JPS62131956A - Four cycle engine - Google Patents

Abstract

PURPOSE:To enhance the rigidity of cylinder head cover, by dividing the cylinder head cover into a flask-like cam casing surrounding only an area in which the slidable sections of cam surfaces and valve members are alone positioned, and an upper cover fastened onto the mating surface of the cam casing through the intermediary of a packing by means of bolts. CONSTITUTION:A cylinder head cover 11 is divided into a rectangular flask-like cam casing 29 superposed on the upper surface of a cylinder head 4 through the intermediary of a first packing 28, and a shallow pan-like upper cover 31 superposed on the upper surface of the above-mentioned cam casing 29 through the intermediary of a second packing 30. The cam casing 29 surrounds only an area in which the slidable sections of the cam surfaces 14 of cam shafts 13, 14 and a valve lifter 18 are positioned. The upper cover 31 covers integrally the upper surface opening section of the cam casing 29, and is formed in the center section thereof with four holes 38 through which bolts are inserted to fasten the upper cover 31 to boss sections 37 of the cam casing 37.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overhead cam type four-stroke engine.

[Prior art]

In this type of engine, the head cover that covers the valve train such as the camshaft is relatively frequently removed and removed for valve clearance inspection and adjustment. When installing, it is required to seal the oil securely.

By the way, in an engine in which the cylinder arrangement is V-shaped and a surge tank is arranged on each cylinder head, as seen in, for example, Japanese Patent Application Laid-Open No. 60-81458, the surge tank and the head force I- come close to each other. Therefore, the space around the head cover becomes narrow, and workability when removing the head cover becomes a problem. That is, if the surge tank and the intake pipe connected to the surge tank were to be attached and detached every time the valve clearance was inspected or adjusted, the work would be very time-consuming and the engine would be extremely difficult to maintain.

Therefore, as seen in, for example, Japanese Patent Application Laid-Open No. 58-51250, the head cover is made up of an annular member that is superimposed on the cylinder and a dish-shaped member that is removably bolted to the top surface of this annular member. I might consider splitting it up.

[Problem that the invention seeks to solve]

However, in the configuration of this prior art, if the number of bolts tightening the dish member is reduced in order to make it easier to attach and remove the dish member, the dish member has a shallow dish shape and is inherently rigid. Since there is no such thing, it becomes easily distorted.

Therefore, the surface pressure applied to the annular member and the base surface is not uniform, resulting in problems such as oil leakage and smearing.

[Means for solving problems]

Therefore, in the present invention, the cam 1II is attached to the end of the camshaft.
A sprocket for I'4II movement is provided, and a Rad cover is superimposed on the cylinder to cover the cam φ peak, and the area where the sliding contact between the cam surface of the camshaft and the valve operating member is located. It is characterized by being divided into a frame-shaped cam case that surrounds the cam case, and a dish-shaped upper cover that is removably bolted to the mating surface of the cam case via a gasket.

[Effect]

According to this configuration, since the area where the head cover covers the valve train is narrowed, both the cam case and the upper cover can be downsized, and the rigidity of the upper cover and the cam case is improved accordingly.

Therefore, due to this increased rigidity, even if the number of bolts tightening the upper cover is reduced, the upper cover will not be distorted, and the surface pressure applied to the base surface with the cam case will be uniform, allowing the gasket to adhere tightly to the base surface without any gaps. do. For this reason, it is possible to further improve the ease of attaching and removing the upper cover, and to ensure sufficient sealing performance, thereby reliably preventing oil leakage and smearing.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4, in which the invention is applied to a V-type six-cylinder engine for an automobile.

In Fig. 2, on the crankcase indicated by the symbol l,
A pair of cylinder rows 2.2 are arranged in a V-shape. The cylinder row 2.2 has a cylinder head 4 on a cylinder block 3 integrated with the crankcase l, and the cylinder head 4 has three cylinders (not shown) provided in the cylinder block 3. ), two intake ports 5 and two exhaust ports 6 are opened. The intake ports 5 are opened on the opposing faces of the cylinder rows 2.2, and the open ends thereof are connected via intake pipes 7 to surge tanks 8.8 disposed directly opposite each cylinder row 2, 2. ing.

The cylinder head 4 supports an intake valve 9 that opens and closes the intake port 5 and an exhaust valve IO that opens and closes the exhaust port 6.

