EP0046923A2

EP0046923A2 - Noise reducing cover

Info

Publication number: EP0046923A2
Application number: EP81106412A
Authority: EP
Inventors: Naoki Ogawa
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1980-08-28
Filing date: 1981-08-18
Publication date: 1982-03-10
Also published as: EP0046923A3; JPS5744952U

Abstract

A noise reducing cover (10) comprising a retainer member (24) secured to a structural member (12) capable of being vibrated and formed with a groove (24b), a cover member (11) whose major part (22) is made of a material high in damping capacity, the cover member being formed with an edge section (11a) which is disposed within the retainer member groove (24b), and an elastic member (28) interposed between the surface of the retainer member groove (24b) and the surface of the cover member edge section (11a), thereby effectively preventing the vibration of the vibrating structural member (12) from transmitting to the cover member and preventing noise emission from the cover member surface.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a noise reducing arrangement applicable to covers such as an oil pan, rocker cover used for internal combustion engines and the like.

2. Description of the Prior Art

Covers for moving parts of internal combustion engines, as in cylinder head covers (rocker covers), oil pans, valve lifter covers, and the like have traditionally been formed from sheet metal. Solid sheet metal is hardly a vibration or sound absorbing material; in fact, solid metal is one of the best sound and vibration conductors as well known. When a cylinder head cover or the like is rigidly mounted to an internal combustion engine, which of course, it must be in order to perform its intended function, the cover itself becomes an excellent conductor of noise and vibration produced by the internal combustion engine. In fact, due to the shape of certain types of such covers having large, essentially flat sections, these covers become excellent amplifiers of engine noise. Additionally, engine vibration is transmitted to the particular cover, thus creating another source of noise, i.e. the vibration of the SUMMARY OF THE INVENTION
In accordance with the present invention, a noise reducing cover comprising a retainer member secured to a structural member which can be vibrated, the retainer member being formed with a groove. A cover member is formed with an edge section which is securely disposed within the groove of the retainer member. The major part of the cover member is made of a material which is high in damping capacity, An elastic member is interposed between the surface of the retainer member groove surface and the cover edge section surface. With this arrangement, the vibration of the structural member to which the retainer is secured is prevented from transmitting to the cover member by virtue of the elastic member. If the vibration is transmitted to the cover member, the cover member made of the high damping capacity material damps the transmitted vibration, thereby effectively prevent noise emission from the surface of the cover member.

DESCRIPTION OF THE DRAWINGS

The features and advantages of the noise reducing cover according to the present invention will be more clearly appreciated from the following description taken in conjunction with the accompanying drawings in which like reference numerals designate the corresponding parts and elements, in which:

