JP2000045864A - Sealing structure for compression chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dead volume as in a conventional case and eliminate compression leakage irrespective of a load state. SOLUTION: A compression chamber is determined by a lower surface of a cylinder head 2, an inner portion of a cylinder 3, and a head of a piston reciprocating inside the cylinder 3. An opening is formed correspondingly to the compression chamber so as to prevent leakage from the compression chamber. A head gasket is sandwiched between the lower surface of the cylinder head 2 and the upper surface of the cylinder 3 so as to locate the compression chamber in the opening. In such a sealing structure, the head gasket has one- plate form 1A. It has a widened opening 1g on whose substantially widening corresponding position a ring 1B is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression chamber sealing structure suitable for an internal combustion engine or the like.

[0002]

2. Description of the Related Art An internal combustion engine, a compressor or the like having a cylinder head, a cylinder, and a piston reciprocating in the cylinder includes a combustion chamber surrounded by a lower surface of the cylinder head, an inside of the cylinder, and a head of the piston. It has a chamber and a compression chamber (hereinafter referred to as “compression chamber”). When the piston reciprocates, an explosion pressure or a compression pressure (hereinafter referred to as “compression pressure”) is generated in the compression chamber. At this time, a portion other than the so-called exhaust valve or intake valve (ie, the lower surface of the cylinder head and the cylinder). The head gasket is clamped by a head bolt or the like at this joint so that no compression leakage occurs from the joint with the upper surface of the gasket. The head gasket has an opening corresponding to the compression chamber, and is assembled so that the compression chamber is located in the opening.

[0003] The cylinder includes a cylinder block itself in which a piston insertion hole is directly formed in a cylinder block, and a cylinder liner fitted in a hole provided in the cylinder block. The present invention, which will be described in detail later, does not distinguish between them.

There are two types of head gaskets: one in which asbestos is sandwiched between upper and lower thin plates, and the other is a single plate. In the present invention, which will be described in detail later, the latter single plate is targeted.

[0005]

However, the conventional single-plate head gasket has the following disadvantages.

For example, FIG. 9A is a plan view of an example of a single-plate head gasket 1 installed for each compression chamber of an internal combustion engine. The head gasket 1 has one opening 1a corresponding to the combustion chamber, six head bolt holes 1b,
One auxiliary head bolt hole 1c, four water holes 1d,
One lubricating oil hole 1e and one push rod hole 1f
And two knock pin holes (not shown) for positioning with respect to the cylinder 3 and the cylinder head 2. As shown in the assembly drawing of FIG. 9B, the combustion chamber is arranged at the joint between the lower surface of the cylinder head 2 and the upper surface of the cylinder 3 and in the opening 1a, and the six heads are arranged. It is pinched by bolts (not shown). Here, in the head gasket 1, the tightening order and tightening torque of the six head bolts are controlled so that the surface pressures on the lower surface of the cylinder head 2 and the upper surface of the cylinder 3 are substantially uniform. However, the single-plate head gasket has the following first and second characteristics regardless of the example of the head gasket 1.

(1) Irrespective of the tightening order and tightening torque of the head bolts, the surface pressure due to the tightening torque decreases as the distance from the head bolt or the like increases. However, the position of each head bolt hole 1b cannot be arranged near the opening 1a as illustrated in FIG. 9A. Therefore, the surface pressure decreases as the position is closer to the opening 1a. In addition, if the head bolt interval cannot be made uniform due to the structure, there is a first characteristic that the surface pressure is reduced at a large bolt interval.

(2) On the other hand, the opening 1 of the head gasket 1
It is desirable to work so that a and the compression chamber match as much as possible. This is because when the opening 1a and the compression chamber are largely separated from each other, the so-called dead volume 4 increases. Since the dead volume 4 is a fixed space in the compression chamber, the larger the dead volume, the lower the compression efficiency based on the reciprocating motion of the piston. For example, in an internal combustion engine, if the dead volume 4 is large, poor combustion occurs. That is, in order to eliminate the dead volume 4, as described above, there is the second characteristic that it is desirable to process the opening la of the head gasket 1 and the compression chamber as much as possible.

