US2780211A - Engine fuel delivery control - Google Patents

Description

United States Patent ENGINE FUEL DELIVERY CONTROL John Hans Davids, Beloit, Wis., assignor to Fairbanks, Morse & Co., Chicago, 111., a corporation of Illinois Application July 20, 1955, Serial No. 523,147

8 Claims. (Cl. 123-103) This invention relates to improvements in the control of fuel delivery to internal combustion engines, and has particular reference to a novel method and manner of regulating fuel supply to engines operable on gaseous fuels.

Engines adapted for operation on gaseous fuels such as propane and the like, are now in relatively wide use with oil drilling rigs and the like, as for operating slush pumps, drill line hoists and other rig equipment. In connection with engines in such use, gaseous fuel is supplied from a fuel source maintained under a substantially constant predetermined supply pressure, with engine delivery of fuel controlled by a throttle valve positioned by an engine driven governor operating responsively to and in accordance with engine torque output or loading. The governor of the type usually employed for controlling the fueling of these engines, is adjustable to and between adjustment settings corresponding to high and low engine speeds, whereby to effect conditioning of the governor for proper load response under various engine speeds.

In the operation of gas engines having a fueling system of the character above indicated, it is found in practice and particularly in connection with drill rig operation, that the operator usually effects governor adjustment to its high speed setting upon any load application to the engine irrespective of whether the applied load is light, intermediate or at the maximum of engine capacity. Moreover, such adjustment generally is effected quite rapidly, as by a quick throw of the governor adjustment to the maximum or high speed setting. As a result, the immediate response of the governor to the applied load, is such as to open the throttle valve to its full open positionor at least to an open position greatly in excess of that required for effective fueling of the engine in its acceleration to the speed necessary to carry the then applied load. Consequently, gaseous fuel delivery to the engine is in such quantity as to result in over-rich fuel mixtures which are difiicult if not impossible to ignite. Moreover, even though localized ignition may occur as in the immediate region of the ignition device in the cylinder, as a spark plug for example, the remainder of the over-rich mixture usually will quench the initial flame, thus precluding fuel combustion. The result, of course, is that the engine ceases operating or stalls, requin'ng the operator to restart the engine'and make another attempt to place it in operation under the desired load. Very often in drill rig operation, such stalling condition is produced at critical times. Hence, it is highly important to provide a fuel control system which will avoid the difliculty hereinabove described, and which will assure proper engine fueling under all conditions.

Accordingly, the principal objective of the present invention is to provide in connection with a governor operated throttle 'valve fuel system of the character indicated, control means acting automatically to limit or restrict governor opening actuation of the throttle valve in "ice a'manner and to a degree precluding non-ignitable over rich fueling of the engine.

Another object is to provide automatic control means as indicated, which operates in direct accordance with engine speed, and is in such controlling relation to the governor operated throttle valve provision as to permit governor opening of the valve upon load application, to an extent required for engine acceleration to the speed necessary to carry the applied load.

Other objects and advantages of the invention will appear from the following description of an exemplary embodiment thereof illustrated in the accompanying drawing, wherein the single figure of the drawing discloses diagrammatically, an effective form of fuel control system according to the invention.

Referring to the drawing, only so much of an internal combustion engine as is necessary to a full understanding of the present invention, is here shown in schematic manner. The portion of the engine shown includes engine cylinders 10, the engine crankshaft indicated by the broken line 11 representing the crankshaft axis, a fuel intake manifold 12 for cylinder delivery of gaseous fuel, and a scavenging and charging air supply manifold 14 for cylinder supply of air under pressure established by a suitable air compressor or blower 15. The compressor is driven from the engine crankshaft, as indicated by the broken line drive connection 16, and is of a type or character to produce and maintain compressed air in the manifold 14 at a pressure directly proportional to engine speed.

A fuel supply conduit 18 containing a fuel control or fuel throttle device 19 hereinafter to be described, connects the engine fuel manifold 12 with a source of gaseous fuel, as the supply tank 20, wherein gaseous fuel is maintained under a substantially constant, determined supply pressure, as for example, a pressure of 40 pounds per square inch. Included in conduit 18 between the source and the device 19, are a main gas valve 21 and a suitable pressure reducer or regulator 22 which may be adjusted to determine the pressure of the fuel delivered to the control device 19 at any desired value, say for example, about 30 pounds per square inch.

