Muffler for V-type engine

A muffler for work vehicle V-type internal combustion engines is disclosed, which is mounted in a horizontal sideway position, with its axis placed perpendicularly with the longitudinal vehicle axis, kept a proper distance from the chassis or vehicle body so that it is disposed in full exposure to the atmosphere for proper cooling. A pair of spaced inlet ports are provided in the muffler, at locations adjacent to opposite ends thereof for receiving the exhaust gases from the engine through a pair of parallely extending, parallel exhaust pipes directly interconnected between the combustion chambers of the two cylinders and the muffler inlet ports, without using the conventional intermediate flexible corrugated connectors.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to a muffler for work vehicle V-type engines. 
(2) Description of the Prior Art 
To reduce the noisy sound of the exhaust gases as they escape at high speed 
the exhaust pipes of V-type engines in work vehicles such as a tractor, 
power lawn mower, riding-type sprinkler and combine, various types of 
mufflers have so far been proposed in the prior art. Referring to FIG. 3, 
a typical conventional muffler 3, which is represented by laid-open 
Japanese utility model application No. 53-50317, is supported in a 
lengthwise position in the bottom of the chassis 1 of the vehicle, with 
its axis laid parallel with the centerline of the vehicle. 
The exhaust pipe consists of an L-shaped inlet pipe 5 and an exhaust 
manifold 4. The inlet pipe 5 has its lower end connected to the inlet port 
of the muffler 3 and extends upward through the chassis 1 to put its upper 
end 5a for connection to the lower end 4a of the exhaust manifold 4. The 
inlet pipe 5 is connected to the exhaust manifold 4, not directly, but 
through a flexible corrugated connector 6, which is intended to prevent 
direct propagation of the vibrations from the muffler 3 to the engine 
while the vehicle is running on the road, since the muffler 3, mounted on 
the chassis 1, is subject to the vibrations owing to the conditions of the 
road surface. The exhaust pipe 4 consists of branched end portions 9 and 
10 for connection to the separate combustion chambers of the two cylinders 
in work vehicle V-type engines. 
However, those prior art mufflers have been found to have various 
difficulties. For example, in those work vehicles in which their V-type 
engine is mounted in a sidewise position, with the axis of the crankshaft 
laid perpendicularly with the longitudinal axis of the chassis, the 
arrangement is sometimes such that the one end portion 9 diverges from the 
extreme end of the exhaust pipe 4 while the other portion 10 branches off 
from it at a point some distance down from the junction where the portion 
9 is joined to the exhaust pipe 4. This configurational asymmetry of the 
end portions 9 and 10 with respect to the exhaust pipe 4 has been proved 
to constitute a cause of imbalance in the output and exhaust efficiency of 
the cylinders 7 and 8. 
Furthermore, in applications where the muffler 3 is mounted in a lengthwise 
position, as in FIG. 3, the muffler 3 stands with its side of the smaller 
surface area oriented in the direction of movement of the vehicle, which 
means a rather reduced cooling effect in the flow of air generated by the 
moving vehicle. This is not advantageous, since cooling helps a muffler to 
reduce the exhaust noise. 
In addition, the provision of the flexible corrugated connector 6 makes the 
entire exhaust pipe system undesirably great in size, and extend in the 
vicinity of the engine fuel system and air intake device, exposing them to 
a constant danger of heating by the higher surface temperature of the 
exhaust pipe system when exhaust gases are flowing therethrough. 
The present invention has been proposed to eliminate the above problems. 
SUMMARY OF THE INVENTION 
It is therefore a primary object of the present invention to provide an 
improved muffler for work vehicle V-type engines which is mounted for 
increased cooling and hence reduced exhaust noise. 
It is a further object of the present invention to provide such a muffler 
which permits the employment of cylinder-to-muffler exhaust pipes of equal 
length for increased cylinder performance and exhaust efficiency. 
It is an additional object to provide such a muffler which permits the use 
of an exhaust system of small size and simple structure. 
The above and other objects, features and advantages of the present 
invention will be more fully understood and appreciated from the following 
description of specific embodiments taken together with the accompanying 
drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring first to FIGS. 1a through 1c, features of the first preferred 
embodiment of the present invention will be described as it is mounted on 
a front engine tractor 11 having a chassis 14 and an engine compartment 
12. A V-type horizontal engine 13 is installed on the chassis in the 
compartment 12, with its two cylinders 15 and 16 arranged symmetrically 
with respect to the center line of the chassis. Under the engine 13 are 
provided mounted a pair of parallel arranged, spaced exhaust pipes 17 and 
18 which are in turn connected at a respective rear end thereof to the 
combustion chambers, not shown, of the cylinders 15 and 16 to receive 
exhaust gases therefrom. 
A muffler 21 according to the present invention is mounted in front of the 
engine compartment 12 in a horizontal position, with its axis held 
perpendicularly with that of the engine crankshaft. The muffler 21 is held 
in place by a rigid muffler support 22 which is in turn secured fixedly to 
a lower end portion of a vibration proof rubber bracket 19 through a bolt 
23. The bracket 19 is secured itself to a front part of the chassis 14 
through a bolt 20. 
Also, the muffler 21 has a pair of spaced inlet ports 24 and 25, located 
adjacent to opposite ends thereof, respectively, on the side facing the 
engine compartment. The exhaust pipes 17 and 18 extend forward and bend 
downward at a point adjacent to the front wall of the compartment 12 to 
brings their forward ends to connect to the ports 24 and 25, respectively. 