A head cover 11 is fitted onto the upper surface of the cylinder head 4, and the cylinder head 4 and the head cover 1
An intake camshaft 13 and an exhaust camshaft 14 are disposed within the valve operating chamber 12 formed between the intake camshaft 13 and the exhaust camshaft 14 . An intake cam 15 that opens and closes the intake valve 9 and an exhaust cam 6 that opens and closes the exhaust valve 10 are separately formed on the outer periphery of both of these cams i [1113, 14, with an interval in the axial direction. The cam surfaces 17 of these cams 15, 16 are in sliding contact with a valve lifter 18 connected to the intake valve 9 and the exhaust valve 10 to directly open and close the intake valve 9 and the exhaust valve 10. And the intake camshaft 13
One end is led out to the outside of the cylinder head 4, and a toothed belt 21 that transmits power from a crankshaft 20 is wound around a drive sprocket 19 fixed to this lead-out end. Further, one end of the other end of the intake camshaft 13 and the exhaust camshaft 14 located on the same side as this other end are also led out to the outside of the cylinder head 4, and both of these camshafts 1
3.14 is the interlocking sprocket 2 fixed to each lead-out end
2. By winding the toothed belt 24 between the
are linked to each other.

Note that both camshafts 13 and 1 are provided on the upper surface of the cylinder head 4.
A bearing holder 25 rotatably supported at three locations along the axial direction of the bearing holder 25 is fixed via bolts 26, and
On the outside of the cylinder head 4, the camshaft 13.
A holder portion 27 is formed to cover the outwardly leading portion of the holder 14 from below.

By the way, as shown in FIG. 1, the head cover 11 includes a cam case 29 in the shape of a rectangular frame that is superimposed on the upper surface of the cylinder head 4 via a first gasket 28.
and a shallow dish-shaped upper cover 31 which is overlapped on the upper surface of the cam case 29 with a second gasket 30 interposed therebetween. As shown in FIGS. 3 and 4, the cam case 29 surrounds only the area where the sliding contact portion between the cam surface 17 of each camshaft 13.14 and the valve lifter 18 is located. The end of 14 is the cam case 2
It passes through the side of 9. A housing portion 3 that faces and matches the holder portion 27 is provided on the side surface of the cam case 29.
2 is formed, and an oil seal (not shown) and a bearing 33 that pivotally supports the lead-out portions of the camshafts 13 and 14 are interposed between the holder portion 27 and the housing portion 32. Further, a boss portion 37 having a spark plug insertion hole 3B is provided inside the cam case 29, and this boss portion 37 is integrated with the cam case 29 via a rib wall 43. And, such a cam case 29 is
The plurality of flange portions 34 provided on the outer circumference and the boss portion 37 are fixed to the cylinder head 4 by tightening them with bolts 35, and this fixation allows the first gasket 28 to be placed between the cylinder head 4 and the cam case 29. The base is clamped to the base, and this base is sealed liquid-tight.

The upper cover 31 integrally covers the upper opening of the cam case 29, and the base of the upper cover 31 and the cam case 29 is located above the axial center of the cam shaft 13.14. The above-mentioned surge tank 8 is located close to and directly above the. and,
This upper cover 31 has a bolt 39 inserted from one side into four insertion holes 38 formed at intervals in the center thereof, and the insertion end of the bolt 39 is inserted into a screw provided in the boss portion 37. By screwing into the hole 40, the tightening is removably fixed on the cam case 29, and this fixing allows the second gasket 30 to be attached to the cam case 29 and the upper cover 3.
1 and the entire surface thereof to seal this table surface liquid-tightly.

Note that a groove 41 is formed continuously in the circumferential direction on the base surface of the cam case 29 and the base surface of the upper cover 31, and the protrusions provided on the first and second gaskets 28 and 30 are formed in the groove 41. 42 is fitted.

In such a configuration, the cam surface 17 and the valve lifter 1
To adjust the clearance between the upper cover 31 and the cam case 8, loosen and remove the four bolts 39 tightening the upper cover 31, and remove the upper cover 31 from above the cam case 29. In this case, the upper cover 31 not only has a shallow dish shape, but also has a base surface with the cam case 29 located above the axial center of the cam shaft 13.14, so the surge tank 8
It can be removed in the narrow space between the

When this upper cover 31 is removed, the sliding contact portion between the cam surface 17 of each camshaft 13 and 14 and the valve lifter 18 is exposed through the upper surface opening of the cam case 29, so the clearance adjustment work can be performed by removing the surge tank 8. You can do it without any trouble.

