JPH0587239U - Sound insulation structure of engine case - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sound insulation structure for an engine case capable of always obtaining a sufficient sound insulation effect in response to various engine case shapes by increasing the occupied area of the hollow double cover of the cover member. In an engine case accommodating a clutch, a generator, etc., a cover member 1 of the engine case is divided into a plurality of pieces in a shape along an outer side surface thereof, and elastic members 14, 34 are provided on the outer side surface for each divided cover portion. , 44 via lid members 15, 35,
A sound insulation structure for an engine case, in which 45 is mounted and a plurality of hollow layers divided by the lid members 15, 35, 45 are formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sound insulation structure for an engine case that houses a clutch, a generator, and the like inside an internal combustion engine.

[0002]

[Prior art]

 Some engine cases, such as motorcycles, house a crankshaft, clutch, generator, timing gear, flywheel, etc., but the engine case cover is relatively thick for the purpose of weight reduction. Since it is made of a thin material, it is not sufficient to block the operating noise generated by the various mechanisms described above, and the engine case cover member resonates with the vibration and operating noise of these mechanisms to generate noise. There was also a reason to make it.

Therefore, as a sound insulation structure that has been conventionally adopted, there is an example in which a steel plate is attached to the inside of a cover member via a floating rubber with a floating bolt to form a double wall for sound insulation and to prevent resonance. Further, an example in which an outer cover is attached only to the drum-shaped portion of the cover member via an elastic member to form a hollow layer so as to have effects of sound insulation and resonance prevention (Japanese Patent Laid-Open No. 57-8318 and Japanese Utility Model Publication No. 59-3154). No.)

[0004]

[Problems to be solved]

FIG. 5 shows the result of an experiment conducted to determine the effect of the double cover. In FIG. 5, the horizontal axis represents the area ratio S ₁ / So of the area S ₁ of the double cover portion to the total area So of the cover member, and the vertical axis represents the reduced energy ratio A. is there.

The reduction energy ratio A will be described here. Regarding the engine used for the measurement, first, the total noise No generated by the engine cover that does not have the hollow double cover structure is measured, and then the part that is considered to be the double cover is masked so that no sound is generated from the cover part. In this state, the total sound N ₁ is measured, and the difference No −N ₁ between them is calculated to calculate the sound S _OE generated from the cover portion.

Next, the total generated sound N ₂ of the engine having a hollow double cover structure was measured, and the difference S0-N ₂ from No was taken, and the sound S reduced by the hollow double cover structure was reduced. Calculate _1E .

The reduction energy ratio A is obtained from the above S _OE and S _1E by the following equation. log ₁₀ A = (S _1E −S _OE ) / 10 The reduced energy ratio A is the ratio of the reduced energy amount due to the hollow double-cover structure to the overall energy amount reduced by masking. This is shown in percentage on the vertical axis in FIG.

As S _1E shows a value closer to S _OE , the reduction energy ratio A approaches 100%, indicating that the sound insulation effect is excellent. In Fig. 5, ☆ and ★ are the results of measurement and analysis of a hollow double cover structure (corresponding to a structure in which only the drum part has a double cover) with an area ratio S ₁ / So of about 30%. The shift state is the second case, and the star is the third case. The reduced energy ratio A shows a little over 50% in the second state, but it is less than 25% in the third state.

On the other hand, ○ and ● are measured and analyzed for a hollow double cover structure in which the area ratio S ₁ / So exceeds 60%, and ○ is the second state and ● is the third state. In all cases, the reduced energy ratio A is 100%, and sufficient sound insulation effect is obtained. That is, it can be seen that a sufficient sound insulation effect cannot be obtained unless the area ratio S ₁ / So is 60% or more.

However, since the inside of the cover member is a portion where ribs are intricately intersected with each other, the steel plate provided inside the conventional cover member ensures the above-mentioned area ratio of 60% required for sound reduction. Difficult to do. Also, the outer cover attached via the elastic member only to the drum-shaped portion of the cover member is necessary for noise reduction if the engine case has a simple shape and the drum-shaped portion occupies most of the cover member. It is possible to secure the area ratio of 60%, but if the shape of the engine case becomes complicated, it becomes difficult to secure 60%, and a sufficient sound insulation effect cannot be obtained.

The present invention has been made in view of the above point, and an object of the present invention is to provide a sound insulation structure of an engine case having a large sound reduction effect.

