JP2004162904A - Roller bearing for fuel cells - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the amount of dust and dirt generated by a roller bearing which is assembled in a force-feeding apparatus of a fuel cell system. <P>SOLUTION: The roller bearing for fuel cells is assembled in the force-feeding apparatus of the fuel cell system having a fuel cell stack and the force-feeding apparatus conveying various fluid. Grease in which lubricating oil with steam pressure of 1.3 × 10<SP>-1</SP>Pa or less at 25 °C becomes base oil is filled in the rolling bearing. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention gasifies a fuel such as methanol or water, reforms it in a reformer, removes CO with a CO remover, and supplies fuel to a fuel cell stack (fuel cell body) to generate power. A fuel cell system or a fuel cell system that supplies hydrogen as fuel from a hydrogen storage means such as a hydrogen tank or a hydrogen storage alloy to a fuel cell stack, or generates hydrogen from a hydrogen-containing compound such as methanol water using a reformer. In a fuel cell system that removes impurities and removes impurities with an impurity remover such as a CO remover, supplies hydrogen to the fuel cell stack, and generates power, it is used as a pump for pumping various fluids between devices. The present invention relates to a rolling bearing for a fuel cell.

  The use of fuel cells as power sources for automobiles, ships, spacecraft, etc. is being studied. However, solid polymer electrolyte fuel cells made from methanol can generate power at relatively low temperatures (100 ° C or lower). It is effective as a power source for vehicles such as automobiles because of its advantages such as high power density, low temperature operation, low deterioration of battery constituent materials, and easy start-up. .

  The basic structure of a solid polymer electrolyte fuel cell consists of two gas diffusion electrodes, a porous cathode (oxygen electrode) and an anode (fuel electrode), using a noble metal such as platinum as a catalyst on both sides of the solid polymer electrolyte membrane. The fuel cell stack is formed by stacking the stacked cells via a separator to form a fuel cell stack, gas passages are formed on both front and back surfaces of each separator, and an oxidizing gas is supplied and discharged to the gas passage on the cathode side, and the anode side In general, the fuel gas is supplied to and exhausted from the gas passage, and since the reaction of the fuel cell is an exothermic reaction, a configuration in which one cooling unit is provided in each of several cells is generally used.

  As a power generator using a solid polymer electrolyte fuel cell having such a configuration, for example, a power generator having a system configuration as shown in FIG. 1 is known. That is, a cell in which both surfaces of the solid polymer electrolyte membrane 1 are sandwiched between the gas diffusion electrodes of the cathode 2 and the anode 3 is laminated with a separator interposed therebetween to form a fuel cell stack, and cooling is performed one by one for several cells. A reformer 5, a heat exchanger 6, a shift converter 7, and a CO remover 8 are sequentially installed from the upstream side on the inlet side of the anode 3 of the solid polymer electrolyte fuel cell I including the section 4, and A methanol supply line 11 is provided so that the supplied methanol is introduced into the reformer 5 through a methanol evaporator 10, while steam from a part of water from a water tank 12 is turned into steam by a steam generator 13. The line 14 is connected to the methanol supply line 11 so that methanol and steam are introduced into the reformer 5 to perform steam reforming, and another part of water is exchanged for cooling. The fuel gas FG reformed in the reformer 5 is cooled by the cooling water from the water tank 12 in the heat exchanger 6 and then operated at 200 ° C. A shift reaction is performed in the shift converter 7 so that the concentration of carbon monoxide (CO), which is a catalyst poison of the solid polymer electrolyte fuel cell I, is reduced to a concentration (1% or less) that can be processed by the CO remover 8. To Further, the fuel gas FG subjected to CO removal processing by the CO remover 8 operated at about 100 to 150 ° C. is supplied to the anode 3 of the solid polymer electrolyte fuel cell I via the humidifier 15.

  On the other hand, at the inlet side of the cathode 2 of the solid polymer electrolyte fuel cell I, air A as an oxidizing gas is compressed by the compressor 17 of the turbocharger 16 and supplied through the humidifier 15 and partially. Is branched into a CO remover 8 to be used for CO combustion, and the entire amount of the cathode exhaust gas CG discharged from the cathode 2 and a part of the anode exhaust gas AG discharged from the anode 3 After being burned in the combustor 19, it is introduced into the combustion chamber of the reformer 5, and the methanol in the reforming chamber of the reformer 5 absorbs heat to 250 ° C. in the presence of the reforming catalyst and reacts. Thus, the fuel gas FG is reformed.

