Open Loop Cooling Water System Having Recirculation Pump

Abstract

An open loop cooling water system is for a marine engine. A cooling water inlet receives cooling water from a body of water. A cooling water outlet discharges the cooling water back to the body of water. A cooling water circuit conveys cooling water from the cooling water inlet, through the marine engine, and to the cooling water outlet. A cooling water pump that pumps cooling water from upstream to downstream through the cooling water circuit. A recirculation pump that is located in the cooling water circuit downstream of at least one component of the marine engine and upstream of the cooling water outlet. The recirculation pump is configured to pump cooling water from downstream of the marine engine back into the cooling water circuit upstream of the marine engine. Methods are for cooling a marine engine using an open loop cooling system.

1 . An open loop cooling water system for a marine engine, the open loop cooling water system comprising:
 a cooling water inlet that receives cooling water from a body of water;   a cooling water outlet that discharges the cooling water back to the body of water;   a cooling water circuit that conveys cooling water from the cooling water inlet, through the marine engine, and to the cooling water outlet;   a cooling water pump that pumps cooling water from upstream to downstream through the cooling water circuit; and   a recirculation pump that is located in the cooling water circuit downstream of at least one component of the marine engine and upstream of the cooling water outlet, wherein the recirculation pump is configured to pump cooling water from downstream of the at least one component of the marine engine back into the cooling water circuit upstream of the marine engine;   a recirculation passage extending from the recirculation pump to the cooling water circuit at a recirculation location upstream of the marine engine, wherein the recirculation location is downstream of all non-controlled exit flow paths from the cooling water circuit.   
     
     
         2 . The open loop cooling water system according to  claim 1 , wherein the recirculation pump comprises an electric pump that is electrically powered. 
     
     
         3 . The open loop cooling water system according to  claim 1 , wherein the recirculation pump comprises a mechanical pump that is mechanically powered. 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The open loop cooling water system according to  claim 1 , wherein the non-controlled exit flow paths comprise at least one of a tell-tale outlet and an exhaust sprayer configured to spray cooling water into a flow of exhaust from the marine engine. 
     
     
         7 . The open loop cooling water system according to  claim 1 , wherein the cooling water circuit upstream of the marine engine comprises a water jacket on a catalyst housing, and wherein the recirculation location is upstream of the water jacket on the catalyst housing. 
     
     
         8 . The open loop cooling water system according to  claim 1 , wherein the cooling water circuit upstream of the marine engine comprises a water jacket on an exhaust tube of the marine engine, and wherein the recirculation passage extends from the recirculation pump to the water jacket on the exhaust tube. 
     
     
         9 . The open loop cooling water system according to  claim 8 , wherein the recirculation passage comprises a water jacket on a main bearing oil cooler of the marine engine. 
     
     
         10 . The open loop cooling water system according to  claim 8 , wherein the cooling water circuit upstream of the marine engine comprises a water jacket on a catalyst housing that contains a catalyst for treating exhaust gas from the marine engine, and wherein the water jacket on the exhaust tube conveys cooling water to the water jacket on the catalyst housing. 
     
     
         11 . The open loop cooling water system according to  claim 10 , wherein the cooling water circuit upstream of the marine engine comprises a water jacket on an exhaust manifold that carries exhaust gas from the marine engine to the exhaust tube, and wherein the water jacket on the catalyst housing conveys cooling water to the water jacket on the exhaust manifold. 
     
     
         12 . The open loop cooling water system according to  claim 11 , wherein the cooling water circuit downstream of the water jacket on the exhaust manifold comprises a cooling water passage through a cylinder head of the marine engine, and wherein the water jacket on the exhaust manifold conveys cooling water to the cooling water passage through the cylinder head. 
     
     
         13 . The open loop cooling water system according to  claim 12 , wherein the cooling water circuit downstream of the cooling water passage through the cylinder head comprises a cooling water passage through a cylinder block of the marine engine, and wherein the cooling water passage through the cylinder head carries cooling water through the cooling water passage of the cylinder block. 
     
     
         14 . The open loop cooling water system according to  claim 1 , wherein the recirculation pump comprises a mechanical pump that is driven by an exhaust camshaft of the marine engine. 
     
     
         15 . The open loop cooling water system according to  claim 14 , wherein the mechanical pump is mounted on the exhaust camshaft of the marine engine. 
     
     
         16 . The open loop cooling water system according to  claim 15 , wherein the mechanical pump comprises an impeller that rotates as the exhaust camshaft rotates. 
     
     
         17 . A method of cooling a marine engine, the method comprising pumping cooling water from upstream to downstream through a cooling water circuit that conveys cooling water from a cooling water inlet, through the marine engine, and to a cooling water outlet; pumping cooling water that is located in the cooling water circuit downstream of at least one component of the marine engine and upstream of the cooling water outlet back into the cooling water circuit upstream of the marine engine;
 pumping the cooling water that is located in the cooling water circuit downstream of the marine engine and upstream of the cooling water outlet to a recirculation location in the cooling water circuit that is upstream of the marine engine, wherein the recirculation location is downstream of all non-controlled exit flow paths from the cooling water circuit.   
     
     
         18 . (canceled) 
     
     
         19 . The method according to  claim 17 , wherein the recirculation location is located in a cooling water jacket on an exhaust tube that carries exhaust gases from the marine engine. 
     
     
         20 . The method according to  claim 17 , wherein the recirculation location is located upstream of a water jacket on a catalyst housing that contains a catalyst for treating exhaust gas from the marine engine.