US 2922486 A
Description (OCR text may contain errors)
Jan. 26, 1960 W w. MCREE ET AL 2,922,466
: MUF'FLERS FOR DIESEL TRUCKS Filed MaICh 18, 1957 Afrox/vir United States Patent O Hce MUFFLERS FOR DIESEL TRUCKS William McRee, Dumont, and Del W. Jensen, Golden, Colo.
Application March 18, 19'57, Serial No. 646,907
1 Claim. (Cl. 181-57) This invention relates to a mufller more particularly designed for diesel engine tow trucks. It has been found exceedingly difficult to satisfactorily muflle the exhaust from large diesel engine tow trucks without creating power-absorbing back pressure on the engine. The principal object of this invention is to provide a simple and economical muffler construction for this particular use which will effectively reduce the exhaust noise without creating objectionable back pressure.
Another object of the invention is to so construct lthe improved muler that it will divide the volume of exhaust gases between two exhaust stacks so as to serve simultaneously as a muiller and an exhaust divider.
A further object of the invention is to provide a muffler of the above characteristics which can be quickly and easily installed in the present diesel install-ations with minimum effort.
Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy and efficiency. These wi-ll become more apparent from the following description.
In the following detailed description of the invention, reference is had to the accompanying drawing which forms a pant hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.
In the drawing:
Fig. 1 is a perspective view of the improved muffler illustrating its relation with an engine exhaust pipe and the exhaust stacks which are conventionally employed on diesel driven tow ltrucks;
Fig. 2 is an enlarged, longitudinal section through the improved mufller, taken on the line 2--2, Fig. 3; and
Fig. 3 is a cross-section, taken on the line 3 3, Fig. 2.
In Fig. 1, the tail pipe or exhaust pipe of a conventional diesel engine tow truck is indicated at with the exhaust stacks which usually arise at the sides of the tow truck cab indicated at 11.
The improved muiller comprises a rectangular box or housing 12 preferably of square cross-section and of greater length Ithan width. It has been found that if the length exceeds the width by approximately 1/3, the most satisfactory results are obtained. The size of the housing, of course, is proportional to the size of the engine. For truck engines of `approximately 250 horsepower, a most satisfactory size is 12 by 12 by 16". The housing 12 is closed at its front by a rectangular front plate 13 and at its rear by a similar rectangular rear plate 14. The plates 12 and 14 are permanently mounted in the extremities of the housing in any desired manner, such as by crimping or welding. As illustrated, the plates are Welded into the housing as indicated at 15.
A baille strip 16 is welded on the inner face of the rear plate 14. The baille strip 16 outlines a rectangular area, as indicated in broken line in Fig. 1, which corresponds y 2,922,486 Patented Jan. 26, 1960 in shape Ito the housing 12 but of smaller size than the housing so as to be spaced from each of the four inner walls of the latter.
An intake tubel 17, substantially corresponding in diameter to the exhaust pipe 10, is welded in and extends through the front plate 13 and is adapted to receive the exhaust pipe from the engine. The inner extremity of the intake tube 17 is bevelled forwardly and downwardly at substantially a 45 angle, as indicated at 18, so as to direct the discharge from the tube rearwardly and downwardly within the area enclosed by the rectangular baille 16. The tube 17 extends, at its greatest length, substantially one-half the length of thehousing 12 and this extended portion is provided with a plurality of pressure relieving perforations 19.
A cylindrical exhaust port 20, substantially corresponding to the area of the intake tube 17, is formed in each side wall of the housing 12 and a cylindrical exhaust sleeve 21 is formed about each of the ports 20 to receive the lower extremities of the exhaust stacks 11. The intake tube 17 enters the housing 12 above the horizontal center plane thereof and the ports 20 are positioned below the horizontal center plane.
It has been found that a muffler of the above described construction effectively reduces the noise of the exhaust and creates substantially no back pressure on the engine. The reasons for the high efficiency of the muffler are not all known. It is believed, however, the rectangular flat-sided shape of the housing principally contributes to the efllcient results. In use the hot exhaust gases entering the mufller receive a first expansion through the perforations 19 which creates an initial reduction in pressure. 'Ihe gases then continue to expand into the relatively large hollow open interior of the housing 12 until the pressure is reduced to slightly above atmospheric pressure. The gases discharging from the tube 17 strike directly against the flat rear plate 14 giving a rst reduction in velocity. The velocity is then reduced still further by impingement against the baille strip 16 and thence against the six flat walls of the housing all of which create a definite baflling effect. The substantially fully expanded gases can then flow in two directions through the unrestricted ports 20 and discharge from the stacks 11 very slightly in excess of atmospheric pressure.
It is believed that the six flat walls of the rectangular housing create ra plurality of internal counter currents and eddy currents in the gases which provide a cushioning effect to reduce the pressure and velocity with a minimum of noise. It is also believed that the unsupported flat wall areas flex and vibrate under variations in pressure to provide an additional absorbing or muilling effect. A still further muflling effect is obtained from the relative, vertical positions of the intake tube and exhaust ports so that a direct flow there between is positively prevented.
While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied within the scope of the appended claim, without departing from the spirit of the invention.
Having thus described the invention, what is claimed and desired secured by Letters Patent is:
A combination mufller and exhaust divider for muflling and dividing the exhaust of the engine of an automotive vehicle comprising: a rectangular horizontal housing of a substantially square cross section and having rectangular front and rear end plates and oppositely positioned rectangular side plates, the distance between said end plates being substantially equal to one and one-half times the distance between said side plates; a baille strip welded to the inner face of said rear end plate to outline a rectangular area thereon'spa'ced from the walls of said housing; anv'intake tube extending horizontally through said front end wall and extending within said housing for substantially onehalf the length of the latter, said intake tube being directed toward the upper portion of 5 said rectangular area; a circular exhaust porti through eachs'ide wall of said housing adjacent the front end wall thereof, said exhaust ports being positioned in a plane below said intake tube; and an exhaust stack extending irst outwardly and thence upwardly from'` each exhaust 10 port at right angles to `said intaketube.
UNITED STATES PATENTS Maxim Aug, 31, 1926 Paradise` .4 Oct. 9,1928- Zinsitz June 18, 1940 FOREIGN PATENTS v Germany j 1 Apr. 1, 1938