[0012]

[Means and Actions for Solving the Problems]

 In order to achieve the above object, the present invention, in an engine case that accommodates a clutch, a generator, etc., divides a cover member of the engine case into a plurality of pieces in a shape along the outer side surface thereof, A lid member was attached to the outer surface via an elastic member to form a sound insulation structure for the engine case in which a plurality of hollow layers divided by the lid member were formed.

Even if the engine case has a complicated shape, since the cover member is divided into a plurality of parts and a hollow double cover is formed for each divided cover part, the area ratio required to effectively reduce sound is 60% can be easily secured.

[0014]

【Example】

 Hereinafter, a crankcase of a motorcycle according to an embodiment of the present invention shown in FIGS. 1 to 3 will be described.

FIG. 1 is an exploded perspective view of a side cover 1 of the crankcase. The side cover 1 is divided into three blocks by laterally projecting peripheral walls 2, 3, 4 whose outer surfaces are closed along the shape.

The peripheral wall 2 is located on the front side to form the largest block having a perfect circular shape, and the peripheral wall 3 located behind the peripheral wall 2 is an incomplete circular block partially crushed by the peripheral wall 2. The peripheral wall 4 forms an elongated block from below the peripheral wall 3 to the rear. Each block has a different shape and size, but a hollow double cover is constructed under the same structure.

Explaining the block surrounded by the peripheral wall 2, the inner side of the peripheral wall 2 has a shape in which an inner cover 12 serving as an inner wall is stretched through an annular step portion 11. The inner cover 12 has three cylindrical shapes. The female screw protrusion 13 is provided at a predetermined position. The annular floating rubber 14 fitted to the inner periphery of the peripheral wall 2 has an annular outer peripheral edge portion 14a protruding laterally, three bulging portions 14b inside, and each bulging portion 14b. Has a circular hole 14c corresponding to the female screw projection 13 of the inner cover 12.

A disk-shaped outer cover 15 is fitted inside the outer peripheral edge portion 14 a of the floating rubber 14. The outer cover 15 is a steel plate or an aluminum plate, and is provided with stepped circular holes 15a at three locations corresponding to the circular holes 14c. The circular hole 15a has a cylindrical shape and a flange at the end. The floating rubber bush 16 having the above is fitted. The cylindrical portion of the floating rubber bush 16 is fitted into the small diameter portion of the circular hole 15a of the outer cover 15, and the flange abuts against the step portion and is sunk in the large diameter portion of the circular hole 15a.

A washer 17 is applied to the flange end surface of the floating rubber bushing 16 and a stepped bolt 18 is screwed therethrough. A cap 19 for covering the head of the stepped bolt 18 from the outside is fitted into the circular hole 15a of the outer cover 15.

Explaining the above-mentioned assembling process again step by step, first, the floating rubber 14 is fitted by contacting the step portion 11 inside the peripheral wall 2, and the circular hole 14c of the bulge portion 14b is aligned with the female screw protrusion 13. Then, when the outer cover 15 is fitted inside the outer peripheral edge portion 14a of the floating rubber 14 with the circular holes 14c and 15a aligned with each other, the end surface of the peripheral wall 2 and the end surface of the outer peripheral edge portion 14a of the floating rubber 14 and the outer cover 15 are fitted. The outer surface of and are all on the same plane.

When the floating rubber bush 16 is fitted into the stepped circular hole 15 a of the outer cover 15, the tip of the floating rubber bush 16 abuts on the bulging portion 14 b of the floating rubber 14 and the flange of the floating rubber bush 16 A washer 17 is applied to the end face and a stepped bolt 18 is screwed in (see Fig. 3). The stepped bolt 18 has a large-diameter base end that penetrates the washer 17 and the floating rubber bush 16, and the tip screw portion is screwed onto the female screw protrusion 13.

Therefore, the outer cover 15 is screwed to the side cover 1 via the floating rubber 14 and the floating rubber bushing 16, so that the outer cover 15 and the inner cover 12 are provided with the stepped portion 11 and the floating rubber 14. The hollow layer 20 having a width corresponding to the thickness is formed to form a hollow double cover.

