US2836159A - Governor for lawn mower engines - Google Patents

Description

May 27, 1958 R. L. MORDEN 2,836,159

GOVERNOR FOR LAWN MOWER ENGINES Filed March 26 1956 2 Sheets-Sheet 1 r S4 45 4 33 o W INVENTOR F16. 2

Pusss-LL L. MORDEN ATTORNEYS.

y 1958 R. L. MORDEN 2,836,159

GOVERNOR FOR LAWN MOWER mamas Filed March 26, 1956 2 Sheets-Sheet 2 IN V EN TOR. Russ-1. .4 L Moeoazv ATTORNEYS.

United States aren't @fihce GOVERNOR FOR LAWN MDWER ENGHNE Russell L. Morden, Lansing, Mich, assignor to Motor Wheel Corporation, Lansing, Mich, a corporation of Michigan Application March 26, 1956, Serial No. 573,92fi

' 18 Claims. (Cl. 123-1tl3) This invention relates to a governor for the internal combustion engines such as used for propelling lawn mowers.

As with many internal combustion engines, the speed of the small engines used on power lawn mowers and similar implements is proportional to the amount of gas-air fuel mixture fed to the engine through an adjustable throttle valve which can be moved from a closed position to an open position,v as desired, to meet demands for power. In the course of mowing a lawn variations in grass growth cause rapidly varying power demands on the mower engine. However, changing the engine speed to meet these demands by continual manipulation of a throttle valve control by the operator is not feasible.

The usual practice is to provide a throttle control means by which the engine speed can be adjusted to any desired level between predetermined minimum and maximum settings. In addition, a speed governor is provided which will automatically open the throttle when an applied load reduces engine speed below the desired level and close the throttle when release of the load allows engine speed to rise above the desired level.

In one type of governor, a vane in the form of a flat plate of metal is hinged at one edge and positioned adjacent the engine flywheel. The vane is operatively connected to the throttle. When the engine is operating, fins on the rotating flywheel direct air against the vane. If for any reason engine speed increases above the level set by the manual control, the resulting increased air pressure on the vane causes the vane to exert a force on the throttle in a closing direction.

To steady movement of the vane, and to insure reopening of' the throttle valve to meet a demand for more power, means are provided for applying a force to the throttle valve opposite to the force applied by the vane. When the engine is operating these two forces tend to balance each other, holding the engine speed fairly constant at the desired level.

One such means commonly employed is a light cylindrical coiled tension spring connected at its ends between the throttle control means and the throttle valve. This type of spring has been found to have serious drawbacks for this application. First, a spring of the proper strength is fragile and readily subject to damage in assembly or in use. Second, the spring vibrates freely between its ends when the engine is running so that the spring is continually changing in overall length and thus exerts a variable force on the throttle valve. Third, such a spring tends to .overcorrect by alternately stretching and contracting beyond the point of balance so that the engine speed continually fluctuates and does not reach a constant level. This fluctuation of engine speed is known as hunting. It is therefore an object of this invention to provide an improved vane type engine speed governor for an internal combustion engine.

Itis a further object to provide such a governor that is not adversely afiected by engine vibration.

It is a further object to provide a governor that will not overcorrect engine speed. 7

It is a further object to provide a governor which permits an engine of a given size to provide more available horsepower than when the same engine is used with a governor employing a cylindrical coiled tension spring.

It is a further object to provide a novel governor spring for use with a vane type speed governor on an internal combustion engine.

It is a further object of the invention to provide a governor spring possessing load-deflection characteristics that vary with time.

In the drawings:

Fig. 1 is a perspective view of a lawn mower including an engine embodying the invention.

Fig. 2 is a fragmentary part sectional plan view of the engine.

Fig. 3 is a perspective view of the improved governor, the engine being shown in dotted lines.

Fig. 4 is a sectional view taken along the line 4-4 in Fig. 2.

Fig. 5 is a view similar to Fig. 4 showing the parts in a different position.

Fig. 6 is a perspective view of the governor spring.

Fig. 7 is a sectional view taken along the line 7-7 in Fig. 2.

Referring to Fig. 1, a rotary type lawn mower may comprise a housing 10 on which wheels 11 are rotatably mounted for moving the housing along the ground. A handle 12 is pivoted to brackets 13 on the housing 10 for guiding the movement of the lawn mower along the ground. An engine 14 is mounted on the housing and is operatively connected to a rotary blade 15 which rotates about a vertical axis and cuts the grass as the mower is moved along the ground.

