US2941049A - Ignition distributors - Google Patents

Description

June 14, 1960 M. BEGIAN 2,941,049

IGNITION DISTRIBUTORS Filed Dec. 27. 1957 s Sheets-Sheet l INVENTOR. MEHRIN BEG IAN ATTORN EYS June 14, 1960 M. BEGIAN IGNITION DISTRIBUTORS 3 Sheets-Sheet 2 Filed Dec. 27, 1957 FIG. 3-

FIG 4 INVENTOR. MEHREN BEGIAN ATTORNEYS States Patent IGNITION DISTRIBUTORS Mehrin Begian, Detroit, Mich., assignor to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Dec- 27, 1957, Ser. No. 705,693

18 Claims. (Cl. 200-31) The present invention relates to ignition distributors.

At very high speeds, the time available for current flow to the ignition coil is very short and as a result the current cannot reach its maximum value and the output voltage is reduced. It has been proposed, in ignition distributors which must operate at speeds where this reduced output is serious, to provide two sets of contacts, wired in parallel and arranged so that their periods of closure overlap. This method increases the closed or dwell time throughout the entire speed range but has the disadvantage that at low speeds where the ignition coil normally saturates anyway, additional energy is provided which must be dissipated in the form of heat.

It is an object of the present invention to provide a means of increasing the dwell time with an increase in' engine speed without the disadvantages inherent in prior devices.

More specifically, it is an object of the present invention to provide speed responsive means effective to pro duce an increase in the dwell time as well as a timing advance.

It is a feature of the present invention to provide in an ignition distributor, a timing cam carried by a rotating drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, in combination with speed responsive means carried by the shaft and operable to produce independent angular and axial adjustment of the cam relative to the shaft.

It is a further feature of the present invention to provide in structure as described in the foregoing a cam of symmetrical pyramidal shape. It is a further object of the present invention to provide in an ignition distributor, a timing cam carried by a rotating drive shaft for rotation therewith and for limited axial adjustment relative thereto, in combination with speed responsive means carried by the shaft and operates to produce axial adjustment of the cam relative to the shaft.

Still more specifically, it is a feature of the present invention to provide a rotary drive shaft, a cross shaft carried by said drive shaft, centrifugal members movable radially on saidcross shaft in accordance with drive shaft speed, a timing cam on said drive shaft adapted to rotate therewith and to have limited angular and axial adjustment relative thereto, and independent means carried by said members and operatively associated with said cam for effecting independent angular and axial adjustment of said cam relative to said drive shaft upon radial movement of said members.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings,

illustrating preferred embodiments of the invention,

wherein:

Figure 1 is an elevation view of the ignition distribu tor, partly in section and with parts omitted. Figure 2 is a diagrammatic plan view of the ignition distributor with the cover removed.

ice

Figure 3 is a fragmentary perspective view of part of the distributor.

Figure 4 is a perspective exploded view of a cam plate and actuator therefor.

Figure 5 is a fragmentary view taken substantially on the line 5-5, Figure 4.

Figure 6 is a section on the line 66, Figure 4.

Figure 7 is an elevational view of a modified form of distributor partly in section and with parts omitted.

Figure 8 is a fragmentary sectional view showing connection of the cam to the shaft.

Figure 9 is a perspective view of a cam form suitable for use in the construction of Figure 7.

Figure 10 is an exploded perspective view of details of the cam actuating mechanism.

Figure 11 is a section on the line 11-11,- Figure l0.

The distributor comprises a housing 10 into which extends a rotary drive shaft 12 adapted to be connected to a rotating part of the internal combustion engine of which the distributor is a part. The distributor includes a breaker plate 14 shown in Figure 2, on which is pivoted a breaker arm 16 the pivot connection therefor being indicated at 18, and serving to mount the breaker arm 16 for rocking movement about an axis spaced from and parallel to the axis of the shaft 12. The ignition circuit includes a stationary contact 20 and a movable contact 22 is carried by the breaker arm 16 for movement into and out of engagement with the stationary contact 2-9. The circuit includes a condenser 24 connected to a terminal 26 from which an electrical conductor 28 leads to the breaker arm 16 through a spring 30, and additional means (not shown) are provided which are effective to bias the breaker arm 16 clockwise as seen in Figure 2. A rubbing block 32 is carried by the breaker arm 16 and is engageable with the cam 34. As is apparent from an inspection of Figure 2, rotation of the cam causesthe breaker arm 16 to move back and forth, making and breaking contact between the contacts 20' and 22.

