BMW through the implementation of BMW EfficientDynamics strategy, has made some progress in reducing fuel consumption and CO2 emissions, its hybrid models have CO2 emissions at or below 140 g / km. BMW dynamic efficiency not only in high-precision fuel injection, and to automatically start and stop energy braking energy recovery techniques, in the long run, high dynamic BMW further comprising using the hydrogen fuel with no emissions. In the medium term, the BMW ActiveHybrid hybrid technology is still some room for development. Here we combine models in the BMW ActiveHybrid X6 E72 brief introduction to the BMW hybrid technology, we hope readers can understand how ldquo introduced by the engine and the motor-driven power these; hybrid & rdquo;.
FIG 1
E72 model BMW X6 is actually in the traditional model adds X6 motor (active transmission), and the high-voltage battery supply control means, enabling the hybrid, play the role of energy conservation and drivability.
FIG. 2
1. Active transmission
E72 BMW hybrid technology is the power output of the engine and the motor is performed by mixing the active transmission, no active transmission is a simple transmission, but the power source of the vehicle . With conventional automatic transmissions active transmission from the mechanical point of view is very similar to the structure (FIG. 1), but the former is more than two motors (FIG. 2), these two motors may function according to need between the motors, generators and shifting element conversion. A conventional automatic transmission shift is constrained to achieve some of the elements of the rotation of the planetary gear train by mechanical means, through the active transmission is an electromagnetic field to change the motor power mixed manner in the active control of the planetary gear train of the transmission elements to achieve . 3, the first rotor and the motor A planetary row sun gear and second planetary gear connected integrally rows; B and the rotor of the motor of the second planetary row sun gear of the second planetary row sun gear 3 as a single entity, as long as controlling the rotational speed of the motor 2, the speed reduction ratio can be infinity from the active transmissionLarge 0.723 to continuous change, and this change is constantly changing, it can better achieve the aspirations of the driver’s control, which is unmatched by any mechanical transmission. As a result of active transmission, the conventional vehicle starter, a generator, a torque converter and shift quality improvement means become superfluous.
Figure 3
Figure 4
FIG. 5
Figure 6
when the engine starts, motor B in addition to driving the vehicle is running and driven by the motor A power, but which part of the power used starting the engine (FIG. 4), after starting the engine of the vehicle will enter the hybrid drive mode. When the engine is running, and the vehicle is stationary, since all three elements of the planetary transmission none constrained row, the output power of the engine is not transmitted (FIG. 5), the reduction of the transmission ratio at this time is infinite. A B input when the motor speed, second and third planetary row sun gear B is active constrained motor, when the output power of the engine can be transmitted to the wheels, the vehicle starts running. With the change of the rotational speed of the motor B, decreasing the reduction ratio of the transmission, thus the output speed of the engine to achieve a continuous transmission (the CVT), while the engine power after the power of the motor B to the wheel summed output (FIG. 6). Since the motor torque at zero speed can reach the maximum value, which may provide sufficient power to start the vehicle. When the engine stall when the vehicle is traveling in electric mode, motor B is the only power source (FIG. 7). When the vehicle braking, engine output power is not off the oil, motor A controls the rotation of the planetary gear B on the motor vehicle is braked, while converting the vehicle’s kinetic energy into electrical energy stored in the high-voltage battery (FIG. 8). When the vehicle constant speed, to reduce power consumption to engine-driven manner, when two motors are not involved in the work (FIG. 9).
Figure 7
Figure 8
FIG. 9
2. The high-voltage battery unit
10 [123 ]
11
is a high-voltage high-voltage battery accumulator, which basic units 260 in series (rated voltage 1.2 V ) to give 312 V rated voltage. Each module 10 electrolytic cells. Modules 13 arranged side by side to form one, two superposed arrangement, constitute the entire high voltage battery package (FIG. 10). The basic unit with nickel-hydrogen storage technology, which has a high energy density and the charging and discharging current characteristics, which is a prerequisite in a hybrid vehicle driving achieve high electrical power, the electrical structure shown in Figure 11. High-voltage battery temperature characteristic curve shown in Figure 12, in a low temperature region and high temperature region of the output and input of the battery will decline, particularly also reduces battery life in a high temperature region. By electrolyte battery cooling system maintaining the temperature at 35 ~ 45 ℃, when a conventional cooling capacity is insufficient, air conditioning and refrigeration systems are added to battery cooling system (FIG. 13).
12
13
[ 123]
3. The power supply system
14
15
BMW E72 models have two voltage levels, a high level voltage of about 300 V, and the other is the familiar 14 V low voltage level (FIG. 14). APM auxiliary power supply unit is responsible for implementing energy conversion (FIG. 15) between the two voltage levels. PEB supply electric control box controls the high voltage power in all operating states, the motor bidirectional energy flow, speed and torque of the two motors and the electric oil pump hybrid power machine (FIG.16). And these units arranged in alignment situation shown in Figure 17.
16
17
4. The hybrid braking system
E72 BMW vehicle brake system for a vehicle not only reliable, stable deceleration, also enables the braking energy of the vehicle is not converted into heat, but by the active transmission of the motor converted into electrical energy. To cope with E72 full-hybrid drive mode for maximum fuel economy, braking system must recycle as much braking energy. At the same time, also to obtain a unique BMW brake pedal feel under all driving conditions and vehicle speed range, the exact quantitative control of the braking force and excellent deceleration characteristic.
18
To meet these requirements, the other portion of the brake pedal is no longer between the braking system (brake booster) permanently maintain mechanical contact (FIG. 18). This is an electronic servo-brake control system, detecting driver’s braking requirement electronically, and then divided into the braking request hydraulic part and the electrical part. Electric conversion section by a motor for the active transmission of electrical energy and stored in high voltage battery, hydraulic pressure generating deceleration portion (19) by a conventional service brake. In all cases with a percentage of 80 to 90 percentage BMW E72 braking system braking energy can be recycled, conversely, the braking energy at all, only 10 percentage to 20 percentage by waste heat into the service brake.
19
(Daijia Wen Hu Yong)