Pump with transfer tube

Abstract

A pump uses tubular transfer members for transferring intake and/or exhaust air into the crankcase and/or between valve head chambers. The pump has compact 180° opposed pistons that minimize axial spacing between the pistons on the drive shaft and thereby reduces the shaking couple and noise from reciprocation. Each piston has its own eccentric element press-fit into the connecting rods so as not to occupy space between the pistons. The shaking couple can be further reduced for pistons of different masses by selecting the mass of the cup retainers to compensate for the difference in overall piston masses. The pump includes an improved cylinder sealing arrangement having a circumferential groove in an angled surface at the end of the cylinder. The pump also has a special cover and seal for closing the open neck of the pump crankcase and a multi-lobed valve stop.

1 . A pump, comprising: 
 a crankcase defining a pumping chamber and a transfer opening;    a valve mounting member mounted to the crankcase over the pumping chamber and having a port in communication with the pumping chamber, the port being opened and closed by a valve mounted to the valve mounting member;    a working fluid chamber defined at least in part by the valve mounting member on a side of the valve mounting member opposite from the pumping chamber, said working fluid chamber being in communication with the pumping chamber through the port when the valve is open;    a transfer port in communication with the working fluid chamber, said transfer port being outside of the pumping chamber; and    a transfer tube connected at one end to the transfer port and at the other end to the crankcase transfer opening.    
   
   
       2 . The pump of  claim 1 , wherein the transfer tube has opposite flat side walls.  
   
   
       3 . The pump of  claim 1 , wherein the transfer tube is separate from the valve mounting member and from the crankcase.  
   
   
       4 . The pump of  claim 1 , wherein the transfer tube is formed as a unitary part of the valve mounting member.  
   
   
       5 . The pump of  claim 1 , wherein the crankcase defines an integral passageway leading to the transfer opening.  
   
   
       6 . The pump of  claim 5 , wherein the passageway leads to a crankcase chamber.  
   
   
       7 . The pump of  claim 5 , wherein the passageway leads to a second transfer opening in the crankcase.  
   
   
       8 . The pump of  claim 7 , further including a second transfer tube connecting the passageway to a second working fluid chamber of the pump.  
   
   
       9 . The pump of  claim 5 , wherein the passageway has two flat side walls.  
   
   
       10 . The pump of  claim 8 , wherein the transfer tube is formed as a unitary part of the valve mounting member.  
   
   
       11 . The pump of  claim 10 , further including a resilient seal disposed between the transfer opening and the transfer tube.  
   
   
       12 . The pump of  claim 11 , wherein the transfer tube is separate from the valve mounting member and from the crankcase.  
   
   
       13 . The pump of  claim 12 , wherein the transfer tube is a resilient material.  
   
   
       14 . The pump of  claim 12 , further including resilient seals at each end of the transfer tube.  
   
   
       15 . The pump of  claim 12 , wherein the transfer tube is clamped between the valve mounting member and the crank case.  
   
   
       16 . The pump of  claim 1 , wherein the valve mounting member is a valve plate.  
   
   
       17 . The pump of  claim 16 , wherein the working fluid is air.  
   
   
       18 . The pump of  claim 1 , wherein the working fluid chamber is an intake chamber.  
   
   
       19 . The pump of  claim 1 , wherein the working fluid chamber is an exhaust chamber.  
   
   
       20 . A pump, comprising: 
 a crankcase defining two pumping chambers in which a working fluid is pumped and defining a passageway opening at at least two transfer openings at opposite sides of the crankcase;    two valve mounting members mounted to the crankcase that close the pumping chambers, each valve mounting member having a valve port in communication with the pumping chamber, the valve port being opened and closed by a valve mounted to the valve mounting member, each valve mounting member further having a transfer port;    at least two working fluid chambers, each said working fluid chamber defined at least in part by one or the other of the valve mounting members on a side of said valve mounting member opposite from the pumping chamber of the pump that is adjacent to said valve mounting member, each said working fluid chamber being in communication with the adjacent pumping chamber when the valve port of the adjacent valve mounting member is open; and    a transfer tube connected between the transport ports of the valve mounting members and the crankcase transfer openings to connect each working fluid chamber to the passageway.    
   
   
       21 . The pump of  claim 20 , wherein: 
 said at least two working fluid chambers are connected to each other through the transfer tube.    
   
   
       22 . The pump of  claim 20 , wherein: 
 said at least two working fluid chambers are connected to a chamber of the crankcase through the transfer tube.    
   
   
       23 . The pump of  claim 20 , wherein: 
 the chambers are intake chambers.    
   
   
       24 . The pump of  claim 20 , wherein: 
 the chambers are exhaust chambers.    
   
   
       25 . The pump of  claim 20 , wherein: 
 at least one of the chambers is an intake chamber and at least one of the chambers is an exhaust chamber.