JP2020159299A - Seal structure of internal combustion engine - Google Patents

Abstract

To reduce an abrasion loss.SOLUTION: A seal structure includes a circular oil seal 70 disposed at the radial inner side of combustion chambers A to D. A center 70C of the seal member 70 is offset relative to a rotation center axis AX of a first piston member and a second piston member.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a seal structure of an internal combustion engine.

Japanese Patent Application Laid-Open No. 2006-521490 (Patent Document 1) includes a first rotating member having a leading blade and a second rotating member having a trailing blade, and the leading blade and the trailing blade rotate. It is described that in the rotary blade type motor that completes the intake stroke, the compression stroke, the work stroke, and the exhaust stroke each time, a ring seal is provided between the first rotating member and the second rotating member. There is.

Special Table 2006-521490

When the circular seal member is arranged concentrically with the center of rotation of the rotating member, the seal member continues to slide with respect to the same portion of the rotating member. Therefore, there is a concern that the surface of the rotating member that comes into contact with the seal member is likely to be worn.

The present disclosure provides a seal structure for an internal combustion engine that can reduce the amount of wear.

According to the present disclosure, a sealing structure used for an internal combustion engine is provided. The internal combustion engine includes a housing, a first piston member rotatably supported in the housing about the rotation center axis, and a second piston member rotatably supported in the housing about the rotation center axis. Includes. The housing, the first piston member, and the second piston member form a combustion chamber for burning fuel. The first piston member has an annular facing surface facing the second piston member inside the combustion chamber in the radial direction. The seal structure includes a circular seal member arranged radially inside the combustion chamber. The center of the seal member is eccentric with respect to the rotation center axis.

The area in which the seal member slides with respect to either the first piston member or the second piston member is increased, the area in contact with the seal member during sliding is increased, and the same portion may slide repeatedly. It has been avoided. Therefore, the amount of wear on the contact surface of the seal member can be reduced.

In the above seal structure, the seal member is an oil seal that seals the lubricating oil. The oil seal is pressed against the first piston member and the second piston member with a force larger than that of the gas seal. Wear is more likely to occur on the contact surface of the oil seal. Therefore, it is possible to more effectively reduce the wear by applying the configuration in which the center is shifted from the rotation center axis to the oil seal.

According to the seal structure according to the present disclosure, the amount of wear can be reduced.

It is a perspective view which shows the structure of the internal combustion engine of an embodiment. It is a perspective view of the 1st piston member and the 2nd piston member. It is a schematic diagram for demonstrating the operation of a combustion chamber and an engine. It is the schematic which looked at the 1st piston member and a seal structure in the axial direction. It is a schematic cross-sectional view which shows the 1st example of the contact state between a 1st piston member and a 2nd piston member, and an oil seal. It is a schematic cross-sectional view which shows the 2nd example of the contact state between a 1st piston member and a 2nd piston member and an oil seal. It is the schematic which saw the 1st piston member and the seal structure which concerns on 2nd Embodiment in the axial direction.

Hereinafter, embodiments will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are the same. Therefore, detailed explanations about them will not be repeated.

[First Embodiment]
<Outline configuration of engine 2>
FIG. 1 is a perspective view showing a configuration of an internal combustion engine according to an embodiment. The internal combustion engine of the embodiment is a rotary piston type engine 2. For example, gas, gasoline, light oil, or the like is used as the fuel for the engine 2. The engine 2 includes a housing 4, an intake pipe 6, an exhaust pipe 8, an injector 10, a throttle motor 14, a first output shaft 16, and a second output shaft 18.

One end of the intake pipe 6 is connected to an intake port (not shown) of the housing 4. For example, an air cleaner (not shown) is connected to the other end of the intake pipe 6. The air cleaner removes foreign matter from the air sucked from the outside of the engine 2. While the engine 2 is operating, the air sucked from the air cleaner flows through the intake pipe 6. The air flowing through the intake pipe 6 circulates in the intake port of the housing 4.

