The cruise control system is an automatic vehicle driving device that enables the automobile to operate within the favorable range of the engine, reduces the driver's driving and labor intensity, and improves driving comfort. The cruise control system in English is the cruise control system, abbreviated as CCS. The cruise control system is also known as a cruise travel device, a speed control system, a constant speed travel system or a cruise control system.
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The cruise control system has been widely used since it was first applied in the United States in 1961. The over-the-air control system is installed on most cars in the United States. The proportion of cruise control systems for cars installed in Japan and Europe is also increasing. The Audi A6, Shanghai Volkswagen Passat and Guangzhou Honda Accord produced by FAW-Volkswagen also installed a cruise control system.
In the continental countries, there are many opportunities for driving long-distance driving. When driving on the highway for a long time, after opening the automatic control switch of the system, the cruise control system will automatically increase or decrease the throttle opening according to the driving resistance, so that the car The driving speed is kept constant. And it can prevent the driver from stepping on the accelerator pedal frequently, and ensure that the car runs at a preset speed. The car runs at a constant speed under certain conditions, greatly reducing the fatigue strength of the driver. Since the cruise control system can automatically maintain the vehicle speed, unnecessary man-made changes in the accelerator pedal are avoided, thereby improving the fuel economy of the vehicle and the engine emissions.
First, the function of the cruise control system
(1) Basic functions
1. Speed ​​setting. When the vehicle speed setting switch is pressed, the traveling speed for that time can be stored and the speed can be maintained.
2. Eliminate functionality. When the brake pedal is depressed, the above functions disappear immediately. However, the above setting speed continues to be stored.
3. Recovery function. When the recovery switch is pressed, the original stored speed can be restored.
In addition to the above three basic functions, the following functions can be added if needed:
1. Slide. Press and hold the switch to decelerate and cruise at the speed at which the switch leaves the switch.
2. Accelerate. Press and hold the switch to accelerate, and enter the cruise without the speed of the switch.
3. The speed fine adjustment is raised. During cruising speed travel, the vehicle speed is slightly increased when the steering switch is switched from ON to OFF.
(2) Fault insurance function
1. Low speed automatic elimination function. When the vehicle speed is less than 40km/h, the stored vehicle speed disappears and the speed cannot be restored.
2. Brake pedal elimination function. Two switches are mounted on the brake pedal, one for signal cancellation of the ECU and the other to directly stop the actuator operation.
3. Various elimination switches. In addition to the brake pedal cancellation function, there are also functions for eliminating the operation of the parking brake, clutch (M/T), and speed control lever (A/T).
Second, the advantages of the cruise control system
(1) Improve the driving comfort of the car
Especially in the suburbs or on the highway, this superiority is more remarkable. In addition, when the car is driven at a certain speed, the burden on the driver is reduced, making it easy to drive.
(2) Saving fuel, having certain economic and environmental protection
Under the same driving conditions, the use of a cruise control system can save 15% of fuel for an experienced driver. This is because after using the system, the fuel supply between the vehicle and the engine power can be optimally matched, and the exhaust gas emissions are reduced.
(3) Maintaining the stability of the car speed
Whether the car is driving on an uphill, downhill or flat road, or driving at a wind speed, the speed of the car will remain the same as long as the engine power is allowed.
Third, the structure of the cruise control system
The cruise control system consists of sensors, operating switches, actuators, and cruise control ECUs. The sensors and switches feed the signals to the cruise control ECU. The ECU calculates the opening of the throttle based on these signals and signals the actuator to automatically adjust the throttle opening.
(1) Operation switch
The operation switch is mainly used to set the cruising speed or reset it to another speed, and cancel the cruise control. It mainly includes the main switch, control switch and exit cruise switch.
1. Main switch. The main switch (MAIN) is the main power switch of the cruise control system. Most of them adopt the button mode. Each time they are pushed in, the power of the system is turned on or off. The main switch remains closed even if the ignition is switched back on.
