US2125449A

US2125449A - Muffler

Info

Publication number: US2125449A
Application number: US14850A
Authority: US
Inventors: Riethmiller Ruth
Original assignee: HAYES IND Inc
Current assignee: HAYES IND Inc
Priority date: 1935-04-05
Filing date: 1935-04-05
Publication date: 1938-08-02
Anticipated expiration: 1955-08-02

Description

MUFFLER G. A.. KINGSLEY Filed April 5, 1935 Patented Aug. 2, 1938 UNlTED STATES PATENT GFFHCE MUFFLER Application April 5, 1935, Serial No. 14,850

S Claims.

The present invention relates to improvement in muliler structure for internal combustion engines and having particular reference to mufers of the general type illustrated by U. S. Patent No. 1,931,736 to Noblitt et al.

In mufrlers of the above -mentioned type to obtain compactness of structure the gases are passed back and forth through the muiiler casing between the inlet and discharge openings.

lo The design of the muier is such that the gases have a relatively free passage through the muffler casing avoiding the creation of objectionable back pressure yet at the same time the muffler is characterized by its silencing efficiency.

l5 It is an object of the invention to simplify and thus reduce the cost of manufacture of the above type of muflier and at the same time enn hance the silencing efficiency thereof.

Another object is to provide a mufier which 30 is strong and durable and particularly designed.

to resist destruction by backfire.

A still further object is to produce a muffler n which deceleration noises are avoided as well as high pitch noises or whistling at time of :l5 high gas velocity.

in the specific embodiment shown in the above mentioned patent three separate tubes are provided in the muffler casing for a. triple passage of 'the gases. According to the present inven- :30 tion a triple passage of the gases through the casing is possible With a pair of tubes; the mufiier casing acting as a conduit for the gases from one end of the muilier casing to the other and for interconnecting such tubes. in the pre- ;35 ferred form, these main tubes, through which the main ficw of gases pass, are each concentrically supported within intermediate tubes which define a chamber about each tube separating the same from the muliler casing. These chambers Ll0 are divided up by partitions into separate chambers arranged longitudinally of each tube. The main tubes are perforated to effect communication with the chamber surrounding the same. In

F the silencing of the exhaust gases of certain engines perforations may also be advantageously provided in the intermediate tubes to effect a diffusion or short circuiting of the gases into the conduit defined by the muflier casing.

In the accompanying drawing wherein two forms of the invention are illustrated,

Fig. l is a cross-sectional view through the muffler casing,

Fig. 2 is a cross-sectional view taken on line 55 II--I of Fig. l, and

Fig. 3 is a view similar to Fig. 2 of a modified form of the invention.

In the mufller illustrated in Figs. l. and 2, the cylindrical outer casing l is closed at opposite ends by headers l2 and Mi having inlet and discharge openings it and i8, respectively. Tubes 2o and 22 constituting main conduits for the flow of gases between the inlet and outlet openings are concentrically supported within intermediate tubes Eri and 2t by baffle members 2B. These pairs of concentrically associated tubes are located in overlapping relation within the casing iii to provide chambers 3@ and 32 communicating with longitudinally extending chambers 34 and 36 dened within the casing lil. The tube is shown communicating with the inlet it through a conical connector Si.

The tubes 2li and 22 are shown as perforated to effect communication with the chambers it@ which act as acoustic wave filters or resonator in a manner well known. Preferably the perforations in the tubes 2t and 'Z2 take the form of angularly disposed elongatedslots l2 as such a configuration has been found to eliminate the creation of high pitch noises or whistling in the muffler due to the passage of the gases across the same, all as fully discussed and treated in my copending application Serial No. 14,848, 1filed April 5, i935. These chambers fi@ may be closed in some instances and in others it has been found advantageous to perforate the same in some suitable manner such as with slots it which permits a diffusion or short circuit of a portion of the gas ow out of the intermediate tubes 2li and 2t into the chambers 35i and 3K5 or from the intermediate tube 24 through the chambers 3Q and 3'3 into the intermediate tube it and hence into the tube 22 into the discharge dow. The size and number of perforations in the chambers fil may be varied at will to regulate the back pressure in the muliler. Also this diffusion of the gas iow between the intermediate tubes is of assistance in noise suppression as the sound waves from the inlet and discharge tubes 2G and 22 meet and cancel cach other.

It is to be noted that the connection @el is shown as provided with perforations it similar to those in the tubes 2Q and E2 permitting a portion of the gases to flow into the chamber l-S and hence into the chambers and through perforations i9. By regulating the 'perforate area in the connection 38 the same muler structure is adaptable to different engines with controlled back pressure. Obviously by short circuiting a portion of the gas flow the diameter of the inlet tube 20 can be substantially less in diameter than the exhaust pipe leading to the muffler Without building up back pressure. Thus the chambers 40 surrounding the tube 2U are of maximum volume which enhances the noise suppression properties of the same and makes it possible to reduce the diameter of the casing l0 to a minimum.

At the present time it is my theory that the angularly disposed slots 42 impart a whirling action to the gases flowing along the inlet and discharge tubes 20 and 22 and that a similar action is imparted to the gases filling and passing through the chambers 4B. This whirling action of the gases is thought to be at least in part responsible for the improved sound suppression characteristic of my improved muffler. Another important feature of the present invention contributing to the silencing effectiveness of the invention resides in the double wall made up of the casing IU and the intermediate tubes 24 and 26 as at 50 and 52 in Fig. 2. IThis prevents or decreases so called shell noise. A further silencing feature resides in having a large chamber made up of the chambers 36, 32, 34 and 36 between the inlet and discharge tubes making a balanced circuit. This large chamber as located acts to obviate deceleration noises instead of agitating the same as in the usual case with a chamber in a circut, especially in the more restricted type of muier. This large chamber acts as a conducting passage between the inlet and discharge tubes 2i] and 22 opening into and leading from the chambers 32 and 3G, respectively. It also acts to expand and cool the gases and as a general diffusion chamber when the chambers 40 are perforated.

