Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission...
Reexamination Certificate
2003-02-13
2004-12-28
Pang, Roger (Department: 3681)
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
C074S125500
Reexamination Certificate
active
06835153
ABSTRACT:
FIELD OF THE INVENTION
This invention relate to a stepless infinitely variable transmission (IVT) machine which is capable of producing an output angular velocity which is continuously variable over a predetermined range of angular velocities relative to the input angular velocity.
BACKGROUND TO THE INVENTION
Many IVT machines have over the years been proposed and developed in attempts to produce, from a constant input angular velocity, an acceptable linear continuously variable output angular velocity and torque.
The basic approach to these machines has been initially to apply a single input angular velocity to a number of parallel stages of the machines which by means of cams, slotted plates, linkages, off-centred sun gears, non-circular gears, orbital devices and so on produce pulsed or cycled angular velocities (angular acceleration and deceleration cycles) which are appropriately phased to the input angular velocity. The pulsed or cycled angular velocities from the machine input stages are then used to drive selective extraction devices, such as overrunning or sprag clutches and/or differentials which extract the maximum portions of the driven cycles of the parallel stages to provide modulated angular velocity outputs. These outputs are then recombined in an output stage of the machine to provide the output angular velocity of the machine. Examples of the these machines are disclosed in the specifications of the following publications: WO 82/02233, WO 89/11604, WO 90/01648, WO 91/18225 and WO 94/11652.
Common problems which are typically associated with IVT machines of the prior art are that:
they are capable of transmitting power in only one direction of rotation, which cannot be reversed,
their cyclic angular velocity generating devices generate, in each parallel stage of the machine, a full cycle of a periodic motion on each revolution of their input shafts with their single drive direction overrunning clutch extraction devices being capable of clipping only the single maximum velocity peak from each cycle. The consequence of this is that the angular velocity output arrangements of the machines, such as planetary gear systems, are largely incapable of fully modulating the coarsely rippled output of the extraction devices to an acceptable purely or nearly so theoretically constant linear output velocity, and
the majority of the cyclic angular velocity generating devices which are employed in the IVT machines and which include oscillating components such as the slotted plates, linkages which drive or are driven by off-centre gears, cams and the like suffer from balancing and other vibration problems which are principally caused mainly by shock loads generated by the direction changing mechanisms.
SUMMARY OF THE INVENTION
A method of operating an IVT machine according to the invention includes the steps of rotating an angular velocity input member of the machine at a constant angular velocity applying the input angular velocity in a fixed ratio to two parallel stages of the machine which each include a plurality of cyclic angular velocity generating devices which in each stage are rotated in a common direction, generating a cyclic angular velocity by means of each cyclic angular velocity generating device to produce the same number of angular velocity output cycles from each stage for each revolution of the angular velocity input member with the cyclic angular velocity output of each stage being evenly phased relatively to the other, inverting the cyclic angular velocity outputs of at least one stage relatively to the other, adjusting the amplitudes of the cyclic output angular velocity outputs of the cyclic angular velocity devices in at least one of the stages [
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,
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] to correspond in amplitude and shape to those of the other stage as the angular velocity ratio of the machine is changed, applying each of the cyclic angular velocities of the cyclic angular velocity generating devices in each stage to an extraction device causing each of the extraction devices to extract the absolute global maximum or minimum angular velocity peak pulses from each of the cyclic angular velocities, summing and combining the pulsed outputs from each stage applying the relatively inverted combined individual pulsed outputs from each stage individually to a planetary gear arrangement cancelling the inverted, equal amplitude, evenly phased pulsed outputs from each stage in the planetary gear arrangement and applying a single non pulsing output angular velocity from the planetary gear arrangement to an output member of the machine.
The cyclic angular velocity generating devices may each include at least two shafts which are coupled by at least one universal joint and the method includes the steps of adjusting the amplitude of the cyclic angular velocity of each cyclic angular velocity generating device by moving one of the shafts relatively to the other to vary their angular dispositions relatively to each other.
An infinitely variable transmission according to the invention comprises an angular velocity input member, an angular velocity output member, two parallel stages of cyclic angular velocity generating devices, a drive arrangement for applying angular velocity from the input member to each of the angular velocity generating devices, extraction devices which are each driven by a cyclic angular velocity generating device in each of the two stages which extracts the absolute maximum angular velocity pulsations from the cyclic angular velocity output of the cyclic angular velocity generating device which drives it, means for varying the amplitude of the cyclic angular velocity produced by at least one of the stages, an arrangement for summing and combining the pulsating angular velocity outputs from the extraction devices and applying a single non-pulsating output angular velocity to the output member, characterised in that each of the cyclic angular velocity generating devices includes two shafts which are coupled to each other by at least one universal joint, the drive means includes a drive arrangement for driving each of the angular velocity generating devices in a first of the stages in a first direction of rotation and each of the angular velocity devices of the second stage in an opposite direction and in a fixed ratio of rotation relatively to the angular velocity generating devices of the first stage so that each stage produces the same number of angular velocity cycles per revolution of the input member and the amplitude varying means is an arrangement for angularly moving one of the shafts of each of the cyclic angular velocity generating devices relatively to the other in at least one stage to enable the amplitudes of the cyclic angular velocities generated by the cyclic angular velocity generating devices in that stage to be varied to correspond to the angular velocity amplitudes in the remaining stage.
The angular velocity generating stage may include at least three cyclic angular velocity generating devices and the angular velocity generating stage two cyclic angular velocity generating devices. Conveniently, the angular velocity generating devices in each stage are rotationally phased 60° apart with reference to the input member.
The universal joint sets of the stage
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may be rotated by the drive means in a ratio of 1:1 relatively to and in the same direction of rotation as the input member and the universal joint sets of the stage are rotated in a ratio of 1:1.5 relatively to and in a direction opposite to the direction of rotation of the input member.
In a preferred form of the invention the angular velocity generating devices are each a universal joint set which includes a universal shaft which carries at each of its ends a universal joint with one of the universal joints being driven by the drive means with the other connected by a shaft to an extraction device. Preferably, the universal shaft of each universal joint set is telescopically variable in length. The yokes of the universal joints of the universal joint sets which are attached to the universal
Pang Roger
Varibox (PTY) Limited
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