US2799783A - Internal combustion engine idling device - Google Patents

Description

July 16,1957 w. E; MGFARLAND 2,799,783

' INTERNAL COMBUSTION ENGINE IDLING DEVICE Filed sept. 2. 1954 4 sheets-sheet 1 July 16, 1957 w. E. MGFARLAND 2,799,783

INTERNAL COMBUSTION ENGINE IDLING DEVICE Filed sept. 2. 1954 V4 sheets-sheet 2 /40 56 yf/ J5 Q4 Lg @M/, l

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July 16, 1957 w. E. MCFARLAND 2,799,783

INTERNAL coMusTroN ENGINE IDEING DEVICE Filed Sept. 2, 1954 l 4 Sheets-Sheet 3 Y f 4f f6 40 J7 gmyi `July 16, 1957 W. E. MGFARLAND 2,799,783

INTERNAL coNBUsTroN ENGINE IDLING DEvIcE Filed sept. 2, i954 4 sheets-sheet 4 IN V EN TOR.

BY @i NEE/W,

United INTERNAL COMBUSTION ENGINE IDLWG DEVICE This invention relates to a device for controlling the speed of internal combustion engines. Specifically, it deals with an idling device for obtaining lowered speed when there is no load demand, said device utilizing electromagnetic means energized by generated current for directly controlling a throttle connected to the engine governor by a one-way yielding linkage. It further deals with force means connected, at least in part, with the governor and the throttle to provide low speed, non-hunting idling of the engine at no load, without interference of the operation under normal load.

Although the invention is adaptable to any internal combustion engine intermittently subjected to load, it is particularly suited for use with engines driving electric generators. An idling control according to the present invention is one which acts directly on the primary governed throttle, rather than on any special control throttle, the latter being considered impractical in general because of carburetion characteristics.

A practical idling control must respond instantly and directly to initiation and termination of load current flow. Some idling devices of the prior art have employed electromagnetic means of indirect type, mainly because direct throttle motivation was impossible due to deficiency of power to actuate the throttle directly. Use of a hydraulic time-delay feature may be satisfactory for welding applications, for example, but it is unsuitable in applications Such as lighting, operation of machine tools, and the like. The prior art has disclosed use of an electromagnet for actuating an ungoverned throttle, and certain miscellaneous types of idling controls have utilized at least a partial modified connection between the governor and the throttle, but none of them has succeeded in effectively idling an engine at low speed in a simple and effective manner.

The present invention is particularly adapted to small plants for individual applications where load demand is significantly intermittent, yet there is need that the plant be maintained running and warm, between load demand.

Small electric plant engines are controlled by a speed governor which, most frequently, is the conventional centrifugal governor, but which may be an electromagnetic type of governor. In either case, the governors function is to regulate the throttle valve position yso as to maintain operating speed within desirably close limits. Normal engine speed is relatively high in small plants, and it is most desirable that some provision be made to render the governor ineffective for enforcing the operating speed at termination of load current flow, with the throttle held closed sufficiently to limit fuel ilow to a slow idling speed requirement.

Present idling devices are responsive to initiation and termination of current flow in the load circuit to alternately restore the effectiveness of the governor and close the fuel valve (throttle) with the governor ineffective, as the load comes on or off. Such devices require a sensing element, generally an electromagnetic device eners atent ice gized at initiation of load current liow, and which, in turn, controls the operation of a separate motive device such as a hydraulic cylinder which, in turn, alternately applies or relieves Asufficient force on the governed throttle (valve) to obtain the necessary control. It will be understood that where an idling `device is used, that at idling speed there is a collapse of generated voltage which is especially severe if the idling speed is made suitably slow as to allow the engine to run quietly and with very little fuel. The initial action of the sensing device necessarily is based on the initial ow of load current which obviously is relatively low and is particularly so if the initally connected load is a small one. Hence, it is impractical to obtain significant motive force and effect from the sensing electromagnet, making it necessary to employ auxiliary hydraulic pressure as the necessary motive power. Such conventional idling devices have found only limited use, due to their complexity and to the fact that hydraulic pressure is not always available in most of the modern small engines. In order to be widely applicable, the idling control would have to operate entirely from generated current, both with respect to the sensing element and motive power, since generated current is the most readily available motive power in small generating plants.

