Abstract:
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. A hybrid turbocharger unit includes an engine exhaust gas turbine driving a compressor, a hydraulic turbine and a hydraulic pump, all mounted on said turbocharger shaft. The hydraulic pump motor functions as a hydraulic pump driven by the drive shaft of the engine to provide additional boost to the turbocharger unit at low engine speeds and functions as a hydraulic motor driven by the turbocharger pump to provide additional torque to the engine drive shaft high engine speeds. Additionally, this system provides for brake energy recovery by storing the energy absorbed during the breaking cycle and releasing it back to the pump motor when required during the subsequent acceleration cycle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Provisional Application Ser. No. 61/461,564 filed Jan. 20, 2011 and is a continuation in part of Ser. No. 12/930,870 filed Jan. 19, 2011. 
     
    
     FIELD ON THE INVENTION 
       [0002]    The present invention relates to modern automotive vehicles and in particular to systems such as turbocharger systems for improving efficiency and performance. 
       BACKGROUND OF THE INVENTION 
       [0003]    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. 
         [0004]    Some significant improvements are provided with electric-internal combustion hybrid vehicles which include an electric motor-generator and a high energy battery system that converts braking energy into stored electric energy to assist the internal combustion engine. The problem is the motor-generator and the battery system adds considerably to the cost and weight of the vehicle and occupies substantial space in the vehicle. 
         [0005]    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 FIG. 14 of that patent. 
         [0006]    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 and there is also a need for a lighter, smaller, less expensive alternative to the hybrid vehicle for recovering braking energy. 
       SUMMARY OF THE INVENTION 
       [0007]    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 portion of the pump motor provides additional boost to the turbocharger unit driving additional air into the engine for acceleration at low engine speeds. Additionally, this system provides for brake energy recovery by storing the energy absorbed during the breaking cycle and releasing it when required during the subsequent acceleration cycle. 
         [0008]    Preferred embodiment include a high pressure hydraulic accumulator in hydraulic communication with the hydraulic pump motor and adapted to accumulate high pressure hydraulic fluid pumped by the hydraulic pump motor during vehicle braking cycles and to supply the high pressure fluid back to the hydraulic pump motor during vehicle acceleration cycles to add torque to the drive shaft recovering a portion of vehicle kinetic energy loss during the braking cycles. Applicant estimates that the efficiency of this brake energy recovery will be about the same or better than the brake energy recovery efficiency of electric hybrid vehicles currently on the market, but at much lower cost, much less weight and with much more compact components. 
         [0009]    Preferred embodiments of this invention utilize 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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows hybrid turbocharger—engine overall system. 
           [0011]      FIG. 2  shows preferred embodiment of integrated hydraulic turbine—power recovery pump hybrid design. 
           [0012]      FIG. 3  shows simplified schematics of the novel hybrid hydraulic turbine-pump system. 
           [0013]      FIG. 4  is a cross sectional drawing showing a preferred embodiment of the very high speed hybrid turbocharger. 
           [0014]      FIGS. 5A and 5B  show performance of the fixed displacement hydraulic pump motor that is either recovering excess power from the turbocharger or is assisting in accelerating the turbocharger when needed. 
           [0015]      FIG. 6  shows simplified schematics of the overall hybrid turbocharger-brake energy recovery system. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     First Preferred Embodiments 
       [0016]    A first preferred embodiment of the present invention can be described by reference to the figures.  FIG. 1  shows some of the important features of the present invention. A hydraulic turbine-pump hybrid turbocharger is shown at  1  in  FIG. 1 . Turbocharger  1  is driven primarily by engine exhaust line  71  from engine  68 . The exhaust gases from the engine are directed through blades  58  of the exhaust gas turbine portion of turbocharger  1 . Exhaust gases exit the turbocharger as shown at  3  in  FIG. 1 . Environmental air is drawn into the compressor portion of turbocharger as shown at  5  and is compressed by compressor blades  62 . Compressed air is directed to air cooler  65  via pipe  64  and cooled compressed air is directed into engine  68  via pipe  70 . The above portion of the turbocharger is all conventional. 
         [0017]    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. 
         [0018]    During the entire engine operation the lubrication pump  105  supplies hydraulic fluid (oil) to turbocharger bearings via line  86  shown on  FIG. 1 . Two turbocharger bearings  57  and the compressor side bearing  52  shown on  FIG. 4  are being supplied with oil by line  86 . Oil drain lines  87  and  113  provide for drain flow out the three bearings and into the bearings venturi throat  101  where the low suction pressure created by additional flow from lubrication pump  105  pumps all bearings drain flow into oil tank  88 . Bearing drain flow may contain small amounts of exhaust gas and compressor air that leaks through turbine shaft seal  72  and compressor shaft seal  77  shown in  FIG. 4 . Oil tank  88  is vented at atmospheric pressure into a line connected to the air compressor inlet  5  to eliminate any gas emission. 
