JP3005104U - Small engine muffler - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a muffler for a small engine that prevents oxidation and damage of a protective pipe for preventing the scattering of heat insulating materials and can be used stably for a long period of time. [Structure] One end of a protective pipe 15 attached around a heat insulating material 12 covering the tightening pipe 11 is brought into contact with the protective plate 8, and the other end is inside an opening 8a formed in the right protective plate 8. Is loosely inserted into the wall surface 1a of the muffler body 1 and is brought into contact therewith. Then, the wall surface 1a and the protective pipe 1 that is in contact with the wall surface 1a
A continuous fillet weld 16 is applied over the entire circumference at the corner of the edge of the protective pipe 15 at one end, and one end of the protective pipe 15 is fixed to the wall surface 1a.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention mainly relates to a muffler of a small engine (also called a general-purpose engine) used as a drive source for a brush cutter, a generator, or the like.

[0002]

[Prior art]

 This type of muffler is disclosed in Japanese Utility Model Publication No. 5-457771. As shown in FIG. 4, this muffler penetrates a muffler main body 21 having a hollow expansion chamber, and a muffler tightening pipe 22 is attached to the muffler main body 21, and a pipe wall of the tightening pipe 22 is attached. The outer periphery is covered with a heat insulating material 23, a protection pipe 24 for preventing scattering is attached around the heat insulating material 23, and a tightening bolt 25 inserted through the tightening pipe 22 allows a body 26 side of the small engine to be installed. It has a structure to be fixed to. Then, by covering the outer circumference of the pipe wall of the tightening pipe 22 with the heat insulating material 23, thermal deformation of the tightening pipe 22 is prevented.

[0003]

[Problems to be solved by the device]

 However, the muffler described in the above publication also has room for improvement in the following points. That is, a protective pipe 24 for preventing scattering is attached around the heat insulating material 23, and both ends of the protective pipe 24 are attached to the inner wall surface of the muffler body 21 as shown in FIG. It is brought into contact with a protective plate 27 for preventing damage to the heat insulating material 28. Therefore, when the exhaust gas flowing in the muffler body 21 comes into direct contact with the outer peripheral surface of the protection pipe 24 and the heat of the exhaust gas heats the protection pipe 24, there is no escape area for the heat, and the protection pipe is protected. Since the temperature of the pipe 24 becomes high, the protective pipe 24 may be oxidized, deteriorate in a short period of time, and be thermally deformed.

When the protective pipe 24 is thermally deformed, the heat insulating material 23 scatters in the muffler body 21, or the scattered heat insulating material 23 is discharged together with the exhaust gas. Further, when the heat insulating material 23 scatters and the outer peripheral surface of the tightening pipe 22 is exposed, the tightening pipe 22 is also thermally deformed and is heated to the tightening bolt 25 because the tightening pipe 22 is heated directly. It causes looseness.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a muffler for a small engine that prevents oxidation and thermal deformation of a protective pipe for preventing scattering of a heat insulating material and can be used stably for a long period of time. Has an aim.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the muffler of the present invention comprises: a) a muffler main body having a hollow expansion chamber, a muffler tightening pipe attached to the muffler main body, and a surrounding of the tightening pipe. Of the small engine with a structure in which the protective pipe for preventing scattering is attached to the periphery of the heat insulating material, and is fixed to the main body side of the small engine with a tightening bolt inserted into the tightening pipe. In the muffler, b) at least one end of the protection pipe is brought into contact with the wall surface of the muffler body.

As described in claim 2, it is more preferable that c) an end portion of the protection pipe is formed as a flange and the flange is brought into contact with a wall surface of the muffler body.

As described in claim 3, it is preferable that d) continuous fillet welding is performed around a contact point between the protection pipe and the wall surface of the muffler body.

As described in claim 4, e) at least one locking piece is extended at one end of the protection pipe, and a slit into which the locking piece can be inserted is formed on the wall surface of the muffler body. , F) Insert the locking piece through the slit and perform fillet welding between the peripheral edge of the slit and the locking piece, g) Face the locking piece toward the head of the tightening bolt. It is more preferable to bend and engage the tip of the locking piece with the head of the tightening bolt.

As described in claim 5, h) an aluminum-plated steel pipe having no hole can be used for the protection pipe.

