JP2008202482A - Cooling fan cover for forced air-cooled engine and vibration isolation - sound suppression support method for cooling fan cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration isolation and sound suppression support method, and a structure, for a cooling fan cover forming a casing for a fan supplying cooling air to a forced air-cooled engine. <P>SOLUTION: In the cooling fan cover for the forced air-cooled engine having a structure directly fixing a plurality of fixing leg parts provided on a circumference edge on a cylinder block by bolts, a vibrating main components of the fan cover circumference edge is installed, putting a soft vibration isolation material between a surface of a cylinder block and it, and with the soft vibration isolation material pressed against the surface of the cylinder block to which the soft vibration isolation material faces. At that time, the soft vibration isolation material is formed into a shape having thick C-shape section. A bottom surface is squeezed and fixed by a bottom surface of the fan cover and a surface of the cylinder block. Consequently, a resonance zone of the fan cover is shifted above a normal operation area of the engine, and the fan cover is joined with pressing-fitting a top end of the C-shape vibration isolation material into a slit provided on an approximately flat surface part and a flat surface part of the fan cover. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an anti-vibration and sound-damping support method and structure for a cooling fan cover that forms a casing of a fan that supplies cooling air to a forced air cooling engine.

  In a forced air cooling engine that includes a cooling fan at one end of a horizontally disposed crankshaft and that cools the cylinder by applying cold air from the fan to a cylinder extending radially from the crankshaft and a heat dissipating fin on the outer periphery of the cylinder. The fan cover that forms the casing oscillates in resonance with the vibration generated by the engine, and the cover itself vibrates violently to generate noise, as well as loosening or dropping off of nearby mechanical parts, eventually causing mechanical failure. There were problems that impaired the reliability of air-cooled engines.

  One method for mounting the cooling fan cover on the engine block while preventing resonance with the engine is disclosed in Patent Document 1 (Japanese Patent No. 2691461) and Patent Document 2 (Japanese Utility Model Publication No. 61-33224). As announced, bolt holes into which rubber grommets are fitted are provided at a plurality of locations on the periphery of the fan cover, and the cooling fan cover is connected to the cylinder block by a plurality of bolts through the holes of the grommets. It is a method of elastic support.

According to this method, by appropriately selecting the size and material of the rubber grommet and adjusting the tightening force of the bolt, the natural frequency of the fan cover can be removed below the normal rotational speed range of the engine. However, since the fan cover itself is only elastically supported and connected, it is an unstable mounting method that is displaced vertically and horizontally by an unexpected external force.
In addition, since it is necessary to process a plurality of short cylindrical throttle holes that can receive the rubber grommets in the peripheral portion of the fan cover, there is a problem that the structure of the fan cover becomes complicated.

As disclosed in Patent Document 3 (Japanese Patent No. 3686202), a technique for mounting a cooling fan cover on a cylinder block without amplifying vibration and noise generated by an engine is disclosed. There is a method of fixing the casing with a plurality of bolts while sandwiching a synthetic resin molding material between the same part) and the cylinder block.
In this case, if an appropriate elastic resin and pinching allowance is selected as the synthetic resin molding material to be pinched, only the suppressed engine vibration and noise are transmitted to the wind guide casing. Resonance and resonance can be avoided by virtue of the vibration damping capability of the sandwiched material.

The problem is that an appropriate thickness can be obtained considering the elasticity and clamping pressure of the synthetic resin molding material, or the synthetic resin molding material is crimped to the cylinder block with a predetermined clamping pressure. In order to do this, it is necessary to perform elaborate recess processing on the front surface of the cylinder block.
According to this method, the wind guide casing is fastened and fixed to the cylinder block with a plurality of bolts, so that the mounting can be performed easily and reliably.

