JP5676418B2 - Boot seal structure of variable compression ratio engine - Google Patents

Description

  The present invention relates to a boot seal structure disposed in a variable compression ratio engine.

  The inventors disclosed in Patent Document 1 as a boot seal structure disposed in a relative displacement type variable compression ratio engine that the bellows-shaped deformed portion of the boot seal is deformed outward by the pressure of blow-by gas. A boot seal structure that can regulate the amount of deformation to a predetermined deformation amount was proposed.

  As shown in FIG. 6, the boot seal structure 900 includes a cylindrical boot seal 910 having a deformable portion 912 and a deformation preventing plate 920 disposed outside the boot seal 910. The boot seal 910 is sandwiched between the cylinder block 1 and the cylinder head 3 at the upper fixing portion 914, and the lower fixing portion 916 is sandwiched between the crankcase 2 and the deformation prevention plate 920 so that the cylinder block 1 and the crankcase 2 It is fixed so as to cover the gap.

  According to the boot seal structure 900, the deformation prevention plate 920 can restrict the outward deformation of the deformable portion 912 to a predetermined deformation amount, so that the deformable portion 912 is prevented from being ruptured or damaged. The durability of the boot seal 910 can be improved.

JP 2011-117366 A

  In the boot seal structure 900 as described above, a deformation space 940 is required between the deformation prevention plate 920 and the boot seal 910 so that the deformable portion 912 can be deformed and moved by expansion and contraction of the boot seal 910 or internal pressure. However, since the deformation space 940 is open to the outside, dust and oil and moisture enter from the outside and adhere to the boot seal 910 and stay in the deformation space 940 to increase the durability of the boot seal 910. There is a risk of lowering.

  The present invention has been made in view of the above circumstances, and a boot seal having a bellows-cylindrical deformed portion disposed so as to cover between a cylinder block and a crankcase of a relative displacement type VCR engine, An object of the present invention is to provide a boot seal structure having a deformation preventing plate that restricts deformation of the deforming portion and capable of avoiding accumulation of dust and oil moisture between the boot seal and the deformation preventing plate.

  Hereinafter, each means suitable for solving the above-described problems will be described with additional effects and the like as necessary. The boot seal structure of the variable compression ratio engine of the present invention is a cylindrical shape made of an elastically deformable material attached to a variable compression ratio engine that changes the relative position between the cylinder block and the crankcase to change the volume of the combustion chamber. A cylindrical boot seal having an upper fixed portion fixed to the cylinder block, a lower fixed portion fixed to the crankcase, and an outward of the deformed portion disposed outside the boot seal A boot seal structure of a variable compression ratio engine comprising a deformation prevention plate that restricts deformation to a predetermined deformation amount, and extends from an upper fixing portion or a lower fixing portion of the boot seal, and includes a deformation prevention plate and a boot seal. A sub cover is provided to cover the gap. According to such a configuration, it is possible to prevent dust and oil moisture from entering between the boot seal and the deformation prevention plate.

  In the boot seal structure of the variable compression ratio engine of the present invention, the sub-cover includes a fixed portion fixed to the upper fixed portion or the lower fixed portion of the boot seal, an expansion / contraction portion that expands and contracts following the deformation of the boot seal, and deformation prevention. It is preferable to provide an engaging portion that engages with an edge of the plate. According to such a configuration, the sub cover is engaged with the deformation prevention plate and covers the gap between the boot seal and the deformation prevention plate, that is, the sub cover can follow the deformation of the boot seal well while maintaining the sealing performance. Can do.

  In the boot seal structure of the variable compression ratio engine of the present invention, the sub-cover includes a flange portion that covers the gap and a locking portion that is continuous with the outer peripheral edge of the flange portion and locks to the edge of the deformation prevention plate. Is desirable. According to such a configuration, even if the cylinder block is displaced up and down with respect to the crankcase, the sub cover can maintain the state in which the locking portion is locked to the deformation prevention plate. Opening between the covers can be prevented.

  In the boot seal structure of the variable compression ratio engine of the present invention, it is desirable that the deformation preventing plate has a vent hole that communicates the gap with the outside. According to such a configuration, the pressure in the gap can always be maintained at atmospheric pressure, so that deformation of the deformed portion due to expansion / contraction of the boot seal and change in internal pressure is not hindered.

  Moreover, in the boot seal structure of the variable compression ratio engine of the present invention, it is preferable that the deformation preventing plate includes an oil moisture removing unit that communicates the gap and the outside and discharges the oil and moisture staying in the gap to the outside. According to such a configuration, the oil moisture flowing into the gap can be discharged to the outside via the oil moisture removing means. Therefore, oil and water do not stay in the gap, and the durability of the boot seal is not reduced.