As shown in Fig. 2, the engine 14 comprises a cylinder block 16 and a flywheel 17 operatively connected to the crankshaft (not shown). The flywheel is provided with fins 18 which direct air across the block 16 to cool the block. The engine also includes a gas tank 20 and a housing 19 surrounding the cylinder block. A carburetor 21 is mounted on manifold 22 which is, in turn, mounted on the engine. An air cleaner 23 is supported on the carburetor for filtering the air which is supplied to the carburetor and the carburetor is'connected to the gas tank 20 by a fuel line (not shown).

Referring to Fig. 3, the carburetor 21 includes a throttle valve 24 in the form of a butterfly or gate valve which controls the flow of gas-air mixture from the conduit 25 of carburetor 21 through manifold 22 to the engine. When the throttle valve is in position with the plane thereof extending longitudinally of conduit 25, the flow of gas-air mixture is substantially undisturbed. As throt tle valve 24 is rotated bringing the plane thereof into a position transversely of conduit 25, the flow of gas-air mixture is progressively restricted and decreased. Valve 24 is mounted on the vertical shaft 26 rotatably mounted in the carburetor and having the upper end thereof projecting through thetop'of the body of the carburetor. A sector plate 27 is mounted on the upper end of shaft 26 with the plane thereof extending generally horizontally. The sector plate is provided with a multiplicity of holes 28 radially spaced from shaft 26.

As shown in Figs. 2 and 3, a governor vane 29, in the form of a flat piece of metal, is pivoted for rotation about a horizontal axis by means of a bracket 30 fastened to the cylinder block. A pin 31 hinges the vane 29 to bracket 30. A wire link 32 has one end thereof fastened to vane 29 and the other end thereof passing through one of the openings 28 in sector plate 27.

When the engine is running, the fins 18 on flywheel 17 force air against the vane 29 causing it to pivot about the Patented May 27, 1958;

. 33'to a new position.

horizontal axis of pin 31 and exert a forceon the throttlev valve 24 through the link 32'tending to tion is-opp' osed' by a governor spring 33} which 'has' one end 34 thereof connected to one-of-the openings iiiinrt the seminars 27. by a short" wire link'35; F'As jshown in -Fig. 6-, the governor spring 33in the untensioned' corn dition comprises a straight upper end 34, a central looped portion-3 and a straight lower'end 37. The coiled CIfil'ltraliportion 36 consists of a plurality of loops or coils in adjacent relationship. Governor spring 33is loosely supported on a collar 38 mounted on manifold 22,1 A spring guide39fis pivoted .jon' the collar and comprises a pair of spaced ears'40 on either sideof the spring 33 connected to each other by an elongated centralp'ortio'n' 43 which acts as a. stop against which the lower fend 37 of the governor spring 33 bears. I I

As shown in Fig, 7', collar 38' includes a flange 42 adjacent and spaced from'the outer'end' thereof. Athrottle lever 43 in the formof a plate is mounted on the outer e'ndof the collar and the collar is supported on the mani- H told. by a bolt 44 extending through the collar. The lever 43' is mounted for pivotal movement with respect to collar 38 by meansofa washer 45 positioned betweenthe end or collar 33 and bolt 44. The space between the y washer 45 andfiange42 of collar 38 is greater than the thiclinessrof the lever 43. A throttle control, cable 46 has one'end thereof fastened to handle 12 (Fig. l) and the other end thereof is positioned near therengine. 7

As shown in Fig. 3, the sheath 47 of control cable 46 is mounted on the engine by a bracket 48 and control wire 49 of cable 46 extends through sheath 47 and is connected to the lower end of throttle lever 43 at a point radially spaced from the collar 38. Throttle lever 43 is load causes the engine speed .to drop, reducing the air provided with an inwardly turned flange 50 through;which a bolt 51 isthreaded with theend thereof bearing against central portion 41 of the governor spring guide 39. A

lock nut 52 is provided to adjust the relative position of V lever 43 with respect to springrguide 39. 'When'the en:

gine is-operated, the position of throttle lever 43 and governor spring guide 39 are fixed'by the position of wire 490i throttle control cable 46 thereby providing a stop for lower end 37 of the governor springb t, r t g t A shield 53 may be provided above the carburetor to protect the various parts and is connectedto thethousing.

by bolts 54 andito the manifold by abracket 55-(Fig.12).