In its more specific aspects, this invention embodies the following elements: (l) a light force means (such as a spring) acting to pull the throttle open, if unhindered, (2) a one-way yielding linkage (such as a collapsible linkage like a chain) between the governor and the throttle which, in the non-yielding direction, allows the governor to close the throttle, if unopposed, (3) an arm, capable of being electromagnetically actuated, connected with the throttle, (4) a relatively heavy force means (such as a light spring) connected to and exerting a force on Said arm to close the throttle, and (5) electromagnetic means which, when energized, will pull said arm and permit wider opening of the throttle. The invention will be more readily understood by reference to the accompanying. drawings in which Figure l depicts a diagrammatic view of an engine, throttle, engine governor, generator and interconnected idling means in the idling condition, while Figures 2 and 3 depict the same system in various degrees of on-load condition. Figures 5 and 6 are similar views of another modiiication of the present idling device, while Figures 7 and 8 present similar views 0f still another embodiment of the present invention with respect to idling means. Figure 4 is a side view of a modified electromagnet plunger, while Figure 9 illustrates a perspective view of one type of one-way yielding linkage disclosed herein. A system depicting shunt energization of the electromagnet is represented in Figure l0. Similar numerals refer to similar parts in the various figures.

Referring again to the drawings, and particularly to Figure l, numeral 1 represents an internal combustion engine, such as a small gasoline-driven engine which is not shown complete in all details, and which has crankcase 2. Engine 1 is Idirectly connected with a D. C. generator 3 having shunt field 4, or it may be connected to an A. C. generator 3 having separate exciter 5 and field 6, which may be a common field for both excitation and load current. The present invention is applicable to most types of small generators.

For the governor for the engine, there is depicted generally a conventional centrifugal governor l0 having the usual operating lever or arm 11 which, in ordinary practice, is connected directly by rigid linkage with the engine throttle to control the fuel supply. The effect of the centrifugal mechanism, when engine 1 is running, is to drive governor lever 1l to the left as engine speed is increased, while a loading spring 12 (connected to lever 11) serves to pull lever l1 continuously to the right.

Motion of the operating lever11 can occur only when engine speed is within a predetermined relatively close range. Should engine speed exceed this range, the lever 11 will move to the left until adjustable stop 13 is reached, until the excess speed is corrected. Likewise, .if engine speed should fall below the predetermined range, lever 11 will move to the right up to limit pin 14 untilspeed is corrected to within the operating range. Within the pre-determined range, the centrifugal force of thegovernor and the force of loading spring 12 arein approximate balance. Lever 11, however, will be driven lightly to and fr as the speed varies within the Apredetermined limits and, in this condition, lever 11 can be displaced temporarily by very light manual pressure. However, if the engine speed is very low, with the lever -11 at the rightmost limit, the effort required to displace the lever manually will besignicantly noticeable, as the centrifugal force does not now appreciably oppose and balance the force exerted by loading spring 12. An adjusting nut 15 permits changing of the tension of loading spring 12 so that the effective governed speed can be changed within reasonable limits.

Fuel intake pipe connects a carburetor 21 with the engine. A throttle valve 22 (hereinafter designated as the throttle) is disposed within intake 20 by means of pivot pin 60 to which is fastened (outside of intake 20) throttle arm 23. Movement of this throttle arm or lever moves the interiorly disposed throttle 22. In present gasoline engines, the throttle is integrally mounted with the carburetor, but it is shown separately here for sake of clarity. An adjustable stop 24 determines one limit of motion `of throttle arm 23 and thus provides a fixed limit of throttle closure which may be that limit which would provide only suicient fuel to maintain a slow idling speed. Spring 25 is affixed to arm 23 and to the intake at 61 and is of sutcient strength only to move the throttle open, with reasonable rapidity, against incidental friction and inertia.

