US2152287A - Automatic safety device for internal combustion engines - Google Patents

Description

L L. SCOTT 2,152,237 AUTOMATIC SAFETY DEVICE FOR INTERNAL COMBUSTION ENGINES March 28, 1939.

Filed April 8, 1 937 INVENTOR Le/ 0a A. 5602)? BY ATTORNEY Patented Mar. 28, 1939 UNITED F F1 GE AUTOMATIC SAFETY DEVICE FORINTERNAL COMBUSTION ENGINES V Leland L. Scott, Kansas'City. Mo. "Application-April -s, 1937,:SerialNo. 135,722

5 Claims.

Inaccomplishing these and other objects of the invention, I have provided improved details of structure, thepreferred' form er -Whichis illustrated in the: accompanying drawing, wherein:

Fig. 1 sis: a perspective 7 view of a magneto equipped :with: a safety ::-device: constructed in accordance" with my invention.

Fig.2 is. alongitudinal vertical section through the magneto. and safetydevice.

Fig; 3 is -.a cross. sectiomthrough the :safety .de'yiceon the line; 3'3,:'F.'ig;i2.

:-Fig. :4. is. a' crosstsection'uthroughiv the safety ydeviceon the1linei4--4'; Fig.2.

Fig.6 is av detail fragmentary viewof a modified contact arrangement.

Referring more in. detailutothezdrawing: l designatesa portion ofan internal combustion engine equipped with a conventional :type v.magneto: 2 for: supplying-an ignition current by which the fuel in, the cylinders is ignited.

.Themagneto includes acasingt-3 for housing .the armature 4 and a distributor mechanism 5 which times the points of ignition "in the re- :spective cylinders. The armature 4 is mounted on; spindles. Land 8 'rotatably mounted in. bearingsa 9 .and .l I]. carried by .the casing. Thespin ..d1e '1. carries..a .gear. I meshing. with a suitable .drive gear ,on .the crankshaft of the engine to rotate the armature at a definite speed.- relative .to. that of the engine. .Theudistributing mechanism is operated by a shaft l2 .extendin-gin parallel relation to the axis of the armature and has its ends rotatably mounted in antiefriction bearings l3 and 14. The shaft I2 is driven in timed relation with the armatureby a gear l5 thereon meshing with a gear 16 on the spindle 8, so that it also is driven at a definite speed relative to the speed of the motor. In order to secure the-gear 15, the end-of the shaft I2 is ordinarily provided -With-a shoulder I1 andis threaded as at l8 to --receivea-suitablenut (not shown.) to clamp the gear thereagainstinyassuring' positive operation :Of thesdistributing: mechanism. -The1magnetoiis alsoequipped with a circuit interrupterrlll that K is grounded as at 20 to provide an intermittent current to the spark plugs of the engine.

The magnetothus described. is of a common type such=as used1 onairplane motors and-like 5 engines and specifically forms no part of the present invention other thanaffording .a convenient-mounting for-myimproved safety device,

- now to be described.

As above. mentioned it is the purpose of the 10 safety device toautomatically'disrupt functioning of the ignition circuit when the engine has attained an excessive RIP. M. and is in'danger of running away caused by sudden release of the engine from its working load. For example,

when an airplane is infli'ghtg the engine isoften released fromits Working load due to loss of the propeller" from breakageor other causes, consequently-upon relief of itslload the speed of the engine increases ata rapid rate to cause ex- 0 cessive 'vibration. The speed and :vibraticn increase so suddenly"that,-before the pilot becomes aware of the'fa'ct, the-engine has shaken itself loose from its support or has caused serious damage to the plane. notice the sudden racing of the-engine, tit is a physically impossible for him to manually-shut -off the ignition before damage has resulted.

*The present invention forestalls disastrous resultsby automatically; grounding the= magneto current, or in case of the ordinary battery ignition, by automatically opening the battery circuit. This is accomplished in the first instance by tripping a switch to closed position-and in 1 the latter instance by tripping a switch to open position, as now tobe described.

In the illustrated instance the safety mechanism is mounted directly upon the magneto and. includes a bell-shaped housing 2| comprising-a cylindrical base portion 22 and a cap portion 23 which may be formed of insulating material.

The base portion 22 includesa flange portion 24 cooperating with the magneto housing to enclose the gear |5.and issecured in positionby fastening devices '25 extending-through openings" 26 in tithe flange-portion and-iintosthreaded openings 21 in the magneto casing, as shown in Fig. -12. The oppositeend of the-portion 22 terminates'in an inwardly extending .flange 28. forming a 1seat.29 for:an annular flange '30 of the cap portion-23, :which is secured thereto by fastening devices 3|.

