JP3216010B2 - Engine with flywheel housing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine with a flywheel housing.

[0002]

2. Description of the Related Art FIG. 2 shows a prior art of an engine having a flywheel housing. As shown in FIG. 2A, a bowl-shaped flywheel housing 102 is attached to a crankcase 101, and a housing end wall 103 of the flywheel housing 102 is connected to a case wall 105 of the crankcase 101. The crankshaft 106 penetrates through the case wall 105 and the housing end wall 103, and the flywheel 107 is fixed to the crankshaft 106.
Is housed in the flywheel housing 102, an end facing space 109 is provided between the housing end wall 103 and the flywheel end face 108 facing each other, and between the housing peripheral wall 110 and the flywheel peripheral face 111 facing each other. A peripheral facing space 112 is provided.

In this type of engine, the crankshaft 106
When the rotational attitude of the flywheel 107 is deviated due to a rubbing motion or the like, the air density in the end face facing space 109 is made nonuniform and a compression wave is generated.
From 09, the noise propagates to the peripheral surface facing space 112, and is emitted as noise outside the flywheel housing 102.

In this prior art, as shown in FIG. 2C, a crankshaft 1 is attached to an outer edge of a housing end wall 103.
A continuous circular sound insulation wall 125 is arranged along a virtual circle centered at 06, and as shown in FIG.
An aperture space 127 is formed between the protruding end surface 126 of the 25 and the flywheel end surface 108. And the aperture space 1
The compression wave generated closer to the center than 27 is prevented from propagating to the outside by the throttle gap 127.

[0005]

However, the above-mentioned prior art has the following problems. In the above prior art, as shown in FIG. 1 (C), a continuous circular sound insulation wall 125 is arranged on the outer edge of the housing end wall 103 along an imaginary circle centered on the crankshaft 106. As shown in (B), since the aperture space 127 is formed between the projecting end surface 126 of the sound insulating wall 125 and the flywheel end surface 108, the sound insulating wall 12
Ventilation in the end facing space 109 surrounded by 5 is hardly performed. For this reason, compared with immediately after the engine start, during the normal operation after a predetermined time has elapsed from the engine start, the heat shield wall 1
The temperature of the air stagnating in the end face facing space 109 surrounded by 25 significantly increases, and the thermal expansion amount of the sound insulating wall 125 increases during normal operation. As a result, the dimensional difference between the throttle gap 127 immediately after the start of the engine and during normal operation increases, and the difference between the soundproofing performance immediately after the engine starts and during normal operation increases.

[0006] Each invention relates to an engine with a flywheel housing, and an object of the first invention is to provide an engine capable of reducing a difference in soundproof performance depending on operating conditions of the engine. A second object of the present invention is to provide, in addition to the first object, a device capable of enhancing a soundproofing function. A third object of the present invention is to provide a flywheel housing capable of reducing the weight, in addition to the objects of the first or second invention. A fourth object of the present invention is to provide, in addition to any one of the first to third inventions, a device capable of enhancing a soundproofing function.

[0007]

[Means for Solving the Problems]

(First Invention) In a first invention, as shown in FIG. 1A, a bowl-shaped flywheel housing 2 is attached to a crankcase 1 and a housing end wall 3 of the flywheel housing 2 is attached to a case of the crankcase 1. A crankshaft 6 is passed through the case wall 5 and the housing end wall 3 along the wall 5, a flywheel 7 is fixed to the crankshaft 6, and the flywheel 7 is housed in the flywheel housing 2.
The housing end wall 3 and the flywheel end face 8 facing each other
An engine with a flywheel housing, in which an end surface facing space 9 is provided between the housing and the peripheral surface facing space 12 between the housing peripheral wall 10 and the flywheel peripheral surface 11 facing each other, It is characterized by.

That is, as shown in FIG. 1 (C), a plurality of sound insulation walls 13 are arranged on the housing end wall 3 along the circumferential direction thereof, and as shown in FIGS. 1 (A) and 1 (B), each sound insulation wall 13 is provided. 13
Is formed by projecting a portion from the radially intermediate portion to the outer edge of the housing end wall 3 from the housing end wall 3 toward the flywheel end surface 8, so that the projection end surface 14 of each sound insulating wall 13 and the flywheel end surface 8 A narrow gap 15 is formed therebetween, and a ventilation gap 16 is provided between adjacent sound insulating walls 13 as shown in FIG.

