Toyota Hybrid Synergy Drive
Case study: Toyota Hybrid Synergy Drive
Introduction
Hybrid Synergy Drive, (HSD) is a set of hybrid car technologies developed by Toyota. HSD technology is used in the Prius, Highlander Hybrid sport-utility vehicle (SUV), Camry Hybrid, Lexus RX 400h, Lexus GS 450h, and Lexus LS 600h/LS 600hL automobiles. It combines an electric drive and a continuously variable transmission. Toyota describes HSD-equipped vehicles as having E-CVT (Electronically-controlled Continuously Variable Transmission). We can classify the HSD-equipped vehicles as ―combined HEV‖. The Synergy Drive is a drive-by-wire system with no direct mechanical connection between the engine and the engine controls: both the gas pedal and the gearshift lever in an HSD car merely send electrical signals to a control computer. HSD is a refinement of the original Toyota Hybrid System (THS) used in the 1997–2003 Toyota Prius. As such it is occasionally referred to as THS II. The name was changed in anticipation of its use in vehicles outside the Toyota brand (e.g. Lexus; the HSD-derived systems used in Lexus vehicles were termed Lexus Hybrid Drive since 2006). The Lexus Hybrid Drive system has since been touted for its increase in vehicle power as well as environmental and efficiency benefits.
1. Theory of operation
HSD replaces a normal geared transmission with an electromechanical system. All car powertrains drive a driveshaft that turns the drive wheels of the car. Because an internal combustion engine delivers energy best only over a small range of torque and speed, the crankshaft of the engine is usually attached to a switchable gear train that matches the needed torque at the wheels to the torque that can be delivered by the engine. HSD replaces the gear box, alternator and starter motor with a pair of electrical motor-generators (MG), a computerized shunt system to control them, a mechanical power splitter that acts as a second differential, and a battery pack that serves as an energy reservoir.
Introduction
Hybrid Synergy Drive, (HSD) is a set of hybrid car technologies developed by Toyota. HSD technology is used in the Prius, Highlander Hybrid sport-utility vehicle (SUV), Camry Hybrid, Lexus RX 400h, Lexus GS 450h, and Lexus LS 600h/LS 600hL automobiles. It combines an electric drive and a continuously variable transmission. Toyota describes HSD-equipped vehicles as having E-CVT (Electronically-controlled Continuously Variable Transmission). We can classify the HSD-equipped vehicles as ―combined HEV‖. The Synergy Drive is a drive-by-wire system with no direct mechanical connection between the engine and the engine controls: both the gas pedal and the gearshift lever in an HSD car merely send electrical signals to a control computer. HSD is a refinement of the original Toyota Hybrid System (THS) used in the 1997–2003 Toyota Prius. As such it is occasionally referred to as THS II. The name was changed in anticipation of its use in vehicles outside the Toyota brand (e.g. Lexus; the HSD-derived systems used in Lexus vehicles were termed Lexus Hybrid Drive since 2006). The Lexus Hybrid Drive system has since been touted for its increase in vehicle power as well as environmental and efficiency benefits.
1. Theory of operation
HSD replaces a normal geared transmission with an electromechanical system. All car powertrains drive a driveshaft that turns the drive wheels of the car. Because an internal combustion engine delivers energy best only over a small range of torque and speed, the crankshaft of the engine is usually attached to a switchable gear train that matches the needed torque at the wheels to the torque that can be delivered by the engine. HSD replaces the gear box, alternator and starter motor with a pair of electrical motor-generators (MG), a computerized shunt system to control them, a mechanical power splitter that acts as a second differential, and a battery pack that serves as an energy reservoir.