The intake pipe 6 is provided with a throttle valve that limits the flow rate of air flowing through the intake pipe 6. The throttle motor 14 adjusts the opening degree of the throttle valve.

The injector 10 is provided on the upstream side of the throttle valve of the intake pipe 6 and injects fuel (for example, gas) into the intake pipe 6. The injected fuel is mixed with air in the intake pipe 6 and flows to the intake port of the housing 4.

As shown in FIG. 1, the outer peripheral portion of the housing 4 is formed in a cylindrical shape, and the inner peripheral portion thereof is also formed in a cylindrical shape. The housing 4 houses a first piston member connected to the first output shaft 16 and a second piston member connected to the second output shaft 18 inside the housing 4.

One end of the exhaust pipe 8 is connected to an exhaust port (not shown) of the housing 4. An exhaust treatment device (not shown) is connected to the other end of the exhaust pipe 8, for example. During the operation of the engine 2, the exhaust generated by the combustion in the housing 4 flows from the exhaust port of the housing 4 to the exhaust pipe 8. The exhaust gas flowing through the exhaust pipe is purified by the exhaust treatment device and discharged to the outside of the engine 2.

Both the first output shaft 16 and the second output shaft 18 rotate due to the combustion of fuel in the housing 4. The first output shaft 16 and the second output shaft 18 are connected to, for example, a rotating shaft of a motor generator (not shown). This motor generator is, for example, a three-phase AC rotary electric machine.

<Internal structure of engine 2>
Next, an example of the internal structure of the engine 2 will be described. FIG. 2 is a perspective view of the first piston member 24 and the second piston member 28. As shown in FIG. 2, the first piston member 24 and the second piston member 28 are housed in the housing 4 in combination. The first piston member 24 includes a first rotating body 24a, a first wall surface member 24b, and a first rotating shaft portion 24s. The second piston member 28 includes a second rotating body 28a, a second wall surface member 28b, and a second rotating shaft portion 28s.

The first rotating shaft portion 24s and the second rotating shaft portion 28s are rotatably supported by bearings (not shown) provided in the housing 4. As a result, the first piston member 24 and the second piston member 28 are rotatably supported by the housing 4. The first rotating body 24a and the second rotating body 28a have the same rotation center axis AX. The first rotating body 24a and the second rotating body 28a can rotate about the rotation center axis AX. The first rotating body 24a and the second rotating body 28a are provided so that one end surface of the first rotating body 24a and one end surface of the second rotating body 28a face each other in the axial direction.

In the description of the present specification, the direction parallel to the rotation center axis AX is referred to as an axial direction, the direction along the circumference centered on the rotation center axis AX is referred to as a circumferential direction, and the direction orthogonal to the rotation center axis AX. Is referred to as the radial direction. In the radial direction, the side closer to the rotation center axis AX is referred to as the inner side, and the side away from the rotation center axis AX is referred to as the outer side.

The first rotating body 24a and the second rotating body 28a are formed so as to have a slope portion in the cross section including the rotation central axis AX. As a result, in a state where the first rotating body 24a and the second rotating body 28a are combined, a recess having a V-shaped cross section is formed in the circumferential direction between the first rotating body 24a and the second rotating body 28a. Is formed in.

The first wall surface member 24b is provided so as to extend radially outward from the slope portion of the first rotating body 24a and extend axially toward the slope portion of the second rotating body 28a. There is. The first wall surface member 24b is composed of two triangular plate-shaped members. The two triangular plate-shaped members of the first wall surface member 24b are arranged at positions symmetrical with respect to the rotation center axis AX.

The second wall surface member 28b is provided so as to extend radially outward from the slope portion of the second rotating body 28a and extend axially toward the slope portion of the first rotating body 24a. There is. The second wall surface member 28b is composed of two triangular plate-shaped members having the same shape as the plate-shaped member constituting the first wall surface member 24b described above. The two triangular plate-shaped members of the second wall surface member 28b are arranged at positions symmetrical with respect to the rotation center axis AX.

