Leakproof pump for use in an inking mechanism of a rotary printing press

Abstract

A plurality of pump units are juxtaposed for conjointly metering ink to an offset printing press. Each pump unit has a piston slidably received in a cylinder having formed therein a suction port and a discharge port at circumferential spacings. Conventionally pressure-tightly closed at one end, the cylinder has the piston projecting from the other end thereof. The projecting end of the piston is coupled to a drive motor via a drive linkage such that the piston both rotates and linearly reciprocates with each complete revolution of the motor for drawing ink into the cylinder through the suction port and forcing it out through the discharge port. A cylinder end seal is provided for sealing said other end of the cylinder against the leakage of the printing ink.

What is claimed is:  
     
         1 . A pump capable of metering a fluid such as printing ink, comprising: 
 (a) pump body means defining a bore which is pressure-tightly closed at a first end thereof, together with a suction port and a discharge port which are both open to the bore in preassigned different angular positions thereon;    (b) a piston slidably received in the bore in the pump body means for both rotation and linear reciprocation relative to the same and having one end projecting from a second end of the bore, the piston being capable of blocking both suction port and discharge port and alternately placing the same in communication with the bore during each complete revolution thereof;    (c) a drive motor mounted to the pump body means and having a drive shaft rotatable about an axis intersecting the axis of rotation of the piston at a prescribed angle;    (d) a drive linkage connecting the drive shaft of the drive motor to the piston so as to cause joint rotation and linear reciprocation of the latter in response to the rotation of the former; and    (e) end seal means sealing the second end of the bore against the leakage of the fluid from between the pump body means and the piston.    
     
     
         2 . The pump of  claim 1  wherein the pump body means comprises a pump body, and a cylinder mounted fast thereto and defining the bore, and wherein the end seal means is received in a bore enlargement formed in the cylinder at the second end of the bore.  
     
     
         3 . The pump of  claim 2  wherein the end seal means comprises: 
 (a) a sealing ring in fluid-tight contact with both the piston and the cylinder; and  
 (b) a retainer ring positively engaged in the enlargement of the bore in the cylinder for retaining the sealing ring in position.  
 
     
     
         4 . The pump of  claim 3  wherein the sealing ring has a pair of annular, concentric lips formed thereon and elastically held against the piston and the cylinder.  
     
     
         5 . The pump of  claim 1  wherein the pump body means comprises a pump body, and a cylinder mounted fast thereto and defining the bore, and wherein the end seal means comprises: 
 (a) a sealing ring fluid-tightly surrounding the piston and fluid-tightly held against an end of the cylinder; and  
 (b) a mounting ring surrounding the piston and screw-threadedly engaged with the cylinder for positively retaining the sealing ring in position on the piston.  
 
     
     
         6 . The pump of  claim 5  wherein the end seal means further comprises a second sealing ring mounted between the cylinder and the mounting ring for sealing a joint therebetween.  
     
     
         7 . The pump of  claim 5  wherein the sealing ring has a pair of annular, concentric lips formed thereon and elastically held against the piston and the mounting ring.  
     
     
         8 . The pump of  claim 1  wherein the pump body means comprises a pump body having the bore formed directly therein, and wherein the end seal means comprises: 
 (a) a sealing ring fluid-tightly surrounding the piston and fluid-tightly held against the pump body; and  
 (b) a mounting ring surrounding the piston and fastened to the pump body for positively retaining the sealing ring in position on the piston.  
 
     
     
         9 . The pump of  claim 8  wherein the end seal means further comprises a second sealing ring mounted between the pump body and the mounting ring for sealing a joint therebetween.  
     
     
         10 . The pump of  claim 8  wherein the sealing ring has a pair of annular, concentric lips formed thereon and elastically held against the piston and the mounting ring.