It will be appreciated that the ignition circuit is adapted to produce sparks within the cylinders of the internal combustion engine in properly timed relation to pis: ton movement therein and as is well understood, it is desirable to. advance the spark upon increase in speed.

In accordance with the present invention means are also provided which are effective to prolong the interval or angular movement of saft 12 during which the contacts 20 and .22 remain in contact upon an increase in speed of the internal combustion engine. This is accomplished by providing the cam 34 in the configuration best illustrated in Figures 1 and 2 and by providing for both limited angular and axial adjustment of the cam rela tive to the shaft 12.

The cam, which is herein illustrated as hexagonal; may of course have a different number of sides depend ing upon the number of cylinders in the internal combustion engine. Inasmuch as separate angular and axial adjustment is provided for the cam and since these ad-' justments may be independently controlled by proper design of the mechanism, it is possible to employ a cam having inclined flat surfaces 36. In other words, the cam is a symmetrical pyramidal body. This is of prac-. tical. importance since this body may be readily produced by' simple and inexpensive methods and apparatus. It is thus possible to avoid the production of contoured cams having three dimensional curves which would other-j wise be required. I

The cam 34 has rigidly connected thereto a cam plate 38 the plate being connected to the cam by a sleeve 40 and the cam, sleeve and plate being freely mounted on the rotary drive shaft 12 for angular and axial movement relative thereto.

Means are provided for driving the cam and cam plate in rotation with the drive shaft and at the same time for effecting limited relative angular and axial adiss m n therwfl This means comprises a cross shaft 42 fixedly carried by. the drive-shaft-,12.. The cross shaft at its ends includes heads 44 constituting abutments for springs 46. Slidably mounted on the-cross shaft 42 for movement radially of the drive shaft 12 are centrifugal weights 48 having flanges 5 engaging the ends or, the springs 46. Accordingly, during rotation of the shaft 12 centrifugal forces developed by rotationof the weights 48 tend to move the weights radially outwardly on the cross shaft 42 and this movement is opposed by the springs 46. Thus, the instantaneous position of the centrifugal weights 43 is determined by thec rrespOnding speed of the drive j I i r I In order to employ radial movement of the weights 48 resulting frornchanges in speed of the shaft 12 to effect independent angular and axial adjustment of the cam 34, each-of the weights 48 is provided with a bracket 52 details of which areibest seen in Figures 3-6.' The bracket 52 comprises. an" elongated portion 54 including an enlarged central eye portion 56 slidable on the cross shaft 42.. At-its opposite, ends it carries forwardly projecting arms 58- and 6d. Thearm 58 is relatively long and adjacent its, outer. end carries a pin 62.