[0011]

[Action]

 According to the muffler of the present invention having the above-described configuration, when exhaust gas comes into contact with the protective pipe and the protective pipe is heated, the heat is conducted to the wall surface of the muffler body through the protective pipe. Since the outside of the wall surface of the muffler body is open to the atmosphere, heat will escape from the wall surface of the muffler body to the atmosphere. Therefore, the temperature rise of the protective pipe is suppressed considerably compared to the conventional muffler, the oxidation of the protective pipe is prevented, and it is less likely to be thermally deformed even after long-term use.

In the muffler according to claim 2, since the end portion of the protection pipe is a flange and the contact area with the wall surface of the muffler body is large, the heat of the protection pipe is quickly and efficiently applied to the wall surface of the muffler body. It will be transmitted and it will be easier to escape.

In the muffler according to the third aspect, contact between the end portion of the protective pipe and the wall surface of the muffler body is reliably and sufficiently achieved by the fillet welding, and the contact area is increased by the continuous fillet welding. Because of the larger size, the heat of the protective pipe can easily escape to the wall surface of the muffler body. Moreover, since the protection pipe is supported by the wall surface of the muffler body, the protection pipe is firmly supported as compared with the conventional muffler which is supported between the protection plates of the heat insulating material.

According to the muffler of claim 4, the contact piece between the end portion of the protective pipe and the wall surface of the muffler body is increased by the locking piece at one end of the protective pipe, so that the heat of the protective pipe is transferred to the muffler body. Not only can it easily escape to the wall surface of the tightening bolt, but the tip of the locking piece is engaged with the head of the tightening bolt, which prevents the tightening bolt from loosening due to rotation even when the muffler vibrates. . Moreover, since the protection pipe is supported by the wall surface of the muffler body, the support of the protection pipe is firmer than that of the conventional muffler.

In the muffler according to claim 5, since the protection pipe is made of an aluminum-plated steel pipe, the thermal conductivity is high, the temperature of the protection pipe is hard to rise, and the aluminum plating layer does not oxidize when it comes into contact with the exhaust gas. To prevent.

[0016]

【Example】

 An embodiment of a small engine muffler according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall sectional view showing a first embodiment of a muffler.

As shown in FIG. 1, the muffler main body 1 has a hollow interior and is configured as an expansion chamber 2, and the inside of the expansion chamber 2 is divided into two chambers by a partition wall 3. Reference numeral 4 in the drawing denotes an exhaust gas inflow pipe into the muffler body 1, 5 denotes an exhaust gas exhaust pipe from the muffler body 1, and 6 denotes an intermediate pipe communicating the partition wall 3. An insulating material 7 such as glass wool is attached to the inside of the wall surface 1a of the muffler body 1, and the insulating material 7 is covered with a protective plate 8 such as punching metal. To attach the muffler body 1 to a small engine (not shown), screw the tip side screw portion 10a of the tightening bolt 10 into the screw hole 9a formed in the exhaust flange 9 or the like as in the conventional muffler. Done by. The tightening bolt 10 is inserted into the tightening pipe 11, and the tightening pipe 11 penetrates the lower portion of the muffler main body 1 and is provided across the opposite left and right wall surfaces 1a and 1a. ing. Further, the outer peripheral surface of the tightening pipe 11 is covered with a heat insulating material 12 such as glass wool. Reference numeral 13 is a washer that is interposed between the head portion 10b of the tightening bolt 10 and the wall surface 1a, and 14 is a gasket that is interposed between the exhaust flange 9 and the wall surface 1a of the muffler body 1.

Although the above-mentioned structure is a conventionally known structure, the muffler of the present invention has the following characteristic structure. That is, one end (left end in the figure) of the protection pipe 15 attached around the heat insulating material 12 covering the tightening pipe 11 is brought into contact with the protection plate 8, but the other end (right end in the figure) is It is loosely inserted into the opening 8a formed in the right protective plate 8 and abuts against the wall surface 1a of the muffler body 1. Then, continuous fillet welding 16 is applied to the corner portion between the wall surface 1a and the peripheral edge of one end of the protection pipe 15 that is in contact with the wall surface 1a, and the one end of the protection pipe 15 is fixed to the wall surface 1a. .