(Second Invention) In a second invention, as shown in FIG. 1 (C), in the first invention, the reflecting surface 18 of the sound insulating wall 13 facing the center portion of the space 9 facing the end face is changed to the crankshaft 6. Is formed in the shape of an arc having the center as the center.

(Third invention) A third invention is shown in FIG.
As shown in FIG. 2B, in the first or second invention, the sound insulation wall 13 is formed by forming a part of the housing end wall 3 and a part of the housing peripheral wall 10 into a mountain-fold shape that enters the flywheel housing 2. Is formed.

(Fourth Invention) As shown in FIG. 1 (C), a fourth invention provides a method according to any one of the first to third inventions.
As viewed in a direction parallel to the direction in which the crankshaft 6 is laid, the crank arm 17 connected to the piston of the combustion chamber during combustion.
However, at the start of combustion, it is directed to the direction of the sound insulation wall 13.

[0012]

Function and Effect of the Invention

(First invention) The first invention has the following effects. In the first invention, when the rotational attitude of the flywheel 7 is deviated due to the slewing motion of the crankshaft 6 or the like, the end face facing space 9
The density of the air inside the air becomes uneven, resulting in compression waves. The compression wave generated near the center of the end face facing space 9 collides with the sound insulating wall 13, rebounds toward the center, and interferes with the subsequent compression wave to reduce the sound. The compressional waves leaking from the center of the end face facing space 9 into the ventilation gap 16 and the compressional waves generated in the ventilation gap 16 collide with the housing peripheral wall 10 and are rebounded toward the center, and the subsequent compressional waves are generated. Interference is reduced.

Further, while the gap size of the space near the center of the space 9 facing the end face and the ventilation gap 16 is relatively long,
5 has a relatively short gap size, so that the frequency characteristics of the compressional waves generated from the respective portions differ. Therefore, by devising these gap dimensions, area distribution and arrangement, the ratio and frequency characteristics of compression waves generated from each part are adjusted, and compression waves in the unpleasant frequency region due to these interferences are efficiently reduced. Can sound.

In the first aspect of the present invention, as shown in FIG. 1C, when air in the end face facing space 9 accumulates, the air passes through the ventilation gap 16 and the peripheral face facing space 12 by convection in order. Ventilated. For this reason, even during the normal operation after a predetermined time has elapsed from the start of the engine, the end face facing space 9
The temperature of the air in the inside does not become so high as immediately after the start of the engine, and the amount of thermal expansion of the sound insulating wall 13 during normal operation is suppressed to a small value. Thereby, the dimensional difference between the throttle gap 15 immediately after the start of the engine and during normal operation is reduced, and the difference in the amount of compression wave transmitted through the throttle gap 15 is reduced. The difference is smaller.

(Second Invention) The second invention has the following functions and effects in addition to the functions and effects of the first invention. In the second invention, as shown in FIG. 1 (C), since the reflection surface 18 of the sound insulating wall 13 is formed in an arc shape, most of the compression waves which collided with them are bounced back to the inside thereof, and are reduced by interference. The sound is made more effective.

(Third invention) The third invention has the following functions and effects in addition to the functions and effects of the first invention or the second invention. In the third invention, as shown in FIGS. 1A and 1B, a part of the housing end wall 3 and a part of the housing peripheral wall 10 are formed into a mountain-folded shape that enters the flywheel housing 2. Since the sound insulation wall 13 is formed, the housing end wall 1 is formed.
Flywheel housing 2
Can be reduced in weight.

(Fourth Invention) The fourth invention has the following effects in addition to the effects of any of the first to third inventions. As shown in FIG. 1C, the crank arm 17 connected to the piston of the combustion chamber during combustion is directed toward the sound insulating wall 13 at the start of combustion, so that the torsion of the crankshaft 6 at the start of combustion. Since the large displacement of the flywheel 7 caused by this occurs at the position of the throttle gap 15 where the amount of air is small, the amount of compression waves can be reduced and the soundproof performance can be improved.

[0018]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an embodiment of the present invention. In this embodiment, a vertical engine with a flywheel housing is used.

