Patent ID: 7104057
Filing Date: 2006-09-12
Classification: F04B

Abstract:
1. A concrete transfer system of a concrete pump car which comprises; a pair of concrete input tubes mounted to a pair of holes in the inside surface of a hopper, first and second drive cylinders mounted in communication with the concrete input tubes for sucking and transferring the concrete by forward and backward movements of pressure pistons having rod ends, an oil pressure pump for supplying a fluid to the first and second drive cylinders, a respective rod sensor for sensing the movement of the rods of each of the first and second drive cylinders, a control unit for receiving a sensing signal from each rod sensor and producing a control signal, an oil path change drive unit for supplying selectively the fluid from the oil pressure pump to the first and second drive cylinders according to a control signal from the control unit, the concrete transfer system of the concrete pump car comprising: a first logic valve in which a first oil pressure line connected to one side of the oil pressure pump is connected to an input side of a main spool, the output side of the main spool being in communication with a rod side of the second drive cylinder by the medium of a third oil pressure line; a second logic valve in which an input side of a main spool is connected to the first oil pressure line, thereby connecting the second logic valve in parallel to the first logic valve, the output side of the main spool being in communication with a piston side of the first drive cylinder by the medium of a fourth oil pressure line; a third logic valve in which an input side of a main spool is connected to a second oil pressure line connected to the other side of the oil pressure pump, the output side of the main spool being in communication with a rod side of the first drive cylinder by the medium of a fifth oil pressure line; a fourth logic valve in which an input side of a main spool is connected to the second oil pressure line, thereby connecting the fourth logic valve in parallel to the third logic valve, the output side of the main spool being in communication with a piston side of the second drive cylinder by the medium of a sixth oil pressure line; a reverse currently preventive device having an input port installed on the first and second oil pressure lines for preventing a reverse current for generating to the oil pressure pump and output ports are connected with each other; a high/low pressure selection valve having a supply port connected to an output port of the reverse current preventive device, a first work port combined with an oil pressure line, which is selectively communicated to the supply port and connected to control spool sides of the second and fourth logic valves, a second work port combined with an oil pressure line, which is selectively communicated to the supply port and connected to control spool sides of the first and third logic valves, and a discharge port selectively communicated to the first and second work ports; a fifth logic valve in which a control spool side is connected to the first work port of the high/low pressure selection valve, a discharge side of the main spool is connected to the third oil pressure line and the input side of the main spool is connected to the fifth oil pressure line; and a sixth logic valve in which a control spool side is connected to the second work port of the high/low pressure selection valve, a discharge side of the main spool is connected to the fourth oil pressure line and the input side of the main spool is connected to the sixth oil pressure line.