JPH07269340A - Muffler - Google Patents

Abstract

PURPOSE:To provide a muffler which reduces the number of parts, facilitates assembling, and is compact and light weight. CONSTITUTION:It is a muffler which is divided into a muffler main body 11 to be mounted on an engine 1 side and its lid 12. The lid 12 is made of thermosetting resin and molded integrally in a shape which also serves as a muffler cover. Many ribs 12c made of thermosetting resin are provided integrally on a surface of the lid 12 in such a way that they protrude. A layer of heat- resistant thermal insulation material made of ceramics is provided on an inner face of the lid 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a muffler which is attached to a small engine (also called a general-purpose engine) mainly for driving a brush cutter, a generator and the like.

[0002]

2. Description of the Related Art Generally, a muffler of this type is divided into a muffler body 21 and a lid 22 thereof as shown in FIG. 3, and the muffler body 21 is attached to an engine 1. The muffler main body 21 and the lid 22 are die cast from an aluminum alloy or sheet metal. Further, since the muffler is formed of the metal material in this way, the surface of the muffler becomes hot up to the temperature of the exhaust gas (400 ° C. or higher). The muffler cover 23 is provided separately from the muffler cover 22 in order to avoid direct heat transfer.

A muffler having such a structure is described in, for example, Japanese Utility Model Laid-Open No. 62-184124 and Japanese Utility Model Laid-Open No. 4-89819.

[0004]

The muffler of the conventional structure described above has the following disadvantages. That is, since the muffler cover is considerably larger than the muffler, it hinders the reduction in size and weight of a general-purpose engine.

Since the muffler cover is separate from the lid body, the number of parts is increased, and it is necessary to attach the muffler cover separately from the attachment of the lid body, which requires time and effort for assembly. Needless to say, disassembling also takes time.

An object of the present invention is to solve the above-mentioned inconveniences in the conventional muffler, and to provide a muffler which has a small number of parts, is easy to assemble, and can be reduced in size and weight.

[0007]

In order to achieve the above object, the muffler of the present invention is a) a muffler divided into a muffler body attached to the engine side and a lid body thereof, and b) the lid body. A thermosetting resin is integrally molded into a shape that also serves as a muffler cover, and a large number of ribs are integrally formed on the surface of the lid by a thermosetting resin, and c) ceramics and glass wool are formed on the inner surface of the lid. It is equipped with a heat resistant heat insulating material layer such as.

As described in claim 2, d) the lid is
Molded into a shape with a box-shaped part having a substantially square-shaped opening with one surface and a skirt part extending slightly from the periphery of the box-shaped part in the opening direction. The opening can be provided.

More preferably, the e) or the thermosetting resin is a glass fiber-impregnated phenolic resin.

[0010]

According to the muffler of the present invention having the above-mentioned structure, the lid (including the muffler cover) is attached to the muffler body in a state where the muffler body is attached to the engine in advance. Therefore, installation or removal of the lid and muffler cover is completed in one operation, which is easier and requires less time than the conventional muffler in which the lid and muffler cover are separate entities. To be done. Also, from the manufacturing perspective, the number of parts is reduced (several points if the muffler cover mounting screws are included).
As a result, it is easy to assemble, maintenance is easy, and manufacturing costs are reduced.

Functionally, high-temperature exhaust gas passes through the muffler, but it is insulated by the heat-resistant heat-insulating material layer of c) above, heat of the exhaust gas is not directly transmitted to the lid, and the inner surface of the lid is The temperature on the side is much higher (lower than the exhaust gas temperature, 220
However, since the ribs have many ribs on the surface, the temperature drops at the tip of the ribs and the inner surface of the lid becomes quite hot, but it is made of thermosetting resin. Further, since many ribs have a function of reinforcing the lid, they are superior to the above-described muffler having the conventional structure because of no deformation due to heat.

By integrating the muffler cover with the lid, the entire volume is reduced as compared with the conventional muffler with a muffler cover (see the virtual line display in FIG. 3). As a result, the protruding portion from the engine is reduced, the size and weight are reduced, and the appearance is improved.