Fig. 1 is a cross-sectional illustration of a preferred embodiment of a noise reducing cover (engine side cover) in accordance with the present invention;
Fig. 2 is an enlarged sectional view of a part enclosed by a dot-dash circle II of Fig. 1;
Fig. 3A is a cross-sectional view of a modified example of the engine side cover in accordance with the present invention;
Fig. 3B is an enlarged sectional view of a part enclosed by a dot-dash circle IIIB of Fig. 3A;
Fig. 4A is a partial side elevation of a retainer member of a further embodiment of the engine side cover according to the present invention;
Fig. 4B is a sectional illustration showing the construction of the engine side cover of Fig. 4A; and
Fig. 5 is a cross-sectional view of another embodiment of the noise reducing cover (rocker cover) in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to Figs. 1, 2A and 2B of the drawings, there is shown a preferred embodiment of a noise reducing cover 10 in accordance with the present invention.
The noise reducing cover (engine side-cover) 10, in this instance, is used for covering a lower section of an engine body 12, for example, of an automotive vehicle. As shown in Fig. 1, the engine body 12 consists of a cylinder block 14 formed therein with an engine cylinder 14a. A crank-frame construction 16 is secured to the bottom section of the cylinder block 14, forming a cylindrical opening 18 for a crankshaft (not shown) between it and the bottom section of the cylinder block 14. A pair of the noise reducing covers or engine side covers 10 are disposed oppositely on the opposite sides of the engine body 12 so that each engine side cover 10 covers an open or exposed section 10a of the engine body 12, maintaining a liquid and gas-tight seal. As shown, the engine cover 10 extends from the cylinder block 12 to the crank-frame construction 16.
As best seen from Fig. 2B, the engine side cover 10 comprises a cover member 11 of the double-layer construction. The cover member 11 consists of an inner layer 20 made of a material which has ah oil-and water-proof ability or an ability to prevent oil and water from passing therethrough. Such a material is, for example, rubber, or plastics. An outer layer or main body 22 is securely attached to the inner layer 20 and made of a structural material, high in damping capacity, such as a plastic material, a fibrous material, rubber, or foam metal. The outer layer 22 constitutes a major part of the cover member 11 and therefore larger in volume than the inner layer 20. Accordingly the cover member 11 exhibits a vibration and sound absorbing effect. The cover member 11 is thus generally in the form of a plate and is formed with an edge section 11a along its periphery.
A retainer member 24 is secured at its base or attachment surface B to the outer surface of the engine body 12 in a manner to surround the open section 12a of the engine body 12, maintaining a gas and oil-tight seal relative to the engine body surface. The retainer member 24 is made of a high rigidity material such as rigid plastics, metal, or the like, and formed with holes 24a through which bolts 26 pass and screwed into the engine body 12 so that the retainer member 24 is fixed onto the engine body surface. In this instance, the retainer member 24 is formed in the shape of a closed loop and formed at its inner periphery with a groove 24b into which the edge section 11a of the engine side cover 11 is securely inserted. As shown, the groove 24b is defined between parallel outer and inner plate sections P₁ and P₂. It is to be noted that the inner wall surface of the groove 24a is covered with a member 28 made of an elastic or elastomeric material such as rubber, or the like. In other words, the elastic member 28 is interposed between the wall surface of the groove 24b and the surface of cover member edge section 11a, so that the retainer member 24 securely supports the cover member edge section 11a through the elastic member 28.
In order to install the engine side covers 10 onto the cylinder block 14 and the crank-frame construction 16 of the engine body 12, it is preferable to previously fit the edge section 11a of each cover member 11 in the groove 24b of the retainer member 24, and thereafter to fasten the retainer member 24 onto the surface of the engine body 12 through a gasket (not shown) by tighening the bolts 26.
With the thus arranged engine equipped with the engine side covers 10, engine vibration is first transmitted to the retainer member 24; however, such a vibration is scarcely transmitted to the cover member 11, because the vibration is absorbed by the elastic member 28 disposed within.the groove 24b of the retainer 24. If the vibration is transmitted to the cover member 11, such a vibration has been, as mentioned above, already damped to an appreciable extent, and further damped by the high damping capacity layer 22 of the engine side cover member 11. This greatly suppresses noise emission from the outer surface of the engine side cover 10, thereby extremely decreasing engine noise.
It will be understood that since the retainer member 24 is made of the material which is high in rigidity, the retainer member can tightly contact the attachment surface of the engine 12, thereby effectively preventing lubricating oil etc. from leaking out through a section where the retainer member 24 is installed. Additionally, since the cover member 11 is press-fitted into the elastic member 28 within the retainer member groove 24b, there is no apprehension that the cover member 11 gets out of the retainer member 24, maintaining a high sealing ability even during high engine load and high power output engine operation in which engine vibration is enormous.
Figs. 3A and 3B shows a modified example of the engine side cover 10 according to the present invention. This embodiment is similar to the embodiment of Figs. 1 to 2B with the exception that the outer plate section P₁ of the retainer member 24 is smaller in width than the inner plate section P₂. In other words, the outer plate section P₁ is shaped so that a major part containing its peripheral edge is cut out. Accordingly, the groove 24b of the retainer member 24 is shallow particularly in connection with the outer plate section P₁, as compared with in the embodiment of Figs. 1 to 2B. With this arrangement, the installation of the cover member 11 to the retainer member 24 can be facilitated, thereby shortening the time required for assembling an engine.
Figs. 4A and 4B show a further embodiment of the engine side cover in accordance with the present invention. In this embodiment, the retainer member 24 is so formed that the parallel plate sections P₁₁ P₂ perpendicular to the base surface B which is attached to the attachment surface of the engine body 12, and extend outwardly, so that the groove 24b is perpendicular to the retainer member base surface B. With this arrangement, the cover member 11 can be fitted into the retainer member groove 24b merely by horizontally pushing the cover member 11 so that the edge of the cover member 11 to is inserted into the retainer member groove 24b. This can further facilitate the assembly operation of the engine.
It will be understood that, in all the embodiments, the retainer member 24 may be formed integrally with a gasket on its attachment surface through which retainer member 24 is attached to the engine surface, which contributes to a further improvement in sealing ability and in operation efficiency in assembling engine.
Additionally, the retainer member 24 may be constituted by a plurality of independent pieces, thereby facilitating the installation of the cover member 11 to the retainer member 24.
Fig. 5 shows another embodiment of the noise reducing cover according to the present invention, in the form of a rocker cover or cylinder head cover. The rocker cover 30, in this instance, comprises a cover body 32 or cover member whose major part is made of a material which is high in damping capacity. The cover body 32 may be made of the same material as in the cover member 11 of the embodiments shown in Figs. 1 to 4B. - As shown, the cover body 32 is formed with an oil filler neck 34 whose opening is closed by an oil filler cap 36. The cover body 32 is further formed with a blow-by gas passage neck 38 to which a blow-by gas passage tube 40 is inserted. The reference numeral 42 denotes a buffle plate which is attached to the cover body 32, for example, with adhesive. The bottom edge of the cover body 32 is securely inserted into the groove 44a of a retainer member 44 which is secured to the top surface of a cylinder head (not shown) by means of bolts inserted into openings 48 of the retainer member. An elastic or elastomeric member 50 made of a material such as rubber or the like is interposed between the bottom edge surface of the cover body 32 and the surface of the groove 44a.
While only the engine side covers and the rocker covers have been shown and described as the embodiments of the present invention, it will be understood that the present invention may be applied to other covers to be vibrated.
As appreciated from the above, according to the present invention, as the vibration from a vibrating member is absorbed by the elastic member disposed within the retainer member, the vibration transmission to the plate-like cover member can be grealy suppressed. In addition to this vibration suppression effect, by a noise suppression effect due to the high damping capacity material constituting the plate-like cover member, noise emission from the cover member is extremely reduced. This can grealty lower the noise level due to the vibration of the cover member, thereby extremely contributing to total engine noise reduction.

