JPH0346208Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a seal structure for an engine, and more particularly, to an engine in which a gas vent groove is formed at the joint between a cylinder block and a cylinder head. This is used in the field of preventing combustion gas from leaking outside from the joint.

[Conventional technology]

A gasket made of fiber or the like is inserted between the cylinder block and cylinder head of the engine to prevent combustion gas from leaking from the combustion chamber.

However, if the gasket burns out due to the heat generated by combustion, the head bolts that connect the cylinder block and cylinder head become loose. As a result, the function of the gasket deteriorates, the sealing performance at the joint is impaired, and combustion gas leaks to the outside air.

[The problem that the idea attempts to solve]

In order to prevent the combustion gas that has entered the above-mentioned joint portion from leaking outside, it is desirable to be able to return the combustion gas into the engine.
For example, Japanese Utility Model Publication No. 52-34490 discloses a combustion gas seal in which a gap is formed on the outer periphery of the bore in the mating part, and this gap is communicated with the intake hole of the engine via a small hole extending in the vertical direction. The equipment is described.

According to this, the combustion gas that has entered the joint portion is led out to the small hole through the space gap, and the combustion gas that has reached the intake hole is burned again in the combustion chamber. Therefore, combustion gas is prevented from directly leaking out of the engine from the joint, and air pollution is prevented. However, if the intake negative pressure is large, leakage of combustion gas from the joint to the intake hole will be promoted.

On the other hand, it is conceivable to lead the combustion gas to the exhaust hole through the above-mentioned small hole, but if the back pressure of the engine becomes high, the exhaust gas may be blown back from the exhaust hole into the space gap. Same as above, it is not preferable.

By the way, if the gasket interposed in the mating portion is made of the above-mentioned fibrous material, it will be easily damaged by combustion gas, and its durability will be poor. Recently, highly durable metal gaskets have been used instead of gaskets with such qualities.

However, in the case of metal plates, it is undeniable that the gasket deteriorates the sealing performance of the mating part that is originally required, and the above-mentioned space gap formed on the outer circumferential side of the bore in the mating part and the gas (not shown) It will become even more essential to recover combustion gas from vents and the like.

The present invention was developed in view of the above-mentioned problems.The purpose of this invention is to prevent the combustion gas that enters the joint due to the reduced sealing performance caused by the use of a metal gasket from leaking directly into the outside air, and to prevent the combustion gas from leaking directly into the engine. To provide a seal structure for an engine that can be recovered without causing any adverse effects on engine operation due to the recovery, and that can be disposed of using an existing structure along with blow-by gas, etc. .

[Means to solve the problem]

In the present invention, a metal gasket is interposed at the joint between the cylinder block and the cylinder head to seal the gap between the cylinder block and the cylinder head, and a gas vent groove is formed on the outer circumferential side of the bore at the joint. Applied to engine seal structure.

The gas vent groove 4 is connected to the upper space in the crankcase 9 or above the oil level in the oil reservoir 17 in the head cover 14 through a communication hole 8 extending in the height direction of the engine through which lubricating oil does not flow. It is communicated with at least one of the spaces.

[Effects of the invention] According to the invention, a metal gasket is interposed in the mating part, and the gas vent groove on the outer circumferential side of the bore is connected to the inside of the crankcase or Since it communicates with the inside of the head cover, the combustion gas that has entered the mating portion can be led out from the gas vent groove to the crankcase or the like through the communication hole.

As a result, combustion gas does not directly leak out of the engine from the mating portion, and pollution of the atmosphere due to the reduction in sealing performance due to the use of the metal gasket is avoided. Moreover, during recovery, there is no problem with engine operation, such as combustion gas returning to the intake passage or exhaust gas being blown back from the exhaust passage into the gas vent groove. Furthermore, this kind of combustion gas recovery operation can be performed with the blow-by gas processing device originally installed in the engine, so there is no need for any special equipment for processing combustion gas. .

〔Example〕

Hereinafter, the present invention will be described in detail based on examples thereof.

FIG. 2 is a plan view of the mating surface 2 of the cylinder block 1 to which the present invention is applied at the mating part between the cylinder block 1 and a cylinder head (not shown). The gasket is placed and the cylinder head is stacked.

