USRE21312E - Automatic regulation for engine - Google Patents

Description

Jan. 2, 1940. Y H, C. NlssEN l Re. 21,312

I AUTOMATIC RBGULATIONFOR ENGINE cooLING uEANs Original Filed Sept. 22. 1936 2 Sheets-Sheet 1 mn' mmh l l INVENTOR. HHIlIyMISSEH ATTORNEY Jan. 2, 1940.

. Original Filed Sept. 22. 1936 H. C. NISSEN AUTOMATIC REGULATION FOR ENGINE` COGL'ING MEANS 2 Sheets-Sheet 2 l lll IN VEN TOR.

A TTORNEY Reiasued Jan. 2, 1940 UNITED STATES PATENT OFFICE ,AUTOMATIQ REGULATION FOR ENGINE COOLING MEANS Harry c. Nissen, south Glastonbury, cumgusignor to United Aircraft Corporation, lut Hartford, Conn., a corporation of Delaware 14 Claims.v

This invention relates to improvements in engine cooling means, and has particular reference to cooling means for an air-cooled internal combustion engine such as commonly usedl for the l propulsion of airplanes.

An object of the invention resides in the provision of means for automatically controlling the engine cooling arrangement in accordance with the operating conditions of the engine and the condition of those factors which affect the amount and velocity of cooling air passing through the engine.'

A further object of the invention resides in the provision of means for automatically controlling 15 the engine cooling apparatus in accordance with the factors of airplane speed, engine power out-` put, and the temperature of the engine cooling air to provide desired engine temperatures under various engine operating conditions.

A still further object resides in the provision-of means ln combination with a baffled air-cooled 'engine inclosed in 'a drag reducing cowl provided with cowl flaps of means for automatically ad- .iusting the ilaps to preserve a ratio between engine temperature and flap induced drag consistent with` maximum speed and economy in operation.

Other objects and advantages will be more particularly pointed Aout hereinafter or will become apparent as the description proceeds.

In lthe accompanying drawings in which like reference numerals are used to designate similar parts throughout,there is illustrated a suitable mechanical embodiment of what is now considered to be the preferred form of the idea of the invention. The drawings, however, are for the purpose of illustration only and are not to be taken as limiting the invention the scope of which is to be measured entirely by the Ascope `of the appended claims.

40 In the drawings,

' Fig. 1 is a partly schematic elevational view of a radial air-cooled internal combustion engine of the -type commonly employed for the propulsion 0f airplanes, an engine inclosing cowl and cowl flaps being schematically shown in section;

Fig, 2 is a partly schematic perspective view of a mechanism constructed according to the idea of this invention for controlling the cooling of the engine; and

Fig. 3 is a schematic illustration of the cooling controlling mechanism showing the wiring diagrams used for the electrical portion of the device.

Referring to the drawings in detail, the nui mera] Il) generally indicates -a radial air-cooled internal combustion engine of the type commonly employed for the propulsion of airplanes. It is to-be understood, however, that the invention is not limited in ltsapplication to an engine of the particular type illustrated but may be applied to various types of air-cooled engines,

The engine in the arrangement illustrated is mounted upon a. mounting ring I2 supported upon the vehicle, vsuch as an airplane, by a suitable framework, generally indicated at I4, and is surrounded by an open ended drag reducing ring cowl, generally indicated at I6. In case of an aircraft engine as illustrated, the engine drives asuitable propeller I8 ordinarily carried upon the front end of the engine at the forward end of the airplane. Between the propeller and the en# gine the cowl IG is provided with a cooling air inlet opening 20 and at the rear end is provided with a gill opening adjacent to the re wall 22, the gill opening being controlled by a set of movable l trailing edge cowl flaps 24. In line with the engine cylinders there is provided a set of pressure bailles 26 for restricting the ilow of engine cooling air through the cowl to the finned cooling surfaces' of the engine cylinders.

For` a more detailed description of suitable pressure bailles, reference maybe had to Patent No. 2,031,541 issued February 18, 1936 to A. L. Mac- Clain, and for a detailed description of a suitable set of cowl trailing edge naps reference may be had to application Ser. No. '705,094 led January 3, 1934 by R. B. Beisel and A. L. MacClain.

