JP2766684B2 - Overhead cam engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an overhead cam engine in which a rotor unit of a distributor is coaxially connected to an end of a camshaft.

2. Description of the Related Art For example, a multi-cylinder engine for an automobile includes a distributor that distributes a high voltage generated in an ignition coil to spark plugs of each cylinder at a predetermined timing. Conventionally, there has been known an engine in which a rotor unit of the distributor is coaxially connected to a cam shaft provided on a cylinder head, and the distributor is driven by the cam shaft.

When the distributor is driven by the camshaft, the distributor may be provided at the end of the camshaft on the timing chain side.

At this time, the timing chain is covered with a chain cover covering one end of the cylinder head, and since the chain cover is also connected to the head cover covering the cylinder head, the rotor unit is combined with the chain cover and the head cover. It is led out through the part. The outwardly extending portion of the rotor unit is covered by a substantially cylindrical distributor housing, and the distributor housing is connected to the chain cover and the head cover.

[Problems to be Solved by the Invention] However, according to this conventional configuration, since the distributor housing straddles the head cover and the chain cover, if the dimensional accuracy of these three parts is not improved, a gap is formed in the joint portion of the distributor housing. There is a problem that it takes time and effort to attach the distributor housing as well as the dimensional control of each part.

In addition, even if the penetrating portion of the rotor unit is sealed, it is necessary to interpose a sealing material between the rotor unit and both covers and between the rotor unit and the distributor housing. There are problems such as complication.

The present invention has been made based on such circumstances, and the distributor housing can be easily mounted without straddling between the two covers, and the sealing structure of the penetrating portion of the rotor unit can be simplified, and The axial dimension of the distributor can be shortened,
The objective is to provide a compact overhead cam engine.

Means for Solving the Problems Therefore, in the present invention, the camshaft and the crankshaft of the cylinder head are interlocked via the power transmission means, and the power transmission means is put on one end face of the cylinder head. An overhead cam type engine in which a head cover is attached between the cover and the cylinder head, and a rotor unit of a distributor is coaxially connected to an end of the cam shaft on the cover side. A boss through which the rotor unit penetrates via a seal member, and a periphery of the rotor unit penetrating through the boss and extending to the outside is covered with a distributor housing. Are integrally formed.

[Operation] According to this configuration, since the distributor housing is formed integrally with the cover, the distributor housing does not straddle the mating portion of the cover and the head cover. For this reason, there is no possibility that a gap is formed between the distributor housing and the cover or the head cover, and accordingly, high-precision dimensional control is not required, and the distributor housing can be easily attached.

In addition, since the rotor unit penetrates only the cover integral with the distributor housing, when sealing the penetrating portion of the rotor unit, the sealing member does not extend between the two parts, and Can be simplified.

Further, by integrating the cover and the distributor housing, the connection structure between them can be omitted. Therefore, the axial dimension of the distributor can be reduced, and the engine can be made more compact.

Embodiment An embodiment of the present invention will be described below with reference to the drawings applied to a V-type multi-cylinder engine.

The cylinder block indicated by reference numeral 1 in FIG. 3 includes a lower case 3 that supports the crankshaft 2. On the upper surface of the lower case 3, a pair of cylinder rows 4 are erected in a V-shape. As shown in FIG. 4, one of the cylinder rows 4 has a cylinder body 5 in which a plurality of cylinders are arranged in the axial direction of the crankshaft 2, and is covered by an upper surface of the cylinder body 5. A cylinder head 6 is provided, and the cylinder body 5 is integrated with the lower case 3.

The upper surface of the cylinder head 6 is covered by a head cover 7. These cylinder head 6 and head cover 7
A valve operating chamber 8 is formed between the two. In the valve operating chamber 8,
An intake camshaft and an exhaust camshaft 11 are housed, and one end of each of the camshafts 10 and 11 has a timing sprocket 1
2 are installed.

A bracket is provided on the front surface of one end of the cylinder head 6.
13 is bolted. Bracket 13 has intermediate shaft 14
A primary sprocket 15 is supported on the outer periphery of the intermediate shaft 14. The number of teeth of the primary sprocket 15 is larger than the number of teeth of the driving sprocket 16 provided at one end of the crankshaft 2.
Between them, a primary timing chain 17 is extended.

A secondary sprocket 18 is formed integrally with the primary sprocket 15. The number of teeth of the secondary sprocket 18 is smaller than the number of teeth of the primary sprocket 15 and the timing sprocket 12, and these timing sprockets are used.
A secondary timing chain 19 is bridged between the secondary sprocket 18 and the secondary sprocket 18.

Therefore, the rotational speed of the crankshaft 2 is transmitted to the camshafts 10 and 11 after being reduced in two stages between the crankshaft 2 and the intermediate shaft 14 and between the intermediate shaft 14 and the camshafts 10 and 11. In the case of the present embodiment, the two timing chains 17 and 19 constitute power transmission means from the crankshaft 2 to the camshafts 10 and 11.

This power transmission means is provided by the timing chains 17, 19
However, the present invention is not limited thereto, and may be, for example, a timing belt or a timing gear.

An aluminum alloy chain cover 20 is bolted to the front surface of one end of the cylinder block 1 and the cylinder head 6. The chain cover 20 forms a chain passage 21 between the cylinder body 5 and the cylinder head 6, and covers the timing chains 17, 19 from the front of the engine. And the chain cover
The upper end of 20 is connected to the head cover 7, which closes the upper end of the chain passage 21.