The throttle device 19 embodies a pivotal throttle valve 23 arranged in the path of gaseous fuel flow through the device, the device functioning through the valve element, as a variable orifice for throttling the constant pressure gas supply in line 18 to a pressure and rate of feed on the discharge side of the valve, determined by the position of the valve. Valve 23 is under control of an engine operated speed-settable governor 26 of suitable type, driven from the engine crankshaft as indicated by the broken line drive connection 27. In the present arrangement, the governor is operatively connected to the inter mediate portion of valve actuating lever 28 by a yieldable link structure indicated diagrammatically at 30 as comprising a governor positioned cylinder 31, an element 32 connected to valve lever 28 and having a head 34 slidable in the cylinder, and a compression spring 35 in the cylinder acting against head 34. Spring 35 is of a capacity to retain the head 34 against cylinder flange 36 during governor operation of the link structure to move throttle valve 23 in the opening direction, provided the valve or its lever 28 is not constrained against such displacement. However, in restraint of valve opening movement (as will be hereinafter described), the spring will yield to allow governor operation of the cylinder 31 in the valve-opening direction, while the element 32 remains stationary. Also in governor operation in the valveclosing direction, the link structure will be effective upon engagement of the cylinder flange 36 with head 34 of element 32, t9 produce positive valve displacement in the closing direction.

It is to be here noted that the governor 26 includes speed-setting mechanism (not shown) of well known chap acter in load responsive governors of this type, by which the governor maybe set for effective operation under different..load-speed conditions of the engine. In the present example, such setting mechanism is under adjustment control by the, usual manual enginespecd control (not shown) through suitable linkage as indicated at 38. In the non-operating or shut-down condition of the engine, the governor 26 then in inactive condition, locates the valve lever 28 at position A shown in dotted lines, closing the throttle valve 23. The dotted line position B of lever 28,,wherein valve 23 is full open, is effected by the governor responding either to full load torque output of the engine at rated full speed, or to overload torque output within the capacity of the engine. Now when the engine is started (in suitable manner) for operation initially at its normalno-load, idling speed, the governor 26 (as it may be adjusted through linkage 38 to a low or idle speed setting) functions during starting and engine acceleration to idling speed, toopen the throttle valve for gaseous fuel admission to the engine. Under normal conditions, governor operation of the valve at such time, effe c ts valve opening to an open condition represented by governor location of the valve lever 28 at say position C which in the present example, may represent the extent of valve opening required for throttling fuel delivery to a pressure and rate of feed sufficient for effecting engine acceleration to idling speed. The solid line position D of the valve lever is that in which the throttle valve is in its optimum open position establishing gaseous fuel delivery to the engine at a rate of feed and pressure just sufiicient for maintaining no-load, idling speed operation of the engine. The latter position normally is effected by the governor 26 as the engine reaches and assumes its noload idling speed. While the foregoing is the normal function in bringing the engine to no-load, idling speed operation, under certain conditions including adjustment of the governor to its high speed setting at starting, the governor may tend to and actually open the throttle valve to an excessive open condition. The resultant over-rich fuel mixtures in this event, would be productive of no better than sporadic engine firing and more usually, engine stalling as before indicated.

The latter character of governor-valve operation usually obtains in even more pronounced degree, consequent to loading of the engine. For example and as discussed at the outset, upon applying a load to the engine the operator usually adjusts the governor from its low speed setting (under no-load, idling operation of the engine) to its high speed setting, whether or not the load applied is low, intermediate or a maximum. The governor then in response to the load on the engine, actuates the throttle valve in the opening direction and tends to move the valve to its 'full open position, admitting fuel to the engine in excessive amount. The result is an over-fueling of the engine with consequences as before mentioned. This condition at times, may be such as to choke the engine to the point of engine stalling, before the engine can accelerate to a speed providing the requisite engine torque output equal to the applied load, at which point the governor normally would have returned the valve to its optimum open position for maintaining such engine speed under the applied load.

