Method and apparatus for avoiding or ameliorating cavitation in an asphalt cement fluid circuit

Abstract

A system for dispensing asphalt cement in connection with a working operation on a roadway includes a storage tank for asphalt cement and a working machine having a spray assembly for dispensing the asphalt cement. The system also includes a fluid circuit including a pump that is adapted to pump the asphalt cement from the storage tank to the spray assembly. A controller is operatively connected to the pump and is adapted to control the operation of the pump. A cavitation sensor is provided in the fluid circuit. The cavitation sensor is operatively connected to the controller and is adapted to transmit a cavitation signal to the controller when the cavitation sensor detects conditions in the fluid circuit that are indicative of the existence of cavitation in the pump.

What is claimed is: 
     
         1 . A system for dispensing asphalt cement in connection with a working operation on a roadway, said system comprising:
 (a) a storage tank for asphalt cement;   (b) a working machine comprising a spray assembly for dispensing the asphalt cement;   (c) an asphalt cement fluid circuit including a pump having a suction side, said pump being adapted to pump the asphalt cement from the storage tank to the spray assembly;   (d) a controller that is operatively connected to the pump and is adapted to control the operation of the pump;   (e) a cavitation sensor that is provided in the asphalt cement fluid circuit, said cavitation sensor being operatively connected to the controller and being adapted to transmit a cavitation signal to the controller when the cavitation sensor detects conditions in the asphalt cement fluid circuit that are indicative of the existence of cavitation in the pump.   
     
     
         2 . The system of  claim 1  wherein:
 (a) the pump has a suction side; 
 (b) the cavitation sensor is provided in the fluid circuit on the suction side of the pump. 
 
     
     
         3 . The system of  claim 1  wherein the controller is adapted to stop the operation of the pump when it receives a cavitation signal from the cavitation sensor. 
     
     
         4 . The system of  claim 1  wherein:
 (a) the working machine includes an operator's station from which an operator can operate and monitor the components of the working machine; 
 (b) the controller is operatively connected to the operator's station and is adapted to send a cavitation existence signal to the operator's station when it receives a cavitation signal from the cavitation sensor. 
 
     
     
         5 . The system of  claim 1  wherein the cavitation sensor comprises an accelerometer that is adapted to measure the acceleration of asphalt cement in the asphalt cement fluid circuit. 
     
     
         6 . The system of  claim 1  wherein the cavitation sensor is adapted to detect vibration within the pump of the asphalt cement fluid circuit. 
     
     
         7 . The system of  claim 1  wherein the cavitation sensor comprises an accelerometer that is adapted to measure the change in frequency of the fluid moving within the asphalt cement fluid circuit. 
     
     
         8 . The system of  claim 7  wherein the cavitation sensor is adapted to send a signal to the controller when it detects a frequency range displacement within the range of 3-40 Hz. 
     
     
         9 . The system of  claim 1  wherein the cavitation sensor comprises an accelerometer that is adapted to measure the change in amplitude of the fluid moving within the asphalt cement fluid circuit. 
     
     
         10 . The system of  claim 9  wherein the cavitation sensor is adapted to send a signal to the controller when it detects an amplitude change in peak to peak displacement that is within the range of 0-0.254 mm.