The cap 19 fitted in the concave portion of the circular hole 15a of the outer cover 15 has a shape in which the center of a circular plate having the same diameter as the circular hole 15a bulges outward, and locking pieces 19a are provided at three positions on the peripheral edge. It is projectingly provided on the inner side, and when it is fitted into the concave portion of the circular hole 15a, the locking piece 19a is inserted between the outer peripheral surface of the flange of the floating rubber bush 16 and the inner peripheral surface of the circular hole 15a to be clamped. The head of bolt 18 is covered. Therefore, the appearance of the side cover after being assembled as shown in FIG. 2 is not damaged. The block surrounded by the peripheral wall 2 is configured as described above.

Similarly, the block surrounded by the peripheral wall 3 also constitutes the same hollow double cover structure. That is, a step portion 31 is formed on the inner periphery of the peripheral wall 3, and an inner cover 32 having two female screw protrusions 33 projecting from the inner portion is stretched on the inner side of the step portion 31, and a partial recess corresponding to the inner periphery of the peripheral wall 3 is formed. The incomplete circular annular floating rubber 34 is fitted, the circular hole 34c of the bulging portion 34b of the floating rubber 34 abuts on the female screw projection 33, and then the outer cover 35 is attached to the outer peripheral edge portion 34a of the floating rubber 34. Although not shown, a floating rubber bush is fitted into a stepped circular hole 35a of the outer cover 35, a washer is applied, and a cap 36 is screwed with a stepped bolt.

Similarly, in the block surrounded by the peripheral wall 4, the outer cover 45 is attached via the elongated annular floating grabber 44 having the same shape as the peripheral wall 4 and the floating rubber bush, and the cap 46 is put on the bolt.

On the outer side surface of the side cover 1, the three blocks divided by the peripheral walls 2, 3 and 4 as described above constitute a hollow double cover under the same structure. Therefore, the area ratio of the double cover portion to the total area of the side cover 1 greatly exceeds 60%, and a sufficient sound insulation effect can be obtained.

Even if the crankcase and the side cover have a complicated shape, the area ratio is always kept at 60% or more by dividing the block into several blocks according to the shape to form a hollow double cover. It is possible to expect a great sound insulation effect.

Although the inner cover and the outer cover are flat plates in the above embodiments, even if the outer surface of the inner cover 50 has a step as shown in FIG. By bending the outer cover 51 to form a step, the outer cover 51 can be attached in parallel to the outer side of the inner cover 50 via the floating rubber 52 to form the hollow layer 53, which has a wide range of application. ..

Therefore, the hollow double cover structure can be applied not only to the crankcase but also to the cylinder outer wall, the cylinder head outer wall, and the like. On the other hand, if the outer cover is unified so that it can be used in common for many models, mass production is possible at low cost.

[0030]

[Effect of the device]

 According to the present invention, the cover member is divided into a plurality of parts and a hollow double cover is formed for each of the divided cover parts. Therefore, even if the engine case has a complicated shape, it is necessary to effectively reduce the noise. The area of the double cover part can be easily secured, and a sufficient sound insulation effect can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a side cover portion of an engine crankcase of a motorcycle according to an embodiment of the present invention.

FIG. 2 is a perspective view of a side cover showing the assembled state.

FIG. 3 is a sectional view of the same portion.

FIG. 4 is a sectional view of a side cover portion of another embodiment.

FIG. 5 is a diagram showing a sound reduction energy ratio with respect to an area ratio.

[Explanation of symbols]

1 ... Side cover, 2, 3, 4 ... Peripheral wall, 11 ... Step, 12 ...
Inner cover, 13 ... Female thread protrusion, 14 ... Floating rubber, 15 ... Outer cover, 16 ... Floating rubber bush, 17 ... Washer, 18 ... Stepped bolt, 19 ... Cap, 20 ... Hollow layer, 31 ... Step section, 32 ... Inner cover, 33
… Female thread protrusion, 34… Floating rubber, 35… Outer cover, 36… Cap, 41… Step, 44… Floating rubber, 45… Outer cover, 46… Cap, 50… Inner cover, 51… Outer cover, 52… Flow Tewing rubber, 53… Hollow layer.

Claims (1)

[Scope of utility model registration request] 1. An engine case for accommodating a clutch, a generator, etc., wherein a cover member of the engine case is divided into a plurality of pieces in a shape along an outer side surface thereof, and an elastic member is provided on the outer side surface for each divided cover part. A sound insulation structure for an engine case, characterized in that a lid member is attached, and a plurality of hollow layers divided by the lid member are formed.