As a result of the noise analysis of the engine cooling fan cover, it was found that the cover as a whole, in addition to the strong noise generated in resonance with the engine vibration, contained relatively weak but annoying noise in the high sound range. As a result of the test, it was also found that the resonance film vibration was in the flat part of the fan cover.
Patent Document 4 (Japanese Utility Model Laid-Open No. 56-85050) discloses a structure for preventing vibration generated by an engine from being transmitted to a flat portion of an engine cover such as an oil pan or a head cover to amplify noise as membrane vibration. ), A method of adding a plurality of damping material blocks by inserting them into slits provided in the oil pan plane portion is known.
In the cooling fan cover described above, even if the vibration level of the fan cover as a whole is lowered due to the vibration-proof support, relatively high-frequency noise derived from the membrane vibration of the flat part of the cover and the approximate flat part remains. The vibration effect was difficult to recognize. Therefore, in order to realize a cooling fan cover that functions quietly and stably, it is necessary to reduce high-frequency noise caused by the membrane vibration.

Japanese Patent No. 2691461 (FIG. 9) Japanese Utility Model Publication No. 61-33224 (FIGS. 2 and 4) Japanese Patent No. 3686202 (FIG. 4) Japanese Utility Model Publication No. 56-85050 (Fig. 3)

The first problem to be solved is to improve the support structure for vibration isolation and to facilitate the characteristic adjustment. As disclosed in Patent Document 1 and others, in order to fit rubber grommets into the fan cover tightly and hold them down with bolts, it is precisely short cylinder-shaped at a predetermined position on the peripheral edge of the fan cover where the grommets are mounted. It is necessary to process the aperture hole. In addition, the diameter and the length of the short cylindrical throttle hole also require a considerable sheet metal processing technique, such as a dimension that matches the body diameter and groove width of the rubber grommet.
Furthermore, in order to attach the fan cover to the cylinder block and exhibit the predetermined vibration-proof performance, it is necessary to adjust not only the grommet dimensions but also the rubber hardness and the tightening level of the mounting bolts. Depending on the variation in the processing accuracy of the related parts, troublesome adjustment is required.
Therefore, there is a need to provide a fan cover support method and structure that have a simple support structure and can be easily adjusted for vibration isolation.

The second problem is instability of a method in which a rubber grommet proposed in Patent Document 1 and others is used as a vibration isolating material, and a fan cover is floated on the rubber grommet and attached to the cylinder block. That is, since the fan cover is placed on a rubber vibration isolator and has a natural frequency smaller than the normal engine speed of an ordinary engine, when an abnormal rotational reaction force (for example, an impact caused by stopping the engine) is applied, There is a possibility of rocking violently.
Further, in general-purpose air-cooled engines having various uses, an unexpected external force may be applied to the entire engine or the fan cover on the side opposite to the output shaft, so that the above mounting method causes problems and damages.
In order to solve these problems, it is necessary to provide a support method and structure that does not resonate at the normal rotation speed of the engine while the fan cover is fixed to the cylinder block.

The third problem is to provide a simple structure for effectively suppressing the vibration of the fan cover while fixing the periphery of the cooling fan cover to the cylinder block with a plurality of bolts. is there. That is, since the vibration generated by the engine is transmitted to the fixed point of the fan cover via the cylinder block, the vibration transmitted from the fixed point to the fan cover main body part is mitigated by the buffer material or the elastic body, It is necessary to devise a configuration that does not resonate with the normal engine speed.
The contrivance does not require complicated processing of related parts and may have a structure that makes it easy to adjust the natural frequency of the fan cover to be sufficiently higher than the vibration range of the cylinder block. is necessary.

A fourth problem is to limit relatively high-frequency noise from the cooling fan cover during normal engine rotation.
The cooling fan cover includes a wind guide portion for guiding the cooling air, a pressure contact portion to the cylinder block, and the like, and includes a considerable amount of a plane portion or an approximate plane portion that causes membrane vibration. In particular, the plane or approximate plane in the vicinity of the cylinder block that is a noise source may cause resonance membrane vibration at a high frequency and generate noise even if the entire cooling fan cover is supported by vibration isolation. .
It has been necessary to suppress the resonance membrane vibration that is likely to occur in the flat portion or the approximate flat portion by using a vibration-proof material or a vibration-proof method for supporting the entire cooling fan cover in a vibration-proof manner.

