US3404731A

US3404731A - Combined exhaust silencer and heat exchanger

Info

Publication number: US3404731A
Application number: US564593A
Authority: US
Inventors: Paul A Cushman
Original assignee: Paul A. Cushman
Current assignee: PAUL A CUSHMAN
Priority date: 1966-07-12
Filing date: 1966-07-12
Publication date: 1968-10-08
Anticipated expiration: 1985-10-08

Description

Get. 8, 1968 P. A. CUSHMAN COMBINED EXHAUST SILENCER AND HEAT EXCHANGER Filed July 12, 1966 EXHAUST FLOW I? 64 K n 30 2e o l-sea IZ i 0 L 20 0 O ,4\ &-|0 22\ o\22 28 l 38 o] 3oN d m 64 eo 56 g I6 68 Fig.3

INVENTOR.

PAUL A. CUSH MAN United States Patent 3,404,731 COMBINED EXHAUST SILENCER AND HEAT 1 EXCHANGER Paul A. Cushmau, 6791 Alamo Way, San Diego, Calif. 92115 Filed July 12, 1966, Ser. No. 564,593 4 Claims. (Cl. 16551) ABSTRACT OF THE DISCLOSURE This is a combined exhaust mufiier and heat exchanger, for use with an internal combustion engine, ordinarily on a boat or other vehicle, to suppress noise while providing for a hot water supply for the boat or other vehicle. The bafiies are flat, transverse, tightly wound, spiral coils of pipe in spaced relation defining baflie chambers therebetween and the spirals feed into manifolds both disposed longitudinally in an open channel running axially of the casing.

The present invention relates to exhaust gas treatment and specifically to an exhaust silencer incorporating a heat exchanger. While adaptable to a variety of engines and installations, the unit is particularly elfective when used on a boat, wherein the exhaust is composed of a mixture of engine exhaust gases and water from the engine cooling system. In addition to suppressing exhaust noise the unit will provide a supply of hot water, which is heated rapidly to a useful temperature but cannot boil, since the exhaust heat is held below boiling point by the water in the exhaust.

Conventional heat exchangers utilizing engine exhaust are usually in the form of jackets around exhaust pipes, or have heat collecting elements immersed in the gas flow. In the unit disclosed herein the exhaust is conducted through a casing in which coiled water pipes are arranged to form silencing baflles and are connected together in a novel manner for maximum flow efliciency with a'variety of possible hot water system connections, the piping assembly being self-supporting and providing supports for the unit if required.

The unit, its structure and a typical installation are illustrated in the drawings, in which:

FIGURE 1 is a top plan view of the unit with one half of the casing removed;

FIGURE 2 is a sectional view taken on line 22 of FIGURE 1, with the casing complete; and

FIGURE 3 is a diagram of a typical exhaust and hot Water system.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.

The unit comprises a casing having a cylindrical expansion chamber 12, with a reduced diameter inlet 14 at one end and a corresponding outlet 16 at the other end. Casing 10 is split diametrically along its length into two identical halves 18A and 18B, which have confronting flanges 20 along both sides and are secured together by bolts 22, or similar means. Any suitable sealant or gasket may be used between the flanges to prevent leakage.

Along one side of the axis of expansion chamber 12 is a manifold pipe 24 having elbow-

like end connections

26 and 28 projecting outwardly through the casing, the flanges 20 having arched portions 30 to fit closely around and secure the end connections. Along the other side of the axis of expansion chamber 12 is a similar manifold pipe 34, having outwardly projecting

end connections

36 and 38. Spaced longitudinally in the expansion chamber and surrounding the manifold pipes are heat exchanger coils 40 of small diameter tubing. Each coil is of spiral form in a plane substantially perpendicular to the axis of casing 10, the inner end 42 of each coil being connected to one manifold pipe and the outer end having an extension 44 which passes across a portion of the spiral to the other manifold pipe. As illustrated the outer end extension 44 of one coil 40 is connected to manifold pipe 24, while the outer end of the next adjacent coil is connected to the manifold pipe 34. The coils or spirals are alternated in this manner so that flow is reversed from outside to inside in every other coil, ensuring more efficient scavenging and transfer of heat. With the ends of both of the manifold pipes securely held between the halves of the casing and the coils fixed to the manifold pipes, the entire heat exchanger piping assembly is held in proper alignment Without additional supports. The

end connections of the manifold pipes are indicated as being screw threaded, but any suitable pipe connecting means may be used.

The spaces between the coils 40 comprise baflle chambers 46 which provide the noise suppression action. Although the coils do not form solid walls there are effective chambers formed which are generally disc-shaped, extending transversely of the casing, and these chambers allow multiple expansions of the pressure pulses in the exhaust flow and have been found to provide a con-siderable degree of sound suppression, the basic technique being well known in some types of silencers. The coiled pipe may be much more closely spaced than illustrated in the drawing to provide a more solid wall, each coil being as large as possible tominimize the space between the outside of the coil and the casing wall. The complete assembly has an open central passage 48, approximately the same cross sectional area as the exhaust inlet and outlet to avoid back pressure, with longitudinally spaced, laterally extending bafile chambers 46. The

manifold pipes

24 and 34 extend along opposite sides of the central passage 48 and cause a minimum of obstruction to the exhaust flow.