According to the muffler of the second aspect, the skirt portion functions as a conventional muffler cover, and prevents the skirt portion from touching the high temperature metal muffler body with a hand or the like. Further, the heat of the inside (especially the muffler body) is radiated from the opening of the skirt portion, and the temperature rise in the skirt portion is prevented.

According to the muffler of the third aspect, since the lid is formed of the phenol resin impregnated with the glass fiber, the heat resistance and strength are further improved, and the thermal conductivity of the resin itself is low. The surface temperature of the lid further drops.

[0015]

Embodiments of the muffler of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a two-cycle general-purpose engine equipped with a muffler of the present invention, FIG. 2 shows an embodiment of a lid body integrated with a muffler cover, and FIG. 2 (a) is a front view.
2B is a rear view and FIG. 2C is a sectional view taken along the line CC of FIG.

As shown in FIG. 1, a recoil starter (not shown) having an operation knob 2 at its upper end is provided on the rear surface of the center of the engine 1. A muffler 10 is arranged on the right side of the engine 1. On the left side of the engine 1,
A carburetor 4 is provided, and an air cleaner 5 is connected to the carburetor 4. On the bottom of the engine 1,
The fuel tank 3 is fixed.

The muffler 10 is divided into a metal muffler main body 11 and a lid 12 which are made of aluminum die cast, and the muffler main body 11 is attached to the engine 1 with screws.

The lid 12 is integrally formed with a conventional muffler cover, in other words, also serves as a muffler cover. In this example, it is integrally molded with a phenol resin impregnated with glass fiber. In the case of this example, as a molding method, SMC, that is, a method in which a plate-shaped phenol resin material having a constant thickness is pressed by a mold and simultaneously heated is molded. The thermosetting resin includes urea resin, melamine resin, etc. in addition to phenol resin. However, the heat distortion temperature is high (250 ° C or higher) and the bending strength is high (1
Since it is 4 kgf / mm ² , the glass fiber-containing phenolic resin (in this example, the glass content rate is 30%) is desirable. The lid body 12 is a conventional lid body 2 having a substantially square shape with one surface opened.
2 (FIG. 3) corresponding to the box-shaped portion 12a, and the box-shaped portion 12
The skirt portion 12b is provided so as to extend slightly from the peripheral edge of a in the opening direction.

On the surface of the box-shaped portion 12a, ribs (also referred to as fins) 12c extending in the lateral direction are provided at regular intervals as shown in FIG. 2 (a), and screw holes (4 14a is provided therethrough, and a recess 14 for accommodating the head 13a of the screw 13 is provided, and the screw 1 is provided around the recess 14.
A cylindrical peripheral wall 14b is provided so as to project so that the head portion 13a of No. 3 does not project outward. In addition, the protrusion amount (height) of the rib 12c is set to 5 mm or more so that the temperature drop sufficiently occurs so that the rib tip is not hot even if it is touched by the hand. A large number of elongated holes 12d are opened at intervals in the skirt portion 12b so that the heat of the muffler body 11 is dissipated. Reference numeral 14 '(Fig. 2 (c)) is a shallower recess than the others,
Although the head 13a of the screw 13 projects, there is no problem because it is not a place to touch with the upper part of the lid 12. Further, an exhaust pipe 12e is integrally formed on the inner surface of the lid body 12 as shown in FIGS. 2B and 2C, and one end is opened to the outside as shown in FIG. 2A.

On the inner surface of the box-shaped portion 12a of the lid body 12,
The heat insulating material layer 15 (FIG. 2 (c)), which also serves as a sound absorbing material, is attached over almost the entire surface, and when the peripheral edge portion of the box-shaped portion 12a of the lid 12 is abutted against the peripheral edge portion of the muffler body 11, the It is attached by being sandwiched at the peripheral edge. In this example, as the heat insulating material layer 15, a ceramic fiber having a thickness of about 10 mm is soaked in a phenol resin solution and then hot pressed according to the inner surface shape of the box-shaped portion 12a. Particularly, the exhaust gas outlet (not shown) of the muffler body 11 faces the lid body 12, and the hot exhaust gas is fed to the lid body 1.
Although it corresponds to the inner surface of 2, the heat insulating material layer 15 is lined, so that part of the lid 12 is not heated by the exhaust gas. Although not shown, the sound absorbing and heat insulating layer material is also attached to the inner surface of the muffler body 11.

