JPH11324643A - Exhaust muffler cooling device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust muffler cooling device for an engine which has a muffler cover constituted of a single part, is inexpensive, satisfactrily cools the exhaust muffler, and prevent the heating of the muffler cover outside surface by radiating heat of the exhaust muffler. SOLUTION: A muffler cover 31 is constituted of a single front wall 31a covering the front face of an exhaust muffler 3, and an internal circumferential wall 31b and an outer circumferential wall 31c integrally continued in the circumferential edge of the front wall 31a and arranged double, inside and outside, so as to cover the circumferential face of the exhaust muffler 3, a cooling air introducing passage 33 is formed between the inside faces of the front wall 31a and the internal circumferential wall 31b and the outside face of the exhaust muffler 3, and a lot of heat radiating fins 35 are projected to the outside face of the front wall 31a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust muffler attached to an engine, which covers a front surface and a peripheral surface of the exhaust muffler and defines a muffler cover between the muffler cover and the muffler cover. The present invention relates to an exhaust muffler cooling device for an engine, which cools an exhaust muffler by flowing air.

[0002]

2. Description of the Related Art Conventionally, in an exhaust muffler cooling device of this type, an inner cover made of a steel plate that covers the front and peripheral surfaces of the exhaust muffler with a cooling air passage interposed therebetween, and a synthetic resin that covers the inner cover. The exhaust muffler is cooled by the air flowing through the cooling air guide passage, and the outer cover is not heated by the radiant heat of the exhaust muffler.

[0003]

SUMMARY OF THE INVENTION In the above conventional device,
Since the muffler cover is composed of two parts, the inner cover and the outer cover, the number of parts is large and cost reduction is difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and comprises a muffler cover composed of a single part, which is inexpensive, has good cooling of the exhaust muffler, and uses radiant heat of the exhaust muffler. Can prevent heating of the muffler cover outer surface,
An object of the present invention is to provide an exhaust muffler cooling device for the engine.

[0005]

In order to achieve the above object, the present invention provides a muffler which covers a front surface and a peripheral surface of an exhaust muffler attached to an engine and defines a cooling air guide passage therebetween. In an exhaust muffler cooling device for an engine provided with a cover, a single front wall covering the front surface of the exhaust muffler, and an inner and outer double wall are arranged integrally with the peripheral edge of the front wall to cover the peripheral surface of the exhaust muffler. The muffler cover is constituted by the inner peripheral wall and the outer peripheral wall, and a cooling air duct is formed between the inner surface of the front wall and the inner peripheral wall and the outer surface of the exhaust muffler. The first feature is that fins are protruded.

According to the first feature, the exhaust muffler can be directly cooled by the cooling air flowing through the cooling air duct. Further, since the radiant heat of the exhaust muffler is blocked by the inner peripheral wall and hardly acts on the outer peripheral wall, heating of the outer peripheral wall can be effectively prevented. In addition, the cooling air flowing through the cooling air duct cools the front wall of the muffler cover, and the radiation fins on the outer peripheral wall radiate heat to the atmosphere.
The temperature at the tip of the radiation fin can be kept relatively low. Therefore, contact of an operator or the like with the outer surface of the outer peripheral wall and the tip of the radiation fin is allowed. In addition, the muffler cover can be formed as a single component, which can contribute to cost reduction.

[0007] In addition to the above-mentioned features, the present invention provides, in addition to the above-mentioned features, when the distance between the radiating fins is A and the height of each radiating fin is B, A is set to a size that a general human finger cannot enter. A second feature is that the radiation fins are formed and arranged so that A / B <2.0.

According to the second feature, it is possible to reliably prevent the finger of the worker or the like who has touched the radiation fin from coming into contact with the outer surface of the front wall which is higher in temperature than the radiation fin.

Further, the present invention has a third feature that, in addition to the first or second feature, the muffler cover is integrally formed of a synthetic resin.

[0010] According to the third feature, the weight of the muffler cover can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIG. 1 is a perspective view showing an example of use of an air-cooled engine provided with an exhaust muffler cooling device of the present invention, FIG. 2 is a longitudinal front view of the engine, FIG. 3 is a sectional view taken along line 3-3 of FIG. FIG. 4 is a front view of the muffler cover, and FIG. 5 is a rear view of the muffler cover.

First, as shown in FIG.
Is configured as a hand-held type and is attached to, for example, a drive unit of a power trimmer T. Since the power trimmer T is used to turn the cutter in all directions depending on the working state,
Each time, the engine E is also greatly inclined or inverted, and the driving posture is not constant.