  Further, the exhaust gas discharged from the combustion chamber of the reformer 5 is combusted in the combustor 20 together with a part of the anode exhaust gas AG discharged from the anode 3 and then guided to the turbine 18 to drive the compressor 17. The exhaust gas discharged from the turbine 18 is discharged as an exhaust gas through the steam generator 13 and the methanol evaporator 10. Further, a part of the cooling water from the water tank 12 is allowed to pass through the cooling unit 4 of the solid polymer electrolyte fuel cell I via the humidifier 15, and the cooling water passed through the cooling unit 4 Is cooled by the cooler 21 and put into the water tank 12, and is separated by the steam separator 23 in the cathode exhaust gas line 22 and the steam separator 25 in the anode exhaust gas line 24, respectively. The water is returned to the water tank 12 together with the water that has passed through the heat exchanger 6 and the CO remover 8.

  A hydrogen tank system is also known as a fuel cell, and for example, a system having a system configuration as shown in FIG. 2 is known. In the figure, reference numeral 51 denotes a fuel cell stack in which a fuel electrode 53 and an oxidant electrode 55 are arranged to face each other with a solid polymer electrolyte membrane interposed therebetween, and furthermore, a fuel cell stack is formed by stacking a plurality of layers with the separator interposed therebetween. is there. Reference numeral 57 denotes a humidifier, in which the fuel gas and the oxidizing gas are adjacent to the pure water via the semipermeable membrane, respectively, and the water molecules pass through the semipermeable membrane, so that the fuel gas and the oxidizing gas are separated from each other. Humidification.

  Hydrogen is stored in a hydrogen tank 59, and the hydrogen is regulated by a fuel pressure regulating valve 61, passes through an ejector pump 63, a supply-side water separator 65 and a humidifier 57, and is supplied to the fuel cell stack 51. The fuel is supplied from a fuel inlet 53a of the fuel electrode 53. The mixed gas of hydrogen and steam discharged from the fuel outlet 53b of the fuel electrode 53 passes through the discharge-side water separator 67, the flow path shutoff valve 69, and is mixed with the raw fuel gas by the ejector pumping machine 63, and this mixed gas Is circulated to the fuel electrode 53 of the fuel cell stack 51 via the supply-side water separator 65 and the humidifier 57.

  Further, a purge pipe 75 for purging hydrogen at a purge branch section 73 is branched and connected to a pipe 71 between the discharge-side water separator 67 and the flow path cutoff valve 69, and a purge gas cutoff valve is connected to the purge pipe 75. 77 and a purge gas catalyst 79 are provided respectively.

  The air as the oxidant is supplied from the oxidant inlet 55a to the oxidant electrode 55 of the fuel cell stack 1 through the humidifier 57 by the pump 81. The exhaust gas discharged from the oxidant outlet 55b of the oxidant electrode 55 contains water vapor and liquid water, and the liquid separator 83 separates liquid water. The water separator 83 is provided with an air purge pipe 85 for supplying air during hydrogen purging and a purge gas cutoff valve 87. At the time of hydrogen purging, air is supplied to the purge gas catalyst 79 and discharged to the outside. Further, an air discharge pipe 89 is branched and connected to the air purge pipe 85, and the air discharge pipe 89 is provided with an air pressure regulating valve 91.

  Further, the power generation state of the fuel cell stack 51 is detected by a sensor (not shown), and the hydrogen pressure and the air pressure are adjusted by the fuel pressure control valve 51 and the air pressure control valve 91 in response to the detection signal in response to the detection signal. In addition to performing feedback control, feedback control is performed so that the air flow rate is adjusted by the rotation speed of the compressor 81.

  Further, in the fuel cell system as described above, it is necessary to feed vaporized fuel, fuel gas, high-temperature fuel or compressed air between the devices, and various pumping devices such as a pumping pump and a turbocharger are used. Rolling bearings are often incorporated in the pumps.