The baffles 26 are effective to create a pressure differential between the coolingfalr contained in the compartment within the caw] I6 at the forward or propeller side of the-fbaliles and the air contained in the compartment within the cowl at the rear of the bailles. As the baiiles are arranged to radically restrict the ilow of cooling air through the engine, a large pressure dierential can be built up between the forward and rear cowl compartments, which pressure differential is utilized to create a high velocity in the stream of cooling air iiowing along the cooling surfaces of -the engine cylinders.

The pressure dilferential between the forward and rear cowl compartments and consequently, the velocity of the cooling air stream, canbe controlled by altering the angular position of the set of cowl flaps 24. Thus when the flaps are open the gill opening between the cowl and the fire wall 22 is increased to provide for afree exit of air from the rear cowl compartment and at the same time an induction effect is created in the air stream flowing over the outside of the cowl which 55 cowl naps and thus impose a partial vacuum upon the rear cowl compartment to materially increase the pressure differential between the iorward and re'ar compartments within the cowl. When the flaps are moved inwardly, the induction efiect of `the air stream is rst decreased, and with continued inward movement of` the ilaps the induction effect is entirely lost and the gill opening is decreased in area to a degree at which it restricts the flow of cooling air from the rear compartment. VUnder such conditions, the pressure diiierential between theviorward and rear cowl coinpartments may be reduced or, in an extreme case, the pressures may be equalized 'so that little or no' cooling o! the engine would be accomplished. From the above discussion, it is obvious that the cooling effect upon the engine of the air entering the cowl opening may be controlled within 20 extremely wide limits by varying the angular position of the set of cowl aps 24. It has been found in practice that the cooling effect of the air stream can be accurately controlled over the entire operating range of the engine to provide the .25 exact amount of cooling consistent with best engine operation and relatively minimum airplane drag at all engine operating conditions.

According to previous practice, the cowl ilaps c have ordinarily been subject only to manual control so that it has been necessary for the operator of the vehicle to watch the engine temperature indicator and adjust the cowl ilaps to obtain the best operating conditions at the temperatures indicated. As explained above, `the -present inl" vention has for its object the provision o! an automaticcontrol for engine cooling through automatic actuation of the cowl flaps to provide a more accurate and consistent relation between engine cooling requirements and the cooling eiect produced and to relieve the operator oi' the vehicle Airom -the additional burden of having to watch the engine temperatures and control the cooling arrangement accordingly. vThe objects of the invention are accomplished 4b by the provision of an automatic mechanism, generally indicated at 2l, which is made responsive -to the power output of the engine and to the pressure diilerential existing upon the opposite sides or the pressure baille system 26. This mechanism, in response to the pressure dierential and the engine horsepower.' controls a suitable device. generally indicated at In, which is eective to move the cowl ilaps 2l to various angular positions and retain them in a desired position'for the cooling eiect required under all operating conditions. While the device lli has been illustrated as a reversible electric motor and a screw jack operated thereby, a hydraulic motor or other suitable power operated device is within the scope 60 of the invention.

The control unit 2B is particularly illustrated in Fig. 2 and includes in general a pair oi' expansible metal bellows 32 and Il and an electric contact switch, generally indicated at IB, mounted in a 66 suitable casing 38.

The interior of the bellows 32 is connected by means of a suitable conduit 40 with the forward side of the baille system 26 to render the bellows ,I2 responsive to the pressure in the compartment 'Iii in the forward portion of the engine cowl. The interior oi the bellows 3l is connected by a similar conduit I2 with the interior oi an engine intake manifold 44 to render the bellows Il responsive to the horsepower output of the engine. As clearly .n illustrated in Fig. 2, the bellows and Il are tends to lower the pressure at the rear ends o! thel mounted on opposite ends of the casing Il so that they project in opposite directions into the interior oi' the casing. The inner ends oi' the bellow:

are spaced apart and are connected together by' a plvotally mounted link member or bar II which has mounted thereon intermediate its length the electric contact, generally indicated at 3l.

The contact 36 is a double contact having two contact elements 4B and 50 carried by the link or bar 46 which cooperate with an intermediate l contact 52 carried upon the free end oi' a thermostatic element 5l which, in the form of ythe invention illustrated, is a bi-metallic strip having its end opposite the contact 52 rigidly secured to a side of the casing. An electrical conduit l. u leads from one side of a battery 5l to the intermediate contact 52 and includes a manually cperable switch 80. The opposite side of the battery 5B is grounded, as indicated at 62. An electrical conduit 6l leads from the contact lli to one side A66 of the split field of a reversible electric motor BB' and a similar electric conduit In leads from the contact 48 to the opposite side 12 o! the split motor field. The current can pass from either side of the split motor eld to the rotor or the motor in a manner well known in the art and the side of the rotor opposite the field connection is grounded, as indicated at ll, to provide a complete circuit from the battery through the controlling mechanism to ground and through the ground connections back to the battery. It is obvious that, if desired. a third wire system may be substituted for the ground connections schematically illustrated in the vaccompanying drawings.

