Marine engine pressure relief valve

Details Marine engine pressure relief valve Marine engine pressure relief valve

2000-05-11

2004-12-28

Yuen, Henry C. (Department: 3617)

Internal-combustion engines

Cooling

Automatic coolant flow control

C123S041720

Reexamination Certificate

active

06834624

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates generally to marine engines and, more specifically, to cooling engine components during engine operation.
Marine engines typically include a cooling system for cooling at least portions of the engine exhaust system and the engine cylinders. For example, and in a known V-type marine engine, cooling water is supplied into a space between the cylinder banks, sometimes referred to herein as the engine valley. Water flows from the valley and to each cylinder bank. Specifically, a flow path is provided from the valley to each cylinder bank.
With at least some known marine engines, each cylinder bank includes a valve connected in series in a flow path between the cylinder water jackets and cylinder head water jackets.
Generally, the valve is normally closed, and opens when pressure of the cooling water exceeds a pre-set pressure. When the valve opens, cooling water is supplied to the cylinder head jacket. Since a blow off valve is provided for each cylinder bank, the cylinder banks may not necessarily be balanced. For example, if the valve for one cylinder bank is not adjusted exactly the same as the other valve for the other cylinder bank, then the cylinder banks will not be balanced in that one bank will operate hotter than the other cylinder bank. Balanced operation of the cylinder banks facilitates efficient operation of the engine.
BRIEF SUMMARY OF THE INVENTION
The present invention, in one aspect, is a pressure responsive valve for a marine engine that facilitates balanced operation of the engine. In an exemplary embodiment, the valve includes a first chamber and a second chamber. Cooling water is supplied to the valve first chamber, and the cylinder head water jackets of the engine are in flow communication with the valve second chamber. A flow channel is between the valve first and second chambers, and a plunger is biased to close the flow channel to normally prevent flow from the first chamber to the second chamber. A diaphragm is coupled to the plunger.
During operation of the engine at low speeds, i.e., at low revolutions per minute (rpm), coolant flows to and fills the valve first chamber, and the pressure of the coolant in the valve first chamber is not sufficient to overcome the forces that bias the plunger to the closed position. As the engine speed increases, the coolant pressure also increases which results in greater forces acting on the plunger in a direction which causes the plunger to move from the closed position to an open position.
Once the engine speed reaches a sufficiently high rpm so that the coolant pressure exceeds a pre-set pressure, then the coolant pressure in the first chamber overcomes the biasing forces on the plunger, which causes the plunger to move from the closed position to the open position. When the plunger is in the open position, coolant flows from the first chamber to the second chamber. As a result, coolant flows through the valve to the cylinder head cooling jackets.
Since coolant to both cylinder head cooling jackets flows through the pressure responsive valve, the coolant flow to both cylinder head cooling jackets is about the same, which facilitates balanced cooling of each cylinder bank. Such balanced cooling of each cylinder bank facilitates balanced, and efficient operation, of the engine cylinders.


REFERENCES:
patent: 3918418 (1975-11-01), Horn
patent: 3939807 (1976-02-01), Eichinger
patent: 4140089 (1979-02-01), Kueny et al.
patent: 4621595 (1986-11-01), Suzuki
patent: 4669988 (1987-06-01), Breckenfeld et al.
patent: 4674449 (1987-06-01), Hundertmark
patent: 5330376 (1994-07-01), Okumura
patent: 5937802 (1999-08-01), Bethel et al.
patent: 5970926 (1999-10-01), Tsunoda et al.
patent: 6135833 (2000-10-01), Tsunoda

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