With respect to the above problems, the present invention aims to solve the problems by the following means.
(1) A first means is a cooling fan cover for a forced air-cooled engine having a structure in which a plurality of fixing legs provided on the periphery are directly fixed to a cylinder block with bolts, and the fan resonates with vibration generated by the cylinder block. In order to prevent the cover from vibrating with the legs as nodes and generating noise or the like, a soft vibration isolator is sandwiched between the vibrating main part of the periphery of the fan cover, and the soft vibration isolator is opposed to the cylinder block When mounting so as to be in pressure contact with the surface, the soft anti-vibration material has a thick C-shaped anti-vibration material, and the bottom surface is clamped and fixed between the lower end surface of the fan cover and the surface of the cylinder block. The resonance area of the fan cover is removed above the normal operating range of the engine, and the upper end of the C-shaped vibration isolator is attached to the fan cover plane part and the approximate plane part. Anti-vibration of a cooling fan cover for a forced air cooling engine that is pressed and inserted into the slit and joined to absorb and suppress the membrane vibration generated on the flat part and approximate flat part of the fan cover・ Sound control support method.

  (2) The second means is a cooling fan cover for a forced air cooling engine having a structure in which a plurality of fixing legs provided on the periphery are directly fixed to the cylinder block with bolts, and the fan resonates with vibration generated by the cylinder block. In order to prevent the cover from vibrating with the legs as a node and generating noise or the like, a clearance slightly less than the thickness of the soft vibration isolator is provided on the periphery of the fan cover, and the clearance is formed. The end face of the cooling fan cover has a narrow flange, and a slit is provided in the side plane portion and the approximate plane portion of the fan cover, and the cross section is thick between the clearance allowance and the end face of the cylinder block. The soft vibration isolator formed in a C-shape is sandwiched, and the lower part of the vibration isolator is held by clamping and fixing with the cylinder block, and the soft vibration isolator For forced air-cooled engine eaves-like projecting portion formed in the end portions so as to have such bonding press-fitted to the slit disposed in the cover cooling fan cover.

(3) The third means is the cooling fan cover for forced air cooling engine of the second means, wherein the soft vibration isolator is integrally formed between the bowl-shaped projecting portion and the lower portion by a thick body trunk. A cooling fan cover for a forced air-cooled engine that is a connected C-shaped soft vibration-proof and sound-damping material.

  (4) A fourth means is a vertical fan cooling fan cover for the forced air cooling engine of the third means, having a shape in which a vibration absorbing mass is added to the body of the tall C-shaped soft vibration-proof and sound-damping material. Cooling fan cover for forced air-cooled engines, which is a type M-shaped anti-vibration and sound-damping material.

(5) A fifth means is a cooling fan cover for a forced air cooling engine according to the third means, wherein the body portion of the tall C-shaped soft vibration-proof and sound-damping material is also provided with a hook-like protrusion, A cooling fan cover for a forced air-cooled engine, characterized in that it is a tall E-shaped soft vibration-proof and sound-damping material configured to be able to hold the flat surface portion or approximate flat surface portion of the fan cover together with the hook-shaped protrusion of the portion. .

  The invention according to claim 1 is a simple and stable cooling fan in which the cooling fan cover of the forced air cooling engine is securely attached to the cylinder block and does not resonate with any vibration generated in the normal rotation speed range of the engine. A method of attaching a cover can be provided.

According to a second aspect of the present invention, there is provided a film in which the vibration isolator used for mounting the cooling fan cover is securely fixed to the cooling fan cover, and is generated in the flat portion and the approximate flat portion of the fan cover. By absorbing and attenuating vibration, it is possible to provide a sound damping material that suppresses high-frequency noise.
In addition, confirm the length of the vibration isolating material having a high anti-vibration effect and the mounting position of the material by a test or the like, and attach the clearance allowance only to the location corresponding to the length and position of the peripheral edge of the cooling fan cover. By doing so, it is possible to provide a structure capable of minimizing the leakage of cooling air, and to provide an effective means for adjusting the vibration isolation of the structure.
Furthermore, the cooling fan cover with the added value is constructed so that it can be assembled in the most economical and stable manner, and can be applied to a forced air cooling engine that is actually used, so that stable and quiet operation is possible at all times. A cooling fan cover for a forced air cooling engine can be provided.

