JP2007192202A - Pump and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a sealing ability between a rotary shaft and housing without using sealing material. <P>SOLUTION: A hydrogen circulation pump 1 supplies a discharged fuel from a fuel cell 3 to the fuel cell 3 again by circulating via a hydrogen circulation passage 15, and comprises an impeller 39 beneath a rotary shaft 33 of motor 50 equipped with a motor coil 49. A spiral projection 33b is arranged in the periphery 33a of the rotary shaft 33 above the impeller 39, and a condensation water willing to permeate into a gap 53 of periphery side of the rotary shaft 33 from a pump housing 41 is transfered to the pump housing 41 side by a revolution of the rotary shaft 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pump and a fuel cell system in which an impeller is provided on a rotating shaft of a motor unit.

2. Description of the Related Art Conventionally, in a pump in which an impeller is provided on one end side of a pump shaft that is a rotating shaft and the other end side of the pump shaft is connected to a motor unit, as described in Patent Document 1, for example, an impeller side and a motor When sealing between the pump shaft and the pump housing at the boundary with the part side, it is usual to use a sealing material.
JP-A-5-18389

  However, the sealing material used for shaft sealing as described above causes seal leakage due to deterioration due to high temperature during high-speed rotation and wear due to friction with the rotating shaft. Causes output to drop.

  Then, this invention aims at ensuring the sealing performance between a rotating shaft and a housing, without using a sealing material.

  The present invention provides a pump provided with an impeller on a rotating shaft of a motor unit, an outer peripheral surface of the rotating shaft between the motor unit and the impeller, and an inner surface of a housing facing the outer peripheral surface of the rotating shaft. There is a gap between the outer peripheral surface of the rotary shaft and the inner peripheral surface of the housing, and the fluid in the gap is rotated from the motor unit side by the rotation of the rotary shaft. The main feature is the provision of a spiral portion that moves toward the impeller side.

  According to the present invention, the fluid that is going to enter the motor unit side from the impeller side flows from the motor unit side to the impeller side along the spiral portion by rotating the rotation shaft of the motor unit. Intrusion of fluid from the impeller side to the motor unit side can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a hydrogen circulation pump 1 as a fuel circulation pump used in the fuel cell system of FIG. 2 showing a first embodiment of the present invention. In the fuel cell system shown in FIG. 2, a hydrogen inlet 3 a of the fuel cell 3 and a hydrogen tank 5 that stores hydrogen gas as fuel are connected by a hydrogen supply passage 7. The hydrogen pressure regulating valve 9 and the hydrogen pressure sensor 11 are sequentially installed from the side.

  The hydrogen pressure sensor 11 detects the hydrogen pressure in the hydrogen supply passage 7, and a control unit 13 that takes in this detection signal controls the hydrogen pressure regulating valve 9 to open and close to adjust the amount of hydrogen supplied from the hydrogen tank 5.

  One end of a hydrogen circulation passage 15 as a fuel circulation passage is connected to the hydrogen outlet 3 b of the fuel cell 3, and the other end of the hydrogen circulation passage 15 is connected to the hydrogen supply passage 7 described above. The hydrogen circulation pump 1 corresponding to the pump of the present invention is installed in the hydrogen circulation passage 15. Further, a discharge passage 17 is provided in the hydrogen circulation passage 15 between the hydrogen circulation pump 1 and the hydrogen outlet 3 b of the fuel cell 3, and a purge valve 19 is provided in the discharge passage 17. The purge valve 19 is appropriately opened and closed by the control unit 13 described above, and discharges the reaction gas from the discharge passage 17 to the outside.

  On the other hand, the air inlet 3 c of the fuel cell 3 and the air compressor 21 are connected by an air supply passage 23, and an air discharge passage 25 is connected to the air outlet 3 d of the fuel cell 3. An air pressure sensor 27 is installed in the air supply passage 23, and an air pressure regulating valve 29 is installed in the air discharge passage 25.

  The air pressure sensor 27 detects the air pressure in the air supply passage 23, and the control unit 13 that takes in this detection signal controls the rotation speed of the air compressor 21 and also controls the opening and closing of the air pressure regulating valve 29 to control the fuel cell. 3 is adjusted, and the pressure in the air supply passage 23 is adjusted.

