JP3272245B2 - Chain cover structure of 4-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a chain cover for covering an outer surface of an engine body, and more particularly to a chain cover structure of a four-cycle engine provided with a variable valve timing device (VVT).

[0002]

2. Description of the Related Art In order to change the opening / closing timing of an intake / exhaust valve in accordance with the operation state of an engine, a change in hydraulic pressure applied to a cam shaft for valve drive via a solenoid valve for hydraulic control is used. In a four-stroke engine equipped with a variable valve timing device (VVT) for changing the phase angle between a cam sprocket and a camshaft, the variable valve timing device is usually covered with a chain cover on the outside and covered with a cylinder head cover on the top. It is installed on the outer side of the upper part of the broken cylinder head and on the outer end portion of the valve driving cam shaft protruding outward from the cylinder head.

In a four-stroke engine equipped with such a variable valve timing device, the supply of working oil from the oil supply unit of the variable valve timing device to the variable operation unit is performed not by the journal bearing side of the cylinder head but by the chain cover. Conventionally, in order to form the oil passage from the cylinder head to the solenoid valve of the oil supply unit in the engine body, the upper portion of the cylinder head and the chain cover (the outer surface of the cylinder head) And the oil supply portion of the variable valve timing device is formed as an upper semicircular arch-shaped member formed separately from the chain cover, and the upper end of the chain cover itself. To the mounting part consisting of the lower semicircular concave part There.

[0004]

By the way, in the conventional four-stroke engine in which the upper parts of the cylinder head and the chain cover are formed as one member as described above, the upper part of the chain cover that covers the outside of the timing chain is formed. Since it cannot be removed from the cylinder head, the assembling workability when assembling a chain guide, a tensioner, or the like to the engine body is poor.

Further, since the mounting portion for mounting the oil supply portion of the variable valve timing device is formed of two members, the number of parts is increased, and the mounting portion on the mounting portion side with respect to the mating surface on the oil supply portion side is increased. Since the surfaces are the two surfaces of the front surface of the arch-shaped member and the front surface of the concave portion of the chain cover, the mating surface between the oil supply unit and the mounting part is three-sided, and the sealing performance of the part is not good. Has become.

Further, the cylinder heads of the V-type engine for each of the V-shaped cylinder rows are manufactured to have the same structure so that they can be shared with each other, and are used after being arranged in the opposite directions in the cam shaft direction. In such a case, the chain cover portions must be formed integrally with both ends of the cylinder head in the cam shaft direction,
For this reason, an extra chain cover portion exists on one end side in the cam axis direction of each cylinder head, and the length of the cylinder head in the cam axis direction becomes unnecessarily long.

[0007]

According to the present invention, in order to solve the above-mentioned problems, as described in the first aspect, the outside is covered with a chain cover and the upper part is covered with a cylinder head cover. In the upper outside of the cylinder head, the cam sprocket and the camshaft are changed by the change in the hydraulic pressure applied to the variable operation unit via the hydraulic control solenoid valve mounted on the oil supply unit with respect to the valve drive camshaft. A variable valve timing device that changes the phase angle is installed, and the supply of working oil from the oil supply unit of the variable valve timing device to the variable operating unit is performed not from the journal bearing side of the cylinder head but from the chain cover side. In a four-stroke engine that is configured to operate, the entire chain cover is separate from the cylinder head Together they are formed as members,
A mounting portion for mounting the oil supply portion of the variable valve timing device is formed integrally with the chain cover.

Further, in the chain cover structure for a four-stroke engine according to the first aspect of the present invention, as described in the second aspect, the camshaft penetrating the variable operation portion and protruding outward in the camshaft direction. The end portion is pivotally supported by an oil supply section of the variable valve timing device attached to the chain cover.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a chain cover structure for a four-stroke engine according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a V-type multi-cylinder twin-cam four-stroke engine according to an embodiment of the present invention in a state where an alternator and other accessories, pulleys and the like arranged around the engine body are removed. One of the two rows of cylinders is viewed from the outside of one end in the direction of the crank axis (hereinafter, this side is referred to as the front side).

