И инновации современной
Determination of the level of increase in the power of
жүктеу/скачать 6,6 Mb. Pdf көрінісі
|
статья
| Determination of the level of increase in the power of
mechanical losses of the ICE, to ensures the effective service braking of the vehicle by ICE First, let us determine the amount of deacceleration, in which the vehicle braking by the engine is effective. The vehicle's ICE braking system belongs to the auxiliary braking system, but under certain conditions it may also belong to the spare braking system. The auxiliary braking system can be used either separately or together with the service braking system. On vehicles with a higher weight, to improve downhill braking efficiency, the car's auxiliary braking system is equipped with a motor brake, a flap that blocks the 39 exhaust pipe. According to GOST 33997-2016 [11] an auxiliary brake system without a motor brake is checked in road conditions by actuating it and measuring the car deceleration when braking in the speed range of 25-35 km/h. In this case, a gear must be engaged in the transmission, which excludes exceeding the maximum permissible engine crankshaft speed. Auxiliary braking system is considered to have withstood the test of braking efficiency if it provides steady-state deceleration of at least 0.5 m/s2 for the car with the permitted maximum weight and 0.8 m/s2 for the car with the driver in rigged condition. The spare brake system is designed for use in case of failure or malfunction of the service brake system. It can be half as efficient as the service braking system, e.g. it can function as one of the circuits in the service dual circuit brake system or as a parking brake system. However, the latter must provide proportionality between the pedal force (lever) and braking torque on the wheels of the car. This requirement is often not satisfied, for example, the parking brake system of cars, which is controlled by a lever, in some cases, it does not provide a smooth, adequate control of the deceleration of the car in proportion to the force of the driver to the control. An engine in vehicle with transmission also does not meet the GOST requirements for a spare brake system. However, it will satisfy them if the car is equipped with a variator, the gear ratio of which the driver can smoothly change using a pedal or lever. Norms of braking efficiency of the car with the help of the spare brake system during the tests on the stands as well as in road conditions are given in Table 3 and Table 4, respectively. Table 3 – Norms of car braking efficiency by means of a spare braking system during stand tests Type of transport vehicle Vehicle's category Effort on the control unit, H Specific braking force, at least Passenger and cargo- passenger vehicles М 1 686 (589*) 0.26 М 1 , М 2 686 (589*) 0.23 Trucks N 1 , N 2 , N 3 686 (589*) 0.23 * For vehicles with manual control of the spare brake system. 40 Table 4 – Norms of car braking efficiency by means of a spare braking system during inspections in road conditions. Initial braking speed – 40 km/h Type of transport vehicle Vehicle's category Effort on the control unit, H Stepped deceleration, m/s 2 , at least Braking system response time, s, max. Passenger and cargo- passenger vehicles М 1 490 (392*) 2.60 0.6 М 1 , М 2 686 (589*) 2.25 0.8 (1.0**) Trucks N 1 , N 2 , N 3 686 (589*) 2.25 0.8 (1.0**) * For vehicles with manual control of the spare brake system. ** For vehicles made before 01.01.81. To determine the conformity of the efficiency of braking of a modern passenger car with the requirements of GOST, we use the calculated dependencies of the car deceleration in different gears on the speed of braking during the braking process. When vehicle is braked by the engine, its slowdown is caused by three forces and is determined by the formula on a horizontal road section: жүктеу/скачать 6,6 Mb. Достарыңызбен бөлісу:
|