US2687124A

US2687124A - Preheat apparatus for small engines

Info

Publication number: US2687124A
Application number: US288994A
Authority: US
Inventors: Franz J Neugebauer; Hans O Berkner
Original assignee: US Air Force
Current assignee: US Air Force
Priority date: 1952-05-20
Filing date: 1952-05-20
Publication date: 1954-08-24
Anticipated expiration: 1971-08-24

Description

Aug 24 1954 F. J. NEUGEBAUER x-:TAL 2,687,124

PREHEAT APPARATUS FOR SMALL ENGINES Filed May 20, 1952 4 Sheets-Sheet l Aug- 24 1954 F. J. NEUGEBAUER ETAL 2,687,124

FREI-IEAT APPARATUS FOR SMALL ENGINES Filed May 20, 1952 4 Sheets-Sheet 2 g YIII'IIHIIA- BY MMM-e M A11g- 24, 1954 F. x. NEUGEBAUER ETAL 2,687,124

PREHEAT APPARATUS FOR SMALL ENGINES Filed May 20,` 1952 4 sheets-sheet s l AUS 24, 1954 F. J. NEUGEBAUER ETAL 2,687,124

PREHEAT APPARATUS FOR SMALL ENGINES Filed May 20, 1952 4 Sheets-,Sheet 4 F7701. fy-

Patented Aug. 24, 1954 'UNITED STATES PATENT OFFICE PREHEAT APPARATUS FOR SMALL ENGINES Franz J. Neugebauer, Schenectady, N. Y., and Hans i0. Berkner, Dayton, Ohio, assignors to the United States of America as represented by the Secretary of the Air Force Application May 20, 1952, Serial No. 288,994

8 Claims. (Cl. 12S-142.5)

(Granted under The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a device for preheating small engines during cold temperatures without resorting to an external power source.

In the subject invention a stack and burner is utilized in combination with an engine, the burner creating a very high temperature gas in the stack. This high temperature is necessary for generating a substantial draft in the stack; but this high temperature is too great for the equipment to be preheated to withstand. To overcome this diiiiculty, the subject invention incorporates heat exchangers for conducting heat from the stack to the engine elements to be heated. The amount of heat conducted by the heat exchangers from the stack depends upon the length, crosssectional area, and the heat conductivity of the material of which the heat exchangers are made. The material and dimensions for designing the heat exchangers can be selected within a wide range to conduct a heat temperature suitable for the engine elements in spite of the high temperature in the stack.

Therefore, an object of the invention is to provide a simple preheating device for engines, which device does not depend on an external source for power.

A further object of this invention is to provide means for conducting heat from a high temperature source to the components of an engine at a satisfactory operating temperature.

These and other objects will become more apparent from the accompanying drawings and specifications wherein similar parts have like numbers and wherein:

Figure l shows the arrangement of a single cylinder gasoline engine in combination with a stack burner and heat exchanger.

Figures 2 and 3 are views showing the design of heat exchangers used in the device of Figure 1.

Figure 4 shows a device for preheating the carburetor air.

Figures 5 and 6 show the subject invention adapted to a two-cylinder engine.

Figures 7 and 8 show a method of heating an oil pan.

Referring to Figures 1-3 a single cylinder en-` gine is generally designated as I0 with a vertical stack I2 open at both ends mounted along side thereof. The burner arrangement III is located within the lower portion of the stack I2. The stack I2 is provided with openings I5 for the Title 35, U. S. Code (1952),

sec. 266) entrance of air to the burner. The burner Id may be automatically operated to turn it on and olf by an automatic means such as a spark plug and magneto arrangement I3. Immediately above the burner lf3 is mounted a heat exchanger `Iii for heating the bearings and the piston ofthe engine by heat convection and radiation. The heat exchanger I6 is in the form of an L but may be any other desired shape as the design requirements may require. The center portion I9 of the L is solid and may be of any convenient cross sectional area depending on the rate of heat conduction desired. From each end of the solid portion I9 extend the elements or fins Il, one end extending into the stack I2 and the other end above the oil level in the crankcase I8. An additional heat exchanger 20 is located at the carburetor 22 of the engine. One end of this heat exchanger enters the carburetor andthe other end extends into the stack- I2. A manifold 23 surrounds the stack l2 and is connected to the carburetor 22 for heating the air entering into the carburetor.

