Variable speed vehicle powertrains

Details Variable speed vehicle powertrains Variable speed vehicle powertrains

2001-01-04

2004-08-10

Marmor, Charles A. (Department: 3681)

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...

C475S078000, C475S080000

Reexamination Certificate

active

06773368

ABSTRACT:

FIELD OF INVENTION
This invention relates to vehicle powertrains.
BACKGROUND ART
Vehicle powertrains generally are comprised of a power source connected via a clutch mechanism to a geared transmission controlled manually or by a series of clutches and brakes both of which provide generally three or more distinct drive ratios. Most vehicles still use an internal combustion engine as a power source. Internal combustion engines generally have a narrow band of operating revolutions per minute (r.p.m.) matched to the torque or driving force as a “sweet spot” giving maximum fuel is efficiency and minimum pollution.
The effect of the stepped transmission is that in each of the gears or steps the engine is at first subject to high torque demand at low revolutions causing lugging where the piston is moving slower than the flame front in the combustion stroke. As the engine r.p.m. increases, it passes through the sweet spot of balanced operation of r.p.m. and torque with the piston moving at the speed of the flame front and expanding air. The engine r.p.m. then exceeds the balance of r.p.m. and torque requirement and enters an over-speed situation until the next gear is engaged and the foregoing is again repeated through the next and subsequent gear shifts.
On the open highway, more efficiency is obtained by having an overdrive gear that once again more closely balances the engine r.p.m. and torque requirement. This is usually a fixed gear ratio and generally near the maximum capacity of the engine for operating on flat or moderately undulating terrain. When an incline is encountered most automatic transmissions require the driver to operate a manual button or automatically kick down to a lower geared ratio in a relatively large step with resultant inefficiencies. If the load encountered is in the mid top gear/overdrive range, the transmission will often repeatedly change up and down at regular relatively rapid cycles with a resultant acceleration and deceleration obvious to both driver and passengers.
In an attempt to run the engine constantly and consistently in the sweet spot of balanced engine r.p.m. with the required torque and piston speed being balanced with the combustion cycle flame front and expanding gases, prior art shows attempts at combining various gear drive systems requiring a variable speed input. Generally friction drive coned pulleys or rollers are used achieving speed variation by sliding the tapered cones relative to each other. The amount of torque being able to be transferred by this means is minimal and the resultant wear has made this option unworkable Vee pulleys and matching expandable V pulleys using a wide “V” belt have had limited success in the low horsepower area.
Variable speed transmissions using hydraulic pumps and motors in prior art are designed so that as the r.p.m. of the output increases the quantity of oil flow also increases causing additional friction loss due to increased flow. In an attempt to minimise this loss, higher pressures and lower flows have been used. This causes very poor low speed torque characteristics The resultant loss of efficiency and performance, with energy loss, heat generation and the need for cooling dissipation through additional circuits and coolers has meant that this form of transmission has not been viable for high speed vehicular application and has only been applied to low speed tractors and mobile machines.
The present applicant's International Patent Application PCT/AU97/00714 discloses a vehicle power transmission and power train capable of being continuously controlled over a predetermined range of operation by means of an outer transmission and an inner differential gear assembly controlled by two rotatable inputs. The inputs from a microprocessor continually monitor all vital inputs and outputs and making continuous real time micro-adjustments to ensure ease and smoothness for driver and passengers, fuel efficiency and pollution reduction. Although a single power source can be used to drive the two inputs, for example through hydraulic drive systems, the International application primarily describes the use of a split engine or two power sources, one power unit continuously running in the sweet spot for maximum fuel and pollution efficiencies, the second power source being used to balance the variable input forces. The disclosure of International Application PCT/AU97/00714 is incorporated herein by cross reference and are hereinafter referred to as “the applicant's previous application”
DISCLOSURE OF THE INVENTION
For volume automotive manufacture and to minimise capital tooling costs, it is advantageous to use existing high volume engine manufacture. It is also desirable to gain the advantage of continuously running an entire singular power source at maximum balanced r.p.m. and torque, constantly in the sweet spot for maximum fuel efficiency and minimal pollution, and to maintain that operation precisely in all spectrums of vehicle driving range.
It is an object of one aspect of this invention to provide a power dividing device to provide two rotating outputs having variable relative speed of rotation from as single rotatable input. It is an object of another aspect of the present invention to provide a vehicle powertrain and a power transmission capable of being continuously controlled over a predetermined range of operation.
In a first aspect this invention provides a power dividing device to provide two rotating outputs having variable relative speed of rotation from a single rotatable input, said device including a first rotational element driven in rotation about a rotational axis and having a first rotational output; a second rotational element rotatable about said rotational axis and having a second rotational output: a first fluid chamber associated with said first rotational element; first regulating means to vary the volume of said first chamber in response to rotation of said first rotational element: a second fluid chamber associated with said second rotational element second regulating means to vary the volume of said second chamber in response to rotation of said second rotational element; commutator means to at least regularly establish a closed fluid flow communication between said first and second chambers during rotation of said first and second rotational elements; the relative timing of variation of the volumes of said first and second chambers determining the speed of rotation of said second rotational element in response to rotation of said first rotational element.
In another aspect this invention provides a power transmission unit including a power dividing device, an outer main transmission and an inner differential gear assembly;
the power dividing device providing two rotating outputs having variable relative speed of rotation, said device including a first rotational element driven in rotation about a rotational axis by a power unit and having a first rotational output; a second rotational element rotatable about said rotational axis and having a second rotational output; a first fluid chamber associated with said first rotational element; first regulating means to vary the volume of said first chamber in response to rotation of said first rotational element: a second fluid chamber associated with said second rotational element; second regulating means to vary the volume of said second chamber in response to rotation of said second rotational element; commutator means to at least regularly establish a closed fluid flow communication between said first and second chambers during rotation of said first and second rotational elements; the relative timing of variation of the volumes of said first and second chambers determining the speed of rotation of said second rotational element in response to rotation of said first rotational element;
the main transmission having two rotatable input means each respectively driven by the first rotational output and the second rotatable output of said power dividing device, the two input means being operably connected to rotatable outp

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