JPH0220444Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the structure of a cylinder head, and more specifically, to a cylinder head in which a cam cap mating surface and a head cover mating surface are flush and continuous. It is related to.

[Conventional technology]

Some engines for automobiles have a cylinder head attached to a cylinder block, and a camshaft provided above the head to open and close intake valves and exhaust valves.
Since the camshaft rotates by transmitting the rotation of the crankshaft, one end of the camshaft is supported on the cylinder head and protrudes to the side of the head, and a pulley for tensioning the timing belt is attached to it. . Such a camshaft is located between the cylinder head and the head cover, and its bearing surface is recessed in a semicircular shape from the head cover mating surface, and a cam cap is placed over each cam bearing. .

As mentioned above, since the camshaft protrudes to the side of the cylinder head, the bearing load on the bearing surface in the vicinity of the protrusion inevitably becomes large, making it a bearing part that is more important than other parts that support the camshaft and has high lubricity. This is required. However, the cam bearing portion is necessarily located at the end of the cylinder head close to the mating surface of the cylinder head and the head cover. Moreover, the gasket interposed on the head cover mating surface has an arch shape that straddles the camshaft at the position where it intersects with the camshaft, and the gasket surface pressure tends to be low at the base of the arch. The lubricating oil from the bearing will leak from the small gap in the area where the surface pressure is low.

For example, Japanese Utility Model Application Publication No. 59-58709 describes a structure in which a cam cap mating surface of a cam bearing portion is adjacent to a head cover mating surface. The cylinder head is provided with a guide groove that is continuous with the semicircular arc-shaped bearing surface and opens to prevent lubricating oil from the cam bearing from leaking out of the head. Therefore, the lubricating oil on the bearing surface is guided from the guide groove to the return hole of the cylinder head.

This is an engine with a single camshaft, and the cam bearing is located at the center of the cylinder head. Therefore, if we focus on one of the pair of cam cap mating surfaces formed on both sides of the semi-circular recess of the cam bearing, one side of the four sides forming the periphery of the mating surface will be connected to the head cover mating surface. , the other three sides have edges and are discontinuous. This is because the cam cap mating surface is located at the center and is not provided near the corner of the cylinder head where the head cover mating surface extending back and forth and the head cover mating surface extending left and right intersect on the top surface of the cylinder head. . That is, this is based on the fact that the head cover is connected only to the head cover mating surface extending in a direction perpendicular to the camshaft, and is not continuous to the head cover mating surface extending parallel to the camshaft.

By the way, if a liquid sealant is applied to such a cam cap mating surface for the reason explained later,
When the cam cap is placed on the cam cap to hold down the liquid sealant, the liquid sealant inevitably flows out in the direction of least resistance. Therefore, since the amount of overflow toward and from the discontinuous edge increases, the amount of outflow toward the side that connects to the head cover mating surface tends to be smaller than the amount of outflow toward the edge. .

Therefore, as long as the liquid sealant behaves like this, the amount of liquid sealant that enters the gasket attached to the head cover mating surface will decrease, and the sealing function of the gasket will deteriorate due to the ingress of the liquid sealant. This does not pose much of a problem with the cam bearing section having the above configuration.

[The problem that the idea aims to solve]

On the other hand, in the highly important cam bearing described above, it is necessary to suppress leakage of lubricating oil as much as possible. However, when the cam cap mating surface and the head cover mating surface are on the same surface, and the structure is such that two camshafts are mounted in parallel on the top of the cylinder head, the semicircular arc-shaped recess of the cam bearing part can be removed. Of the sandwiched cam cap mating surfaces, the mating surface that is closer to the head cover mating surface parallel to the camshaft is necessarily provided close to the intersection of the front and rear and left and right head cover mating surfaces. That is, the cam cap mating surface is near the four corners of the cylinder head and is continuous with both the head cover mating surface perpendicular to the camshaft and the head cover mating surface parallel to the camshaft.

Even in this case, the lubricating oil seeping from the cam cap mating surface tends to leak out of the head from the part of the head cover mating surface where the gasket surface pressure is low, so to prevent this, the lubricating oil on the cam cap mating surface is It is necessary to improve the sealing performance of the surface, and a liquid sealant is often applied to that surface.

