A successful solution for the implementation of a parallel hybrid drive of Hybrid Synergy Drive (HSD) was found by the developers of Toyota concern. Company engineers are a consecutially parallel scheme, combining in their actuator the best qualities of both serial and parallel construction.
The developers of the parallel drive took the diagram of a parallel hybrid and added a power-divider (planetary mechanism) and a separate generator. As a result of this development, the hybrid acquires functions of a serial transmission, where the car is performing a throblinking and driving at low speeds, only for the electric motor thrust. The internal combustion engine shall be activated when the vehicle is in constant speed or at high speeds.
In high load modes, (such as the mountain, acceleration, etc.) the hybrid begins to operate as a parallel, fueling the electric motor from the battery. The hybrid drive train provides a separate generator that is used to charge the battery. Electric motor enters the work only for the wheel drive and for the recovery of energy (regenerative braking).
The planetary mechanism allows a portion of the power to be transferred to the main wheels, and the remainder to the generator, which either charges the battery or feeds the electric motor.
Under different conditions of traffic for optimal operation, the power supply from both sources is regulated by the on-board computer system. In such a parallel circuit, the IVS is only activated in the most efficient regimes, and most of the time the hybrid works on the electric motor. Therefore, the hybrid system may be used in a hybrid system with a lower capacity.
Toyota Prius is one of Toyota's most famous cars with Hybrid Synergy Drive
For its sequence of parallel transmission, Toyota engineers chose the engine, which is not standard for most of the BAR cycle Otto, but in the more economical Atkinson cycle.
Thus, when the engine is running on the Otto cycle, the piston at the stroke of the inlet downward, creates a vacuum in the cylinder that is sucked into it by fuel and air. In low-turn mode, with almost completely closed throttle, there are pumpable losses.
In addition, fresh air of cylinders is also degraded, leading to higher fuel consumption and increased harmful emissions to the atmosphere. When the piston is reached, the lower dead point (NRMM) is closed by the intake valve. During the tact of the exhaust, when opening the discharge valve, the exhaust gas is still under pressure, but their energy is wasted. This effect is called the loss of the release.
In the engines of the Atkinson cycle, the intake valve on the intake cycle is closed much later than NRMM, which has a number of undeniable advantages.
This is a reduction in the loss of the pump, as during the piston up after passing NRMM, part of the mixture is not emitted into a silencer, but is pushed back into the intake manifold and can be used in another cylinder. In addition, a combustible mixture shall be taken away with it and a portion of the heat from the cylinder wall. As the duration of the compression clock is reduced relative to the stroke, the engine works on a loop with a higher degree of expansion. The energy of the exhaust gas is used for a longer period of time, that is, the loss of output is reduced. This leads to better environmental performance, more efficiency and efficiency, but less capacity. But this actually needed to be achieved by the developers of the parallel drive. Since Toyota's motor is used only in low-loaded modes, the Atkinson cycle's flaws have little effect.
Deficiencies in sequential-parallel drive
The higher cost of the components;
The need for a separate generator;
The presence of the massive and the overall battery unit;
a more sophisticated computer system.
Interesting facts about parallel hybrid-drive layout
The development of the HSD hybrid drive by Toyota acquired Nissan and Ford and used the development of Nissan Altima and Ford Escape Hybrid.
The Toyota Prius model is the leader among hybrid vehicles with fuel consumption in the city of 4l/100 km. In general, this is the first car with such fuel economy measures, where the fuel consumption in the urban cycle is less than that of the road.
Consistently parallel to the hybrid power train, thanks to the application of the special element of the electric motor and the DSS (say, asymmetrical planetary differential) to redistribute the outgoing power flows. The coking device is able to redistribute the power flows between the thermal engine and the electrical unit and the two flow points to the driving wheels (electromechanical and mechanical), while passing the power in any direction.
Such a scheme is good in that it allows to operate both from one source of energy and from two sides, and the moment can be transmitted both as an electric motor and an internal combustion engine, or one of them (any).
A hybrid drive scheme specifies a high economy of operation, increased flexibility in different modes of operation in the system of traction power. But, at the same time, this system of sequential-parallel drive requires the creation of expensive and complex mechanical elements, and is sufficient both in the design and implementation.
The development and implementation of hybrid drives provided an opportunity to advance the development of the car of the future by several steps forward. Thus, hybrid vehicles have developed compact and intensive accumulator batteries, new technologies for the rapid charging of batteries from an external source, further energy reuse systems, new powerful electric motors and the most light bodies.