One important feature of the present invention is the one-way yielding linkage 26 connecting the lower portion 62 of throttle arm 23 with governor arm 11. In this case, the linkage comprises a chain 26 so that throttle valve 22 may be freely closed to its limit independently of the operative position of governor arm 11, as it is desired to close the throttle and hold it closed with the slightest possible motive etort, whereas with conventional rigid connections, closing of the throttle and holding it closed would be resisted significantly by the governor. The particular type of one-way drive used herein depends partly upon the inherent design of the engine, upon the dictates of convenience, and also upon the direction of motion of the governor. In Figure l, the direction of motion of the governor arm is such that it pulls the throttle closed. Thus, a collapsible linkage of the type such as a chain or similar element is most suitable. is apparent from this that if the governor arms motion is such that it must push the throttle closed, then a collapsible member such as a chain cannot be used. In Figure l, the governor cannot resist throttle closure to any degree, yet motion of governor arm 11 for closing the throttle, as necessary, is transmitted positively.

It will be apparent from the foregoing that spring 25 can maintain the throttle only to such advanced limit as is permitted by the position of governor arm 11. Thus,

if spring 25 is unopposed, governor 10 will be normally effective and throttle arm 23 will follow accurately the governing motion of govern-or arm 11. However, if spring 25 is opposed by any additional force, then the governor will be entirely ineffective.

It will be observed further that if spring 25 is unopposed, it is in etfect in parallel with loading spring 12, so that the total eective loading of governor 10 actually is the additive or composite value of the two springs v12 and 25. The action of spring 25 is not a very significant portion of the total, but it is necessary that spring 12 Vbe designed, or adjusted by nut 15, so as to exert a slightly weaker action than in conventional arrangements, so that the total loading will result in an engine speed which would be the same as in a conventional machine.

Another important feature of the present invention is an electromagnetic means, such as electromagnet indicated generally as 30 having steel ends 31 and 31 which are fastened to an angle-shaped bracket 32 at 32', which is conveniently clamped to the engine 1 between fuel intake 29 and the engine proper. Bracket 32 is lof steel, so that ends 31 and 31 together with the bracket ends provide a return path for the magnetic ux.

Electromagnet 30 has a suitable coarse winding 33 disposed in series with load circuit and will therefore be energized for such period as there is load circuit current flow. This winding 33 must be heavy enough to carry the continuous rated load current, and will unavoidably cause at least a small drop in voltage supplied to the load. The available motive energy from theelectromagnet will be quite small at such times as only a small current is owing in the load circuit. A plunger 34 disposed inside coil 33 is connected by link 35 which, in turn, is connected to the top of lever 36. The bottom of lever 36 (which is superimposed over the upper portion of throttle arm 23) is pivoted at pin 60 in swiveling relation thereto. A ange 37 projecting from the right edge of the upper portion lof throttle arm 23 serves as a stop for lever 36, so that further movement to the right (of lever 36) will cause movement to the right of throttle arm 23, resulting in closing of throttle 22.

Spring 38 coiled around plunger 34 exerts pressure against end 31 and stop 63 mounted on the end of plunger 34, thereby exerting a force which pushes plunger 34 to the right to close throttle 22. This spring 38 has just suiciently stronger eliect over that of spring 25 so that plunger 34 is normally held extended with throttle closed (as in Figure l) to the limit determined by stop 24 mounted onintake 20. An iron core or stop 39 is provided in electromagnet 30, so that, upon energization of coil 33 and consequent pulling inwardly of plunger 34 to stop 39, the plunger will lock magnetically in the inward position.