  Next, the structure of the hydrogen circulation pump 1 will be described with reference to FIG. In the housing 31, a rotary shaft 33 extending in the vertical direction in FIG. 1 is rotatably accommodated via bearings 35 and 37 at both upper and lower ends. An impeller 39 is fixed to the lower part of the rotating shaft 33 in a state of being accommodated in the pump chamber 41. A fluid flow path 43 is provided in the upper part on the outer peripheral side of the pump chamber 41. The fluid flow path 43 is formed so as to communicate with the suction port 45 at the right end and the discharge port 47 at the left end in FIG. To do.

  A motor coil 49 is provided on the housing 31 on the upper outer peripheral side of the rotating shaft 33 in FIG. 1 to constitute a motor stator. On the outer peripheral surface of the rotating shaft 33 facing the motor coil 49, a permanent magnet 51 is circular. A plurality of motor rotors are provided along the circumferential direction to constitute a motor rotor, thereby constituting the motor unit 50.

  Therefore, the hydrogen circulation pump 1 shown in FIG. 1 is provided with the impeller 39 on the rotating shaft 33 of the motor unit 50.

  Here, an annular gap 53 is provided between the outer circumferential surface 33 a of the rotating shaft 33 and the inner circumferential surface 31 a of the housing 31 facing the rotating shaft 33, and a spiral that becomes a spiral portion protruding toward the gap 53. A protrusion 33 b is formed on the outer peripheral surface 33 a of the rotating shaft 33. The spiral protrusion 33b is formed from the portion where the impeller 39 on the rotating shaft 33 is provided to the substantially center of the portion where the motor coil 49 is provided. For this reason, the plurality of permanent magnets 51 may be divided along the axial direction by the protrusions 33b.

  In the fuel cell system including the hydrogen circulation pump 1 having such a structure, the fuel in the hydrogen tank 5 is decompressed and adjusted by the hydrogen pressure regulating valve 9 when flowing through the hydrogen supply passage 7, and then the fuel cell. 3, air compressed by the air compressor 21 is supplied to the fuel cell 3 through the air supply passage 23, and the fuel cell 3 generates electricity with the supplied hydrogen and air.

  The fuel cell 3 in the power generation state discharges surplus fuel to the hydrogen circulation passage 15, and this discharged hydrogen is supplied to the fuel cell 3 again through the hydrogen supply passage 7 by driving the hydrogen circulation pump 1, while the air to be discharged Through the air discharge passage 25.

  Here, in the hydrogen circulation pump 1, the rotating shaft 33 rotates in a certain direction by the drive of the motor unit 50, and the impeller 39 rotates accordingly, so that the discharged hydrogen flowing out from the fuel cell 3 to the hydrogen circulation passage 15. Is sucked into the pump chamber 41 from the suction port 45 and then discharged from the discharge port 47 to the hydrogen circulation passage 15 on the hydrogen supply passage 7 side.

  At this time, the hydrogen discharged from the fuel cell 3 contains condensed water. When this condensed water flows into the pump chamber 41, the fluid is transferred by the spiral protrusion 33 b accompanying the rotation of the rotating shaft 33. Intrusion of condensed water into the gap 53 can be prevented, and moisture can be prevented from entering the motor unit 50, particularly the motor coil 49. In this way, by preventing the condensate, which is a conductive fluid, from entering the motor unit 50, it is possible to prevent a decrease in insulation resistance of electrical components such as the motor coil 47, and to operate the fuel cell system stably. It becomes possible.

  For example, even if the condensed water enters the gap 53 from the pump chamber 41, the spiral protrusion 33b accompanying the rotation of the rotary shaft 33 causes a fluid transfer action from the motor unit 50 side to the impeller 39 side. The condensed water in the gap 53 can be sent to the pump chamber 41 side, and the intrusion of condensed water into the motor unit 50 can be avoided.

  Here, as shown in FIG. 3A, the above-described hydrogen circulation pump 1 increases the amount of condensed water transferred by the protrusion 33b as the hydrogen circulation flow rate Q increases, and also as shown in FIG. 3B. In addition, when the hydrogen circulation flow rate Q increases, the rotational speed of the rotary shaft 33 also increases. Therefore, the rotation speed of the hydrogen circulation pump 1 and the amount of condensed water transferred are proportional.