In the modified embodiment of the invention shown in Fig. 3, the outer casing 55 is oblong with semi-cylindrical portions 56 and 59 which together wih longitudinal split tubes B and 52 define tubes corresponding to the intermediate tubes 24 and 2E. Inlet and discharge tubes 64 and 66 are concentrically supported within the semi-cylindrical portions 56 and 52S. The arrangement of these tubes may be the same as in the structure shown in Fig. 1 with opposite ends thereof communicating with the chambers 68 and 10 corresponding to the chambers 34 and 36. The structure shown in Fig. 3 has the advantage that the outer casing defines in part the intermediate tubes and permits the use of two half tubes in lieu of two whole tubes as in the structure shown in Figs. l and 2.

As many changes may be found necessary in the muffler structure shown and disclosed to meet particular engine requirements Without departing from the scope of the invention, it is intended that all mattei' contained in the above description shall be interpreted as illustrative and not in a limiting sense. For the most part these changes will be confined to variations in proportions of parts, the perforations and configuration of the conductors for the gases, and the position of the associated tubes relative to each other. For example, the tubes 2B and 22 need not be concentrically located Within the tubes 24 and 26. Installation of the muffler may require that such tubes be eccentrically associated. Other changes will readily occur to those skilled in the art.

Having described my invention what I desire to protect by Letters Patent and claim is:

l. A muflier comprising a casing having inlet and discharge openings at opposite ends thereof,

an inlet conduit for conducting gases from one end of said casing and discharging the same into the interior of the casing at the opposite end thereof, a second conduit for conducting gases from the interior of said casing at the inlet end of the same to said discharge opening, and means restricting the flow of gas adjacent the inlet end, said first conduit having means for short circuiting a portion of the gas fiow therethrough into the interior of said casing adjacent the inlet end.

2. A muffler comprising a casing having lnlet and discharge openings, inlet and discharge tubes communicating with said openings, said tubes being located in said casing in offset relation and constituting conduits ior the free passage of exhaust gases from one end oi' said casing to the other, said tubes at opposite ends of said casing opening into the interior thereof, and an expansion chamber through which communication is established between said tubes, said inlet tube being of less cross-sectional area than said inlet opening, said inlet tube having means for short circuiting a portion of the gas flow therethrough into the interior of said casing adjacent the inlet end.

3. A muiiier comprising an elongated cylindrical outer casing closed at both ends except for inlet and discharge openings, inlet and discharge cylindrical tubes located within said casing and communicating with said openings, said tubes being disposed in offset relation and extending throughout substantially the length of said casing affording an unobstructive free passage of the gases therethrough, intermediate cylindrical tubes Within which said first tubes are supported and defining a chamber therewith, said intermediate tubes having an inside diameter of approximately one-half the diameter of said outer casing whereby said intermediate tubes are closely fitted thereto to provide a double wall structure for said first tubes, said first tubes being perforated along their length and at opposite ends opening into oppcsite ends of the interior of said casing.

4. A mufiier comprising an elongated casing having inlet and discharge openings at opposite ends, inlet and discharge tubes in offset rclation communicating with said openings and defining free passageways for the fiow of gases longitudinally of said casing, intermediate tubes Within which said first tubes are supported to define chambers, perforations in said first tubes communicating with said chambers, said first tubes opening into the interior of said casing at opposite ends thereof, said casing and intermediate tubes defining an expansion chamber for the gases and a conduit through which communication is effected between said first tubes.

5. A muffler comprising an elongated casing having inlet and discharge openings at opposite ends thereof, means defining passageways for the free flow of gases back and forth longitudinally of said casing between said openings, and means located adjacent said inlet opening for restricting the fiow of gases passing toward said passageways, said passageways having means for short circuiting a portion of the restricted gases from one to another thereof.

6. A multiple muiiier comprising an elongated casing having inlet and discharge openings at opposite ends thereof, offset means defining passageways for the free ow of gases from and toward said openings, an expansion chamber and passageway defined by said means and casing communicating with said means through which the gases flow in a counter-direction to the flow in said means, and means defining a passage adjacent said inlet opening for short circuiting a portion of the flow of gases.

'7. A multiple gas muffler comprising an outer casing, inlet and discharge headers therefor, means with said headers defining chambers at opposite ends of said casing, a perforated inlet tube for conducting gases longitudinally of said casing and opening into one of said chambers, a perforated discharge tube for conducting gases longitudinally of said casing leading from the other of said chambers, means defining a series of longitudinally arranged resonance chambers with each of said tubes, said last means and casing defining an elongated chamber constituting a return between said first chambers.

8. A multiple gas muffler comprising an outer casing, inlet and discharge headers therefor, means with said headers defining chambers at opposite ends of said casing, a perforated inlet tube for conducting gases longitudinally of said casing and opening into one of said chambers, a perforated discharge tube for conducting gases longitudinally of said casing leading from the other of said chambers, and means defining a series of longitudinally arranged resonance chambers Within each of said tubes, said last means and casing defining an elongated chamber constituting a return between said first chambers.

GEORGE A. KINGSLEY.