In the mating surface 2 of the cylinder block 1, shallow annular gas vent grooves 4, 4 are formed on the outer periphery of each bore 3, 3. The combustion gas that has entered the joint part 2 from the bores 3, 3 side is led out from the gas vent grooves 4, 4 toward a predetermined location, and passes over the gas vent grooves 4, 4 and leaves the joint part 2 from the engine. It is designed to prevent leakage to the outside.

In this example, a gas vent groove 4 is provided concentrically with each bore 3 and communicates with gas vent grooves 4 around other bores 3. These gas vent grooves 4 are
Water jacket 5 in cylinder block 1
(see Fig. 1) and the water jacket in the cylinder head, and bolt holes 7 for head bolts that integrate the cylinder block 1 and the cylinder head, so as not to overlap with each other. Moreover, it is provided as close to the bore 3 as possible.

As shown in FIG. 1, this gas vent groove 4 communicates with the upper space of the crank chamber 10 in the crankcase 9 through a communication hole 8 extending in the height direction of the cylinder block 1 through which lubricating oil does not flow. has been done. The communication hole 8 includes a vertical groove 8A formed along the bolt hole 7a and a vertical hole 8 connected to the vertical groove 8A.
The lower end of the vertical groove 8A extends to a position slightly below the tip of the head bolt (not shown), and the vertical hole 8B is provided directly below the bolt hole 7a.
is connected to.

A lateral groove 11 for guiding the combustion gas that has reached the gas vent groove 4 is communicated with such a communication hole 8, and the horizontal groove 11 is connected to the mating surface 2 of the block 1 at a depth similar to that of the gas vent groove 4 described above. It is formed. In addition,
In FIG. 2, the gas vent grooves 4 provided for each bore 3 are in communication with each other, so the horizontal groove 11 is provided only toward the bolt hole 7a located approximately in the center, and the communication hole 8 is also connected to that bolt hole. It is formed only in 7a.

According to such an embodiment, the combustion gas that has entered the joint portion 2 can be disposed of without leaking into the outside air as described below.

In the combustion chamber formed within the bore 3, high pressure combustion gas is generated during the expansion stroke. A portion of the combustion gas enters the joint 2 between the cylinder block 1 and the cylinder head. When the combustion gas reaches the gas vent groove 4, it flows through the groove 4 and moves from the lateral groove 11 located at the center of the cylinder block 1 to the communication hole 8.

First, it passes through the vertical groove 8A formed along the bolt hole 7a from the horizontal groove 11, and flows down the vertical hole 8B from the lowest part of the bolt hole 7a. This communication hole 8 opens into a crank chamber 10 below the cylinder block 1, and combustion gas is introduced from the upper space in the crankcase 9 onto the oil reservoir and mixed with the blow-by gas floating there.

Incidentally, the lubricating oil in the crankcase 9 is supplied to the cam mechanisms of the intake valve and exhaust valve provided in the cylinder head by an oil pump or the like. Oil return passage 12 for returning the lubricating oil to the crankcase 9
(See FIG. 2) are formed in the cylinder block 1 and the cylinder head, and the above-mentioned combustion gas rises through the return passage 12 together with the blow-by gas and is guided into the head cover (not shown).

Blow-by gas is a mixture of lubricating oil vapor and gas, and combustion gas is a mixture of water vapor and gas. However, an oil separator is attached to the head cover, and the gas separated there is sent to the intake air of an air cleaner, etc. led out into the passage. After the oil is dripped into the cylinder head, it is returned to the crank chamber 10 from the oil return passage 12.

In this way, the combustion gas that has entered the joint part 2 is treated using the blow-by gas treatment device installed in the engine, and the combustion gas leaks directly out of the engine from the joint part 2, polluting the atmosphere. Then, what happened will be avoided. Therefore, when recovering the combustion gas, the combustion gas is not returned to the intake passage, nor is the exhaust gas blown back from the exhaust passage to the gas vent groove, and the operation of the engine is not inhibited.

FIG. 3 shows an example in which the gas vent groove 4 formed in the cylinder block 1 is provided so as to connect each bolt hole 7 linearly. In this way, if the gas venting groove 4 is formed on the outer peripheral side of the bore 3 in the mating surface 2, the combustion gas that has entered the mating portion 2 will be recovered from there and will leak out beyond the gas venting groove 4. is prevented.