         [0019]    During the vehicle breaking cycle the hydraulic pump and turbine portions of the turbocharger are hydraulically isolated by shutting hydraulic valves  123  and  122  and by action of hydraulic check valves  92  and  134  shown in  FIG. 6 . Hydraulic energy is stored in accumulator  131  by pumping action of the hydraulic pump/motor  81  that at the same time provides breaking action for the vehicle. Accumulator valve  132  provides for control of degree of breaking action. At the end of the breaking cycle the hydraulic pump/motor  81  is fully unloaded by opening bypass valve  125 . Stored energy in accumulator  131  is released during the acceleration cycle by fully or partially opening of the accumulator valve  132  providing high pressure hydraulic flow into the hydraulic pump/motor  81  that is directly coupled to the engine  68  shown in  FIG. 1 . During the acceleration cycle hydraulic turbine inlet valve  122  can be partially or fully open as needed to assist the turbocharger turbine  51  in providing required engine boost produced by the turbocharger compressor  62  shown in  FIG. 1 . 
       Hydraulic Pump and Turbine Portions of Hybrid Turbocharger 
       [0020]      FIG. 2  is a cross sectional drawing of an enlarged portion  14  of the hybrid turbocharger  1  shown in  FIG. 1 .  FIG. 2  shows in detail the hydraulic turbine portion (on the right) and the hydraulic pump portion (on the left). The hydraulic turbine-pump assembly  14  incorporates hydraulic turbine blades  11  solidly attached to hydraulic turbine wheel  41  and hydraulic pump blades  12  solidly attached to hydraulic pump wheel  42 . Both plastic wheels  41  and  42  are solidly anchored inside pump side steel rotor  37  and turbine side steel rotor  38  to form an integral rotor pump-turbine assembly. Steel ring  43  serves as a retaining ring to hydraulic pump wheel  42 . Turbine-pump stator ring  13  containing pump stator passages  131  and turbine nozzles  132  is contained inside hydraulic turbine housing  48  and hydraulic pump housing  47 . Pump side journal bearing  52  is lubricated via oil passage  86  and drain passage  87 . Pump inlet passage  35  and pump discharge passage  34  are contained in the hydraulic pump housing  47  and turbine inlet passage  33  and turbine discharge passage  17  are contained in the hydraulic turbine housing  48 . Turbine shaft seal  59  and cover ring  51  seal the turbine discharge passage  17 . 
         [0021]    Shown in  FIG. 3  is a simplified schematic of the hydraulic turbine-pump system of the present invention. Hydraulic gear pump motor  81  is directly coupled to the engine shaft and provides hydraulic power to hybrid turbocharger turbine blades  11  via turbine inlet line  118  when turbine inlet valve  122  opens and pump inlet valve  123  closes. Alternatively, when turbine inlet valve  122  closes and pump inlet valve  123  opens; the pump blades  12  of hybrid turbocharger  1  provide high pressure hydraulic flow to the hydraulic gear pump-motor  81  that in turn transmits power to the engine shaft as shown in  FIG. 1 . High speed hydraulic centrifugal pump blades  12  are part of the same wheel assembly with hydraulic turbine blades  11 . As explained above, turbocharger shaft  15  can be driven by turbine blades  11  when additional turbocharger power is required at low engine speeds or the turbocharger shaft can alternatively drive centrifugal pump blades  12  when excess turbocharger power is available at higher engine speeds. 
       Modes of Operation 
       [0022]    There are three principal modes of operation of the present invention. One principal mode is the hybrid turbocharger boost mode to provide boost to the turbocharger at low engine speeds where energy from the engine drive shaft produces high pressure fluid to boost the turbocharger. The second mode is the engine assist mode where the hybrid turbocharger provides high pressure fluid to the turbine portion of the pump motor  81  to provide additional torque to the engine drive shaft utilizing excess energy in the engine exhaust gas flow. In a third mode, the braking energy recovery mode, high pressure fluid is driven into and stored an accumulator during braking actions by the hybrid turbocharger and this high pressure fluid is during a subsequent acceleration directed to the turbine portion of the pump motor  81  to provide additional torque to the engine drive shaft. 
       Hybrid Turbocharger Boost Mode 
       [0023]    As shown in  FIG. 3  in the hybrid turbocharger 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 charge additional compressed air into the engine to provide additional boost to the engine during low speed acceleration. 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  FIG. 2 . During this mode of operation the hydraulic bypass valve  125  can be modulated from fully closed to fully open position via variable voltage signal. For this application a Model PV72-31 Normally Open Proportional Flow Control Valve is chosen as hydraulic bypass valve  125 . This valve is manufactured and marketed by HydraForce, Inc., Lincolnshire, Ill. 
         [0024]    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%. 
         [0025]    Following table shows estimated hydraulic system parameters during the hydraulic turbine assist mode using 1.16 cu in/rev pump motor  81 : 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 Engine RPM 
                 1500 
                 2000 
                 3000 
                 4000 
               