I The plate 38, as best seen in Figure 3, is elongated and adjacent its outer ends is provided with elongated slots 64-for'receiving the pins 62. The plate 38 includes a eentralopening 66 which receives the shaft 12. It will heyobserved. in Figure .3 that the axis of the weight 48 is positioned to intersect the axis of the shaft extending through the opening 66. Accordingly, it will be under.- that the pin and slot connection 62, 64 interconnecting, the arm 58 of the bracket 52 and the, cam plate. 38 isf-located laterally of;, both the shaft 12 and the cross f i i .42, Thus, movement of .the centrifugal weight 48 gathe cross shaft, in. ajdirection radial with respect to the. drive shaft'lz results in angular movement of the plate 38 relative to thedrive shaft 12. The amount of such movement is of course a function of the spacing (gi -the. pin 62 from they axis of the shaft and this may be determinedindependently of the means for effecting axial movementof the camplate. In addition it will be observed that pin. and slot connection 62, 64 serves in all positions of angular adjustment of the cam plate 38 .to transmit the driving, rotation from the shaft 12 hrou h he r ss. s a 42 W h a bracket 52. t2- h .l =em1a ste 8-.; a Th! means for. effecting; axial adjustment of the cain plate '38; comprises a pair of levers 70 pivoted. tov the shaft 12 asin dicat'edifat. 72'. 'The levers 70 are bell Qrank levers. and each. includes: a first. arm 74 slidable 'in elongated slot/7,6 in-the' 'arm 60,'and a second arm 7 78 in engagement with the underside'of the cam" plate 'iifi as best seen in Figure 1. It will be. apparentthat movementofthe weights, 4sj6n'n1ep ss shaft. 42 results in' .r .ocking. movement of the hellcrank levers 70 and'co'rr esponding axial movement of .thecam 34 relative to the shaft 12. .Again, it will befobserved that this axial adjustment; of "the: cam! is] entirely independent of its angular. adjustment 'and the action can be modified .hy ch gesfindesign ofthebellcrank levers-without afiec'ttag angular adjustment of the cam. i

pqn an increase in en ine speed, thecentrifugal to the axis of the shaft 12. In other words, outward movement of the breaker arm 16 resulting from engagement between the rubbing block 3-2 and high points of the cam surface takes place later and terminates earlier than at slower speed, thus resulting in an increase in the duration of closure of the contacts 20* and 22 measured in degrees of rotation of shaftlZ.

Referring now to the embodiment of the invention illustrated in Figures 7-11,' the basic structure is similar and the same reference numerals are appliedto identical parts and these parts will not be furtherdescribed.

In this embodiment of the invention a modifiedcam device indicated generally at 80 is employed, The cam device in this case is intended to be rotated by the shaft 12 but its adjustmentrelative. to the shaft in response to changes in speed is in this case limited to axial displacement on the shaft. For this purpose the cam device tit) includes a plate. 81 at the lower end of atubular sleeve 82 extending downwardly below the "c'ambody 84. 'The shaft 12'isp'rovided with the bell'crank lever '70" as previouslydesc'ribed, having the arm78' engage able with the lower side o-f'the plate 81' to'eifect vertical movement of the cam device upon radial movement ofthe centrifugal weights 48; In order to drive the cam and at the same time to prevent relative angular movementbe tween the cam device and shaft, theshaft 12 is provided with'alcross pin 86 as best seen in Figure 8, the pin being slidably received in slots 88 provided at thejinterio'r of the sleeve portion 82. I I

Since only vertical adjustment of the cam device is contemplated, it isfpossible to omit the" structurecorrespending to the pin 62 and slot'64 as seen in Figured, and accordingly the centrifugal weights are eachjirovided with brackets 90 including acentrifugal eye slidable over the cross shaft 42 and a single laterally extending arm 94 having a forwardly extending portion 96 provided with an elongatedslot .93 to receive the actuating arm 74 of the bell crank lever 70. 1

Referring now to, Figure? there is illustrated a suitable shape forfthc cam body. 3.4 1.11 will be, recalled that upon an increasein speed'o-f the drive sh'aftfl2 the cam body movesjvertically upwardly 'andaccordingly the portion of the pc'riphery'of'thecam body which;'is e1}- gaged by therubbi'ng block 32 is nearer to the v bottom. As seen in this figure, the'bot't'om of the cam is indicated at 100 and the. top surface. at 1.02. The surfaces 104 constitute cariimin'g surfaces separated "by; flat area's 106 7 intermediate the camrning area. It will be. observed that weghts48 move. iadially. outwardly relative to the drive. a

the. camming areas. have morefangulai: eitte'ntTadjacent thefbottomth'er'eof'andfhenee may. be'desigiied tov maintain thefcontacts zti,22'.closed"foi fa longerp'eriod at high speed. f The function of advancing the. spark in conjuno, tion with incr e'asing the duration of contact closure on an increase in speed'm'ay be provided by disposing the camrning surfaces 104 .somewhat'inclin'ed to the axiso f the cam. I The'dr'awings andtlie. foregoing specification constitute a description ofthe improved ignitiondistributors in, such full, clear, concise and exact terms as to enable anyperson skilled in the art to practice the invention, the scope of which is'indicated byftheappended claims. L

