| 摘要 |
The invention relates to a sequential control system for two-cylinder thick medium pumps whose delivery cylinders (1, 1') are actuated hydraulically by two drive cylinders (5, 5') in opposing cycles. A pipe shunt (3) is provided inside a material feed container and is connected at the inlet side alternatively to the apertures (2, 2') of the delivery cylinders (1, 1') and at the outlet side to a pump line (4). The drive cylinders (5, 5') are each connected at one end to a different connection pint of a reversing pump (6) to form a closed hydraulic circuit (11, 11') and at their outer ends via an oscillating oil line (12) hydraulically to one another. To effect switching of the pipe shunt (3), pressure oil is taken off directly from the hydraulic lines (11, 11') leading from the reversing pump (6) to the drive cylinders (5, 5'). To ensure smooth switching of the pipe shunt (3) without any malfunctioning in delivery operation, the invention proposes that the reversing pump (6) should be switched by reversing the flow and the pipe shunt (3) if the pistons (8, 8') of the drive cylinder (5, 5') reach their end position; and the oscillating oil line (12) should be closed off at least for time during switching of the reversing pump (6).
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