JP2660816B2 - Scarf - Google Patents

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 attached to a small engine (also referred to as a general-purpose engine) for driving a brush cutter, a generator and the like.

[0002]

2. Description of the Related Art A muffler of this type is generally divided into a muffler main body 21 and a lid 22 thereof as shown in FIG. The muffler body 21 and the lid 22 are formed by die casting of an aluminum alloy or by sheet metal. In addition, since the muffler is formed of a metal material in this manner, the muffler surface becomes hot to a temperature close to the temperature of the exhaust gas (400 ° C. or higher). Therefore, a muffler cover 23 made of resin is provided to cover the periphery of the muffler. The muffler cover 23 is provided separately from the muffler lid 22 in order to avoid direct transmission of heat. In the drawing, reference numeral 26 denotes a stay, and 27 denotes a mounting screw (bolt).

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

[0004]

The above-mentioned conventional muffler has the following disadvantages. That is, since the muffler cover 23 is separate from the lid 22 and a space for heat insulation is provided between the muffler cover 23 and the lid 22, the muffler cover 23 has a muffler main body (the muffler main body 21 and the lid 22), which is much larger than that of 22), and hinders the size and weight of the general-purpose engine as a whole.

The muffler cover 23 is separate from the lid 22, and the lid 22 is attached to and joined to the muffler body 21. However, apart from the attachment of the lid 22, it is necessary to attach a muffler cover 32. Therefore, it takes time to assemble. Naturally, it takes time to disassemble.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the conventional muffler, and to provide a muffler which does not require assembling and disassembling, is easy to handle, and can be reduced in size and weight. .

[0007]

In order to achieve the above object, the muffler of the present invention is divided into a) a muffler body attached to an engine side, a lid plate joined to the muffler body, and a muffler cover. In the muffler, b)
The muffler cover is formed of a thermosetting resin, and a large number of ribs are integrally protruded from the surface of the muffler resin.c) The cover plate is formed of sheet metal, and the cover plate is formed on the inner surface of the muffler cover. muffler is interposed insulation layer integrally attached to the inner surface of the muffler cover, thus integrated between the
-Attach the cover and lid plate to the muffler body on the engine side.
It is designed to be removable .

According to a second aspect of the present invention, there is provided a muffler divided into a) a muffler main body attached to the engine side, a lid plate joined to the muffler main body, and a muffler cover, and b) thermosetting the muffler cover. A plurality of ribs are integrally formed on the surface of the muffler cover, and a plurality of mounting screw holes are formed in the muffler cover, and a collar is formed in each hole. A part of the muffler cover is fitted so as to slightly protrude from the inner surface of the muffler cover, and e) the cover plate is formed of a sheet metal.
-A heat insulating material layer is interposed between the cover and the cover.
A plate is brought into contact with the protruding end of each of the collars,
Tighten the muffler cover to the main body with the mounting screw
By fixing, a slight gap is provided between the inner surface of the muffler cover and the cover plate, and the inner surface of the muffler cover is provided.
The cover plate can be integrally mounted .

According to a third aspect of the present invention, f) the lid plate is formed in a rectangular shape, and two locking pieces are extended outwardly from one edge thereof at an interval, and the center of the opposite edge is formed. A support piece having a mounting hole in the portion is extended outward, and g) a locking hole corresponding to each of the locking pieces is provided on the inner surface side of the muffler cover, and the mounting piece corresponds to the mounting hole of the support piece. H) each locking piece of the lid plate is loosely inserted into the locking hole of the muffler cover, and the mounting hole of the support piece of the lid plate is fitted into the projection of the muffler cover. It may be fixed with a back-type washer.

[0010] As described in claim 4, i) the thermosetting resin is more preferably a phenol resin impregnated with glass fibers.

According to a fifth aspect of the present invention, j) the height of the ribs can be changed alternately or every several ribs.

