In the related art, liquid delivery devices that deliver a liquid stored in a liquid storage unit to a liquid consumption unit via a valve are known such as the device described in International Publication No. 2010/137578 (hereinafter “Patent Document 1”).
FIG. 17 is an outline structural view of a liquid delivery device 800 described in Patent Document 1. This liquid delivery device 800 includes a fuel cartridge 1 (liquid storage unit) that stores a liquid fuel, a pressure resistant valve 2, a passive valve 3, a pump 4 that transports the fuel, a power generating cell 5 (liquid consumption unit) that receives supply of the fuel from the pump 4 and generates power, and channels 7 and 8. The fuel is for example methanol.
The pump 4 includes a suction aperture 41 through which the fuel is sucked, a discharge aperture 42 through which the fuel is discharged, and check valves 43 and 44 that prevent reverse flow of the fuel.
The passive valve 3 includes a valve casing 10 and a diaphragm 20 that partitions the interior of the valve casing 10 to form a first valve chamber 11 and a second valve chamber 12 inside the valve casing 10.
A first opening 15 that is in communication with the first valve chamber 11, a second opening 16 that is in communication with the second valve chamber 12, and a third opening 17 that is in communication with the first valve chamber 11 are formed in the valve casing 10. In addition, the valve casing 10 is provided with an O-ring (valve seat) 30 that protrudes from the periphery of the third opening 17 towards the diaphragm 20 side and is in contact with the diaphragm 20.
The fuel cartridge 1 is connected to the second opening 16 of the passive valve 3 and the suction aperture 41 of the pump 4 via the pressure resistant valve 2 and the channel 7. The discharge aperture 42 of the pump 4 is connected to the first opening 15 via the channel 8. In addition, the third opening 17 is connected to the power generating cell 5.
In the above-described configuration, when operation of the pump 4 is started, the fuel stored in the fuel cartridge 1 flows into the first valve chamber 11 from the first opening 15 via the pressure resistant valve 2, the channel 7, the pump 4 and the channel 8, and the pressure of the fuel is increased inside the first valve chamber 11.
As a result, the diaphragm 20 of the passive valve 3 curves toward the second valve chamber 12 side and becomes separated from the O-ring 30, and the first opening 15 and the third opening 17 come to be in communication with each other. That is, the passive valve 3 is opened.
Thus, the fuel stored in the fuel cartridge 1 is supplied to the power generating cell 5 via the pressure resistant valve 2, the channel 7, the pump 4, the channel 8, and the passive valve 3 by operation of the pump 4. The power generating cell 5 receives supply of the fuel and generates power.
However, the pump 4 described in Patent Document 1 has a P-Q (pressure-flow rate) characteristic as illustrated in FIG. 18. That is, when the pressure P (difference between discharge-side pressure and suction-side pressure varies, the flow rate Q varies. Consequently, in the liquid delivery device 800, there is a problem in that if a change occurs in the surrounding environment such as the channel resistance of for example a tube that connects the passive valve 3 and the power generating cell 5, the discharge-side pressure varies and the flow rate changes and therefore the flow rate of the fuel supplied to the power generating cell 5 is not stable.
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