The muffler 10 according to this embodiment is constructed as described above. Engine 1 of this muffler 10
As shown in FIG. 1, first, the muffler main body 11 is attached to the engine 1 via the stay 16 and the set screw 17, and then the heat insulating material layer 15 is attached to the lid 1.
It is simply finished by covering the muffler main body 11 with it attached to the inner surface of 2 and fixing it with a plurality of screws 13.

Although one embodiment of the muffler of the present invention has been described above, it can be carried out as follows.

The direction of the rib 12c may be a vertical direction, an oblique direction, or vertical and horizontal ribs may intersect.

As the heat insulating material layer 15, asbestos or the like can be used in addition to glass wool.

[0026]

As is apparent from the above description,
The muffler of the present invention has the following effects.

(1) The muffler cover, which is a separate body in the past, is integrated with the lid body, and the exhaust pipe and the like are formed separately with a sheet metal lid body and attached by welding or the like. Since all can be integrally molded with resin, the number of parts is considerably reduced, assembly and disassembly are easy, working time is shortened, maintenance is easy, and manufacturing cost is reduced.

(2) Compared with the conventional muffler with a muffler cover, the overall volume is reduced, so that the amount of protrusion from the engine is suppressed, the size and weight are reduced, and the design range is widened. , The appearance will be good.

(3) Because of the heat insulation of the heat resistant heat insulating material layer, the thermal conductivity of the lid itself is low, and the ribs are projected,
The temperature of the lid surface (tip of the rib) is so low that it will not be hot to the touch, and the reinforcing effect of the rib hardly causes deformation due to heat.

According to the muffler of claim 2, (4) the skirt prevents the skirt from touching the main body of the high-temperature metal muffler with a hand or the like, and heat is radiated from the opening of the skirt, so that the inside of the skirt Temperature rise is prevented.

According to the muffler of claim 3, (5) since the lid is made of the glass fiber-containing phenol resin, the heat resistance and strength are further improved, and the surface temperature of the lid is further lowered.

[Brief description of drawings]

FIG. 1 is a front view showing a two-cycle general-purpose engine equipped with a muffler according to an embodiment of the present invention.

2A and 2B show an embodiment of a lid body in which a muffler cover is integrated, FIG. 2A is a front view, FIG. 2B is a rear view, and FIG.
2 is a sectional view taken along the line CC of FIG.

FIG. 3 is a side view showing a conventional general muffler for a general-purpose engine.

[Explanation of symbols]

 1 Engine 10 Muffler 11 Muffler Main Body 11 12 Lid 12a Box 12b Skirt 12c Rib 12d Slot 12e Exhaust Cylinder 13 Screw 14 Recess 15 Heat Insulation Layer 16 Stay 17 Set Screw

Claims (3)

[Claims] 1. A muffler divided into a muffler main body attached to an engine side and a lid thereof, wherein the lid is integrally molded with a thermosetting resin so as to also serve as a muffler cover, and A muffler characterized in that a large number of ribs are integrally projected on the surface with a thermosetting resin, and a heat resistant heat insulating material layer such as ceramics or glass wool is attached to the inner surface of the lid. 2. The lid body is formed into a form including a box-shaped portion having a substantially rectangular shape with one surface opened, and a skirt portion extending from the periphery of the box-shaped portion so as to slightly expand in the opening direction. ,
The muffler according to claim 1, wherein the skirt portion is provided with a large number of openings at intervals. 3. The muffler according to claim 1, wherein the thermosetting resin is a phenol resin impregnated with glass fiber.