Patent Application
20120180482
The present invention relates to modern automotive vehicles and in particular to systems such as turbocharger systems for improving efficiency and performance.
Conventional turbochargers use engine exhaust power to drive a turbocharger exhaust turbine which powers an air compressor that supplies high pressure combustion air to the engine. For modern automotive vehicles there is a need for higher specific engine power, lower fuel consumption and lower exhaust emissions. These are met with smaller higher speed engines that require high boost achievable over wide engine speed ranges. A specific need for modern high speed engines is a higher engine torque in the low engine speed range to improve vehicle acceleration. This usually results in an excess of the engine exhaust energy at higher engine speeds. To prevent the turbocharger over-speed and over-pressure, this is currently handled by “waste-gating” substantial portions of the engine exhaust flow which represents a waste of fuel. The wasted energy going out the tail pipe in the form of exhaust gas flow is estimated to be on the order of up to 20% in compact engines.
Applicant was granted on Jul. 20, 1999 U.S. Pat. No. 5,924,286 describing a very high speed radial inflow hydraulic turbine incorporated in a basic turbocharger design to produce a hydraulic supercharger system. The hydraulic turbine assists the turbocharger gas turbine for purpose of increasing engine torque and improving vehicle acceleration at low engine speeds. That patent is incorporated by reference herein especially the turbocharger hydraulic assist turbine shown as part 61 in
While the hydraulic turbine improved performance at low speed performance, there still exists a great need for making use of wasted exhaust flow and improvement in engine fuel consumption at high engine speeds.
This invention provides a hybrid hydraulic turbocharger system for internal combustion engines. The turbocharger system includes a hydraulic pump motor in mechanical communication with said engine drive shaft. The hydraulic pump motor functions as a hydraulic pump driven by the drive shaft of the engine at low engine speeds and functions as a hydraulic motor to provide additional torque to said drive shaft high engine speeds. A hybrid turbocharger unit includes an engine exhaust gas turbine driving a compressor, a hydraulic turbine and a second hydraulic pump, all mounted on said turbocharger shaft. The compressor, driven by exhaust gases produced by said engine and by high pressure hydraulic fluid produced by the hydraulic pump motor at high engine speeds, drives air into the internal combustion engine. The turbocharger shaft provides power to drive a high pressure hydraulic pump impeller which in turn provides high pressure hydraulic flow into the hydraulic pump motor producing additional torque to said engine drive shaft at high engine speeds. The hydraulic turbine driven by high pressure hydraulic fluid from said hydraulic pump protion of the pump motor provides additional boost to the turbocharger unit driving additional air into the engine for acceleration at low engine speeds.
Preferred embodiment of this invention utilizes a plastic-metal radial turbine wheels in which the wheels other than blades are jointly anchored within metal containing wheel as described in U.S. Pat. No. 5,924,286.
A first preferred embodiment of the present invention can be described by reference to the figures.
Constant displacement hydraulic pump/motor 81 is passing the hydraulic flow at rate proportional to the engine RPM. With both turbine inlet valve 123 and pump inlet valve 122 closed, the hydraulic bypass valve 125 is fully open bypassing all the hydraulic pump/motor 81 flow via bypass line 128 thus unloading the pump/motor 81. In that mode there is no power inputted or extracted from the turbocharger shaft. Friction losses from inactive 13.5 mm diameter hydraulic turbine blades 11 and 14.5 mm diameter hydraulic pump blades 12 is projected to be minimal because most of the hydraulic fluid is centrifuged out of both wheels.
During the entire engine operation the lubrication pump 105 supplies hydraulic fluid (oil) to turbocharger bearings via line 86 shown on
Hydraulic pump motor 81 is driven by and drives the engine shaft. There are two principal modes of operation of the present invention. One principal mode is operation to provide boost to the turbocharger at low engine speeds and the other principal mode is to provide additional torque to the engine utilizing excess energy in the engine exhaust gas flow. In the boost mode turbine inlet valve 122 is open pump inlet valve 123 is closed and bypass valve 125 is closed so the output of hydraulic pump-motor is directed through pipe 118 to the hydraulic turbine portion hybrid turbocharger 1 to provide additional boost to the engine during low speed acceleration. In the additional torque mode turbine inlet valve 122 is closed bypass valve 125 is closed and pump inlet valve 123 is open. In order to prevent cavitations in high-speed pump blades 12 the pump inlet passage 35 is pressurized by hydraulic fluid supplied by lubrication pump 105 via open pump inlet pressurization valve 115. A combination of pump blades 12 and pump stator passage 131 produce high pressure hydraulic flow exiting, via pipe 95, of the pump portion of the hybrid turbocharger which drives pump motor 81 providing additional torque to the engine drive shaft.
