US2245280A - Driving means for providing cyclic variations of speed - Google Patents

Description

June 10, 1941. I I s KAMMER 3 2,245,280 DRIVING MEANS FOR PRCVIDING CYCLIG VARIATIONS 0F SPEED Filed Feb. 21, 1940 3 Sheets-Sheet 1 June 10,1941. QK MER 2,245,280

DRIVING MEANS FOR PROVIDING CYCLIC VARIATIONS 0F SPEED Filed Feb. 21, 1940 3 Sheets-Sheet 2 June 10, 1941. G. s. KAMMER 2,245,280

DRIVING MEANS FOR PROVIDING CYCLIC VARIATIONS OF SPEED Filed Feb. 21, 1940 5 Sheets-Sheet 3 Patented June 10, 1941 "rear reins DRIVING MEANS FOR PROVIDING CYCLIC VARIATIONS F SPEED George Stephen Kammer, Park Lane, London, England 7 Claims.

The invention relates to driving means for providing a cyclic variation of speed. Although it has been devised primarily for application to sleeve valve engines for the purpose of moving the sleeve valve for opening and closing the ports, it will be readily understood that it may have other applications in practice such as to driving poppet Valves in internal combustion engines or to shuttle races in wide looms, or in fact to any case in which an oscillating element is to be held nearly stationary at one extreme position or where the speed of movement is required to be substantially higher near one end of travel than the other.

In the specification of British Patent No. 506,- 326 I have described and claimed a mechanism for imparting to a sleeve valve the appropriate movements in the axial and peripheral directions to ensure more satisfactory conditions of port opening and closing than usually provided hitherto. A form of port was described and claimed in the specification of British Patent No. 511,479 which was particularly suitable for valves oper ated by gear of this kind.

The present invention provides an alternative form of drive for the sleeve. The sleeve is operably driven by the usual well-known gear comprising an overhung crank shaft and a pin positively connected to the valve and engaged by the crank, the motion being derived from the engine shaft. According to the invention the driving means comprises a pair of gear wheels with preferably equal numbers of teeth but mounted on shafts eccentric to their peripheries. The pitch lines of the gears are circular and the eccentricities may be equal or unequal, the wheels being preferably so set that the furthest point of one wheel from the centre engages the nearest point of the other and vice versa. The gear wheels are held in correct engagement by a yoke or link having bearings concentric with the pitch lines of the wheels. When used for driving a sleeve valve the ports are then opened and closed rapidly, while the movement of the sleeve is comparatively slow during the time when the ports are closed.

Eccentric gears have already been proposed, but the pitch lines were other than circular. It is still impossible in practice to manufacture oval gears of this kind which will operate satisfactorily at high speeds of revolution, since suitable gear cutting machinery has not been devised. Such gears are restricted to comparatively low speeds of a few hundred revolutions per minute.

The accompanying drawings show a form of construction according to the invention as" applied to a sleeve valve internal combustion engine, and therein Figure 1 is a sectional elevation through the driving mechanism and associated parts,

Figure 2 is an exploded perspective View of the gears and yoke, and

Figures 3a to 3k constitute a set of diagrams to show the operation. 7

Referring to Figure 1 the crank shaft l and connecting rod 2 are shown broken away. Part of the sleeve valve 3 of the Burt McC'ollum type with ports t is also indicated. A gear wheel 5 keyed on the shaft l drives a gear wheel 6 journalled on a stationary shaft 1. The shaft 1 is supported at one end in the crank case 2! and is fixed at the other end to an end cover 22 attached to the crank case 2i and removable for access to the gearing. The gear wheels 5 and 6 are ordinary circular gears.

The gear wheel 6 is attached by screws 23 to a circular gear wheel 8 running eccentrically on the shaft 1 by means of roller bearings 24. The gear wheel 8 meshes with a second gear wheel 9 having the same number of teeth. The gear wheel 8 has short hubs I0 and H concentric with its pitch line, and the gear wheel 9 similarly has short hubs l2 and I3.

Two yokes l5, seen better in Figure 2, are journalled on the hubs iii, ll, l2 and It by means of roller bearings Id. The yokes keep the gear wheels in correct engagement at all times. A shaft 16 projects outwards from the gear wheel 9 parallel to the shaft 1, and a roller ll journalled on the shaft 15 by roller bearings engages the internal faces of a vertical slide it formed on the inside of the cover 22. The position of attach ment of the shaft lE'on the gear 9 is determined by the required eccentricity of the gear.

The gear wheel 9 is formed with a socket 25 in which a slider 25 can move parallel to the axis of the ear. The slider has a spherical seating to engage a spherical member It mounted on a pin 26, which is attached to the sleeve 3.

In operation the gear wheel 6 is driven at a uniform speed and with it the gear wheel 8. On account of the eccentricities of the gear wheels 8 and 9 the latter rotates at a speed varying throughout one revolution but repeating its variation in a similar manner at each revolution. The wheels 8 and 9 are held in. mesh by the yokes l5, and, since the wheel 9 is constrained by the slides l8 acting on its shaft It, the yokes will carry out an oscillation of the same period as the rotation of the gears. The pin 26 of the sleeve 3 will have a pronoun'ceddwell at its up r deadcentre while moving rapidly through the lower part of its travel.