Claims

1. A noise reducing cover (10) comprising:

a retainer member (24) secured to a structural member (12) capable of being vibrated and formed with a groove (24b);

a cover member (11) whose major part (22) is made of a material which is high in damping capacity, said cover member being formed with an edge section (11a) which is disposed within said groove of said retainer member; and

an elastic member (28) disposed between the surface of said· groove and the surface of the edge section of said cover member.

- (Figs. 1(2),3A(3B), 4A(4B), 5)

2. A noise reducing cover as claimed in Claim 1, wherein said cover member (11) is of the shape of a plate and includes a first layer (20) made of a material which has an oil and water-proof ability, said first layer being contactable with at least oil, and a second layer (22) made of a material which is high in damping capacity, said second layer being securely attached to said first layer and larger in volume than said first layer. (Figs. 1(2),3A(3B), & 4A(4B))

3. A noise reducing cover as claimed in Claim 1, wherein said structural member to which said retainer member is secured is an engine body (12), in which said retainer member is securely attached to an attachment surface of the engine body, which attachment surface surrounds an exposed section (12a) of the engine body. (Figs. 1(2),3A(3B), & 4A(4B))

4. A noise reducing cover as claimed in Claim 1, wherein said retainer member (14) is formed with parallel first and second plate sections (P₁,P₂) between which said groove (24b) is defined, said second plate section (P₂) being located inside of said cover member (11). (Figs. 1(2),3A(3B), & 4A(4B))

5. A noise reducing cover as claimed in Claim 1, wherein said retainer member (14) is made of a material selected from the group consisting of rigid plastic, and metal. (Figs. 1(2),3A(3B), & 4A(4B))

6. A noise reducing cover as claimed in Claim 2, wherein said first layer (20) of said cover member (11) is made of a material selected from the group consisting of rubber, and plastic. (Figs. 1(2),3A(3B), & 4A(4B))

7. A noise reducing cover as claimed in Claim 2, wherein said second layer (22) of said cover member is made of one selected from the group consisting of a material containing plastic, a fibrous material, rubber, and foam metal. (Figs. 1(2),3A(3B), & 4A(4B))

8. A noise reducing cover as claimed in Claim 4, wherein said first plate section of said retainer member (24) is smaller in width than said first second section (^P ₂). (Figs. 3A(3B))

9. A noise reducing cover as claimed in Claim 4, wherein said first and second plate sections (P₁, P₂) are perpendicular to an attachment surface (B) through which said retainer member is attached to said structural member, so that said groove (24b) is perpendicular to the attachment surface (B) of said retainer member. (Fig. 4A(4B))