| 摘要 |
1,257,088. Measuring excavating rate. INSTITUT AVTOMATIKI. Aug. 19, 1969, No. 41342/69. Heading G1N. [Also in Division G3] The excavating rate of a rotary excavator having a belt conveyer for the excavated material is measured by measuring the load on the conveyer, the linear speed of the conveyer, and the inclination angle of the conveyer, and deriving therefrom a signal representing the excavating rate. A tachogenerator 2 and unit 3 generate an A. C. voltage of amplitude representative of the speed of the belt which is fed to the primary winding 29 of a differential transformer, the core 28 of which is displaced according to the weight of material on the belt. The A.C. signal from unit 3 is also fed to a rotary transformer 5 the coupling factor of which is a cosine function of the angle of the conveyer from the horizontal. The output of secondary windings 30, 31 is rectified at 32, 33 and the output from transformer 5 is rectified at 6 and subtracted from the output of rectifiers 32, 33 to give a D.C. signal corrected for the weight of the conveyer. Computing circuit 10, including a modulator 11 and a negative feedback loop comprising a further cosine rotary transformer 13 and demodulator 16 forms a signal proportional to the excavating rate, namely the product of the load and velocity. An indicator 20, recorder 23 and integrator 22 (for giving total rock excavated) are provided. A magnetic amplifier 21 controls pivoting of the rotor supporting boom to maintain the excavating rate at a preset level. |