'Whatjl claim. as my inventionv is: V

'1. Anignition distiibutor fol-I an internal combustion enginev comprising a drive shaft" adapted vto bedti-ven. at speeds dependent onengine, speed, a camcartied byisaijd drive shaft for rotationtherewith and forjlimited. adjust ment relative thereto, said cam being in theiforrn. of a regular prism having the outer surfaces. of itslo'bes modified .'-to be of. concentric circular cross-section of progressively varying .radius axially of, said. can,

s'wi'tl'i in 'the'ignit'ion'circuit including contacts, abreaken arm on which oneof said contacts is mounted, a fol lower on said breaker. arm, said cam having lobesoperable to move said breaker. arm ftorseparate saidswitch eon tacts, -said cam" having lobesl'ehapedtoincreasel'th of closure of said contacts and to advance the instant of closure relative to the rotational position of said shaft, and means responsive to variations in shaft speed to adjust said cam.

2. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited adjustment. relative thereto, said cam being in the form of a regular prism having the outer surfaces of its lobes relieved to occupy portions of a single conical surface coaxial with said cam, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, said cam having lobes operable to move said breaker arm to separate said switch contacts, said cam having lobes shaped to increase the period of closure of said contacts, and to advance the instant of closure relative to the rotational position of said shaft, and means responsive to variations in s'haft speed to adjust said cam.

3. An ignition distributor for an internalcombustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a' switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said'breaker arm, and means responsive during engine operation to variations in shaft speed for effecting simultaneous limited angular and axial adjustment of said cam.

4. A distributor as defined in claim 3 in which said breaker arm is mounted for rocking movement about an axis parallel to the axis of said shaft, and said cam is a symmetrical pyramidal body.

. 5. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the'ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said drive shaft, centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed to said cam, first means connecting said plate and said members to effect angular adjustment of said plate relative to said drive shaft upon radial movement of said members, and second means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members.

6. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at-speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contactsis mounted, a cam follower on I said breaker arm, a cross shaft carried by said drive shaft,

centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed tosaid cam, first means connecting said plate and said members to effect angular adjustment of said plate relative to said drive shaft upon radial movement of said members, and second means independent of said first means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members.

7. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said drive shaft, centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed to said cam, first means connecting said plate and said members to effect angular adjustment of said plate relative to said drive shaft upon radial movement of said members, said first means comprising pin and slot connections located laterally from said cross shaft and drive shaft, and second means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members.

8. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said drive shaft, centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed to said cam, first means connecting said plate and said members to effect angular adjustment of said plate relative to said drive shaft upon radial movement of said members, and second means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members, said second means comprising levers pivoted to said drive shaft having arms operatively connected to said members and to said plate.

9. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said drive shaft, centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed to said cam, first means connecting said plate and said members to effect angular adjustment of said plate relative to said drive shaft upon radial movement of said members, and second means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members, said second means comprising bell crank levers pivoted to said drive shaft having arms operatively connected to said members and to said plate.

10. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent-on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said drive shaft,

centrifugal members movable radially on said cross shaft in response to changes in drive shaft speed, a plate fixed to said cam, first means connecting said plate and said members to effect angular adjustment of said plate rela-' tive to said drive shaft upon radial movement of said members, said first means comprising pin and slot connections located laterally from said cross shaft and drive shaft, and second means connecting said plate and members to effect axial adjustment of said plate relative to said drive shaft upon radial movement of said members, said second members comprising levers pivoted to said drive shaft having arms operatively connected to said members and to said plate.

