US2899810A

US2899810A - Automatic timing device

Info

Publication number: US2899810A
Authority: US
Publication date: 1959-08-18
Anticipated expiration: 1976-08-18

Description

United States Patent 'O AUTOMATIC TIMIN G DEVICE Earl R. Pierce, Bow, Wash., assignor to General Motors Corporation, Detroit, Mich., a corporation of'elaware .Application January .14, 1957,-,Serial No. 634,107

7 Claims. (Cl.f64-`,25)

This invention relates to means for varying the angular relationship between a driving Shaft and a driven shaft,

.for automatically varying the timing of the injection or ing devices for such vengines are well known and generaln ly include a speed sensitive vdevice operable to Vmechani- Vcally or hydraulically shift the timing relationship between two 4shafts. In general, however, the known devices lare rather complicated, lexpensive in construction, and lack sensitiveness in operation.

This invention is directed to means 'for automatically vvarying the rangular relationship'between a driving yshaft and a driven shaft, particularly suitablej'for use as an injection timing means, but also suitable for other analogous purposes. Among the principal objects of lthelinvention are to provide a new and Vimproved devieeffor automatically varying 'the angular Irelationship,`betw een such shafts; vto provide a new and improved automatic timing device for mechanically adjusting the timing of fuel injection apparatus in accordance with engine'speed;

to provide a timing yc'lev'ice'of the type vsetforth which is relatively` simple, rugged and economical in construction and adjustment; to provide 'an automatic `timing device which will yalter thertime of beginning of'fuel injection according tothe engine speed requirements 'to give limproved fuel'economy'and engine performance; `to provide such a device which is highly responsive'to yspeed changes and positive in action; and'to provide vsuch-a device eliminating the necessity of highlyprecisioned, expensive 'elevments as required in prior timing devices. v

The foregoing and other objects, advantages `and features of the Lpresentinvention 'will :beapparent from the following 'description having reference to theaccompany ing drawing in which 7"the single'iigure'is taken substantially inlongitudinal section but with portions thereof Yshown 1n elevation to Showthe details o`f-construction-of a preferred illustrative embodiment fof 4a ltiming device. constructed in accordance with the invention.

Referring lmore particularly to :the single'gure of '.the drawing, an engine housing or frame isgpartially shown at 2 and `rotatably vmounts' a drivingnshaft 4 ,and acamshaft 6 in axially. alignedand spaced relation.k yA timing vgear 8.is secured 'to `the driving .shaft v4 `adjaeentits .endopposite the camshaft and Vengages a gear .10 which .is journaled in the frame 2 and is rotatably'driven-by anengine driven quill .shaft 1.2.` rAnfautomatic .timing :device or -coupling iconstructed in accordance with the .invention drivingly interconnects zthe adjacent ends of 4the'shaft 4 Vandfcamshaft lgthe camshaft being adapted'to actuate vlassociated fuel .injection -mechanism to -sequentially inject controlled .quantities of 'fuel into the several combustion chambers of the engine. v v

The timing device includes a spider member 14 which is secured to .the end'of the shaft 4 opposite the timing gear `8 by .tapered splines 15 and a nut 16. The spider member 14 has a plurality of axially projecting lugs or dogs, one of which is shown at 18. These dogs drivingly engage a plurality of cooperating radially spaced and extending slots 20 formed in an annular coupling member .22 having aplurality of similar intermediate slots 24 drivingly ,engaging axially projecting lugs or dogs `26 formed on a second annular coupling member 28. The coupling member 28 is adjustably secured to ,an annular llange30 of ,a member 32by aplurality of radially spaced bolts 34 which -are threadable in the member '23 and project Athrough cooperating arcuate slots or holes .36 formed in the member 32. This arrangement pennits manual adjustment of the angular relationship .between 'the coupling member 28 and the flanged member 32 and thereby between the driving shaft '4 and the camshaft 6 to compensate Vfor variations in injection timing required by `various 'fuels by first loosening the bolts 34, then making the necessary angular adjustment in the driving connection and subsequently Vretightening the bolts.