In the engine body 1, although not shown, cylinder heads are respectively connected to upper ends of the cylinder block which are divided into V-shapes, and the upper portions of the cylinder heads are covered with cylinder head covers 2, respectively.
A crankshaft 4 is supported by a cylinder block and a crank bearing connected to a lower portion thereof, and an oil pan 5 is connected to a lower end of the cylinder block.

As shown in FIG. 1, a chain cover 6 integrally formed in a V-shape as a separate part from each cylinder head and cylinder block is provided over each cylinder head and cylinder block. A chain and a tensioner (both not shown) are provided so as to cover the front surface of the engine main body 1 in which the chain and the tensioner are arranged.
Valve timing is variable so that an oil transfer pipe 7 piped outside the chain cover 6 is connected to the vicinity of the front upper end of each cylinder head whose upper part is covered by the cylinder head cover 2 and whose front part is covered by the chain cover 6. The device 8 is installed.

FIGS. 2 and 3 show the internal structure near the front upper end of one of the cylinder heads in the engine body 1. FIG. 2 is a partial view taken along the line AA of FIG. FIG. 3 is a cross-sectional top view, and FIG. 3 is a cross-sectional side view taken along line BB of FIG.

At the upper end of the cylinder head of the engine body,
As shown in FIG. 2, an intake-side camshaft 11 for driving an intake valve and an exhaust-side camshaft 12 for driving an exhaust valve are installed at a distance from each other in parallel with the axial direction of the crankshaft. And the respective camshafts 11 and 12
The front end portions 11a and 12a of the cylinder head 3
From the front end journal bearing 3a.

A primary sprocket 14 on which a timing chain 13 from the crankshaft 4 is extended and a secondary chain on which a transmission chain 17 from a cam sprocket 16a of the intake camshaft 11 are extended. The sprocket 15 and the large diameter primary sprocket 14 are on the front side (outside in the cam shaft direction).
, And the secondary sprocket 15 having a small diameter is located on the rear side (inward in the cam shaft direction).
2 and the connecting pin 1
9 are integrally fixed.

A sprocket housing 16 is provided at the front end portion 11a of the intake camshaft.
Is inserted into the large-diameter portion of the front end portion 11a of the intake-side camshaft so as to be rotatable so as to straddle the primary sprocket 14.
6 at the rear end via a transmission chain 17 on the exhaust side camshaft 1.
A cam sprocket 16a interlocked with the second secondary sprocket 15 is integrally formed.

The front end portion 11a of such an intake side camshaft.
, The cam sprocket 16a and the intake camshaft 11
A variable valve timing device (VVT) 8 for changing the opening / closing timing of the intake valve according to the operating state of the engine by changing the phase of the cylinder head 3 includes the sprocket housing 16 as one of the constituent members. Is installed so as to penetrate the chain cover 6 that covers the front of the vehicle.

The variable valve timing device 8 is fixed to the chain cover 6 with bolts 33, also serving as a variable operating portion provided at the front end portion 11a of the intake camshaft and a cover member for covering the variable operating portion from outside. An oil transfer pipe 7 is connected to the main body 20 of the oil supply section, and the working oil supplied to the variable valve timing device 8 by the oil transfer pipe 7 is
Solenoid valve 2 for hydraulic control of oil supply section
According to the control of (1), the oil is sent to the variable operation section by one of the two oil passages 23 and 24 formed in the front end portion 11a of the intake camshaft.

The variable operation portion of the variable valve timing device 8 is integrally formed on an oil housing main body 26 formed by connecting three members with bolts 27 and rearward of the oil housing main body 26 by fastening together with the bolts 27. The sprocket housing 16 is fixed to the front end portion 11a of the intake camshaft, and is covered with the oil housing main body 26 and is integrally fixed to the front end portion 11a of the intake camshaft via the screw member 28. .