2. Control the switch. The joystick control switch has five control functions: SET, COAST, RES, ACC, and CANEL. The SET and COAST modes share one switch, and the RES and ACC modes share another switch. When the switch is operated in the direction of the arrow, the switch is turned on; when it is released, it is turned off. This is an automatic return type switch.
3. Exit the cruise control switch. The exit cruise control switch includes a cancel switch, a stop light switch, a parking brake switch, and a clutch switch to open the neutral switch. When one of the switches is turned on, the cruise control will be automatically cancelled. However, when the speed of the CCS cancellation is more than 35km/h, the speed is believed to be in the cruise control ECU. When the RES switch is turned on, the last stored speed will be automatically restored.
4. Parking brake switch. When the parking brake lever is pulled up, the switch is turned on, the cancel signal is transmitted to the cruise control ECU, and the parking brake indicator light is on.
5. Neutral start switch. When the shift lever is set in the P or N position of the automatic transmission, the switch is turned on, and the cancel signal is transmitted to the cruise control ECU.
6. Clutch switch. When the clutch pedal is depressed, the switch is turned on, and the cancel signal is transmitted to the cruise control ECU.
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(two) sensor
1. Vehicle speed sensor. It is used to provide an alternating oscillation pulse signal proportional to the actual vehicle speed, and the cruise control ECU processes the signal. The vehicle speed sensor is shared with the engine electronic control system.
2. Throttle position sensor. Its function is to provide the cruise control ECU with a signal proportional to the throttle position (opening), which is shared with the engine electronic control system.
3. Throttle control rocker sensor. Most of the slide line potentiometers are used. When the throttle control rocker rotates, the potentiometer rotates to output an electrical signal that is proportional to the position of the control rocker and continuously changes.
(three) cruise control ECU
The cruise control ECU is composed of a processor chip, an A/D, a D/A conversion IC, and an output reset drive and protection circuit. The ECU receives signals from the vehicle speed sensor and various switches and processes them according to the stored program. When the vehicle speed deviates from the set cruise speed, the actuator is given an electric signal to control the action of the actuator so that the actual vehicle speed is consistent with the set vehicle speed.
When the car is in the cruise control state, generally when the vehicle speed is lower than 40km/h, the ECU will cancel the cruise control, so that the cruise control does not work when the car is braking or turning. When the vehicle speed exceeds the set speed of 68km/h, the ECU cancels the cruise control; when the deceleration of the car is greater than 2m/s2, and the brake light switch action of the car, the ECU also automatically cancels the cruise control to ensure driving. Safety.
(four) actuator
The actuator converts the current or voltage signal output by the ECU into mechanical motion, thereby controlling the opening of the throttle valve, and finally achieving the purpose of controlling the vehicle speed. There are two types of actuators currently in use, one is vacuum driven and the other is motor driven. The former is operated by a negative pressure throttle, and the latter is operated by a micromotor.
Fourth, the use of cruise control system considerations
The following problems should be noted in the use of the cruise control system:
1. In order to get the best control of the car, do not use the cruise control system when encountering traffic jams or driving on wet roads such as rain, ice, snow, etc., or when encountering windy weather.
2. In order to avoid misoperation of the cruise control system, when the cruise control system is not used, the control switch of the cruise control system must be turned off.
3. When the car is driving on a steep slope, using the cruise control system will cause excessive engine speed changes, so it is best not to use the cruise control system. Avoid driving when driving downhill. If the actual running speed of the vehicle is much higher than the set vehicle speed, the cruise control device can be omitted, then the transmission can be shifted to the low gear, and the vehicle speed can be controlled by the engine brake.
4. When the car is cruising, the car equipped with the manual transmission should not be placed in the neutral position when the clutch pedal is not depressed, otherwise the engine speed will rise sharply.
5. Use the cruise control system to pay attention to observe whether the CRUISE indicator light on the instrument panel is shining. If it is flashing, it indicates that the cruise control system is in a fault state. When the system is found to be faulty, stop using the cruise control system and use the cruise control after troubleshooting.
6. ECU is the backbone of the cruise control system, sensitive to electromagnetic environment, humidity and mechanical vibration. When using, pay attention to moisture, vibration, magnetic and pollution.
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