  When the hydrogen circulation flow rate Q is large, a large amount of condensed water enters the hydrogen circulation pump 1. At this time, since the rotation speed of the hydrogen circulation pump 1 is high, a large amount of condensed water can be transferred. On the contrary, when the hydrogen circulation flow rate Q is small, the condensed water entering the hydrogen circulation pump 1 is reduced, but the condensed water can be appropriately transferred because the rotation speed of the hydrogen circulation pump 1 is low.

  Thus, by providing the spiral projection 33b on the outer peripheral surface 33a of the rotating shaft 33, a fluid transfer effect corresponding to the amount of condensed water can be obtained, and the prevention of intrusion of condensed water into the motor unit 50 is efficient. Can be done automatically.

  FIG. 4 is a sectional view of a hydrogen circulation pump 1A showing a second embodiment of the present invention. The hydrogen circulation pump 1A in this embodiment has a spiral groove 33c formed on the outer peripheral surface 33a of the rotary shaft 33 in place of the spiral protrusion 33b of the hydrogen circulation pump 1 in the first embodiment shown in FIG. Provided. Other configurations are the same as those of the first embodiment.

  Also in the second embodiment, the fluid transfer action of the spiral groove 33c accompanying the rotation of the rotary shaft 33 can prevent the intrusion of condensed water into the gap 53, and even if the condensed water enters into the gap 53, for example. The infiltrated condensed water can be transferred to the impeller 39 side, and the infiltration of condensed water into the motor unit 50 can be avoided.

  1 may be provided on the inner peripheral surface 31a of the housing 31 in place of the spiral protrusion 33b provided on the rotary shaft 33 of FIG. 1 or the spiral groove 33c of FIG. In addition, these spiral protrusions and grooves may be provided on both the outer peripheral surface 33a, the housing 31, and the inner peripheral surface 31a of the rotating shaft.

  As a third embodiment of the present invention, although not particularly illustrated, in the hydrogen circulation pump 1 of the first embodiment shown in FIG. 1 or the hydrogen circulation pump 1A of the second embodiment shown in FIG. The axial interval between the spiral projection 33b and the spiral groove 33c is changed between the motor unit 50 side and the impeller 39 side. Specifically, the axial distance between the protrusion 33b and the groove 33c is narrowed on the motor unit 50 side and widened on the impeller 39 side.

  By the way, since the condensed water flows into the pump chamber 41 from the hydrogen circulation passage 15, a large amount of condensed water accumulates below the pump chamber 41 side of the rotary shaft 33, while compared to the lower portion above the motor unit 50 side. It will be less.

  Therefore, by narrowing the interval between the spiral projections 33b and the grooves 33c in the upper part in FIG. 1 where there is little condensed water, the number of times that the condensed water is scraped out can be increased and the ability to transfer condensed water can be enhanced. On the contrary, if the interval between the spiral projections 33b and the grooves 33c in the lower part in FIG. 1 where a large amount of condensed water accumulates is reduced, the resistance when the fluid transfer action is performed increases and the pump efficiency deteriorates. By expanding the above-mentioned interval between the portions where a large amount of condensed water accumulates, a large amount of condensed water can be efficiently transferred.

  Although not particularly shown as the fourth embodiment of the present invention, at least the outer peripheral surface 33a of the rotary shaft 33 and the inner peripheral surface 31a of the housing 31 in the hydrogen circulation pump of each of the first to third embodiments described above. Either one is water-repellent.

  On the outer peripheral surface 33a of the rotating shaft 33 and the inner peripheral surface 31a of the housing 31 subjected to the water repellent treatment as described above, surface tension is generated in the infiltrated condensed water. The condensed water on the surface 33a and the inner peripheral surface 31a is easily separated, and the condensed water can be transferred to the pump chamber 41 side more efficiently.

  Although not particularly illustrated as the fifth embodiment of the present invention, at least the outer peripheral surface 33a of the rotary shaft 33 and the inner peripheral surface 31a of the housing 31 in the hydrogen circulation pump of each of the first to third embodiments described above. Either one is subjected to a hydrophilic treatment.