By the way, a distributor for distributing a high voltage generated in an ignition coil to a spark plug (not shown) of each cylinder is provided in a cylinder head 6 of one cylinder row 4.
24 are provided. The distributor 24 has a configuration similar to that of a conventionally known one, and includes a rotor unit 25 coaxial with the intake camshaft 10 as shown in FIG.

The rotor unit 25 includes a rotor shaft and a rotor 27. The rotor shaft 26 is located at one end of the intake camshaft 10 on the timing sprocket 12 side, and the tip of the rotor shaft 26 is connected to a boss 28 of a rotor 27 via a pin 29. The rotor shaft 26 and the rotor 27 are fixed to one end surface of the intake camshaft 10 via bolts 30, and are driven to rotate integrally with the intake camshaft 10.

A boss 31 is formed on the mating surface 20a of the chain cover 20 with the head cover 7 so as to project in an arc toward the head cover 7 as shown in FIGS. The boss portion 31 is provided for the intake camshaft 10 of one of the cylinder rows 4.
The thickness is formed thicker than that of the chain cover 20. And the boss part 31
Is formed with a through hole 32 through which the rotor shaft 26 passes.
An oil seal 33 that seals a penetrating portion of the rotor shaft 26 is held on the inner surface of the through hole 32.

The rotor 27 at the tip of the rotor shaft 26 is led out of the chain cover 20, and the periphery of the rotor 27 is covered by a distributor housing 35. The distributor housing 35 has a substantially cylindrical shape with an opening on the side opposite to the cylinder head 6, and the end on the cylinder head 7 side is continuous with the boss portion 31 of the chain cover 20 and is integrated with the chain cover 20. Have been.

The opening of the distributor housing 35 is covered with a cap 36 made of synthetic resin. The cap 36 is provided with a number of terminals (not shown) corresponding to the number of cylinders and the center carbon in contact with the rotor 27, and the periphery of the rotor 27, the center carbon and the terminals are covered with a magnetic shield cap 37. I have.

A ring-shaped shutter 38 is fixed to the rotor 27 via a screw 39. A cam sensor 40 for detecting the rotation angle of the intake camshaft 10 via the shutter 38 is provided radially outside the shutter 38. Is provided.

According to such a configuration, the primary timing chain 17
And chain cover to cover the secondary timing chain 19
Since the distributor housing 35 is integrally formed with the cylinder 20, the distributor housing 35 does not straddle the joining portion of the chain cover 20 and the head cover 7 even though the distributor 24 is provided on the cylinder head 6.

For this reason, there is no possibility that a gap is formed between the distributor housing 35 and the head cover 7, and accordingly, high-precision dimensional control is not required, and the distributor housing 35 can be easily attached.

In addition, since the rotor shaft 26 only penetrates the boss 31 of the chain cover 20, the oil seal 33 that seals the penetrating portion of the rotor shaft 26 does not extend between the two parts, and the rotor shaft 26 The seal structure can be simplified.

For this reason, in addition to integrating the distributor housing 35 with the chain cover 20, the number of parts can be reduced, and the number of assembling steps can be reduced, and the cost can be reduced.

Further, since the chain cover 20 and the distributor housing 35 are integrated, the connection structure between them can be omitted. For this reason, the axial dimension of the distributor 24 and, consequently, the amount of protrusion of the distributor 24 from the chain cover 20 can be reduced, which also has the advantage of contributing to a compact engine.

Note that the overhead cam engine according to the present invention
The invention is not limited to a V-type engine having a V-shaped cylinder arrangement, but may be, for example, an in-line multi-cylinder engine.

In the above embodiment, the cylinder head is provided with two camshafts for intake and exhaust. However, for example, a so-called SOHC type engine in which an intake cam and an exhaust cam are provided on one camshaft. This can be similarly performed.

[Effects of the Invention] According to the present invention described in detail above, the distributor housing does not straddle the joining portion of the cover and the head cover, so that high-precision dimensional management is not required, and
This distributor housing can be easily mounted.

In addition, since the rotor shaft only penetrates through the cover, the sealing member for sealing the penetrating portion of the rotor shaft does not extend between the two parts, and the sealing structure of the rotor shaft can be simplified. Therefore, in addition to the fact that the distributor housing is integrated with the cover, the number of parts can be reduced, and accordingly, the number of assembling steps can be reduced and the cost can be reduced.

Furthermore, since the connection structure between the cover and the distributor housing is not required, there is an advantage that the axial dimension of the distributor can be reduced, which contributes to downsizing of the engine.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention. FIG. 1 is a cross-sectional view of a mounting portion of a distributor, FIG. 2 is a view taken in the direction of the line II in FIG. 1, and FIG. Figure,
FIG. 4 is a front view showing a driving path of the cam shaft. 2 ... Crank shaft, 6 ... Cylinder head, 7 ... Head cover, 10,11 ... Cam shaft (intake cam shaft, exhaust cam shaft), 17,19 ... Power transmission means (primary timing chain, Next timing chain), 20 ... cover (chain cover), 24 ... distributor, 25 ... rotor unit, 31 ... boss, 33 ... seal member (oil seal), 35 ... distributor housing.

Claims (1)

(57) [Claims] A camshaft and a crankshaft of a cylinder head are interlocked via a power transmission means, and the power transmission means is covered with a cover covering one end surface of the cylinder head. A head cover is attached between the camshaft and the end of the camshaft on the cover side, and the rotor unit of the distributor is coaxially connected to the end of the camshaft. The rotor unit is attached to the cover via a seal member. A boss portion that penetrates the boss portion is provided, and the periphery of the rotor unit that extends outward through the boss portion is covered with a distributor housing, and the distributor housing and the cover are integrally formed. Overhead cam type engine.