In a typical installation, as shown in FIGURE 3, the unit is installed at a convenient position in the engine exhaust pipe, with an inlet pipe 50 inserted in inlet 14 and an outlet pipe 52 in outlet 16. Sleeve type gaskets or O-rings may be used around the exhaust pipe sections to ensure good seals when the casing halves are clamped together. If support is necessary, suitable brackets 54 or the like may be attached directly to two or more of the manifold pipe end connections as indicated in broken line.

The hot water system includes a tank 56 in which hot Water is stored, a faucet 58, or similar outlet being provided for convenient use. From the lower end of tank 56 a supply pipe 60 leads to end connection 26 and a return pipe 62 leads from end connection 38 back to the top of the tank. By using diagonally opposed end connections a maximum circulation of water is obtained. However, any pair of end connections may be used depending on the installed position of the unit and the flow involved. The

unused end connections

28 and 36 are sealed by blank end caps 64. For a high flow rate all four end connections may be used by adding supply and

return pipes

66 and 68, respectively, with appropriate connections to a common or separate storage tanks or delivery points.

Since the flow characteristics of the unit are substantially symmetrical about the axis it can be installed with the exhaust entering from either end and the hot water circuit made to any convenient connections.

In a boat the mixing of water with the exhaust gases prevents the exhaust temperature from rising above the boiling point of water, so the water in the hot water system will not boil and cause dangerous pressures to build up. For maximum heat exchange conductivityand corrosion resistance, the piping is preferably of stainless steel or similar material. However, since the exhaust temperature is maintained at a reasonably low level, the casing 10 can be made of a more economical material, such as glass fiber reinforced plastic, which serves as an insulator to retain the heat.

By making the casing in two halves the unit is easily dismantled for cleaning and servicing. With one half of the casing removed, as in FIGURE 1, the entire pipe assembly can be lifted out as a unit to facilitate cleaning of the coils and testing for leaks. The inner surfaces of the casing are then completely unobstructed and any deposits thereon are easily removed.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawing are to be considered as merely illustrative rather than limiting.

I claim:

1. A combined exhaust silencer and heat exchanger, comprising:

a substantially cylindrical casing enclosing a chamber and having an inlet and an outlet at opposite ends thereof;

a pair of manifold pipes extending longitudinally of said casing and having end connections externally of the casing;

a plurality of spirally coiled pipes spaced longitudinally in said chamber and substantially normal to the axis of the casing, each of said coiled pipes having one end connected to one of said manifold pipes and the other end to the other manifold pipe;

the central portions of said coiled pipes being open and defining an axial exhaust conducting passage, both said manifold pipes being in said passage;

and said coiled pipes being generally flat spirals defining therebetween generally disc-shaped noise suppressing bafile chambers extending transversely of the casing, the inner and outer ends of said coiled pipes being alternately connected to the same manifold pipes so that fiow is from the outside to inside in every second spiral and from inside to outside in the intervening spirals.

2. The structure of claim 1, wherein each of said mani fold pipes has end connections at both ends thereof for connection to a fluid system, said end connections extending through and being secured in the sides of said casing, whereby the manifold and coiled pipe assembly is entirely supported by the end connections.

3. The structure of claim 2, wherein said casing is composed of two longitudinally separated portions, said end connections extending between the portions'andsaid casing having means for clamping the portions together upon said end connections.

4. A combined exhaust silencer and heat exchanger,

comprising:

a substantially cylindrical casing enclosing a "chamber and having an inlet and an outlet at opposite ends thereof;

a pair of manifold pipes secured in said chamber along opposite sides of the axis thereof and having end connections externally of the casing;

the central portions of said coiled pipes being open and defining an axial exhaust conducting passage;

the spaces between said coiled pipes constituting noise suppressing baffie chambers;

each of said manifold pipes having end connections at both ends thereof for connection to a fluid system, said end connections extending through andbeing secured in the sides of said casing, whereby the manifold and coiled pipe assembly is entirely supported by the end connections; and

said casing being composed of two longitudinally separated portions, said end connections extending between the portions and said casing having means for clamping the portions together upon said end connections.

References Cited UNITED STATES PATENTS 389,900 9/1888 Pratt et al 165-163 676,770 6/1901 Rayner 165-163 X 1,049,014 12/1912 Weir 165-163 X 1,391,709 9/1921 Wood et al. 165-52 1,646,786 10/1927 Eatinger 165-41 1,726,531 9/1929 Andel 165-41 2,143,287 1/1939 Smith 165-163 3,324,533 6/1967 Watteau 165-134 X 2,027,886 1/1936 Shull 165-175 X 2,429,663 10/1947 Beatty 165-175 X FOREIGN PATENTS 452,821 11/ 1927 Germany.

ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, Assistant Examiner.