Referring to FIGS. 1 and 2, a carburetor 2 and an exhaust muffler 3 are respectively attached to an engine body 1 of the air-cooled engine E before and after the engine body 1, and an air cleaner 4 is attached to an inlet of the carburetor 2 at an intake path. . A fuel tank 5 is mounted on the lower surface of the engine body 1. The carburetor 2 is provided with a diaphragm pump that pumps up fuel from the fuel tank 5 using the pulsation of the intake air of the engine E and returns the excess fuel to the tank 5. Can be supplied.

The engine body 1 comprises a cylinder block 6 integrated with a head and a crankcase 7 joined to a lower end surface of the cylinder block 6. The cylinder block 6 is a single cylinder housing a piston 8. A cylinder 9 is provided at the center, and a number of cooling fins 10 are provided around the cylinder 9.
It has.

The crankcase 7 comprises a pair of upper and lower case halves 7a, 7b bolted to each other, and is connected to a piston 8 via a connecting rod 11.
2 is supported between the two case halves 7a, 7b.

An oil reservoir 14 adjacent to the crank chamber 13 is formed at one end of the crankcase 7, and an oil slinger 15 for stirring the lubricating oil stored in the chamber 14 to generate an oil mist is provided on the crankshaft. 12 is fixed. The oil mist generated in the oil reservoir 14 is supplied to each part of the engine E for lubrication.

At one end of the crankshaft 12, a rotor 21 with a cooling fan 20 of a flywheel magneto 19 is fixed, and a centrifugal clutch 24 is interposed between the rotor 21 and a drive shaft 23 for a working machine.

The engine body 1 is provided with a baffle plate 24 for covering the periphery of the rotor 21 and the cylinder block 6 and a lower cover 25 for covering the lower surface of the fuel tank 5. A cooling air passage 26 is formed around the exhaust muffler 3 through the periphery.
The inlet 26i is provided on the peripheral wall of the lower cover 25.

The exhaust muffler 3 is fixed by a plurality of bolts 17 (see FIG. 5) so that the inside thereof communicates with the exhaust port 16, and an exhaust outlet pipe 27 is opened in the peripheral wall. A heat shield plate 30 is sandwiched between the exhaust muffler 3 and the cylinder block 6. A muffler cover 31 that covers the front surface and the peripheral surface of the exhaust muffler 3 is fixed to a plurality of lugs 30 a formed on the peripheral edge of the heat shield plate 30 with bolts 31.

As shown in FIGS. 3 to 5, the muffler cover 31 is integrally formed of synthetic resin.
A single front wall 31a that covers the front of the exhaust muffler 3, and an inner and outer double peripheral wall that covers the peripheral surface of the exhaust muffler 3 integrally with the peripheral edge of the front wall 31a, that is, the inner peripheral wall 31b and the outer peripheral wall 3a.
1c. The inner peripheral wall 31b is arranged so that its open end is in contact with the heat shield plate 30, and a first cooling air guide passage 33 is provided between the inner surfaces of the inner peripheral wall 31b and the front wall 31a and the outer surface of the exhaust muffler 3. The inlet 33i is formed in a notch on one side of the outer peripheral wall 31c, and the outlet 33o is formed on the inner and outer peripheral walls 31b, 31c.
The exhaust outlet pipe 27 is provided at a portion facing the exhaust outlet pipe 27.

A second cooling air guide path 34 is defined between the inner and outer peripheral walls 31b and 31c, and an inlet 34i of the second cooling air guide path 34 is provided below the outer peripheral wall 31c so as to communicate with the cooling air passage 26. The outlet 34o is provided on the outer peripheral wall 31.
A large number of slits are provided above c. Therefore,
The inlet 33i of the first cooling air duct 33 is connected to the second cooling air duct 3
4 and the cooling air passage 26 through the inlet 34i.

A large number of radiation fins 35 are formed on the outer surface of the front wall 31a. At this time, when the distance between the heat radiation fins 35 is A and the height of each heat radiation fin 35 is B, A is set to a size that makes it difficult for ordinary fingers to enter, and A / B <2.
The radiation fins 35 are formed and arranged so as to be zero. Specifically, for example, A = 10.5 mm, B = 7 mm
Is set.

Next, the operation of this embodiment will be described.

When the cooling fan 20 is driven to rotate by the crankshaft 12 during operation of the engine E, the outside air sucked into the inlet 26i, that is, the cooling air, cools the fuel tank 5, the crankcase 7 and the cylinder block 6 sequentially. While passing through the cooling air passage 26. Next, the cooling air is supplied to the first and second cooling air ducts 33 of the muffler cover 31,
34, the cooling air flowing through the first cooling air guide path 33 directly cools the exhaust muffler 3 and also cools the inner peripheral wall 31b and the front wall 31a of the muffler cover 31, and then the exhaust outlet pipe of the exhaust muffler 3. Exit 3 with exhaust gas discharged from 27
It escapes from 3o into the atmosphere. Further, the cooling air flowing through the second cooling air guide path 34 cools the inner peripheral wall 31b of the muffler cover 31, and then flows out from the outlet 34o to the atmosphere.

