JPH1089065A - Multi cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diminish exhaust resistance in an exhaust introducing pipe, and properly arrange the attachment of a mounting flange, by forming a fanwise part in the exhaust introducing pipe inserted in the expansion chamber of an exhaust muffler, and seating the mounting flange arranged in the end inlet of this fanwise part, on a cylinder head circumferential surface. SOLUTION: Exhaust ports 2, 2 are arranged in the cylinder head of a water- cooled vertical type t2 air cylinder engine, an exhaust introducing pipe 5 is inserted in the expansion chamber 4 of an exhaust muffler 3, this exhaust introducing pipe 5 is fixed on an expansion chamber wall 6, and the exhaust ports 2, 2 are communicated with the expansion chamber 4 through the exhaust introducing pipe 5. Then, this exhaust introducing pipe 5 is arranged only one, a fanwise part 7 is formed to this exhaust introducing pipe 5 on the outer side of the expansion chamber 4, and mounting flanges 9 are arranged in the end inlets 8 of this fanwise part 7, then the mounting flanges 9 are seated and attached on a cylinder head circumferential surface 11 under a condition that respective exhaust port inlets 10, 10 and a cylinder head circumferential surface part 11a positioned between these exhaust port inlets 10, 10 are placed in the inside of the fanwise part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a multi-cylinder engine.

[0002]

2. Description of the Related Art FIG. 3 shows a prior art of a multi-cylinder engine. This is similar to the present invention, in which a plurality of exhaust ports 102 are provided in a cylinder head 101, an exhaust introduction pipe 105 is inserted into an expansion chamber 104 of an exhaust muffler 103, and the exhaust introduction pipe 105 is fixed to an expansion chamber wall 106. Then, the exhaust port 102
102 is configured to communicate with the expansion chamber 104.

In this prior art, the same number of exhaust introduction pipes 105 as the number of cylinders are provided, and the exhaust introduction pipes 105 are provided outside the expansion chamber 104 with the same diameter.
Out to 10 ・ 110, and each exhaust pipe 105.1
Mounting flanges 109 on the periphery of the entrance
109 are provided, and the respective mounting flanges 109, 109 are individually seated and mounted on the inlet peripheral portions of the respective exhaust ports 102, 102.

[0004]

The above prior art has the following problems. Since the exhaust introduction pipes 105 are led out toward the exhaust port inlets 110 with the same diameter outside the expansion chamber 104, the cross-sectional area of the passages of the exhaust introduction pipes 105 is narrow over the entire length. For this reason, the exhaust resistance in the exhaust introducing pipe 105 increases, the exhaust efficiency decreases, and it is difficult to obtain high output. The same number of exhaust introduction pipes 105 as the number of cylinders
Since it is inserted in the expansion chamber 04, the effective volume of the expansion chamber 104 is reduced, and it is difficult to obtain high noise reduction performance. Since the plurality of mounting flanges 109 are separated from each other, their relative postures are likely to be out of order. If the plurality of mounting flanges 109 are forcibly seated in an out-of-position state, stress is applied to these seating portions, and the sealing force of the seating portions is reduced.

The first invention has the following problems. Reduce exhaust resistance in the exhaust pipe. Increase the effective volume of the expansion chamber. Optimize the mounting of the mounting flange. The second invention has the following problems in addition to the problems of the first invention. To reduce the exhaust resistance in the exhaust muffler. The third invention has the following problems in addition to the problems of the first invention or the second invention. To reduce the exhaust resistance in the exhaust muffler.

[0006]

[Means for Solving the Problems]

(First Invention) In the first invention, as shown in FIG. 1, a plurality of exhaust ports 2 are provided in a cylinder head 1, an exhaust introduction pipe 5 is inserted into an expansion chamber 4 of an exhaust muffler 3, and this exhaust introduction is performed. A multi-cylinder engine in which the pipe 5 is fixed to the expansion chamber wall 6 and the exhaust ports 2.2 are connected to the expansion chamber 4 via the exhaust introduction pipe 5 is characterized as follows.

