US2336800A - Throttle control device - Google Patents

Description

E. F. PIERCE THROTTLE CONTROL DEVICE Filed July 15, 1941 Dec; 14, 1943.

INVENTOR Era/d f. Pie rue.

ATTORNEY Patented Dec. 14, 1943 THROTTLE coN'raoL nsvicn Erold F. Pierce, Pines Lake, N. .17., assignor to Wright Aeronautical Corporation, a corporation of New York Applicaiioniuiy 15, 1941, Serial No. 402,455

4 Claims.

This invention relates to controls for internal combustion engines and is particularly concerned with a device adapted to govern an engine to constant power output by causing the engine throttle to be responsive in its position to the liquid fuel how of the engine.

Although the invention is applicable to internal combustion engines in general, it is particularly applicable to aircraft engines and the showing in the drawing includes the device as applied to a radial cylinder air-cooled aircraft engine. Various attempts have been made to con trol engine power automatically by maintaining constant manifold pressure but such constant pressure is not necessarily a true criterion. for holding power constant unless engine R. P. M. is constant and unless controls are imposed in the system to compensate for temperature, atmospheric pressure, and exhaust back pressure variations. Accordingly, it is an object of this invention to control engine power by maintaining constant the amount of liquid fuel fed to the engine carburetor or to any other fuel-air proportioning device which may be used. A further object of the invention is to make the engine throttle sensitive to variations in liquid fuel flow to the engine and further, to provide adjustable means by which the amount of fuel flow to the engine may be regulated, thus setting the engine for different power outputs.

Further objects of the invention will become apparent in reading the annexed detailed description in connection with the drawing, in which:

Fig. 1 is a section through the control device of the invention, with auxiliary apparatus indicated diagrammatically; and

2 is a side elevation of an engine with the control apparatus installed thereon.

Referring first to Fig. 2, I show an aircraft t ,e engine comprising a crankcase it containing acrankshaft ll whose front end comprises a propeller shaft l2 and whose rear end drives a supercharger impeller iii, the latter being supplied with a fuel-air mixture from a carburetor id and delivering its compressed charge through an intake manifold IE to an engine cylinder it. The carburetor it is provided with the usual throttle having a throttle lever ll connected through a link It with a servomotor it. At the bottom of the servomotor ill is a manual throttle adjusting piston is connected through a bellcrank 2i and an operating rod 22 to the usual pilots throttle quadrant, not shown. The servomotor i9 is energized by a control unit 24 secured to the rear of the engine through a Venturi member 25 through which liquid fuel passes from a feed line 26 to a pipe 21 delivering to the carburetor id. The devices I9, 2 3 and 25 are shown in larger scale in Fig. 1. It may be here noted. that the servomotor i9 is of a type similar to that disclosed in my co-pending application entitled Hydraulic throttle control, bearing Serial No. 293,207, and filed September 2, 1939. The servomotor, briefly, comprises a cylinder 30 in which a piston Si is slidable, said piston being directly connected through a piston rod 32 to the link IS. A lower piston 3t is disposed in the cylinder at, this being connected to the manual throttle rod 29 which rod, within the cylinder housing, comprises a shut off valve at $5 for hydraulic fluid lines 36 and 31 leading respectively to ports in the cylinder wall above and below the piston 3i. The piston 34 is further provided with a check valve 38 and the cylinder wall is provided with a bypass 4i) connecting the top and bottom of the cylinder but masked at its lower end by the piston 34 when the latter is in its lowermost position. When the piston rod 2% is in its bottom position, the piston Si is moved up and down by admission of hydraulic fluid through one or the other of the passages 36 or 31. If manual throttle operation is desired, the piston 34 is moved up until it abuts the bottom of the piston 3!, liquid between the pistons evacuating through a check valve 38 whereupon the two pistons are locked together hydraulically for manual throttle control until such tim as the piston 34 is moved to its lowest position where upon automatic throttle operation may again take place.

The Venturi housing 25 includes a Venturi throat 42 which is connected through a conduit 43 to a cavity 44 defined in a chamber it: by a yielding diaphragm 46 and a'rigid partition ll, the latter two elements being sealed to the walls of the chamber. Venturi static pressure is led from the large bore of the Venturi through a conduit :38 to a cavity 49 in the chamber 45 defined by the partition ll and by a yielding diaphragm 58 secured to the walls of the chamber. Venturi static pressure is balanced by a spring ill in a cavity 52 below the cavity t9, the pressure in said cavity 52 being substantially atmospheric. This atmospheric pressure is conducted through a conduit 53 to a cavity 55 defined between the upper wall of the diaphragm 36 and the lower Wall of a yielding diaphragm 55. The latter d fines with the top of the chamber it a cavity 56 which is subjected to less than atmospheric pressure by a vacuum pump 57 communicating, through an orifice 53, with said cavity 56 through a pipe 68. Branching from the pipe it is a gauge ti and a vacuum relief valve assembly 652, the latter comprising a valve 63 loaded by a spring E i whose compression may be adjusted by acontrol 65 available to the pilot. By the use of the control 65 the pilot may preset any desired vacuum on the gauge 6! which latter may be calibrated in power units or with any appropriate indicia.

which is connected into the normal pressure luf bricating system of the engine. The bore 68 is further provided with scaveng ports 79 -communicating with a pipe H leading to-the engine oil sump. The bore 68 is further provided with oil ports 13 and 14 connected respectivelywith the servomotor conduits 36 and 31.