'I'he motor BB is rigidly mounted upon some iixed portion of thcengine or airplane, such as the engine supporting trame il, and is operatively'connected with the flap system 2l by suitable means, such as the screw jack 16. The opera- 4B tion oi the screw Jack is such that when the armature of the motor 8l rotates in one direction the iiaps 2l are moved outwardly, and when the motor rotates in the opposite direction the iiaps are moved inwardly. l 4l A limit switch 'Il-is provided to cle-energize the appropriate side o! the motor eld whenever the motor has moved the naps 24 to a limiting position in either direction. This limit switch..

as lmrucumriy nmscrad in ng. s, may conse veniently comprise a pivotally mounted lever member lli having one end associated by means oi' a lost motion connection with a rod l2 pivotally connected to one of the iiaps '24 and l having its opposite end in contact at oppodte sides thereoi with a pair of spring contact members 8l and 8B. The `lost motion connection between the rod 82 and the lever Il may conveniently comprise 'adjustable abutments u and lll which are effective to contact the adiacent ill) side oi the end portion of the' lever member Il when the ap 24 has'been moved to the respective limiting position. In the i'orm of the device illustrated, when the nap 24 is moved to its outer limiting position, the abutment 8l will con- Il:

tact the lower side of the end portion o! the lever member Il to swing this outer endportion upwardly about the pivot I2 and cause the opposite end ci' the lever member to bear against the spring contact member I6 and move the contact 70 member away from the respective contact M, thus breaking the contact between the battery and the side B6 of the split iield oi' the motor u. Similarly, when the iiap 2l has reached its inward limiting position, the abutment Il contacts the -28 ansia vupper side of theend portion of the lever member l0 and causes the lever member to move the spring contact member Bl away from the contact Il, thus breaking the circuit to the side 12 of the split field of the motor B8. l

'I'he operation vof the device is substantially as follows: the casing I8 is not air-tight and, therefore, subjects the bellows 32 and 34 which it contains to the pressureof the air in the cowl compartment at the rear of the engine. 'The bellows I2 is thus subject to the pressure differential between the yfront and rear cowl compartments, the pressure in the front compartment acting on the interior of the bellows, and the pressure onthe rear compartment acting upon the exterior. When the pressure in the front compartment is in excess of the pressure in the rear compartment. the bellows 32 tends to expand and move the bar lI6 to bring the contacts lil and 52 together. Bringing the contacts Il) and 52 tol gether completes the circuit through the circuit breaker and through the side B6 of the split eld of the motor 68 and rotates the motor in a d irection to closethe cowl flaps 2l.

' The bellows Il is .subject exteriorly to the pressure in the rear cowl compartment and interiorly to the pressure inthe engine intakemanifold.

' When the engine throttle is partly closed, thereby reducing the pressure in the manifold, the bellows u will be contracted so that the contact l0 will be moved toward the contact 52 with the result above stated. Ifj the engine throttle is open, or nearly open, so that the pressure within the intake manifold is high, the bellows 3l will be expanded to move the contact 5l away from the contact 52. and move the contact 48 towards the contact 52 and, under ,conditions in which the pressure diil'erentiial affecting the bellowsj2 is suillciently small and the pressure within the intake manifold Il is suillciently high, the bar 48 will be moved in a direction to bring the contacts Il and 52 together. When the contacts I8 and 52 are brought together, the circuit will be completed through the conduit 1li, the limit switch 1l, and through the side 12 of the split field ofthe motor 6l, causing the motor to rotate in a direction to open the cowl flaps 2l. Thus it lwill be seen that under conditions of a relatively low pressure differential and relatively high engine horsepower output the device will tend to open the ilaps and under the opposite conditions, that is, a relatively high pressure diiferential and relatively low engine horsepower output, the device will tend to close the cowl flaps. As the .device operates upon the resultant effect of the pressure differential and the engine horsepower output, it is also obvious that a condition of either one of these factors alone above lor below a predetermined range may be utilized to actuate the mechanism as well as the effect of both factors when acting within a predetermined 4 range.