, Therefore, the present invention contemplates additional control means to assure proper fuel regulation under the hereinbefore indicated critical engine operating conditions. Such control now to be described, is of a character acting in direct accordance with engine speed, to restrict or limit valve-opening displacements of therthrottle valve by the governor, and to assureultimate governordisposition of the valve in its optimum positions, determining engine fuel delivery in proper quantity and pressure feed 4- required under each condition in the range of engine operation. As shown, there is provided a pressure responsive device 40 which is operatively subject to the air pressure in the engine air supply manifold 14 wherein as before indicated, the air pressure varies directly with engine speed. Device 40, which may be of any suitable type, preferably comprises a cylinder 41 having its head end 42 in communication with the engine air manifold 14 through an air line 44, a piston 45 slidable in the cylinder and spring-loaded in the direction of cylinder head 42 by a compression spring 46, and a control element 48 carried by piston 45 and projecting from the cylinder. Element 43 has a laterally extending terminal end 49 arranged relative to the end 50 of throttle valve lever 28, as shown, to provide a lever stop. While the terminal end 49 may afford the lever stop through direct contact thereof by the valve lever end 5%, it is preferred to provide an adjustable stop element in the form of the screw 52 threaded to end 49 to afford the lever contact part of the stop. 7

The device 40 is so selected as to its operating characteristics, and so operatively related to the valve lever 28, that as the engine accelerates to its no-load, idling speed, the stop 52 following such acceleration, retards governor operation of the throttle valve and hence prevents an over-opening of the throttle. I When no-load, idling speed is attained, the stop 52 will occupy the position shown in solid lines in the drawing, while the governor 26 will have moved the throttle valve in its closing direction, to its optimum open position (position D of the lever arm) establishing gas feed to the engine in quantity and pressure sufficient to maintain engine operation at its no-load, idling speed. In position D of the valve lever 28, the lever end 50 is clear of the stop 52, as shown. The spacing of the stop and lever end is here selected and adjusted through screw 52, to allow limited governor opening actuation of the throttle valve under subsequent engine requirement of more fuel, as upon loading of the engine, whereby to effect initial engine acceleration under the load condition. When load is applied, the governor increases the open condition of the valve, to the point of engagement of the lever end 50 with the stop 52. Then, as the engine accelerates to a speed affording the necessary engine torque output equal to or commensurate with the applied load, the speed responsive stop device operates to move the stop 52 upwardly, thereby correspondingly permitting governor opening movement of the throttle valve at a rate corresponding to engine acceleration produced upward displacement of the stop. When the required speed is reached, the governor then reduces the open condition of the valve to its optimum position for the new speed and load condition of the engine, wherein the valve lever end 50' is again spaced from the stop 52. This same function obtains in conditioning of the engine for all loads within its operating range. Very importantly, moreover, it is to be noted that the engine speed limitation upon governor actuation of the throttle valve is such as to render the fuel control system fool-proof, so that the operator may effect high speed adjustment of the governor in any load application, without causing the engine stalling condition asindicated.

It is to be observed that thestop acts only to limit opening movements of the throttle valve by the governor, and that upon any contact of the lever 28 with the stop 52, the governor may continue movement of the cylinder elc ment 31 in the direction tending to effect further opening of the throttle valve, in which case the spring 35 will yield to permit such movement of the cylinder element. The engine speed responsive device 40 providing the limiting stop 52, thus cooperates with governor actuation of the throttle valve in effecting regulation of gaseous fuel admission to the engine under the conditions stated, to establish such'pressure'and quantity of fuel delivery as will avoid difficult or impossible to ignite rich mixtures and consequent engine this-firing and stalling.

It is to be noted here that the speed responsive stop device as herein provided for the purpose described, is effective as an engine overload control under any speed and load operating condition of the engine. For ex: ample, assume that the engine is in normal operation at say three-quarter speed under full or one-hundred percent load for such speed. Now, if the engine is subjected to a sudden or rapidly applied over-load beyond the engine capacity at such speed, as for example a onehundred and forty percent load, the governor will respond to attempt throttle valve opening for increased fuel admission. However, governor opening of the valve will be halted by the stop 52. Thereupon and unless the overload is promptly removed, the engine speed will decrease, with resultant lowering of the stop 52 and consequent stop movement of the valve arm 28 in the direction of throttle valve closure. Consequently, with insufficient and in fact decreasing fuel admission, the engine will stall or cease operation. This additional function of the speed responsive stop device is such, then, as will preclude engine operation in any overloaded condition.

While in the diagrammatic, exemplary embodiment of the engine fuel control system as shown, the pressure operates, engine speed responsive device it) is actuated by air pressure from the engine air supply manifold 14, it is to be understood that the device 40 may be provided or adapted for response to any other fluid system embodied in the engine and in which the pressure or temperature of the fluid therein varies in direct accordance with engine speed. For example, such other fluid system may be the jacket cooling water system of the engine (not shown) in which the temperature of the cooling water or other coolant fluid is proportional to engine speed, or it may be the pressure lubricating oil system of the engine (also not shown).

