Variable speed transmission

Claim 2

A power transmission apparatus comprising: (a) a body, (b) a pinion gear mounted for rotation about a pinion axis relative to the body, (c) a cam means having curved inner and outer surfaces, the cam means and the pinion gear being mounted for relative rotation therebetween, (d) first and second gear rack pairs, each gear rack pair having oppositely facing toothed gear racks which are spaced apart sufficiently to receive the pinion gear and cam means therebetween when the pinion gear fully engages at least one of the toothed gear racks, and the outer surface of the cam means is generally adjacent at least one of the oppositely facing toothed gear racks, (e) first and second rack support means for supporting the first and second gear rack pairs respectively against lateral movement of the rack pair relative to the respective support means so as to ensure full engagement between the pinion and respective racks sequentially as required, (f) a rotor mounted for rotation about a rotor axis, the rotor having rotor engaging means for engaging the first and second rack support means so as to transmit power therebetween.

Claim 3

A power transmission apparatus as claimed in claim 1 in which: (a) each rack support means has a pair of parallel outer bearing surfaces disposed on opposite sides of the respective rack support means and spaced apart on opposite sides of the pinion, (b) each toothed gear rack has an outer bearing surface disposed on an edge opposite to teeth of the rack, the outer bearing surface of the gear rack being in engagement with an outer bearing surface of a respective rack support means.

Claim 4

A power transmission apparatus as claimed in claim 2 in which: (a) the toothed racks of each pair have oppositely disposed rack end portions, (b) each rack support means has a pair of parallel recesses disposed on opposite .sides of the respective rack support means and spaced apart on opposite sides of the pinion, each recess retaining a respective gear rack and having a respective outer bearing surface to engage the outer bearing surface of a respective gear rack, each recess also having a pair of oppositely spaced recess end portions for receiving the rack end portions of the respective rack.

Claim 5

A power transmission apparatus as claimed in claim 3 in which: (a) each rack recess has a length greater than length of the respective rack retained therein, (b) resilient means cooperate with the rack support means and the rack to resiliently mount the rack for longitudinal movement relative to the respective rack recess.

Claim 6

A power transmission apparatus as claimed in claim 4 in which: (a) the resilient means centers a respective gear rack within a respective recess.

Claim 7

A power transmission apparatus claimed in claim 5 in which: (a) the resilient means includes a resilient member mounted at each end of each rack, each resilient member cooperating with an adjacent end portion of the rack recess so as to apply an inwards axial force to the rack, the inwards force at one end of the rack being opposed by an opposite inwards force from an opposite end of the rack tending to center the rack within its recess.

Claim 8

A power transmission apparatus as claimed in claim 3 in which: (a) each end portion of each recess has an inner edge portion disposed generally oppositely to the outer bearing surface of the rack recess, space between an inner edge portion and an adjacent and opposite outer bearing surface of the respective recess being essentially equal to width of a respective end portion of the rack, so as to essentially prevent the lateral movement of the rack relative to the rack recess.

Claim 9

A power transmission apparatus as claimed in claim 3 in which: (a) the racks have respective thicknesses defined by space between outer and inner side faces thereof, (b) each rack support means has a thickness defined by spaces between opposite side faces thereof, and each recess of the rack support means has a depth less than thickness of the rack support means, each recess having a recess rear face portion which engages an inner side face of a respective rack, the rear face portion having a thickness no greater than difference between the thickness of the rack support means and the thickness of the rack, so that when the rack is received in the respective rack recess, the outer side face of the rack is generally flush with an adjacent outer face of the rack support means.

Claim 10

A power transmission apparatus as claimed in claim 1 in which: (a) each rack support means has oppositely disposed driving sides disposed generally normally to the rack pairs mounted thereon, each driving side having a driving side inner portion and two driving side outer portions spaced on opposite sides of the respective driving side inner portion, the driving side outer portions projecting outwardly further from the respective driving side inner portions relative to the pinion.

Claim 11

A power transmission apparatus as claimed in claim 9 in which: (a) a resultant force vector from contact between the pinion and the respective rack passes closely adjacent a point of contact between an adjacent driving side outer portion and the respective engaging surface of the rotor.

Claim 12

A power transmission apparatus as claimed in claim 1 in which: (a) the pinion gear and gear racks each have teeth, some of which having obliquely inclined tooth tips which generate forces on each other if opposing tooth tips contact each other momentarily prior to full engagement with each other, the oblique forces shifting the rack teeth generally tangentially relative to the pinion teeth immediately prior to engagement so as to facilitate meshing of the teeth.

Claim 13

An apparatus as claimed in claim 11 in which: (a) each tooth with an obliquely inclined tooth tip has a main longitudinal axis, and the tip has a tip end face which is inclined at an angle to the main axis within a range of between 85 degrees and 45 degrees.

