Fluid handling – Systems – Multi-way valve unit
Patent
1996-09-04
1997-11-18
Fox, John
Fluid handling
Systems
Multi-way valve unit
13762544, F16K 1104
Patent
active
056877641
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a four-port valve which has four ports and is suitable for switching directions of the flow of two types of fluid. More particularly, the present invention relates to a four-port valve for controlling directions of the flow of two types of fluid having different temperatures, e.g., a passage for flowing a high-temperature gas such as combustion exhaust gas and a passage for flowing low-temperature gas such as combustion air by changing over the passages to be connected.
BACKGROUND OF THE INVENTION
In recent years, there has been developed a technique for recovering a considerable quantity of heat from exhaust gas utilizing a regenerator to preheat combustion air. For example, there has been proposed a regenerative burner system in which supply of the combustion air to a burner and emission of the combustion exhaust gas from a combustion chamber are alternately carried out through the regenerator and the combustion air is preheated using heat of the combustion exhaust gas accumulated in the regenerator.
In such a regenerative burner system, a four-way passage change-over apparatus is required for switching a passage through which the high-temperature exhaust gas flows with a passage through which the low-temperature combustion air flows to the regenerator to control directions of the flow. Conventionally, four solenoid valves are generally adopted as this passage change-over apparatus in the combustion system, and passages for the high-temperature gas and the low-temperature gas can be changed over by selectively opening and/or closing the solenoid valves provided at four positions. Since the passage change-over apparatus constituted by the solenoid valves however requires a plurality of expensive solenoid valves, the facility cost is disadvantageously increased. In particular, if the apparatus is adopted for heat exchange in the combustion system, a plurality of more expensive solenoid valves for high-temperature use are required, increasing the facility cost. Further, since a dimension of a pneumatic piping solenoid valve is comparatively large, use of four pneumatic piping solenoid valves disadvantageously involves a large space and complicated double piping. Furthermore, when the air and the exhaust gas are frequently switched Within one minute, there is a problem in durability of the solenoid valve.
Therefore, it is desired to change over the fluid by a single passage change-over means having a relatively-simple structure. As the single passage change-over means, employment of a four-way change-over valve 101 which is one kind of a four-port valve such as shown in FIGS. 5A and 5B can be generally considered. This four-directional control valve 101 communicates adjacent two ports among four ports 102, 103, 104 and 105 with each other by a change-over valve member 107 rotating in a casing 106 having four ports 102, . . . , 105, thereby switching the passages.
However, in the structure of the prior art four-way valve, gaps S1 and S2 must be provided between the directional control valve member 107 and a casing 106 provided therearound in the axial direction and the radial direction so as not to bring the change-over valve member 107 into contact with the inner surface of the casing 106 and, depending on the situation, a sealing mechanism must be provided at the gaps. In particular, if there is a large difference in temperature between the two kinds of fluid, the gaps must be provided in accordance with the high temperature, and the gaps necessarily become larger at the low temperature, resulting in a short pass of the two passages in the valve which may leads to leakage of gas. For example, when this valve is used in the regenerative burner system, the combustion air continuously leaks to the passages of the exhaust gas in the four-way valve and, since a quantity of leakage is not fixed and not clear, an excess air ratio of combustion can not be disadvantageously controlled. Moreover, the great drive force is required depending on the friction wh
REFERENCES:
patent: 1547471 (1925-07-01), Achern
patent: 3973592 (1976-08-01), Cleaver et al.
Matsuo Mamoru
Miyata Makoto
Tanaka Ryoichi
Fox John
Nippon Furnace Kogyo Kabushiki Kaisha
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