The maximum throttle setting of. the engine may be! adjusted by operating the engine and pushing the throttle 'lev'er143 toward the manifold until it strikes 'a stop 56 on the manifold ,(Fig. 4). With atachometer on the en gine shafgthe speed is adjusted to the desired level by turning bolt 51 thereby adjusting the position of the spring guide 39 and, in turn, the lower end 37 of governor spring 33. By screwing the bolt inwardly, the tension on gove'r nor spring 33 is increased, causing the throttle to open. When the desired setting is obtained, the bolt 51 is locked in position by tightening the lock nut 52. This adjustment maybe made before the engine is 'mounted on the lawn mower and will not be'aftected' by the mounting operation; The maximumsetting of the throttle is thereby fixed and constant once it is adjusted. A

- When cable wire 49 is pulled from the remote position on the handle, lever 43 is moved away from the stop 56 on the manifold, permitting governor spring guide 39 ,to

move with the lever by the action of the governor spring In this position the action of govspeed drops,

ernor spring 33 in opposition: to'vane 29 is less; and, as- I a-result, vane 29-will move or tend to move throttle valve 2 4 to a position more nearly near the closed position of the valve, -thus, lowering the operating speed of the engine. Thus, by-moving the cable, the operatingspe'ed of the engine is controlled'but' can never exceed the speed to which it'has been set or adjusted, sincethe maximum at the maximum speed for the particular throttle cable 1 setting and'the rotation of the flywheel causes air to be forced against the vane 29; The air forced against the vane tends to cause vane 29 to pivot about its hinge and through wire link 32 exert'a force on the sector plate 27 which thereby tends to move'throttle 24 ina closing di-;

'rection (Figs. 2,4). a V y When the moweris moved through grass, theincreased pressure against vane 29'. Governor spring 33,which tends to oppose the movement of the vane, then overcomes the force exerted on thevane and gradually moves throttle 24 in an opening direction until the force on the vane and the force exerted bythe governorspring are againin balance (Figs. 3, 5'). I v J As themower isrnoved' along the" ground and encomi-i ters areas of grass which are not heavy, the load on the" 7 engine is decreased permitting the enginespfeed to increase and causing the pressure on vane '29 to increase there by exerting a force on throttle 24 in a closing direction',

As the lawn mower is moved into areas of grass which are heavier, the load on the engineis increased and the speed of the engine is decreased, thus reducing the air pressure on thevane and permitting governor spring 33 V to move valve 24 in an opening direction to provide the necessary power.

The construction and arrangement of the spring is such that it jis not adversely affected by the engine vibration, 7 1 t i Although I do not wish to be bound by the theory in- .volved, i believe that the significant results obtained by the; use of this governor are caused by-thefdllowing-ao.

tion.

free end and is not the V friction between the coils of the However, engine vibration soon overcomes this friction, and the entire spring, including the coils,'conies intoopcr.-;- ation.; This action results in a slight time delay in opening the throttle, and this slight time system to come into balance without which-produces hunting. r As the load on the engine increases randthe engine: the forceon. the vane due 'to2"air pressure decreases'and the unsupported end of thegovernor spring moves the throttle in an opening direction. Engine vibration then allows the spring to move on collar 38*,and the entire length of the spring comes into operationmoving the throttle further in an opening direction; The final throttle position is such that-the engine speed is very' nearly that which it wasrbefore the load was increased.- However, since the throttle action did not take :place instantaneously, no overcorrection is made, and there is no tendency for the engine to hunt. a a V 7 It is believed that the friction between the .coils oi the governor spring and collar 38 produces a change of sensitivity with time. Thisv permits the use of a flexible spring so that the governor can be quite sensitive. The increased sensitivity results in less loss of speed due to load change, and, as a result, the engine tends to run at a more constant speed; Also, by'permitting the throttle overcorrection to open completely with only-a slight decrease in speed of the engine, a greater portion of the capacity 'ofthe' engine may be utilized. t

1'. In a governor for an internal cornbustion cngine;

fBefore i The amount of deflection of the torsion type gov? ernor spring for the initial interval of time is from the full amount oi deflection due to spring and thecollar 38. I

delay allows. the

having a throttle valve, and a fan operating in accordance with the speed of engine rotation, a vane mounted for pivotal movement in the path of air circulated by said fan, said vane being operatively connected to said throttle valve whereby when the vane responds to air flow from said fan the said throttle valve is moved in a closing direction, a post, and a torsion spring operatively connected to said throttle valve and opposing the closing action of said vane, said spring having a central portion comprising a plurality of coils wound around said post, one end of said spring being operatively connected to said throttle valve and the other end of said spring being anchored.