Claim 14

A power transmission apparatus as claimed in claim 1 further including: (a) a pinion shaft mounting the pinion gear for mutual rotation about the pinion axis relative to the body, (b) a cam mounting means journalling the pinion shaft and connected to the cam means so that the inner surface of the cam means is at a fixed distance from the pinion gear axis, so as to permit teeth of the pinion gear to clear the inner surface of the cam means during the relative rotation therebetween.

Claim 15

A power transmission apparatus as claimed in claim 13 in which: (a) the body includes inner and outer body sides which are spaced apart sufficiently to receive therebetween the first and second gear rack pairs, the pinion gear and the rotor, the body sides engaging the rotor to permit relative movement therebetween and having aligned central openings to receive the pinion shaft to pass therethrough.

Claim 16

A power transmission apparatus as claimed in claim 13 further characterized by: (a) a gear ratio change means for varying spacing between the rotor axis and the pinion axis so as to vary gear ratio between the pinion shaft and the rotor, the gear ratio change means cooperating with the rotor and the pinion gear, (b) the gear ratio change means including a rotor mounting means which cooperates with the cam mounting means to permit relative movement between the cam mounting means and the rotor mounting means, (c) the rotor being journalled on the rotor mounting means for relative rotation about the rotor axis.

Claim 17

A power transmission apparatus as claimed in claim 1 in which: (a) the rotor has an annular bearing surface concentric with the rotor axis, and the transmission further includes: (b) a rotor mounting means having a rotor mounting surface complementary to the annular bearing surface of the rotor for mounting the rotor thereon, the rotor mounting means being non-rotatably located relative to the cam means.

Claim 18

A power transmission apparatus comprising: (a) a body, (b) a pinion gear mounted for rotation about a pinion axis relative to the body, (c) a cam means having curved inner and outer surfaces, the cam means and the pinion gear being mounted for relative rotation therebetween, (d) first and second gear rack pairs, each gear rack pair having oppositely facing toothed gear racks which are spaced apart sufficiently to receive the pinion gear and cam means therebetween when the pinion gear fully engages at least one of the toothed gear racks, and the outer surface of the cam means is generally adjacent at least one of the oppositely facing toothed gear racks, (e) first and second rack support means for supporting a respective pair of racks, each rack support means having oppositely disposed driving sides disposed generally normally to the rack pairs mounted thereon, each driving side having a driving side inner portion and two driving side outer portions spaced on opposite sides of the respective driving side inner portion, the driving side outer portions projecting outwardly further from the respective driving side inner portion relative to the pinion, (f) a rotor mounted for rotation about a rotor axis, the rotor having four engaging surfaces disposed as a square about the rotor axis, the two driving side outer portions of each rack support means engaging respective engaging surfaces of the rotor to permit relative movement along the engaging surfaces.

Claim 19

A power transmission apparatus comprising: (a) a body, (b) a pinion gear mounted for rotation about a pinion axis relative to the body, (c) a cam means having curved inner and outer surfaces, the cam means and the pinion gear being mounted for relative rotation therebetween, (d) first and second gear rack pairs, each gear rack pair having oppositely facing toothed gear racks which are spaced apart sufficiently to receive the pinion gear and cam means therebetween when the pinion gear fully engages at least one of the toothed gear racks, and the outer surface of the cam means is generally adjacent at least one of the oppositely facing toothed gear racks, (e) first and second rack support means for supporting a respective pair of racks, each rack support means having oppositely disposed driving sides disposed generally normally to the rack pairs mounted thereon, each driving side having a driving side inner portion and two driving side outer portions spaced on opposite sides of the respective driving side inner portion, the driving side outer portions projecting outwardly further from the respective driving side inner portion relative to the pinion, (f) a rotor mounted for rotation about a rotor axis, the rotor having four engaging surfaces disposed as a square about the rotor axis, the two driving side outer portions of each rack support means engaging respective engaging surfaces of the rotor to permit relative movement along the engaging surfaces.

Claim 20

A power transmission apparatus as claimed in claim 17 in which: (a) a resultant force vector from contact between the pinion and a respective gear rack passes closely adjacent a point of contact between an adjacent driving side outer portion and the respective engaging surface of the rotor.

Claim 21

A power transmission apparatus as claimed in claim 17 in which: (a) the rotor has a generally square recess having four sides which serve as the four engaging surfaces which contact driving sides of each rack support means.

Claim 22

A power transmission apparatus claimed in claim 17 in which: (a) the driving sides of each rack support means are generally concave so as to extend smoothly inwardly to the driving side inner portion from the two driving side outer portions thereof.

Claim 23

A power transmission apparatus as claimed in claim 17 in which: (a) the rack support means are generally rectangular, with a pair of oppositely disposed interconnecting sides which interconnect the respective driving sides of the respective rack support means, each rack support means having a thickness, the rack support means being disposed with faces thereof closely adjacent each other, (b) the engaging surfaces of the rotor have a width at least equal to sum of the thicknesses of the first and second rack support means so as to provide adequate engagement therewith.

