ZF6 automatic transmission fuel economy and contribution to environmental protection
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1 rumors Since the decision to develop a six-speed automatic transmission in 2001, it is an obvious fact that the transmission should be the next-generation transmission to replace the 4-speed and 5-speed automatic transmissions. In addition to the new features and functions, the main goal of the new transmission is to improve fuel consumption and acceleration. Compared with their predecessors, the 6-speed transmission can meet both requirements without increasing the weight and size. The goal of a complete range of transmissions and the improvement of efficiency and emissions with them will be launched soon.
For the new turbocharged diesel engine developed in Europe, the engine torque has increased significantly, so the range of its product range must be considered when developing a new transmission. The MyTronic series first introduced the 6HP26, the engine torque was 600Nm, then the 6HP32 with a torque of 750Nm, and the 6HP19 designed to face the high-volume mid-size car market with a torque of 400Nm. Since all models have the same transmission The Lepelletier gear train allows the design of the three transmissions to have a significant number of common and similar components, which helps reduce engineering and production costs.
2 Environmental Review In order to improve the environmental characteristics of the transmission, development engineers can contribute in many ways. From the concept of the transmission, the design of the shaft and gear must be very careful and use different materials and manufacturing processes. Here are some of the main goals: better fuel consumption and lower emissions and consumer driving conditions. Longer lifespans. Lifetime lubricants reduce weight and reduce manufacturing time. Prohibit the use of prohibited materials to limit the use of synthetic materials. In addition to the above-mentioned direct and transmission-related projects, the refurbishment must also improve the entire development and manufacturing process to conserve energy and resources throughout the life of the transmission.
3 Product Specifications Since the output torque of the 6, 8, and 12-cylinder engines is still increasing (especially for diesel engines), careful market research has been conducted before determining the input torque of each transmission. Comparing the previous 5-speed transmission, on the one hand, it is necessary to increase the maximum torque, on the other hand, it is necessary to cover the torque range with a transmission. In order to optimize the product to suit all kinds of cars, three transmissions based on the same gear structure were developed.
6HP19 applies torque 6HP32 for torque to optimize the power-to-weight ratio of each product, using modular torque converters, gears and clutches.
All of these transmissions can be an all-wheel drive system with the Torsen differential. The transmission can also be fitted with a 4X 4 splitter, while the transmission fully meets the 4X4SUV powertrain.
A transmission design uses all the same gear trains for all three transmissions, provided these transmissions have a high degree of common components. The wheel train has three rows of planet wheels (one single wheel train and one Ravi wheel train) and five shift actuators. The multi-function shifting actuator is used at different gear positions, with 6 well-defined gear positions and a large speed ratio of 6.04 ().
The first was the 6HP26, which began in September 2001, and then the 6HP32, which was introduced in mid-2002. Then the 6HP19 was implemented in 2003. The transmission structure, control unit layout and component design are partially identical, at least very similar, so the development time overlaps. Much collaboration in development and product planning can reduce engineering time and resources in all aspects. Especially in the development phase, the conclusion of the introduction of functional and component tests saves test equipment and energy. The durability test of 6HP26 and 6HP32 was introduced into 6HP19. Due to the highest similarity of these transmissions, it is important that the development of their weight and quality characteristics exceeds expectations.
All transmissions have similar design features, such as oil pumps, trains, oil sumps and output components, as well as many components used on the 6HP19 and 6HP32 and 6HP26 components are one of the main ones that have been implemented. The goal is to use the same hydraulic control unit and 32-bit controller for all types of transmissions. With modern mechatronic modules, the control unit can be adapted to 4X2 and 4X4 transmissions respectively. This not only reduces investment and processing costs, but the same control unit ensures the same basic control and software functions for all transmissions. Engineering work can therefore be concentrated on the basic control system, and all transmissions have optional features such as: line-controlled shifting neutral idling control lock-up clutch slip control strategy fault-shifting strategy software as described in Section 2 There are a variety of measures at the end of the product that help/improve environmental protection, such as: transmission weight and size, transmission life, reduced parts, and the possibility of recycling. 5.1 Fuel economy and emissions from European automotive manufacturers' emissions targets in 2007 It can be seen that every component of the vehicle must contribute to achieving this goal. Previous studies have shown that higher speed ratios and smaller speed ratios can significantly reduce fuel consumption. The problem is that a new transmission structure that does not increase the number of trains and axles must be found, as this will increase the benefits of the internal losses of the transmission to offset the speed ratio. The Lepelletier wheel train increases both the speed ratio and the number of transmission components. In addition, there are the following features: Reduced oil pump viscosity, low viscosity, neutral speed, idle speed control, low torque, and all gears, the torque converter locks the transmission components and lubrication to achieve optimum transmission loss and 5-speed transmission. Can save at least 5% fuel consumption. Fuel saving can be 10% or more () under certain conditions.
For the fuel economy-focused powertrain, the acceleration is increased by 8% under the two parameters “Starting distance after 4 seconds†and “0-60 mph acceleration time.†5.2 Transmission weight and size when using 6 gears When the transmission replaces the 5-speed transmission, the size of the transmission must be optimized. That is, a balance is achieved between the same component and one of the lightweight designs. However, the prerequisite is that the requirements for installation by different users must first be met. Compared to the previous generation transmission, the 6HP19 has a 20% increase in power-to-weight ratio, while the 6HP26 is 30% and the 6HP32 is 60% ().
Not only does the transmission structure help reduce weight and size, but the testing and analysis of vehicle load also provides the possibility of reducing shaft and gear size. Especially at higher torque ranges, the data shows that the transmission is subject to very limited engine torque. Therefore, the 6HP32 weight loss is the most compared to the 5HP30.