[0007] That is, as shown in FIG. 1, only one exhaust introduction pipe 5 is provided, and the exhaust introduction pipe 5 is provided outside the expansion chamber 4.
The exhaust port entrances 10 and 1 are provided with a mounting flange 9 at the front end entrance 8 of the extension part 7.
0 and the cylinder head peripheral surface portion 1 located between them
The mounting flange 9 is seated and mounted on the cylinder head peripheral surface 11 in a state where the first flange 1a faces the inside of the widening portion 7.

(Second invention) The second invention is the first invention, wherein the four-cycle two-cylinder engine has an explosion interval of 36 crank angles.
It is characterized by having equal intervals of 0 °.

(Third invention) According to a third invention, as shown in FIG. 2, in the first invention or the second invention, the cooling fan is located at a position deviated laterally from the cylinder center axis 12 when viewed from the front side of the engine. The cooling muffler 3 is characterized in that the turning center 13 of the cooling fan is arranged, and the exhaust muffler 3 faces the turning area 14 of the cooling fan from the rear side.

[0010]

Actions and effects of the present invention

(First Invention) The first invention has the following effects (see FIG. 1). The cross-sectional area of the exhaust introduction pipe 5 is increased at the widening portion 7. Therefore, the exhaust resistance in the exhaust pipe 5 is reduced, the exhaust efficiency is increased, and a high output is obtained. Since only one exhaust introduction pipe 5 is inserted into the expansion chamber 4,
The effective volume of the expansion chamber 4 is increased, and high noise reduction performance is obtained. Since the mounting flange 9 is provided at the front end entrance 8 of the divergent portion 7 having only one location, the posture of the mounting flange 9 is unlikely to be out of order. Therefore, the mounting of the mounting flange 9 can be properly performed, and the sealing force of the seating portion can be maintained high.

(Second Invention) The second invention has the following functions and effects in addition to the functions and effects of the first invention (see FIG. 1). Since the exhaust from the first cylinder and the exhaust from the second cylinder are less likely to overlap in the exhaust muffler 3, the exhaust resistance in the exhaust muffler 3 can be reduced, the exhaust efficiency can be increased, and a high output can be obtained.

(Third invention) The third invention has the following functions and effects in addition to the functions and effects of the first or second invention (see FIG. 2). Since the exhaust muffler 3 can be efficiently cooled by the cooling air, the volume of the exhaust is reduced, and the exhaust resistance in the exhaust muffler 3 is reduced. For this reason, the exhaust efficiency is increased and a high output is obtained.

[0013]

Embodiments of the present invention will be described with reference to the drawings. In the embodiment shown in FIGS. 1 and 2, a water-cooled vertical two-cylinder engine is used, and the configuration is as follows. As shown in FIG. 2, a carburetor 15, a fuel filter 16,
The fuel supply pump 17 is arranged, and the exhaust muffler 3 is arranged on the left side of the engine. A timing transmission case 18 is arranged at the front side of the engine.
And a working oil pump 20.

The structure of the exhaust system of this engine is as follows. As shown in FIG. 1, a plurality of exhaust ports 2 are provided in a cylinder head 1, an exhaust introduction pipe 5 is inserted into an expansion chamber 4 of an exhaust muffler 3, and the exhaust introduction pipe 5 is fixed to an expansion chamber wall 6. The exhaust ports 2 are connected to the expansion chamber 4 via the exhaust introduction pipe 5.

There are two exhaust ports 2.2. The expansion chamber 4 in the exhaust muffler 3 includes a first expansion chamber 26, a second expansion chamber 27,
It is partitioned into a third expansion chamber 28. The exhaust pipe 5 is
It is inserted into the expansion chamber 26. A plurality of exhaust outlets 29 are provided in the peripheral wall of the exhaust introduction pipe 5. The arrow 30 in FIG. 1 indicates the flow of exhaust gas.