As described above, the inner peripheral wall 31b of the muffler cover 31 is cooled by the cooling air from inside and outside thereof.
In addition, the radiant heat of the exhaust muffler 3 is blocked by the inner peripheral wall 31b and does not act on the outer peripheral wall 31c.
1c can be effectively prevented.

On the other hand, since the front wall 31a of the muffler cover 31 is single, the radiant heat of the exhaust muffler 3 is directly received, but the inner surface is cooled by the cooling air flowing through the first cooling air guide passage 33 as described above. The heat radiation fins 35 on the outer surface of the front wall 31a dissipate heat to the atmosphere, so that the temperature of the radiation fins 35, particularly at the distal end, can be kept relatively low. Therefore, contact of an operator or the like with the outer surface of the outer peripheral wall 31c and the tip of the radiation fin 35 is allowed.

Moreover, since the distance A between the heat radiation fins 35 is such that the fingers of ordinary people are difficult to enter, the finger touching the heat radiation fins 35 is more than the heat radiation fins 35. The contact with the outer surface of the high-temperature front wall 31a can be prevented. At that time, the radiation fins 3
5 When the distance between each other is A and the height of each radiating fin 35 is B, if the radiating fins 35 are formed and arranged so that A / B <2.0, contact with the outer surface of the front wall 31a can be prevented. It can be prevented more reliably.

In addition, since the muffler cover 31 is a single component integrally formed of a synthetic resin, the cost and the weight can be reduced.

The present invention is not limited to the above embodiments, and various design changes can be made without departing from the gist of the present invention.

[0031]

As described above, according to the first aspect of the present invention, a single front wall for covering the front of the exhaust muffler and a peripheral surface of the exhaust muffler which is integrally connected to the peripheral edge of the front wall are provided. The muffler cover is constituted by an inner peripheral wall and an outer peripheral wall which are arranged in two layers, and a cooling air duct is formed between an inner surface of the front wall and the inner peripheral wall and an outer surface of the exhaust muffler. Since a large number of radiating fins are protruded on the outer surface of the muffler, the muffler cover can be made into a single component, thereby reducing the cost while cooling the exhaust muffler and heating the outer peripheral wall of the cover and the radiating fins. Can be effectively suppressed,
Human contact with them can be tolerated.

According to a second feature of the present invention, when the distance between the radiating fins is A and the height of each radiating fin is B, A is set to a size that is difficult for ordinary fingers to enter. , A / B <2.0, the heat radiation fins are formed and arranged, so that the finger of the person touching the heat radiation fins is prevented from coming into contact with the outer surface of the front wall which is higher in temperature than the fins. be able to.

Further, according to the third feature of the present invention, since the muffler cover is integrally formed of synthetic resin, the weight of the cover can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of use of an air-cooled engine provided with an exhaust muffler cooling device according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view of the engine.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a front view of a muffler cover.

FIG. 5 is a rear view of the muffler cover.

[Explanation of symbols]

 3 Exhaust muffler 31 Muffler cover 31a Front wall 31b Inner peripheral wall 31c Outer peripheral wall 33 ... Cooling air duct (first cooling air duct) 35 ··· Heat radiation fins A ································· Engine

Claims (3)

[Claims] An exhaust muffler (3) attached to an engine (E) is provided with a muffler cover (31) for covering a front surface and a peripheral surface thereof and defining a cooling air duct (33) therebetween. An exhaust muffler cooling device for an engine, a single front wall (31a) covering the front of the exhaust muffler (3);
The muffler cover (31) comprises an inner peripheral wall (31b) and an outer peripheral wall (31c) which are integrally and continuously arranged on the peripheral edge of the front wall (31a) to cover the peripheral surface of the exhaust muffler (3). A cooling air duct (33) is formed between the inner surface of the front wall (31a) and the inner peripheral wall (31b) and the outer surface of the exhaust muffler (3), and the outer surface of the front wall (31a) is formed. An exhaust muffler cooling device for an engine, wherein a number of radiating fins (35) are protruded from the exhaust muffler. 2. The radiating fins (35) according to claim 1, wherein the distance between the radiating fins (35) is A,
When the height of B is set to B, the heat radiation fins (35) are formed and arranged so that A is set to a size that makes it difficult for ordinary fingers to enter, and A / B <2.0. Characterized by an engine exhaust muffler cooling system. 3. An exhaust muffler cooling device for an engine according to claim 1, wherein said muffler cover (31) is integrally formed of synthetic resin.