The triangular plate-shaped members of the first wall surface member 24b and the second wall surface member 28b are the first rotating body 24a and the first rotating body 24a in a state where the first piston member 24 and the second piston member 28 are housed in the housing 4. It is formed so as to match the triangular cross-sectional shape formed by the V-shaped recess between the two rotating bodies 28a and the inner peripheral surface of the housing 4.

The first wall surface member 24b is fixed to the slope portion of the first rotating body 24a on one side of the triangle. One side of the triangle of the first wall surface member 24b faces the inner peripheral surface of the housing 4. One side of the triangle of the first wall surface member 24b faces the slope portion of the second rotating body 28a.

The second wall surface member 28b is fixed to the slope portion of the second rotating body 28a on one side of the triangle. One side of the triangle of the second wall surface member 28b faces the inner peripheral surface of the housing 4. One side of the triangle of the second wall surface member 28b faces the slope portion of the first rotating body 24a.

The first output shaft 16 is connected to the first rotating shaft portion 24s of the first piston member 24 so that the rotation center axes coincide with each other. A one-way clutch is provided between the first rotating body 24a and the housing 4. This one-way clutch allows rotation of the first piston member 24 in the housing 4 only in a predetermined rotation direction, and suppresses rotation in a direction opposite to the predetermined rotation direction.

The second output shaft 18 is connected to the second rotating shaft portion 28s of the second piston member 28 so that the rotation center axes coincide with each other. A one-way clutch is provided between the second rotating body 28a and the housing 4. This one-way clutch allows rotation of the second piston member 28 in the housing 4 only in a predetermined rotation direction, and suppresses rotation in a direction opposite to the predetermined rotation direction.

<Combustion chamber>
FIG. 3 is a schematic diagram for explaining the operation of the combustion chambers A to D and the engine 2. FIG. 3 schematically shows a cross section orthogonal to the rotation center axis AX in the central portion of the housing 4 (for example, the contact portion between the first rotating body 24a and the second rotating body 28a). As shown in FIG. 3, four combustion chambers A to D for burning fuel are formed in the housing 4 by the housing 4, the first piston member 24, and the second piston member 28.

The combustion chambers A to D are the inner peripheral surface of the housing 4, the slope portion of the first wall surface member 24b and the first rotating body 24a of the first piston member 24, and the second wall surface member 28b of the second piston member 28, respectively. And defined by the slope portion of the second rotating body 28a. The first wall surface member 24b and the second wall surface member 28b form a wall surface in the circumferential direction of the combustion chambers A to D. The two combustion chambers adjacent to each other in the circumferential direction are separated by a first wall surface member 24b and a second wall surface member 28b.

In FIG. 3, the one-way clutch described with reference to FIG. 2 suppresses the counterclockwise rotation of the first piston member 24 and the second piston member 28, and allows the clockwise rotation.

In the combustion chamber A shown in FIG. 3, the air-fuel mixture of the compressed air and the fuel becomes an expansion stroke in which the air-fuel mixture is ignited by self-ignition. That is, when the fuel burns in the combustion chamber A, the counterclockwise movement of the first piston member 24 is suppressed by the one-way clutch, so that only the second piston member 28 is maintained while the rotational position of the first piston member 24 is maintained. Rotates in the direction of the dashed arrow, and the volume of the combustion chamber A increases as the gas in the combustion chamber A expands.

In the combustion chamber B shown in FIG. 3, the expanded exhaust gas is discharged from the exhaust pipe 8. That is, when the second piston member 28 rotates in the direction of the broken arrow arrow due to the combustion of fuel in the combustion chamber A, the rotational position of the first piston member 24 is maintained, so that the volume of the combustion chamber B decreases. At this time, the combustion chamber B communicates with the exhaust pipe 8. Therefore, the exhaust gas in the combustion chamber B is discharged to the exhaust pipe 8 as the volume of the combustion chamber B decreases.