               
                 Pump/motor RPM 
                 1818 
                 2424 
                 3636 
                 4848 
               
               
                 Pump motor gpm 
                 8.21 
                 10.96 
                 16.43 
                 21.9 
               
               
                 % bypass valve 125 
                 0 
                 11 
                 70 
                 100 
               
               
                 Hydr. turb. flow gpm 
                 8.21 
                 8.54 
                 4.93 
                 0 
               
               
                 Hydr. turb. P1 psig 
                 1960 
                 2163 
                 720 
                 0 
               
               
                 Hydr. turb. effic. % 
                 60 
                 75 
                 40 
                 0 
               
               
                 Hydr. turb. power HP 
                 5.75 
                 8.1 
                 1.1 
                 0 
               
               
                   
               
             
          
         
       
     
       Engine Assist Mode 
       [0026]    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 the engine assist 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. 
         [0027]    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  FIG. 2  and high pressure hydraulic line  95  shown in  FIG. 1  drives the pump motor  81  that transmits this power into the engine drive shaft via pump motor  81 . Before initiation of the power recovery mode hydraulic bypass valve  125  is open and turbine inlet valve  122  and pump inlet valve  123  are closed. In order to prevent cavitation in the high speed hydraulic pump blades  12  the pump inlet passage  35  must be pressurized to approximately 60 to 90 psig which is accomplished by opening pump inlet pressurization valve  115  in sequence with opening pump inlet valve  122  and closing hydraulic bypass valve  125 . This allows for lubrication pump  105  to pressurize pump inlet passage  35  via lubrication line  86  which allows hydraulic pump blades  12  to start pumping hydraulic fluid via high pressure hydraulic line  95  into the hydraulic pump motor  81  thus producing mechanical power transmitted to the engine. 
         [0028]    Following table shows estimated hydraulic system parameters during the hydraulic pump power recovery mode using 1.16 cu in/rev pump/motor  81 : 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 Turbocharger RPM 
                 140,000 
                 150,000 
                 160,000 
               
               
                 Hydr. flow gpm 
                 21.5 
                 26.3 
                 30.5 
               
               
                 Hydr. press. psig 
                 620 
                 820 
                 980 
               
