This invention relates to a machine capable of sustained delivery of mechanical energy with intermittent energy input. The invention also relates to a method of operation of such a machine.
The machine operates as an engine for delivery of mechanical work for an extended duration in comparison to the duration of energy input into the engine.
With a typical engine, input energy is delivered to the engine in a substantially constant manner for conversion into output energy (in the form of mechanical work). By way of example, in the operation of an electric motor, input electrical energy is delivered continuously to the motor for conversion into output energy in the form of mechanical work.
There are circumstances where it is desirable to have an engine which can provide a sustained energy output with only intermittent energy input. One such circumstance is where an engine is required to drive an electrodynamic machine for producing electrical power at a location where a reticulated power supply is unavailable. Some of the electrical power so produced can be utilised to operate the source providing the intermittent input energy.
The present invention provides a machine comprising:
a drive shaft;
a first gear train and a second gear train both drivingly connected to the drive shaft;
the first gear train having a first input shaft;
the second gear train having a second input shaft;
a first drive mechanism drivingly connected to the first input shaft;
a second drive mechanism drivingly connected to the second input shaft; and
a power means for operating the first and second drive mechanisms to sequentially move through power and return strokes whereby upon each power stroke the drive mechanisms respectively apply torque to the first and second input shafts.
Preferably, the sequence in which torque is applied to the first and second input shafts is such that torque is initially delivered to both the first and second input shafts and subsequently to only one of the input shafts. This is achieved by one drive mechanism completing its power stroke after completion of the power stroke by the other drive mechanism. Conveniently, said one drive mechanism has completed about one-half of its power stroke at the stage where the other completes its power stroke.
The transmission ratio between the first drive mechanism and the drive shaft, and the transmission ratio between the second drive mechanism and the drive shaft, can each be selected according to the particular application of the engine.
The first and second gear trains may share some common gears.
In one arrangement, the first drive mechanism may comprise a first rack and pinion mechanism. With this arrangement, the pinion of the first rack and pinion mechanism is drivingly connected to the first input shaft.
Further, the second drive mechanism may comprise a second rack and pinion mechanism. With this arrangement, the pinion of the second rack and pinion mechanism is drivingly connected to the second input shaft.
The power means may comprise a spring structure associated with each rack and loading means for loading the spring structure to generate a spring force therein, wherein the spring force is utilised to drive the rack in one direction to provide the power stroke for effecting rotation of the respective pinion.
Preferably, the pinions are adapted to freewheel with respect to their respective input shafts upon movement of the racks in the reverse direction (being the return stroke). The freewheeling action of each pinion with respect to its input shaft may be provided by a clutch mechanism operating between the pinion and the input shaft.
The first and second racks preferably undergo their return strokes in unison.
The spring structure may be of the type which is loaded in tension or of the type which is loaded in compression.
The spring structure may be in any appropriate form, such as, for example, a mechanical spring, a pneumatic spring, a body of elastic material such as rubber, or any combination thereof. Where a mechanical spring is utilised, it can be of any suitable type, such as a helical spring or a coil spring.
The loading means for loading the spring structure may comprise a power mechanism including a telescopic ram, whereby operation of the ram effects rapid loading of the spring structure. Conveniently, the ram comprises a hydraulic ram. The hydraulic ram is preferably included in a hydraulic circuit which further includes a hydraulic pump driven by an electric motor. The electric motor may be powered from an electrical supply generated by an electrodynamic machine driven by the engine.
The machine may further comprise
a third gear train and a fourth gear train both drivingly connected to the drive shaft;
the third gear train having a third input shaft;
the fourth gear train having a fourth input shaft;
a third drive mechanism drivingly connected to the third input shaft;
a fourth drive mechanism drivingly connected to the fourth input shaft,
wherein the power means drives the third and fourth drive mechanisms to sequentially move the third and fourth through power and return strokes whereby upon each power stroke the third and fourth drive mechanisms apply torque to the third and fourth input shafts.
The various drive mechanisms are preferably arranged to operate in a pre-determined sequence.
Preferably, the pre-determined sequence is such that torque is initially delivered to both the first and second input shafts and subsequently to only first input shaft during which stage torque is initially delivered to both the third and fourth input shafts and subsequently to only the third input shaft during which stage torque is initially delivered to both the first and second input shafts and subsequently to only the first input shaft.
The third and fourth gear trains may share some common gears with each other and may also share some common gears with the first and second gear trains.
In an alternative arrangement, each drive mechanism may comprise a gear and pinion mechanism.
With such an arrangement, the power means may comprise a spring structure associated with each gear and a loading means for loading the spring structure to generate a spring force therein.