  For example, FIG. 3 is a cross-sectional view showing an example of such a pump (impeller type pump). As shown, an impeller 32 is attached to a rotating shaft 31, and the rotating shaft 31 is rolled. It is supported by bearings 33a and 33b. When the impeller 32 rotates at high speed with the rotation of the rotating shaft 31 at high speed, the steam sucked from the steam suction port 34 is pressurized by the centrifugal force of the impeller 32, and the steam formed by the housing 35 and the back plate 36 is formed. The water is pressure-fed from the water vapor discharge port 38 through the pressure volute 37. Further, in this pumping device, when the sealing property of the sealing member 39 decreases, the water vapor passes from the back space 40 on the back surface of the impeller 32 through the gap 41 between the rotating shaft 31 and the sealing member 39, and the rolling bearings 33a, 33b , A baffle 42 and a bush 43 for preventing this are attached to the rotating shaft 31.

  At this time, if the rolling bearings 33a and 33b are lubricated with a lubricating oil, dust generated due to the evaporation of the base oil at high temperatures becomes remarkable, and in some cases, the generated dust adheres to the fuel cell stack. It is feared that it acts as a catalyst poison (see, for example, Patent Document 1).

  As a countermeasure, it has been proposed to prevent the leakage of grease or the like by devising the shape of a holding portion into which the bearing is fitted, with the lubrication of the rolling bearing being grease lubrication (for example, see Patent Document 2). However, this proposal corresponds to the fact that grease does not leak, and there is no idea of suppressing dust generation of grease itself.

Also, in the hydrogen tank type fuel cell system, the rolling bearing incorporated in the ejector pump 63 may cause the same problem.
JP 2000-2192 A JP-A-2002-70764

  The present invention has been made in view of such a situation, and an object of the present invention is to suppress the generation of dust from a rolling bearing by devising grease sealed in a rolling bearing incorporated in a pump of a fuel cell system.

  The present inventors have made intensive studies and found that dust generation can be effectively suppressed by using a low-volatile lubricant as a base oil of grease to be enclosed.

That is, in order to achieve the above object, the present invention provides (1) at least a rolling bearing for a fuel cell which is incorporated in the fuel cell stack and a fuel cell system including the pump for transporting various fluids. Wherein a grease based on a lubricating oil having a vapor pressure of not more than 1.3 × 10 ⁻¹ Pa at 25 ° C. is sealed therein, and (2) at least a rolling bearing for a fuel cell. , A fuel cell rolling bearing incorporated in the fuel cell system of the fuel cell system including a fuel tank, a fuel evaporator, a reformer, a CO removal device, a fuel cell stack, and a pump for transporting various fluids. , to provide a rolling bearing for a fuel cell, wherein the grease vapor pressure at 25 ° C. is a base oil of lubricating oil is less than 1.3 × 10 -1 ^Pa is enclosed .

According to the present invention, a low-dust-generating rolling bearing for a fuel cell can be obtained by enclosing grease using a base oil having a vapor pressure of 1.3 × 10 ⁻¹ Pa or less at 25 ° C.

  Hereinafter, the rolling bearing for a fuel cell of the present invention will be described in detail.

  In the present invention, the configuration itself of the rolling bearing for a fuel cell is not limited, and for example, a ball bearing 300 as shown in FIG. 4 can be exemplified. The illustrated ball bearing 300 holds a plurality of rolling elements, ie, balls 304, between the inner ring 501 and the outer ring 302 via retainers 303 so as to be rotatable at substantially equal intervals. A space S formed by the inner ring 301, the outer ring 302, and the ball 304 is filled with a predetermined amount of grease (not shown) described below, and sealed with a seal 305. The amount of grease to be filled is selected according to the use conditions in the range of 5 to 50% by volume of the bearing space volume as in the conventional case.

(Base oil)
The base oil used for the grease is not particularly limited as long as the vapor pressure at 25 ° C. is 1.3 × 10 ⁻¹ Pa or less, and various lubricating oils can be used. However, when the vapor pressure at 25 ° C. is less than 10 ⁻¹² Pa, the kinematic viscosity of the existing lubricating oil becomes too high, and the torque rise and the heat generation are not preferable. Preferably, it is a lubricating oil having a vapor pressure of 10 ⁻¹⁰ to 10 ⁻² Pa at 25 ° C.

Among the lubricating oils, synthetic lubricating oils are preferable, and in particular, alkyl chain-derived polyphenyl ether oil, alkyl chain-derived naphthalene oil, paraffin hydrocarbon oil, fluorine oil, alkylcyclopentane, and silahydro represented by the following general formula (I) Carbon is preferred.
R1 _n -Si- [R2-Si-R3 _{3] m} ··· (I)
(In the formula, R1, R2, and R3 are alkyl groups, which may be different or may be the same. Further, n = 0 to 2, m = 2 to 4, and n + m = 4.)

