초록 ▼

A directional control valve having three positions controls the direction of flow through an asphalt distributor. The directional control valve is interposed between a pump and a feed line assembly to a spray bar. The directional control valve has a first position in which flow is recirculated throu

A directional control valve having three positions controls the direction of flow through an asphalt distributor. The directional control valve is interposed between a pump and a feed line assembly to a spray bar. The directional control valve has a first position in which flow is recirculated through the pump, a second position in which flow is delivered to the spray bar and a third position providing for handspray and transfer operations. A pressure relief valve is provided for controlling return flow of asphalt from the spray bar to the tank. The pressure relief valve is open in spray bar circulation mode and is closed during a spraying mode. According to the preferred embodiment the directional valve and pressure relief valve are contained within a modular control valve assembly. The directional control valve eliminates the need to reverse the flow in one of the individual feed lines and feed line assembly connecting the modular control valve assembly to the spray bar. The feed line assembly includes a delivery and return line running coaxial or otherwise adjacent for heat transfer therebetween. The directional control valve reduces the quantity and lengths of exposed valving and plumbing associated with prior asphalt distributors.

대표청구항 ▼

1. An apparatus for controlling the flow of liquid asphalt in an asphalt distributor, the asphalt distributor having a tank, a pump connected to the tank, and a spray bar, comprising:a directional control valve having an inlet, at least two outlets, and at least three positions, the inlet connected

1. An apparatus for controlling the flow of liquid asphalt in an asphalt distributor, the asphalt distributor having a tank, a pump connected to the tank, and a spray bar, comprising:a directional control valve having an inlet, at least two outlets, and at least three positions, the inlet connected to said pump, said at least two outlets including a first outlet connected to the tank and a second outlet connected to the spray bar, the directional control valve having a first position connecting the inlet to the first outlet, a second position connecting the inlet to the second outlet, and a third position disconnecting the inlet from the first and second outlets; and means in operational communication with the directional control valve for selectively controlling the position of the directional control valve.