Flexible muffler mounting

A muffler mounting (26) for a muffler (21) which is connected to an internal combustion engine (11) by a rigid exhaust pipe (16). Previous mountings for such mufflers have either been of the rigid type, which subjects the muffler to undesired stresses resulting from shock, vibration or thermal expansion, or have utilized flexible rubber belting hangers which deteriorate rapidly when subjected to high temperatures. The present invention provides a relatively thin, flexible, generally-vertical metal hanger (52) comprised of a plurality of thin, stainless steel, strips (53) overlaid on one another, to flexibly connect and support the muffler (21) to the engine (11) or frame (12). The present invention is particularly useful in vehicles wherein the engine (11) is resiliently mounted on the frame (12) and wherein the muffler mounting (26) is subject to high temperatures, corrosion, and oxidation.

TECHNICAL FIELD 
This invention relates generally to internal combustion engines and exhaust 
systems and more particularly to a mounting for the muffler in such 
system. 
BACKGROUND ART 
In a typical vehicular environment, an internal combustion engine will be 
resiliently mounted on the frame of the vehicle and the exhaust system for 
the engine will include a rigid exhaust pipe extending from the exhaust 
manifold of the engine to a muffler with the hot exhaust gases then being 
discharged from the muffler through a tail pipe. 
Such a system poses significant problems in the provision of a reliable, 
simple and inexpensive support for the muffler. 
Because of the resilient engine mount, the engine will vibrate in many 
planes during operation, even when the vehicle is not moving. Such 
vibrations will be imparted to the muffler through the rigid exhaust pipe 
causing the muffler to similarly vibrate. Movement of the vehicle, 
particularly over rough terrain, will cause further shock and vibration of 
the muffler. The muffler support must, of course, have sufficient strength 
to support the weight of the muffler and prevent vibration and shock from 
causing failure of the exhaust pipe or muffler. 
The heat of the hot exhaust gases also presents a problem in that such heat 
will cause the exhaust pipe and muffler to expand and shift relative to 
the engine. The muffler support must also allow for relief of these 
stresses. 
The hot exhaust gases further present a problem in that the muffler becomes 
quite hot during operation and such heat will be transmitted by conduction 
to the muffler support. As a consequence, the muffler support must be able 
to withstand high temperatures without failure. This problem is increased 
in instances wherein the design of the vehicle makes it necessary to 
locate the muffler in a crowded space with a minimal amount of cooling air 
flow past the muffler. 
Corrosion from road contaminates and oxidation are further problems to be 
considered in providing a suitable muffler support which will not fail 
prematurely. 
Attempts have been made to mount the muffler rigidly to the engine so that 
there is no relative movement of the engine and muffler due to shock and 
vibration. In general, such attempts have not been satisfactory as the 
rigid mounts are subject to breaking and they restrain the muffler in such 
manner that substantial stresses are imposed on the muffler because of 
thermal expansion thereof. 
Flexible rubber belting straps members have also been used to suspend the 
mufflers. Such rubber belting straps do aid in protecting the muffler 
against shock, vibration and thermal expansion, but they are adversely 
affected by high temperatures and have a relatively short life before 
failure. 
In summary, there is a need for a simple, inexpensive and reliable muffler 
mount which will bear the weight of the muffler, which will withstand 
shock, vibration and thermal expansion forces, which is heat resistant, 
and which is resistant to corrosion and oxidation. 
DISCLOSURE OF INVENTION 
The present invention is directed to overcoming one or more of the problems 
as set forth above. 
In one aspect of the invention, this is accomplished in an engine and 
exhaust system wherein a muffler is connected at one location thereon to 
an engine by a rigid exhaust pipe extending therebetween by providing a 
rigid support bracket and a generally-vertical, flexible metal hanger 
fixed at the upper end thereof to the support bracket and fixed at the 
lower end thereof to another location on the muffler. 
In another aspect of the invention, the flexible hanger comprises a 
plurality of individual strip elements overlaid on one another. 
The foregoing and other aspects will become apparent from the following 
detailed description of the invention when considered in conjunction with 
the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to the drawings, FIG. 1 illustrates an engine and exhaust 
system 10 including an internal combustion engine 11 resiliently mounted 
on, or connected to, a vehicle frame 12 by a pair of laterally-spaced, 
front engine mounts 13 (only one of which mounts is shown) at the front of 
the engine and by a rear engine mount 14 at the rear of the engine. A 
rigid exhaust pipe 16 is rigidly connected at a first end 17 thereof to 
engine 11 and at the second end 18 thereof to a first end 19 of muffler 21 
(FIG. 4). Muffler 21 is typically of elongated, substantially cylindrical 
shape and is generally horizontally disposed and spaced away from the 
engine 11 and frame 12. As illustrated herein, muffler 21 has an arcuate 
heat shield 22 therearound and a tail pipe 23 extending therefrom. The 
second end 24 of muffler 21, i.e. the end 24 of the muffler opposite from 
the first end 19 thereof to which the exhaust pipe 16 is connected, is 
supported by the muffler mount 26 of the present invention. 
