Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H15/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members
  • F16H15/48—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members with members having orbital motion
  • F16H15/50—Gearings providing a continuous range of gear ratios
  • F16H15/503—Gearings providing a continuous range of gear ratios in which two members co-operate by means of balls or rollers of uniform effective diameter, not mounted on shafts

Definitions

• the invention relates to a transmission mechanism of the type defined in the introductory portion of claim 1.
• the axial shiftings of one or the other set of rolling paths must result in such changes of the mutual positions of the balls and the rolling paths that the transmission ratio of the mechanism continuously changes with the shiftings.
• the US Patent Specification 2862407 discloses a transmission mechanism of the present type in various embodi ments, which share the feature that one set of rolling paths has rectilinear generatrices, while a single one has convex generatrices.
• the tangential forces forming part of the torques transmitted by friction roll gears are the normal force multiplied by the coefficient of friction, the normal forces must be of a size ten times the force which multiplied by the power arm constitutes the moment transferred.
• the invention consists in the finding that the establish ment of a constant axial distance between both the inner and the outer rolling paths makes it possible, on the basis of simple considerations and desired data, to calculate such dimensions and shapes of the constituent elements as will allow the contacts of tangency required for transmission of torque to be maintained within a variation range which makes the transmission mechanism generally applicable for the performance of transmission tasks in practice.
• both the rotation of the balls about their individual axis of rotation and their rotation about the main axis are utilized for transmission.
• the circumstance that the individual axes of rotation always intersect the rolling paths or imaginary inwardly extending extensions of them within the ball points of tangency ensures that the balls will not assume a position in which they only rotate about fixed individual axes of rotation.
• the rolling paths in the transmission mechanism of the invention have generatrices which are symmetrical in pairs, as stated in claim 4.
• the greatest variation width can be obtained when the four rolling paths have double-symmetrical generatrices, as stated in claim 5.
• figs. 1 and 2 show an axial section of an embodiment of the ball gear of the invention in a neutral position and an extreme position, respectively,
• fig. 3 shows the balls in such a gear, as seen in the direction of the gear axis
• figs. 4 and 5 are geometrical figures serving to explain the operation of the gear
• fig. 6 is a horizontal section through the centres of the two lower balls in fig. 3,
• figs. 7-13 show geometrical figures serving to explain the operation of the gear
• fig. 14 is a schematic axial section of the upper half of a gear like the one shown in fig. 1,
• figs. 16a and b are a survey of various gear types of the invention.
• fig. 17 is an axial section like the one shown in fig. 2, but with the gear in the opposite extreme position,
• figs. 18 and 19 are spatial views serving to illustrate the radii used in the calculation of the transmission ratio of the gear
• fig. 20 schematically shows a development of a part of the ball gear and serves to illustrate directions of rotation
• figs. 21-27 are geometrical figures used in the calculation of the transmission ratio
• figs. 28 and 29 show the two ball rings in a gear of the invention in a limit position as seen from the side and in the direction of the gear axis, respectively,
• figs. 30-52 are geometrical figures serving to illustrate certain limits of gears of the invention.
• figs. 33-38 are schematic axial sections of various variants, or parts of them, of the ball gear of the invention.
• the transmission mechanism shown in figs. 1 and 2 has an input shaft 10 which receives power marked by an arrow 11 and mounts two moulding rings 12 and 13.
• Two other moulding rings 14 and 15 are mounted around and coaxially with the rings 12 and 13 and are spaced from these in a radial direction by ring-shaped spaces 16; one 14 is stationary as shown by hatched areas 17, while the other 15, spaced from the first one in an axial direction by a space 23, is freely rotatable but not slidable axially and forms the output element from which the power marked by two half-arrows 18 is taken.
• the four moulding rings 12, 13, 14 and 15 are formed with rolling paths 19, 20, 21 and 22, respectively, which face toward each other and have circular arc-shaped cross-sections in the embodiment shown.
• Axial shifting of the inner moulding rings 12 and 13, as shown in fig. 2, changes the quantities which determine the ratio of the rotary speed of the input shaft 10 to that of the output element 15, i.e. the gear ratio of the transmission mechanism.