The invention according to claims 3, 4 and 5 makes it possible to adjust the vibration absorption characteristics of the vibration isolator used for mounting the cooling fan cover, and occurs in the flat surface portion and the approximate flat surface portion of the fan cover. In order to efficiently absorb and dampen membrane vibration, it is possible to provide a vibration proofing / damping material that effectively suppresses high-frequency noise.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a cooling fan cover in a forced air-cooled engine in a state where a tall C-shaped soft vibration-proof and sound-damping material having a thick cross section is mounted. Shows the inner surface. FIG. 2 shows a cooling fan cover to which the present invention is applied, in a side sectional view of a forced air cooling engine. FIG. 3 is a bottom view of the cooling fan cover of FIG. 1 viewed from the S direction. FIG. 4 is a side view of the cooling fan cover as seen from the N direction. FIG. 5 is a side view of the cooling fan cover as seen from the W direction.

FIG. 6 shows a schematic vibration model of one component part of the cooling fan cover in order to facilitate understanding of a state in which the cooling fan cover to which the present invention is not applied resonates with the engine. FIG. 7 is a vibration model schematically showing the same components as those in FIG. 6 in order to facilitate understanding of how the cooling fan cover to which the present invention is applied changes in vibration characteristics. FIG. 8 is a detailed view of a portion A in FIG. 2 showing a portion where the cooling fan cover is securely fixed to the cylinder block by bolts. FIG. 9 shows a state in which a soft vibration-proof and sound-damping material having a tall C-shaped cross section according to the present invention is mounted on the periphery of the cooling fan so as to exhibit vibration-proof and sound-damping functions. FIG.

In the cross-sectional view of the forced air-cooled engine 10 in FIG. 2, the crankshaft 1 is gripped rotatably by a pair of crank bearings 3 fitted in the cylinder block 2. An output shaft 1a is provided at one end of the crankshaft 1. A cooling fan rotor 4 that also serves as a flywheel is fixed to the opposite output side shaft 1b at the other end. A cooling fan cover 5 serving as a role surrounds and is fixed to the cylinder block 2 by a plurality of fixing legs 5a and fixing bolts 6 as shown in FIG. (How to refer to FIG. 8, which is a detailed sectional view of part A)
The portions other than the fixing legs 5a at the peripheral edge of the cooling fan cover 5 are opposed to the cylinder block 2 with a slight clearance, or the cross section is a tall C-shaped soft vibration-proof and sound-damping material 7. The cylinder block 2 is pressed against the lower portion of the cylinder block 2. (See FIG. 9). Reference numeral 8 denotes a recoil starter cover.

FIG. 1 is a plan view of the cooling fan cover 5 according to the present invention in a state where all of the tall C-shaped soft vibration-proof and sound-damping material 7 are fitted, viewed from the cylinder block 2 side (the front side of the paper). The inner surface of the cooling fan cover 5 is shown. If the fan cover 5 is fixed to the cylinder block 2 with a plurality of bolts 6 without attaching the soft vibration-proof and sound-damping material 7 to the fan cover 5, the engine air Resonating with the generated vibration, the fan cover 5 is greatly vibrated, and the state of the vibration is investigated. On the other hand, the tall C-shaped soft vibration-proof and sound-damping material 7 of the present invention is mounted, and the bolt 6 to investigate the vibration state of the cooling fan cover 5 fixed to the cylinder block 2, it should be confirmed that the natural frequency of the fan cover 5 has moved above the frequency of the forced air cooling engine 10. is there. Based on this, a configuration for avoiding resonance will be described below.

For this purpose, first, it is necessary to elucidate the vibration of the fan-shaped portion a that has the fixing points a and b of the cooling fan cover 5 by the bolts 6 as the outer periphery and requires the center of the central circular opening.
Similarly, the vibration of the fan-shaped part a having the fixing points b and c of the cooling fan cover 5 as the outer periphery, the vibration of the fan-shaped part c having the fixing points c and d as the outer periphery, and the fixing points d and a of the cooling fan cover 5 In order to finally elucidate the vibration mode of the cooling fan cover 5 before and after the resonance region, the vibrations of the four parts of the fan-shaped parts a, i, c, and d are considered. If the synthesized vibration is discussed, the vibration before and after resonance of the entire cooling fan cover 5 can be explained.
Therefore, in FIG. 3, the equivalent mass Wab of the fan-shaped portion a having the outer periphery of the bolt fixing points a and b, the bending elastic modulus Ka and Kb expected to the leg plate of the bolt fixing points a and b of FIG. The vibration model shown in FIG. 7 is considered from the longitudinal elastic modulus K1 and the damping capacity d1 of the lower part of the C-shaped soft vibration-proof and sound-damping material 7.