In the combustion chamber C shown in FIG. 3, the intake stroke is such that the air-fuel mixture is sucked from the intake pipe 6. That is, when the second piston member 28 rotates in the direction of the broken arrow arrow due to the combustion of fuel in the combustion chamber A, the rotational position of the first piston member 24 is maintained, so that the volume of the combustion chamber C increases. At this time, the combustion chamber C communicates with the intake pipe 6 while the second piston member 28 is rotating in the direction of the broken line arrow. Therefore, as the volume of the combustion chamber C increases, the air-fuel mixture is sucked into the combustion chamber C from the intake pipe 6.

In the combustion chamber D shown in FIG. 3, the compression stroke is such that the air-fuel mixture sucked from the intake pipe 6 is compressed. That is, when the second piston member 28 rotates in the direction of the broken arrow arrow due to the combustion of fuel in the combustion chamber A, the rotational position of the first piston member 24 is maintained, so that the volume of the combustion chamber D decreases. At this time, since the combustion chamber D does not communicate with either the intake pipe 6 or the exhaust pipe 8, the air-fuel mixture in the combustion chamber D is compressed by the decrease in the volume of the combustion chamber D.

Then, when a clockwise force acts on the first piston member 24 due to the increase in the pressure in the combustion chamber D, the first piston member 24 rotates, and the positions of the first piston member 24 and the second piston member 28 are located. The relationships will be swapped.

In this way, each time combustion is performed in any of the combustion chambers A to D, the first piston member 24 and the second piston member 28 rotate alternately to operate the engine 2.

<Seal structure>
Hereinafter, the seal structure of the embodiment used for the engine 2 will be described. FIG. 4 is a schematic view of the first piston member 24 and the seal structure as viewed in the axial direction. The first piston member 24 has an annular facing surface facing the second piston member 28 inside the combustion chambers A to D in the radial direction.

The seal structure includes a mating surface seal 40. The mating surface seal 40 has an annular shape. The mating surface seal 40 has a circular shape. The mating surface seal 40 is arranged concentrically with the first piston member 24 and the second piston member 28. The mating surface seal 40 is in contact with both the first rotating body 24a and the second rotating body 28a. The mating surface seal 40 is arranged inside the combustion chambers A to D in the radial direction, and seals the inner peripheral portions of the combustion chambers A to D. The mating surface seal 40 suppresses gas leakage from the combustion chambers A to D to the inner peripheral side.

The seal structure includes an outer peripheral seal 96. The outer peripheral seal 96 has an annular shape. The outer peripheral seal 96 has a circular shape. The outer peripheral seal 96 is arranged concentrically with the first piston member 24 and the second piston member 28. The outer peripheral seal 96 is in contact with both the first rotating body 24a and the second rotating body 28a. The outer peripheral seal 96 is arranged outside the combustion chambers A to D in the radial direction, and seals the outer peripheral portions of the combustion chambers A to D. The outer peripheral seal 96 suppresses gas leakage from the combustion chambers A to D to the outer peripheral side.

The seal structure includes an oil seal 70. The oil seal 70 is arranged inside the combustion chambers A to D in the radial direction. The oil seal 70 is arranged inside the mating surface seal 40 in the radial direction. The oil seal 70 seals the lubricating oil that lubricates the first piston member 24 and the second piston member 28, and suppresses the leakage of the lubricating oil into the combustion chambers A to D.

The oil seal 70 has an annular shape. The oil seal 70 has a circular shape. The center 70C of the oil seal 70 is eccentric with respect to the rotation center axis AX of the first piston member 24 and the second piston member 28. The oil seal 70 is arranged so that the center 70C is offset from the rotation center axis AX.