However, the first and second characteristics are reciprocal events. The smaller the dead volume 4, the higher the compression efficiency. However, the smaller the dead volume 4, the more the end face of the opening 1a of the head gasket 1 becomes farther from the head bolt or the like. The pressure drops. Specifically, in the internal combustion engine, carbon C is deposited on the upper surface of the inner peripheral end forming the opening 1a due to the decrease in the surface pressure as shown in the assembly diagram of FIG. .

Therefore, as shown in the assembly drawing of FIG. 9D, the opening 1a of the head gasket 1 is formed on the upper surface of the cylinder 3.
And a cylinder 3 having an annular projection 3a (hereinafter, referred to as a "first projection 3a") at a position surrounding the lower surface of the head gasket 1.

Thus, even if the length L1 from the first projection 3a to the opening 1a is long, the inner peripheral end of the opening 1a formed by the tightening of the head bolt is viewed from the first projection 3a as a fulcrum. As shown in (1), the upper surface of the inner peripheral end forming the opening 1a is pressed against the lower surface of the cylinder head 2, and the surface pressure increases accordingly. As a result, the dead volume 4 can be reduced, and carbon C can be avoided from accumulating due to the increase in the surface pressure (and compression leakage can be avoided).

However, for example, in an internal combustion engine of a construction machine which is always subjected to a high load, although the above result can be suitably obtained, after the vehicle is once driven (for example, a high load is once applied), for example, a diesel locomotive running on a rail. In an internal combustion engine that maintains low-load operation (after that time), carbon C is still deposited and a compression leak occurs. Rather, carbon C actually accumulates in a large amount, and therefore, there is a tendency that compression leakage is also large. The reasons are as follows.

That is, the head gasket 1, the cylinder head 2, the cylinder 3, the cylinder bolts and the like thermally expand at the time of a high load immediately after the start of the vehicle. Thereafter, when the vehicle speed reaches a certain vehicle speed and shifts to coasting operation with a low load, the cylinder head 2 is directly cooled by the traveling wind and contracts, but the head bolt is not directly cooled, so that the state where the thermal expansion is maintained is maintained for a long time. . Accordingly, during this time, the tightening torque of the head bolt is reduced, and the surface pressure is significantly reduced due to the long length L1, and carbon C is rather easily deposited. That is, the compression leakage tends to be large.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to provide a closed structure of a compression chamber in which a dead volume can be reduced as in the related art and compression leakage can be eliminated regardless of a load state.

[0015]

In order to achieve the above object, a first closed structure of a compression chamber according to the present invention is described with reference to, for example, FIG.
, A compression chamber surrounded by the inside of the cylinder 3 and the head of a piston that reciprocates inside the cylinder 3,
In order to prevent compression leakage from the compression chamber, an opening 1a corresponding to the compression chamber is provided, and between the lower surface of the cylinder head 2 and the upper surface of the cylinder 3 so that the compression chamber is located in the opening 1a. In the closed structure of the compression chamber in which the head gasket 1 is sandwiched, the head gasket 1 is a single plate 1A, has an enlarged opening 1g, and has a ring 1B at a position substantially equivalent to the enlarged opening 1g. It is characterized by.