The configuration of this engine is as follows. As shown in FIG. 1 (A), a bowl-shaped flywheel housing 2 is attached to a crankcase 1 and a housing end wall 3 of the flywheel housing 2 is aligned with a case wall 5 of the crankcase 1. The flywheel 7 is fixed to the crankshaft 6, the flywheel 7 is accommodated in the flywheel housing 2, and the housing end wall 3 and the flywheel An end face facing space 9 is provided between the end face 8 and a peripheral face facing space 12 is provided between a housing peripheral wall 10 and a flywheel peripheral face 11 which face each other.

According to such a configuration, when the rotational attitude of the flywheel 7 is deviated due to the rubbing motion of the crankshaft 6 or the like, the air density in the end face facing space 9 becomes non-uniform, resulting in compression waves. This propagates from the end face facing space 9 to the peripheral face facing space 12 and is emitted outside the flywheel housing 2 as noise.

To fix the flywheel housing 2 to the crankcase 1, the housing end wall 3 is fixed to the crankcase 1.
This is performed by fixing the case wall 5 with a fixing bolt 29. The flywheel 7 is fixed to the crankshaft 6 by attaching the flywheel 7 to the crankshaft 6 with mounting bolts 30.

In this embodiment, as shown in FIG. 1 (C), a plurality of sound insulation walls 13 are arranged on the housing end wall 3 along the circumferential direction thereof, and as shown in FIGS. 1 (A) and 1 (B). Each sound insulation wall 13 is formed by projecting a portion from the radially intermediate portion to the outer edge of the housing end wall 3 toward the flywheel end face 8 from the housing end wall 3, and the projecting end face 14 of each sound insulation wall 13 and the flywheel are formed. An aperture gap 15 is formed between the end face 8 and the air gap 16 between the adjacent sound insulation walls 13 as shown in FIG.

According to such a configuration, the end face facing space 9
The compression wave generated near the center of the target collides with the sound insulation wall 13 and rebounds toward the center, and interferes with the subsequent compression wave to reduce the sound. The compressional waves leaking from the center of the end face facing space 9 into the ventilation gap 16 and the compressional waves generated in the ventilation gap 16 collide with the housing peripheral wall 10 and are rebounded toward the center, and the subsequent compressional waves are generated. Interference is reduced.

Further, while the gap size of the space near the center of the end face facing space 9 and the ventilation gap 16 is relatively long,
5 has a relatively short gap size, so that the frequency characteristics of the compressional waves generated from the respective portions differ. Therefore, by devising these gap dimensions, area distribution and arrangement, the ratio and frequency characteristics of compression waves generated from each part are adjusted, and compression waves in the unpleasant frequency region due to these interferences are efficiently reduced. Can sound.

Then, as shown in FIG. 1C, the air in the space 9 facing the end surface is ventilated through the ventilation gap 16 and the space 12 facing the peripheral surface in this order. Therefore, even during a normal operation after a predetermined time has elapsed from the start of the engine, the temperature of the air in the end face facing space 9 does not become so high as compared with immediately after the start of the engine, and the thermal expansion amount of the sound insulating wall 13 during the normal operation. Can be kept small. Thereby, the dimensional difference between the throttle gap 15 immediately after the start of the engine and during normal operation is reduced, and the difference in the amount of compression wave transmitted through the throttle gap 15 is reduced. The difference is smaller.

The sound insulating wall 13 has the crankshaft 6 interposed therebetween.
One each, two in total, are formed on opposite sides. When viewed in a direction parallel to the direction in which the crankshaft 6 is laid, each sound insulating wall 13 is formed in a fan shape with a central angle of 90 ° about the crankshaft 6. An annular starting ring gear 23 is fitted to the flywheel 7, and the projecting end faces 14
A throttle gap is also formed between the end ring 24 and the end face 24 of the ring gear 23 for starting. A starter motor 31 is fixed to the housing end wall 3, and a pinion gear 32 attached to the starter motor 31 is engaged with the starting ring gear 23.

In this embodiment, as shown in FIG. 1 (C), the sound insulating wall 1 facing a portion near the center of the space 9 facing the end surface.
The third reflecting surface 18 is formed in an arc shape centering on the crankshaft 6. For this reason, many of the compression waves which collided with these waves are certainly bounced inward, and sound reduction by interference is more effectively performed.