[0012]

According to the muffler of the present invention having the above-mentioned structure, the muffler cover is attached to the muffler body in a state where the muffler body is attached to the engine in advance and the muffler cover is attached to the muffler body in a state where the muffler cover is integrated with the cover plate. Is always handled in an integrated state (except during cleaning). Therefore, the attachment or detachment of the cover plate and the muffler cover are completed in one operation, respectively, and the cover plate (cover) and the muffler cover have to be completely separately attached to the conventional muffler which must be separately attached. In comparison, the work is simpler and the work time is reduced. Also,
From the manufacturing point of view, the number of parts such as screws for attaching the muffler cover to the lid plate (lid body) is reduced, making assembly and disassembly easy, maintenance and management easier, and manufacturing costs reduced. You.

Functionally, high-temperature exhaust gas passes through the space between the muffler body and the cover plate, but is insulated by the heat insulating material layer of c), and the heat of the exhaust gas is not directly transmitted to the muffler cover. The temperature of the lid plate is quite high (near the exhaust gas temperature), but the surface of the muffler cover has many heat-dissipating ribs, so the temperature drops at the tip of the ribs. Since it is formed of a conductive resin and has a function of reinforcing a large number of ribs, it is superior to the above-described conventional muffler because it does not deform due to heat.

Further, since the muffler cover and the cover plate are integrally mounted, there is almost no gap (space) between the cover plate (cover) and the muffler cover. The overall volume is reduced compared to the muffler. As a result, the volume of the protruding portion from the engine is reduced, the size and weight are reduced, and the appearance is improved.

In the end, the muffler of the present invention has a conventional muffler structure in which the muffler cover and the lid are completely separate from each other, and the lid is formed on a (thin plate-shaped) lid plate, and is integrally formed with the muffler cover. Incorporation into the system makes it possible to handle it as a single part (muffler cover or lid), which facilitates assembly and disassembly operations, and also makes it easier to reduce the size and weight of the muffler itself. In addition, the function as a muffler is not inferior to that of the conventional muffler, and is rather excellent.

According to the muffler of the second aspect, the cover plate is pressed against the muffler main body via the plurality of collars by firmly fixing the muffler cover to the muffler main body with mounting screws such as bolts. While being joined, the muffler cover is also firmly fixed to the muffler body via a plurality of mounting screws. The lid plate abuts the protruding ends of the collars and is supported slightly above the inner surface of the muffler cover, so a small gap between the inner surface of the muffler cover and the lid plate is uniform over almost the entire surface. Formed. For this reason, the temperature of the cover plate that comes into contact with the exhaust gas becomes high, but only a part of the heat of the cover plate is transmitted to the muffler cover via the plurality of collars, and the temperature of the muffler cover does not increase significantly. Therefore, heat deterioration of the muffler cover hardly occurs, and durability is improved.

According to the third aspect of the muffler, in a state where the two locking pieces of the cover plate are loosely inserted into the locking holes of the muffler cover, the lid plate faces each other with the two locking pieces as fulcrums. The cover plate can be integrally attached to the muffler cover by fitting the mounting hole of the support piece on the side into the projection of the muffler cover and fitting a springback type washer to the projection. On the other hand, after removing the spring-back type washer from the projection of the muffler cover, the opposite side of the lid plate is pulled up from the muffler cover with the two locking pieces of the lid plate as fulcrums, so that the support piece (the mounting hole) is formed. Is removed from the projection of the muffler cover, the cover plate is pulled out to one side of the support, and two locking pieces are removed from the locking holes of the muffler cover, whereby the cover plate can be removed from the muffler cover.

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

According to the muffler according to the fifth aspect, when a hand or the like comes into contact with the muffler, the muffler only comes into contact with the rib having a high peak.
The contact range (contact area) is narrow.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a muffler according to the present invention will be described below with reference to the drawings.