'Ihe Amember 32 has a cylindrical hub portion 38 which is helically and externally splined as indicated at 4i). These helical splines 40 slidably coact with similar splines 42 formed internally of and adjacent one end of a `coupling Sleeve 44. The opposite .end of the coupling sleeve 44 is provided with vsimilar internal helical splines 46 of opposite hand which slidably coact with external helical splines 48 'formed on a cylindrical Yportion '50 of a weight carrier 52 of a speed responsive centrifugal mechanism V54. Due to this use of splines of opposite hand, longitudinal shifting of .the sleeve 44 causes relative rotation between the coacting splined members and thereby between 'the shaft '4 and camshaft 6. In the preferred 'illustrative embodiment, the several oppositehand splines are of equal jpitchjthereby dividing the slidingresistance imposed on each end of the coupling sleeve. l However, such splines might be of dilerentpitchtoprovide for difvfering rates of Vangular adjustment with a given speed responsive mechanism ,54. The weight carrier 52 is secured to .the camshaft'by 'tapered splines 56 adjacent one end thereof and by a cylindrical nut member'SS. The nut Amember-58 extends` axially of andsupports the .oppo site end vof the cylindrical weight carrier portion 50 which in -turn vsupports the hub portion of the member 32. for rotation relative thereto. A plurality of paired arms 60 are carried by the camshaft end of the weight carrier 52 and pivotally mount, as indicated at 62, a plurality ofbellcrank-shaped centrifugal weight`64. An arm portion 65 extends inwardly `from each of theouter weight portions 66 of theweights 64'and thrustably engages a bearing ring 68 carried by Vthe/adjacent end of the coupling sleeve 4.4 in 'opposition to aspeeder spring 70 which is .compressively and torsionally interposed between an annular spring seating retainer 72 carriedby the opposite end of thecoupling sleeve and the ilange `of themember 32.

The ends A,of theespeeder spring 7llare ofa configuration to provide a 'balancedthrust coaxial ofthe spring seating members. An 'initial biasing action is imposed on the'speeder'spring l'70 vand tends 'to compressivelymaintain the ends thereof. in non-rotative frictional engagementwith the spring seating surfaces of the flanged member 32 and the sleeve carried retainer 72. Thisinitial biasing action is laugmented by any speed responsive deection `by thecentrifugal weights 64 and provides aftorsional lash ktake-up action between the several splined elements underengine operating conditions. 'This lash take-up resiliently dampens and prevents the otherwise destructiveimpacting which tends to occur between the l 3 coacting spline teeth due to the rapid and extreme cyclic torque loads imposed on the camshaft 6 by the actuation of the several injector mechanisms.

To assure adequate lubrication'of the timing adjusting device, a passage 74 provided in the driving shaft 4 is intermittently connected as it revolves toa lubrication supply passage 76 in the engine frame. The passage 74 is connected by an O-ring sealed nipple 78 to orifices 80 and 81 in the cylindrical nut member 58 and thereby to a distribution groove 82 intermediate the nut 58 and the cylindrical portion 50 of the weight carrier. The groove 82 is connected by a plurality of ports 84 to a second groove 86 intermediate the rotatably mating surfaces of the hub and cylindrical portions of the members 32 and 52, respectively, from which the supplied lubricant passes outwardly to lubricate the mating surfaces of the splines 40, 42, 46 and 48 and the pivotal mountings 60 of the centrifugal weights 64 through holes 88 provided in the underside thereof. The oil thus supplied to the timing device is collected in a sump 90 provided in the bottom of the chamber 92 enclosing the timing device and is returned to the main sump or lubricant reservoir of the engine through a drain hole 94 and other suitable passages formed in the engine frame.