First, in the case of the cooling fan cover 5 to which the present invention is not applied, in FIG. 3, the tall C-shaped soft vibration-proof and sound-damping material 7 is missing, so that the vibration model is a longitudinal elastic modulus K1. 6 where the damping capacity d1 is lost, the total elasticity of the vibration model is small, and a lower natural frequency than that of the vibration model of FIG. 7 is given to the same equivalent mass Wab.
This means that even if the vibration model of FIG. 6 resonates with the vibration of the engine, the natural vibration of the vibration model (FIG. 7) of the fan-shaped part which is one component of the cooling fan cover according to the present invention is outside the resonance region. It is high and shows that it is stable.

According to the same reasoning, the fan-shaped portion C and the equivalent mass Wcd with the bolt fixing points c and d shown in the side view of the cooling fan cover 5 in FIG. 4 as the outer periphery, the bending elastic modulus Kc and Kd of the leg plate, and the soft protection The vibration model (FIG. 7) of the fan-shaped portion C, which is one component of the cooling fan cover 5 according to the present invention, has a resonance region due to the effects of the longitudinal elastic modulus K3 and the damping capacity d3, etc. Shown to be stable above.
As for the fan-shaped portion a (shown in side view in FIG. 5) and d, which are other components of the fan cover 5, the above-mentioned reasoning can be applied as it is, so that repeated explanation is omitted, but as a result, It can be concluded that the combined vibrations of the fan-shaped parts such as a, u, and d become stable with the resonance region raised upward.

The determination of how much the natural frequency of each component of the cooling fan cover 5 is adjusted above the resonance range is based on the condition that the combined vibration, which is the vibration of the entire fan cover, is the smallest and stable. Determine by exploring experimentally. For that purpose, it is important that the cross section can adjust the application length and application position of the tall C-shaped soft vibration damping / sound damping material 7.
In the present invention, the soft vibration-proof and sound-damping material 7 is a mold having a uniform tall C-shaped cross section in the longitudinal direction so that the length can be easily adjusted with a normal blade, and the fan A clearance r (see FIG. 9) and a narrow flange 5f so that the lower portion 7a of the soft vibration-proof and sound-damping material 7 can be fitted are provided in the vicinity of the vibration belly of the cover peripheral portion. The lower part 7a of the soft vibration-proof / sound damping material 7 can be freely adjusted in length within the range of the clearance allowance r and the length of the flange 5f.
Further, the dimension of the clearance r provided at the peripheral edge portion of the fan cover 5 needs to be set slightly smaller than the thickness of the lower portion 7a of the soft vibration-proof and sound-damping material 7. That is, the peripheral edge of the fan cover 5 contacts the cylinder block 2 even when the fixing bolt 6 is fully tightened and the lower portion 7a of the soft vibration-proof and sound-damping material 7 is pinched and deformed as shown in FIG. It is good that the gap of not to be kept.

The cooling fan cover 5 emits special vibrations in the normal operating range of the engine mainly due to the effect of the elasticity and damping capacity of the lower part 7a of the soft and vibration-damping material 7 having a thick and tall C-shaped cross section. However, the soft vibration-proof and sound-damping material having a tall C-shaped cross section is also used for high-frequency noise derived from the membrane vibration of the flat surface portion and the approximate flat surface portion of the fan cover 5. The hook-like protruding portion 7b at the upper end is joined to the center of the membrane vibration to act to absorb and suppress vibration / noise.
That is, the membrane vibration of the flat surface portion and the approximate flat surface portion of the cooling fan cover 5 is joined by pressing and fitting the hook-shaped protrusion 7b of the upper end portion into the slit s provided on the flat surface portion and the approximate flat surface portion. Is transmitted to the main body trunk portion 7c of the tall C-shaped soft vibration damping and sound damping material 7, and the energy of the membrane vibration is caused by the elasticity and damping capacity of the main body barrel portion 7c of the soft vibration damping and sound damping material 7. Absorbed and limited. In other words, the membrane vibration generated in the fan cover 5 is suppressed by absorbing the energy by the tall C-shaped soft vibration-proof and sound-damping material 7.