FIG. 1 is a front view schematically showing a two-cycle general-purpose engine provided with a muffler (shown in cross section) according to an embodiment of the present invention. FIG. 2 is a front view showing one embodiment of a muffler cover. 3 is a rear view of the muffler cover of FIG. 2, FIG. 4 is a left side view of the muffler cover of FIG. 2, FIG. 5 is a plan view of the muffler cover of FIG. 2, FIG. 7 is a right side view of the cover plate of FIG. 6, FIG. 8 is a front view showing an example of the gasket, and FIG. 9 (a) is a central longitudinal sectional view showing a state where the cover plate is integrated into the inner surface of the muffler cover. FIG. 9B is a front view of the springback type washer.

As shown in FIG. 1, a recoil starter (not shown) provided with an operation knob 2 is provided on the back of the center of the engine 1. Muffler 1 on the right side of Engine 1
0 is provided. A carburetor 4 is disposed on the left side of the engine 1, and an air cleaner 5 is connected to the carburetor 4. A fuel tank 3 is fixed to a lower surface of the engine 1.

The muffler 10 is a metal muffler body 11 formed by die-casting aluminum or sheet metal.
And a metal lid plate 12 and a synthetic resin muffler cover 13
The muffler body 11 is attached to the engine 1 with the attachment screws 7.

The cover plate 12 is made of a thin steel plate made of sheet metal, is formed so as to correspond to the inner surface unevenness of the muffler cover 13, and is integrally incorporated into the inner surface side of the muffler cover 13 as if it were a conventional cover. The body also serves as a muffler cover. As shown in FIGS. 6 and 7, the cover plate 12 is formed in a substantially square shape, a recess 12 a having a large central portion depressed to one side, and a peripheral portion 12 b of the recess 12 a is formed in a flat shape. An inward frame portion 12c is formed. A screw hole 12d is opened in the peripheral portion 12b at a position corresponding to a screw hole 14a described later. Frame part 12
c on one edge, two locking pieces 12e spaced apart in the width direction.
Are protruded outwardly, and a support piece 12f is protruded outwardly at the center of the opposing edge, and a mounting hole 12g is formed in the support piece 12f. Further, a part of the recess 12a is further depressed to one side as shown in FIG. 7, and is opened laterally to fix the exhaust cylinder 12h (FIG. 6).

In this embodiment, the muffler cover 13 is
It is integrally molded with phenol resin impregnated with glass fiber. In the case of the present example, a molding method is employed in which the SMC, that is, a plate-like phenolic resin material having a constant thickness is heated and molded at the same time as being pressed by a mold. Thermosetting resins include urea resins and melamine resins in addition to phenolic resins. However, the heat deformation temperature is high (250 ° C
As described above, and because the bending strength is large (14 kgf / mm ² ), a phenol resin containing glass fiber (glass content 30% in this example) is desirable.

As shown in FIGS. 2 to 5, the muffler cover 13 is a conventional lid 22 having a substantially square shape with one surface opened.
A box-shaped portion 13a corresponding to FIG.
and a skirt portion 13b extending slightly from the peripheral edge in the opening direction. On the surface of the box-shaped portion 13a, ribs (also referred to as fins) 13c extending in the lateral direction are protruded at regular intervals as shown in FIG. 2, and screw holes (4) of mounting screws 15 (FIG. 1) are provided. (A location) 14a penetrates and a recess 14 is provided in which the head 15a of the screw 15 is housed,
Around the recess 14, a cylindrical peripheral wall 14b protrudes so that the head 15a of the screw 15 does not protrude outward. The amount of protrusion (height) of the rib 13c is set to 5 mm or more so that a temperature drop is sufficiently generated so that the tip of the rib is not hot even if touched by a hand. As shown in FIG. 1, FIG. 4, FIG. 5, etc., the height of the ridge of the rib 13c is changed alternately, or is changed every few ribs. The rib 13c is provided continuously up to the skirt portion 13b. Further, one end of the box-shaped portion 13a of the muffler cover 13 has an exhaust hole 1 as shown in FIG.
6 is opened laterally in parallel with the rib 13c.