In this embodiment, as shown in FIGS. 1 (A) and 1 (B), a part of the housing end wall 3 and a part of the housing peripheral wall 10 are formed into a mountain-folded shape which enters the flywheel housing 2. By doing so, the sound insulation wall 13 is formed. Therefore, the weight of the flywheel housing 2 can be reduced as compared with the case where the housing is overlaid on the housing end wall 10.

In this embodiment, as shown in FIG. 1 (C), the crank arm 1 connected to the piston of the combustion chamber during combustion is viewed in a direction parallel to the direction in which the crank shaft 6 is erected.
7 is directed toward the sound insulation wall 13 at the start of combustion. For this reason, since the large deflection of the flywheel 7 caused by the twist of the crankshaft 6 at the start of combustion occurs at the position of the throttle gap 15 with a small amount of air, the amount of compressional waves can be reduced and the soundproof performance can be improved. .

[Brief description of the drawings]

FIG. 1 is a view for explaining an engine with a flywheel housing according to an embodiment of the present invention. FIG. 1 (A) is a longitudinal sectional view of a main part, and FIG. 1 (B) is a view of a portion B in FIG. 1 (A). FIG. 1C is an enlarged view of FIG. 1A along the line CC.

FIG. 2 is a view for explaining an engine with a flywheel housing according to the prior art, and FIG. 2 (A) is a longitudinal sectional view of a main part,
FIG. 2B is an enlarged view of a portion B in FIG. 2A, and FIG.
FIG. 3 is a sectional view taken along line CC of FIG.

[Explanation of symbols]

1 ... crankcase, 2 ... flywheel housing, 3
... Housing end wall, 5 ... Case wall, 6 ... Crankshaft, 7
... Fly wheel, 8 ... Fly wheel end wall, 9 ... End face opposed space, 10 ... Housing peripheral wall, 11 ... Fly wheel peripheral face, 12 ... Peripheral face opposed space, 13 ... Sound insulation wall, 14 ... Protruded end face, 15 ... Drawing gap, 16 ... ventilation gap, 17 ... crank arm, 18 ... reflection surface.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02B 77/00 F02B 61/06 F02F 7/00 F15F 15/30

Claims (4)

(57) [Claims] 1. A bowl-shaped flywheel housing (2) is mounted on a crankcase (1), and a housing end wall (3) of the flywheel housing (2) is attached to a case wall (5) of the crankcase (1). A crankshaft (6) is passed through the case wall (5) and the housing end wall (3), and a flywheel (7) is fixed to the crankshaft (6).
(7) is housed in a flywheel housing (2), and an end face opposing space (9) is provided between a housing end wall (3) and a flywheel end face (8) opposing each other, and housing peripheral walls opposing each other. An engine with a flywheel housing provided with a peripheral surface facing space (12) between a flywheel peripheral surface (11) and a flywheel peripheral surface (11), wherein a plurality of sound insulation walls are provided on a housing end wall (3) along a circumferential direction thereof.
(13), and each sound insulation wall (13) is a housing end wall.
A portion extending from the radially intermediate portion to the outer edge portion of (3) is formed by projecting from the housing end wall (3) toward the flywheel end surface (8), and the projecting end surface (14) of each sound insulation wall (13) is formed.
Characterized in that a throttle gap (15) is formed between the end face (8) and the flywheel end face (8), and a ventilation gap (16) is provided between adjacent sound insulation walls (13). Engine with housing. 2. The engine with a flywheel housing according to claim 1, wherein the reflection surface (18) of the sound insulation wall (13) facing the center portion of the space (9) facing the end face is centered on the crankshaft (6). An engine with a flywheel housing formed in an arc shape. 3. An engine with a flywheel housing according to claim 1, wherein a part of the housing end wall (3) and a part of the housing peripheral wall (10) are provided in the flywheel housing (2). An engine with a flywheel housing, wherein a sound insulation wall (13) is formed by making a mountain-folding shape to penetrate. 4. The engine with a flywheel housing according to claim 1, wherein the engine is connected to a piston of a combustion chamber during combustion, as viewed in a direction parallel to the direction in which the crankshaft is erected. Working Crank Arm (17)
Characterized in that the engine faces the direction of the sound insulation wall (13) at the start of combustion.