2. The combination set forth in claim 1 including means for adjusting the position of said anchored end of said spring.

3. in a governor for an internal combustion engine having a throttle valve, and a fan operating in accordance with the speed of engine rotation, a vane mounted for pivotal movement in the path of air circulated by said fan, said vane being operatively connected to said throttle valve whereby when the vane responds to air flow from said fan the said throttle valve is moved in a closing direction, a post, and a torsion spring operatively connected to said throttle valve and opposing the closing action of said vane, said spring having a central portion comprising a plurality of coils wound around said post, a sector plate connected to said throttle valve, and a link extending between said sector plate and one end of said spring, the other end of said spring being anchored.

4. in a governor for an internal combustion engine having a throttle valve, and a fan operating in accordance with the speed of engine rotation, a vane mounted for pivotal movement in the path of air circulated by said fan, said vane being operatively connected to said throttle valve whereby when the vane responds to air flow from said fan the said throttle valve is moved in a closing direction, a collar, a torsion spring operatively connected to said throttle valve and opposing the closing action of said vane, said spring having a central portion comprising a plurality of coils wound around said collar, the ends of said spring extending radially or" said central portion and'diverging, one end thereof being operativel connected to said valve, and a stop member contacting the other end of said spring.

5. The combination set forth in claim 4 including means for adjusting said stop member against which the other end of said spring rests.

6. The combination set forth in claim 5 including manually operated means connected to said adjustable stop member and extending to a position remote of said engine whereby the position of said stop member may be adjusted.

7. The combination set forth in claim 5 wherein said stop member comprises a pair of spaced ears rotatably mounted on said collar and a central portion connecting said ears, said central portion extending radially and outwardly away from said collar, the end of said spring extending along said central portion.

8. The combination set forth in claim 7 wherein said means for adjusting said stop member comprises a lever mounted for rotation about the axis of said collar, a bolt threaded through said lever in such a position that the end of said bolt contacts the central portion of said stop member.

9. In a governor for an internal combustion engine having an intake passageway for supplying a combustible gaseous mixture to said engine and a throttle valve positioned in said passageway for controlling the flow of combustible mixture to said engine, said valve being mounted for rotation about an axis transverse of said passageway, said engine including a crankshaft and a fan operatively connected to said crankshaft and operating in accordance with the speed or" the engine, a vane mounted for pivotal movement in the flow of air from said fan, means connecting said vane to said throttle valve in such a manner that when the vane responds to air flow from the fan the throttle valve is moved in a closing direction, a torsion spring operatively connected to said throttle valve, opposing the closing action of said vane and biasing the throttle valve to open position, said spring including a central portion having a plurality of coils, the ends of said spring extending radially outwardly from said central portion and diverging with respect to each other, one end of said spring being operatively connected to said throttle valve, and a stop mem-,

her for engaging the other end of said spring and limiting its movement in one direction, said spring being mounted for pivotal movement about the am's of said central coiled portion.

10. In a governor for an internal combustion engine having a carburetor, said carburetor having a conduit communicating with said engine, a throttle valve positioned in said conduit and controlling the flow of combustible mixture to said engine, said throttle Valve being mounted on a shaft extending transversely of said conduit, one end of said shaft projecting through the body of said carburetor, a sector plate mounted on the end of said shaft and having a multiplicity of holes therein radially spaced from the axis of said shaft, said engine including a crankshaft and a flywheel operatively connected to said crankshaft, said flywheel .being so constructed and arranged that upon rotation thereof air is circulated about said engine for cooling said engine, a vane pivotally mounted on said engine in the path of air circulated by said flywheel and adapted to be moved by the air pressure caused by rotation of said flywheel, a link extending between said vane and one of said holes in the sector plate in such a manner that when the engine is operated air pressure on the vane tends to move the vane causing the sector plate to rotate and move the throttle valve in a closing direction, a torsion spring operatively connected to said sector plate and opposing the action of said vane in tending to move said throttle valve in a closing direction, a collar, 'said spring having a central portion comprising a plurality of coils wound around said collar, said spring being rotatable with respect to said collar, the ends of said spring extending radially of said central portion and diverging with respect to each other, a link connecting one end of said spring to one of the holes in said sector plate, and a stop member opposing the movement of the other end of said spring in one direction.

ll. The combination set forth in claim 10 wherein said stop member comprises a member mounted for rotation about the axis of said collar and having a portion thereof spaced radially from the axis of said collar, the end of said spring contacting said radially spaced portion, a lever mounted for rotation with respect to the axis of said collar, a bolt threaded into said lever and having the end thereof contacting said radially spaced portion of said member, and means fixing the position of said lever.