Also, on the inner surface of the skirt portion 13b,
As shown in FIG. 3, locking holes 13d corresponding to the two locking pieces 12e (FIG. 6) of the cover plate 12 are provided on one inner wall surface so as to protrude inward. A bar-shaped projection 13e is provided at a position corresponding to the mounting hole 12g of the support piece 12f (FIG. 6) on the side facing the locking hole 13d. In the vicinity of the center of one side edge of the cover plate 12, as shown in FIG.
The tongue piece 12i is provided to insert the tip of the driver when the cover plate 12 is separated from the muffler main body 11. When the cover plate 12 is joined to the muffler body 11 together with the muffler cover 13, an adhesive liquid gasket (not shown) is applied to the joining surface, so that the cover plate 12 can be easily separated from the muffler body 11. There are times when there is no such thing.

Here, the structure for assembling the cover plate 12 into the muffler cover 13 will be described in detail.

As shown in FIG. 9A, the muffler cover 1
3 is fitted on the inner peripheral surface of each screw hole 14a. One end of each of the collars 17 is slightly (0.5 mm to 1 mm) from the inner surface of the muffler cover 13.
Degree) projecting. This causes a small gap between the cover plate 12 and the cover plate 12 when the cover plate 12 is mounted on the inner surface of the muffler cover 13, and prevents the cover plate 12 from contacting the inner surface of the muffler cover 13. This is to prevent the heat of the plate 12 from being directly transmitted to the muffler cover 13. In addition, a heat insulating material layer 18 also serving as a sound absorbing material is attached to almost the entire surface of the concave portion in the box-shaped portion 13a of the muffler cover 13. In the present embodiment, the heat insulating material layer 18 is formed by pressing ceramic fibers having a thickness of about 10 mm according to the inner shape of the concave portion of the box-shaped portion 13a. In particular, the exhaust gas outlet (not shown) of the muffler body 11 faces the cover plate 12 and the high-temperature exhaust gas hits the inner surface of the cover plate 12, but since the heat insulating material layer 18 is lined, the muffler cover 1
3 is not intensively heated by the exhaust gas impinging on the cover plate 12. Although not shown, the muffler body 11
A sound-absorbing and heat-insulating material is also attached to the inner surface of the.

Further, on the inner surface of the muffler cover 13, a substantially rectangular frame-shaped asbestos gasket 19 for heat insulation as shown in FIG. 8 is attached on the peripheral portion of the box-shaped portion 13 a, and the cover plate 12 is disposed thereon. . The gasket 19 has the collar 1
7 are opened, and those holes 1a are opened.
The collar 17 protrudes from 9a. The thickness of the gasket 19 is 0.5 mm to 1 m depending on the amount of protrusion of the collar 17.
m.

The locking hole 13 of the muffler cover 13
d, the two locking pieces 12e of the lid plate 12 are loosely inserted, and in this state, the mounting holes 12g of the support pieces 12f on the opposite side of the lid plate 12 are projected with the two locking pieces 12e as fulcrums. Fit into the part 13e. Then, a spring-back washer 20 shown in FIG.
The cover plate 12 is attached to the muffler cover 13
It is attached integrally to. The washer 20 has a large number of cuts 20b radially formed around a hole 20a having a diameter slightly smaller than the outer diameter of the protrusion 13e.
Once fitted into 3e, it does not come off easily.

In this manner, the cover plate 12 is integrally attached to the inner surface of the muffler cover 13. For example, when disassembling at the time of inspection or cleaning, the washer 20 is projected using a tool. After being removed from the end of the portion 13e, the mounting hole 12g of the opposing support piece 12f is fitted to the projection 13 using the two locking pieces 12e of the cover plate 12 as a fulcrum.
e, the cover plate 12 can be removed.