  On the outer peripheral surface 33a of the rotating shaft 33 and the inner peripheral surface 31a of the housing 31 that have been subjected to hydrophilic treatment as described above, the infiltrated condensed water becomes familiar, so by rotating the rotating shaft 33, the outer peripheral surface 33a and the inner peripheral surface The condensed water on the surface 31a can easily flow, and the condensed water can be transferred to the pump chamber 41 side more efficiently.

  FIG. 5 is a cross-sectional view of a hydrogen circulation pump 1B showing a sixth embodiment of the present invention. The hydrogen circulation pump 1B in this embodiment is a spiral shape of the rotary shaft 33 of the hydrogen circulation pump 1 in the first embodiment shown in FIG. 1 or the hydrogen circulation pump 1A in the second embodiment shown in FIG. An annular recess 55 is provided at an upper position of the projection 33b or the groove 33c. Other configurations are the same as those of the first embodiment and the second embodiment.

  In the sixth embodiment, a spiral projection 33b or groove 33c is provided on the outer peripheral surface 33a of the rotating shaft 33, so that the pump chamber 41 has the same effect as the first embodiment and the second embodiment. Even if the condensed water in the inside enters the motor unit 50 side through the gap 53, the condensed water once enters and is captured in the recess 55 provided on the upper portion of the rotating shaft 33. Therefore, the condensed water is condensed to the motor coil 49. Infiltration of water can be prevented.

  Instead of providing the concave portion 55 on the outer peripheral surface 33a of the rotating shaft 33, a concave portion may be provided on the inner peripheral surface 31a of the housing 31 on the lower side in FIG. The recess for capturing water may be provided on both the outer peripheral surface 33a of the rotating shaft and the inner peripheral surface 31a of the housing 31.

  As a seventh embodiment of the present invention, although not particularly shown, when the operation of the fuel cell 3 is stopped, any one of the hydrogen circulation pumps 1, 1A, 1B in the first to sixth embodiments described above is used. Then, the control unit 13 is operated for a predetermined time according to the command.

  As a result, the condensed water remaining in the gap 41 on the outer peripheral side of the rotating shaft 33 when the fuel cell 1 is stopped can be transferred and discharged to the pump chamber 41 side, and can be discharged to the motor coil 49 when the fuel cell 1 is stopped. Infiltration of condensed water can be prevented, the insulation resistance of the motor coil 49 at the start of the next operation can be ensured as desired, and a stable operation as a fuel cell system can be performed.

  FIG. 6 is an overall configuration diagram of a fuel cell system showing an eighth embodiment of the present invention. In the eighth embodiment, a timer 57 as time measuring means for measuring the elapsed time after the operation of the fuel cell 3 is stopped is added to the first embodiment shown in FIG. Other configurations are the same as those of the first embodiment.

  As shown in the flowchart of FIG. 7, when the timer 57 measures an arbitrary time n1 after the operation of the fuel cell 3 is stopped (step 701), the control unit 13 takes in the measurement signal and based on this. The hydrogen circulation pump 1 is operated for an arbitrary fixed time (n2) (steps 703, 705, and 707).

  The arbitrary fixed time n1 after the operation of the fuel cell 3 is stopped is a time after the fuel cell 3 is stopped, the temperature in the hydrogen circulation pump 1 decreases and the moisture contained in the hydrogen can condense. As a result, not only the condensed water remaining in the gap 53 but also the condensed water condensed due to the temperature drop can be transferred to the pump chamber 41, and the condensed water after the fuel cell 3 is stopped is supplied to the motor unit 50. Intrusion can be reliably prevented.

  FIG. 8 is an overall configuration diagram of a fuel cell system showing a ninth embodiment of the present invention. In the eighth embodiment, a temperature sensor 59 as temperature means for detecting the temperature of the discharged fuel discharged from the fuel cell 3 is additionally provided in the first embodiment shown in FIG. Other configurations are the same as those of the first embodiment.

  As shown in the flowchart of FIG. 9, when the temperature sensor 59 detects that the temperature of the exhausted fuel after stopping the operation of the fuel cell 3 has decreased to a predetermined temperature t1, the control unit 13 outputs the detection signal. Then, based on this, the hydrogen circulation pump 1 is operated for an arbitrary time t2 (steps 903, 905, and 907).

