JP4292930B2 - Seal structure of sub chamber valve support in gas engine - Google Patents

Description

  The present invention mainly includes a gas engine that compresses and ignites natural gas fuel, and more specifically, a main chamber and a sub-combustion chamber, and a sub-chamber valve that opens and closes a communication hole that communicates the main combustion chamber and the sub-combustion chamber. The present invention relates to a seal structure for a sub chamber valve support in a gas engine.

  A gas engine equipped with a main combustion chamber, a sub-combustion chamber, and a sub-chamber valve that opens and closes a communication hole that communicates the main combustion chamber and the sub-combustion chamber is used when the pressure in the sub-combustion chamber is low during the intake stroke of the engine. The chamber valve is closed, gas fuel is supplied into the sub-combustion chamber having a low pressure, and the sub-chamber valve is opened at the later stage of the compression stroke. As a result, the intake air that has been compressed in the main combustion chamber and has reached a high temperature in the compression stroke flows into the sub-combustion chamber through the communication hole, and is compressed and ignited by rapidly mixing with the gas fuel in the sub-combustion chamber. The support portion that guides and supports the valve stem of the sub-chamber valve in such a gas engine is required to have a static sealing function for low-pressure fuel, a dynamic sealing function for high-temperature and high-pressure combustion gas, a cooling function, and a lubrication mechanism. That is, the support portion that guides and supports the valve stem of the sub chamber valve is required to have a static sealing function because the sub chamber valve is closed when supplying gas fuel to the sub combustion chamber at about 0.6 Mpa. At the same time, since the sub chamber valve is open at the time of combustion, a high-pressure combustion gas of up to about 150 Mpa acts, so that a dynamic sealing function is required. Further, it is necessary to supply an appropriate amount of lubricating oil to the sliding portion of the valve stem and the support portion of the sub chamber valve, and it is necessary to prevent the oil film from being cut and becoming dry.

As a sealing structure of the auxiliary chamber valve support part in the gas engine, a plurality of labyrinth fins are disposed in the valve stem at intervals in the axial direction, and the plurality of labyrinth fins are slidably inserted into the guide sleeve. Has been proposed. (For example, refer to Patent Document 1).
Further, as a seal structure of the sub chamber valve support portion in the gas engine, an elastic seal is extrapolated to the valve stem, and a piezoelectric element is disposed inside the elastic seal, so that the piezoelectric element corresponds to the pressure in the sub combustion chamber. There has also been proposed a method in which the pressure applied to the valve stem of the elastic seal is controlled by applying a voltage to. (For example, refer to Patent Document 2).
JP-A-8-28351 JP-A-8-121127

  Thus, the technique disclosed in Japanese Patent Application Laid-Open No. 8-28351 is intended to supplement the dynamic sealing function by the pressure reducing effect by the labyrinth, and has a sealed static sealing function. Not. Accordingly, the one disclosed in JP-A-8-28351 is provided with an elastic seal having a separate static sealing function. In addition, what is disclosed in Japanese Patent Application Laid-Open No. 8-28351 does not necessarily have a sufficient effect on the high fluctuating pressure of the combustion gas only by the pressure reducing effect by the labyrinth in the dynamic sealing function.

  The technique disclosed in Japanese Patent Application Laid-Open No. 8-121127 is intended to supplement the sealing function against pressure change by controlling the pressing force of the elastic seal according to the pressure in the sub chamber. It is not necessarily suitable for a high-pressure seal when reciprocating like a valve. That is, if the pressing force of the elastic seal is increased during the operation of the sub chamber valve, the frictional force increases and the sliding portion of the elastic seal may be damaged.

The present invention has been made in view of the above circumstances, the principal object is a dynamic sealing function of the static sealing function and high-temperature high-pressure combustion gas of the low-pressure fuel in the sub-chamber valve support portion of the gas engine It is providing the sealing structure which has.

