Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/06—Control using electricity
  • F04B49/065—Control using electricity and making use of computers

Definitions

• This invention relates to a fluid- working machine.
• the time-averaged flow of fluid is variable in all four quadrants of motion.
• the invention is applicable to any machine with working chambers, which alternately expand and contract, whether by pistons and cylinders, vanes, lobes or gears and where the primary method of commutating fluid to the working chambers is by a rotating port plate, synchronised to the phase of the chamber expansion and contraction cycle, which alternately connects high and then low pressure fluid manifolds to each working chamber.
• the invention provides a fluid-working machine according to claim 1.
• a valve into the fluid connection between the commutating means and each of the working chambers allows each working chamber to be isolated from the commutating means. Chambers which are isolated in this way by the valve operate in an idle condition, whereby no useful fluid work is done by the chamber, and thus the displacement per revolution of the machine is reduced.
• such valves may be controlled mechanically, allowing the machine to be used in a reduced displacement mode when it is desired, for instance, to operate at high speed.
• Such mechanical control may be automatic, for instance reducing the displacement of the machine as the speed of rotation increases above a threshold.
• valves are individually controlled by an electronic signal, allowing each of the chambers to be isolated according to the command of an electronic controller.
• an electronic controller has an input signal of the position of the shaft of the machine, allowing the timing of the valve actuation to be phased relative to the position of the shaft, allowing each chamber to be isolated from the commutator on a stroke-by-stroke basis.
• the drawing shows a machine comprising a working chamber 4 in the form of cylinder containing a piston actuating a crankshaft 5.
• a conventional commutator plate 2 alternately connects the chamber 4 to port A or, via a toroidal cavity 10, to port B, one of the ports being a high-pressure port and the other a low-pressure port.
• the machine operates as a motor with fluid being supplied at high pressure at port A and exhausted at low pressure at port B, but both the pressures and the direction of flow could be reversed separately without changing the apparatus shown.
• valve 1 When the valve 1 is left in the open position the working chamber functions, as normal, to produce a working cycle.
• the time averaged flow is varied by deciding on a chamber-by-chamber basis whether to effect idle or working cycles. The decisions are taken as each successive chamber nears the minimum volume condition, irrespective of whether the machine is working as a pump or a motor.
• An electronic controller 6 senses the phase of the working chamber cycle using a once-per-revolution shaft sensor 7, an encoder, a resolver or some similar means. At times coinciding with the minimum working chamber volume the controller can either leave the on-off valve in its de- energised open state or pull it closed through electromagnetic means.
• the controller reads the system demand, either through an analogue or digital input line or a bus 8, and decides whether the working chamber reaching the minimum volume condition should be left working or idled by closing the valve 1.
• the on-off valve 1 defaults to the open position and is pulsed to close, but it is possible to see that the opposite operating mode, i.e. default closed, pulse to open would also have application where a power-off freewheel characteristic was required.
• the controller decisions can also be made entirely on the basis of shaft speed in order to limit the rate of increase of shaft power.
• the electronic controller would require no external demand signal and would make the sequential on-off valve actuation decisions on the basis of a pre-programmed flow versus speed function.
• the decision sequence can be determined in order to limit individual wheel slip, to create a skid steering effect or to create graded changes in torque and thus controlled vehicle accelerations.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fluid-Pressure Circuits (AREA)
• Hydraulic Motors (AREA)
• Reciprocating Pumps (AREA)
• Details Of Reciprocating Pumps (AREA)
• Control Of Positive-Displacement Pumps (AREA)
• Lifting Devices For Agricultural Implements (AREA)
• Servomotors (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=32247599

Family Applications (1)

Country Status (8)

Cited By (13)

Families Citing this family (9)

Citations (5)

Family Cites Families (10)

• 2004
  • 2004-03-31 GB GBGB0407297.1A patent/GB0407297D0/en not_active Ceased
• 2005
  • 2005-03-31 DE DE602005021087T patent/DE602005021087D1/de not_active Expired - Lifetime
  • 2005-03-31 US US10/599,475 patent/US20070258832A1/en not_active Abandoned
  • 2005-03-31 JP JP2007505631A patent/JP2007530865A/ja active Pending
  • 2005-03-31 AT AT05729670T patent/ATE467049T1/de not_active IP Right Cessation
  • 2005-03-31 WO PCT/GB2005/001235 patent/WO2005095800A1/en not_active Ceased
  • 2005-03-31 CN CN200580014182A patent/CN100587269C/zh not_active Expired - Fee Related
  • 2005-03-31 EP EP05729670A patent/EP1738077B1/en not_active Expired - Lifetime

Patent Citations (5)

Non-Patent Citations (1)

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