  The arbitrary predetermined temperature t1 of the discharged fuel after the operation of the fuel cell 3 is stopped is a temperature that is lowered until the water contained in the hydrogen can be condensed after the fuel cell 3 is stopped. In addition to the condensed water remaining in 53, the condensed water condensed due to the temperature drop can be transferred and discharged to the pump chamber 41, and the condensed water enters the motor unit 50 after the fuel cell 3 is stopped. It can be surely prevented.

  In the above-described ninth embodiment, the temperature sensor 59 directly detects the temperature of the exhaust fuel, but it may be configured to indirectly detect the exhaust fuel. For example, the temperature sensor 59 detects the temperature in the vicinity of the pump chamber 41 of the hydrogen circulation pump 1 so that the temperature of the discharged fuel can be indirectly detected.

It is sectional drawing of the hydrogen circulation pump used for the fuel cell system of FIG. 2 which shows the 1st Embodiment of this invention. 1 is an overall configuration diagram of a fuel cell system showing a first embodiment. (A) is a correlation diagram between the hydrogen circulation flow rate of the hydrogen circulation pump shown in FIG. 1 and the condensed water transfer amount, and (b) is a correlation diagram between the hydrogen circulation flow rate and the shaft rotational speed. It is sectional drawing of the hydrogen circulation pump which shows the 2nd Embodiment of this invention. It is sectional drawing of the hydrogen circulation pump which shows the 6th Embodiment of this invention. It is a whole block diagram of the fuel cell system which shows the 8th Embodiment of this invention. It is a flowchart concerning 8th Embodiment. It is a whole block diagram of the fuel cell system which shows the 9th Embodiment of this invention. It is a flowchart concerning a 9th embodiment.

Explanation of symbols

1,1A, 1B Hydrogen circulation pump (fuel circulation pump)
15 Hydrogen circulation passage (fuel circulation passage)
31 Housing 31a Inner peripheral surface of housing 33 Rotating shaft 33a Outer peripheral surface of rotating shaft 33b Spiral projection (spiral portion)
33c Spiral groove (spiral part)
39 Impeller 50 Motor portion 55 Recessed portion provided on upper outer peripheral surface of rotation shaft 57 Timer (time measuring means)
59 Temperature sensor (temperature detection means)

Claims (11)

  In a pump provided with an impeller on a rotating shaft of a motor unit, an outer peripheral surface of the rotating shaft between the motor unit and the impeller and an inner peripheral surface of a housing facing the outer peripheral surface of the rotating shaft. There is a gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the housing, and the fluid in the gap is moved from the motor unit side to the impeller side by rotation of the rotating shaft. A pump characterized in that a spiral portion is provided to move toward the head.   The pump according to claim 1, wherein the spiral portion includes a spiral protrusion.   The pump according to claim 1, wherein the spiral portion includes a spiral groove.   The pump according to any one of claims 1 to 3, wherein an interval in the axial direction of the spiral portion is changed between the motor portion side and the impeller side.   5. The pump according to claim 1, wherein water repellent treatment is performed on at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the housing.   5. The pump according to claim 1, wherein at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the housing is subjected to a hydrophilic treatment.   The pump according to any one of claims 1 to 6, wherein a recess is provided in at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the housing in the vicinity of the motor unit. .   The pump according to any one of claims 1 to 7 is a fuel circulation pump that circulates exhaust fuel discharged from a fuel cell through a fuel circulation passage and supplies the fuel again to the fuel cell. Is provided in the fuel circulation passage.   9. The fuel cell system according to claim 8, wherein when the operation of the fuel cell is stopped, the fuel circulation pump is operated.   10. The fuel circulation pump according to claim 9, further comprising a time measuring unit that measures an elapsed time after the operation of the fuel cell is stopped, and the time measuring unit measures a predetermined time. Fuel cell system.   Temperature detecting means for detecting the temperature of the discharged fuel discharged from the fuel cell is provided, and this temperature detecting means detects that the temperature of the discharged fuel after the operation of the fuel cell has been reduced to a predetermined temperature. The fuel cell system according to claim 9, wherein when the fuel circulation pump is operated, the fuel circulation pump is operated.