In this embodiment, only one exhaust introduction pipe 5 is provided for the purpose of reducing exhaust resistance in the exhaust introduction pipe 5 and the like. 7, a mounting flange 9 is provided at the front end inlet 8 of the widening portion 7, and the exhaust port inlets 10, 10 and the cylinder head peripheral surface portion 11A located therebetween are brought into the widening portion 7. In this state, the mounting flange 9 is mounted so as to be seated on the cylinder head peripheral surface 11. The mounting flange 9 is provided around the front end entrance 8 of the tapered portion 7 in a series, and is fixed to the cylinder head peripheral surface 11 with a plurality of bolts 31. No exhaust manifold is required. Further, in order to reduce the exhaust resistance in the exhaust muffler 3, the four-cycle 2
The cylinders are used, and the explosion intervals are set at equal intervals of 360 ° in crank angle.

In this embodiment, in order to reduce the exhaust resistance in the exhaust muffler 3, as shown in FIG. 2, the cooling fan is located at a position deviated laterally from the cylinder center axis 12 when viewed from the front of the engine. A turning center 13 is arranged, and the exhaust muffler 3 faces the turning area 14 of the cooling fan from the rear side.

The structure of the intake device of this engine is as follows. That is, as shown in FIG. 1, two intake ports 21 are provided in the cylinder head 1, these are formed into a branch structure in which respective base ends are joined, and a common intake port inlet formed in the junction 22 is provided. 23 communicates with a mixture outlet 24 of the vaporizer 15. The vaporizer 15 is attached to the cylinder head 1 via a plate-like insulator 25. For this reason, the intake manifold becomes unnecessary, and the size of the carburetor 15 projecting to the side of the cylinder head 1 is reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining an engine according to an embodiment of the present invention. FIG. 1 (A) is a cross-sectional plan view of an exhaust device, and FIG. 1 (B) is a cross-sectional view taken along line BB of FIG. 1 (A). is there.

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

FIG. 3 is a diagram corresponding to FIG. 1A of an engine according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Exhaust port, 3 ... Exhaust muffler, 4 ... Expansion chamber, 5 ... Exhaust introduction pipe, 6 ... Expansion chamber wall, 7 ...
Point of divergence, 8: tip entrance, 9: mounting flange, 10 ...
Exhaust port inlet, 11 ... Cylinder head peripheral surface, 11a ...
Cylinder head peripheral surface portion, 12: center axis of cylinder head, 13: center of rotation of cooling fan, 14: region of rotation of cooling fan.

Continued on front page (72) Inventor Tamotsu Ohashi 64 Ishizukita-cho, Sakai City, Osaka Prefecture Inside Kubota Sakai Factory (72) Inventor Makoto Isomura 64 Ishizu-Kitamachi, Sakai City, Osaka Prefecture 64 Inside Kubota Sakai Factory (72) Inventor Tree Seiji Hon 64 Ishizu-Kitacho, Sakai-shi, Osaka Inside Kubota Sakai Works

Claims (3)

[Claims] A plurality of exhaust ports are provided in a cylinder head (1).
(2) and (2) are provided, and an exhaust pipe (5) is inserted into the expansion chamber (4) of the exhaust muffler (3), and the exhaust pipe (5) is connected to the expansion chamber wall.
(6) and the exhaust port (5)
(2) In a multi-cylinder engine configured by connecting (2) to the expansion chamber (4), only one exhaust introduction pipe (5) is provided, and the exhaust introduction pipe (5) is provided outside the expansion chamber (4). ) Is formed with a divergent portion (7), and a mounting flange (9) is provided at a front end entrance (8) of the divergent portion (7).
The exhaust port inlets (10), (10) and the cylinder head peripheral surface portion (11a) located between
(7) A multi-cylinder engine characterized in that the mounting flange (9) is mounted on the cylinder head peripheral surface (11) while facing the inside of the engine. 2. The multi-cylinder engine according to claim 1, wherein in a four-cycle two-cylinder engine, an explosion interval is 36 in crank angle.
A multi-cylinder engine characterized by having equal intervals of 0 °. 3. The multi-cylinder engine according to claim 1, wherein the rotation center (13) of the cooling fan is located at a position deviated laterally from the cylinder center axis (12) when viewed from the front side of the engine. Arrange and swivel area of this cooling fan
(14) A multi-cylinder engine characterized by having an exhaust muffler (3) facing from the rear side.