In order to solve the main technical problem, according to the present invention,
“A main combustion chamber formed by a piston slidably disposed in a cylinder formed in the cylinder block and a cylinder head disposed on the upper surface of the cylinder block; and the main combustion chamber provided in the cylinder head A sub-combustion chamber communicated with the combustion chamber by a communication hole, a sub-chamber valve that is inserted through the sub-combustion chamber and opens and closes the communication hole, and a valve stem of the sub-chamber valve disposed in the cylinder head And a sub-chamber valve support portion in a gas engine in which gas fuel is supplied to the sub-combustion chamber when the sub-chamber valve closes the communication hole. The sealing structure of
A joint ring made of a plurality of heat-resistant metals disposed by fitting the valve stem to the lower stage of the support sleeve close to the auxiliary combustion chamber;
A combination packing comprising a resin ring that is disposed between the support sleeve and the valve stem above the plurality of abutment rings and is inserted into the valve stem, and an elastic ring that is inserted into the outer periphery of the resin ring. And further,
An annular groove is formed on the inner peripheral surface of the support sleeve between the plurality of joint rings and the combination packing. ''
A sub-chamber valve support portion sealing structure in a gas engine is provided.

The abutment ring is joined end surfaces opposed to each other in the predetermined temperature or higher with each other, it is not to demand that is configured to hold a predetermined gap between the outer peripheral surface of the valve stem. Further , it is desirable that a lubricating oil passage is formed on the upper side of the combination packing in the support sleeve. Further, the support sleeve is divided into three in the vertical direction, the combination packing is disposed on the upper first sleeve member, and the plurality of joint rings are disposed on the lower third sleeve member, and It is desirable that the annular groove is formed in the intermediate second sleeve member.

In the gas engine according to the present invention, the sub-chamber valve support seal structure is provided with a plurality of abutment rings capable of self-sealing so as to seal high-pressure combustion gas at the lower stage close to the sub-combustion chamber, and at the upper stage. A combination packing consisting of a resin ring and an elastic ring having a typical sealing function is disposed, and an annular groove is formed between the plurality of abutment rings and the combination packing, so that high-pressure combustion gas due to the labyrinth decompression effect Thus, the static sealing performance of the low-pressure fuel can be ensured.

  Hereinafter, a preferred embodiment of a seal structure for a sub-chamber valve support in a gas engine constructed according to the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view of a gas engine having a sub-chamber valve support portion sealing structure constructed according to the present invention. The illustrated gas engine includes a cylinder block 2 formed of cast iron or the like, and a cylinder head 3 formed of cast iron or the like disposed on the upper surface of the cylinder block 2. A cylinder 21 is formed in the cylinder block 2, and a piston 4 is slidably disposed in the cylinder 21. A circular recess 31 is formed on the lower surface of the cylinder head 3, and a head liner 5 formed in a reverse cup shape with ceramics is fitted into the circular recess 31. A main combustion chamber 5 a is formed between the head liner 5 and the piston 4. Although not shown, the cylinder head 3 is formed with an intake passage communicating with the main combustion chamber 5a and an exhaust passage. An intake valve is provided in the intake passage, and an exhaust valve is provided in the exhaust passage. Is arranged. Since this structure is the same as that of a normal diesel engine, the description thereof is omitted.

The head liner 5 in the illustrated embodiment includes a sub-combustion chamber 5b on the upper side of the upper wall thereof. A communication hole 51 is formed in the upper wall of the head liner 5 to communicate the main combustion chamber 5a and the auxiliary combustion chamber 5b. A gas fuel supply hole 52 is formed in the upper wall forming the sub-combustion chamber 5 b, and the gas fuel supply hole 52 is connected to the gas fuel supply pipe 6. The gas fuel supply hole 52 is provided with a fuel supply valve 7 that is operated in association with the reciprocation of the piston 4. The operation timing of the fuel supply valve 7 will be described in detail later. Further, a valve stem insertion hole 53 is formed on the same axis as the communication hole 51 on the upper wall forming the auxiliary combustion chamber 5b.

  The gas engine in the illustrated embodiment includes a sub chamber valve 8 that opens and closes a communication hole 51 that communicates the main combustion chamber 5a and the sub combustion chamber 5b. The sub chamber valve 8 includes a valve portion 81 formed so as to be seated on the valve seat 511 of the communication hole 51 and a valve stem 82 formed integrally with the valve portion 81. The support mechanism 10 is supported so as to be slidable in the axial direction. The support mechanism 10 includes a case 11 having a sleeve insertion hole 111. The lower end of the case 11 is attached to the cylinder head 3 with a fastening bolt 19 by pressing a gasket 54 disposed on the upper wall forming the sub-combustion chamber 5b.