12. The combination set forth in claim ll wherein said means fixing the position of said lever comprises a cable having one end thereof connected to said lever, the other end of said cable extending to a position remote of said engine whereby by moving said cable the position of said lever may be adjusted thereby adjusting the position of said stop member and, in turn, the position of the end of said spring.

13. In a governor for an internal combustion engine having a throttle valve and a governor element movable in opposite directions in response to variations in the speed of the engine, a torsion spring comprising a central coiled portion with the ends of said spring extending outwardly from said central portion, said spring being mounted for pivotal movement about the axis of said central coiled portion, one end of said spring being operatively connected to said governor element, and a 1 7 -stop member, for engaging the other end of said spring .andlimiting its movement in one direction.

14. Ina governor foran internal combustion engine having a throttle valve'and a fan operating in accordance with the speedof engine rotation, a vane mounted for pivotal movement, in the ,path of air circulated by said fan, said qvane being operatively. connected to said throttle valve-whereby when'the vane responds to increased airflow from saidfan the throttlej valve is moved in a said central coiled portion, one end of said spring being operatively connected to said throttle valve, and a stop member for engaging the other end of said spring and limitingits movement in one direction.

.15.:The combination set forth in claimgrl4dincluding a post supporting said central portion of said spring.

16. In a governor for an internal combustion engine having an intake passageway for supplying a combustible gaseous mixture to said engine and a throttle valve positioned in said passageway for controlling the flow of combustible mixture to said engine, said valve being mounted for rotation aboutzanaxis transverse of said passageway, said engine including a crankshaft and a fan operatively'connected to said crankshaft andoperating in accordance with the speed of theengine, a; vane mounted for pivotal movement in the path of air circulated by said fan, means connecting said vane to said throttle valve in such a manner that when the vane re- .sponds to increased airflow from the fan the throttle valve is moved in a closing direction, a torsion spring comprising a central coiled portionwith the ends of said spring extending outwardly from said central coiled portion, said springbeing mounted for pivotal movement about the axis of said central coiled portion, one end of said spring being operatively connected, to said throttle valve, and a stop member for engaging the other end of said spring'and limiting its movement in one direction.

17. In a governor for an internal combustion engine 'having a throttlevalve, and a'fan operating in accord .ancewith the speed of engine rotation, a vane mounted tor pivotal movement in the path of air circulated by said fan, said vane .beingoperatively connected to said throttle va'lve wherebywheri the vane responds to in- V creased airflow trom said fan the throttle valve is moved.

in a closing direction, a torsion spring comprising a cen-. tral-coiled portion with the ends of said spring extending outwardly from saidcentral coiled portion, said spring being mounted for pivotal movement about the axis of said 'centralfcoile'd portion, one end of said sp'ringbeing operatively connected to said throttlevalve, a movable stop: member for engaging the other end of said spring and limiting its movem'ent'in onedirectio n, and-manually operated means connected to said movable stop member and extending to a position remote. of said engine where-' by the operating speed of the engine may be varied during operation'by moving said stop member.

18. In a overnor for an internal combustion en ine having a throttle valve, and a fan operating in 'accord- I ance with the speed of engine rotation, a vane mounted for pivotal movem'ent in the path of aircirculated by said fan, said vane being operatively connected to said throttle valve whereby when'the vane responds to increased air flow from said fan the throttle valve is moved in a closing directionya torsion spring. comprising a central coiled portion with the ends of said spring extending out wardly from said central coiled portion, a lever pivotally mounted on said engine, means for mounting said spring for pivotal movement about the axis of the lever, said 7 central coiledlportion of said spring being axially aligned with the axis of said lev'ergoneehd of said spring being? 7 operatively connected to said throttle valve, the-other end of said spring engaging said lever andllimiting its movement in one direction, and means operatively connected to saidlever for adjusting the position of said stop during the operation of the 7 speed.

References Cited'in the. file of this patent. V UNITED STATES PATENTS 1,822,473

Brandl Sept. 8, 1931 r 1,917,790 Baumann Q July 11, 1933 2,548,334

Armstrong ,Apr. 10, 1951' engineto vary the engine

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