US 2977778 A
Description (OCR text may contain errors)
April 4, 1961 R. R. B. BACKLUND ET A1. 2,977,778
AUTOMATIC IIMING DEVICE FOR ENGINES Filed 001'.. 9, 1959 pression ignition type;
i taken ,on the line II-II of Fig. 1; and j y LFig. 3 is a similar view taken on the line I II--III 'of VFig. 1.
2,977,778 AUTOMATIC TIMING DEVICE FOR ENGINES Firedocna, 19459., ser. No.js4s,444 a s claims. (ci. 6ta-2st This invention relates't'o a coupling device between a driving-fshaft andi a `driven shaft including means through which the angular relationship between the two shafts'varies automatically within limits` as a function of the speed of rotation of the shaft.
lThe ensuing description is directed particularly to the automatic'regulation of the advance in cyclic timing of the injection pumps of a diesel engine. However, the timing of other types of engines can be varied by the device as will be apparent upon an understanding of the invention. 4.
It is well recognized that the etiiciency and economy of an internal combustion engine depends upon the time of firing with'relation to crankshaft position and `that it is desirable to vary this time as the `speed of; operation of'the engine varies. Devices for automatically varying the time of tiring or the time of injection in a compression ignition type engine are known and usually comprise system for connecting two shafts including weights adapted to move away 'from eachother under the iniiuence of centrifugal force and against an opposing resilient action, the angular relationship between the two shafts being modified in response to movement of the weights. In presently known devices designed 'for this purpose, undesirable pulsations are created by cyclic forces of the engine and reactionary forces are brought about by sudden changes in engine speed which cause an undesirable reverse action resulting in erraticY engine performance. An unusual amount of frettingbetween the metal parts of such devices which interferes with the smooth satisfactory functioning of the devices is also experienced. f
- It is the object ofthe present invention to provide fan automatic timing device for engines or the like which overcomes the aforementioned deficiencies of existing devices and which provides means for eiecting hydraulic `damping of iiyweights as they move in two directions responsive to acceleration and deceleration of the shaft speedV and also to provide novel means for reducing friction and fretting of the moving parts through their design and through adequate lubrication and a balance of hy-y draulic pressures within the device. l y
f Further and more specific objects ofthe invention reside in the construction andparticular arrangement 'of its several components and are made. apparent in the following specification wherein reference -is made to `the accompanyingA drawings illustrating the invention in a l preferred form.
In the drawings:` Y 1 Fig. 1 is a central verticalse'ction through anauto matic timing device embodyingthe present inventionand illustrating its connection withA the fuel injection pump engine of the comcam shaft of an internal combustion Fig. 2 is a sectional view Vwith'parts brokenaway In Figi of the drawings. ldrive means forafuel in- .i
United States Patif -jection cam shaft is shown as comprising a gear 10 which is engine driven through a gear train not shown and in the present instance is illustrated as also connected with and imparting rotation to a power take-ott shaft represented at 11. The gear 10 drives a fuel injection cam shaft shown at 12 whichY drives a fuel injection pump for each of the cylinders of the engine, one of such pumps being illustrated aty 13 as having a cam follower 14 engageable. with a cam 15 on a shaft12.
lt is to the drive between the gear 10 and the cam shaft 12 that the present invention is directed. The gear 10 carries, as shown in Figs. l, 2 and 3, a yweight housing 16 or" cylindrical shape on its outer diameter and having atsubstantially rectangular chamber as shown at 17 for the reception of a pair of ilyweights 18` disposed for radial sliding movement in the chamber 17. The housing 16 is secured to the gear 10 as by cap screws such as shown at 19 in Figs. 2 and 3 and a recessed cover plate 2li issecured to the member 16 as by cap screws 21. The recessed cover plate 20 contains a disc 22 formed on or non-rotatably secured to a shaft 23 which is piloted in the gear 16 as by a bearing illustrated at 24fand suitably supported in a bearing 2S adjacent its oppositeend.
-This shaft 23 is coupled-to the cam shaft: 12 as by a shaft to which it is coupled upon rotation of the gear 10, the yweights 18 are .provided withangularly disposed cam slots 2S which slidably receiveblocks 29.carried by pins 30 which project from the face of the disc 22. The -tlyweights 18 are biased inwardly toward the center of the chamber 17 by springs 32 and upon acceleration of the engine to high speed operation the weights move outwardly underV theV influence of centrifugal force `against the force of the springs 32. As a result of this outward movement, the cam slots 28 acting on'the slide blocks 29 f then, through the pocket which receives the springs 32,
into those portions of the chamber17 which are disposed effect adjustment of the phase position of the yweights and disc 22 to advance the position of the cam shaft from 6 to 10 depending upon the particular design of the mechanism and speedof the engine and this advancing of the timing provides improved acceleration, more efficient fuel consumption and a higher engine output.