  According to the present invention, a boot seal having a bellows-cylindrical deformable portion disposed so as to cover between a cylinder block and a crankcase of a relative displacement type VCR engine, and deformation prevention that restricts deformation of the deformable portion. In the boot seal structure having the plate, it is possible to provide a boot seal structure capable of preventing dust and oil from being accumulated between the boot seal and the deformation preventing plate.

It is a perspective view of the boot seal structure in a 1st embodiment. It is the fragmentary sectional view cut | disconnected by the AA line in FIG. It is a fragmentary sectional view of the boot seal structure in a 2nd embodiment. It is a fragmentary sectional view of the boot seal structure in a 3rd embodiment. It is a fragmentary sectional view of the boot seal structure in a 3rd embodiment. It is a fragmentary sectional view of the conventional boot seal structure.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a boot seal structure for a variable compression ratio engine of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view of a boot seal structure in the present embodiment, and FIG. 2 is a partial cross-sectional view taken along line AA in FIG.

  As shown in FIG. 2, the boot seal structure 10 of the present embodiment includes a boot seal 200 disposed so as to cover between the cylinder block 1 and the crankcase 2 of the relative displacement type VCR engine, and a deformation prevention plate 300. And a sub-cover 500 that covers a gap (hereinafter referred to as a deformation space) 40 between the boot seal 200 and the deformation prevention plate 300.

  That is, the boot seal structure 10 of the present embodiment is the one in which the sub cover 500 is provided so as to cover the gap 940 between the boot seal 910 and the deformation preventing plate 920 in the conventional boot seal structure 900 shown in FIG. is there. Therefore, except the sub cover 500, it can be comprised similarly to the boot seal structure 900 used as a prior art. FIG. 1 shows a state where the cylinder head 3 of the relative displacement type VCR engine is removed, and in FIG. 2, the cylinder head 3 is shown by a virtual line.

  The boot seal 200 has an accordion tube-like deformed portion 202 having a protruding inward portion, and an upper fixed portion that is provided at the upper opening end of the deformable portion 202 and is sandwiched between the cylinder head 3 and the cylinder block 1. Part 204 and a lower fixing part 206 provided at the lower opening end of the deforming part 202 and sandwiched between the crankcase 2 and the deformation preventing plate 300.

  The deformation part 202 is formed of an elastically deformable material having flexibility and pressure resistance. Examples of the material having flexibility and pressure resistance include rubber (FKM, AEM) and resin (PFA, FEP), or thermoplastic elastomer (TPEE) which is an intermediate composition of rubber and resin. . Further, the chemical resistance of the deformable portion 202 may be improved by forming a film such as a fluororesin on the inner surface of the deformable portion 202.

  The upper fixing portion 204 is an annular body having a lower surface parallel to the upper surface of the cylinder block 1, and is formed integrally with the deforming portion 202. The upper fixing portion 204 is formed continuously with the outer peripheral edge of the metal cylinder head gasket 4, and the cylinder head gasket 4 is provided with a plurality of piston openings 42 and a plurality of peripheral member openings 44. ing.

  The lower fixing portion 206 is an annular body having a lower surface parallel to the upper surface of the crankcase 2, and is formed integrally with the deforming portion 202. An annular protrusion 207 is formed on the lower surface of the lower fixing portion 206 over the entire circumference of the lower fixing portion 206. The ridge 207 is fitted into a groove 22 formed on the upper surface of the crankcase 2 over the entire circumference.

  The deformation prevention plate 300 is a cylindrical body having an L-shaped cross section having a lower surface parallel to the upper surface of the crankcase 2, and includes a base portion 302 and an extending portion 304 extending upward from the inner peripheral edge of the base portion 302. The base 302 is provided with a discharge groove 303 that discharges oil and moisture that has entered the deformation space 40 to the outside. In addition, the discharge groove 303 is an oil moisture removing means in the present embodiment.

  In addition, the extending portion 304 has a vent hole 305 that allows the deformation space 40 to communicate with the outside. By providing the vent hole 305, it is possible to reduce the pressure change in the deformation space 40 due to the expansion and contraction of the deformation portion 202 and the internal pressure change of the engine. The deformation preventing plate 300 is fastened to the upper surface of the crankcase 2 by a bolt 60 and also functions as a retainer that sandwiches the lower fixing portion 206 with the crankcase 2. The deformation preventing plate 300 is made of a metal plate such as a galvanized steel plate or aluminum, or a resin molded product such as a phenol resin.

