| 摘要 |
1,201,775. Mixing apparatus. CRANE FRUEHAUF TRAILERS Ltd. 20 Sept., 1967 [24 Oct., 1966], No. 42748/67. Heading B1C. [Also in Divisions F1, F4 and H2] Apparatus for mixing two constituents from tanks 20, 22 for making plastic foam has controls for maintaining a constant flow rate of each constituent from a pump, in spite of variations in line pressure. As described, the mixture is supplied to insulate a cavity 14 in a vehicle body through a pipe 64 which is withdrawn gradually by rollers 66, the mixture entering the pipe within a housing 70. The pipe is slit within the housing and therefore reduces in effective length as it is withdrawn, causing a reduction in pressure loss through the pipe. The pressures in the lines 38, 40 from the tanks are maintained constant by controls 46, 52 for electric motors 44, 50 driving separate pumps 34, 36 for the constituents. The control (Fig. 5, not shown) senses the armature current and varies the armature voltage to give a voltage which increases with increasing load, to compensate for pump slip, and therefore provides a constant flow rate. The flow rates may alternatively be controlled by modifying the characteristics of the pumps or of the lines from them, and the line pressure may be sensed instead of the motor current. |