In order to prevent sudden movement of the iiyweights in response to-quick acceleration or deceleration, a supply of oil under pressure, preferably from the engine lubricating oil system, is introduced to the chamber 17 through anaxial bore 34 in the power takeoff shaft and through a bore 3S and connecting radial passage 36 in the shaft 23. The oil passes further through radial passages 37 in the ilyweights 18 asbest shown in Figs. l tol 3 and radially outwardly of the ilyweights. Consequently when theflyweights 18 move radially either inwardly -or outwardly, this :oil must p ass through'the restrictedv passages n 37 and has a damping eifect to prevent sudden'or erratic u smaller in diameter than the interior of the member 20 motion whichY would be transmitted to the cam shaft 12. i
The disc 22 as best illustrated in Fig. l is slightly by which it is housed and is lspaced from the member 20 to permit oil in the chamber 17' to occupy the spacev behind it. Thus upon outward movement of the ilyweights pressure on the face of the disc which is exposed in the chamber 17 iscommunicated also to theopposite side of the disc to relieve a tendency of the discto bind against the housing and thus also contribute smooth operation of a device.' Y
vr1. In an automatic timing devicerfor engines having a rotatable shaft as a partof the engine timing mechanism and arctatable member fordrivingy means to to the desiredl I vary the phase positions of said shafts in response to their rotary speed comprising a iiyweight chamber carried by the driving member, a pair of flyweights in said chamber, driving pins disposed in cam slots between the yweights and the timing mechanism shaft to advance the timing when the ilyweights move outwardly in response to acceleration, resilient means to resist outward movement of the iiyweights, and uid damping means to damp their outward movement.
2. In an automatic timing device for engines having a rotatable shaft as a part of the engine timing mechanism andV a rotatable member for driving said shaft means to vary the phase positions of said shafts in response to their rotary speed comprising a yweight chamber carried by the driving member, a pair of yweights in said chamber, driving pins disposed in cam slots between the yweghts and the timing mechanism shaft to advance the timing when the yweighs move outwardly in response to acceleration, resilient means to resist outward movement of the yweights, and uid damping means to damp both the outward and inward movement of the yweights.
3. An automatic timing device for use between aligned driving and driven shafts which actuate the timing mechanism of an engine comprising a iiyweight chamber carried by the driving shaft, a pair of iiyweights disposed for opposite radial sliding movement in said chamber, a disc on the driven shaft, drive pins on said disc, and said yweights having cam slots receiving said pins whereby outward movement of the yweights in response to acceleration will advance the phase position of the driven shaft, means to supply fluid to said fiyweight chamber, and means to .restrict the flow of fluid past the yweights as they move radially in the chamber.
4. An automatic timing device for use between aligned driving and driven shafts which actuate the timing mechanism of an engine comprising a yweight chamber carried by the driving shaft, a pair of yweights disposed for opposite `radial sliding movement in said chamber, a disc on the driven shaft, drive pins on said disc, and said yweights having cam slots receiving said pin whereby outward movement of the yweights in response to acceleration will advance the phase position of the driven shaft, said flyweights and said disc being enclosed in a fluid tight housing, means to supply a damping uid under pressure to said housing, and means to communicate said fluid to the surface of the disc opposite the iiyweights to balance the thrust effect of the pressure.
5. A device for automatically-changing the phase position of a rotary driving member and a shaft driven thereby in response to their rotary speed comprising. a yweight chamber carried by the driving member, a pair of yweights in said chamber, driving pins disposedin cam slots between the yweights and they timing mechanism shaft to advance the timing when the yweights move outwardly in response to acceleration, resilient means to resist outward movement of the yweights, and fluidl damping means to damp their outward movement.
References Cited in the tile of this patent UNITED STATES PATENTS 1,029,026 Newman June 11, 1912 1,579,287 Duten s Apr. 16, 1926 1,957,181 Mitchel ,g- May 1, 1934 2,722,813 Aldiner .n ,.,.v Nov. 8, 1955l