At that time, when the cam cap is fixed, some of the extra liquid sealing material will protrude, but it will also try to advance into the gasket on the mating surface of the head cover, which is the same surface. This is based on the fact that the cam cap mating surface is located near the intersection of the head cover mating surface, and there are fewer edges formed around the cam cap mating surface that tend to flow out than in the case of the above-described structure. For this reason, the liquid sealant also flows toward the gasket, but the surface pressure at the base of the arched portion described above is higher than toward the gasket, which has a high surface pressure and is in complete contact with the head cover mating surface. The amount directed to the gasket with the lower temperature will be greater.

Therefore, the gasket in that area is deformed, the sealing effect is reduced, and the lubricating oil in the cylinder head is encouraged to leak out of the head cover. As a result, the lubricating oil is consumed, and the lubricating oil also adheres to the above-mentioned timing belt, causing problems such as hindering the rotation of the camshaft.

The present invention was developed in view of the above-mentioned problems, and its purpose is to prevent the liquid sealant protruding from the cam cap mating surface from entering the head cover mating surface, to collect it in front of it or to drain it elsewhere. In other words, even if the cap mating surface is located near the intersection of the head cover mating surface, by substantially increasing the edges that are likely to flow out around the cam cap mating surface. Therefore, it is possible to increase the number of locations where leakage can easily occur. This prevents the liquid sealant from advancing to the base of the arched part where the gasket surface pressure is low, ensuring the sealing performance of the gasket, and removing the lubricating oil scraped up on the inner wall surface of the head cover. To provide a cylinder head structure capable of improving the reliability of the cylinder head by preventing lubricating oil from leaking to the outside by returning it to an oil reservoir in a head cover without letting it enter the head cover mating surface.

[Means to solve the problem]

In this invention, two camshafts are mounted in parallel on the top of the cylinder head to open and close the intake and exhaust valves, and the cam cap mating surface of the cam bearing closest to the belt cover of the camshaft is attached to the cylinder head. A head cover mating surface extending in a direction perpendicular to the camshaft and a head cover mating surface extending in a direction parallel to the camshaft are formed continuously at the same height and close to the head cover mating surface extending in a direction perpendicular to the camshaft around the upper part of the head, and the liquid sealing material is applied to the cam cap mating surface. Applies to the cylinder head being coated.

Its characteristic feature is that, at the boundary between the head cover mating surface and the cam cap mating surface, which extend in a direction parallel to the camshaft, a piston extends parallel to the camshaft and inward of the cylinder head;
An open groove communicating with the space inside the cylinder head is formed.

[Effect of idea]

According to the present invention, the cam cap mating surface is continuous with the head cover mating surface extending in a direction perpendicular to the camshaft and the head cover mating surface parallel to the camshaft, and has the same surface shape.
An open groove is formed between the cam cap mating surface and the head cover mating surface extending parallel to the cam cap mating surface, and an edge corresponding to an edge from which the liquid sealing material easily flows out is provided around the cam cap mating surface.
Although the excess liquid sealant applied to the cam cap mating surface enters the head cover mating surface, for the time being it moves in a direction where there is little resistance, that is, the gasket does not come close, so the surface pressure is low. However, the amount of liquid sealing material directed toward the base of the arched portion where the gasket is present is reduced. Therefore, the liquid sealant is prevented from entering the head cover mating surface, and the sealing performance between the head cover and the cylinder head by the gasket is ensured. Furthermore, the lubricating oil that has been scooped up on the inner wall of the head cover can escape into the cylinder head through the open groove, thereby preventing the lubricating oil from leaking outside the head.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples thereof. FIG. 2 is a plan view of a cylinder head 1 to which the cylinder head structure of the present invention is applied, in which four cylinder bores 2 are arranged in a line in the left-right direction of the figure. Two camshafts are attached to each bore for opening and closing an intake valve and an exhaust valve (not shown) provided for each bore, and semicircular arc-shaped cam bearings 3 and 4 are provided for each. It is formed to be recessed from the head cover mating surface 11. A tappet insertion hole 5 into which a tappet that is moved up and down by the cam head of the camshaft is inserted is formed between the respective cam bearings 3 and 4. In an engine in which two camshafts are arranged in this way, the plug boss portion 6 to which the spark plug for each cylinder is attached is arranged approximately at the center of each cylinder bore 2.