The spring structure may comprise at least one, and preferably two or more, axial springs (such as extension springs or compression springs) each having one end attached to the respective gear and the other end fixed, whereby rotation of the gear in one direction corresponds to extension of the spring and rotation of the gear in the other direction corresponds to contraction of the spring.
Conveniently, each spring is an extension spring in which case rotation of the gear in one direction causes extension of the spring to effect loading thereof such that the spring force so generated subsequently effects reverse rotation of the gear upon contraction of the spring.
With such an arrangement, the drive mechanism performs a loading (return) stroke upon rotation of the gear in the direction corresponding to loading of the spring and a power stroke when moving in the reverse direction under the influence of the spring.
The loading means may be common to both the first and second drive mechanisms.
The loading means may comprise a movable element operably connected to the gears of the two gear and pinion mechanisms whereby linear movement of the movable element in one direction causes rotation of the gears and thus loading of the respective springs connected thereto.
The movable element may provide a cam having an arcuate cam profile, and each gear may have a crank element engagable with the cam profile for movement therealong upon linear movement of the movable element in said one direction.
The movable element may comprise an arcuate rail which in effect provides the cam for driving the cranks of the two gears. The arcuate rail may be of channel cross-section and each crank may incorporate a roller received in the channel for rolling movement therealong.
The loading means may further comprise a power mechanism for effecting linear movement of the movable element in said one direction. The power mechanism may comprise a telescopic ram such as a hydraulic ram.
Conveniently, the movable element can undergo reverse movement under the influence of at least one of the gears as the latter rotates to perform its power stroke.
The first drive mechanism is drivingly connected to the drive shaft by way of a first gear train, and the second drive mechanism is drivingly connected to the drive shaft by way of a second gear train. The first and second gear trains may share some common gears.
The pinion of each gear and pinion mechanism is adapted to freewheel as its respective gear undergoes a loading (return) stroke.
The transmission ratio between the first drive mechanism and the drive shaft, and the transmission ratio between the second drive mechanism and the drive shaft, can each be selected according to the particular application of the engine. However, the arrangement is such that the two drive mechanisms perform their loading (return) strokes in unison under the influence of the common power means, and perform their respective power strokes at different rates, with one drive mechanism completing its power stroke after completion of the power stroke of the other drive mechanism.
The present invention also provides a machine comprising:
a drive shaft;
a first gear train and a second gear train both drivingly connected to the drive shaft;
the first gear train having a first input shaft;
the second gear train having a second input shaft;
a first drive mechanism drivingly connected to the first input shaft;
a second drive mechanism drivingly connected to the second input shaft;
each drive mechanism comprising a gear and pinion mechanism;
a power means for operating the first and second drive mechanisms to sequentially move through power and return strokes whereby upon each power stroke the drive mechanisms respectively apply torque to the first and second input shafts; and
the power means comprising a spring structure associated with the gear of each gear and pinion mechanism, and a loading means common to both drive mechanisms for loading the spring structures to generate spring forces therein.
The present invention also provides a machine comprising a drive shaft, and first, second, third and fourth drive mechanisms drivingly connected to the drive shaft for applying rotational torque thereto during power strokes of the drive mechanisms, the drive mechanisms being operable to perform their respective power strokes in a cycle whereby the first and second drive mechanisms operate together during part of their power strokes and thereafter the second drive mechanism completes its power stroke while the first drive mechanism continues its power stroke during which stage the third and fourth drive mechanisms operate together during part of their power strokes and thereafter the fourth drive mechanism completes its power stroke while the third drive mechanism continues its power stroke during which stage the first and second drive mechanisms operate together during part of their power strokes to repeat the cycle.
The invention also provides a method of operating a machine having a drive shaft, and first and second drive mechanisms operatively connected to the drive shaft for applying rotational torque thereto during power strokes of the drive mechanism, the method comprising the steps of operating the machine in an operating cycle in which both drive mechanisms operate together during part of their power strokes and thereafter one drive mechanism completes its power stroke while the other drive mechanism continues its power stroke, and following completion of the power stroke of said other drive mechanism both drive mechanisms operate together during part of their power strokes to repeat the cycle.
The invention also provides a method of operating a machine having a drive shaft, and first, second, third and fourth drive mechanisms operatively connected to the drive shaft for applying rotational torque thereto during power strokes of the drive mechanisms, the method comprising the steps of operating the machine in an operating cycle in which the first and second drive mechanisms operate together during part of their power strokes and thereafter the second drive mechanism completes its power stroke while the first drive mechanism continues its power stroke during which stage the third and fourth drive mechanisms operate together during part of their power strokes and thereafter the fourth drive mechanism completes its power stroke while the third drive mechanism continues its power stroke during which stage the first and second drive mechanisms operate together during part of their power strokes to repeat the cycle.