Finally, design and material selection also contribute to fuel economy oils.
The transmission has an integral housing. The wall thickness using pressure casting is reduced to 3.5mm. The 6-speed transmission series is fitted with a plastic oil sump and an integrated filter. Compared with the steel sump and the independent filter, the weight is reduced by 40%. Although the 6HP19 and 5HP19 have the same length, the 6HP26 is shortened by 50mm compared with the 5-speed transmission, and the 6HP32 丨J is shortened by 100mm. 5.3 Transmission life There are two problems with the life of the transmission when it comes to environmental protection.
One is service and maintenance during the life cycle, and the other is the life of the repair and transmission.
Since 1992, the use of full-life lubricants in ZF's automatic transmissions has been very fashionable, so the new low-viscosity grades of the first-round coefficient of 0 oil-shell oil must also meet this goal. Even gears and bearings that have higher requirements for friction performance and reliability do not need to change the lubricant. Therefore, the ZF6 automatic transmission does not require any service for the lubricating oil during the life cycle.
Under the new load cycle strategy, simulation and calculation methods have been improved to achieve a more accurate transmission durability design. Through a large number of bench tests and loading tests, the transmission life span has been extended from 150,000 km to 150,000 miles for mid-size cars, so the replacement and repair of the transmission has been reduced.
5.4 Another contribution of the transmission component in addition to weight reduction is the saving of resources. Reducing the number of components in the transmission helps reduce the processing costs of the components. Compared to the 5-speed transmission, the 6-speed transmission gear mechanism has the advantage of reducing the number of axles and combining the Ravigne gear train.
Since 1996, all ZF new transmissions have been characterized by simultaneous shifting in all gear positions, eliminating the need for a one-way clutch. Table 1 compares the trains, clutches, and one-way clutches of the various ZF transmissions.
Table 1 The coefficient of the wheel and the clutch adopt the design strategy of integrating the function on a single component, the number of parts is reduced by 30%. Through various measures, simple parts such as bolts and electrical appliances and complex parts such as pipelines are reduced. Plate and clutch housing, etc. The extensive use of thin-plate material components helps to reduce the 1BC clutch housing. With the parallel engineering support of product planning and manufacturing, the welding design of the two components is changed to one component, such as combining two splines. After deep drawing and rolling, the part is finished in one process and then welded to the sun gear shaft without additional processing.
Speed ​​sensors, position switches and 32-bit controllers are integrated in the electromechanical module. A large number of internal and external harnesses and connectors can be reduced. It also brings huge benefits to automakers because it also reduces the number of harnesses and connectors inside the vehicle (2).
2 Control unit and electromechanical module 3 are the number of parts reduced compared with the 5-speed transmission. The main part is on the mechanical parts of the transmission, but it is also reduced by 20% when designing the hydraulic system. This is through the hydraulic and electronic components. It is integrated with the motor module on one valve body and one intermediate plate.
* As the 6HP26 is the first product to enter the market, there must be as many components as possible for other transmissions. Table 2 shows the number of common parts, and about 30% of the 6HP26 parts are available for 6HP19 and 6HP32 (Table 2).
The common components of Table 2 use different engines and a modular torque converter must be provided to fully satisfy the required torque converter matching characteristics and damping system. Start-up sensation, powertrain vibration, acceleration, and fuel consumption are all directly affected by the torque converter. This variable is therefore very sensitive from the perspective of the car manufacturer, as all of these parameters are related to driving comfort.
The various torque converters shown in Figure 4 have different characteristics and damping systems, and the locking strategy is adjusted for each engine, while fuel consumption and acceleration are also optimized. The W255 and W270 torque converters are newly developed. Through simulation, the damping system can be pre-selected for different engines and the hardware can be fine-tuned during development, so powertrain vibration can be avoided. Since the lock-up clutch can be locked at low engine speed and all gear positions, fuel consumption is saved.
5.5 Materials and Recycling As recycling becomes more and more important, the number of steel and aluminum alloy components in modern transmissions should increase.
In the 6HP series transmissions, the number of composite materials (such as pistons with rubber sealing lips) is significantly reduced, giving up the environmentally influential machining process. As a result, the ability to reuse is improved.
Due to the reduced weight, aluminum and steel components are reduced, and these materials account for 88% of the total weight of the transmission. 5 Material ratio The material of the plastic oil sump is polyamide 6.6 which can be recycled separately. The components of the 6-speed automatic transmission comply with the regulations prohibiting the use of lead, mercury, and cadmium, which is the EU Directive accessory that came into effect on July 1, 2003. Further, new coatings or anti-corrosion materials for hexavalent chromium will be put into use next year.
6 Conclusion The Tronic series consists of three types of transmissions, providing an almost optimal device for the vehicle. Transmissions with integrated or all-wheel drive capability are available for a variety of powertrain and engine installations. The high fuel economy, lightweight design and versatile components make the 6-speed transmission range environmentally friendly in all aspects of product design, production and vehicle use.
The high level of shifting quality combined with proven technology such as reliable wire-controlled shifting, the transmission shows the most modern technology. ZF will provide the first-class transmission for new cars in the next few years. To meet the more demanding fuel economy requirements, ZF improves the mechanical damping of the torque converter. The lock-up clutch can be locked under any operating conditions to ensure further reduction of fuel consumption in the 6-speed transmission series, ie at least another 3% reduction. In order to expand the range of use of the transmission, particularly in the field of diesel engines, the torque characteristics of the various transmissions are increased. Another goal is to improve shift time and shift response to provide a true dynamic motion standard choice. The “refurbishment†of the 6-speed transmission series is underway and will be the future choice; and it can be confirmed that the 6-speed automatic transmission technology will be the benchmark for the transmission industry in the next few years.