With this arrangement, the exhaust gases generated in the cylinders 15 and 
16 are conducted through the exhaust pipes 17 and 18 to the muffler 21 and 
discharged to the atmosphere, with proper noise reduction, through a 
tilted tail pipe 26 that is provided on the muffler on the opposite side 
to the ports 24 and 25. 
In the drawings, the numeral 29 designates a fuel pump which supplies fuel 
to the engine 13 through the carburetor 28, which is also connected to the 
air cleaner 27 for air intake. The engine 13 is also provided with a 
radiator 30, a fan 31 and a hot air discharge duct 32 for engine cooling. 
Since the operation of the engine 13 and its cooling system are known to 
those versed with the art, no description will be given here. 
Referring then to FIGS. 2a and 2b, a second preferred embodiment of the 
present invention will be described, as it is mounted on a riding type 
rear engine lawn mower, largely indicated at 35 in the drawing, having an 
engine compartment 36 and a chassis 14'. 
A vertical shaft V-type engine 13 is mounted in the compartment 36, with 
its cylinders 15 and 16 disposed symmetrically with respect to the center 
line of the vehicle body. Under the engine 13 are provided mounted a pair 
of parallel arranged, spaced exhaust pipes 17 and 18 which are connected 
at a respective rear end to the combustion chambers of the cylinders 15 
and 16 to receive exhaust gases therefrom when the engine is running. 
A muffler 21' according to the second embodiment of this invention is 
mounted on the chassis 14' adjacent to the rear wall of the compartment 
36, disposed in a horizontal position, with its axis extending 
perpendicularly with the longitudinal axis of the vehicle body. 
Also, the muffler 21' has a pair of spaced inlet ports 24 and 25, located 
adjacent to opposite ends thereof. The exhaust pipes 17 and 18 extend 
rearwardly to bring their rear ends to connect to the ports 24 and 25, 
respectively. 
With this arrangement, the exhaust gases generated by the cylinders in 
operation are conducted through the exhaust pipes 17 and 18 to the muffler 
21' and discharged to the atmosphere through a downwardly tilted tail pipe 
26' that are connected to the muffler 21' on the side opposite to the 
ports 24 and 25. The tail pipe 26' may preferably be opened to the 
atmosphere through an opening 37 bored in the lower rear wall of the 
comaprtment 36. 
The engine 13 has a carburetor 38 and, during operation, is supplied with 
fuel from the fuel supply and air through an air cleaner 37. A fan 39 and 
a pair of cooling air ducts 40 are provided adjacent to the cylinders 15 
and 16 to send cooling air through lower open ends of the ducts to cool 
the exhaust pipes 17 and 18 and the muffler 21'. 
In either of the above embodiments, since the muffler 21, 21' is bodily 
disposed in parallel with the axis of the engine crankshaft, the exhaust 
pipes 17 and 18 interconnected between the combustion chambers of the 
cylinders 15 and 16 and muffler inlet ports 24 and 25 are made 
substantially equal in length, permitting the equally distributed flow of 
exhaust gases between the exhaust pipes 17 and 18 during the engine 
operation. Consequently, output and exhaust efficiency can also be 
equalized between the cylinders 15 and 16. 
Furthermore, since the muffler 21 is mounted in a sidewise, with the side 
of the larger surface area oriented in the direction of movement of the 
vehicle, as may best be depicted in FIG. 1b, it can be conveniently cooled 
by the flow of air as the vehicle is moving in operation. Furthermore, if 
the muffler body is held detached enough way from the chassis 14 to expose 
its external surface to the atmosphere, proper cooling of the muffler 21 
can be achieved even when the vehicle is standing still. 
As for the second embodiment in FIGS. 2a and 2b, in the back of the engine 
compartment 36, the muffler 21' is placed in full exposure to the streams 
of cooling air discharged from the outlet ports 37 of the cooling air 
ducts 40 so that the muffler is properly cooled during the operation. 
Also, in either preferred embodiment, since the manner in which the muffler 
21, 21' can be installed with practical efficiency and performance on its 
vehicle enables its mounting location to be fixed near the engine 13, the 
exhaust pipes 17 and 18 laid to interconnect the muffler inlet ports 24 
and 25 and cylinder combustion chambers can be direct, without the 
intermediary of additional flexible corrugated connectors, and thus 
relatively short in length. In addition, this arrangement serves to have 
the exhaust pipes 17 and 18 supported at a proper distance away from the 
fuel and air intake systems so that the latter are less affected by the 
heat emitted from the surface of the exhaust pipes when the engine is 
running. 
The muffler may be mounted directly on the engine shell in rigid 
integration, welded in fixed position at two points in the muffler body. 
In construction, since the muffler according to the present invention can 
eliminates the additional intermediate flexible connector and exhaust 
pipe, conventional attaching operations can be saved. In addition, the 
exhaust pipes 17 and 18 may be formed from a one-piece pipe material, with 
simple pipe bending work. 
Although the above preferred embodiments have been described in view of 
application for those V-type engines with the axis of their crankshaft 
placed perpendicular with the longitudinal axis of the vehicle, they can 
be employed for V-type engines with their crankshaft axis held parallely 
with the longitudinal vehicle axis as well. In this case, the muffler may 
be supported in an erect or tilted position.