William RAMPEN / Niall CALDWELL, et al.
Artemis Digital Hydraulic Pump
Artemis Intelligent Power Ltd
Unit 3 Edgefield Industrial Estate
Loanhead
Midlothian EH20 9TB
Tel : +44 131 516 8606
Fax : +44 131 440 0005
web : http://www.artemisip.com
Artemis Digital Displacement® technology replaces the port plates and swash plates in conventional hydraulic machines with computer controlled high speed solenoid valves. This enables very high operating efficiency in part-load conditions, and unprecedented controllability, especially in multi-service and synchronized applications.
http://www.artemisip.com/appli_auto_transm.htm
Automobile Transmission
Artemis's Digital Displacement® technology is ideal for building series or parallel hydraulic hybrid transmissions for automotive applications. Artemis has recently successfully tested a BMW 530i equipped with such a Digital Displacement® Hybrid transmission. Details of the programme: : http://www.artemisip.com/Heddat2.htm
Emissions reduction
Independent tests have confirmed that a prototype car, fitted on a BMW 530i, gave double the MPG in city driving compared to the same car with a six speed manual transmission. Overall, including highway driving, the prototype had 30% lower carbon dioxide emissions than it had before the company fitted its energy saving transmission.
System design
A Digital Displacement® Hybrid Transmission consists of connecting a Digital Displacement® Pump mounted to a standard internal combustion engine. The pump is hydraulically connected to Digital Displacement® Motors coupled to the wheels.
Chassis Systems
A DD Pump/Motor can control multiple single-acting rams at high bandwidth and with high efficiency without proportional valves, enabling its use in vehicle active suspension systems. The ability to go from idle to full flow in under 30ms allows rapid position and stiffness changes even in high performance vehicles. And because it is directly microprocessor controlled, a DD machine is easily integrated into a drive-by-wire control architecture.
http://www.artemisip.com/heddatoperation.htm
Artemis Digital Displacement® technology replaces the port plates and swash plates in conventional hydraulic machines with computer controlled high speed solenoid valves.
The core component of a Digital Displacement® system is a hydraulic piston pump/motor with actively controlled poppet valves which rectify the flow into, and out of, each cylinder. The cylinders are generally disposed radially around an eccentric with valving around the periphery. Banks of cylinders can be assembled along a common crankshaft to allow multiple independent outputs. The valves are each operated by a small electro-magnetic latch so that they can be opened and closed on a stroke-by-stroke basis. The solenoid coil in each latch is activated by a power FET, which is in turn connected directly to the digital output of an embedded controller.
Each cylinder has two actively controlled poppet valves, one to each of the high and low pressure manifolds. When idling (left in the diagram below) the fluid flows in and out around the low pressure valve. The high pressure valve remains closed and isolates the reciprocating cylinder from the high pressure fluid. When pumping (right), the microprocessor closes the low pressure valve to send fluid to the high pressure service.
Artemis Digital Displacement® technology replaces the port plates and swash plates in conventional hydraulic machines with computer controlled high speed solenoid valves.
The core component of a Digital Displacement® system is a hydraulic piston pump/motor with actively controlled poppet valves which rectify the flow into, and out of, each cylinder. The cylinders are generally disposed radially around an eccentric with valving around the periphery. Banks of cylinders can be assembled along a common crankshaft to allow multiple independent outputs. The valves are each operated by a small electro-magnetic latch so that they can be opened and closed on a stroke-by-stroke basis. The solenoid coil in each latch is activated by a power FET, which is in turn connected directly to the digital output of an embedded controller.
6 cylinder Digital Displacement™ Pump / Motor in pumping sequences -- Each cylinder has two actively controlled poppet valves, one to each of the high and low pressure manifolds. When idling (left in the diagram below) the fluid flows in and out around the low pressure valve. The high pressure valve remains closed and isolates the reciprocating cylinder from the high pressure fluid. When pumping (right), the microprocessor closes the low pressure valve to send fluid to the high pressure service.
It is also possible to hold the high pressure valve open, taking fluid from the high pressure output.
The net result of the rapid sequenced valve actuation is that, at the end of each stroke, each cylinder can be reconfigured to either pump, motor or idle. By controlling the sequence of cylinder enablings, the machine can pump fluid to a hydraulic service or accept it back (while the returning fluid actually helps to drive the crankshaft of the machine) at infinitely variable flow-rates. The valve actuation decisions are occurring every four or five milliseconds in a typical multi-cylinder pump driven at industrial diesel speeds, which gives an effective frequency response greater than 20 Hz.
http://www.artemisip.com/heddatbenefits.htm
Advantages
Unparalleled Efficiency -- DD machines are well over 90% efficient, even at part load and high pressures. There are outstanding efficiency gains at the system level too due to its completely independent outputs and ability to efficiently reclaim energy from high pressure services and route it to other services.
Unsurpassed Performance -- Digital Displacement® (DD) uses high speed poppet valves controlled by power electronics. DD machines have a bandwidth of around 20Hz and can produce full output flow in around 25ms.
Unbeatable Controllability --DD machines have a modular construction that allows a multiplicity of independent services to be supplied by a single compact machine without recourse to either flow divider valves or priority systems.
DD technology is surprisingly low cost, due to its modular construction and relaxed component tolerances compared to other variable flow machines. System costs are also typically much lower than possible using conventional hydraulics...
