Reciprocating valve for a double piston concrete pump

Claim 1

A valving apparatus for interconnecting a double piston pump having two cylinders with conveying conduit means and with supply means comprising a valve housing having a given length, said housing further having a first pair of aligned ports for connecting said valve housing to said two pump cylinders, a second pair of aligned ports for connecting the valve housing to conveying conduit means, and a third pair of aligned ports for connecting the valve housing to said supply means, said ports being aligned at a pair of planes extending transverse to the longitudinal axis of said housing with each port of each pair of ports being aligned with a separate one of said planes, a piston valve plug mounted solely for axial movement in said valve housing, said piston valve plug having a central plug section with a cylindrical central passageway extending through the valve plug and the valve housing in a direction to interconnect ports of said first and second pair in a common plane, a first outer plug section with a first outer bent cylindrical passageway and a second outer plug section with a second outer bent cylindrical passageway, said first and second outer plug sections and said central plug section having together a length shorter than the length of the valve housing to permit the axial displacement of the piston valve plug in said housing, said first and second outer plug sections extending on each side of said central plug section, each of said first and second bent outer passageways including an angle within the range of about 75° to less than 90° in a direction to interconnect ports of said first and third pairs of ports in a common plane, said passageways being axially spaced, whereby in one axial position, said central passageway interconnects one port of said first pair with one port of said second pair, while one of said outer bent passageways interconnects the other of said first pair with one of said second pair, and whereby in another axial position said central passageway interconnects the other ports of said first and second pairs, while the other of said outer passageways interconnects said one of said first pair of ports with the other of said third pair of ports, and means operatively connected to said valve plug for axially moving said valve plug in said valve housing so as to be compatible with the function of suction, pressure and suction in that order for each work cycle of the valve, wherein said valve housing comprises plane walls defining a plug chamber, said piston valve plug also having plane walls fitting into said plug chamber, and wherein at least two of said plane walls of said plug chamber and at least two respective plane walls of said piston valve plug respectively include an angle of up to 75°.