Hybrid Automobiles 1 Hybrid Automobiles 2 Introductory Question Introductory Question If you connect an electric motor in a circuit If you connect an electric motor in a circuit � with a with a lightbulb lightbulb, is there a chance that spinning , is there a chance that spinning Hybrid Automobiles Hybrid Automobiles the motor will cause the the motor will cause the lightbulb lightbulb to light up? to light up? Yes Yes A. A. No No B. B. Hybrid Automobiles 3 Hybrid Automobiles 4 Observations about Hybrid Observations about Hybrid 5 Questions about Hybrid 5 Questions about Hybrid Automobiles Automobiles Automobiles Automobiles � A hybrid car propels itself on fuel or batteries A hybrid car propels itself on fuel or batteries � How does a hybrid car power its wheels? How does a hybrid car power its wheels? � It combines electrical and mechanical power It combines electrical and mechanical power � How does a hybrid car generate electric power? How does a hybrid car generate electric power? � It switches easily between fuel, batteries, or both It switches easily between fuel, batteries, or both � How does a hybrid car use that electric power? How does a hybrid car use that electric power? � � It can recharge its batteries during braking It can recharge its batteries during braking � How does a hybrid car manage that power? How does a hybrid car manage that power? � It can turn its engine off when not needed It can turn its engine off when not needed � If magnets don’t move, can they affect charge? If magnets don’t move, can they affect charge? � It can restart its engine quickly and easily It can restart its engine quickly and easily Hybrid Automobiles 5 Hybrid Automobiles 6 Question 1 Question 1 Combining Mechanical Power Combining Mechanical Power � How does a hybrid car power its wheels? How does a hybrid car power its wheels? � A hybrid automobile uses a machine that blends A hybrid automobile uses a machine that blends � � How does it combine engine and battery power? How does it combine engine and battery power? � rotary mechanical power from its fuel rotary mechanical power from its fuel- -burning engine burning engine � rotary mechanical power from its electric motors rotary mechanical power from its electric motors � r t r m � rotary mechanical power from its wheels r t r m rotary mechanical power from its wheels h ni h ni l p l p r fr m it r fr m it h h l l � That “transaxle” can transfer mechanical power That “transaxle” can transfer mechanical power between any of those devices in either direction! between any of those devices in either direction! 1
Hybrid Automobiles 7 Hybrid Automobiles 8 Clicker Question Clicker Question The Transaxle The Transaxle � A hybrid car’s transaxle is a gear assembly that A hybrid car’s transaxle is a gear assembly that � You and a friend are arm wrestling You and a friend are arm wrestling— —trying to trying to twist each others arms down to the table. When twist each others arms down to the table. When � couples together its engine, motors, and wheels couples together its engine, motors, and wheels is your arm doing work on your friend’s arm? is your arm doing work on your friend’s arm? � conveys mechanical power between those devices conveys mechanical power between those devices � replaces the transmission of a normal car � r pl r pl replaces the transmission of a normal car th tr n mi i n f th tr n mi i n f n rm l n rm l r r A. As you are winning As you are winning A. B. As your friend is winning As your friend is winning B. C. While your arms are both motionless While your arms are both motionless C. D. Throughout the match Throughout the match D. Hybrid Automobiles 9 Hybrid Automobiles 10 Rotary Power Rotary Power Question 2 Question 2 � Recall that to provide rotary power to a machine Recall that to provide rotary power to a machine � How does a hybrid car generate electric power? How does a hybrid car generate electric power? � you must exert a torque on that machine you must exert a torque on that machine � in the direction of its angular velocity. in the direction of its angular velocity. � The transaxle allows engine, motors, and wheels Th The transaxle allows engine, motors, and wheels Th l l ll ll i i d d h h l l � to exert torques on one another to exert torques on one another � as they turn in various directions at various speeds as they turn in various directions at various speeds � and thereby transfer rotary power to one another. and thereby transfer rotary power to one another. � Power can flow in any direction via the transaxle! Power can flow in