JP3327322B2 - 4 cycle engine with variable valve timing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke engine having a DOHC type valve system, and more particularly to a variable valve timing device (VVT) for a cam shaft for driving one of an intake side and an exhaust side. For a four-stroke engine.

[0002]

2. Description of the Related Art A four-stroke engine having a DOHC type valve system, that is, a valve driving camshaft driven via a timing chain by rotation of a crankshaft is provided on an intake side and an exhaust side above a cylinder head. In each of the four-stroke engines provided, the cam sprocket and the camshaft are changed by a change in hydraulic pressure provided through a solenoid valve for controlling hydraulic pressure in order to change the opening and closing timing of the intake and exhaust valves according to the operating state of the engine. A variable valve timing device (VVT) that changes the phase angle of the camshaft is installed near the end of one of the valve driving camshafts.

In a four-stroke engine equipped with such a variable valve timing device, a timing chain from a crankshaft is used in order to reduce the axial center distance between both camshafts and to make the cylinder head and the combustion chamber compact. One transmission chain is extended over the primary sprocket of one camshaft, and another transmission chain is extended over the secondary sprocket provided inside the primary sprocket of the camshaft and the cam sprocket of the other camshaft. It has been conventionally considered to mount a variable operation portion of a variable valve timing device on the outer side of a primary sprocket of a shaft in a cam axis direction.

[0004]

By the way, a conventional four-cycle system in which the variable operating portion of the variable valve timing device is mounted outside the primary sprocket as described above and the other camshaft is transmitted by the secondary sprocket. As for the engine, by making the secondary sprocket (and the cam sprocket of the other camshaft) smaller than the primary sprocket, the center distance between the two camshafts can be shortened. It becomes possible to configure compactly.

However, since the variable operation portion of the variable valve timing device is mounted on the primary sprocket over which the timing chain is wound, when the phase of the camshaft with respect to the primary sprocket is changed, the secondary sprocket rotates with it. Since the phase of the other camshaft can be similarly changed via the sprocket, there is a problem that it is not possible to independently control only one of the valve timings on the intake side and the exhaust side.

[0006]

According to the present invention, a cam shaft for driving a valve is provided on each of an intake side and an exhaust side to solve the above-mentioned problems. The timing chain from the crankshaft is wrapped around the primary sprocket fixed to one camshaft, and crosses over the secondary sprocket fixed to the one camshaft and the cam sprocket mounted on the other camshaft. In a four-stroke engine in which another transmission chain is bridged, the valve timing is varied to change the phase angle between the cam sprocket and the camshaft by changing the hydraulic pressure applied to the oil housing body via a hydraulic control solenoid valve. A device is mounted on the other camshaft and mounted on the other camshaft. Le housing body, than primary sprocket of one of the camshaft the disposed outside the cam axis, the sprocket Howe in the oil housing body
The front of the jing is secured and the sprocket housing
At the rear end, the cam sprocket of the other camshaft is integrated
And the sprocket housing is formed with the one cam
It is characterized by being arranged so as to straddle the primary sprocket of the shaft .

In a four-stroke engine provided with the variable valve timing device according to the first aspect of the present invention, as described in the second aspect, the cam shaft on which the oil housing body is mounted is connected to the oil housing. The camshaft is supported at the end of the camshaft penetrating the main body and protruding outward in the camshaft direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a four-cycle engine provided with a variable valve timing device 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 the V-shaped upper ends of the cylinder blocks, 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 on 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 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 so as to serve also as a variable operation portion provided at the front end portion 11a of the intake camshaft and a cover member for covering the variable operation 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 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), the oil supply section for applying oil pressure to the oil housing main body 26 of the variable operation section as described above.
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, 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 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 accuracy 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.

As described above, the variable valve timing device 8
According to the four-stroke engine of the present embodiment, even when the phase of the intake camshaft 11 with respect to the cam sprocket 16a is changed by the variable valve timing device 8, the exhaust camshaft 12 is not affected at all. Therefore, only one (intake side) valve timing can be controlled independently.

Further, since the oil housing main body 26 is arranged on the outer side (front side) of the primary sprocket 14 having a large diameter in the cam axis direction, the secondary sprocket 15 (and the cam sprocket 16a of the other cam shaft 11) is reduced in diameter. As a matter of course, even if the distance between the two camshafts 11 and 12 is reduced, the oil housing body 26 and the primary sprocket 14 do not interfere with each other, and the distance between the two camshafts 11 and 12 is made as short as possible. The cylinder head 3 can be made narrow and compact, and the combustion chamber can be made compact.

Further, the camshaft front end portion 11a on the intake side to which the heavy oil housing body 26 is mounted is located on the front side (outward in the cam shaft direction) of the oil housing body 26.
The front end portion 11a of the oil supply portion main body 20 is supported at the front end portion of the front end portion 11a protruding from the oil supply portion main body 20 so that when the camshaft 11 rotates, the front end portion 11a
, The front end portion 11a of the camshaft 11 can be made thinner, whereby the distance between the center axes of the camshafts 11 and 12 can be further reduced, and the cylinder head And the combustion chamber can be made more compact.

The embodiment of the four-stroke engine provided with the variable valve timing apparatus according to the present invention has been described above. However, the present invention is not limited to, for example, a V-type engine. By installing the variable valve timing device 8 with respect to the camshaft 12, it is also possible to configure and implement such that only the intake side valve timing is controlled independently. Needless to say, the present invention is not limited to such a specific structure.

[0030]

According to the four-cycle engine provided with the variable valve timing device of the present invention as described above,
Only one of the intake-side and exhaust-side valve timings can be controlled independently, and the cylinder center and the combustion chamber can be controlled by minimizing the axial distance between the intake-side camshaft and the exhaust-side camshaft. It can be made compact.

[Brief description of the drawings]

FIG. 1 is a diagram showing a valve equipped with a variable valve timing device of the present invention
FIG. 1 is a front view partially showing an engine body of a V-type multi-cylinder engine according to an embodiment of a cycle engine.

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]

 Reference Signs List 1 4 cycle engine (engine body) 4 Crankshaft 8 Variable valve timing device 11 Camshaft (intake side) 12 Camshaft (exhaust side) 13 Timing chain 14 Primary sprocket (exhaust side) 15 Secondary sprocket (exhaust side) 16a Cam sprocket (Intake side) 17 Transmission chain 21 Solenoid valve 26 Oil housing body

Claims (2)

(57) [Claims] 1. A cam chain for driving a valve is provided on each of an intake side and an exhaust side, and a timing chain from a crank shaft is wrapped around a primary sprocket fixed to one of the cam shafts. In a four-stroke engine in which another transmission chain extends over a secondary sprocket fixed to the camshaft and a cam sprocket mounted on the other camshaft, an oil housing is provided via a solenoid valve for hydraulic control. A variable valve timing device that changes the phase angle between the cam sprocket and camshaft by changing the hydraulic pressure applied to the body
Together are placed against said other camshaft, oil housing body mounted on said other cam shaft is disposed on the outer camshaft direction than the primary sprocket on one of the cam shaft said, the oil housing Spro on body
The front part of the bracket housing is fixed, and the sprocket
At the rear end of the housing, a cam sprocket of the other cam shaft
Are integrally formed, and the sprocket housing is
Straddle the primary sprocket of one camshaft
A four-stroke engine provided with a variable valve timing device arranged . 2. A camshaft to which an oil housing main body is mounted is supported by an end of the camshaft that penetrates through the oil housing main body and protrudes outward in a camshaft direction. A four-stroke engine provided with the variable valve timing device according to claim 1.