Load circuit 40 carries the current fromgenerator 3 and through electromagnet coil 33 to the variable load 42 which may be appliances of various sizes, the load circuit 40 being adapted to be closed bymeans yof switch 41, which generally is on integral element of the appliance or appliances serving as the load. When switch 41 is open, plunger 34 of electromagnet 30 is extended (as in Fig. l) to close throttle 22 to the limit to supply only minimum fuel which, however, must be suficient to maintain reliable engine operation and prevent complete col lapse of generated voltage. Figure 1 thus depicts the idling position of the system with governor arm `11 at its rightmost position and Vwith sufficient slack in chain 26 so that the throttle could be opened fully, when needed.

When load switch 41 is closed,-the're is an initiation of current in load circuit 40 and electromagnet 30 vwill be at least slightly energized. The initia resistance value of the load (say due to an unstarted motor or a cold lamp lfilament) is much less than the iinal operating resistance, lbut if the load is -too small, there will be insufficient energization of electromagnet 30 to draw in plunger 34. Suiicient energization urges plunger 34 inward, and is aided by spring 25, While stronger spring 38 holds the plunger outward. When energization of coil 33 is sufcient to start the inward motion of plunger 34,'the throttle 22 will begin to open, causing acceleration of engine 1, thus increasing the energization of coil 33, enabling plunger 34 to `morerapidly complete its travel inw-ard (as in Figure 2). Ordinarily,'the plunger will move fully inward before acceleration is complete, and the throttle valve will be fully open, andmost of the slack will be out of chain 26. Governorarm 11 will hold its rightmost position until the nonnal-prcdeterminedrange of speed is reached, but then will move appropriately to a suitable intermediate position and thereafter furnish the necessary govering motion to limit the speed to the proper predetermined rangeY and, with slight tautness in chain 26. Throttle 22 now is being lightly but continuously advanced to the limit imposed by governor 10, which condition will continue so long as plunger 34 is locked in its inward position. k

Upon opening of switch 41, current ow in circuit 40 is terminated and coil 33 will become de-energzed, causing spring 38 to extend plunger 34 into position as in Figure 1, and the throttle again will be held lightly closed. By this means, the governor has desir-ably been made ineective to enforce the load speed during no-load periods, and electromagnet 30 has served as the motive element of direct ycontrol and this, in spite of the fact that the electromagnet is inherently incapableof assuring a significant motive force. The primary functions of idling control have been attained with a structure of maximum simplicity.

As is apparent from Figure 2, which kshows the system of Figure 1 in onload condition, plunger 34 is fully inward, the throttle is Well open, but not full open, indicating medium load. Iron core 39 has been intentionally omitted to illustrate that if the plant is a direct current plant, plunger 34 may be polarized, such as being an Alnico magnet made of an alloy containing aluminum, nickel and cobalt. Such a plunger is more sensitive to move inward upon small current flow, but obviously cannot be allowed to come into close proximity with an iron core 39, as the plunger then would stick in the inward position.

The system depicted in Figure 3 shows a condition when the load is being powered and the throttle is only very moderately open, as would be normal for a light load and the engine would be very prone to fall into the condition known as hunting, a tendency for simple speed governors to oscillate the throttle in a rather rapid pulsing rhythm. Such a condition lcan be partially avoided in conventional electric plants by adjusting stop 24 so that the throttle cannot be closed beyond the strictly necessary extent. However, in the present invention, stop 24 must be so adjusted that the throttle can be almost entirely closed for slow idling. Adjustable stop 13, however, places a limit on the extent to'which the governor can drive the throttle closed. Therefore, it is fully practical to adjust stop 13 so that the governor cannot close the throttle below that extent that will normally provide suiicient fuel for the smallest usual size of load, which provides a greater eiciency in reducing hunting tendency than is possible in conventional plants. It will benoted in Figure 3 that the lower end of governor arm 11 is bearing against stop 13. If the engine is actually hunting, arm 11 will alternately move away from stop 13 and then quickly bump the stop, but the fact that the throttle cannot be excessively closed will soon damp out the hunting tendency.