• the contacts of tangency between the rolling paths and the balls and between the balls must be maintained, and it will be explained below what conditions are to be met in order for this to be possible.
• Fig. 3 shows two ball rings each having three balls A and B, as seen in the direction of the gear axis.
• an axis z is plotted in fig. 3 which is at right angles to both axes x and y.
• equiangular lines P are plotted, representing planes which intersect each other in the x axis and in which the ball centres move with relative axial movements of the ball rings.
• One of the lines P coincides with the z axis.
• the angle between two adjacent planes P hereinafter called the centre angle, is designated ⁇ and depends upon the number n of balls:
• the possibilities of motion for the ball centres while maintaining contact of tangency between the balls might be represented by two circles Cy of the same size, fig. 4, which are so disposed in their respective ones of the two planes as to form end faces of an imaginary cylinder Cy, whose axis is perpendicular to the planes and in which the imaginary rod S will extend between an arbitrary point on one circle and the diametrically opposite point on the other circle.
• the point of tangency of the balls will be the centroid of this cylinder.
• the two planes in which two adjacent ball centres move are not parallel, but form the angle ⁇ with each other.
• the imaginary cylinder Cy and rod S are plotted in three different positions between two planes P.
• the position shown by solid lines is the neutral position in which the two ball centres are equidistantly spaced from the x axis, and the position shown by broken lines is an extreme position in which the difference between the distances of the ball centres from the x axis are as great as possible.
• the position shown by broken lines is an intermediate position. Above the cylinder are shown the projections of the rod on the z axis in three positions.
• cycloid A cycloid produced by rolling a circle having a radius a on a straight line is shown in fig. 7.
• the oppositely directed movements of the ball centres along the edges of the imaginary cylinder and their common axial shifting together with the cylinder can be depicted by two half cycloids in the bisector plane of the centre angle, as shown in fig. 8, where the axis parallel with the x axis and perpendicular to t cylinder axis is designated x'.
• x' the axis parallel with the x axis and perpendicular to t cylinder axis
• the curves can be expressed by the equation x .
• the ball centres can be fixed on these uniform curves symmetrical about the y axis by means of identical curves, which are symmetrical with the first ones with respect to the x' axis, by shifting one pair of curves in relation to the other pair along the x' axis, as shown by broken lines in fig. 9.
• These double-symmetrical curves establish the geometrical basis for the rolling path profiles.
• the curves are plotted on a plane forming an angle of half the centre angle ⁇ with the planes P in which the ball centres can move. The curves must therefore be projected on one of these planes for them to form a basis for the desired profiles.
• the gearing range of the transmission mechanism is determined by the maximum difference obtainable between the radii from the gear axis to the points of tangency between the balls and the rolling paths and the radii from the individual axes of rotation of the balls to the same points of tangency as well as between the radii from the latter axes to the mutual point of tangency of the balls, by shifting of the balls of the ball rings.
• the maximum differences in radii are determined not only by the number of balls, the angle ⁇ and the value of c, but also by the travel radius r of the fundamental cycloid, the radius r may be used in the adaption of the gearing range, as desired.
• the travel radius of the cycloid is defined by
• Fig. 11 shows an example of a travel radius r smaller than the radius a of the imaginary cylinder.
• Fig. 12 shows a view corresponding to fig. 10, where the ball centre paths are circular arcs Ci 1 and Ci 2 with radius R and with their respective centres C 1 and C 2 at the same distance y c from the minor axis or the x' axis and at the same distance x c from and at their respective sides of the y axis, which coincides with the major axis in the solid ellipse E representing the imaginary cylinder in its neutral position.
• the projection on the x' axis of the imaginary rod S forms the minor axis of the ellipse.
• the projection of the rod on the x' axis in the extreme position of the cylinder is designated d.
• the moulding ring 14 is, as mentioned, fixed, while the input power is fed to the moulding rings 12 and 13 , and the output power is taken from the moulding ring 15.
• the use of four moulding rings may be combined in many other ways to provide various transmissions and variation ranges. Some types may also be used as a differential.