According to the first configuration, the following operation and effect can be obtained. The inner peripheral end surface of the enlarged opening 1g is the conventional opening 1a.
Is closer to the head bolt hole 1b by an amount that is larger than the inner peripheral end face. As a result, the average surface pressure of the head gasket 1A with respect to the cylinder head 2 and the cylinder 3 based on the tightening torque of the head bolt becomes high and uniform.
Therefore, carbon C is unlikely to be deposited between the upper surface of the inner peripheral end forming the enlarged opening 1g and the lower surface of the cylinder head 2. When the compression chamber is a combustion chamber, the thermal deformation of the head gasket 1A is reduced by the reduced gasket area. Therefore, regardless of the load, carbon C from the combustion chamber
(That is, compression leakage and explosion leakage can be prevented). Moreover, the dead volume 4 can be made the same volume as the conventional one by the ring 1B. As a result,
The compression efficiency does not decrease. Rather, it also becomes an obstacle to prevent carbon C from being deposited on the head gasket 1A. Further, since the ring 1B prevents heat propagation to the head gasket 1A, thermal deformation of the head gasket 1A can be reduced. Further, since the ring 1B is a small product, it is easy to perform a delicate processing to further reduce the dead volume 4. Of course, there is a degree of freedom in which the size and arrangement position of the ring 1B can be freely changed. For example, head gasket 1A
Ring 1 with a gap δ from the inner peripheral end face of enlarged opening 1g of
B may be arranged. In this way, it is easy to process,
Yield also improves. Also, it is possible to suitably cope with the thermal expansion of the ring 1B itself. Also, the ring 1B can be configured to be slightly thinner than the head gasket 1A. In short, various kinds of rings 1B can be prepared so as not to impair the above-mentioned effects.

Second, in the closed structure of the compression chamber of the first configuration, for example, referring to FIG.
A first projection 3a is provided on the upper surface of the head gasket 1A so as to surround the enlarged opening 1g of the head gasket 1A and abut on the lower surface of the head gasket 1A.

According to the second configuration, the following operation and effect can be obtained. When the head gasket 1A is placed on the first protrusion 3a and clamped by a head bolt, the head gasket 1A
The inner peripheral end forming the enlarged opening 1g of A is bent upward with the first projection 3a as a fulcrum, and the upper surface of the inner peripheral end forming the enlarged opening 1g strongly presses the lower surface of the cylinder head 2. Accordingly, the surface pressure is further increased accordingly. Moreover, 1g of enlarged opening
Is larger than the conventional opening Ia, the head bolt hole 1
b. As a result, the operation and effect of the first configuration can be obtained more reliably.

Third, in the closed structure of the compression chamber having the second configuration, for example, referring to FIG. 6, a recess 1c1 is provided on the side surface of the cylinder of the head gasket 1C so as to surround the first projection 3a. On the other hand, a protrusion 1c2 is provided at a position corresponding to the recess 1c1 on the side surface of the cylinder head and at a position in contact with the lower surface of the cylinder head.

According to the third configuration, the following operation and effect can be obtained. When the head bolt is tightened, the inner peripheral end forming the enlarged opening 1g is bent toward the cylinder head 2 with the projection 1c2 as the first fulcrum and the first projection 3a as the second fulcrum. The function and effect can be obtained more reliably. In addition, the concave portion 1c1 is a press mark for forming the convex portion 1c2, and makes it easy to bend the inner peripheral end portion forming the enlarged opening 1g.

Fourth, in the closed structure of the compression chamber having the second configuration, for example, with reference to FIG. 7, the lower surface of the cylinder head 2 is formed on the lower surface of the cylinder head 2 so as to surround the first projection 3a and to form the head gasket 1A. The second protrusion 2a is located at a position where it contacts the upper surface.
It is characterized by having.

According to the fourth configuration, the following operation and effect can be obtained. The second projection 2a replaces the projection 1c2 of the head gasket 1C in the third configuration. Therefore, according to the fourth configuration, the same operation and effect as those of the third configuration can be obtained.

[0023]

Embodiments and Examples of the Invention Hereinafter, examples will be described with reference to FIGS.
This will be described with reference to FIG. 1 is a first embodiment, and FIG. 2 is a second embodiment.
Example, FIGS. 3 to 5 show the test results of the first and second examples, etc., FIG. 6 shows the third example, FIG. 7 shows the fourth example, and FIG. 8 shows the fifth example.