Figure 3 also illustrates a modied type of plunger 34". In the case of alternating current plants, the voltage drop through winding 33 may be signicantly objectionable due to inductive reactance. This Voltage drop, which is due to increase in reactance as load current flow increases, is greatest when large loads are being handled. When load current flow is large, the ordinary type of plunger tends to become highly saturated magnetically, and the degree of voltage drop will depend in part on the diameter of the plunger and the saturation point of the particular metal. By selecting such a metal as Permalloy (an alloy containing molybdenum, nickel and iron) which saturates at relatively low llux density, the maximum reactance can be reduced. However, particularly to reduce the eiective maximum reactance with ordinary steels, a plunger is provided as shown in Figure 4. It is of markedly reduced diameter 34 for a short length, which may be at or near the end which contacts stop 39. When the electromagnet is only weakly energized, as by initial ovv or powering of a light load, the iiux density will be relatively high in the section 34 which is of small diameter, but there will be no significant loss of sensitivity and motive effect on the part of the electromagnet. When, however, a large load circuit current is flowing, the section 34 having a small diameter will be fully saturated and will have a reluctance comparable with air, so that the effect is equivalent to providing an air gap, which very considerably reduces the maximum reactance of electromag-` net 30.

Figures 5 and 6 illustrate another modification of the one-way yielding connection of the governor with the throttle. In this case, instead of a completely yielding connection in one direction, there is provided a one-way partially-yielding :connection which is applicable where the direction of the governor motion is such that the governor can pull the throttle closed. The chain 26 of Figure l is replaced by a wire link 64, one end of which is pivoted on governor arm 11 at 65 by passing through a hole in the upper portion of arm 11, while the right hand end of link 64 is passed through a ange 66 protruding from the left side of the lower portion of throttle arm 23, through an opening in which link 64 may slide freely. Link 64 has an upturned end 67 which limits the sliding motion. Link 64 acts simil-arly to chain 26 in Figure 1. However, it is possible to coil compression spring 68 around link 64, thereby eliminating spring 25 of Figure l. In this case, spring 68 serves practically the same purpose as spring 25.

Figure 5 shows the system of Figure 6 in idling position. Plunger 34 is extended to press throttle arm 23 against stop 24 and also compresses spring 68 (a very light spring), with governor arm 11 holding its rightmost position because speed is well below the predetermined range. Accordingly, throttle 22 has been freely closed by compression of light spring 68. When 'a suflcient load is connected into circuit 4t?, plunger 34 begins its inward motion. Simultaneously, spring 68 expands and opens throttle 22 and assists in driving plunger 34 fully inward where it becomesrmagnetically locked. Figure 6 depicts the operating positions at the time the inward travel of plunger 34 has been completed. Spring 68 is unopposed and opens throttle 22 to the limit, with flange 66 of throttle arm 23 bearing against the upturned end 67 of metal link 64.

At this instant, however, engine acceleration may not have been completed, and governor arm 11 is therefore shown as still being in its rightmost position. At such time as the predetermined range of load speed is reached, arm 11 will move to such leftward position as is necessary for limiting the engine speed. Figure 6 depicts the system in on-load condition. The load and other elements of the system not shown are the same as those shown in Figure l.

Although spring 68 opens the throttle in the same manner as spring 25 in Figure l, there is a slight diiference in operation once predetermined speed is reached, and governor arm 11 moves leftward. Spring 68, for the duration of speed within the predetermined range, maintains itself fully extended and, whenever governor arm 11 moves rightward, the governors motion is transmitted to the throttle through the spring directly, whereas in Figure l, the governors rightward motion is transmitted by spring 25 indirectly. Whereas spring 25 (Figure 1) is in parallel with the main governor loading spring 12 for the period of load speed operation, the spring 63 is not, and the loading of the governor consists only of spring 12, and no-t the additive value of two springs as in Figure 1. It is therefore not necessary to consider spring 68 when designing or adjusting main loading spring 12. Aside from this fact however, the operating results are the same whether spring 68 is incorporated in link 64 or whether spring 25 (Fig. 1) is so connected that it acts on the throttle independently of the linkage between governor and throttle. A

