Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B41/00—Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power
  • F02B41/02—Engines with prolonged expansion
  • F02B41/10—Engines with prolonged expansion in exhaust turbines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/004—Engines characterised by provision of pumps driven at least for part of the time by exhaust with exhaust drives arranged in series
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/013—Engines characterised by provision of pumps driven at least for part of the time by exhaust with exhaust-driven pumps arranged in series
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B75/00—Other engines
  • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
  • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
  • F02B2075/027—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle four
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B3/00—Engines characterised by air compression and subsequent fuel addition
  • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• This invention relates to compound power units of the type wherein a turbocharged internal combustion engine has its turbocharger or lowest pressure turbocharger coupled to the output shaft of the engine via a continuously variable transmission (CVT) to supply excess power from the turbocharger to the output shaft.
• CVT continuously variable transmission
• the invention consists in a compound power unit including a reciprocating internal combustion engine, having an output shaft, and at least one turbocharger connected to the engine output shaft through a continuously variable transmission means and means for controlling the continuously variable transmission means to transfer power between the turbocharger and the engine output shaft, in either sense, in dependence on the operating conditions of the unit.
• the control means may be responsive to the engine boost pressure, the engine speed or the output shaft speed or any combination of these.
• the control means may also control a variable valve timing mechanism in order to prevent excessive cylinder pressure.
• the use of the CVT connecting the LP turbocharger to the engine output shaft enables the unit to maintain a high rotational speed, thus ensuring that boost pressure is maintained at a high level over the full engine speed range, and enabling the unit to deliver a high and continuously increasing torque as engine speed is reduced.
• the CVT performs the twofold function of either transmitting excess power from the LP turbocharger to the engine output shaft, or alternatively when there is a power deficit in the LP turbocharger, to transmit power in the reverse direction.
• the scheme offers much greater operational flexibility than either turbocharged or conventional compound schemes with a separate power turbine as a result of the higher and continuously increasing torque level with reducing engine speed. This will result in simplification of the transmission system with fewer gear ratios being required.
• the invention consists in a compound power unit, an internal combustion engine and at least one turbocharger connected to the engine output shaft through a continously variable transmission (CVT) , so that power can be transferred between the engine and the turbocharger in either sense.
• CVT continously variable transmission
• Figure 2 is a torque-speed curve illustrating the performance of such a power plant.
• FIG 3 is a notional control schedule for the LP turbocharger CVT.
• a power plant is generally indicated at 10 in Figure 1 and comprises a reciprocating engine 11, which may be two stroke or four stroke, having an output shaft 12; a gearbox 12a; a turbocharging unit generally indicated at 13; a continuously variable transmission 14 coupled between the turbocharging unit 13 and the shaft 12; and a control unit 15.
• the turbocharging unit 13 receives exhaust from the engine 11 via pipe 16 and this drives a high pressure turbine 17 and then a series connected low pressure turbine 18.
• Each turbine has an associated compressor 19,20 which it drives via a respective shaft 21,22 such that air is drawn through an inlet 23, into the low pressure compressor 19, and then passed through an intercooler 24 to the high pressure compressor 20. This in turn feeds the pressurised air through an after cooler 25 into the engine 11.
• the pressure of the air entering the engine is monitored by a pressure transducer 26.
• the intercooler 24 and after cooler 25 are provided to give greater thermodynamic efficiency and reduced thermal loading.
• a speed transducer 27 is provided to monitor the speed of the output shaft 12 and the output of both this transducer and the pressure transducer 26 are fed to the control unit 15.
• the control unit 15 controls the CVT 14 to transfer power between the low pressure turbine 18 and the output shaft 12 in either sense in ⁇ ependence on the operational conditions indicated by the transducers 26,27 and in accordance, for example, with a control schedule -uch as described below in connection with Figure 3.
• curve A is typical of a 2 stage turbocharged engine giving approximately 25% torque back-up at 60% rated speed.
• TUTESHEET similar fraction of rated speed.
• the compound engine with CVT drive to the low pressure turbocharger and which is the subject of this Application has a greatly improved torque curve, C, with approximately 50% torque back-up achieved at minimum governed engine speed rather than at some intermediate speed level between minimum and rated speed.
• Figure 3 shows a notional control schedule for the CVT and valve mechanism, the former showing the progressive decease in CVT speed ratio defined as output speed to engine crankshaft sprocket input speed from turbocharger sprocket with reduction in engine speed, and also as a function of load.
• the control schedule for the valve mechanism in this case for a four stroke engine, shows the progressive advance in inlet valve closing as a function of reducing engine speed only.
• variable valve timing mechanism 29 may be provided under the control of the control unit 15. This variable inlet closing prevents the build up of excessive cylinder pressure at high boost pressures.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Supercharger (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10679734

Family Applications (1)

Country Status (4)

Cited By (1)

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Family Cites Families (4)

• 1990
  • 1990-07-27 GB GB909016480A patent/GB9016480D0/en active Pending
• 1991
  • 1991-07-18 WO PCT/GB1991/001208 patent/WO1992002719A1/en not_active Application Discontinuation
  • 1991-07-18 EP EP91913588A patent/EP0541613A1/de not_active Withdrawn
  • 1991-07-18 JP JP91512366A patent/JPH05508695A/ja active Pending

Non-Patent Citations (1)

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