The oil housing main body 26 fixed to the front portion of the sprocket housing 16 is located on the front side of the primary sprocket 14 because the sprocket housing 16 is disposed so as to straddle the primary sprocket 14 of the exhaust camshaft 12. (Outside in the cam axis direction).

Although the relationship between the inner rotor 29 and the oil housing main body 26 is not shown in detail, a plurality of oils radially arranged around the axis of the camshaft 11 inside the oil housing main body 26 are shown. Each blade of the inner rotor 29 is housed in the chamber 30 as a partition plate, and one side formed by the blade in each oil chamber 30 is formed on the front end portion 11a of the intake-side camshaft. A structure conventionally known as a vane type variable operating portion, in which an oil passage 23 is communicated through an oil passage provided at a base portion of the inner rotor 29 and another oil passage 24 is communicated with the other side. belongs to.

According to such a vane type variable operating section, the operating oil from one oil passage 23
By operating the hydraulic pressure on one of the partitioned sides of each oil chamber 30,
The inner rotor 29 is rotated in one direction with respect to the oil housing main body 26 through its blades, and the hydraulic oil acts on the other side by the operating oil from the other oil passage 24 so that the inner rotor 29 is inverted. , Whereby the phase angle between the cam sprocket 16a fixed to the oil housing main body 26 and the cam shaft 11 to which the inner rotor 29 is fixed is changed.

As shown in FIGS. 4 (A), 4 (B) and 4 (C), an oil supply section for applying oil pressure to the oil housing main body 26 of the variable operation section as described above is provided.
0 for solenoid valve 21 for hydraulic control
And an oil filter 22 are integrally assembled, and the main body 20, which also serves as a cover member for covering the variable operation portion, supports the end of the intake side camshaft 11 (the front end of the front end portion 11a). 20a is recessed in the center of the inside thereof, and from the bearing 20a, oil for returning hydraulic oil leaked from between the oil supply portion and the front end portion 11a of the intake camshaft to the lower part of the engine body. A return passage 20b is formed, and a plurality of bolt holes 20d for attachment to the chain cover 6 are formed in a circumferential outer edge 20c of the main body 20.

On the other hand, the chain cover 6 to which the main body 20 of the oil supply unit is attached has the structure shown in FIG.
As shown in (B), a semicircular arch-shaped portion is integrally formed at the upper end, so that a circular window 32 having a diameter through which the variable operation portion of the variable valve timing device 8 can pass is opened at the center. A ring-shaped mounting portion 6a is integrally formed, and the front surface of the ring-shaped mounting portion 6a is a mating surface with the main body 20 of the oil supply unit to be mounted.

For mounting the oil supply unit main body 20 on the chain cover 6, first, the bearing 20 a of the oil supply unit main body 20 is connected to the intake side camshaft protruding outward from the circular window 32 of the chain cover 6. Front end part 11 of
a of the oil supply unit main body 20 with the front surface of the ring-shaped mounting portion 6a of the chain cover 6 and the bolt hole 20 from the front.
The two are fixed by bolts 33 through d.

At this time, by slightly increasing the size of each bolt hole 20d of the oil supply unit main body 20, even if the precision of each component is not high, the positioning of the bearing portion 20a with respect to the intake camshaft 11 can be ensured. In addition, the oil supply unit main body 20 can be securely attached to the ring-shaped attachment portion 6a of the chain cover 6.

The mounting portion 6 of the oil supply portion of the variable valve timing device 8 is attached to the chain cover 6 formed as a separate member from the cylinder head 3 as described above.
According to the four-stroke engine of the present embodiment in which the chain cover 6 is integrally formed, the chain cover 6 is
Since it can be freely removed from the engine body, the assembling workability when assembling the chain guide, the tensioner, and the like to the engine body is improved.

In the case of a V-type engine as in the present embodiment, a chain cover portion is previously integrated with both ends of the cylinder head 3 in the cam axis direction for each cylinder row divided into V-types. Even if it is not necessary to form the cylinder head 3 in the same direction, the cylinder head 3 can be arranged in the opposite direction in the cam axis direction and then shared, so that the length of the cylinder head 3 in the cam axis direction is unnecessary. There is no such thing as a long one.