FIG. 1 also illustrates, in phantom, portions of the radiator 27 associated 
with the engine and portions of a frame-mounted counterweight system 28. 
In many vehicles, overall design considerations are such that the radiator 
27 and counterweight system 28, and other vehicle components (not shown) 
must be located relative to engine 11 such that there is a minimal amount 
of room in which the muffler 21 may be located and such that air flow past 
the muffler, needed to cool the muffler, is considerably restricted. 
Front engine mount 13 comprises a bracket 31 fixed to engine 11 and 
supported on frame member 32 of frame 12 by a resilient pad 33, the 
bracket 31 being secured to frame member 32 by bolt 34. 
Rear engine mount 14 comprises a rigid yoke 36 having a horizontal 
cross-member 37 and forwardly extending arms 38 and 39 which are bolted to 
the engine. The cross-member 37 is supported on frame member 41 of frame 
12 by a resilient pad 42 and is held in place relative to the frame member 
41 by bolt 43. 
The muffler mount 26 comprises a rigid muffler support bracket 46 having a 
lower flange 47 securely fixed, as by screws 48, to cross-member 37 of 
yoke 36, an upwardly extending portion 49 and a horizontally extending arm 
51. Because of the fixed connections of bracket 46 to yoke 36 and yoke 36 
to engine 11, bracket 46 and arm 49 thereof will move in unison with 
engine 11. That is, if engine 11 moves relative to the frame 12 because of 
engine vibration or vehicle shock, bracket 46 will also so move. 
A relatively thin, flexible, generally vertical, metal hanger 52, comprised 
of a plurality of thin sheet metal strip elements 53, overlaid on one 
another in face-to-face relation, extends downwardly from bracket arm 51 
to muffler 21 with the hanger 52 being generally perpendicular to the 
lengthwise axis of muffler 21. As best seen in FIGS. 3 and 4, the first, 
or upper, end 54 of hanger 52 is firmly fixed to bracket arm 51 by washer 
plate 56 and bolts 57, while the second, or lower, end 58 of hanger 52 is 
firmly fixed to end 24 of muffler 21 by spacer block 59, washer plate 61 
and bolts 62. 
Preferably, three metal strip elements 53 are used to make up hanger 52, 
each strip element being approximately 0.2 inches in thickness, so that 
the hanger 52 will have the desired strength and flexibility to provide 
proper support for muffler 21. Also preferably, strip elements 53 are made 
of stainless steel stock to provide high resistance to heat, corrosion, 
and oxidation. 
INDUSTRIAL APPLICABILITY 
Although its use is not so limited, the present invention is particularly 
useful in lift truck vehicles. 
As is apparent from the foregoing description, any movement of engine 11 
relative to frame 12 will be transmitted by the rigid exhaust pipe 16 to 
end 19 of muffler 21. Such movement of engine 11 will likewise be 
transmitted through yoke 21, and bracket 46 and hanger 52 to end 24 of 
muffler 21. This support of the muffler, from both ends thereof, by the 
rigid exhaust pipe 16 and the rigid bracket 46, which both move in unison 
with each other, enables the muffler to resist shock and vibration without 
undue stresses being imposed thereon and without undue stresses being 
imposed on the muffler mount 26. 
Because of the height and relatively large width of hanger 52, the end 24 
of muffler 21 will be held securely against vertical, forward, or rearward 
movement relative to engine 11. At the same time, the thinness of hanger 
52 will permit the hanger to flex easily to prevent stresses from being 
imposed on the muffler on the muffler support because of thermal 
expansion. For example, axial expansion of muffler 21 will cause hanger 52 
to flex laterally. Axial expansion of exhaust pipe 16 will force end 19 of 
muffler 21 rearwardly away from engine 11, but such force will be relieved 
by the twisting of hanger 52 about its vertical axis. 
The use of a plurality of thin strip elements 53 provides better 
flexibility than if a single thick element were used, since each strip 
element 53 can flex independently and follow the contour of the others. 
Also, since each thin strip element 53 has a small section modulus, the 
stress level in each strip element is relatively low for a given amount of 
hanger deflection. As a result, this makes the arrangement highly 
resistant to fatigue type of loading. 
The present invention thus provides a muffler support which is simple and 
inexpensive, which protects the muffler from stresses resulting from 
shock, vibration and thermal expansion, and which is highly resistant to 
heat, corrosion, and oxidation. 
Other aspects, objects and advantages of this invention can be obtained 
from a study of the drawings, the disclosure and the appended claims.