The temperature above the burner may be over l500 F. which is too great for the engine and oil pan to withstand, their maximum being about 400 F. to 500 F. The material and dimensions of the heat exchangers must be selected so that during the heating time, the temperature of the heat exchangers do not exceed the temperature limit of the lubricant or engine components. Ii the amount of heat conducted is required to be high, then the material of the heat exchangers should be of copper and the solid part between the ns should be of a large cross-sectional area and of short length. In order to cut down the rate of heat conduction the heat exchangers may be made of aluminum inside the oil pan and of copper or steel inside the stack and of a larger length center portion I9 having a smaller crosssectional area and by including a circumferential groove 2i in the solid center portion. The burner is a multi-fuel burner which is able to operate on gasoline as Well as kerosene, jet fuel or diesel fuel.

In operation the burner I4 may be ignited either automatically or by hand, preferably automatically by a spark plug and magneto arrangement. The burner will generate a very high temperature in order to create a large draft in the stack in an upward direction resulting in a thermosiphon. The heat will be conducted from the stack to the oil in the crankcase and carburetor by the heat exchangers. The material and dimensions of the heat exchangers I6 and 20 are such as to conduct only a predetermined heat to the engine elements. When the carburetor and the oil in the crankcase reach a predetermined temperature value the burner can be automatically turned off and the engine can then be started.

Referring to Fig. 4 the carburetor 22 is so disposed as to open into the stack l2 at 2l so that it might be possible to preheat the carburetor air during the operation of the engine during which time the burner is not in operation. The exhaust pipe 2li extends through the stack I2. Mounted on the exhaust pipe are ns 25 located Within the stack for heating the air passing over the pipe. Butterfly valves 25 and 2S (Figure 1) are provided in the upper portion and lower portion of the stack respectively for controlling the air flow for different heating and operating conditions. An adjustable ring 30 (Figure 1) is adapted to cover the air holes l5, and also provides a means for controlling the air flow for diierent heat and operating conditions. Whereupon by adjusting the butterfly valves 26 and 28, and the ring l, during operation of the engine, the air passing over the heated fins attached to the exhaust 2li will be heated and carried to the carburetor to obtain better performance of the carburetor during engine operation.

Referring to Figures and 6 in which a twocylinder diesel engine is shown, the heating gas from the burner iii is guided along the oil pan I8 which in this embodiment contains the heat exchanger 32. The hot gas is led through hollow spaces 34 in the covers, along heating channeh= 36 in the crankcase, and along pipes (it to the stack t0. The pipes 33 can be arranged close to the engine cylinder and to the fuel injection pump to heat them by convection and by radiation. Since the heating gas ymust pass through horizontal ducts, in this case, it might be difficult to start the stack from cold condition. For this reason a bypass 42 is provided to extend from the burner to the stack to generate an initial draft by guiding the small amount of hot gases immediately from the burner to the stack di).

Figures 7 and 8 show another method of heating an oil pan in a crankcase. The oil pan is designated as 5i! and is an aluminum casting having integral fins 52 and integral tubular mountings 53 therewith. The heat exchangers consist of one or more finned pipes 54 having central openings 55 and partitions 5l' therein. The pipes are made of heat resistant steel which has a low heat conductivity factor. The circumference of the pipes is provided with grooves 56 to further decrease the rate of heat conduction.

In operation the heat passes through the opening 55 of the finned or fluted pipes 54, up through the partitions 5l, to the oil pan 50 so as to heat the oil therein to the desired temperature.