Further, since the mounting portion for mounting the oil supply unit body 20 of the variable valve timing device 8 is formed integrally with the chain cover 6 as a ring-shaped mounting portion 6a, the number of parts can be reduced. In addition, when the oil supply unit main body 20 is attached to the attachment portion 6a of the chain cover 6, the mating surfaces of the two are aligned so that the sealing performance of the portion can be improved.

Further, in the present embodiment, the front end portion 11a of the camshaft on the intake side to which the heavy oil housing main body 26 is attached is projected forward (outward in the cam shaft direction) from the oil housing main body 26. Since the front end of the portion 11a is supported by the bearing 20a of the oil supply unit main body 20, the load on the front end 11a during rotation of the camshaft 11 is reduced, and the front end 11a of the camshaft 11 is As a result, it is possible to form the cylinder head and the combustion chamber more compactly.

The embodiment of the chain cover structure of the four-stroke engine according to the present invention has been described above. However, the present invention is not limited to, for example, a V-type engine. Needless to say, the present invention is not limited to the specific structure as shown in the above embodiment, for example, it can be implemented by installing the variable valve timing device 8 for the valve 12.

[0032]

According to the above-described chain cover structure of the four-stroke engine of the present invention, the workability when assembling the chain guide and the tensioner can be improved, and the cylinder manufactured with the same structure can be obtained. Even when the head is arranged in the opposite direction and shared, it is not necessary to make the length of the cylinder head in the cam axis direction unnecessarily long, and the number of parts for mounting the variable valve timing device is reduced. And the sealing performance at the mounting portion of the variable device can be improved.

[Brief description of the drawings]

FIG. 1 is a front view partially showing an engine body of a V-type multi-cylinder engine according to an embodiment of a chain cover structure of a four-cycle engine of the present invention.

FIG. 2 is a partial cross-sectional top view of the engine body shown in FIG. 1 along the line AA.

FIG. 3 is a cross-sectional side view of the engine body shown in FIG. 1 taken along line BB.

4 (A) is a front view, FIG. 4 (B) is a cross-sectional side view taken along the line CC of FIG. (C) The sectional side view along the DD line of FIG.

5 (A) is a front view showing a mounting portion for mounting an oil supply unit of the variable valve timing device in the chain cover of the engine body shown in FIG. 1, and FIG. 5 (B) is a view taken along line EE in FIG. FIG.

[Explanation of symbols]

1 4-cycle engine (engine body) 2 Cylinder head cover 3 Cylinder head 3a Journal bearing (of cylinder head) 6 Chain cover 6a Mounting part (for mounting oil supply part) 8 Variable valve timing device 11 Camshaft (intake side) 16a Cam sprocket (intake side) 20 Oil supply section (body) of variable valve timing device 21 Solenoid valve 26 Oil housing body (variable operation section)

Claims (2)

(57) [Claims] 1. A solenoid for hydraulic control mounted on an oil supply portion with respect to a cam shaft for driving a valve, on an outer side of an upper portion of a cylinder head which is covered with a chain cover and an upper portion is covered with a cylinder head cover. A variable valve timing device that changes the phase angle between the cam sprocket and the camshaft by changing the hydraulic pressure applied to the variable operation unit via the valve is installed, and the operation of the variable valve timing device from the oil supply unit to the variable operation unit is performed. In a four-stroke engine in which oil is supplied not from the journal bearing portion side of the cylinder head but from the chain cover side, the entire chain cover is formed as a member separate from the cylinder head. At the same time, the installation for attaching the oil supply section of the variable valve timing A chain cover structure for a four-stroke engine, characterized in that an attached portion is formed integrally with the chain cover. 2. An end of a camshaft penetrating the variable operation portion and protruding outward in the camshaft direction is axially supported by an oil supply portion of a variable valve timing device mounted on a chain cover. The chain cover structure for a four-stroke engine according to claim 1.