1. Field of the Invention
The present invention relates to valves that prevent backflow of a fluid, and to fluid control apparatuses provided with such valves.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2002-106469 discloses a diaphragm pump provided with a valve.
FIG. 14 is an exploded perspective view illustrating a diaphragm pump 90 according to Japanese Unexamined Patent Application Publication No. 2002-106469. FIG. 15 is a cross-sectional view illustrating the primary components of the diaphragm pump 90 shown in FIG. 14.
The diaphragm pump 90 is configured of a housing 900 provided with an exhaust channel 901 and an intake channel 902, and a diaphragm 910 for forming a pump chamber with the housing 900. The housing 900 is configured of an upper housing portion 930, a lower housing portion 940, and a diaphragm (film) 920.
An intake channel groove portion 942 through which air is sucked into the pump chamber from outside of the housing 900, an exhaust channel groove portion 941 through which air is exhausted from the pump chamber to the outside of the housing 900, an approximately cylindrical recess portion 945, an approximately cylindrical recess portion 946, a cylindrical platform 947 located in the center of the recess portion 946, a projecting portion 944, and a projecting portion 943 are provided in the lower housing portion 940.
The exhaust channel 901, the intake channel 902, a recess portion 935 that opposes the recess portion 945, a recess portion 936 that opposes the recess portion 946, a cylindrical platform 937 located in the center of the recess portion 935, a projecting portion 934 that is bonded to the projecting portion 944, and a projecting portion 933 that is bonded to the projecting portion 943 are provided in the upper housing portion 930. The diaphragm 910 is bonded, using an adhesive, to an outer edge portion in an upper surface of the upper housing portion 930, the outer edge portion being located further toward an outer side portion than the exhaust channel 901 and the intake channel 902.
A hole portion 921A that faces the platform 947 and a hole portion 921B that faces the platform 937 are provided in the diaphragm 920.
The upper housing portion 930 and the lower housing portion 940 are bonded to each other, with the diaphragm 920 located therebetween, using an adhesive. Accordingly, the diaphragm 920 is sandwiched between the upper housing portion 930 and the lower housing portion 940.
As shown in FIG. 15, an intake valve is configured by the recess portions 936 and 946, the platform 947, and the periphery of the hole portion 921A and the hole portion 921A in the diaphragm 920. The intake valve allows a fluid to flow from the intake channel groove portion 942 side toward the diaphragm 910 side but prevents the fluid from flowing from the diaphragm 910 side toward the intake channel groove portion 942 side.
Meanwhile, an exhaust valve is configured by the recess portions 935 and 945, the platform 937, and the periphery of the hole portion 921B and the hole portion 921B in the diaphragm 920. The exhaust valve allows the fluid to flow from the diaphragm 910 side toward the exhaust channel groove portion 941 side but prevents the fluid from flowing from the exhaust channel groove portion 941 side toward the diaphragm 910 side.
The diaphragm pump 90 configured as described above is operated by causing the diaphragm 910 to bend.
When the diaphragm pump 90 is driven, the periphery of the hole portion 921A in the diaphragm 920 separates from the platform 947, and the periphery of the hole portion 921B in the diaphragm 920 separates from the platform 937. As a result, the exhaust valve and intake valve each open, and air flows in from the intake channel groove portion 942 and is exhausted from the exhaust channel groove portion 941.
However, in the diaphragm pump 90, there are cases, during driving, where the pressure on the diaphragm 910 side of the diaphragm 920 increases suddenly. In such a case, in the exhaust valve, the periphery of the hole portion 921B in the diaphragm 920 will separate by a significant amount from the platform 937 and make contact with the recess portion 945 in the lower housing portion 940. In other words, the hole portion 921B is covered by the lower housing portion 940 and the exhaust valve is blocked.
Accordingly, with the diaphragm pump 90, there is a problem in that the diaphragm 920 in the exhaust valve deforms greatly and the transport of fluid will stop in the case where the pressure acting on the diaphragm 910 side of the diaphragm 920 is much higher.