In accordance with the improved method and manner of engine fuel delivery control as herein provided, it will appear now that the fuel supplied to the engine is controlled in respect to pressure and quantity delivery thereof, by regulation of the fuel supply in direct accordance with engine torque output or loading under a limiting control according to engine speed. It is found that this method and arrangement of fuel control is highly effective for the purpose described.

Having now described and illustrated the present invention, what it is desired to claim and secure by Letters Patent is:

1. In an internal combustion engine operable on gaseous fuel, means for supplying gaseous fuel under pressure to the engine, said means including a gas throttle valve, engine operated means responsive to engine loading, connected to said valve for actuation thereof in accordance with engine loading, and control means independent of said engine operative means, operatively associated with the engine and responsive to variations in engine speed, said control means being effective upon said throttle valve for restricting variably in accordance with engine speed, valve actuation by said engine operated means.

2. In an internal combustion engine operable on gaseous fuel, means for supplying gaseous fuel under pressure to the engine, said means including a gas throttle valve having a valve actuating member, engine operated means responsive to engine loading, connected to said valve actuating member for valve actuation thereby to and between valve closed and valve open position in accordance with engine loading, and means operatively associated with the engine and responsive to variations in engine speed, providing a control element effective directly upon said valve actuating member to limit in accordance with engine speed, the range of movement of said member by said engine operated means.

3. In an internal combustion engine operable on gaseous fuel, having a fluid pressure system in which the pressure of the fluid therein is directly proportional to engine speed, a supply system for the delivery of gaseous fuel under pressure to the engine, said supply system including a gas throttle valve, a valve operating element, an engine 8 driven governor in connection to said operating element for operating said throttle valve, and means operable in accordance with pressure v .tions in said fluid pressure system, for correspondingly r .tricting governor operation of said valve operating element.

4. In an internal combustion engine operable on gaseous fuel, having a fluid pressure system in which the pressure of the fluid therein is directly proportional to engine speed, a. supply system for the delivery of gaseous fuel under pressure to the engine, said supply system including a gas throttie valve movable to and between valve open and valve closed positions, an engine driven governor in operating connection to said throttle valve, and means operable in accordance with pressure variations in said fluid pressure system, for correspondingly restricting governor operation of said throttle valve in the direction of its valve open position.

5. In an internal combustion engine operable on gaseous fuel, having a fluid pressure system in which the pressure of the fluid therein is directly proportional to engine speed, a supply system for the delivery of gaseous fuel under pressure to the engine, said supply system including a gas throttle valve movable to and between valve open and valve closed positions, a valve operating element movable with said valve, an engine driven governor in connection to said operating element for operating said valve, and means responsive to pressure variations in said fluid pressure system, providing a stop in the path of movement of said valve operating element and positionable therein in accordance with the fluid pressure in said fluid pressure system, to limit movement of the operating element by the governor in the direction to move said valve toward valve open position.

6. In an internal combustion engine operable on gaseous fuel, having a fluid pressure system in which the pressure of the fluid therein is directly proportional to engine speed, a supply system for the delivery of gaseous fuel under pressure to the engine, said supply system including a gas throttle valve movable to and between valve open and valve closed positions, a valve operating element movable with the valve, an engine driven governor, a yieldable operating connection between said governor and said operating element for governor operation of said valve, and means responsive to pressure variations in said fluid pressure system, providing a stop in the path of movement of said valve operating element and positionable therein in accordance with the fluid pressure in said fluid pressure system, to limit movement of the operating element by the governor-in the direction to move said valve toward valve open position, said yieldable operating connection in movement limiting engagement of said operating element with said stop, yielding to permit governor operation tending to cause valve operation toward open position.

7. The method of controlling gaseous fuel supply to an internal combustion engine, comprising regulating the volume and pressure of gaseous fuel delivery to the engine in accordance with engine loading, and, during normal engine operation, variably restricting said regulation in the fuel volume and pressure increasing direction only, in accordance with engine speed.

8. A method of controlling gaseous fuel supply to an internal combustion engine having fuel delivery means including a throttle valve, comprising operating the throttle valve between closed and open positions responsively to and in accordance with engine loading, and, during norm-a1 engine operation, restricting the extent of valve operation in the opening direction only, in accordance with engine acceleration consequent to load application to the engine, to a speed commensurate with the applied load.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,452 Hobart Aug. 31, 1943 2,529,437 Weinberger Nov. 7, 1950 2,722,926 Bradnick Nov. 8, 1955 2,727,501 Worth Dec. 20, 1955

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