11. An ignitiondistributor for an internal combustion engine comprising a drive shaft adapted to be driven at speeds dependent on engine speed, a cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a switch in the ignition circuit including contacts, a breaker arm on which one of said contacts is mounted, a cam follower on said breaker arm, a cross shaft carried by said driveshaft, centrifugal members movable radially on said cross shaft'in response to changes in drive shaft speed, a plate fixed to said cam, a bracket carried by each of said members having a pair of arms extending toward said drive shaft and spaced laterally therefrom, pin and slot connections between corresponding arms carried by said brackets and said plate to provide limited angular adjustment of said plate relative to said drive shaft upon radial movement of said members and to transmit driving torque to said plate in all positions of angular adjustment while providing for independent axial adjustment of said plate, and levers pivoted to said drive shaft having lever arms operatively connected to the remaining arms of said brackets and to said plate.

12, In combination, a drive shaft adapted to be connected. to an internal combustion engine for rotation therewith, a timing cam carried by said drive shaft "13. In combination, a drive shaft adapted to be con- .nccted to an internal combustion engine for rotation therewith, a timing'cam carried by saiddrive'shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a cross shaft carried by said drive shaft, centrifugal members carried by said cross shaft for movement radially of said drive shaft in accordance with changes in speedrthereof, and independent means connecting said members andsaid cam for effecting' angular and axial adjustment thereof relative to said drive shaft, the means for eifecting angular adjustment of the cam comprising pin and slot connections between said members and said cam located laterally of'said'drive shaft and said cross shaft and effective to transmit driving torque to said cam in all positions of angular adjustment. 14. In combination, a drive shaft adapted to be connected to an internal combustion engine for rotation therewith, a timing cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a cross shaft carried by said drive shaft, centrifugal members carried by said cross shaft'for movement radially of saiddrive shaft in accordance with changes in speed thereof, and independent means connecting said membersand said cam for effecting angular and axial adjustment thereof relative to said drive shaft, the means for effecting axial adjustment of thecam comprising levers pivoted to said drive shaft having arms operatively connected to said'members and to said cam.

"15; In combination, a drive shaft adapted to be connected to an internal combustion engine forrotatiorr therewith, a timing cam carried by said drive shaft for rotation therewith and for limited angular and axial adjustment relative thereto, a cross shaft carried by said drive shaft, centrifugal members carried by said cross shaft for movement radially of said drive shaft in accordance with changes in speed thereof, and independent;

and said cross shaft and effective to transmit, driving torque to said cam in all positions of angular adjustment,

the means for effecting axial adjustment of the cam comprising levers pivoted'to said drive shaft having arms operatively connected to said members and to said cam.

16. Structure as defined in claim 12- in which said;

cam has the form of a truncated pyramid. 7 a v 17, Anignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven atf speeds'dependent on engine speed, a switch in the ignition circuit o-f'said' engine including a movable arm adjacent said shaft having a'switch contact thereon, -a-can1 carried by said shaft for rotation therewith and for axial adjustment thereon, a cam follower on said arm engageable with said cam, a cross shaft carried by said drive shaft, centrifugal'members movable radially on said cross shaft in response to changes in drive shaft speed, levers pivoted to said drive shaft having arms operatively connected'to said members and to said cam to adjust said cam axially of said drive shaft upon a change in engine speed.

18.. An ignition distributor for an internal combustion engine comprising a drive shaft adapted to be driven at speedsdep'endent on engine speed, a switch in theignition circuit of said engine including a movable arm adjacent said shaft having a switch contact thereon, a cam carried by said shaft for rotation therewith and for axial adjustment thereon, a cam follower on said arm engageable with said cam, a cross shaft carried by said driveshaft, centrifugal members movable radially on saidcross shaft in response to changes in drive shaft speed, levers pivoted to said drive shaft having arms operatively connected to said members andto said cam to adjust said cam axially of said drive shaft upon a change in engine speed, said cam having the form of a regular prism having eachof its lobes relieved an increasing amount from one end thereof to the other. i J

References Cited in the file of this patent UNITED sTArns PATENTS 2,832,864 Rapp Apr. 29. 1958 Maugham.

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