FIG. 5 is a schematic cross-sectional view showing a first example of a contact state between the first piston member 24 and the second piston member 28 and the oil seal 70. A hollow space S is formed between the first piston member 24 and the second piston member 28. The oil seal 70 is arranged in the space S, and is arranged between the first piston member 24 and the second piston member 28. The oil seal 70 is in surface contact with both the first piston member 24 and the second piston member 28. A space S is formed between the flat surface of the first piston member 24 and the flat surface of the second piston member 28, and the oil seal 70 is sandwiched between both flat surfaces.

The oil seal 70 shown in FIG. 5 has a rectangular cross section. The oil seal 70 is not limited to a rectangular shape and may have an arbitrary cross-sectional shape.

FIG. 6 is a schematic cross-sectional view showing a second example of the contact state between the first piston member 24 and the second piston member 28 and the oil seal 70. Unlike the example shown in FIG. 5, the second piston member 28 shown in FIG. 6 has a groove 28G formed on the surface facing the space S. The groove 28G is open toward the first piston member 24. A part of the oil seal 70 is housed in the groove 28G. The oil seal 70 is in surface contact with the second piston member 28 on the bottom surface and the side surface of the groove 28G.

The oil seal 70 may be formed in a C ring having a notch at one position in the circumferential direction. The oil seal 70 may generate a radial outward tension to come into contact with the radial outer side surface of the groove 28G, or may generate a radial inward tension to generate the diameter of the groove 28G. It may touch the side surface inside the direction. The oil seal 70 may be configured to have a spring to generate tension outward or inward in the radial direction so as to ensure contact with the bottom surface and / or side surface of the groove 28G.

<Action and effect>
In the seal structure of the embodiment described above, as shown in FIG. 4, the center 70C of the circular oil seal 70 arranged radially inside the combustion chambers A to D is the first piston member 24 and the second piston member 24 and the second. The piston member 28 is eccentric with respect to the rotation center axis AX.

During the operation of the engine 2, the first piston member 24 and the second piston member 28 rotate alternately. At this time, the oil seal 70 rotates in an eccentric state. For example, when the oil seal 70 rotates in the clockwise direction in the drawing from the arrangement shown in FIG. 4, the center 70C of the oil seal 70 moves in a circular locus about the rotation center axis AX. The center 70C of the oil seal 70 moves in this order from the position on the left side of the rotation center axis AX shown in FIG. 4, the position above the rotation center axis AX, the position on the right side of the rotation center axis AX, and the position below the rotation center axis AX. Then, it returns to the position on the left side of the rotation center axis AX again.

Since the oil seal 70 rotates in an eccentric state in this way, the area where the oil seal 70 slides with respect to either the first piston member 24 or the second piston member 28 is increased. The locus of the oil seal 70 has a radial width larger than the radial dimension of the oil seal 70 itself, and the oil seal 70 is slid on average within the width. The area of contact with the oil seal 70 when sliding is increased, and the same portion is prevented from repeatedly sliding. Therefore, the amount of wear on the contact surface of the oil seal 70 can be reduced without impairing the sealing property.

The oil seal 70 arranged eccentrically can generate an oil film coating effect. For example, if the center 70C of the oil seal 70 is on the left side of the rotation center axis AX shown in FIG. 4, and the lubricating oil is supplied to the region radially outside the oil seal 70 on the right side of the rotation center axis AX, Next, when the oil seal 70 moves so that the center 70C is on the right side of the rotation center axis AX, the lubricating oil can be distributed throughout. Therefore, the seizure resistance of the oil seal 70 can be improved, and the required amount of lubricating oil can be reduced.