By the way, in the head cover 11 having the above structure, the cam case 29 does not cover the entire camshaft 13.14, but only surrounds the area where the sliding contact portion between the cam surface 17 and the valve lifter 18 exists. The area surrounding the valve train becomes narrower. Therefore, the upper cover 31 including the cam case 29 is made smaller and the rigidity of each part is improved, so even if the number of bolts 39 tightening the upper cover 31 is reduced, the upper cover 31
The cam case 29 is not distorted, and the surface pressure applied to the base surface with the cam case 29 becomes uniform in the circumferential direction.

Therefore, the number of bolts 39 is reduced.
The work of attaching and detaching the upper cover 31 can be easily done, and the work does not require much effort. At the same time, as the above-mentioned surface pressure becomes uniform, the second gasket 30 reliably comes into close contact with the base surfaces of the cam case 29 and the upper cover 31 without any gaps, so that sufficient sealing performance can be ensured and oil can be removed. Leakage and bleeding can be reliably prevented.

Further, in the case of this embodiment, the bottom surface of the valve chamber 12 is inclined downward as it advances toward the outer exhaust camshaft 14 side due to the V-shaped arrangement of the cylinder rows 2, 2. In this structure, the base surfaces of the cam case 29 and the upper cover 31 are located above the axial centers of the cam shafts 13 and 14, so that the oil in the valve train chamber 12 is The pool gets deeper. Therefore, even if the upper cover 31 is removed for clearance adjustment, the oil accumulated in the valve train chamber 12 is difficult to flow out, which prevents wasted oil consumption and prevents oil from staining the cylinder head 4. It can be kept to a minimum.

Note that the present invention is not limited to the first embodiment described above, but, for example, the second embodiment of the present invention shown in FIGS.
As in the embodiment, the cam case 29 and the bearing holder 25 inside the cam case 29 may be connected and integrated by the rib wall 51, and a sealing material may be applied to the entire surface of the base of the cam case 29 and the cylinder head 4.

According to this configuration, not only the same effects as those of the first embodiment, but also the rigidity of the bearing portion of the camshaft 13, 14 are improved, so that the noise from the valve train can be suppressed.

Furthermore, the engine according to the present invention is not limited to a DOHC engine in which an intake camshaft and an exhaust camshaft are provided separately, but also a 5OHC engine in which an intake cam and an exhaust cam are provided on a single camshaft. Moreover, the cylinder arrangement is not limited to the V-shape, but may be a multi-cylinder series arrangement.

【Effect of the invention〕

According to the present invention described in detail above, the rigidity of the upper cover that covers the cam case is improved, so the number of bolts that tighten the upper cover can be reduced, and the upper cover can be more easily attached and detached. At the same time, the surface pressure applied to the base surfaces of the cam case and upper cover becomes constant, and the gaskets come in close contact with the base surfaces without any gaps, ensuring sufficient sealing performance and ensuring no oil leaks or smearing. It has the advantage of being preventable.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention.
The figure is a cross-sectional view of the cylinder head, Figure 2 is a side view with a partial cross section of the entire engine, Figure 3 is a plan view, Figure 4 is a plan view with the upper cover removed, Figures 5 and 6. 5 shows a second embodiment of the present invention, FIG. 5 is a sectional view of the cylinder head, and FIG. 6 is a plan view of the cam case. 4... Cylinder head, 9. to...Valve (intake valve, exhaust valve), 11...Head cover, 13
．． 14...Camshaft (intake camshaft, exhaust camshaft),
17...Cam surface, 18...Valve train member (valve lifter), 19.22° 23...Sprocket, 29...
・Cam case, 30... Packet skin (second packkin)
, 31... Upper cover, 39... Bolt.

Claims (1)

[Claims] In a 4-cycle engine in which a camshaft for opening and closing valves is disposed between a cylinder head and a head cover fitted over the cylinder head, a sprocket for driving the camshaft is provided at the end of the camshaft. A head cover that covers the camshaft is attached to a frame-shaped cam case that overlaps the cylinder head and surrounds only the area where the sliding contact between the cam surface of the camshaft and the valve operating member is located, and a frame-shaped cam case on the mating surface of this cam case. A four-stroke engine that is divided into a dish-shaped upper cover that is removably bolted to the top through a packing.