A feature of the embodiment of the present invention is that a plurality of fixing legs 5a are provided on the peripheral edge of the cooling fan cover 5, and a plurality of fixing bolts 6 passing through a central hole of the legs are tightened to thereby provide the fan. The cover 5 is securely attached to the cylinder block 2.
The fixing leg 5a is a flat plate protruding like a tongue provided at the peripheral edge of the pan-shaped cooling fan cover 5 with the bottom center part removed. The leg portion 5a still has bending elasticity, and the peripheral portion of the fan cover 5 with the position of the pair of fixing bolts 6 as a node vibrates, but the vibration, the flat portion of the fan cover 5 and the approximate portion High-frequency noise caused by membrane vibration generated in the flat surface portion can also be prevented by attaching a tall C-shaped soft vibration-proof and sound-damping material having a thick cross section to the peripheral edge portion.

The soft vibration-proof and sound-damping material 7 is interposed at the peripheral edge between the fixing bolts 6 of the fan cover 5 to reinforce the elasticity and vibration damping force for supporting the fan cover 5 having an equivalent mass (see FIG. 7), the natural vibration compared to the conventional cooling fan cover 5 (refer to the vibration model of FIG. 6) without the tall C-shaped soft vibration-proof and sound-damping material 7. In the end, the natural frequency of the fan cover 5 is increased by synthesizing the natural vibrations of the fan-shaped portions a, i, c, and d (see FIG. 1) of the fan cover 5. I can do it.
The tall C-shaped soft vibration-proof / sound-damping material can change the elastic force and the vibration damping force with respect to the fan cover 5 by changing its length.

In the present invention, the cooling fan cover 5 that is fastened and fixed, and the lower portion 7 a of the thick, tall C-shaped soft vibration-proof and sound-damping material 7 that is sandwiched between the cylinder block 2, The upper end of the C-shaped soft vibration-proof and sound-damping material 7 is hooked into a slit s disposed horizontally at the center position of the fan cover 5 so as to be held at the peripheral edge. The portion 7 b is pressed and inserted, and is configured to be joined and held with the flat portion and the approximate flat portion of the fan cover 5.
Further, in order to minimize the cooling air leaking from the gap between the fan cover 5 and the cylinder block 2, the peripheral edge of the fan cover 5 into which the lower portion 7 a of the soft vibration-proof and sound-damping material 7 is fitted is A recess having a clearance allowance r slightly smaller than the wall thickness of the vibration-proof / sound-damping material 7, that is, a right-angle bent flange 5 f is provided, and the soft vibration-proof / sound-damping material 7 lower portion 7 a is connected to the flange 5 f. The size of the clearance allowance r is set so that the general peripheral edge of the fan cover 5 does not come into contact with the cylinder block 2 and the minimum clearance is maintained even if the pressure is sandwiched between the cylinder block 2 and the cylinder block 2. To do.
(Second Embodiment)

The second embodiment is different from the first embodiment in that the cross section of the soft vibration-proof and sound-damping material of the first embodiment is a tall C-shape. The soft vibration-proof material / sound-damping material of the second embodiment forms a bulge in the body portion having a tall C-shaped cross section so that the top of the bulge comes into contact with the flat surface portion and the approximate flat surface portion of the cooling fan cover. That is, it has a vertical M-shape with a simple cross-sectional shape. Functionally, it is substantially equivalent to the tall C-shaped soft vibration-proof and sound-damping material of the first embodiment. The second embodiment will be described below with reference to the drawings.