With this configuration, one end of the protection pipe 15 is completely fixed to the wall surface 1a of the muffler body 1, so that the protection pipe 15 is reliably supported, and the muffler body 1 is vibrated by, for example, vibration of the engine (not shown). The protective pipe 15 does not come off even when the vibration occurs. Further, when the protection pipe 15 is heated by contact with the exhaust gas, the heat is conducted from the protection pipe 15 to the wall surface 1a, and the heat conducted to the wall surface 1a is dissipated into the atmosphere. The temperature of the pipe 15 does not rise as much as the conventional muffler (Fig. 4). Therefore, the protective pipe 15 is less likely to be oxidized and is less likely to be deteriorated. The material of the protective pipe 15 is not particularly limited as long as it has heat resistance, but an aluminum-plated steel pipe (without holes) that is resistant to oxidation on the pipe surface and has high thermal conductivity is preferable.

FIG. 2 is a partially enlarged sectional view showing a second embodiment of the muffler. The muffler of this example is different from the above-mentioned embodiments in the following points. That is, as shown in FIG. 2, an outward flange 15a is formed on one end of the protection pipe 15 ', and the opening 8a of the protection plate 8 is passed through from the other end of the protection pipe 15', and then the muffler body 1 is removed. The flange 15a is almost entirely brought into contact with the inside of the wall surface 1a. Then, the peripheral edge of the flange 15a is welded to the wall surface 1a by continuous fillet welding 17 and fixed to the wall surface 1a. Since other configurations are common to the above-described embodiment, the same members are denoted by the same reference numerals as those in FIG. 1, and description thereof will be omitted.

According to the muffler of this example, the contact area between the end of the protection pipe 15 ′ and the wall surface 1a of the muffler body 1 is significantly increased, so that the heat of the protection pipe 15 ′ can be smoothed to the wall surface 1a. It can be released and the temperature of the protection pipe 15 'can be lowered.

FIG. 3 shows a third embodiment of the muffler, FIG. 3 (a) is an enlarged sectional view of a part thereof, and FIG. 3 (b) is a protection pipe used for the muffler of FIG. 3 (a). FIG. 3 is a perspective view showing an end portion of FIG. The muffler of this example is different from the above two examples in the following points. That is, at the end of the protective pipe 15 ″, three locking pieces 15b are extended outward at equal intervals in the circumferential direction as shown in FIG. 3 (b). The wall surface 1a of the muffler body 1 is provided with three slits 1b corresponding to the three locking pieces 15b of the protective pipe 15 ″, and the slit 1b is provided with the protective pipe 15 as shown in FIG. 3 (a). The locking pieces 15b of "" are loosely inserted and projected outward, and the end surface 15c (Fig. 3 (b)) of the protection pipe 15 "is brought into contact with the wall surface 1a. In this state, continuous fillet welding 18 is performed around the locking piece 15b so as to fill the gap between the slit 1b and the locking piece 15b, and one end of the protective pipe 15 is fixed to the wall surface 1a. Then, each locking piece 15b is bent toward the hexagonal head 10b of the tightening bolt 10 inward by about 90 °, and the tip of each locking piece 15b is brought into one engaging surface of the head 10b. Engage. Since the other structures are common to the above-mentioned two embodiments, the same members are designated by the same reference numerals as those in FIG. 1 and their explanations are omitted.

According to the muffler of this example, the circumferential position of the protective pipe 15 ″ is determined and the protective pipe 15 ″ is attached to the muffler body 1 with the locking piece 15 b loosely inserted in the slit 1 b of the wall surface 1 a. It can be temporarily stopped. Therefore, the work of attaching the protective pipe 15 ″ is simplified. Further, the locking piece 15b is loosely inserted into the slit 1b of the wall surface 1a and welded, and the protruding portion of the locking piece 15b is bent at a substantially right angle. Therefore, there is no possibility that the protective pipe 15 ″ will come off from the wall surface 1a of the muffler body 1 and come off. Moreover, since the heads 10b of the tightening bolts 10 are engaged with the tips of the three locking pieces 15b, the muffler body 1 may vibrate, or the tightening pipe 11 may be thermally deformed. Even then, the tightening bolt 10 does not rotate and loosen. In the case of this example, compared with the muffler of the second embodiment, the contact area between the protective pipe 15 ″ and the wall surface 1a of the muffler body 1 is small, but it is about the same as that of the muffler of the first embodiment. The 15 "temperature does not rise as much as a conventional muffler (Fig. 4).