The first embodiment shown in FIGS. 1 to 5 is as follows.
The head gasket 1A is for an internal combustion engine, like the conventional head gasket 1 of FIG. 9A, and is a single plate. And as shown in FIG. 1A, it has one enlarged opening 1g corresponding to the combustion chamber. Also, at the same position as the conventional head gasket 1, six head bolt holes 1b,
One auxiliary head bolt hole 1c, four water holes 1d,
One lubricating oil hole 1e and one push rod hole 1f
And two knock pin holes (not shown) for positioning with respect to the cylinder 3 and the cylinder head 2. As shown in FIG. 1A, the head gasket 1A has a ring 1B shown in FIG. 1B that can be freely fitted inside the enlarged opening 1g. That is, the ring 1B is sized so that the enlarged opening 1g is disposed at that position by an amount substantially enlarged as compared with the conventional opening 1a.
As shown in (c), the size is such that a dead volume 4 having substantially the same volume as the conventional one is secured.

More specifically, as shown in FIG.
The head gasket 1A has a ring 1B inside the enlarged opening 1g.
Are arranged at the joint between the lower surface of the cylinder head 2 and the upper surface of the cylinder 3 so that the combustion chamber is located in the ring 1B, and are sandwiched by six head bolts (not shown).

According to the first embodiment, the following operation and effect can be obtained. The inner peripheral end face of the enlarged opening 1g is the conventional opening 1
The portion closer to the head bolt hole 1b is larger than the inner peripheral end surface of the portion a. For this reason, the average surface pressure of the head gasket 1A against the cylinder head 2 and the cylinder 3 based on the tightening torque of the head bolt is increased and becomes uniform. Therefore, carbon C is unlikely to be deposited between the upper surface of the inner peripheral end forming the enlarged opening 1g and the lower surface of the cylinder head 2.
In addition, the head gasket 1
熱 also reduces thermal deformation. Therefore, regardless of the load, deposition of carbon C can be prevented (that is, compression leakage can be prevented). Moreover, the dead volume 4 has the same volume as the conventional one due to the ring 1B. As a result, the compression efficiency does not decrease. Rather, it also becomes an obstacle to prevent carbon C from being deposited on the head gasket 1A. Further, the ring 1B prevents heat propagation to the head gasket 1A.
Therefore, thermal deformation of the head gasket 1A can be reduced. Further, since the ring 1B is a small product, it is easy to perform a delicate processing to further reduce the dead volume 4. Of course, there is a degree of freedom in which the size and arrangement position of the ring 1B can be freely changed. For example, the ring 1B may be arranged with a gap δ from the inner peripheral end face of the enlarged opening 1g of the head gasket 1 #, as exemplified in FIG. This facilitates processing and improves the yield. Further, it is possible to suitably cope with the thermal expansion of the ring 1B itself. Also, make the ring 1 slightly thinner than the head gasket 1A.
B can be freely configured. In short, various types of rings 1B can be prepared so as not to impair the above-mentioned effects.

The second embodiment shown in FIG. 2 is as follows. In the second embodiment, as shown in FIG. 2 (a), the second projection 2a is formed on the upper surface of the cylinder 3 so as to surround the enlarged opening 1g of the head gasket 1A and abut on the lower surface of the head gasket 1 #. (Note that the first projection 3
a itself is a well-known prior art as described above). Others are the same as the first embodiment.

According to the second embodiment, the following operation and effect can be obtained. When the head gasket 1A is placed on the first projection 3a and clamped by the head bolt, as shown in FIG. 2 (b), the inner peripheral end forming the enlarged opening 1g of the head gasket 1A becomes the first projection 3a. As shown in arrow X, the upper surface of the inner peripheral end forming the enlarged opening 1 g strongly presses the lower surface of the cylinder head 2. Accordingly, the surface pressure is further increased accordingly. In addition, the enlarged opening 1g is closer to the head bolt hole 1b by an amount larger than the conventional opening 1a (from L1 to L2 (L1> L2)). As a result, the operation and effect of the first embodiment can be more reliably obtained.