The valve Bland the associated ports :are so arranged that when the valve is in a central position, the ports Hand 14 are closed, holding the servomotor l9 stationary. If the valve 6'! is raised, pressure oil passes from the port 69 to the port 13, thereby directing pressure oil to the bottom of the throttle operating piston 3! to cause opening of the engine throttle I l. Oil passing from above the piston 3! is carried to the engine sump through the ports 14 and 18. If the valve stem 6'! is lowered, pressure oil passes from the port 6'! to the port 14 thus closing the engine throttle, while scavenged oil passes from below the piston 3| through the port 73 to the drain port 10. Although the stem 66 passes through an opening in the partition 41, a fairly close fit is naturally provided so that the leakage path from chamber 48 to chamber 44 around the stemBB is restricted as compared to the siZe of passageways 43 and 48. Accordingly, the pressures in chambers 44 and 49 are proportional to the Venturi suction and Venturi barrel pressures respectively.

Referring now to the diaphragm and Venturi operation, it will be seen that Venturi static pressure is balanced by the spring and that a balance obtains between the cavity 44 connected with Under some conditions of operation, automatic power regulation may not be desired in which case the pilot may take the control of the engine away from the devices 24 and 25 by manipulating the manual throttle rather than by manipulating the adjustment knob 65.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1. Constant power control means for an internal combustion engine including a carburetor having a throttle comprising a venturi in a liquid the Venturi throat and the calibrated low pressure existing in the cavity 55, so long as the valve 6'! is neutral. Should the flow of fuel to the engine increase, there will be a lower pressure at the Venturi throat which is transmitted to the cavity 44, thereby unbalancing the diaphragm system and lowering the valve 61 to cause closure of the engine throttle. Engine throttle closure of course will decrease the demand for liquid fuel and when the liquid fuel flow diminishes through the venturi to the necessary extent, the engine throttle will stabilize in a new position. Should the flow of fuel through the venturi decrease for any reason, the increased plessilre'in the cavity 44 resultin from such decrease will raise the valve 61 thereby opening the throttle I 7 through the operation of the servomotor to increase the fuel demand.

When it is desired to alter engine power, change in degree of vacuum in the cavity will cause unbalance in pressure between the cavities 56 and M3 and throttle opening or closing will follow in the same manner as described above. Although an adjustable vacuum regulating system is shown as being a convenient and practical one, any other sort of yieldable adjustment could beutilized, such as a spring, or a pneumatic or hydraulic pressure system. i

Since the amount of liquid fuel consumed by the engine is a reasonably true criterion of engine power, assuming that the carburetor properly proportions the liquid fuel and air, it will be readily appreciated that the reading of the gauge 6| will be a proper indication of power output and furthermore, that the adjusting knob will be an adequate means to preset any desired engine power.

fuel feed line to the carburetor, a diaphragm system responsive to the Venturi pressure drop, controllable elastic means to adjust the balance point of the diaphragm'system, and means responsive to diaphragm movement to adjust the carburetor throttle in an opening direction in response to a decrease of said Venturi pressure'drop and in a closing direction in response to an increase of said Venturi pressure drop.

2. In a power control for an internal combustion engine including a-throttle and a fuel supply line, a venturi in said line, a housing including a chamber therein, a partition across said chamber, yielding diaphragms in the chamber on opposite sides of said partition and defining therewith two cavities, means connecting one cavity with the Venturi throat, means connecting the other cavity with the Venturi barrel, a stem connecting said diaphragms, a servo valve operatively connected to said stem, manually adjustable elastic means opposing the Venturi forces imposed on said diaphragms, and a motor actuated by servo valve movements operatively connected to the engine throttle.

3. In a power control'for an internal combustion engine including a fuel-air proportioning mechanism, a fuel feed line to the mechanism including a venturi, a chamber having partitions dividing same into a plurality of cavities of said partitions being movable jointly, conduits from the venturi to certain of said cavities, means to maintain in another of said cavities a uniform pressure tending to counteract the Venturi pressure, unbalance between the uniformand Venturi pressures causing movement of said jointly movable partitions, an engine air throttle, means actuated by changes in position of said jointly movable partitions to alter the setting of said throttle, and means to adjust said uniform pressure.

4. In a power control system for an internal combustion engine, a carburetor having a throttle and a fuel feed line, a venturi in said feed line, a housing including a chamber therein, a partition across said chamber, yielding diaphragms in the chamber on opposite sides of said partition and defining therewith two cavities, means connecting one cavity with the Venturi throat, means connecting the other cavitywith the Venturi barrel, a stem connecting said diaphragms, a servo valve operatively connected to said stem, a motor actuated by servo valve movements operatively connected to said throttle, and elastic means opposing the Venturi forces imposed on said diaphragms, said elastic means including an adjustable source of fluid pressure;

. EROLD F. PIERCE.

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