               
                 Hydr. pump eff. % 
                 60 
                 70 
                 70 
               
               
                 Pump inlet spec. speed 
                 15,000 
                 15,000 
                 15,000 
               
               
                 Pump inlet press. psia 
                 53 
                 72 
                 89 
               
               
                 Pump HP 
                 9.0 
                 18.0 
                 25.0 
               
               
                   
               
             
          
         
       
     
       Breaking Energy Recovery Mode 
       [0029]      FIG. 6  is a simplified schematic showing describing the function of a preferred hybrid turbocharger-brake energy recovery system during the braking energy recovery mode of operation. This system is an expansion of the hydraulic turbine-pump system shown in  FIG. 3 . As shown in  FIG. 6  during an acceleration mode when driven by high pressure hydraulic fluid discharged from accumulator  131  into pump motor  81  the turbocharger can provide additional boost to the engine if required. For this mode of operation the hydraulic turbine control valve  122  modulates high pressure hydraulic flow through turbine blades  11 . Turbine discharge valve  182  is wide open allowing for turbine discharge flow to flow freely into hydraulic storage tank  153 . During this mode valve  177  is closed and valve  152  is open. Valve  123  is closed preventing any flow into pump blades  12 . As most vehicular breaking systems use hydraulic actuated brakes, when brake pedal  171  is applied the pressure transducer  172  sends a signal to the controller  173  opening accumulator valve  132  and closing the bypass valve  125  and valve  152  leading to the hydraulic storage tank  153 . Hydraulic fluid is now free to flow from hydraulic storage tank  153  via line  154  into the inlet of hydraulic pump/motor  81  where the fluid is pressurized and delivered into accumulator  131 . 
         [0030]    During a subsequent acceleration cycle stored accumulator energy is released by engine control system signal to the controller  173  which opens the accumulator valve  132  allowing for high pressure hydraulic fluid to drive the hydraulic pump/motor  81  increasing the total engine torque. During this cycle valve  152  is open and valve  177  is closed allowing returning hydraulic fluid to flow via lines  175 ,  127  and  151  back into hydraulic storage tank  153 . 
         [0031]    During a typical braking cycle hydraulic fluid is pumped under pressure by pump-motor  81  into accumulator  131 . As shown in  FIG. 5A , the hydraulic efficiency of pump-motor  81  averages about 90 percent. During the energy recovery cycle (acceleration) the hydraulic efficiency averages about 90 percent. Therefore, the total energy loss during the braking and acceleration cycles is about 20 percent of the total energy absorbed during the total braking and acceleration cycle with an energy recovery of about 80 percent. Applicant expects that this energy recovery will be better than the braking energy recovery of existing hybrid electrical vehicles currently on the market. 
         [0032]    Accumulators of the type needed for this application are available from supplier such as Structural Composites Industries with offices in Pomona Calif. and Worthington Cylinder Corporation with offices in Columbus, Ohio. These accumulators come in a variety of sizes. If we design for a braking cycle of about 15 seconds and the pump-motor flow is about 10 gpm at a 3,000 engine rpm, then the accumulator storage capacity would be about 2.5 gallons (i.e. 15/60 minutes×10 gpm=2.5 gallons). 
       Components 
       [0033]    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  FIGS. 5A and 5B . The F11 Series Pump/Motors are available with displacements from 0.30 to 14.8 cu in/rev that would be able to cover requirements of engines smaller than 1.2 Liter and engines larger than 1.8 Liter. For the T03 to T04 size turbochargers the Hydraulic Turbine Assist mode of operation is projected in the turbocharger speed range between 90,000 and 120,000 RPM and the Power Recovery Pump mode between 130,000 and 190,000 RPM speed range. For engines between 1.2 and 1.8 Liter displacement this would roughly correspond to the engine speed range between 1000 to 3000 RPM for hydraulic turbine assist mode and between 3000 to 6000 RPM for hydraulic pump power recovery mode. Typical accumulator suppliers are referred to in the above section. 
       The System Quickly Pays for Itself 
       [0034]    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. 
       Potential for Additional Power Recovery 
       [0035]    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. 
       Variations 
       [0036]    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.