The above-mentioned camshaft rotates as the rotation of the crankshaft is transmitted, and one end of the camshaft protrudes toward the belt cover 7 shown by the imaginary line on the side of the head in FIG. etc. can be attached. As a result, the bearing load on the cam bearings 3A and 4A closest to the belt cover 7 increases, and the lubrication at these parts is reduced to the cam bearings 3B and 4A at other parts of the camshaft.
It is more important than B etc. A cam cap 8 shown by the imaginary line in FIG. 3 is placed over both of the cam bearing parts 3 and 4, and the mating surface 9A on which the cam cap 8 is attached in the above-mentioned bearing part 3A
is the same surface as the mating surface 11 of the cylinder head 1 and the belt cover 10, and both mating surfaces 9A,
11 are arranged very close to each other as shown in FIG. That is, the cam bearing portion 3A of the camshaft closest to the belt cover 7
A cam cap mating surface 9A is formed continuously at the same height and close to a head cover mating surface 11A extending in a direction perpendicular to the camshaft around the upper part of the cylinder head 1 and a head cover mating surface 11B extending in a direction parallel to the camshaft. ing. In this way, in an engine equipped with two camshafts, the cam cap mating surface 9A of the cam cap mating surfaces 9 in the cam bearings 3A, 4A is located near one of the four corners of the upper surface of the cylinder head 1. There are many cases where this is unavoidable.

In such a cam bearing portion 3a, a liquid sealing material is applied to the cam cap mating surface 9A in order to suppress leakage of lubricating oil from the bearing surface. At the boundary between the head cover mating surface 11B and the cam cap mating surface 9A, which extend in a direction parallel to the camshaft, there is an opening recess that extends parallel to the camshaft and inward of the cylinder head 1 and communicates with the space inside the cylinder head 1. A groove 12 is formed. As a result, by substantially increasing the number of edges around the cam cap mating surface 9A, it is possible to increase the number of locations where water can easily flow out. This is because the outflow of the liquid sealing material is slow in areas without edges, but in areas where edges are present, there is nothing to act as a dam, and the outflow of the liquid sealing material is accelerated. Therefore, the opening groove 12 is connected to the cam cap mating surface 9A.
It functions to store excess liquid sealing material that has protruded from the head cover so that it does not enter the head cover mating surfaces 11A and 11B.

As shown in FIG. 3, this open groove 12 is located immediately beside the end of the mating surface 9A, but the open groove 12 itself is designed to partially overlap within the plane of the mating surface 9A. [See 12 indicated by the broken line in Figure 3]. In any case, the size of the opening groove 12 is such that it can store the liquid sealing material that protrudes from the mating surface 9A, and is designed to have enough room even when it is stored. . The head cover 10 is placed over the cylinder head 1, and a gasket 13 is interposed on the mating surface 11 thereof. The gasket 13 is located at a position where it intersects with the camshaft.
As shown in Fig. 4, it is arched so as to straddle the upper surface of the camshaft.

At the root portion 13b of the arched portion 13a, the surface pressure that presses the gasket 13 tends to be low, and the lubricating oil from the cam bearing portion 3A described above is
It is more prone to leakage than other areas. However, even though the surface pressure at the base 13b is low, it is difficult for the liquid sealant to enter the area where the gasket 13 is not present, so the liquid sealant follows the directions shown by arrows P and Q in FIG. , the gas flows out while avoiding the part where the gasket 13 is present, as indicated by the broken line arrow R.

Since the above-mentioned open groove 12 is provided close to the direction of the arrow Q where liquid sealant tends to flow out, even if the liquid sealant advances toward the head cover mating surface 11B, it will be collected in the open groove 12 and will not flow out. Further advances will be blocked. When the liquid sealant enters the open groove 12 where it easily flows out, the flow toward the belt cover mating surface 11A is also significantly reduced. Note that 14 and 15 in FIG. 3 are oil holes and passages for guiding the lubricating oil that lubricates the cam bearing 3A to the oil reservoir of the cylinder head 1, and 16 is a passage for fixing the cam cap 8 on the cam cap mating surface 9. It is a bolt hole.

According to the embodiment having such a configuration, the opening groove 1
2 is used to prevent the liquid sealant from spreading,
High sealing performance of the gasket 13 is ensured.