Another moditication of the present invention is shown in Figure 7. The arrangement depicted therein is aimed to provide a more sensitive degree of control and to show typical connections between governor, throttle and electromagnetic motive element where the design of the engine is such that the operating lever of the governor moves toward the throttle to close it, rather than moving in a pulling direction. Engine 1, crankcase 2, generator 3, tield 4, etc. are the same as those shown in Figure 1. The governor also is of the same general type and has a governor arm 11, loading spring 12, adjustable stop 13, fixed stop 14, and loading spring adjustment 15. However, the general design of the internal centrifugal mechanism of governor 1() is such that the motion of governor arm 11 is reversed as compared with that in Figure 1. Thus, in Figure 7, if engine speed should exceed the predetermined range, governor arm 11 will move to its rightmost limit as determined by stop 13. Likewise, if engine speed should fall below the predetermined range, arm 11 will move to its leftmost limit as determined by the internal mechanism or stop 14 in any event.

Fuel intake 20, carburetor 21 and throttle 22 are as in Figure l. A throttle arm 23 is aixed to throttle 22 and the limit of throttle closure is determined by adjustable stop 24. Spring 25 is aixed to the throttle and urges the throttle to open lightly and will advance the throttle if unopposed. A link 27 of sufficiently rigid tempered wire has one end connecting with throttle arm 23 and a free end extending through a supporting bracket 28. A loop 168 is formed in link 27 surrounding governor arm 11 and providing a thrust means whereby arm 11 can act to close throttle 22. The size and position of formed loop 16S with respect to arm 11 is such that arm 11 can act to close throttle 22 to the extent of the maximum rightward motion of arm 11, and also, when arm 11 is at its leftmost position, it cannot force the throttle open at all. Thus, loop 168 becomes an element of a one-way yielding linkage, resembling chain 26 in Figure l. However, in this case the linkage is employed to push the throttle closed, which would not be possible with a chain.

An electromagnet 50 having end plates 31 and 31 is mounted on a steel bracket 32 and has a suitably coarse winding 51 which may be the inner winding shown. In addition, there may be an additional coarse winding 52 which may be the outer winding and may be slightly less coarse than winding 51. Plunger 53 of the electromagnet has an enlarged flat head 79 against which spring 38 exerts a thrust, so that normally, plunger 53 is extended as shown in Figure 8, when electromagnet 50 is not energized. Extended plunger 53 presses the free end 71 of Vwire link 27 and thus holds throttle arm 23 to the right with throttle 22 closed to the limit for slow speed idling, spring 38 being just suiciently stronger than spring 25 to assure throttle closure.

A current relay 55 having a coarse wound operating coil 56 and contacts 57 and 57 is placed in the circuit as indicated. Relay 55 is of the normally open type and will close its contacts when sutiicient current flows through coil 56. Since the relay is not required to be sensitive to small current flow, it has only relatively few turns and there is no significant voltage drop when current passes through coil 56. The load circuit is represented by numeral 40, and the variable load is indicated by 42.

When load switch 41 is open, there is no load circuit flow initial iiow in the load circuit which will pass through e generator 3, through coarse relay coil 56 (the small initial lHow, however, would not be suticient to pull down the relay armature, so that contacts 57 and 57 will be open rather than closed as shown in Figure 7), thence through .the coarse inner winding 51 of electromagnet 50, thence f' through the less coarse outer winding 52 of the electromagnet, and thence continuing through load circuit 40, switch 41, load 42 and finally through the remaining portion of circuit to the opposite side of generator 3.

