engine, characterized in that a driving force introduction part of an adjustment device is formed. 2. A planetary gear mechanism is disposed above the head bolt that fixes the cylinder head, and a bearing part for supporting the camshaft is provided at the position of the mating surface on the end wall side of the head cover, and the planetary gear mechanism is connected to the bearing part and the planetary gear mechanism. 2. The valve timing mechanism for an engine according to claim 1, wherein the output introduction part is disposed between the gear mechanism and the gear mechanism. 3. The variable valve timing mechanism for an engine according to claim 1, wherein a bearing for supporting a camshaft is formed between a planetary gear mechanism and an output introduction section that rotates integrally with a ring gear of the planetary gear mechanism. 4. The variable valve timing mechanism for an engine according to claim 1, wherein a driving device drivingly connected to the driving force introducing portion of the inter-axle phase adjustment device is disposed 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 laterally with respect to the direction of the cylinder row.