• Figs. 16a and 16b are symbolic views of a plurality of different combinations with type designations, and fig. 15 shows the symbols used in these views. In fig.
• 1, 2, 3 and 4 represent the four moulding rings, and in the type designations the figure before the hyphen represents the moulding ring or rings coupled to the input shaft, while the figure after the hyphen represents the moulding ring or rings coupled to the output shaft.
• the two types which have a slanted stroke in the type designation are differential structures, and the two figures separated by the slanted stroke represent the rings coupled to their respective output shafts.
• This figure additionally comprises the new designations a i and a for the perpendicular distances from the points of tangency of the ball A with the rolling paths to the axis of rotation O A of the ball, and b i and b y for the corresponding distances for the ball B. Also introduced are the designations a k and b k for the perpendicular distances from the common point of tangency of the balls to their respective axes of rotation.
• Fig. 19 illustrates the same as fig. 18, but differently, because instead of the two balls it shows the planes P in which the ball centres can move.
• fig. 19 are marked the regulating length d of the ball gear and the distance x from the centre of the double ball ring to the point where the axes of rotation of the balls intersect the x axis.
• the two axes of rotation must necessarily intersect each other on the x axis, as there must be no slipping between the balls or between the balls and the rolling paths.
• the transmission possibilities of a gear can be determined on the basis of the conditions in the extreme positions between which it can be varied in stepless manner.
• the combinations shown in fig. 16 give various possibilities of transmission.
• the combination shown in fig. 17 with the two inner moulding rings 1 and 4, fig. 15, secured to the input shaft, one 2 of the outer moulding rings stationary and- the other outer moulding ring 3 secured to the output shaft.
• This combination has the type designation 14-3.
• Fig. 1 shows the same gear in a neutral position, which is neutral gear, it being readily apparent for reasons of symmetry that the outer moulding ring must stand still just like .the fixed moulding ring.
• a set of equations may be set up for the calculation of b i on the basis of fig. 22, where the distance along the axis of rotation of the ball B from its intersection with the x axis to the centre of the ball is designated 1 B :
• moulding ring 2 times about its own axis of rotation as moulding ring 2 is fixed.
• the ball row B must similarly have moved one revolution. It appears from fig. 18 that a ball in this ring must have moved
• this gear ratio corresponds to reverse gear and is therefore a negative figure. If the number of revol utions in the reverse gear is called -k, (30) may be written as
• the condition relating to the intersection of the ball centre paths just represents a borderline case, where the distance between the major axis of the imaginary ellipse and one extremity of the shifting path of the ball centres is equal to zero.
• This distance called m
• m may, however, be between zero and the distance marked x" in fig. 30.
• the individual variants of the gear can, in addition to the use on the ten different types, be varied in a special manner, the aim of which is to shift the gearing range.
• Figs. 37 and 38 schematically show such a special arrangement of a gear type 14-3 in one and the other extreme position, respectively.
• neutral gear like before, is obtained when the ball centres are disposed in the x' axis; but owing to the different circular arc-shaped cross-sections of the ring tracks neutral is here in one marginal gearing position.
• the regulation extends further to the other side so that an increase in the gearing width to that side corresponds to the restriction to the other.
• the gearing range can in this manner be shifted to one or the other side of the gear ratio scale.
• different ball gear types can be manufactured, each of which covers various sections of the gear ratio scale.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Friction Gearing (AREA)
• Rolling Contact Bearings (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8096646

Family Applications (1)

Country Status (6)

Families Citing this family (4)

Family Cites Families (7)

• 1982
  • 1982-02-18 DK DK71082A patent/DK71082A/da not_active Application Discontinuation
• 1983
  • 1983-02-17 AU AU12228/83A patent/AU1222883A/en not_active Abandoned
  • 1983-02-17 WO PCT/DK1983/000016 patent/WO1983002986A1/en not_active Ceased
  • 1983-02-17 JP JP83500712A patent/JPS59500234A/ja active Pending
  • 1983-02-17 EP EP19830900628 patent/EP0101461A1/en not_active Withdrawn
  • 1983-10-17 SU SU833660553A patent/SU1209042A3/ru active

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events