Electromagnet thus is suitably energized to draw in its plunger 53 Vso that throttle 22 will be lightly advanced by spring 25 which will thereafter, for the duration of load circuit tlow, hold the throttle advanced to the limit imposed by governor 10 and, as was the case in Figure l. spring 25 will be in parallel with governor loading spring 12. if the initial load is of small size, as stated, and if no `further load is applied during the interval of load speed operation, there will be no further change in the positions of' the control apparatus. If, however, additional load is applied, making the total connected load equal to say .40% of plant capacity, there will then be suflicient current flowing through coil 56 to pull down the armature of relay and thus close contacts 57 and 57. This provides a by-pass circuit through the relay contacts, so that the load current does not any longer pass through the electromagnets outer winding 52, but must continue to pass .through inner winding 51 and thus the electromagnet `50 remains suitably energized and plunger 53 will still be held fully inward.

In the eventsome of the load is removed, bringing the connected loaddown again to say 20% of rated capacity, there will be insuicient energization of relay 55 to hold its contacts closed, and these contacts will open, which will again route the load current through both windings 51 and 5,12 SO that plunger 53 will more positively hold its inward position. However, if load circuit ilow is further reduced, as by switching off all of the load except a very light one, lthe energization may be insuicient and the plunger-53 will again extend and cause reversion to the idling speed.

It is apparent, therefore, that by the system outlined in Figure 7 the electromagnetic sensing element of the idling control system is provided with more turns of winding thanwould be practical for continuous duty, considering the full rated load current ow. Accordingly there have been provided means for suitably bypassing a portion of the turns on occurrence of a certain size of load current flow, but said turns are re-inserted in series with the load circuit if the size of the load circuit flow becomes sufficiently reduced. By the use of extra turns of winding, the ability of the control device to respond yto smaller initial load current tlow is increased, and likewise, the ability to hold the load-speed status until Ysubstantially the last small load is removed.

Although Figures 7 and 8 depict a direct action by plunger 53 upon end 71 of rigid rod 27, it is possible to connect the free end of plunger 53 with the bottom of a vertical centrally-pivoted lever to the upper end of which is slidably connected end 71 of rod 27, so that the directions of motions are reversed. Through the action of the lever, electromagnet 30 then would pull the throttle closed.

As may be understood from Figure 9, it is possible to insert a variable cross-link 72 which may be moved to the right or left, as desired for the control needed.

It will be noted that the one-way linkage in Figure 5 also acts as a throttle opening means independent of the governor arm, through action of spring 68. Also, the

-term speed governor arm employed therein is used to designate all governor throttle control means. In Figures l and 7, spring 25 can be considered as a part of the electromagnet system in that it aids the retraction of plunger 34 when said plunger is retracted by electromagnet 30.

Also, it is possible to insert a relay whose operating coil is in series with the generator and load so that, when a predetermined load current flows through the relay coil, the relay contacts will connect the electromagnetic means. Since the relays operating coil may be disposed in series with the generator and load (as is depicted in new drawing Figure this means that the electromagnet, in such case, is operated by shunt energizatiou. This is illustrated by Figure 10 showing energization of the motivating electromagnet 30, by connecting its winding 33 in shunt with the generator at initiation of load, through means of the contacts 7 and 37' of a current relay which has its coarse operating winding 83 in series with the load circuit 40 so as to close the contacts when the load current starts to flow. Winding 33 necessarily will be of suflicien'tly fine wire to avoid overheating damage, and will be weakly energized initially when generated voltage is low, as in the case of the previous figures illustrating series energization. Figure 10 shows a condition where throttle arm 23 must be moved counterclockwise to close the throttle, and this motion is accomplished by a linkage between plunger 34 and arm 36 which consists of a centrally pivoted vertical lever 35, a link 35 connecting the plunger and the lever, and a link 35 connecting the lever and arm 36. The operation generally is the same as for the other figures, -the governor arm moving to the right to enforce the closing of the throttle. At the termination of load, relay contacts 87 and 87 necessarily open, with spring 38 effecting closure of the throttle for forced idling condition, to cause the plunger of the electromagnet to be withdrawn and become disconnected from the throttle arm.