Claim 24

A power transmission apparatus as claimed in claim 17 in which: (a) each rack support means has a thickness defined by space between opposite side faces thereof, and each recess of the rack support means has a depth less than the thickness of the rack support means, each recess having a recess rear face portion which engages an inner side face of a respective rack, the rear face portion having a thickness no greater than difference between thickness of the rack support means and thickness of the rack, so that when a rack is received in the rack recess, an outer side face of the rack is generally flush with an adjacent face of the rack support means.

Claim 25

A power transmission apparatus as claimed in claim 17 in which: (a) the driving side outer portions have bearing means to reduce friction and wear between the rack support means and the engaging surfaces of the rotor.

Claim 26

A power transmission apparatus as claimed in claim 23 in which: (a) the bearing means includes a roller journalled for rotation relative to the rack support means and adapted to contact the engaging surface of the rotor.

Claim 27

A power transmission apparatus comprising: (a) a body, (b) a pinion gear mounted for rotation about a pinion axis relative to the body, (c) a cam means having curved inner and outer surfaces, the cam means and the pinion gear being mounted for relative rotation therebetween, (d) first and second gear rack pairs, each gear rack pair having oppositely facing toothed gear racks which are spaced apart sufficiently to receive the pinion gear and cam means therebetween when the pinion gear fully engages at least one of the toothed gear racks, and the outer surface of the cam means is generally adjacent at least one of the oppositely facing toothed gear racks, (e) first and second rack support means for supporting a respective pair of racks, (f) a rotor mounted for rotation about a rotor axis, the rotor having rotor engaging means for engaging the rack support means so as to transmit power therebetween, (g) the pinion gear and the gear racks each having teeth, some of which having obliquely inclined tooth tips so as to generate oblique forces on each other if opposing tooth tips contact each other momentarily prior to full engagement with each other, the oblique forces shifting the rack teeth generally tangentially relative to the pinion teeth immediately prior to engagement so as to facilitate meshing of the teeth.

Claim 28

A power transmission apparatus comprising: (a) a body, (b) a pinion gear mounted for rotation about a pinion axis relative to the body, (c) a cam means having curved inner and outer surfaces, the cam means and the pinion gear being mounted for relative rotation therebetween, (d) first and second gear rack pairs, each gear rack pair having oppositely facing toothed gear racks which are spaced apart sufficiently to receive the pinion gear and cam means therebetween when the pinion gear fully engages at least one of the toothed gear racks, and the outer surface of the cam means is generally adjacent at least one of the oppositely facing toothed gear racks, (e) first and second rack support means for supporting a respective pair of racks, (f) a rotor mounted for rotation about a rotor axis, the rotor having rotor engaging means for engaging the rack support means so as to transmit power therebetween, (g) the pinion gear and the gear racks each having teeth, some of which having obliquely inclined tooth tips so as to generate oblique forces on each other if opposing tooth tips contact each other momentarily prior to full engagement with each other, the oblique forces shifting the rack teeth generally tangentially relative to the pinion teeth immediately prior to engagement so as to facilitate meshing of the teeth.

Claim 29

A power transmission apparatus as claimed in claim 25 in which: (a) each tooth with an obliquely inclined tooth tip has a main longitudinal axis, and the tip has a tip end face which is inclined at an angle to the main axis within a range of between 85 degrees and 45 degrees.

Claim 30

A power transmission apparatus as claimed in claim 25 in which: (a) the tip end faces of the teeth are generally straight, and radiused at opposite ends thereof to blend smoothly with adjacent faces of the teeth.

Claim 31

An apparatus as claimed in claim 25 in which: (a) the cam means has an inner curved surface which is concentric with the pinion axis, and an outer curved surface which has a geometrical profile reflecting a locus of points of contact of the cam and the tooth tips of a non-engaged rack sweeping past and contacting the outer surface, while a remaining rack is engaged by the pinion means.

Claim 32

A power transmission apparatus as claimed in claim 27 in which: (a) the tip end face of each pinion tooth has a leading and trailing end portion with respect to direction of rotation of the pinion gear, the leading end portion being at a greater radial distance from the pinion axis than the trailing end portion.

Claim 33

A power transmission apparatus as claimed in claim 29 in which: (a) the cam means has an inner curved surface which is concentric with the pinion axis, and an outer curved surface which has a geometrical profile reflecting a locus of points of contact of the cam and the tooth tips of a non-engaged rack sweeping past and contacting the outer surface, while the remaining rack is engaged by the pinion means, (b) the cam means has leading and trailing ends with respect to the pinion rotation, the leading end being approached and passed by a particular pinion tooth prior to the trailing end of the cam means, (c) the curved outer surface of the cam means is disposed at a greater radial distance from the pinion axis adjacent the leading end thereof than adjacent the trailing end thereof.