By the way, the muffler cover 13 integrated with the cover plate 12 is provided with the muffler body 11 in the following procedure.
Easy to install. That is, as shown in FIG. 1, a liquid gasket (not shown) is applied to a joint surface with a cover plate 12 on a muffler main body 11 previously attached to the engine 1 with a stay 6 and an attachment screw 7, and then the muffler The cover 13 has four bolts (mounting screws) 15
(FIG. 1) to be attached by tightening respectively. In this state, the cover plate 12 has four collars 17.
The cover plate 12 is pressed against and joined to the muffler body 11 through the
It is pressed to one side, and a gap is formed almost entirely over the inner surface of the muffler cover 13. That is, the cover plate 12 is supported by being pressed against the muffler main body 11 by the four collars 17, and a slight gap is formed between the cover plate 12 and the inner surface of the muffler cover 13. The locking hole 13d of the muffler cover 13 is formed slightly larger than each locking piece 12e of the cover plate 12, and the mounting hole 12g of the support piece 12f is formed larger than the outer diameter of the projection 13e. Further, the washer 20 is supported by the support piece 12 of the lid plate 12 at the end of the projection 13e.
f, so that the locking piece 12e of the cover plate 12 floats in the locking hole 13d, and the mounting hole 12g of the support piece 12f also floats from the projection 13e. The cover plate 12 is integrally attached to the muffler cover 13 in a non-contact state except for contact with the collar 17.

Then, as shown in FIG.
A gasket 19 is interposed in a part of a gap between the gasket 19 and the inner surface of the muffler cover 13, and a heat insulating material layer 18 is interposed in another part. For this reason, the temperature of the cover plate 12 which comes into direct contact with the exhaust gas is considerably high, but only a part of the heat is transmitted to the muffler cover 13 through the four collars 17, and the temperature of the muffler cover 13 is reduced. Does not rise significantly. Moreover, a rib 13c protruding 5 mm or more is provided on the surface of the muffler cover 13, and a considerable temperature drop occurs at the tip of the rib 13c. Also, the muffler cover 13
Since the bolts 15 (FIG. 1) are fixed to and supported by the muffler main body 11, the bolts 15 (FIG. 1) are not easily loosened by the vibration of the engine 1 or the muffler cover 13 is not detached.

Although the embodiment of the muffler of the present invention has been described above, the present invention can be implemented as follows.

The direction of the rib 13c may be vertical, oblique, or may cross the rib vertically and horizontally.

As the heat insulating material layer 18, asbestos or the like can be used in addition to glass wool.

As long as the material of the muffler cover 13 is a thermosetting resin, the material is not limited to a phenol resin containing glass fibers, and for example, a phenol resin urea resin without glass fibers or a melamine resin may be used.

Instead of the springback type washer 20, the support piece 12 f may be prevented from coming off using, for example, a nut that is screwed to the end of the protrusion 13 e. In this case, the nut contacts the support piece 12 f. Fasten not to.

[0040]

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

(1) In the conventional muffler structure in which the muffler cover and the lid are completely separate, the lid (cover plate) is integrated into the muffler cover, and substantially one part (the muffler cover or the lid) is formed. By enabling handling as (1), work such as assembling and disassembly becomes easy, and it is superior in function to the conventional muffler.

(2) Since the overall volume is reduced as compared with the conventional muffler with a muffler cover, the amount of protrusion from the engine is suppressed, so that the size and weight can be reduced, and the design can be expanded. , Appearance is also good.

(3) Since the thermal conductivity of the muffler cover itself is low and the ribs are protruded, the temperature of the surface (the tip of the rib) is so low that it is not hot even if touched by hand, and reinforcement by the ribs Almost no deformation due to heat occurs.

According to the second aspect of the muffler, (4) the cover plate is pressed against the muffler body via a plurality of collars and fixedly joined to the muffler body by tightening the muffler cover with mounting screws. In addition, the muffler cover is also firmly fixed to the muffler body via a plurality of mounting screws.