Shown in
For engines between 1.2 and 1.8 liter displacement a need for this mode of operation is estimated to be during fast vehicle acceleration in the engine speed range between 1000 and 3000 RPM with corresponding turbocharger speed between 90,000 and 120,000 RPM. During the beginning of this mode at estimated 1000 RPM, the hydraulic turbine inlet valve 122 is open and hydraulic pump inlet valve 123 and hydraulic bypass valve 125 are closed. This forces all the hydraulic flow generated by the hydraulic pump/motor 81 to flow via high pressure hydraulic line 117 into the hydraulic turbine inlet port 33 and through hydraulic turbine blades 11 generating required power input into turbocharger shaft 15 shown in
As the engine RPM increases the hydraulic flow rate generated by the hydraulic pump/motor 81 increases proportionally to the engine RPM while need for hydraulic turbine assist power gradually decreases to zero toward 3000 RPM range. Hydraulic bypass valve 125 controlled by varying voltage signal gradually opens in response to decreasing voltage control to fully open at about 3000 engine RPM. Hydraulic bypass valve 125 is of the fail open type and with zero voltage input it stays fully open at which point the hydraulic turbine valve 122 closes with pump/motor 81 fully unloaded. Hydraulic turbine 11 is designed to produce up to 8 HP @ 100,000 RPM with hydraulic pump/motor 81 input of 9 GPM at 2100 psig with hydraulic turbine efficiency of approximately 75%.
Following table shows estimated hydraulic system parameters during the hydraulic turbine assist mode using 1.16 cu in/rev pump/motor 81:
Further increase in engine speed above approximately 3000 RPM operating at full throttle causes turbocharger gas turbine 73 to produce power in excess of the air compressor 62 power needed for full engine boost. In standard turbochargers this power excess is handled by the exhaust wastegate valve which essentially dumps the excess exhaust gas flow into the engine exhaust system.
In preferred embodiments of this invention the turbocharger wastegate valve and the wasted exhaust gas flow has been eliminated by using the excess power to drive via turbocharger shaft a high speed centrifugal pump blades 12 producing high pressure hydraulic flow which via hydraulic pump discharge channel 34 shown in
Following table shows estimated hydraulic system parameters during the hydraulic pump power recovery mode using 1.16 cu in/rev pump/motor 81:
Hydraulic gear pump-motors are commercially available from Berendsen Hydraulics, Santa Fe Spring, Calif. and other distributors. For automotive engine sizes from 1.2 liter to 1.8 liter a preferred choice is Hydraulic Motor/Pump type Volvo-VOAC Hydraulic Model F11-19 with displacement of 1.16 cu in/rev and overall efficiency for pump or motor operation in excess of 90% as shown in
Applicant estimates that the cost of the hydraulic turbine pump hybrid turbocharger system in mass production will be about $40 per vehicle. Gasoline mileage should be improved by about 10 percent. At gasoline prices of about $3.50 per gallon, savings, resulting from the improved gasoline mileage, will compensate for the cost of the system in about 5 to 10 months for a typical small automobile. At gasoline prices which can be much higher and for larger vehicles, the savings rate would be substantially greater.
The above table shows potential engine power recovery by using wasted exhaust flow in the hybrid hydraulic pump/turbine turbocharger. Additional power can be recovered by using the turbocharger exhaust heat in a steam turbine power loop or in thermo-electric power systems.
The reader should understand that the above descriptions are merely preferred embodiments of the present invention and that many changes could be made without departing from the spirit of the invention. For example the invention can be applied to a great variety and sizes of diesel engines stationary as well as motor vehicle engines. Many features of Applicants prior art patents that have been incorporated by reference herein could be utilized in connection with the present invention. For all of the above reasons the scope of the present invention should be determined by reference to the appended claims and not limited by the specific embodiments described above.