When the driving shaft 4 is not rotated, or is rotating at a speed below that requiring advancement of the timing fuel injection, the parts are in their positions shown in the drawing; the coupling sleeve 44 being in its extreme left hand position and the Weight portions 66 being in collapsed engagement with the outer surface thereof. As the rotational speed of the shaft 4 is increased, the centrifugal forces acting on the weights increase to a point at which they equalize the initial biasing action of the Speeder spring 70 after which any further increase of the shaft speed results in shifting the sleeve to the right with compressive deflection of the speeder spring until either a new condition of equilibrium is attained with the centrifugal forces or until the spring retainer carried by the coupling sleeve abuts the hub portion of the member 32, as shown in broken lines, thus achieving the maximum desirable advance in injection timing. This speed responsive shifting of the sleeve acting through the helical splines rotates the cam shaft relative to the driving shaft to advance the injection timing. When the speed of the engine and thereby the speed of the shaft 4 is reduced between the speeds establishing the maximum advanced and retarded angular relationships attainable between the shaft 4 and the camshaft 6, the centrifugal and Speeder spring forces coact to permit the return of the coupling sleeve 44 toward the left thereby effecting a rotation of the camshaft 6 relative to the driving shaft thereby retarding the fuel injection timing.

From the foregoing description, it will be apparent that the several aforementioned objects and advantages are attained in the illustrative preferred embodiment of the invention. While the timing means of the invention is particularly applicable toV varying the timing of fuel injection in internal combustion engines of this type, and has been so described for the purpose of illustration, it may be used for varying the angular relationship between any two driving and driven shafts or members. By way of example, the driven shaft may be the member actuating exhaust or intake valves of an engine. Consequently, various modifications may be made from the illustrative embodiment without departing from the spirit and scope of the invention, as defined in the following claims.

I claim:

l. In a device of the character described, a drive shaft, a shaft adapted to be driven by said drive shaft, said shafts being rotatably mounted in spaced coaxial relation, and means for operatively connecting said shafts and adjusting the angular relationship between said drive and driven shafts, said means including a member having a manually adjustable driving connection with one of Said shafts and having a cylindrical portion extending CII coaxially of said one shaft, a centrifugal weight carrier mounted on the other of said shafts and having a cylindrical portion extending coaxially of ysaid other shaft, said cylindrical portions having axially spaced helical splines formed thereon of opposite hand, a sleeve member embracing said splined cylindrical portions and having splines thereon slidably coacting with the splines on said cylindrical portions to adjust the angular relationship between said drive and driven shafts upon axial shifting of said sleeve member relative thereto, a speeder spring compressively interposed between said sleeve member and said first-mentioned member, said weight carrier having a plurality of outwardly extending arm portions and centrifugal weight members pivotally mounted by said arm portions for speed responsive outward movement, and means operably connecting said weight members to said sleeve member whereby said speed responsive movement of said weight members biases said sleeve member in opposition to said Speeder spring.

2. In a means for operatively connecting and adjusting the angular relationship between two shafts, a drive shaft, a shaft adapted to be rotatably driven by said drive shaft, a first annular member secured to one of said shafts and having a manually adjustable driving connection with a second annular member mounted in spaced coaxial relation thereto, said second annular member having an axially extending cylindrical hubvportion, a centrifugal weight carrier secured to said other shaft, said weight carrier having an axially extending cylindrical hub portion, said spaced cylindrical hub portions having spaced helical splines formed thereon of opposite hand, a sleeve member having Isplines thereon slidably coacting with the splines on said hub portions to adjust the angular relationship between said drive and driven shafts upon axial shifting of said-sleeve member relative thereto, centrifugalweight members pivotally mounted with respect to said weight carrier for speed responsive outward movement, a speeder spring compressivelyV interposed between lsaid sleeve member and said second member, and said weight members being adapted to bias said sleeve member axially in opposition to said Speeder spring to thereby automatically adjust the angular relationship between .said ,drive and driven shafts in accordance with the rotational speed of said shafts. ,Y

3. In a governor mechanism of the character described, a drive shaft, a shaft adapted to be rotatably driven by said drive shaft, a rst meansfor manually adjusting the angular relationship between said drive and driven shafts, and a second means for automatically adjusting the angular relationship between -said drive and driven shafts in accordance with the rotational speed of said shaft, said first means including a first member secured to one of said shafts and having a manually adjustable driving connection with a second membersaid second member having a cylindrical portion coaxial with said one shaft, said second means including a helical spline formed on said cylindrical portion, a third member secured to the other of said shafts and having a cylindrical portion in spaced coaxial relation to the cylindrical portion of said second member, said cylindrical portion of said third member having helical splines formed thereon of opposite hand to the splines formed on said second member, a sleeve member having splines formed thereon slidably coacting with the splines on'said cylindrical portions to adjust the angular relationship between said drive and driven shafts upon axial shifting of said sleeve member relative thereto, and a speed responsive means operable to shift said sleeve member axially to thereby adjust the angular relationship between said drive and driven shafts inaccordance wiV the speed kof said shafts.