The operation and effect of the first and second embodiments will be described with reference to FIGS. 3 to 5 based on test data in comparison with the prior art.

As shown in FIG. 3, a conventional opening 1 is provided between a cylinder head 2 and a cylinder 3 having a first projection 3a.
a, a head gasket 1Ca having a concave portion 1c1 on the lower surface of the conventional head gasket 1 having the opening 1a and a convex portion 1c2 at an upper surface position corresponding to the concave portion 1c1, Enlarged aperture 1 in the embodiment
When the head gasket 1A having g was replaced and the head gasket 1A was tightened with a head bolt, the surface pressure distribution at each position was obtained as shown in FIG. In FIG. 4, a dashed line S
Reference numeral 1 denotes a surface pressure distribution based on the head gasket 1. A dotted line S2 is a surface pressure distribution based on the head gasket 1Ca. The solid line S3 is the surface pressure distribution based on the head gasket 1A. As is apparent from FIG.
1 and the contact pressure in the vicinity of the opening 1a at the dotted line S2 is the solid line S3
The value is much smaller than the surface pressure near the enlarged opening 1g in the above. Therefore, as shown in FIG. 5, in the head gasket 1, as shown in FIG. 5A, carbon C is deposited from the opening 1a to the first protrusion 3a without any difficulty. In the head gasket 1Ca, as shown in FIG. 5 (b), carbon C is deposited almost to the center from the opening 1a to the first protrusion 3a (note that FIG. 5 (b) shows the upper surface of the head gasket lCa by the convex portion 1c2). Although it is described that a gap is formed between the cylinder and the lower surface of the cylinder head 2, this is only the protrusion 1 c2 and the gap as shown is not formed.) In the head gasket 1A, FIG.
As shown in (b), no carbon C is deposited. From the surroundings, the effect of the head gasket 1A in the first and second embodiments can be grasped. In addition, head gasket 1Ca
Is also more effective than the head gasket 1. Therefore, the following third to fifth embodiments can be constructed.

That is, in the third embodiment, as shown in FIG. 6, the head gasket 1C is different from the head gasket 1A having the enlarged opening 1g of the first embodiment in that the first projection 3a on the cylinder 3 is provided on the side surface of the cylinder 3. It has a concave portion 1c1 to surround it and a convex portion 1c2 at a position corresponding to the concave portion 1cl on the side surface of the cylinder head 2 and at a position in contact with the lower surface of the cylinder head 2. Other points such as the arrangement of the ring 1B are the same as those of the first embodiment.

According to the third embodiment, the following operation and effect can be obtained. When the head bolt is tightened, the projection 1c2 is used as a first fulcrum, and the first projection 3a is used as a second fulcrum. The function and effect of (1) can be obtained more reliably. The first protrusions 3a and the protrusions 1c2 are not as large as shown in the figure. Therefore, by increasing the number of fulcrums, carbon deposition and compression leakage can be more reliably prevented. In addition, the concave portion 1c1 is a press mark for forming the convex portion 1c2, and also makes it easy to bend the inner peripheral end portion forming the enlarged opening 1g.

In the fourth embodiment, as shown in FIG. 7, the cylinder head 2 has a head gasket 1A on its lower surface surrounding the first projection 3a of the cylinder 3 and having the enlarged opening 1g of the first embodiment. The second protrusion 2a is located at a position where it contacts the upper surface.
Having. Other points such as arranging the ring 1B are the first.
This is the same as the embodiment.

According to the fourth embodiment, the following operation and effect can be obtained. The second projection 2a replaces the projection 1c2 of the head gasket 1C in the third embodiment. Therefore, according to the fourth embodiment, the same operation and effect as those of the third embodiment can be obtained.