(5) The cover plate is supported by the protruding ends of the plurality of collars, and a gap is provided over substantially the entire surface between the inner surface of the muffler cover and the cover plate. Only a part of the heat of the plate is transmitted, and the temperature of the muffler cover does not rise so much that heat deterioration of the muffler cover hardly occurs and durability is improved.

According to the third aspect of the muffler, (6) the operations of integrally attaching and disassembling the cover plate to the muffler cover can be performed easily and reliably in a short time.

(7) Since the muffler cover is formed of a phenolic resin containing glass fibers, the heat resistance and strength are further improved, and the surface temperature is further lowered.

(8) Even if a hand or the like comes into contact with the muffler cover,
The contact area (contact area) is very narrow without contacting the entire surface of the rib.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a two-cycle general-purpose engine provided with a muffler (shown in cross section) according to an embodiment of the present invention.

FIG. 2 is a front view showing one embodiment of a muffler cover.

FIG. 3 is a rear view of the muffler cover shown in FIG. 2;

FIG. 4 is a left side view of the muffler cover of FIG. 2;

FIG. 5 is a plan view of the muffler cover of FIG. 2;

FIG. 6 is a rear view showing an embodiment of a cover plate.

FIG. 7 is a right side view of the lid plate of FIG. 6;

FIG. 8 is a front view showing an example of a gasket.

FIG. 9A is a central vertical sectional view showing a state in which a cover plate is integrally incorporated into an inner surface of a muffler cover, and FIG. 9B is a front view of a springback type washer.

FIG. 10 is a side view showing a conventional general-purpose engine muffler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 10 Muffler 11 Muffler main body 12 Cover plate 12e Locking piece 12f Supporting piece 12g Mounting hole 13 Muffler cover 13a Box-shaped portion 13c Rib 13d Locking hole 13e Projection 17 Color 18 Heat insulation material layer 19 Gasket 20 Spring back type washer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-64615 (JP, A)

Claims (5)

(57) [Claims] 1. A muffler divided into a muffler main body attached to an engine side, a cover plate joined to the muffler main body, and a muffler cover, wherein the muffler cover is formed of a thermosetting resin, and a plurality of muffler covers are formed on the surface thereof. The ribs of the muffler cover are integrally formed on the inner surface of the muffler cover by interposing a heat insulating material layer between the lid plate and the inner surface of the muffler cover. Muffler cover attached and thus integrated
And the cover plate can be attached to and detached from the muffler body on the engine side.
A muffler characterized by being attached to the muffler. 2. A muffler book attached to an engine side.
The cover plate and muffler cover that are joined to the body and this muffler body
And the muffler cover is formed of a thermosetting resin.
In addition, a large number of ribs are integrally projected on the surface with thermosetting resin
A plurality of mounting screw holes are drilled in the muffler cover, and a collar is fitted in each hole with a part thereof slightly projecting from the inner surface of the muffler cover, and the lid plate is formed of sheet metal. The cover plate and the muffler cover
With a heat insulating material layer between
Abut on the protruding end of each collar, and
Secure the muffler cover to the body with the mounting screw
By providing a slight gap between the inner surface of the muffler cover and the lid plate,
A muffler characterized by a plate attached integrally . 3. The support plate is formed in a square shape, and two locking pieces are extended outward from one edge thereof at an interval, and a support piece having a mounting hole at a center portion of the opposite edge is provided. Extending outward, on the inner surface side of the muffler cover, a locking hole corresponding to each locking piece is provided, and a projection corresponding to a mounting hole of the support piece is provided, and each of the lid plates is provided. 3. The locking piece is loosely inserted into a locking hole of the muffler cover, and a mounting hole of a support piece of the cover plate is fitted into a projection of the muffler cover and fixed with a springback type washer. The muffler described. 4. The muffler according to claim 1, wherein the thermosetting resin is a phenol resin impregnated with glass fibers. 5. The muffler according to claim 1, wherein the heights of the ribs are changed alternately or every several ribs.