More specifically, examples of the alkyl chain-derived polyphenyl ether oil include monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl tetraphenyl ether, dialkyl tetraphenyl ether, and the like. . Examples of the alkyl chain-derived naphthalene oil include monoalkyl naphthalene, dialkyl naphthalene, polyalkyl naphthalene, and the like. Examples of the paraffinic hydrocarbon oil include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly-α-olefin such as 1-decene and ethylene cooligomer, and hydrides thereof. Examples of the fluorine oil include perfluoroether oil, fluorosilicone oil, fluorophosphazene oil and the like. Examples of the alkylcyclopentane include tris (2-octyldodecyl) cyclopentane. The Sila _{hydrocarbon, (n-C 12 H 25} ) 2 Si _{[C 8 H 16 Si (n-} C 12 H 25) 3 ] _2, Si _{[C 3 H 6 Si (n-} C 12 H 25) 3 ] _4, Si _{[C 3 H 6 Si (n-} C 6 H 13) 3 ] _{4, CH} 3 Si _{[CH 2 CH 2 Si (C 6} H 13) 3 ] _{3, CH} 3 Si _[CH 2 _CH 2 Si _(C 8 _{H 17) 3] 3, CH} 3 Si _{[CH 2 CH 2 Si (C 10} H 21) 3 ] _{3, n-C 8 H 17} Si _{[C 3 H 6 Si (n-} C 12 H 25) _{3] 3,} and the like. Further, these lubricating oils can be mixed and used so that the vapor pressure at 25 ° C. becomes 1.3 × 10 ⁻¹ Pa or less.

Furthermore, the base oil consisting of the lubricating oil, preferably a kinematic viscosity at 40 ° C. is 20~400mm ² / ^sec, is less than 20mm 2 / sec (40 ℃) it is difficult to form an oil film, 400 mm ² / When the time exceeds 40 ° C. (40 ° C.), torque and heat generation increase, and in either case, it is not preferable.

Among the above lubricating oils, tris (2-octyldodecyl) cyclopentane has an extremely low vapor pressure of 2.5 × 10 ⁻¹⁰ Pa at 25 ° C. and a kinematic viscosity at 40 ° C. of 112 mm ² / s. This is particularly preferred. Also, the silahydrocarbon has a vapor pressure at 25 ° C. of the order of 10 ⁻¹⁰ Pa, and is therefore preferable.

[Thickener]
There is no particular limitation as long as it has the ability to form a gel structure and retain the base oil in the gel structure, but metal soaps, metal complex soaps and urea compounds are preferred.

  Examples of the metal soap include metal soaps made of Li, Na, and the like, and examples of the metal complex soaps include metal complex soaps made of Li, Na, Ba, Ca, and the like. Examples of the urea compound include a diurea compound, a triurea compound, a tetraurea compound, a polyurea compound, a urea / urethane compound, a diurethane compound, and a mixture thereof. Among them, a diurea compound is more preferable. When a fluoro oil is used as the base oil, a fluoro resin such as polytetrafluoroethylene is used.

  Further, the content of the thickener is preferably 5 to 40% by mass based on the total amount of the grease. If the content of the thickener is less than 5% by mass, sufficient thickening properties cannot be obtained, and the grease is likely to leak, and low dust generation cannot be realized. When the content of the thickener exceeds 40% by mass, the fluidity becomes poor, and there is a possibility that seizure may occur. In addition, since the scattering of the grease is suppressed by increasing the mixing consistency of the grease, it is preferable that the thickener is contained in a larger amount within the above range, and the thickener is 15 to 40% by mass based on the total amount of the grease. Is desirable.

〔Additive〕
Various additives such as antioxidants, rust inhibitors, metal deactivators, oil agents, extreme pressure agents, anti-wear agents, etc. may be used alone or in combination as needed to further enhance lubrication performance, etc. Can be added to the grease. However, since an additive containing a metal element becomes a dust generating source, it is preferable to select an additive containing no metal element except for the metal element as an inevitable impurity. It is preferable that the total amount of these additives be 0.1 to 4% by mass or less of the total amount of grease in consideration of low dust generation.