By the several embodiments shown of the invention a simple and compact device for heating small engines is provided. The simple burner does not need an external source of power, such as a battery, for its operation, and furthermore does not merely rely on gasoline but is designed as a multifuel burner.

It is apparent that specific embodiments shown above have been given by way of illustration and not by way of limitation and that the structures above described are subject to wide variationv and modication without departing from the scope or intent of the invention, all of which variations and modications are to be considered as equivalents and be included Within the scope of the present invention.

We claim: l 1. In combination with an engine having an oil pan and carburetor, preheat equipment comprising a 'vertical stack connected vadjacent to said engine, said stack being open at both ends for the passage of air therethrough, a burner located in the lower portion of said stack for heating the air and creating a thermo-Siphon to move air lin an upward direction, a rst heat exchanger having one element of low heat conductivity material extending into said stack and another element of high heat conductivity extending into said oil pan, a second heat exchanger having one element of low heat conductivity material extending into said stack and another element of high heat conductivity connected to said carburetor, a third heat exchanger comprising a manifold .surrounding the stack for heating the air entering into said carburetor, the elements of the first and second heat exchangers are connected together by solid central portions having reduced cross-sectional areas which may be varied to control the amount of heat conduction therethrough.

2. The combination as in claim 1, wherein, the elements of the rst and second heat exchangers are comprised of fins at one end which extend into the path of the hot gases in said stack, and iins at the other end which contact the engine elements to be preheated.

3. The combination as in claim 1, wherein the elements of two of the said heat exchangers comprise fins at each end of the solid central portion, the one end extending into the stack being made of steel and the other end extending into said engine adjacent to the parts to be preheated being made of aluminum.

4. 1n combination with an engine having an oil pan and carburetor, preheating equipment comprising, a stack open at both ends connected adjacent to said engine and having a combustion chamber therein provided with air openings, and an adjustable ring covering said air openings regulating air flow therethrough, a multifuel burner in the lower portion of said stack, a finned heat exchanger in the path of the hot gases in said stack and in contact with said oil pan, the said heat exchanger having a groove therein for controlling the amount of heat conducted from the stack to said oil pan.

5. In combination with an engine having an oil pan and carburetor, preheating equipment comprising, a stack open at both ends connected adjacent to said engine` and having a combustion chamber therein provided with air openings,

and an adjustable ri-ng covering said air open-- ings regulating'air now therethrough, a multiiuel burner in the lower portion of said` stack, a` finned heatexchanger inthe pathof the hot gases in said stack and in contact with said oilv pan, the said heat exchanger provided with means for controllingY the amount of heat conducted from the stack to said-'oil pan.

6'; InL combination withV an engine and its components, preheating equipment comprisingmeans.

adjacent to said engine for generating the source of heat, finned heatl exchangersifor conducting a controlled amount of heat. to said components,

said heat exchangers comprising ns at one end.

of low heat conductivity material contacting'the source of heat. and ns at the other end of high;

heat conductivity material contacting said components.

7. In combination with an engine andr its components, preheating. equipment comprising means:

and means for controlling the amount of heat 5 applied to the ns at one end, for controlling the amount of heat conducted tothe ns at the other end which are in contact with components of the engine.

8. In combination with an engine having an oil 10 1602736 pan and carburetor, preheating equipment comprising means adjacent to said engine for generating a source of heat, finned heat exchangers for conducting a controlled amount of heat to said oil pan and carburetor, said heat exchangers comprising fins at each end of the heat exchanger, the amount of heat being controlled by the portion between the iins having a predetermined cross-sectional area and length for conducting the amount of heat desired.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 904,267 Korting et al Nov. 17, 1908 Woolson Oct. 12, 1926 2,122,585 Pollack et al July 5, 1938 FOREIGN PATENTS Number Country Date 582,472 Germany Aug. 15, 1933 864,250 France Jan. 13, 1941