  The sub-cover 500 is made of an elastically deformable material, and has a connection portion 502 connected to the upper fixing portion 204, a bellows cylindrical expansion / contraction portion 504, and a cylindrical engagement hanging from the periphery of the expansion / contraction portion 504. It is the cylindrical body in which the part 506 was integrally formed. In the present embodiment, the connection portion 502 is a fixed portion.

  The connection portion 502 protrudes outward from the outer peripheral edge of the upper fixing portion 204 and is formed in an annular shape, and is formed integrally with the upper fixing portion 204. Further, a groove portion 507 is provided at the lower end portion of the engaging portion 506 over the entire circumference, and the upper end edge of the extending portion 304 of the deformation preventing plate 300 is fitted into the groove portion 507 so that the sub cover 500 and the deformation preventing plate are disposed. 300 is engaged.

  The expansion / contraction part 504 of the sub cover 500 is formed of a material having flexibility like the deformation part 202 of the boot seal 200. Examples of the material include thermoplastic elastomer (TPEE) and rubber (FKM, AEM) similar to the deformed portion 202 of the boot seal 200.

  As described above, the sub cover 500 extending from the upper fixing portion 204 and the deformation preventing plate 300 are engaged, so that the opening of the deformation space 40 is covered over the entire circumference. Thereby, it is possible to reliably prevent dust and oil / moisture from entering the deformation space 40 from the outside. Further, by forming the sub cover 500 integrally with the boot seal 200, the number of parts of the boot seal structure 10 can be reduced.

Second Embodiment
FIG. 3 shows a partial cross-sectional view of the boot seal structure 12 in the present embodiment. In FIG. 3, the same parts as those in FIG.

  In the boot seal structure 12 of the present embodiment, the deformation preventing plate 310 is formed continuously with the upper fixing portion 214 of the boot seal 210, and the lower fixing portion 216 of the boot seal 210 is connected to the crankcase 2 by the retainer 70. It is fixed to the upper surface of the. A vent hole 315 is formed in the deformation preventing plate 310. The retainer 70 has a discharge groove 73 cut away. In addition, the discharge groove 73 is an oil moisture removing means in the present embodiment.

  The sub cover 510 extends upward from the lower fixing portion 216 of the boot seal 210 and is engaged with the lower end edge of the deformation preventing plate 310 to cover the deformation space 40. The sub-cover 510 is made of an elastically deformable material, and has an annular fixing portion 518, a bellows cylindrical expansion / contraction portion 514, and a cylindrical engagement portion 516 extending upward from the peripheral edge of the expansion / contraction portion 514. Are integrally formed.

  The fixing portion 518 is integrally formed on the upper surface of the lower fixing portion 216 of the boot seal 210 and is sandwiched between the lower fixing portion 216 and the retainer 70. The outer peripheral edge of the fixing portion 518 is formed so as to be located on the inner side of the inner peripheral surface of the groove portion 22 into which the protruding portion 217 of the lower fixing portion 216 formed on the upper surface of the crankcase 2 is fitted. By forming in this way, the lower fixing portion 216 together with the fixing portion 518 can be firmly fixed to the crankcase 2.

  A groove portion 517 is provided at the upper end portion of the engagement portion 516 over the entire circumference, and the lower end edge of the deformation prevention plate 310 is fitted into the groove portion 517 so that the sub cover 510 and the deformation prevention plate 310 are engaged. ing. In addition, the expansion-contraction part 514 of the sub cover 510 is formed with the material which has the softness | flexibility similar to the sub cover 500 of 1st Embodiment.

  By engaging the sub cover 510 and the deformation preventing plate 310, the deformation space 40 is covered over the entire circumference. Thereby, it is possible to reliably prevent dust and oil / moisture from entering the deformation space 40 from the outside. In the figure, reference numeral 80 denotes an inner deformation prevention plate that regulates the amount of deformation of the boot seal 20 toward the inside of the deforming portion 212.

<Third Embodiment>
FIG. 4 shows a partial cross-sectional view of the boot seal structure 14 in the present embodiment. In FIG. 4, the same parts as those in FIG.

  In the boot seal structure 14 of the present embodiment, the deformation preventing plate 320 is formed such that the extending portion 324 extends to the upper fixing portion 224 of the boot seal 220. That is, the extending portion 324 of the deformation preventing plate 320 can surround the entire deforming portion 222 of the boot seal 220 in a state where the combustion chamber volume in which the cylinder block 1 is farthest from the crankcase 2 in the cylinder axial direction is maximum. Is formed. Therefore, the deformation space 40 can be covered from the outside by closing the gap D between the outer peripheral edge of the upper fixing portion 224 of the boot seal 220 and the edge of the extending portion 324 of the deformation preventing plate 320.