(Production method)
There is no particular limitation on the method for preparing the grease. However, it is generally obtained by reacting a thickener in a base oil. A kneader or a roll mill can be used for kneading, and additives can be added at the time of kneading.

  The rolling bearing configured as described above is incorporated as rolling bearings 33a and 33b in an impeller-type pumping machine as shown in FIG. 3, and is also used for a scroll-type, swash-plate-type, screw-type, etc. It is used as a rolling bearing that supports each motor spindle.

  FIG. 5 is a side sectional view showing an example of the scroll-type pump. The illustrated scroll type feeder 100 includes a compression mechanism unit 110 including a fixed scroll 111 and an orbiting scroll 112, and a crank mechanism unit that rotates the orbiting scroll 112 by a crankpin 122 a eccentrically provided with respect to a motor main shaft 122. 130 and a drive motor unit 120 for rotating the motor main shaft 122.

  The crank mechanism 130 is provided with a rotation preventing mechanism 132 for preventing the orbiting scroll 112 from rotating. The anti-rotation mechanism 132 includes an Oldham coupling, a pin & ring coupling, and the like in addition to the ball coupling 134 shown in FIG. As the anti-rotation mechanism 132, a crank mechanism using a rolling bearing as disclosed in JP-A-2002-70762 is known, but any of the above-described anti-rotation mechanisms may be employed. .

  The fixed scroll 111 includes a fixed base 111a formed in a disc shape, a spiral swirling spiral part 111c standing upright from the fixed base 111a, and an outer peripheral wall 111b covering the swirling spiral part 111c. The orbiting scroll 112 includes a disc-shaped orbiting base 112b and a spiral orbiting spiral part 112a standing upright from the orbiting base 112b. At the center on the rear side of the swivel base 112b, there is provided a bottomed cylindrical concave portion 112c. A discharge port 114 for air or the like compressed between the fixed scroll 111 and the orbiting scroll 112 is provided substantially at the center of the fixed base 111a in the vertical direction in FIG.

  The needle roller bearing 133 is inserted into the inner peripheral side of the concave portion 112c using the concave portion 112c as a housing. The needle roller bearing 133 rotatably supports the orbiting scroll 112 around the crank pin 122a of the motor main shaft 122 as a rotation axis.

  In the drive motor unit 120, the drive motor 121 includes a rotor 123 fitted on a motor main shaft 122, and a stator 125 provided on the outer peripheral side of the rotor 123 and wound with a coil 124 in the motor housing 101. Become.

  The motor main shaft 122 is rotatably supported by the motor housing 101 via the rolling bearing 102, and is rotatably supported at the rear end (right side in FIG. 5) by the rear housing 104 via the rolling bearing 103. ing. A seal 106 is interposed between the motor main shaft 122 and the motor housing 101 on the crankpin 122a side with respect to the rolling bearing 102, and between the motor housing 101 and the rear housing 104 on the rear side (right end in FIG. 5). Is provided with a seal 107. Further, the motor main shaft 122 is provided with a balance weight 122b, and the balance weight 122b cancels the moment of inertia generated when the orbiting scroll 112 turns, thereby reducing vibration.

  In the scroll-type pumping apparatus 100 configured as described above, when power is supplied to the drive motor 121, the motor main shaft 122 rotates, and the rotation is transmitted to the orbiting scroll 112 via the drive crank mechanism 130. The orbiting scroll 112 orbits while rotating with the rotation of the motor main shaft 122 while meshing with the fixed scroll 111, sucks air or the like into the fixed scroll 111 from a suction port (not shown), and compresses the air with the fixed scroll 111. Let it. Thereafter, compressed air or the like is discharged from the discharge port 114 to the electrode side of the fuel cell.

  Further, a scroll type pump having a configuration shown in FIG. 6 is also known. In the illustrated scroll-type feeder 140, the crank mechanism section 150 includes a drive crank mechanism 151 that causes the orbiting scroll 112 to make a turning motion, and a driven crank mechanism 152 that prevents the orbiting scroll 112 from rotating.

  The driven crank mechanism 152 includes a concave holding portion 112c provided on the orbiting scroll 112, and a rolling bearing 154 that allows the crankpin 153a of the driven crankshaft 153 and the crankpin 153a to rotate with respect to the orbiting scroll 112. The driven crankshaft 153 is rotatably supported by the motor housing 101 via a rolling bearing 155 on the side opposite to the crankpin 153a.

