Bus Technology and Research on Network Control System of Automotive Lighting and Signaling Devices Pan Xun\Zhang Lijun 2, Zhao Yunxia 2 (1. Mengshi Bus Co., Ltd., Zhengzhou 450004, China; 2. Zhengzhou Yutong Bus Co., Ltd., Zhengzhou 450061, China) The lighting and signaling devices are controlled, and all ECUs are connected to the network via twisted pairs to form a network control system for the automotive lighting and signaling devices, including topology, communication protocols, system control, and the like.
In the process, the function analysis of the whole vehicle lighting and signalling device was first carried out. According to the principle of regional autonomy, the development of autonomous future was delineated according to the principle of close geographical position, similar functions, basically consistent performance requirements and the former. 12ChinaAeademielQumalEleetroniePubli area. Based on this, we divided the automotive electrical appliances into the following four areas: i left auto electrical appliances and electronic control systems have become the fourth most important part of the car after the engine, chassis and body. In some high-end cars, it includes power equipment (generators, batteries), starters, ignition systems, DC motors (wiper motors, heater motors, oil pumps, electric window and door motors, mirror motors, etc.), lighting and Signal devices, car instruments, car audio systems, air conditioning devices, etc., also include ESA alarm systems, traffic guidance systems, and some comfort and convenience devices. According to statistics, in order to achieve the purpose of centralized control, the control line is shuttled several times between the equipment installation point and the cab. According to the traditional wiring method, the length of the wire is about 2km, the number of electrical nodes is as high as 1,500, and the above figures are about every 10 times the age, this will bring the following four major drawbacks: 1 occupying the precious space of the car; 2 a large number of electrical contacts often fail due to poor contact, work reliability is reduced; 3 for maintenance, repair Work has brought great disadvantages; 4 many resources, especially sensor resources, have not been fully utilized and are wasted. The best way to solve these problems is to adopt network technology. In foreign countries, this work has been carried out relatively early, and a variety of automotive electrical networks, such as ABDS, CAN, CCD, VAN, etc., have been developed. Domestic research in this field is still in its infancy. Using network technology, it is estimated that the electrical wiring can be reduced by more than 80%, saving space, reducing the quality of the car, adding the reliability of the automotive electrical system, facilitating maintenance, without the addition of new sensors and actuators, the overall performance is Optimization, so that the operation is coordinated and unified, easy to realize automation and intelligence, there is huge potential in the overall performance optimization control of the automobile. It is the automotive electronic technology. The automotive electrical network can be divided into control-oriented network (CON) and information-oriented transmission. Network (ION). According to the classification of the Society of Automotive Engineers (SAE), the network speed is divided into three categories: A, B, and C. Class A is a low-speed network with a baud rate below 9 600 bps. The baud rate is below 125 kbps for medium-speed network B. Above 125kbps is a high-speed network class C. This paper uses network technology to construct a low-speed system for automotive lighting and signal-oriented control, which fills the gap in the field of automotive network control.
1 Topical structure network Automotive electrical appliances have two technical support, one is the micro-mechanization of electrical units or regional electrical appliances, and the other is network technology. An electrical unit is the smallest electrical component or device that has a single independent function and can be installed separately, such as switches, contactors, relays, signal lights, and the like. A regional electrical appliance refers to a collection of electrical appliances that are close to each other, function related to each other, or have a certain logical relationship, such as a front combination lamp, a rear combination lamp, and the like. It is equipped with a single-chip microcomputer to form an ECU, which accepts the command of the host computer and controls the electrical work of the area under its jurisdiction. This process is called computerization of unit appliances or regional appliances. The use of communication lines and power lines to connect these computerized unit or regional appliances into a network is called network.