The effect of the thermostatic element M which is responsive to the temperature of the air within the rear compartment, which is located on the downstream side of the engine with reference to the direction of cooling air ilow. is

and u together, with the result that the coni-.m1

device 28 will cause the naps to' open earlier when `the fair temperature is high. When the Yair temperature is low, the thermostatic elenifent will move the contact 52 toward the contact''l, thus delaying the opening of the cowl air temperature is low.

The limit switch il is eifectiv have reached their limiting a ar position in either direction to de-energi'telthe side of the split field of the motor tending to lrotate the motor in a direction to move the flaps further in that direction but leaving the opposite contact engaged so that upon a reversal of current the motor will be operative to move the flaps toward the opposite position. i

While the control device will tend to move the flaps with each change in the values of the pressure differential between the forward and rear flap compartments and the pressure within the intake manifold 54, when the operation of the engine reaches a stable condition such for instance as in cruising at a constant horsepower, the control devicev will move the flaps to the appropriate setting for the particular condition and will then tend to maintain the ilaps in that position. Sufficient space is provided between the contacts 5I, 52, and 48 to provide for minor variations in the conditions upon which the control is based without Iactuating the control to change the ilap setting thus. to a practical degree, eliminating the tendency of the device to "hunt when conditions are relatively stable. Suitable adjustments may obviously be provided to accommodate the device to various engine and vehicle combinations and toprovide for a desired engine operating temperature.

While there has been illustrated and described a particular mechanical arrangement of what is now considered to be the preferred form oi' the idea of the invention, it is to be understood that the invention is not limited tothe construction so illustrated and described but that such changes in the size, shape, and-'- arrangement of parts may be resorted to as come within the scope Loi the appended claims. i

Having now described the invention so that others skilled in the art may clearly understand A inders to restrict the ow of cooling air through said engine and create an air pressure differential withinsaid cowl upon opposite sides of said and close said cowl flaps, and means responsive to the pressure drop across said bailles for controlling said power operated means.

2. Irn combination with an engine having a 'plurality of heat radiating. cylinders, avcowl 4inclosing said cylinders, bailles ,between .said cylinders to restrict the flow of cooling air through said engine and create an. air pressure differential within said cowl upon opposite sides of said baiiles, and movable cowl flaps for controlling the air pressure on the low pressure side of said baiiles, power operated means effective to open and close said 'cowl flaps, and means responsive to the pressure drop across said bailles, to the power output of said engine, and to the temperv ature of the air leaving said` engine for controlling said power operated means.

3. In combination with an air cooled engine, a cowl surrounding said engine, means cooperating with said engine dividing said cowl into a high air pressure chamber and a low air pressure chamber, and means for controlling the cooling of said engine by controlling the air pressure in said low air pressure chamber, means l. responsive to the pressure diierence of the air in said cowl chambers, to the power output or said engine, and to the temperature of the cooling air leaving said engine for regulating the cooling of said engine by automatically operating said control means.

4. In combination with an air cooled engine, la cowl surrounding said engine, means cooperating with said engine dividing said cowl into a high air pressure chamber and a low air pressure chamber, and means for controlling the cooling of said engine by controlling the air pressure in said low air pressure chamber, power a operated means for operating said control means, and means responsive to the pressure diiierence of theair in said cowl chambers, to the power output oi' said engine, and to the temperature of the air in said low pressure chamber for regulating the cooling of said engine by actuating said power operated means to automatically operate said control means.

5. In combination with an air cooled engine, a cowl surrounding said engine, means cooperating with said engine dividing said cowl into a high air pressure chamber and a low air pressureV Il chamber, and means for controlling the cooling of said engine by controlling the air pressure in said low air pressure chamber comprising electrically operated means for operating said control means, and means for actuating said elec- 40 trically operated means, said means comprising a bellows responsive to the pressure diierence of the air in said cowl chambers, a bellows respon- -sive to the power output of said, engine, a switch operated by said bellows for actuating said electrically operated means, and a thermostatic device responsive to the temperature of the air Vpassing through said engine for aiecting the action of said bellows to open or close said switch. 6. In combination with an air cooled engine, a cowl surrounding said engine, means cooperating with said engine dividing said cowl intora high air pressure chamber and a low air pressure chamber, and means Vfor controlling -the cooling of said engine. by controlling the air pressure in 5 said low air pressure chamber including, a reversible electric motor for operating said cont-rol means, and means for actuating said'motor comprising a'bellows responsive to the pressure difierence o! the air in said cowl chambers, a bellows responsive to the power output oi said engine, a two-pole electric switch operated by said bellows for energizing said motor to rotate in either direction depending upon the conditions of the pressure difference and power output to which mi said bellows respond, and a thermostatic device responsive to the temperature of the air in said low pressure chamber for modifying the action of said bellows to operate said switch.