FIG. 10 is a cross-sectional view showing a place where the soft vibration-proof and sound-damping material 17 having the vertical M-shaped cross section is attached to the cooling fan cover 5. The soft vibration damping / sound damping material 17 includes a flange 5f with a clearance allowance r in which a lower portion 17a is provided on the peripheral edge of the fan cover 5 and a cylinder, like the tall C-shaped vibration damping / sound damping material 7. The upper end of the fan cover 5 is pressed and inserted into the slit s disposed horizontally at the center position of the fan cover 5. The flat portion and the approximate flat portion are joined and held.
Note that the top surface of the bulge of the main body trunk portion 17c of the vertical M-shaped cross-section soft vibration-proof / sound-damping material 17 is connected to the fan-shaped projection 17b at the upper end when the fan-shaped projection 17b is fitted into the slit s and coupled. It shall be shape | molded so that it may contact the plane part of a cover, and an approximate plane part reliably.
The contact is necessary for the energy of the membrane vibration of the fan cover 5 flat surface portion and the approximate flat surface portion to be effectively transmitted and absorbed to the entire soft soundproofing / damping material 17.
(Third embodiment)

FIG. 11 is a cross-sectional view showing a state where the tall E-shaped soft vibration-proof / sound-damping material 27 according to the first embodiment is attached to the cooling fan cover 5. The main body part 7c of the front and back high C-shaped soft vibration-proof and sound-damping material 7 has a shape in which a hook-like protrusion 27c having almost the same structure as that of the upper part is added. The cover 5 is pressed and fitted into a horizontal slit s disposed at a corresponding position and joined.
The upper and lower hook-like protrusions 27b and 27c when the hook-like protrusion 27b on the upper end and the hook-like protrusion 27c on the body are pressed and fitted into the respective slits s and joined to the cooling fan cover 5. Are configured so as to apply force to each other because there is a slight difference in the longitudinal dimension. The internal forces applied to each other cause the E-shaped soft vibration-proof / sound-damping material 27 to come into close contact with the flat surface portion and the approximate flat surface portion of the fan cover 5, and the energy of the membrane vibration generated in the flat surface portion and the approximate flat surface portion. Is necessary to effectively transmit and absorb.
(Fourth embodiment)

FIG. 12 shows the thick main body 7c of the tall C-shaped soft vibration-proof and sound-damping material 7 described in the first embodiment, and the upper protrusion 7b is directly joined to the lower part. Sectional drawing of the made C-shaped soft vibration-proof material 37 is shown. This is an embodiment that can be used when a curved surface is frequently used or the thickness of the plate is increased and the membrane vibration of the flat portion and the approximate flat portion is attached to the cooling fan cover 5 designed so as not to contribute to noise. .
The upper end of the C-shaped soft vibration isolator 37 is pressed and fitted into the slit s of the fan cover 5 and the lower part is clamped and pressed by the small flange 5f of the fan cover 5 and the end face of the cylinder block 2. Since it is fixed, the support elasticity is increased, the natural frequency of the cooling fan cover 5 is increased, and it is stabilized so as not to resonate in the normal operation range of the engine.
The C-shaped soft vibration isolator 37 is also characterized in that it is formed vertically symmetrically around the groove into which the flange 5f is inserted in order to prevent erroneous work when assembled to the cooling fan cover 5. .

In the forced air cooling engine to which this invention is applied, it is a front view of the cooling fan cover in the state where the soft vibration-proof and sound-damping material is mounted. It is a sectional side view of the engine which shows the attachment site | part of the cooling fan cover by this invention. FIG. 2 is a bottom view of the cooling fan cover of FIG. 1 viewed from the direction S. FIG. 2 is a top view of the cooling fan cover of FIG. 1 as viewed from the N direction. It is the side view which looked at the cooling fan cover of FIG. 1 from the direction of W. It is a vibration model of one component of the cooling fan cover when the present invention is not applied. It is a vibration model of one component part of the cooling fan cover at the time of applying this invention. FIG. 3 is a detailed cross-sectional view showing a portion in which the cooling fan cover is securely fixed to the cylinder block by bolts, and is a detailed cross-sectional view of part A in FIG. 2. The tall C-shaped soft vibration-proof and sound-damping material according to the first embodiment of the present invention is fitted in the cooling fan cover peripheral edge and is mounted so as to exhibit the vibration-proof and sound-damping function. FIG. 3 is a detailed cross-sectional view, and is a detailed cross-sectional view of a portion B in FIG. The vertical M-shaped soft vibration-proof and sound-damping material according to the second embodiment of the present invention is fitted in the peripheral edge of the cooling fan cover so as to exhibit the vibration-proof and sound-damping function. FIG. The tall E-shaped soft vibration-proof and sound-damping material of the third embodiment of the present invention is fitted to the peripheral edge of the cooling fan cover so as to exhibit the vibration-proof and sound-damping function. FIG. It is a cross-sectional detail figure of the state with which the C-shaped soft vibration-proof material of the 4th Embodiment of this invention was mounted | worn so that it might be fitted in the cooling fan cover peripheral part edge part, and the vibration-proof function might be exhibited.

