What Is a Load Limit?

Because of the functional relationship between speed and pitch, the best match can be guaranteed under design conditions. Therefore, when the running state of the host changes, it is difficult to ensure the best match. For example, if the load increases or the pitch increases, it may overload the host. If a load limiter is not used, the host operator needs to constantly monitor the machine load. Therefore, in order to avoid overload of the host and reduce the labor intensity of the operator, an automatic load limiter should be set in the operation of the automatic remote control system. ^[1]

The host speed control can not only consider the given target, but also take into account its control effect. Because, in the case of large-scale manipulation of the host or changing operating conditions, if only its control target is considered, the host may be overloaded for a short time in the dynamic process. Therefore, in order to ensure the operation safety of the host, once the load limit curve is touched in the control, the control program must abandon certain control indicators and perform load limit. ^[2]

The types of load limits and control methods are as follows:

(1)

The setting signal sent by the car clock is first sent to the acceleration load program limitation link to realize the acceleration limit and thermal load program limitation, so that the set speed of the car order is changed according to a predetermined change rule, so as to prevent the host from accelerating during the acceleration process. Excessive thermal load fluctuations at fast and high loads. Then, it is sent to the critical speed automatic avoidance link and the minimum and maximum speed limit links to ensure that the host does not operate in the critical speed range, and when the set speed is lower than the minimum stable speed, it is limited to the minimum stable speed. When the set speed is greater than the maximum allowable speed, it is limited to the maximum speed.

The setting signals restricted by the above links are led to the comparison section of the speed regulation section. The actual speed of the host is also detected by the speed detection section. The comparison section compares the two and the resulting deviation is adjusted according to the PID. Calculate, and then control the throttle opening of the host through the load limit and execution links to adjust the host speed to the set speed.

In the process of speed regulation, if the control output from the regulation calculation link is greater than the maximum allowable fuel supply amount given by the charge air pressure limit link, or greater than the maximum allowable fuel supply amount given by the torque limit link, or greater than the maximum load Value, the control system will select the smallest one as the output to limit the fuel supply of the host. In this case, the speed and accuracy indicators of the speed regulation system have declined, but the host's operating safety has been guaranteed. In some electronic governors, in order to make the speed regulation characteristics approach the ideal propeller propelling characteristics, a propeller characteristic limitation link is usually added after the PID regulation law calculation, or a nonlinear variable gain operation link is used. ^[2]