The front area is mainly responsible for the control of the left front illumination of the vehicle, the low beam, the low beam and the turn signal; the right front area is mainly responsible for the control of the right front illumination of the vehicle, the low beam, the low beam and the turn signal; the left rear area is mainly responsible for Rear left rear lighting backlight, brake and turn signal lights, license plate light control; right rear area is mainly responsible for vehicle right rear lighting reversing light, brake and turn signal lights, rear fog light control (left rear and right rear) The zone steering is combined with the brake light into a light, and the flasher is cancelled, and the corresponding control of the light during steering and braking is implemented by software. At the same time, the original driver's various control keys are changed into the control area. * It is responsible for accepting, checking and executing various control actions of the driver. The original instrument area is changed into the display area. One is responsible for displaying various functions and fault display. .
Secondly, the regional computerization work is carried out. Except that the control area and the display area share one ECU to form the upper computer, each of the other areas applies an ECU for self-control, and each of the lower computers accepts the control of the upper computer.
According to the above division method, except that the upper computer uses an 8051 single-chip microcomputer as the core ECU, the other four regions use one topology structure different from each other. The upper computer uses the 8051 chip, and the lower computer uses the 8051 chip. It is a 2051 chip, and the upper computer has two parts of a control area and a display area, wherein the control area accepts various control commands of the driver, and changes to an electrical signal recognizable by the 8051 through the electromechanical conversion device, and passes the instructions through the upper computer. After compilation, it is transmitted to the bus via the serial communication interface; the function of the display area is to display the working status of the electrical appliances in each area, and display the fault information of the equipment. The ECU of the 2051 single-chip microcomputer controls the network characteristics of each electrical appliance in the jurisdiction. Since the functional similarity is taken into account when dividing the area, in fact, the four areas of the left front area, the right front area, the left rear area and the right rear area have basically the same ECU structure and function, but only slightly different in software function. This greatly reduces the amount of development work.
After completing the above work, the ECUs are connected by power lines and twisted pairs to form a low-speed network system for automotive electrical appliances. The low-speed network of automotive electrical appliances is formed by shielding the twisted-pair wires according to the above-mentioned topological structure. The internet. The so-called low speed means that the baud rate of the network is below 9600 bps, and the controlled electrical appliances are common lighting and signal devices for automobiles, such as high beam lights, low beam lights, turn signals, brake lights, license plate lights, front and rear fog lights, etc. These are the characteristics of the response speed is not too high, that is, the so-called real-time requirements do not take into account the characteristics of the low-speed control of the electrical appliances, the development of automotive lighting and automotive appliances. Nevertheless, the response speed of the system is still the topology of the millisecond 1994-20 network 1 network control system, aw * K), where Vc is the speed of the passenger car relative airflow (m / s); for the car body insulation material thickness ( m), An is the heat transfer coefficient of the car body insulation material W / (m2 * should also consider the passenger car rating requirements when calculating W2.
Table 1 Calculation results of heaters matched by a passenger car 6120 passenger car Model engine parameters calibration power / speed (kW / (r / engine mass (kg) coolant mass (kg) maximum speed (km / h) car eve: long X width X height (m) bus parameters inside the car: length X width X height (m) external heat dissipation area (m2) internal heat dissipation area (m2) glass area (m2) inside and outside maximum temperature difference (K) calculation heating time (min) result The heater heat power (kW) is actually matched to the heater heat power (kW). Kl represents the heat transfer coefficient corresponding to the heat dissipation due to the air leakage of the passenger compartment. Kl=(0.20.6) Ko. The heater can be determined from the above relationship. Example of Heat Power W2.3 Heater Power Determination According to the above calculation relationship, the heater heat power matching with the passenger car can be determined. Table 1 lists the calculation results of the heaters that should be matched to a 6120 passenger car using the above relationship. The calculation shows that the car can match the liquid fuel heater with 30kW thermal power in our existing products, which can fully meet the requirements of use. The current matching heater thermal power is too large.
4 Conclusion The proposed method for calculating the fuel heater matching of passenger cars in this paper is consistent with the results of the empirical calculation formula provided by Eberschbach AG in Germany, which can provide guidance for the assembly of fuel heaters for passenger cars.
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