The lower half of the support sleeve 12 that slidably supports the valve stem 82 of the sub chamber valve 8 in the axial direction is fitted into the sleeve insertion hole 111 of the case 11 described above. The support sleeve 12 will be described with reference to FIG. The support sleeve 12 in the illustrated embodiment is divided into a first sleeve member 121, a second sleeve member 122, and a third sleeve member 123. The first sleeve member 121, the second sleeve member 122, and the third sleeve member 123 are provided with holes 121A, 122A, and 123A through which the valve stem 82 is inserted, respectively. An annular fitting groove 121 b is formed at the lower end of the first sleeve member 121. The second sleeve member 122 includes a first fitting portion 122a that is formed in an upper portion and is fitted in an annular fitting groove 121b provided in the first sleeve member 121, and a second fitting formed in the lower portion. It consists of a joint part 122b and a flange part 122c provided between the first fitting part 122a and the second fitting part 122b and projecting in the radial direction. The third sleeve member 123 includes an annular first fitting groove 123a formed on the upper portion and fitted to the second fitting portion 122b of the second sleeve member 122, and the first fitting groove 123a. An annular second fitting groove 123b formed on the lower side and having a smaller diameter than the first fitting groove 123a is provided. The first spacer 13 is interposed between the step 123c of the first fitting groove 123a and the second fitting groove 123b in the third sleeve member 123 and the lower end of the second sleeve member 122. The second spacer 14 is disposed between the lower end of the third sleeve member 123 and the case 11.

Next, a seal structure formed between the first sleeve member 121, the second sleeve member 122, the third sleeve member 123, and the valve stem 82 constituting the support sleeve 12 will be described.
The lower rings close to the auxiliary combustion chamber 5 b, that is, between the second fitting groove 123 b of the third sleeve member 123 and the first spacer 13 and the lower end of the second sleeve member 122, the abutment rings 15, 15. Is arranged. The abutment ring 15 is made of a heat-resistant metal material such as incoloy, and includes a hole 151 into which the valve stem 82 is inserted as shown in FIG. 3, and a gap S between the end faces facing each other in the abutment portion. Is set to about 0.3 mm, for example. This gap S is formed between the end faces facing each other at a predetermined temperature (for example, 500 ° C.) or more by the high-pressure combustion gas (in-cylinder pressure) acting on the back surface of the abutment ring 15, and between the outer peripheral surface of the valve stem 82. It is desirable to set a value that holds a predetermined gap ( for example, a gap that exceeds 0 mm and is 0.02 mm or less ). The combination packing 16 is provided between the upper stage above the joint rings 15, 15 thus configured, that is, between the upper end of the second sleeve member 122 and the end surface of the fitting groove 121 b of the first sleeve member 121. Is arranged. The combination packing 16 includes a resin ring 17 and an elastic ring 18 that is fitted on the outer periphery of the resin ring 17. The resin ring 17 is made of a tetrafluoroethylene resin having excellent sliding characteristics. The elastic ring 18 is made of fluoro rubber. An annular groove 122 d is formed on the inner peripheral surface of the second sleeve member 122 disposed between the abutment rings 15 and 15 and the combination packing 16 .

The seal structure in the illustrated embodiment includes a lubricating oil passage 121 c formed on the upper side of the combination packing 16 in the first sleeve member 121. The lubricating oil passage 121 c communicates with a lubricating oil supply passage 112 formed in the case 11. The lubricating oil supply passage 112 is connected to lubricating oil supply means (not shown).

1, the valve spring retainer 91 is attached to the upper end portion of the valve stem 82 of the sub chamber valve 8, and the valve spring 90 is arranged between the valve spring retainer 91 and the case 11. It is installed. Accordingly, the sub chamber valve 8 is always urged upward by the valve spring 90 . The sub chamber valve 8 configured as described above is operated in association with the reciprocation of the piston 4 by a valve mechanism (not shown).