Mountedon the endjOf the shaft I2 is a governor carrier member 32 including a cylindrical bcdy' '33; provided-with, an internal: cylindrical .socket? shaving; :threads 31 conforming to'the Even shouldthe pilot 25 threads l8 on the shaft |2 to retain the carrier thereon and to take the place of the nut usually employed to clamp the gear l5 against the shoulder IT. The body of the carrier is slotted at opposite diametrical points, as at 38 and 39, and carries spaced ears 40 and 4| extending radially from opposite side edges of the slots to accommodate governor arms 42 and- 43 therebetween.

The governor arms include bell crank levers having hub portions 44 pivotally mounted on pins 45 having their ends mounted in the cars 48 and 4|. The outer arms 46 of the levers normally extend in parallel relation to the axis of the shaft and carry governor weights 48 while the inner arms 49 extend within the socket 34 to engage the head 50 of a trip pin 5| which is slidably mounted therein and has its shank 52 slidably mounted in the bearing opening 53 provided in the carrier in line with the axis of the shaft 2.

Sleeved over the shank 52 is a spring 54 having one end bearing against the head'50 and its opposite end against the bottom of the socket 34 to normally urge the head against the arms of the bell cranks for retaining the Weights in retractive position when the engine is operating at normal speeds. The tension of the spring is, however, such as to allow the weights to move the pin outwardly in the direction of the cap portion 23 of the housing whenever the engine speed is such as to cause the centrifugal force of the weights to overbalancethe spring. It is thus apparent that whenthe engine begins to race or exceed its rated R. P. M. the weights will cause projection of the trip pin from the end of the governor carrier to trip' a switch mechanism now to be described.

The switch mechanism is carried by the cap section of the housing and includes a fixed contact member 56 comprising a headed pin 51 having its shank 58 extended through an opening 59 in the cap at a point spaced laterally from the extended axis of the governor carrier. The shank 58 isthreaded to receive a nut 60 to draw the contact head against its seat 6| in the housing and to provide a terminal 62 for securing the ground wire 63 of the magneto which leads.

through a switch 64 in the cock-pit of the airplane for manually disrupting the ignition circuit by grounding the current generated by the magneto when it is desired to stop operation of the engine.

' The switch mechanism also includes a contact plunger 65 having free sliding fit in a bearing opening 66 that is formed in the housing in line with the trip pin 5| and includes a cylindrical sleeve portion 61 having a through bore 68 to slidably mount a control pin 69 and to house a spring 10.

The control pin 69 is backed by the spring 10.

which has its opposite end engaging the end H of an adjusting screw 12. The adjusting screw is threadedly mounted in the end of the bore farthest from the pin 5| and carries a lock nut 73 to engage the end of the contact plunger for locking the screw in adjusted position, as later described.

The outer end of the pin is retained by the spring 10 against an arm 14 of a bell crank latch lever 15 that is pivotallymounted on a pin 16 extending transversely of the housing below the plunger at a point between the governor carrier and the contact plunger, as shown in Fig. 2. The other arm 11 of the bell crank lever terminates in a hook 18 to engage a latch head 19 on the plunger, the latch head being cone-shaped to provide an inclined surface to guide the hook into latching engagement with an annular shoulder 8| formed by the head. Also provided on the plunger is an annularly extending contact plate 82 arranged to engage the fixed contact member 56 but which is normally retained out of engagement therewith by the latch lever.

It is, therefore, obvious that the hook on the latch lever is engaged with the shoulder 8|, the arm 74 thereof being engaged by the control pin and the spring 10 is retained thereby under tension to keep the latch engaged for holding the contact plate out of contact with the fixed contact member 56.

In order to set the latch I provide a lever 83 pivotally mounted in a slot 84 in the casing on a pin 85 and which has one end 86 projecting in the path of the contact plate and its opposite end 81 secured to a flexible cable 88 leading to the cock-pit of the airplane.

In using the device constructed andassembled as described, the spring I0 is adjusted to the proper tension by manipulating the adjusting screw 12 to resist action of the trip pin 5| until 4 the R. P. M. of the engine approaches the danger point. The contact plunger 65 is then moved into latching engagement with the latch lever 15 by pulling on the cable 88. This causes the end 86 of the lever 83 to engage the contact plate 82 for moving the plunger 65 until the hook l8 rides over the head 19 and engages the shoulder 8|. The latch then retains the switch mechanism in set condition ready to be tripped by the trip pin 5| should the engine exceed a predetermined speed as set by the adjusting screw 12.