Explanation of symbols

2 Cylinder block 5 Cooling fan cover 5a Fixing leg 5f Flange 6 Bolt 7 Tall C-shaped soft vibration damping / damping material 17 Vertical M-shaped soft vibration damping / damping material 27 Tall E-shaped soft vibration damping / damping Sound material 37 C-shaped soft vibration-proof material 10 Forced air-cooled engine 7a, 17a Lower part 7b, 17b, 27b, 27c Gutter-like protruding part 7c, 17c Body trunk part r Escape allowance s Slit

Claims (5)

  In a cooling fan cover for a forced air cooling engine configured to directly fix a plurality of fixing legs provided on the periphery to the cylinder block with bolts, the fan cover vibrates with the legs as nodes, resonating with vibration generated by the cylinder block. In order to prevent noise and the like from occurring, a soft vibration isolator is sandwiched in the vibrating main portion of the fan cover periphery, and the soft vibration isolator is mounted so as to be in pressure contact with the surface of the cylinder block facing the soft vibration isolator. At this time, the shape of the soft vibration damping material is a C-shaped vibration damping material with a thick cross section, and the bottom surface is clamped and fixed between the lower end surface of the fan cover and the surface of the cylinder block to thereby increase the resonance range of the fan cover. The upper end of the C-shaped anti-vibration material is pressed against the slits attached to the fan cover plane part and the approximate plane part. The anti-vibration of the cooling fan cover for forced air-cooled engine, which is made to function as a sound-damping material that absorbs and suppresses membrane vibration generated in the flat part and approximate flat part of the fan cover.・ Sound control support method.   In a cooling fan cover for a forced air cooling engine configured to directly fix a plurality of fixing legs provided on the periphery to the cylinder block with bolts, the fan cover vibrates with the legs as nodes, resonating with vibration generated by the cylinder block. In order to prevent noise and the like from being generated, a clearance slightly less than the thickness of the soft vibration isolator is provided on the periphery of the fan cover, and the end surface of the cooling fan cover that forms the clearance is narrow. A soft vibration isolator having a flange having a width and having slits in the side plane portion and the approximate plane portion of the fan cover and formed into a thick C-shaped section between the clearance and the end face of the cylinder block. While holding the material to hold the lower part of the anti-vibration material by sandwiching and fixing between the cylinder block, the heel formed at the upper end of the soft anti-vibration material Forced air cooling engine cooling fan cover, characterized in that the protruding portions so as to have such bonding press-fitted to the slit disposed in the cover.   3. A cooling fan cover for a forced air-cooled engine according to claim 2, wherein the soft vibration isolating material is integrally connected between the hook-shaped projecting portion and the lower portion by a main body body having a thick cross section. A cooling fan cover for a forced air cooling engine, characterized by sound material.   4. A cooling fan cover for a forced air-cooled engine according to claim 3, wherein the vertical C-shaped soft vibration damping / sound damping material has a shape in which a vibration absorbing mass is added to the body portion of the tall C-shaped soft vibration damping / sound damping material. A cooling fan cover for a forced air cooling engine.   4. A cooling fan cover for a forced air cooling engine according to claim 3, wherein said tall C-shaped soft vibration-proof and sound-damping material is provided with a hook-like protrusion on the trunk thereof, together with a hook-like protrusion at the upper end. A cooling fan cover for a forced air-cooled engine, characterized by being a tall E-shaped soft vibration-proof and sound-damping material configured to hold a flat surface portion or an approximate flat surface portion.

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