DD machines inherit the extreme ruggedness of other poppet machines and the ability to operate on low lubricity fluids such as biodegradable emulsions, water and fuel... A very high power density, three to ten times higher than electrical machines... A potential power range from 1 kilowatt to over 10 megawatts... Reliable load holding due to seating valves. There is absolutely no leakage at zero flow.
http://www.artemisip.com/appli_renewable.htm
Wind Turbines
The majority of large modern wind-turbines use mechanical gearboxes to couple the slow rotation of the blades to the high-speed of the generator. However gearboxes are heavy and prone to failure. In-situ replacement is very expensive. Other wind-turbine designs use low-speed electrical-generators that are directly coupled to the shaft of the wind-rotor. Though reliable these machines are costly, very heavy and need full-power electronic frequency and voltage converters to condition their power for supply to the electrical network.
Digital Displacement® is in development at scales appropriate for a 2MW renewable energy device.
High-pressure oil-hydraulic transmissions have long been considered for wind-turbines but the part-load efficiencies of the available hydraulic pumps and motors have been too poor to make them attractive. Artemis believes that the prototype Digital Displacement® wind-turbine transmission that it is now building will radically change this perspective. The new transmission will be lighter than competing technologies and will have unprecedented levels of controllability and electrical power quaility. It will be suitable for retro-fit to existing machines and also for use in the next generations of very-large turbines.
A continuously variable transmission-ratio allows the rotor to be operated at the best speed for optimal power capture whilst the synchronous generator is driven at a much higher constant speed. The hydraulic transmission shares its load across many pumping-modules and so avoids the few highly stressed line-contacts that are inherent in gear boxes. The ability of hydraulics to limit pressure to a safe working value avoids potential over-stressing of the driveline. Short-term storage in accumulators can smooth out wind turbulence.
http://www.artemisip.com/appli_mobile_hyd.htm
Mobile Hydraulics
Mobile hydraulics applications highlight the following unique features of DD technology:
Unprecedented efficiency, especially at part load -- Simply replacing existing load-sensing open circuit pumps with DDPs will lead to energy savings of at least 30% over typical offroad vehicle duty cycles. But in systems designed to take advantage of the unique properties of DDPs the savings can much greater. Studies on replacing conventional proportional valves and load-sensing axial pumps with Direct Displacement Control of loads show energy savings of up to 60%. This allows a massive reduction in or, possibly, elimination of cooling radiators.
Multiple independent services -- Banks of Digital Displacement® Pumps (DDP) can stacked on a common shaft, and split into independently controllable services. This allows a single pump to supply propel, auxillaries, and dedicated work function services, all running at different flows and pressures, commanded by CANBUS.
Direct control of rams and motors without proportional valves -- DDPs can change from idle to full flow and vice-versa in under 30ms. This high pump bandwidth means that in many applications proportional valves can be eliminated and the load can be controlled directly from a DDP service.
Precise, linear flow control with no hysteresis -- Digital Displacement® pumps allow open loop position control of hydraulic actuators without the need for feedback sensors. DD adds robotic motion control to mobile hydraulics without a complicated and expensive feedback system.
Mechanically simple, manufacturable design -- Modular, scalable construction reduces parts inventory allows mass customisation. Digital Displacement® Pumps put the the control functions into the software, not the hardware. Features such as programmable s-curve motions, pressure control loops, anti-stall and power limiting can all be incorporated in software.
William RAMPEN, Niall CALDWELL, et al. : Artemis Patents
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2008012587&F=0
A DIGITAL HYDRAULIC PUMP/MOTOR TORQUE MODULATION SYSTEM AND APPARATUS
WO2008012587
2008-01-31
Abstract -- The present invention provides a hydraulic pump
(10) for use in driving a load (54) with a control modulation system (9)
which modulates a primary control signal in order to accommodate variations
in secondary changeable parameters which require control at a higher frequency
or have a lower latency.
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2008012586&F=0
A COOLING SYSTEM AND A TRANSMISSION SYSTEM HAVING SAID COOLING SYSTEM
INTEGRATED THEREWITH
WO2008012586
2008-01-31
Abstract -- The present invention provides a cooling system
(10) such as employed in cooling a heat source (12) and a transmission
system having said cooling system (10) integrated 5 therewith. The cooling
system further includes a pump (36) for supplying hydraulic fluid under
pressure to a motor (20) for driving a fan (18) employed in the cooling
process. In operation, a controller initiates operation of the pump (36)
such as to supply hydraulic fluid to said motor (20) only when needed,
thereby to improve the efficiency and controllability of the cooling system.
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2008009950&F=0
FLUID POWER DISTRIBUTION AND CONTROL SYSTEM
WO2008009950
2008-01-24
Abstract -- A fluid power system comprises a pump with multiple
independently variable outlets (11, 12, 13, 14), each of which is capable
of delivering fluid in individually controllable volume units and a plurality
of hydraulic loads (15, 16, 18, 20). A system of switching valves is configured
to create fluid connections between the pump outlets and the loads. A control
system commands both the pump and the switching valves, so as to create
valve state combinations to satisfy load conditions as demanded by an operator.
The number of pump outlets (11, 12, 13, 14) connected to one or more of
the loads (15, 16, 18, 20) is changeable to satisfy the flow required of
the load due to the operator demand, each pump outlet being commanded to
produce a flow depending on the status of other outlets connected a load
to which the outlet is connected and the operator demand for that load.
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2007088380&F=0
OPERATING METHOD FOR A HYDRAULIC MACHINE
WO2007088380
2007-08-09
Abstract -- A hydraulic machine has at least one working chamber
(11) of cyclically changing volume, and low- and high-pressure valve means
(15, 13) to control the connection of the or each chamber to low- and high-pressure
lines (16, 14) respectively. A method of operating the machine includes
holding the low-pressure valve means (15) closed during at least an entire
cycle of the chamber (11), starting at minimum chamber volume, such that
gas dissolved in liquid in the chamber is released therefrom during an
expansion of the chamber volume and re-dissolved during a reduction thereof.