  The driven crankshaft 153 is provided with a balance weight 153b similarly to the motor main shaft 122. The balance weight 153b cancels the moment of inertia generated when the orbiting scroll 112 is turned, thereby reducing vibration. . Other configurations and operations are the same as those of the scroll-type pumping machine 100 shown in FIG. 5, and the same parts are denoted by the same reference numerals.

  FIG. 7 is a side sectional view showing an example of the swash plate type pressure feeder. The illustrated swash plate type pump 160 is of a so-called double swash plate type, and a compression mechanism for compressing a fluid such as air sent to an electrode of a fuel cell by reciprocating of a double-headed piston 172 accompanying rotation of the double-sided inclined plate 171. And a drive motor unit 180 that drives the compression mechanism 170 by rotation of the motor main shaft 182 of the drive motor 181.

  In the compression mechanism 170, the double-headed piston 172 is provided in the crank chamber 163 of the cylinder block 161 so as to be able to reciprocate along the axial direction of the motor main shaft 182, and is connected to the double-sided inclined plate 171 via the shoe 173. ing. The double-sided inclined plate 171 is inserted on the outer peripheral surface of the motor main shaft 182 so as to be rotatable integrally with the motor main shaft 182, and is rotatable via a thrust bearing 174 on a support member 162 provided in the cylinder block 161. It is supported by.

  In the drive motor section 180, the drive motor 181 includes a rotor 183 fitted on the motor main shaft 182 and a stator 185 provided on the outer peripheral side of the rotor 183 and wound with a coil 184 in a motor housing 186. Become.

  The motor main shaft 182 is rotatably supported by the motor housing 186 through a pair of left and right rolling bearings 187 in FIG. 7 from a substantially center in the axial direction, and a right side in FIG. 7, is rotatably supported by a support member 162 via a pair of left and right rolling bearings 175.

  In the double swash plate type pumping device 160 configured as described above, when electric power is supplied to the drive motor 181, the motor main shaft 182 rotates, and the rotation is performed via the double-sided inclined plate 171 and the shoe 173, and the double-headed piston 172 is rotated. Is transmitted to. The double-headed piston 172 reciprocates along the axial direction in the crank chamber 163 with the rotation of the motor main shaft 182, thereby sucking and compressing air and the like and discharging the air and the like to the electrode side of the fuel cell.

  Also, as a swash plate type pump, there is a single swash plate type having a single-sided inclined plate 171a as shown in FIG. The illustrated single swash plate type pump 190 has a configuration in which a piston 177 moves through a rod 176 linked to a single-sided inclined plate 171a, and other components, for example, a support structure of a motor main shaft 182 and a motor The drive unit 180 and the like are the same as those of the double-swash plate type pump 160 shown in FIG. 7, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

  FIG. 9 is a side sectional view showing an example of the screw type pumping machine. The illustrated screw-type pumping device 220 includes a compression mechanism 200 that compresses a fluid such as air sent to the electrode of the fuel cell by rotating the main rotor 201 and the sub-rotor 202 by meshing with each other. And a drive motor unit 180 that drives the compression mechanism unit 200 by rotation of the motor main shaft 182. Note that the drive motor unit 180 is the same as the swash plate type pressure feeder 160 shown in FIG.

  In the compression mechanism 200, the main rotor 201 and the sub-rotor 202 are each formed in a corresponding spiral shape and are rotatable in cooperation with each other by meshing with each other. The main rotor 201 rotatably supports the left rotating shaft 201a in FIG. 9 by the housing 207 via a pair of left and right rolling bearings 203 in FIG. 9, and connects the right rotating shaft 201a to the rolling bearing 204 in FIG. The housing is rotatably supported by the housing. The sub-rotor 202 is rotatably supported by the housing 207 via a pair of left and right rolling bearings 205 in FIG. 8 to support the left rotating shaft 202a in FIG. 9 and the right rotating shaft 202a in FIG. It is rotatably supported by the housing 207 via 206.

  A seal 208 is interposed between the main bearing 201 and the housing 207 on the inner side in the axial direction with respect to the rolling bearings 203 and 204 on the left and right rotating shafts 201a in FIG. A seal 209 is interposed between the sub-rotor 202 and the housing 207 on the inner side in the axial direction of the rolling bearings 205 and 206 on the left and right rotating shafts 202a in FIG.