First, a camshaft (not shown) is fitted into each cam bearing portion 3 of the cylinder head 1, a cam cap 8 is placed on the camshaft, and then the camshaft is fixed to the cylinder head 1 using bolts. At this time, a liquid sealant is applied to the cam cap mating surface 9A of the cam bearing portion 3A, and similarly applied to other cam bearing portions 3B and the like as required. When the cam cap 8 is fixed to the cylinder head 1, for example, an excess amount of the liquid sealing material protrudes from the cam cap mating surface 9A of the cam bearing portion 3A.

In the case of an engine equipped with two camshafts, focusing on one cam cap mating surface 9A, there are relatively few discontinuous areas with edges around the mating surface 9A, and belt cover mating The area continuous with surfaces 11A and 11B becomes wider. However, due to the presence of the open groove 12, the number of locations where the liquid sealing material is likely to flow out is greater than in the case where the open groove 12 is not provided. Generally, the liquid sealant applied to the cam cap mating surface 9A tends to spread around the entire circumference, but in this case,
It mainly tries to flow out in the directions shown by arrows P and Q in FIG. Of course, dashed arrow R
This is because gasket 13 is present there even though the surface pressure is low, so the gas will try to flow out in the direction of less resistance where gasket 13 does not exist.

Therefore, the liquid sealing material flows through the open groove 12 provided immediately beside the cam cap mating surface 9A.
The head cover mating surface 11A, which flows into the head cover mating surface 9A and is flush with the cam cap mating surface 9A,
Advancement to 11B is prevented. If the liquid sealant advances into the gasket 13 of the belt cover mating surface 11A and deforms it, the sealing performance of the gasket 13 at that location will be significantly impaired, but such a situation can be avoided. Ru. Of course, as mentioned above, the surface pressure tends to be high at the arched base 13b of the gasket 13 at the location where the camshaft protrudes outside the head, and it is difficult to ensure this. Since the sealing material is prevented from advancing, there is no further deterioration in sealing performance. Therefore, if the lubricating oil is wasted unnecessarily, nothing will happen.

By the way, inside the head cover 10, the cylinder head 1 is connected by the cam head of the camshaft.
The lubricating oil inside is scraped up to lubricate the camshaft, etc. At that time, the scraped up lubricating oil adheres to the inner wall of the head cover 10,
This is transmitted to the wall and the head cover mating surface 11A,
It hangs down to 11B. The viscosity of the lubricating oil decreases due to the heat of the engine, making it easy to enter the small gap in the gasket. However, in the arched base portion 13b described above, the lubricating oil is transmitted through the open groove 12. The cylinder head 1 is then guided toward the inside of the cylinder head 1. Therefore, the base 13
Oil leakage from b is suppressed.

A mechanism for transmitting rotation from the crankshaft to the camshaft is installed outside the arched portion 13a, and a belt cover 7 is provided to prevent condensation and dust from entering the mechanism. If the above-mentioned lubricating oil enters into the belt cover 7, the life of the timing belt will be significantly shortened, but as mentioned above, leakage of the lubricating oil is also prevented by the presence of the open groove 12. This also avoids harmful effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of an embodiment of the cylinder head structure of the present invention, and an enlarged view of section M in FIG.
FIG. 2 is an overall plan view of a cylinder head to which the present invention is applied, FIG. 3 is a sectional view taken along the line -- in FIG. 1, and FIG. 4 is a perspective view showing the arched portion of the gasket. 1... Cylinder head, 3A, 4A... Cam bearing portion, 7... Belt cover, 9A... Cam cap mating surface, 11... Head cover mating surface, 11A... Head cover mating surface extending in a direction perpendicular to the camshaft, 11B... Direction parallel to the camshaft. Head cover mating surface extending to 12...opening groove.

Claims (1)

[Scope of claim for utility model registration] Two camshafts are installed in parallel at the top of the cylinder head to open and close intake and exhaust valves, and the cam caps of the cam bearings on the side closest to the belt cover of the camshafts are aligned. A surface is formed continuously at the same height and close to a head cover mating surface extending in a direction perpendicular to the camshaft and a head cover mating surface extending in a direction parallel to the camshaft around the upper part of the cylinder head, and a surface is formed continuously on the cam cap mating surface. In the cylinder head to which the liquid sealing material is applied, a seal is applied to the boundary between the head cover mating surface and the cam cap mating surface, which extend in a direction parallel to the camshaft, and which extends parallel to the camshaft and inward of the cylinder head. A cylinder head structure characterized in that an open groove communicating with an inner space is formed.