any direction via the transaxle! � Hybrid Automobiles 11 Hybrid Automobiles 12 Clicker Question Clicker Question Generating Electricity Generating Electricity � A coil of wire forms a closed circuit with a A coil of wire forms a closed circuit with a � Recall that changing magnetic fields Recall that changing magnetic fields lightbulb lightbulb. If you sweep the north pole of a bar . If you sweep the north pole of a bar � produce electric fields, produce electric fields, magnet past the coil of wire, the magnet past the coil of wire, the lightbulb lightbulb will will � which propel currents through conductors, which propel currents through conductors, � which produce magnetic fields. which produce magnetic fields. hi h pr d hi h pr d m m n ti fi ld n ti fi ld � � Changing Changing magnetic effects magnetic effects induce induce currents currents A. blink once. blink once. A. � Moving magnets have changing magnetic fields Moving magnets have changing magnetic fields B. blink twice. blink twice. B. � and can induce currents in coils of wire and can induce currents in coils of wire C. not blink at all. not blink at all. C. � with magnetic fields that oppose the moving magnets. with magnetic fields that oppose the moving magnets. � Mechanical power becomes electrical power! Mechanical power becomes electrical power! 2
Hybrid Automobiles 13 Hybrid Automobiles 14 An AC Generator An AC Generator Question 3 Question 3 � An AC Generator resembles a transformer An AC Generator resembles a transformer � How does a hybrid car use that electric power? How does a hybrid car use that electric power? � except that it has no primary coil except that it has no primary coil � Does it need both generators and motors? Does it need both generators and motors? � and instead uses a spinning magnet and instead uses a spinning magnet � How different are generators and motors? How different are generators and motors? � to induce AC current to induce AC current in its secondary coil. in its secondary coil. � Magnet rotation speed Magnet rotation speed sets the AC frequency. sets the AC frequency. � Magnet strength, turns Magnet strength, turns in the coil, and rotation in the coil, and rotation speed set voltage rise. speed set voltage rise. Hybrid Automobiles 15 Hybrid Automobiles 16 An AC Motor An AC Motor Introductory Question Introductory Question (revisited) (revisited) � An AC Motor resembles a transformer An AC Motor resembles a transformer If you connect an electric motor in a circuit If you connect an electric motor in a circuit � with a with a lightbulb lightbulb, is there a chance that spinning , is there a chance that spinning � except that it has no secondary coil except that it has no secondary coil the motor will cause the the motor will cause the lightbulb lightbulb to light up? to light up? � and instead uses a spinning magnet and instead uses a spinning magnet � to obtain power from � t to obtain power from t bt in p bt in p r fr m r fr m its primary coil. its primary coil. Yes Yes A. A. � AC frequency sets the AC frequency sets the No No B. B. Magnet rotation speed. Magnet rotation speed. � Magnet strength, turns Magnet strength, turns in the coil, and rotation in the coil, and rotation speed set voltage drop. speed set voltage drop. Hybrid Automobiles 17 Hybrid Automobiles 18 Generators = Motors Generators = Motors Question 4 Question 4 � If generators and motors look similar, If generators and motors look similar, � How does a hybrid car manage that power? How does a hybrid car manage that power? � that’s because they’re basically the same device! that’s because they’re basically the same device! � How do the batteries, motor/generators, engine, and How do the batteries, motor/generators, engine, and wheels all act together to propel the vehicle? wheels all act together to propel the vehicle? � they differ only in the direction of power flow they differ only in the direction of power flow � If you twist it forward, it acts as a generator If If you twist it forward, it acts as a generator If i i i f i f d i d i � You do work on it and transfer power to it You do work on it and transfer power to it � Lenz’s law: magnetic effects twist you backward Lenz’s law: magnetic effects twist you backward � If you twist it backward, it acts as a motor If you twist it backward, it acts as a motor � You do negative work on it and extract power from it You do negative work on it and extract power from it � Lenz’s law: magnetic effects twist you forward Lenz’s law: magnetic effects twist you forward 3
Recommend
More recommend