The gas engine in the illustrated embodiment is configured as described above. Hereinafter, refer also to FIG. 4 showing the opening and closing timings of the sub chamber valve 8 and the fuel supply valve 7 and the intake valve and exhaust valve (not shown). To explain.
When the sub chamber valve 8 is closed in the first half of the intake stroke of the engine and the fuel supply valve 7 is opened in the second half of the intake stroke, the gas fuel is supplied from the gas fuel supply pipe 6 through the gas fuel supply hole 52 to the sub combustion chamber 5b. The On the other hand, the air sucked into the main combustion chamber 5a in the intake stroke is compressed in the compression stroke and becomes high temperature. When the sub-chamber valve 8 is opened at the latter stage of the compression stroke, high-temperature air in the main combustion chamber 5a is jetted to the sub-combustion chamber 5b through the communication hole 51, and mixed with the gas fuel to ignite the gas fuel. The mixture of gas fuel and air ignited in the sub-combustion chamber 5b flows into the main combustion chamber 5a through the communication hole 51 in the expansion stroke, and causes the piston 4 to reciprocate by applying an explosion load to the piston 4 while burning.

  During operation of the gas engine described above, when gas fuel is supplied to the sub-combustion chamber 5b, gas fuel leaks from between the valve stem 82 of the sub-chamber valve 8 and the support sleeve 12. This gas fuel rises through the periphery of the abutment rings 15, 15, but is blocked by the resin ring 17 constituting the combination packing 16 and the elastic ring 18 inserted into the outer periphery of the resin ring 17, and further leaks upward. Is prevented. That is, the space between the outer periphery of the valve stem 82 is sealed by the resin ring 17, and the space between the resin ring 17 and the support sleeve 12 is sealed by the elastic ring 18. At this time, since the resin ring 17 is not elastically contacted with the outer periphery of the valve stem 82 by a strong pressure, there is no possibility that the resin ring 17 is damaged by a frictional force.

On the other hand, in the state where the sub chamber valve 8 is opened, the gas fuel mixed with the air which has been compressed in the compression stroke and becomes high temperature is combusted in the sub combustion chamber 5b. As a result, a part of the high-pressure combustion gas in the auxiliary combustion chamber 5 b leaks from between the valve stem 82 of the auxiliary chamber valve 8 and the support sleeve 12. Since this high-pressure combustion gas acts on the outer peripheral surfaces of the abutment rings 15, 15, the diameter of the abutment ring 15 is reduced, the gap with the valve stem 82 is reduced, and the circulation of the high-pressure combustion gas is suppressed. In the illustrated embodiment, when the abutment ring 15 reaches a predetermined temperature (for example, 500 ° C.) or higher, the pressure of the high-pressure combustion gas also increases, and the opposite end faces of the abutment portion of the abutment ring 15 are joined . Therefore, further reduction of the abutment ring 15 is prevented, and a predetermined gap ( for example, a gap of more than 0 mm and not more than 0.02 mm ) is maintained between the outer periphery of the valve stem 82 and the valve stem 82. There is no hug to the outer peripheral surface . Therefore, the sliding resistance does not increase with respect to the vertical movement of the valve stem 82, and there is no problem of wear.
Then, the inner peripheral surface of the second sleeve member 122 disposed between the packing 16 in combination with abutment rings 15 and 15 are formed annular grooves 122d. Since the combustion gas slightly leaking from the abutment rings 15 and 15 enters the annular groove 122d and the pressure drops, further upward leakage is suppressed. That is, in this seal structure, a slight amount of combustion gas passing through the gap between the valve stem 82 and the abutment ring 15 drops in the plurality of abutment rings 15 and further drops when flowing into the annular groove 122d. . A large fluid resistance is generated by the pressure reducing effect by such a labyrinth, and leakage of the combustion gas is substantially prevented. In this gas engine, the sub chamber valve 8 is closed in the first half of the intake stroke of the engine, and the pressure in the sub combustion chamber 5b is reduced. At this time, the combustion gas in the annular groove 122d flows into the low pressure sub combustion chamber 5b. leak. For this reason, since the inside of the annular groove 122d does not become a high pressure and a slight flow of combustion gas always occurs, the sealing effect by the labyrinth is always ensured. Further, since a slight amount of combustion gas is stored in the annular groove 122d and does not flow to the upper combination packing 16, it is not damaged even if the combination packing 16 is resin.

  In the illustrated embodiment, the lubricating oil passage 121c is formed above the combination packing 16 in the first sleeve member 121, and the lubricating oil is supplied from the side surface of the first sleeve member 121. The lubricating oil flows to the cylinder head 3 side through between the first sleeve member 121 and the valve stem 82 to cool the valve stem 82, and the inner peripheral surface of the resin ring 17 constituting the combination packing 16 Appropriate lubricating oil can always be supplied to the sliding portion between the valve stem 82 and the outer peripheral surface.