Compared with the gas seal (matching surface seal 40) for ensuring the airtightness of the combustion chambers A to D, the oil seal 70 that seals the lubricating oil has a larger force than the first rotating body 24a and the second rotating body 24a. It is pressed against the body 28a. Wear is more likely to occur on the contact surface of the oil seal 70. Therefore, by applying the configuration of the present embodiment in which the center 70C is arranged so as to be offset from the rotation center axis AX to the oil seal 70, it becomes possible to reduce wear more effectively and improve the reliability of the engine 2. be able to.

In the case of the configuration shown in FIG. 5 in which the oil seal 70 is sandwiched between the flat surfaces without the groove 28G shown in FIG. 6, it is difficult to manage the gap size of the space S. Therefore, the pressing load of the oil seal 70 on the first rotating body 24a and the second rotating body 28a becomes large, and wear is more likely to occur. Therefore, by applying the idea of the present embodiment in which the center 70C of the oil seal 70 is displaced from the rotation center axis AX to the configuration shown in FIG. 5, wear can be reduced more effectively.

In the description so far, an example of offsetting the center 70C of the oil seal 70 from the rotation center axis AX has been described. The idea of the embodiment in which the center is shifted from the rotation center axis AX may be applied to the gas seal (matching surface seal 40).

[Second Embodiment]
FIG. 7 is a schematic view of the first piston member 24 and the seal structure according to the second embodiment as viewed in the axial direction. The seal structure shown in FIG. 7 includes a mating surface seal 40 and an outer peripheral seal 96 similar to those in the first embodiment. The seal structure includes an oil seal 70. Unlike the first embodiment, the oil seal 70 has a non-circular shape. The oil seal 70 has an elliptical shape. The center 70C of the oil seal 70 coincides with the rotation center axis AX of the first piston member 24 and the second piston member 28.

With such a configuration, it is possible to increase the contact area when the oil seal 70 is slid, as in the first embodiment. Therefore, the effect of reducing the wear of the contact surface of the oil seal 70 and the effect of applying an oil film can be similarly obtained.

The oil seal 70 is not limited to the elliptical shape shown in FIG. 7. If the oil seal 70 has a non-circular shape, the effect of increasing the contact area when the oil seal 70 slides can be similarly obtained. For example, the oil seal 70 may be formed into an oval shape or the like. The idea of the second embodiment in which the seal structure is made non-circular may be applied to the gas seal (matching surface seal 40).

Although the embodiments have been described above, it should be considered that the embodiments disclosed this time are exemplary in all respects and are not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

2 engine, 4 housing, 16 1st output shaft, 18 2nd output shaft, 24 1st piston member, 24a 1st rotating body, 24b 1st wall surface member, 24s 1st rotating shaft part, 28 2nd piston member, 28G Groove, 28a 2nd rotating body, 28b 2nd wall member, 28s 2nd rotating shaft part, 40 mating surface seal, 70 oil seal, 70C center, 96 outer circumference seal, A, B, C, D combustion chamber, AX rotation center Axis, S space.

Claims (4)

It is a seal structure used for internal combustion engines.
The internal combustion engine includes a housing, a first piston member rotatably supported in the housing about a rotation center axis, and a second piston rotatably supported in the housing about the rotation center axis. A combustion chamber is formed by the housing, the first piston member, and the second piston member, including the member, and the first piston member is located inside the combustion chamber in the radial direction. It has an annular facing surface facing the second piston member and has an annular facing surface.
The seal structure includes a circular seal member arranged radially inside the combustion chamber.
A seal structure for an internal combustion engine in which the center of the seal member is eccentric with respect to the rotation center axis. The seal structure according to claim 1, wherein the seal member is an oil seal that seals lubricating oil. A space is formed between the flat surface of the first piston member and the flat surface of the second piston member.
The seal structure according to claim 1 or 2, wherein the seal member is arranged in the space and is sandwiched between both flat surfaces. A space is formed between the first piston member and the second piston member.
The second piston member has a groove formed on the surface facing the space so as to open toward the first piston member.
The seal structure according to claim 1 or 2, wherein a part of the seal member is housed in the groove.