Under ordinary engine speeds, the pressure of themain spring 54 is enough to keep the trip pin from contact with the latch lever and the governor weights in retracted position. It is thus apparent that under ordinary engine speeds, there are no moving parts subject to wear or to get out of adjustment but should the R. P. M. of the engine approach the danger point, the centrifugal force caused by the increased rotational speed of the shaft 2 will cause the governor weights to move outwardly. This causes the governor arms to move the trip pin 5| against tension of the spring 54 until the end thereof engages the arm 14 of the latch lever. When the centrifugal force increases to overcome the resistance of the spring 10 the latch lever is rocked to cause release of the latch hook 18, whereupon the spring 16 expands and acts against the end of the adjusting screw to move the plunger outwardly in its bearing and the contact plate 82 into engagement with the fixed contact 56. This grounds the magneto current through the plungor 65 and housing 2| to stop operation of the engine in the same way as the manually operated switch 64.

The pilot may re-establish the ignition circuit by pulling upon the cable 88 but if the cause of the excessive engine speed has not been repaired,

the safety device will. again function to stop is obvious that the ignition circuit will be broken when the safety device functions; otherwise the construction will be identical to that shown in Figs. 1 to 4.

While I have particularly described the safety device as being mounted on the magneto, it is obvious that it may be mounted uponany convenient rotating shaft of the engine without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. An ignition omitting mechanism for internal combustion engines including a housing, a fixed contact carried by the housing and adapted to be connected with an ignition circuit of an engine, a contact member movable in the housing to and from contacting relation with the fixed contact, a bell crank latch lever pivotally mounted in the housing and selectively engaging the contact member, trip mechanism in the housing engageable with an arm of said bell crank lever, a spring normally retaining said bell crank latch lever in latching engagement with the contact member and for urging said contact member into one position relatively to the fixed contact, and means responsive to speed of the engine for actuating the trip mechanism.

2. An ignition omitting mechanism for internal combustion engines including a housing, a fixed contact carried by the housing and adapted to be connected with an ignition circuit of an engine, a contact plunger slidably mounted in the housing and movable to and from contacting relation with the fixed contact, a control pin slidable in the contact plunger, a bell crank lever pivoted in the housing and having a latch-shaped head engageable with the contact plunger and having an arm engaged by said control pin, a spring normally urging the control pin into engagement with said bell crank arm to maintain said latching engagement with the contact plunger and t yieldingly urge said contact plunger into one position relatively to the fixed contact upon release of-said latching engagement, trip mechanism in the housing for releasing the bell crank lever, means responsive to speed for actuating the trip mechanism, and means carried by the housing for relatching the bell crank lever with said contact plunger.

3. An ignition omitting mechanism for internal combustion engines including a housing, a fixed contact carried by the housing and adapted to be connected with an ignition circuit of an engine, a contact plunger slidably mounted in the housing and movable to and from contacting relation with the fixed contact to control the efiectiveness of the ignition circuit, a control pin slidable in the contact plunger, a spring in the plunger engaging the control pin, means threaded in the contact plunger for tensioning the spring, a latch lever adapted to engage the contact plunger and .having an arm engaging the control pin to tension said spring, means for pivotally mounting the latch lever in the housing, a trip mechanism in the housing adapted to engage the latch lever to release the contact plunger, and a governor adapted to be actuated by speed of the engine for operating said trip mechanism.

4. An ignition omitting mechanism for internal combustion engines including a housing, a fixed contact carried by the housing and adapted to be connected with an ignition circuit of an engine, a contact plunger slidably mounted in the housing and movable to and from contacting relation with the fixed contact to control the effectiveness of the ignition circuit, a control pin slidable in the contact plunger, a spring in the plunger engaging the control pin, means threaded in the contact plunger for tensioning the spring, a latch lever adapted to engage the contact plunger and having an arm engaging the control pin to tension said spring, means for pivotally mounting the latch lever in the housing, a carrier member rotatably mounted within the housing, governor weights pivotally mounted on the carrier member, means adapted to be actuated by the engine for rotating the carrier member, and a spring tensioned trip member slidable in the carrier member for normally retaining the governor weights in retracted position but movable in response to movement of the governor weights to trip said latch lever to release the contact plunger.

5. An ignition omitting mechanism for internal combustion engines including a housing, a fixed contact carried by the housing and adapted to be connected with an ignition circuit of an engine, a contact plunger slidably mounted in the housing and movable to and from contacting relation with the fixed contact to control the effectiveness of the ignition circuit, a control pin slidable in the contact plunger, a spring in the plunger engaging the control pin, means threaded in the contact plunger for tensioning the spring, a latch lever adapted to engage the contact plunger and having an arm engaging the control pin to tension said spring, means for pivotally mounting the latch lever in the housing, a carrier member rotatably mounted within the housing, governor weights pivotally mounted on the carrier member, means adapted to be actuated by the engine for rotating the carrier member, a spring tensioned trip member slidable in the carrier member for normally retaining the governor weights in retracted position but movable in response to movement of the governor weights to trip said latch lever to release the contact plunger, and manual means carried by the housing for resetting the latch lever.

LELAND L. SCOTT.

Images