JPH08165923A - Muffler of engine - Google Patents

Abstract

PURPOSE: To heighten the degree of freedom of the size and spot welding position of armour members such as a stay, a thermal insulation plate and so on spot-welded to the outer surface of an outside plate, and to improve the strength and durability of the armour members in a muffler formed by joining a pair of outside plates to each other by all-round caulking. CONSTITUTION: A pair of outside plates 15, 16 are joined to each other by all-round caulking to form a muffler 9, and armour members 11, 12 are spot- welded to the outer surfaces of the outside plates 15 which has formed the muffler 9. A discharge opening 19 for discharging the exhaust gas which flows into the muffler 19 to the atmosphere is formed on the outside plate 16, the discharge opening 19 is formed to be positioned and sized so that one electrode for spot welding can be inserted toward the inner surface of a part of the outside plate 15 where to spot-weld the armour members 11, 12, and one electrode for spot-welding is inserted through the discharge opening 19 to spot-weld the armour members 11, 12 on the outside plate 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine muffler formed by joining a pair of outer plates by caulking all around.

[0002]

2. Description of the Related Art Conventionally, in a small engine having a total displacement of 50 cc or less, as shown in FIG.
A muffler 3, which is formed by joining 2 around each other by caulking, is widely used. In addition, one side plate 1 has an inlet 4 through which exhaust gas generated in the cylinder flows into the muffler 3.
Is formed, and the other outer plate 2 is formed with a discharge port (not shown) for discharging the inflowing exhaust gas into the atmosphere.

In such a muffler 3, a stay 5 is spot-welded to the outer surface of the muffler 3, and the stay 5 is used to attach the muffler 3 to the engine body. Here, the spot 5 is spot-welded to one of the outer plates 1 before the entire circumference is crimped, and after the stay 5 is spot-welded to the outer plate 1, the outer plate 1 and the other outer plate 2 are joined together. Are joined by caulking all around to form a muffler 3.

The outer plate 1 in which the stay 5 is spot-welded
In order to smoothly carry out the entire circumference of the caulking with the other outer plate 2, it is necessary to arrange the stay 5 so as not to project from the peripheral edge of the caulking so as not to interfere with the entire circumference of the caulking. . Further, it is necessary to form a flat surface on the outer surface of the outer plate 1 for spot welding the stay 5. Therefore, the recess 5a having a flat surface is formed on the outer plate 1, and the stay 5 bent in the recess 1a in a substantially L shape.
Are spot welded.

Next, in an engine in which the muffler and the fuel tank are arranged close to each other, a heat shield means for preventing heat from the muffler from reaching the fuel tank is required. As disclosed in JP-A-3-127024, there is one in which a heat shield plate is detachably mounted between a muffler and a fuel tank.

[0006]

Since the recess 1a is formed in the outer plate 1 and the stay 5 is spot-welded, the muffler volume becomes small, and the muffler volume for ensuring sufficient noise reduction performance is ensured. Must increase the outer diameter of the muffler 3, and cannot reduce the size of the muffler 3 and the engine as a whole.

Further, the restrictions on the size and mounting position of the stay 5 become large, and it is difficult to sufficiently enhance the strength and durability of the stay 5.

On the other hand, as disclosed in Japanese Utility Model Laid-Open No. 3-127024, when a heat shield plate is detachably mounted between the muffler and the fuel tank, the heat shield plate increases as the engine speed increases. Vibration increases and engine speed is 1
In an engine used at more than 2000 rpm, the durability of the heat shield plate is significantly reduced.

[0009]

According to the present invention, a pair of outer plates are joined by caulking all around, and an inflow port into which exhaust gas generated in a cylinder flows and an exhaust gas that flows in are discharged toward the atmosphere. In a muffler in which a discharge port is formed in the outer plate, the discharge port is formed at a position and a size where one electrode for spot welding can be inserted toward the inner surface of a portion of the outer plate where the exterior member is spot welded. did.

[0010]

When the exterior member is spot-welded to the outer surface of the outer plate, a pair of outer plates are joined by caulking all around to form a muffler, and then one electrode for spot welding is introduced into the muffler from the discharge port. It is performed by inserting and energizing between this electrode and the other electrode positioned outside the muffler.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. An exhaust flange 7 is formed on the cylinder block 6 of the two-cycle engine, and a muffler 9 is fastened and fixed to the exhaust flange 7 with a bolt 10 via a gasket 8. A stay 11 as an exterior member and a heat shield plate 12 are spot-welded to the muffler 9, and the crankcase 13 of the two-cycle engine is used.
The stay 11 is screwed to the tip of a boss 14 projecting from.