As described above, in the seal structure of the sub-chamber valve support portion in the gas engine according to the present invention , the abutment rings 15 and 15 capable of self-sealing for sealing high-pressure combustion gas are arranged in the lower stage near the sub-combustion chamber 5b. The combination packing 16 composed of a resin ring 17 having a static sealing function and an elastic ring 18 is disposed on the upper stage, and an annular groove is formed between the plurality of joint rings and the combination packing. Therefore, the dynamic sealing performance of the high-pressure combustion gas and the static sealing performance of the low-pressure fuel can be ensured. The annular groove between the abutment ring and the combination packing also serves to prevent the high pressure combustion gas from flowing into the combination packing and damaging it.
In the illustrated embodiment, the lubricating oil passage 121c is formed on the upper side of the combination packing 16 in the support sleeve 12 to supply the lubricating oil, so that the valve stem 82 can be cooled and the combination packing 16 can be cooled. A lubricating function can be ensured by supplying an appropriate amount of lubricating oil to the sliding portion between the inner peripheral surface of the resin ring 17 and the outer peripheral surface of the valve stem 82.

Sectional drawing of the gas engine provided with the seal structure of the subchamber valve support part comprised according to this invention. Sectional drawing which expands and shows the seal structure of the subchamber valve support part of the gas engine shown in FIG. The top view of the abutment ring which comprises the sealing structure of the sub chamber valve support part shown in FIG . Explanatory drawing which shows the opening / closing timing of each valve of the gas engine shown in FIG.

Explanation of symbols

2: cylinder block 21: cylinder 3: cylinder head 4: piston 5: head liner 5a: main combustion chamber 5b: auxiliary combustion chamber 51: communication hole 52: gas fuel supply hole 53: valve stem insertion hole 6: gas fuel supply pipe 7: Fuel supply valve 8: Sub chamber valve 81: Valve portion 82: Valve stem 91: Valve spring retainer 92: Valve spring 10: Support mechanism 11: Case 111: Sleeve insertion hole 112: Lubricating oil supply passage 12: Support sleeve 121 : First sleeve member 121c: lubricating oil path 122: second sleeve member 123: third sleeve member
15 : Joint ring 16: Combination packing 17: Resin ring 18: Elastic ring

Claims (4)

A main combustion chamber formed by a piston slidably disposed in a cylinder formed in the cylinder block and a cylinder head disposed on an upper surface of the cylinder block, and the main combustion provided in the cylinder head A sub-combustion chamber communicated with the chamber by a communication hole; a sub-chamber valve that is inserted through the sub-combustion chamber to open and close the communication hole; and a valve stem of the sub-chamber valve disposed in the cylinder head. A support sleeve for slidably supporting the sub-combustion chamber, wherein the sub-combustion chamber has a sub-chamber valve support portion in a gas engine to which gas fuel is supplied when the sub-chamber valve closes the communication hole . A seal structure,
A joint ring made of a plurality of heat-resistant metals disposed by fitting the valve stem to the lower stage of the support sleeve close to the auxiliary combustion chamber;
A combination packing comprising a resin ring that is disposed between the support sleeve and the valve stem above the plurality of abutment rings and is inserted into the valve stem, and an elastic ring that is inserted into the outer periphery of the resin ring. And further,
An annular groove is formed in an inner peripheral surface between the plurality of abutment rings and the combination packing in the support sleeve, and a seal structure for a sub chamber valve support in a gas engine.   2. The sub-chamber valve in the gas engine according to claim 1, wherein the abutment ring is configured such that end faces facing each other at a predetermined temperature or more are joined to each other and a predetermined gap is maintained between the end face and the outer peripheral surface of the valve stem. Support structure seal structure.   2. The seal structure for a sub chamber valve support portion in a gas engine according to claim 1, wherein a lubricating oil passage is formed above the combination packing in the support sleeve. The support sleeve is divided into three in the vertical direction, the combination packing is disposed on the upper first sleeve member, the plurality of joint rings are disposed on the lower third sleeve member, and the annular The seal structure of the sub-chamber valve support part in the gas engine according to claim 1, wherein the groove is formed in the intermediate second sleeve member .

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