Liquid paint pumping apparatus

Abstract

The invention relates to a liquid paint pumping apparatus comprising a piston reciprocable in a cylinder to pump liquid paint during a substantially horizontal pumping stroke of the piston and to charge the cylinder with paint during a reverse stroke of the piston. The apparatus further comprises a check valve disposed within the piston, the check valve comprising: a ball member, a seat, a spring urging the ball member into engagement with the seat, and a plastics cage guiding movement of the ball towards and away from the seat. The seat receives the ball member so as to form a seal to prevent flow of liquid paint between the ball and the seat during the pumping stroke of the piston, and the ball member moves away from the seat during the reverse stroke of the piston.

1 . A liquid paint pumping apparatus comprising a piston reciprocable in a cylinder to pump liquid paint during a substantially horizontal pumping stroke of the piston and to charge the cylinder with paint during a reverse stroke of the piston, the apparatus further comprises a check valve disposed within the piston, the check valve comprising: a ball member, a seat, a spring urging the ball member into engagement with the seat, and a plastics cage guiding movement of the ball towards and away from the seat;
 wherein the seat receives the ball member so as to form a seal to prevent flow of liquid paint between the ball and the seat during the pumping stroke of the piston, and the ball member moves away from the seat during the reverse stroke of the piston.   
     
     
         2 . A liquid paint pumping apparatus comprising a piston reciprocable in a cylinder and configured to pump liquid paint during a substantially horizontal stroke of the piston, the apparatus further comprises a substantially horizontally mounted check valve comprising:
 a ball member;   a seat for receiving the ball member so as to form a seal to prevent flow of liquid paint between the ball and the seat, the check valve being configured for the ball to move away from the seat under the influence of paint pressure;   a spring providing a biasing force urging the ball member into engagement with the seat;   a plastics cage configured to guide movement of the ball towards and away from the seat; and   a spring keep interposing the spring and the ball member.   
     
     
         3 . The liquid paint pumping apparatus according to  claim 2 , comprising a plurality of substantially horizontally mounted pistons reciprocable in corresponding cylinders. 
     
     
         4 . The liquid paint pumping apparatus according to  claim 3 , wherein the plurality of substantially horizontally mounted pistons are configured to reciprocate out of phase with one another. 
     
     
         5 . A check valve for use in a liquid paint pumping apparatus, the check valve comprising a housing for retaining:
 a ball member;   a seat for receiving the ball member so as to form a seal to prevent flow of liquid paint between the ball and the seat, the check valve being configured for the ball to move away from the seat under the influence of paint pressure;   a plastics cage configured to guide movement of the ball away from the seat and to provide a passage for flow of liquid paint through the housing;   a spring providing a biasing force urging the ball member into engagement with the seat; and
 a spring keep interposing the spring and the ball member. 
   
     
     
         6 . The check valve according to  claim 5 , wherein the plastics cage is separable and removable from the housing. 
     
     
         7 . The check valve of  claim 6 , wherein the check valve is configured for mounting in a vertical orientation such that the ball member lifts away from the seat under the influence of paint pressure. 
     
     
         8 . The check valve of  claim 7 , wherein the spring is a helically coiled spring. 
     
     
         9 . The check valve of  claim 7 , wherein the spring is a compression spring. 
     
     
         10 . The check valve of  claim 8 , wherein the helically-coiled spring is shaped to prevent contact with adjacent surfaces. 
     
     
         11 . The check valve of  claim 10 , wherein the helically-coiled spring has a frusto-conical shape. 
     
     
         12 . The check valve of any of  claim 5 , wherein the spring keep is made of a plastics material. 
     
     
         13 . The check valve of  claim 12 , wherein the plastics material of the spring keep is an acetal resin engineering plastic. 
     
     
         14 . The check valve of  claim 13 , wherein the check valve is configured for operation with the ball member moveable in a substantially horizontal direction. 
     
     
         15 . The check valve of  claim 5 , wherein a plastics material of the plastics cage is an acetal resin engineering plastic. 
     
     
         16 . (canceled) 
     
     
         17 . The liquid paint pumping apparatus according to  claim 1 , comprising a plurality of substantially horizontally mounted pistons reciprocable in corresponding cylinders. 
     
     
         18 . The liquid paint pumping apparatus according to  claim 17 , wherein the plurality of substantially horizontally mounted pistons are configured to reciprocate out of phase with one another. 
     
     
         19 . The liquid paint pumping apparatus according to  claim 1 , wherein the check valve is configured for mounting in a vertical orientation such that the ball member lifts away from the seat under the influence of paint pressure. 
     
     
         20 . The liquid paint pumping apparatus according to  claim 1 , wherein the plastics cage is made of an acetal resin engineering plastic. 
     
     
         21 . The liquid paint pumping apparatus according to  claim 2 , wherein the plastics cage and the spring keep are made of an acetal resin engineering plastic.