Figures 3a to 370 form a set of diagrams showing the movement obtained with a particular set of dimensions. The larger circles marked 8 and 9 represent the pitch circles of the gear wheels 8 and 9. The smaller circle inside 8 has its centre at P, the centre line of the shaft 1., and touches the circle 8 so as to indicate clearly the eccentricity of the latter. The smaller circle inside 9 similarly shows the eccentricity by having its centre at O, the centre line of the shaft [6, and by touching the circle 9.

If the mechanism has started with the centres of the circles 8 and 9 on the vertical line joining the centres O and P and the eccentricities both downwards, Figure 3a shows the positionafter the gear 8 has moved through an angle of clockwise. The point C represents the axis of the socket and consequently of the pin 20, and the movement of the point C in the various diagrams reproduces the movement of the sleeve.

Figures 3b and show the position after 30 and rotation of the gear 8 respectively. It will be noted that although the point C has moved a little to the left, representing a rotation of the sleeve on its axis, the vertical position of the point has remained unaltered. Even in Figure 3d showing the position after movement of 8 the downward movement of the point C is barely perceptible on the scale of the drawings.

Figure 3e showing the position after rotation of 8 gives the first appreciable downward movement of the point C, viz. 2.5 units. measurement is based on gears 8 and 9 having pitch line diameters of 60 units each and eccentricities of 10 units each, and a throw of 20 units for the point C, i, e. a total vertical travel of 40 units.

After movement of the wheel 8 a sinusoidal drive would give a vertical movement of 20 units for the point C, whereas Figure 3 shows that the actual movement is only a quarter of this amount, viz. 5 units. After this point the vertical movement gradually becomes more rapid. Figure 3g shows a movement of 8 units for Figure 371. one of 13.5 units for and Figure 37' one of 20.8 units for Actually with the proportions used as a basis for Figures 3a to 3k the half way position of 20 units is reached after a rotation of the wheel 8 through 132 30.

Figure 370 shows a continuation of the rapid downward movement of the point C which has here reached 28 units with rotation of the wheel 8. The position at will be clear without a diagram and at the point C reaches its lower dead centre at 40 units. Thereafter the upward movement of the point C is similar, reaching a point within 5 units of its top position at an angular movement of 270 corresponding to Figure 31.

The operation of the gear may be summed up by saying that the true axis of the gear 3 carries out a rotary movement about the axis P and that of the gear 9 about the axis 0. The axis 0 is as shown in Figures 1 and 2 constrained to move up and down in a vertical plane and forms the axis of rotation for the pin 20 of the sleeve.

The speed characteristics can be varied by varying the eccentricity of either or both of the wheels 8 and 9 on their axes P and O. In an extreme case the pin 29 could be made to remain at its upper position for the greater part of a cycle and to carry out its travel downwards This 1 and return within 100 of rotation of the wheel 8. This may not be of interest for driving sleeve valves in engines of the kind referred to, but could be advantageously applied to poppet valves. The valves would then be positively driven in both directions, and the engine speed would no longer be limited by the operation of a spring return for the valves.

Although in the example described the axis 0 was caused to move directly towards and away from the axis P, this is not necessarily the case. The path of the axis 0 may be non-planar and such a movement may be effected by link gear attached to the shaft I6 or to a point on the yoke. The link gear may comprise a single link having its other end moved by an eccentric, so that an additional component of movement is impressed on the axis 0.

What I claim is:

1. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear Wheel, bearings on the gear wheels concentric with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached eccentrically to the second gear wheel, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and means for imparting the movement of the second gear wheel to the driven member.

2. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear wheel having the same number of teeth as the first, bearings on the gear wheels concentric with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached eccentrically to the second gear wheel, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and means for imparting the movement of the second gear wheel to the driven member.

3. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear wheel having the same number of teeth as the first, bearings on the gear wheels concentrio with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached to the second gear wheel with the same eccentricity as that of the first gear wheel on its shaft, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and means for imparting the movement of the second gear wheel to the driven member.

l. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear wheel having the same number of teeth as the first, bearings on the gear wheels concentric with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached to the second gear wheel with the same eccentricity as that of the first gear wheel on its shaft, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and means for imparting the movement of the second gear wheel to the driven member, the gear wheels being so set that the furthest point of one wheel from the axis of its shaft engages the nearest point of the other and vice versa.

5. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear Wheel, bearings on the gear wheels concentric with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached eccentrically to the second gear wheel, parallel guides to constrain the second shaft to move directly towards and away from the first shaft, and means for imparting the movement of the second gear wheel to the driven member.

6. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed and a driven member, comprising in combination a shaft driven by the driving member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear wheel, bearings on the gear wheels concentric with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached eccentrically to the second gear wheel, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and a crank pin on the second gear wheel to actuate the driven member.

7. Driving means for providing a cyclic variation of speed between a driving member driven at constant speed anda driven member, comprising in combination a shaft driven by the driv ing member, a circular gear wheel mounted eccentrically on the said shaft, a second circular gear wheel, bearings on the gear wheels concentrio with their respective pitch lines, a yoke engaging the said bearings to hold the gear wheels in mesh, a shaft attached eccentrically to the second gear wheel, constraining means to guide the second shaft in a predetermined path as the distance between the shaft axes varies, and a crank pin on the second gear wheel on the opposite side of the axis of the second shaft to the centre of the pitch line to actuate the driven member.

GEORGE STEPHEN KAMMER.

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