  The main rotor 201 and the sub-rotor 202 are linked via a connecting gear 210 provided on each of the left rotation shafts 201a and 202a in FIG. A driven gear 211 is provided at the left end of the left rotating shaft 201 a in FIG. 9 of the main rotor 201, and the driven gear 211 is provided with a driving shaft 188 fitted to a motor main shaft 182 of the driving motor 181. It is meshed with the drive gear 189. Therefore, the main rotor 201 transmits the rotation of the motor main shaft 182 via the drive shaft 188, the drive gear 189, and the driven gear 211. The rotation of the main rotor 201 is transmitted to the sub-rotor 202 via the connection gear 210.

  The drive shaft 188 is rotatably supported by the housing 213 via a pair of left and right rolling bearings 212 in FIG. A seal 214 is interposed between the drive shaft 188 and the housing 213.

  In the screw-type pumping device 220 configured as described above, when power is supplied to the drive motor 181, the motor main shaft 182 rotates, and the rotation is mainly performed via the drive shaft 188, the drive gear 189, and the driven gear 211. The power is transmitted to the rotation shaft 201a of the rotor 201. At the same time, the rotation is transmitted from the rotation shaft 201a of the main rotor 201 to the rotation shaft 202a of the sub-rotor 202 via the connection gear 210. The main rotor 201 and the sub-rotor 202 engage and rotate, thereby sucking / compressing air and the like, and discharging the air and the like to the electrode side of the fuel cell.

  Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto.

(Test-1)
Monoalkyltriphenyl ether oil having a kinematic viscosity at 40 ° C of 60 mm ² / sec and a vapor pressure of 1.3 × 10 ⁻⁷ Pa at 25 ° C (“Neovac S-3102” manufactured by Matsumura Petrochemical Laboratories) And a paraffinic hydrocarbon having a kinematic viscosity at 40 ° C. of 45 mm ² / sec and a vapor pressure at 25 ° C. of 2.6 × 10 ⁻⁴ Pa (“Neovac MR-100” manufactured by Matsumura Petrochemical Laboratory Co., Ltd.) And a mineral oil having a kinematic viscosity at 40 ° C. of 5 mm ² / sec and a vapor pressure at 25 ° C. of 1 Pa or more, and the vapor pressure at 25 ° C. is different in a range of 1.3 × 10 ⁻⁷ Pa to 1.0 Pa. A base oil was prepared. Then, lithium 12-hydroxystearate was added to each base oil so as to be 13% by mass of the total amount of the grease, and then dialkyldiphenylemine (an antioxidant) was added so as to be 3% by mass of the total amount of the grease. NLGI consistency No. through a roll mill 2 to obtain a test grease.

The outgassing property of the obtained test grease was evaluated using an outgassing evaluation device shown in FIG. In the evaluation method, first, a petri dish 332 containing 10 mL of test grease 333 is housed in a closed glass container 330 together with a steel plate 331 having a diameter of 63.5 mm, and evacuated by a vacuum pump to maintain a predetermined degree of vacuum. Next, the entirety of the sealed glass container 330 was placed in a thermostat 335, and allowed to stand at 100 ° C. for 10 days. Then, the surface of the steel plate 331 was visually observed to confirm whether or not oil bleeding occurred. The evaluation criteria were as follows, and the evaluation point 2 was regarded as pass.
Evaluation point No oil seepage on steel sheet surface: 2
Slight oil seepage on the steel plate surface: 1
Oil bleeding on steel sheet surface: 0

The above series of operations was performed for each test grease. The results are shown in FIG. 11, and it can be seen that the evaluation points of all test greases using a base oil having a vapor pressure of 1.3 × 10 ⁻¹ Pa or less at 25 ° C. are 2.

(Test-2)
As shown in Table 1, lithium 12-hydroxystearate in tris (2-octyldodecyl) cyclopentane, the monoalkyltriphenyl ether oil used in Test-1 or a paraffinic hydrocarbon accounts for 13% by mass of the total amount of grease. Then, the mixture was heated to completely dissolve lithium 12-hydroxystearate, and then rapidly cooled to obtain a gel. Thereafter, alkyldiphenylamine (antioxidant) was added to the gel so as to be 3% by mass of the total amount of the grease, and the NLGI consistency No. 1 was passed through a three-roll mill. 2 to obtain a test grease.