This application is a continuation-in-part of application Serial Number 346,732, led on April 3, 1953, by William E. McFarland.

I claim:

l. In an idling device for an internal combustion engine-generator set supplying power to a load circuit, the engine thereof having a governed throttle system including a centrifugal governor having a loading spring of such force as to enable regulation of the throttle for maintaining a predetermined load speed operation under varying load, and including a one-way yielding linkage system of operative connection between the governor and said throttle, constructed and arranged to enable said governor to close the throttle only except for the effect upon the throttle by the hereinafter mentioned force system of throttle control, the improvement comprising a dual force system of throttle control including a mechanical light force means, as compared to the force exertable by said loading spring, acting, when unopposed, to urge said throttle open for regulation by the governor at the predetermined load speed, and including a second and stronger mechanical force means acting upon the throttle, when in effect, to overcome lightly said light force means thereby closing the Ithrottle to enforce an idling speed, and an electromagnet energizable by power from a generator of said engine-generator set, during the period from the initiation to the termination of load demand, said electromagnet being connected to said second force means in a manner whereby, as it becomes energized, it begins overcoming the force of said second force means thereby permitting engine acceleration toward the predetermined load speed and, after acceleration, said electromagnet holds ineffective said second force means thereby enabling governor regulation of the throttle for load speed operation, said electromagnet' becoming de-energized at the termination of load demand whereby said second force means goes into efect.

2. An idling device according to claim 1 in which the electromagnet is constructed and arranged to be energized by connection in series with the load circuit of said engine-generator set.

3. An idling device according to claim 2 in which said electromagnet is a plunger electromagnet, the plunger thereof being connected to said second force means for overcoming said second force means when the electromagnet is energized, said electromagnet having two windings for the energization thereof, said windings being in series with each other and with the load circuit, whereby both windings are effective for pulling in said plunger to overcome said second force means at initiation of load demand, and a switching relay constructed and arranged to remove one winding from said series relationship only after initiation of load demand and to restore said latter winding into series relationship at not later than upon termination of load demand.

4. An idling device according to claim 3, in which the two windings are arranged as a two-section winding, and in which said switching means is an electromagnetic current relay having an operating winding in series with the load circuit and is arranged through actuation of its contacts to disconnect one section of said winding from said series relationship only upon a predetermined large load circuit current flow, and to restore said disconnected section of winding in series with the load circuit upon a predetermined smaller load circuit current ow, whereby at light load condition both said sections of winding remain energized to hold the pulled-in status of said plunger.

5. An idling device according to claim 4, in which the two sections of said winding are concentric and, in which the disconnectable section is the outer section and is made of wire less coarse than that of the inner section.

6. An idling device according to claim 1, including limiting means, in addition to the natural limit of governor motion, for limiting the motion of the centrifugal governor whereby closing of the throttle by the governor is prevented, beyond the degree of opening normally required for engine operation at normal load speed under condition of least load.

7. An idling device according to claim 1 in which said light force means is a spring connected to act on the throttle independently of said one-way yielding linkage system whereby the effective loading of the governor to enable regulation of the throttle for maintaining predetermined load s eed operation comprises the sum effect of both said loading spring and said light force spring when said stronger force means is held ineffective by said electromagnet.

S. An idling device according to claim 1 in which the one-way yielding linkage system comprises a rigid rod swivably attached at one end either to the governor or the throttle and slidably attached at the other end of the governor or the throttle, and thrust means provided at the slidable end for enabling the governor to close the throttle.

References Cited in the file of this patent UNITED STATES PATENTS 1,792,241 Ray Feb. 10, 1931 1,991,074 Blankenbuehler Feb. 12, 1935 2,139,931 Brunkow Dec. 13, 1938 2,203,717 Blankenbuehler June 11, 1940 2,242,072 Holslag May 13, 1941 2,396,176 Hobart Mar. 5, 1946

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