Although the embodiment of the muffler is shown above, the muffler of the present invention can be implemented as follows.

A) When the temperature of the muffler body 1 on the side where the muffler body 1 is attached to the engine body can be kept low by a heat insulating material layer or the like, both ends of the protection pipe 15 may be brought into contact with the wall surface 1 a of the muffler body 1. .

B) One or four or more locking pieces 15b of the protection pipe 15 ″ may be provided.

[0027]

[Effect of device]

 As is clear from the above description, the muffler of the small engine of the present invention has the following effects.

(1) Since the heat of the protective pipe escapes to the wall surface of the muffler body and the heating due to contact with the exhaust gas is suppressed, the temperature rise of the protective pipe is considerably suppressed as compared with the conventional muffler, and the protective pipe is protected. The temperature will drop. Therefore, oxidation of the protective pipe is prevented, thermal deformation is unlikely to occur, and stable use can be achieved for a long time.

In the muffler according to claim 2, (2) since the end portion of the protection pipe is a flange and the contact area with the wall surface of the muffler body is large, the heat of the protection pipe is more likely to escape and the temperature rise of the protection pipe. Is further suppressed.

In the muffler according to claim 3, since the contact area between the end portion of the protection pipe and the wall surface of the muffler body is increased by (3) continuous fillet welding, the heat of the protection pipe easily escapes, Also, the support of the protective pipe becomes more reliable and firm compared to the conventional muffler.

In the muffler according to claim 4, (4) since the tip of the locking piece is engaged with the head of the tightening bolt, loosening of the tightening bolt is prevented when the muffler vibrates. It

In the muffler according to claim 5, (5) since the aluminum-plated steel pipe has a high thermal conductivity, the temperature rise of the protective pipe is further suppressed, and the aluminum-plated layer prevents oxidation during contact with exhaust gas. It

[Brief description of drawings]

FIG. 1 is an overall sectional view showing a first embodiment of a muffler for a small engine of the present invention.

FIG. 2 is a partially enlarged sectional view showing a second embodiment of the muffler of the present invention.

3 shows a third embodiment of the muffler of the present invention, FIG. 3 (a) is a partially enlarged sectional view, and FIG. 3 (b) is FIG.
It is a perspective view which shows the edge part of the protection pipe used for the muffler of (a).

FIG. 4 is an overall cross-sectional view showing a conventional example of a muffler for a small engine.

[Explanation of symbols]

 1 Muffler body 1a Wall surface 1b Slit 8 Protective plate 10 Tightening bolt 10b Head 11 Tightening pipe 12 Heat insulating material 15 ・ 15 '・ 15 "Protective pipe 15a Flange 15b Locking piece 16 ・ 17 ・ 18 Continuous fillet welding

Claims (5)

[Scope of utility model registration request] 1. A muffler tightening pipe is attached to the muffler main body by penetrating a muffler main body having a hollow expansion chamber, the circumference of the tightening pipe is covered with a heat insulating material, and In a muffler of a small engine having a structure in which a protection pipe for preventing scattering is attached to the periphery and is fixed to the main body side of the small engine by a tightening bolt inserted into the tightening pipe, at least one end of the protection pipe is connected to the muffler. A muffler for a small engine characterized by being brought into contact with the wall surface of the main body. 2. The muffler for a small engine according to claim 1, wherein an end portion of the protection pipe is formed into a flange, and the flange is brought into contact with a wall surface of the muffler body. 3. The muffler for a small engine according to claim 1, wherein continuous fillet welding is performed around a contact portion between the protection pipe and a wall surface of the muffler body. 4. At least one locking piece is extended to one end of the protection pipe, and a slit into which the locking piece can be inserted is formed on a wall surface of the muffler body, and the slit has the locking piece. Insert a through hole to form a fillet weld between the periphery of the slit and the locking piece, bend the locking piece toward the head of the tightening bolt, and tighten the tip of the locking piece. The muffler for a small engine according to any one of claims 1 to 3, wherein the muffler is engaged with a head of a bolt with a bolt. 5. The muffler for a small engine according to claim 1, wherein an aluminum-plated steel pipe having no hole is used for the protection pipe.