The muffler 9 is formed by joining a pair of outer plates 15 and 16 by caulking all around, and the stay 11 and the heat shield plate 12 are spot-welded to one outer plate 15. An inflow port 17 is formed in the outer plate 15, and this inflow port 17 communicates with an exhaust passage 18 formed in the exhaust flange 7 in a state where the muffler 9 is attached to the exhaust flange 7. ing. Further, the other outer plate 16 is formed with a discharge port 19 for discharging the exhaust gas flowing into the muffler 9 toward the atmosphere. An exhaust port body (not shown) that determines the exhaust gas emission direction is screwed to the emission port 19.

Next, spot welding of the stay 11 and the heat shield plate 12 to the outer plate 15 is performed after the outer plates 15 and 16 are joined by caulking all around to form the muffler 9. In addition, the discharge port 19 has a position and a size such that one electrode (not shown) for spot welding can be inserted toward the inner surface of the spot where the stay 11 and the heat shield plate 12 are spot-welded in the outer plate 15. Is formed.

In such a structure, the spot welding of the stay 11 and the heat shield plate 12 to the outer plate 15 is performed by the outer plate 1.
A portion for performing spot welding on the outer plate 15 while inserting one electrode for spot welding into the muffler 9 from the discharge port 19 after forming the muffler 9 by joining 5, 16 to each other by caulking all around. The other electrode is brought into contact with the outer surface of the stay 11 or the heat shield plate 12 that is brought into contact with the inner surface of the outer plate 15 and the outer surface of the outer plate 15, and electricity is applied between these electrodes. In this way, since spot welding is performed after the outer plates 15 and 16 have been swaged all around, there is no member protruding from the caulking periphery during the work of this full swaging, so that the joining work by swiveling around the entire circumference can be performed smoothly. It
Moreover, the recessed portion 1 as described in the conventional example of FIG.
Since it is not necessary to form a on the outer plate 15, the outer diameter dimension of the muffler 9 can be reduced and a sufficient muffler volume can be secured. Therefore, it is possible to obtain the muffler 9 that is small in size and has excellent sound deadening performance.

Since the stay 11 and the heat shield plate 12 are spot-welded to the outer plate 15 after the muffler 9 is formed, the stay 11 and the heat shield plate 12 can be freely attached with respect to their sizes and mounting positions. Grows larger. Therefore, the strength of the stay 11 and the heat shield plate 12 can be sufficiently increased, and the durability can be improved. In particular, with respect to the heat shield plate 12, as compared with the detachable type disclosed in Japanese Utility Model Laid-Open No. 3-127024, vibration and noise accompanying the rotation of the engine are not generated, and the durability is significantly improved.

The work of attaching the muffler 9 to which the stay 11 and the heat shield plate 12 are spot-welded to the exhaust flange 7 is performed by aligning the inlet 17 and the exhaust passage 18 with each other, and then the bolt 10 and the bolt 10 are attached. The tightening tool is inserted into the muffler 9 through the discharge port 19.

[0017]

As described above, according to the present invention, a pair of outer plates are joined by caulking all around, and the inflow port into which the exhaust gas generated in the cylinder flows and the inflowing exhaust gas are discharged to the atmosphere. In a muffler in which a discharge port is formed in the outer plate, the discharge port is formed at a position and a size where one electrode for spot welding can be inserted toward the inner surface of a portion of the outer plate where the exterior member is spot welded. Therefore, spot welding of the exterior member to the outer surface of the outer plate can be performed after the pair of outer plates are joined by caulking all around to form the muffler, so that the degree of freedom regarding the shape of the outer member and the spot welding position is increased. The outer diameter of the muffler can be reduced because the strength and durability of the outer member can be sufficiently increased, and it is not necessary to form a recess for spot welding the outer member on the outer plate. Also it is possible to secure a sufficient muffler capacity, therefore, it has an effect such as can be obtained excellent muffler silencing performance while being compact.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a perspective view showing a muffler of a conventional example.

[Explanation of symbols]

 9 Muffler 11,12 Exterior member 15,16 Skin 17 Inflow port 19 Discharge port

Claims (1)

[Claims] 1. A pair of outer plates are joined by caulking all around,
In a muffler in which the outer plate has an inflow port into which the exhaust gas generated in the cylinder flows in and a discharge port that discharges the inflowing exhaust gas toward the atmosphere, in a place where the exterior member of the outer plate is spot-welded. A muffler for an engine, characterized in that the emission port is formed at a position and a size where one electrode for spot welding can be inserted toward the inner surface.