Note that the gas vent grooves are not limited to the mating surfaces of the blocks, but can also be found on the mating surfaces of the cylinder heads (not shown).
Alternatively, the metal gasket may be formed on one or both sides of the metal gasket itself interposed between the mating surfaces. In short, it is sufficient that it is formed on the outer circumferential side of the bore in the mating portion so that combustion gas can be recovered.

FIG. 4 shows a different embodiment of the communication hole 8, in which combustion gas that has entered the mating portion 2 is led out into the head cover. Gas vent grooves 4A and 4B are formed on both surfaces of the cylinder block 1 and the cylinder head 14, sandwiching a metal gasket 13 interposed in the mating portion 2.

This gas vent groove 4 communicates directly with a bolt hole 7 formed for a head bolt 15, as shown in FIG. The bolt hole 7 has a diameter larger than that required for the head bolt 15, so that even when the cylinder block 1 and the cylinder head 14 are connected, combustion gas can rise along the periphery of the head bolt 15. ing.

Incidentally, surplus lubricating oil in the cylinder head 14 is returned to the crankcase 9 through the oil return passage 12 (see Fig. 3).
In order to prevent the discharge hole 16 of the communication hole 8 from being blocked by the lubricating oil remaining in the oil sump 1
It is opened above the oil level of No.7.

According to such an example, the combustion gas that has entered the mating portion 2 is transferred from the gas vent groove 4 to the head bolt 15.
The liquid is led out into the space inside the head cover as indicated by an arrow 18 through a communication hole 8 and a discharge hole 16 formed around the head cover. Thereafter, it is processed together with the blow-by gas as in the previous embodiment, and the gas component is led to the intake passage.

FIGS. 5a and 5b show an example in which the metal gasket 13a interposed in the mating portion 2 is ring-shaped and fitted around the outer periphery of the bore 3. FIG. Even when such a gasket is adopted, for example, the gas vent groove 4 is configured by a tapered groove 20 or a stepped groove 21 on the outer periphery connected to the seal ring groove 19 formed on the mating surface 2 of the cylinder block 1, If they are connected to the communication hole 8 described above, they can function in the same way.

As can be seen from the above explanation, the combustion gas that has entered the joint is transferred from the gas vent groove through the communication hole to at least the upper space in the crankcase or the space above the oil level in the oil reservoir in the head cover. It can be derived on the one hand. This prevents combustion gas from directly leaking out of the engine from the mating portion, and prevents air pollution due to a reduction in sealing performance due to the use of a metal gasket. Moreover, it does not cause any adverse effects on the operation of the engine, and can be processed using the blow-by gas processing device originally installed in the engine, so no special processing device is required.

That is, in the present invention, the gas vent groove is communicated with the inside of the crankcase or cylinder head where pressure changes are small. In addition, when connecting the grooves, the openings are placed at positions that are designed to prevent lubricating oil from flowing into the gas vent grooves, so as not to affect the release of combustion gas.

[Brief explanation of drawings]

Fig. 1 shows the main parts of an embodiment of the present invention; Fig. 2 is a sectional view taken along the - line in Fig. 2; Fig. 2 is a plan view showing the mating surfaces of the cylinder blocks; Fig. 3 is a gas vent groove of a different shape. FIG. 4 is a plan view showing the mating surfaces of the cylinder block which has been subjected to the above-described process. FIG. 4 is a main part of a different embodiment, and FIG. and b are cross-sectional views of different examples of forming gas vent grooves. 1... Cylinder block, 2... Matching part (mating surface), 3... Bore, 4, 4A, 4B... Gas vent groove, 8... Communication hole, 9... Crank case,
13, 13a... Metal gasket, 14... Cylinder head, 17... Oil reservoir, 20... Gas venting groove (tapered groove), 21... Gas venting groove (stepped groove).

Claims (1)

[Claims for Utility Model Registration] A metal gasket is interposed at the joining part of the cylinder block and the cylinder head to seal between the cylinder block and the cylinder head,
In an engine seal structure in which a gas vent groove is formed on the outer circumferential side of the bore in the mating part, the gas vent groove is connected to the upper part of the crankcase through a communication hole extending in the height direction of the engine through which lubricating oil does not flow. A seal structure for an engine, which communicates with at least one of a space or a space above the oil level of an oil reservoir in a head cover.