As shown in FIG. 8, the fifth embodiment uses the head gasket 1C of the third embodiment. However, the first projection 3a is omitted from the cylinder 3. Other ring 1
The arrangement of B is the same as in the first embodiment.

According to the fifth embodiment, the following operation and effect can be obtained. When the head bolt is tightened, the inner peripheral end forming the enlarged opening 1g is bent toward the cylinder head 2 with the projection 1c2 as a first fulcrum. For this reason, it is possible to obtain substantially the same operation and effect as the operation and effect of the second embodiment. According to the fifth embodiment, the enlarged opening 1g can be further enlarged by the amount that the cylinder 3 does not have the first protrusion 3a. As a result, the deposition of carbon C can be further reduced.

The head gasket 1 in the above embodiment
Each of A and 1C is a single plate, but the meaning of this single plate includes one in which different materials are overlapped (the same applies in the claims). Various materials such as iron, steel (for example, cold-rolled steel plate SPCCT), copper, aluminum, and aluminum alloy can be prepared.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment, wherein FIG. 1A is a plan view of a head gasket, FIG. 1B is a plan view of a ring, and FIG.

FIGS. 2A and 2B show a second embodiment, in which FIG. 2A is an assembly view, and FIG.

FIG. 3 is an assembly view of the first and second embodiments and the like.

FIG. 4 is a surface pressure distribution draf based on FIG. 3;

FIGS. 5A and 5B are carbon deposition diagrams based on FIG. 3, wherein FIG. 5A is a diagram of the prior art, FIG. 5B is a partially modified diagram of the prior art, and FIG.
FIG. 4 is a diagram of the first and second embodiments.

FIG. 6 is an assembly view of the third embodiment.

FIG. 7 is an assembly view of the fourth embodiment.

FIG. 8 is an assembly view of the fifth embodiment.

9 (a) is a plan view of the head gasket, FIG. 9 (b) is an assembly drawing, FIG. 9 (c) is a carbon deposition diagram, and FIG. 9 (d) is assembly of the head gasket to the cylinder having the first projection. FIG.

[Explanation of symbols]

 1, 1A, 1C Head gasket 1a Opening 1c1 Recess 1c2 Convex 1g Enlarged opening 1B Ring 2 Cylinder head 3 Cylinder 3a First protrusion 2a Second protrusion

Claims (4)

[Claims] A lower surface of a cylinder head (2) and a cylinder
(3) and a compression chamber surrounded by the head of a piston reciprocating in the cylinder (3), and an opening corresponding to the compression chamber to prevent compression leakage from the compression chamber. (1a), a head gasket (1) is sandwiched between the lower surface of the cylinder head (2) and the upper surface of the cylinder (3) so that the compression chamber is located in the opening (1a). In the closed structure of the compression chamber, the head gasket (1) is a single plate (1A) 1 and has an enlarged opening (1g), and a ring (1B) is provided at a position substantially equivalent to the enlarged opening (1g). A closed structure for a compression chamber, characterized by having: 2. A head gasket is provided on the upper surface of the cylinder (3).
The hermetically sealed structure of a compression chamber according to claim 1, wherein the first projection (3a) is provided at a position surrounding the enlarged opening (1g) of the (1A) and abutting against a lower surface of the head gasket (1A). . 3. A head gasket (1A) has a recess (1c1) on the side of the cylinder surrounding the first projection (3a), and at a position corresponding to the recess (1c1) on the side of the cylinder head, The hermetically sealed structure of a compression chamber according to claim 2, further comprising a projection (1c2) at a position in contact with the lower surface of the cylinder head. 4. A first projection is provided on a lower surface of the cylinder head (2).
The sealing structure for a compression chamber according to claim 2, wherein the second projection (2a) is provided at a position surrounding the (3a) and in contact with the upper surface of the head gasket (1A).