  The deformation part 222 of the boot seal 220 is formed to have a larger curvature than the bent part of the deformation part 202 of the first embodiment. This makes it difficult for wrinkles to be applied to the deformed portion 222, and allows the stress acting on the deformed portion 222 to be dispersed over a wide range. Therefore, the durability of the boot seal 220 can be further improved.

  In the present embodiment, the sub cover 520 is formed integrally with the upper fixing portion 224 of the boot seal 220 and includes a flange portion 522 and a locking portion 524. The flange portion 522 protrudes outward substantially horizontally from the outer peripheral edge of the upper fixing portion 224, and the engaging portion 524 extends outward along the outer surface of the extending portion 324 of the deformation preventing plate 320. It is formed continuously.

  The sub-cover 520 configured in this manner can easily lock the locking portion 524 to the upper end edge of the extending portion 324 of the deformation preventing plate 320, so that the gap D is closed and deformed over the entire circumference. The space 40 can be covered.

  When the cylinder block 1 is lowered with respect to the crankcase 2 and the combustion chamber volume is reduced, the upper fixing portion 224 of the boot seal 220 is lower than the upper end edge of the extending portion 324 of the deformation preventing plate 320. . At this time, as shown in FIG. 5, the flange portion 522 can be deformed while maintaining the state where the locking portion 524 is locked to the upper end edge of the extending portion 324. In this way, the flange portion 522 has a relatively small rigidity such that, for example, the flange portion 522 is formed thin so that the locking portion 524 can be deformed while maintaining the state of being locked to the upper end edge of the extending portion 324. The sub cover 520 may be formed as described above. In FIG. 4, 325 is a vent hole and 323 is a discharge groove (oil moisture removing means).

  The boot seal structure of the variable compression ratio engine of the present invention is not limited to the above-described embodiment, and various modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention. It goes without saying that it can be carried out at.

  For example, in each of the embodiments described above, the sub cover and the boot seal are integrally formed, but the sub cover may be formed as a separate body. A separate cover can be easily formed. In each of the above-described embodiments, the oil and moisture removing means for discharging the oil and moisture staying in the gap to the outside is the discharge groove cut on the bottom surface of the deformation prevention plate or the retainer. It is good also as the discharge hole drilled so that it may communicate with the outside at the position.

  The present invention can be suitably used as a boot seal structure disposed in a variable compression ratio engine.

1: Cylinder block 2: Crank case 3: Cylinder head 10, 12, 14: Boot seal structure 200, 210, 220: Boot seal 202, 212, 222: Deformed portion 204, 214, 224: Upper fixed portion 206, 216, 226: Lower fixing portion 300, 310, 320: Deformation prevention plate 40: Gap (deformation space) 500, 510, 520: Sub cover 502, 518: Fixing portion 504, 514: Extending portion 506, 516: Engaging portion 522 : Flange part 524: Locking part 305, 315, 325: Vent hole 303, 73, 323: Discharge groove (oil moisture removing means)

Claims (5)

A cylinder-shaped deformed portion made of an elastically deformable material and an upper fixed portion that is fixed to the cylinder block, which is attached to a variable compression ratio engine that changes the volume of the combustion chamber by changing the relative position between the cylinder block and the crankcase. A cylindrical boot seal having a lower portion and a lower fixing portion fixed to the crankcase, and the outward deformation of the deformable portion that is disposed outside the boot seal is regulated to a predetermined deformation amount. A variable compression ratio engine boot seal structure comprising a deformation prevention plate,
A boot seal structure for a variable compression ratio engine, comprising a sub-cover that extends from the upper fixing portion or the lower fixing portion of a boot seal and covers a gap between the deformation prevention plate and the boot seal.   The sub-cover is engaged with the upper fixed portion of the boot seal or the fixed portion fixed to the lower fixed portion, the expansion / contraction portion that expands and contracts following the deformation of the boot seal, and the edge of the deformation prevention plate. The boot seal structure of the variable compression ratio engine according to claim 1, further comprising an engaging portion that performs the operation.   2. The variable compression ratio engine boot according to claim 1, wherein the sub-cover includes a flange portion that covers the gap and an engaging portion that is continuous with an outer peripheral edge of the flange portion and engages with an end edge of the deformation preventing plate. Seal structure.   The boot seal structure of the variable compression ratio engine according to any one of claims 1 to 3, wherein the deformation prevention plate has a vent hole that communicates the gap with the outside.   5. The variable compression ratio engine according to claim 1, wherein the deformation prevention plate includes oil moisture removing means that communicates the gap with the outside and discharges oil moisture remaining in the gap to the outside. Boot seal structure.

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