4. In a governor mechanism for varying the angular relationship between vtwo shafts, a rotatably mounted drive shaft, a shaft adapted to be rotatably driven by said drive shaft, each of said shafts having spaced helical splines of opposite hand carried thereby, a sleeve member having oppositely disposed helical splines formed thereon coacting with the splines carried by said shafts to drivingly interconnect said shafts and slidable with respect thereto to adjust the angular relationship between said shafts, and a centrifugal mechanism including at least one weight member pivotally mounted with respect to one of said shafts for speed responsive outward movement and operably connected to said sleeve member to shift said sleeve member axially upon outward movement of said weights, and means including a spring compressively and torsionally interposed between the other of said shafts thereby biasing said sleeve member in opposition to the outward movement of said weights, and said weight member shifting said sleeve member axially in opposition to said biasing means in response to increases in the rotational speed of said shafts to thereby adjust the angfular relationship between said Shafts.

5. A centrifugal governor for varying the angular relation between two shafts comprising a drive shaft and a shaft adapted to be driven by said drive shaft, said shafts being rotatably mounted in spaced coaxial relation, the adjacent ends of said shafts carrying helical splines of opposite hand, a sleeve member embracing said shaft ends, -said sleeve member having oppositely disposed helical splines formed adjacent each end thereof and slidably coacting with the splines carriedby said shafts to vary the angular relation between said shafts, a Speeder spring compressively and torsionally interposed between one of said shafts and said sleeve member, and a centrifugal mechanism carried by the other of said shafts, said centrifugal mechanism including centrifugal weights pivotally mounted with respect to said other shaft for speedl responsive outward movement and having arms thereon thrustably biasing said sleeve member in opposition to said Speeder spring, said centrifugal weights being adapted to shift said sleeve member in opposition to said Speeder spring in response to increases in the rotational speed of said shafts to thereby adjust the angular relationship between said shafts.

6. In a mechanism for varying the angular relation between two shafts, a drive shaft, a shaft adapted to be driven by said drive shaft, said shafts being rotatably mounted in spaced coaxial relation, said shafts having coaxially spaced helical splines of opposite hand, a sleeve member having helical splines slidably coacting with the splines carried by said shafts to adjust the angular relation between said shafts upon axial shifting of said sleeve member relative thereto, a speed responsive means operable on said sleeve member to shift said sleeve member in response to increases in the rotational speed of said shafts -to thereby adjust the angular relationship between said shafts and spring means compressively and torsionally interposed Ibetween said sleeve and one of said shafts to bias said sleeve member in opposition to said speed responsive means and to take up lash between the coacting helical splines thereon.

7. In a device of the character described, a drive shaft, a shaft adapted to be driven by said drive shaft, said shafts being rotatably mounted in spaced coaxial relation, and means for operatively connecting said shafts and adjusting the angular relationship between said drive and driven shafts, said means including a first member secured to one of said shafts and a second member secured to the other of said shafts, said first and second members having coaxial cylindrical portions telescopically journaled with irespect to each other, said cylindrical portions having axially spaced helical splines formed thereon of opposite hand, a sleeve member embracing said splined cylindrical portions and having splines formed thereon slidably coacting with the splines on said cylindrical portions to adjust the angular relationship between said drive and driven shafts upon axial shifting of said sleeve member relative thereto, a speed responsive means operable to shift said sleeve member axially in accordance with variations in the driving speeds of said shafts to thereby adjust the angular relationship between said drive and driven shafts and spring means compressively and torsionally interposed between said sleeve and one of said shaft to bias said sleeve member in opposition to said speed responsive means and to take up lash between the coacting helical splines thereon.

References Cited in the le of this patent UNITED STATES PATENTS 2,272,726 Sanders Feb. 10, 1942 2,549,749 Spengler Apr. 17, 1951 FOREIGN PATENTS 499,261 Great Britain Ian. 20, 1939