new Nissan cars Sunshine held in December 2010 in a ceremony on the Guangzhou Auto Show, the car uses a new platform models, models for the L02B. Not only does it have in terms of vehicle power larger increase, HR15DE equipped with dual injector engine, and the world’s first planetary gear by CVT belts, but also in the application of information technology is also a breakthrough. In addition, the model is still deep potential on many details, in the case of cost increases very significantly improve the overall performance of the vehicle. Now a brief introduction to some of the technical highlights of the vehicle.
1 Engine
(1) Injector
The model engine model adopted for the HR15DE, this engine for the first time using a dual injector fuel injection (Figure 1). Which is notable features: only enhance the fuel atomization effect, but also increases the area of the fuel into the cylinder during contact with air, the mixture gas gasification better make combustion more fully, higher engine efficiency .
The engine fuel pressure in the injector fuel rail is 350 kPa, the fuel pressure is generally higher than the engine. This enables better fuel atomization, the atomization of fuel can be reduced to a diameter of 30 mu; m, while the diameter of the ordinary fuel injector atomization generally at 70 mu; m or more. Each injector 18 has a fuel injection holes, which extra than ordinary fuel injector spray holes 6, so that a single injector at up to 300 kPa static flow 157 ml / min. Then, when operating in a dual fuel injector, the fuel flow rate can reach 314 ml / min. Thus, such injector design, both to ensure good atomization, but there is enough fuel flow, so that the engine control system under various conditions can be easily controlled.
(2) lubrication system
The engine lubrication system in addition to their lube, but also provides supplemental cooling effect. Ejecting lubricating oil to a position below the piston from the cylinder (FIG. 2), the heat of the combustion chamber can passThe lubricating oil passing through the top of the piston, this part of the heat away by the lubricant oil and cooling. Such that the temperature of the combustion chamber is reduced, thereby improving the resistance to knocking of the engine. When the engine requires a large torque output, due to the increase in the cylinder intake mixture gas, knocking tendency to increase, but a result of these measures to reduce engine knock tendency, so that the engine does not have to be avoided by retarding spark knock, in this way the power of the engine response is more perfect.
(3) of the cylinder head and the piston
The engine designed by the cylinder head and the piston top, enhanced turbulent effect (FIG. 3). When the intake gas flow through the airway of the cylinder head, at a portion close to the airway valve port throttling were modest, which can excessively increase in intake resistance under the premise that the air velocity at the entrance of the gas increases. Top of the piston touches the gas flow is accelerated specially designed shape of the recess, effectively form a turbulent flow. Inertia gas stream, the mixture gas in the cylinder annular flow. Such mixture gas in a limited period of time, extending from the gasification, to improve the effect of gasification, so that the combustion more fully, better fuel economy.
(4) catalytic converter
The engine catalytic converters have changed in the details, border honeycomb shape to a square instead of a conventional hexagonal (FIG. 4). We know, at the same circumferential length, the largest area of a circle, so that the honeycomb catalytic converters in general have adopted a circular, to maximize the capacity of the gas stream. Because closer to circular than hexagonal square, so in the case of the border the same diagonal length, the former can increase the diameter of the center hole. The improvements, not only reduces the air flow resistance of the catalyst, but also saves the amount of rare metals, reduce the cost. In the exhaust gas stream is improved without affecting the purification performance, thereby increasing engine power output. Since the venting capacity of the catalytic converters has been improved, so that the exhaust back pressure is reduced. To maximize the benefits of this improvement brought by the new exhaust manifold of the engine will be increased to 30.8 mm diameter from 32 mm (FIG. 5) to improve the performance of the engine power output.
The transmission 2.CVT
This model uses a new generation of CVT, model RE0F11A. For the past Dongfeng Nissan brand of low-emission vehicles, due to the limited installation space, can only match RE0F08B type CVT transmission, the maximum input torque of only 120 N m;? For large displacement cars need to match RE0F08A type CVT transmission, The maximum input torque of 150 N? m. Now, RE0F11A RE0F08B smaller volume ratio, which has reached the maximum input torque 150 N? M, and also increases the speed range (FIG. 6). Therefore RE0F11A can replace the previous paragraph 2 CVT, installed in any of a vehicle V platform. So, which the CVT transmission is how to achieve high torque small volume of it?
(1 ) auxiliary gear box
RE0F11A is the first time the auxiliary gear box in the world. the CVT (FIG. 7), which is by far the largest shift range. We know that, the larger torque is transmitted to CVT, the pulley belt contact region must be increased (FIG. 8), which means that CVT pulley must be large enough, but this will inevitably increase the size of the transmission. To solve this problem, RE0F11A using the auxiliary gear box to reduce the torque load carried by the pulley. Which utilizes a continuously variable CVT pulley characteristics, cover the sense of shifting auxiliary gear box, fully retained the specific CVT shift feeling. Practice has proved that as long as a reasonable match with the auxiliary pulley CVT gearbox torque proportion, is entirely achievable small torque shift.
speed ratio
is a conventional CVT continuously changes (FIG. 9The figure: n- engine speed, – K-speed ratio, the speed V-), the gear ratio of the automatic transmission is a step change (Figure 10). The auxiliary speed change process and the automatic transmission gearbox same row is achieved through the planetary gear to shift (FIG. 11). To achieve the effect of the shift from the generally conventional CVT, RE0F11A using reverse speed ratio change CVT pulley auxiliary gear box to compensate for the instantaneous gear shift ratio change (FIG. 12), so that the total gear ratio of the transmission is not mutated. Seen from the figure, the engine speed and the vehicle speed has not changed for shifting the auxiliary gearbox moment.
In order to avoid shift shock, the auxiliary instant gearbox shifting, the transmission control by the CVT input shaft torque remains unchanged, so that the engine speed will not jump. However, the inertia of the auxiliary gear is an objective of the output shaft torque used for this purpose in the auxiliary gearbox shifting moment, then resume the first embodiment to reduce the shift shock buffer (FIG. 13). Although this time will produce traction of the vehicle changes, but the use of the inertia of the vehicle itself, as long as the rate of change in the traction control is predetermined range (FIG. 14), the driver can feel the shift shock completely. For example, in a time shift, the amount of change of traction 0.03 N, is found by shifting the curve CVT, when traction slope of 0.1 N / s, as long as the length of time shifting the auxiliary gearbox control instant 0.3 s, the driver will not notice the shift. In this way, the driver of the vehicle will be exactly the same feeling with the conventional CVT.
(2) structural features
Moreover, paragraph CVT still many aspects to improve. In order to reduce oil agitation resistance of the transmission of rotation between the holding member and the transmission oil a certain distance (FIG. 15), measure alone can increase the percentage of 30 fuel economy. Due to the pulley size reduction reduces the overall quality of the transmission 13 percentage. With a slim type torque converter,The total length of the transmission 10 percentage shortened, which for front wheel drive vehicles, saving valuable space for installation. A torque converter lockup clutch buffer using low stiffness, so that more stable transmission. It also expanded the range of the lock-up clutch, and at a lower speed will enter the lock, to further improve fuel economy. Efficient transmission oil pump using the oil pump, the hydraulic pressure may be adjusted according to the conditions of the transmission. These nuances are all designers reflect increase awareness of energy saving. Auxiliary clutch gearbox made integrated shift control part, so that a more stable and reliable work.
(Liu Zhonglong, Hu Yong)