Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid pump and motor in one of plural paths to or from...
Patent
1995-10-11
1997-07-01
Ta, Khoi Q.
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid pump and motor in one of plural paths to or from...
475 76, 475 80, 475207, 475214, F16H 3708
Patent
active
056431210
DESCRIPTION:
BRIEF SUMMARY
This invention relates to continuously-variable-ratio transmissions ("CVT's") including, as basic components, a ratio-varying member ("variator"), a gearing unit capable of splitting and recirculating power, and a plurality of clutches alternatively engageable to connect the combined output of the variator and unit by way of further gearing to a final output shaft of the CVT as a whole. In any single typical "regime" of the CVT, that is to say when a particular one of the clutches is engaged, the ratio range of the CVT is a function of that of the variator. Providing more than one alternative clutch/further gearing combination to transmit the drive to the CVT output creates a "multi-regime" system in which the full variator range may be utilised in each of the regimes, so that the ratio range of the CVT as a whole is extended, and can approximate to the ratio range of the CVT, raised to the power of the number of regimes. While the invention includes transmissions with variators that are capable of delivering zero output speed in response to finite input speed, the invention particularly applies to CVT's whose variators are of belt-and-sheave or other type that are not capable of delivering zero output speed. More particularly still, the invention applies to CVT's with variators of the toroidal-race, rolling-traction type.
The invention arises particularly from a consideration of the needs of a vehicle such as a front-loading dumper truck. A CVT for such a vehicle requires not only a wide total range, typically giving the vehicle a maximum reverse speed with a value that amounts to a substantial fraction--say 60%--of the maximum forward speed. Two further desiderata are, firstly, the CVT should be capable of delivering high torque when the vehicle is moving at low speeds, both forwards and in reverse, when the vehicle will typically be advancing a bucket into a mass of earth, sand, stones or the like, filling it and then reversing to withdraw it. Secondly, where the transmission is a multi-regime CVT it is particularly advantageous that the range of one of the several regimes should include both forwards and reverse motion, with a "geared neutral" condition between them, to ease the driver's task in changing frequently between forward and reverse motion when manoeuvring the vehicle at low speed, and to avoid the need for forward and reverse clutches which would otherwise need to be changed-over frequently in that driving condition when the CVT is required to deliver particularly high torque.
It should also be noted that the CVT of the present invention is to be distinguished particularly from the CVT's described in prior Patent Publication EP-A-0302188, which describes CVT's in which the capacity to operate in a succession of regimes, and so provide an extended overall ratio range, derives from connecting the CVT output alternatively to one of two shafts whose speeds increase and decrease reciprocally. In EP-A-0302188, however the gearing units comprise two epicyclic gears so arranged that both of them both split and recirculate power in all regimes. Later gears must therefore be designed to withstand continuous and prolonged usage. The gearing units of the present invention again contain two such gears, but arranged so that only one of them ever recirculates power, and does so in one regime only.
The invention is defined by the claims, the contents of which are to be considered as included within the disclosure of this specification. The invention includes CVT's as described with reference to the accompany drawings, will now be described by way of example with reference to those drawings in which:
FIG. 1 is a diagrammatic view of one CVT, taken in a common plane including the axes of the variator, the epicyclic unit and the final drive shaft;
FIG. 2 is a schematic view of parts of the CVT of FIG. 1, including further ratio and speed values;
FIG. 3 is a table of speed and ratio values;
FIGS. 4-6 are similar to FIGS. 1-3 but relate to an alternative CVT, and
FIG. 7 shows a modification of FIG. 1 in outline
REFERENCES:
patent: 5030178 (1991-07-01), Ming-Luen
patent: 5055094 (1991-10-01), Cataldo
patent: 5207736 (1993-05-01), Fredriksen
patent: 5403241 (1995-04-01), Jarchow et al.
patent: 5496223 (1996-03-01), Jarchow
Fellows Thomas George
Greenwood Christopher John
Ta Khoi Q.
Torotrak (Development) Limited
LandOfFree
Continuously-variable-ratio transmissions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuously-variable-ratio transmissions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuously-variable-ratio transmissions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-591746