7. In combination with an air cooled engine, a :o cowl surrounding said engine, means cooperating with said engine dividing said cowl into a high yair pressure chamber and a low air pressure chamber, and a series of movable cowl ilaps' for controlling the cooling of said engine by controlling the air pressure in said low air vpressure chamber, a reversible electric motor for operating said iiaps, and means for actuating said motor comprising an element responsive to the pressure dierence ot the air in said cowl chambers, an

. elementresponsive to the power output ot said i :air pressure chamber and a low air pressure chamber, and a series of movable cowl ilaps i'or controlling the cooling oi said engine by con- ;trolling the air pressure in said low air pressure f chamber, a reversible electric motor for operating said flaps, and means for actuating said motor l0 comprising an element-responsive to the pressure diiIerenoe of the air in said cowl chambers, an element responsive to the lower output o! said engine, an element responsive to the temperature of the air in said low air pressure chamber, a 25 two-pole electric switch operated liointly or independently by said elements to energize said motor to rotate in a direction corresponding to the cooling requirements oi said engine, and a screw jack interposed between said motor and 80 said ilaps.

9. In combination with an air cooled engine, a cowl surrounding said engine, means cooperating withk said engine dividing said cowl into a high air pressure chamber and a low air pressure '35 chamber. and a series of Imovable cowl flaps for controlling the cooling of said engine by controlling the air pressure in said low air pressure chamber, a reversible electric motor for operating said flaps, and means for actuating said motor 40 comprising an element responsive to the pressure difference oi the air in said cowl chambers, an element responsive to the power output of said engine, an elementI responsive to the temperature of the air in said low air pressure chamber, a two- ,45 pole electric switch operated jointly or independently by said elements to energize said motor to rotate in a direction corresponding to the'cooling requirements o! said engine, a screw Jack ina terposed between said motor and said flaps, and 50 a limit switch interposed in the circuit between said twopole switch 'and said motor 'for de-energizing said motor to rotate further in the same direction when the cowl naps have reached their limiting position in either direction. t l0. An engine cooling system comprising in combination, means deiining a passage for a stream of air and divided into two chambers from one of which air ilows into the other. engine heat radiating means between said chambers ex- 00 posed to the air iiowing from one of said cham- -bers to the other, controlling means for governing the pressure in one of said chambers, and means responsive tothe difference in pressure between said chambers ior controlling said control- 0o ling means.

1i. An engine cooling system,l comprising in combination, means deilning a passage for a stream of air and divided into two chambers from one of which air flows into the other, heat radiating means between said chambers exposed to the air flowing from one of said chambers to the other, controlling means for governing the pressure in one oi' said chambers, means responsivetotbedifl'erenceinpressurebetweensaid" :irais chambers for controlling said controlling means, and means controlled by the temperature of the air stream leaving said heat radiating means for lvarying the controlof said controlling means.

12. An engine cooling system comprising in combination, cowling means dening a passage for a stream of air and divided into -two chambers from one of which air flows into the other, heat radiating means between said chambers exposed to the air owing from one of said chambers to the other, power-operated controlling means for governing the pressure in one of said chambers, means responsive to the difference in pressure between said chambers for controlling said controlling means, and thermally operated means responsive to the temperature oi' the air on the downstream side of said heat radiating means for aiecting the control of said power-operated means by said means responsive to diierence in pressure.

13. In combination with engine heat radiating means having heat radiating surfaces, cowling means enclosing said heat radiating means, means cooperating with said cowling means and said heat radiating means to form at least two chambers within said cowl from one of which chambers air flows over said heat radiating surfaces into the other. chamber, cowl flaps associated with said cowl, power-operated means for moving said naps for governing the pressure in one of said chambers and means responsive to variations -in vthe pressure differential between said chambers for controlling the movement ofsaid iiaps by said power-operated means.

14. In combination with engine heat radiating means having heat radiating surfaces, cowling `means enclosingcr said heat. radiating means,

for varying the control of said controlling means.

"HARRY C. NISBEN.

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