  And about each test grease, the outgassing property was evaluated using the outgassing evaluation apparatus shown in FIG. The temperature was set to 100 ° C and 140 ° C. The test time is 10 days. The results are also shown in Table 1.

From Table 1, it can be seen that each of the test greases having a base oil having a vapor pressure of 1.3 × 10 ⁻¹ Pa or less at 25 ° C. has an evaluation point of 2 at 100 ° C. and low outgas. In particular, tris (2-octyldodecyl) cyclopentane has an evaluation point of 2 even at a high temperature of 140 ° C., and can realize further lower outgas.

(Test-3)
As shown in Table 2, lithium 12-hydroxystearate was added to the silahydrocarbon so as to be 13% by mass of the total amount of the grease, heated to completely dissolve the lithium 12-hydroxystearate, and then rapidly cooled to obtain a gel. A product was obtained. Thereafter, alkyldiphenylamine (antioxidant) was added to the gel so as to be 3% by mass of the total amount of the grease, and the NLGI consistency No. 1 was passed through a three-roll mill. 2 to obtain a test grease.

  And about each test grease, outgassing property was evaluated like Test-2. The results are also shown in Table 2.

  Table 2 shows that the silahydrocarbon also obtained an evaluation point of 2 even at a high temperature of 140 ° C., indicating that further low outgassing can be realized.

FIG. 1 is a diagram illustrating an entire configuration of an example of a fuel cell system (a solid polymer electrolyte fuel cell). FIG. 9 is a diagram illustrating an overall configuration of another example (a hydrogen tank type fuel cell) of a fuel cell system. It is sectional drawing which shows an example (impeller type | mold pump) of the pump used for a fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one Embodiment of the rolling bearing for fuel cells of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows embodiment which applied the rolling bearing for fuel cells of this invention to a scroll type pump. It is sectional drawing which shows embodiment which applied the rolling bearing for fuel cells of this invention to another scroll type pumping machine. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows embodiment which applied the rolling bearing for fuel cells of this invention to the double swash plate type pump. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows embodiment which applied the rolling bearing for fuel cells of this invention to the swash plate type pump. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows embodiment which applied the rolling bearing for fuel cells of this invention to a screw-type pumping machine. It is a schematic structure figure showing an outgas evaluation device. It is a graph which shows the result of having performed the oil bleeding evaluation changing the vapor pressure of the base oil in an Example.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 solid polymer electrolyte membrane 2 cathode 3 anode 4 cooling unit 5 reformer 6 heat exchanger 7 shift converter 8 CO remover 9 fuel tank 10 methanol evaporator 11 methanol supply line 12 water tank 13 steam generator 14 steam line 15 Humidifier 16 Turbocharger 17 Compressor 18 Turbine 19 Combustor 20 Combustor 21 Cooler 22 Cathode exhaust gas line 23 Steam-water separator 24 Anode exhaust gas line 25 Steam-water separator 31 Rotating shaft 32 Impellers 33a, 33b Rolling bearing 34 Steam inlet 35 Housing 36 Back plate 37 Pressurized volute 38 Water vapor outlet 39 Sealing member 40 Back space 41 Gap 42 Baffle 43 Bush 301 Inner ring 302 Outer ring 303 Cage 304 Ball 305 Seal

Claims (6)

At least a fuel cell rolling bearing for a fuel cell stack and a fuel cell including a pump for transporting various fluids, which is incorporated in the pump of the fuel cell system,
A rolling bearing for a fuel cell, wherein a grease based on a lubricating oil having a vapor pressure of not more than 1.3 × 10 ⁻¹ Pa at 25 ° C. is sealed. At least a rolling bearing for a fuel cell incorporated in the pump of the fuel cell system including a fuel tank, a fuel evaporator, a reformer, a CO removing device, a fuel cell stack, and a pump for transporting various fluids. hand,
A rolling bearing for a fuel cell, wherein a grease based on a lubricating oil having a vapor pressure of not more than 1.3 × 10 ⁻¹ Pa at 25 ° C. is sealed. The rolling bearing for a fuel cell according to claim 1, wherein the rolling bearing is incorporated in an impeller-type pump, a scroll-type pump, a swash-plate-type pump, or a screw-type pump. The base oil is an alkyl chain-derived polyphenyl ether oil, an alkyl chain-derived naphthalene oil, a paraffin-based hydrocarbon oil, a fluorine oil, an alkylcyclopentane, a silahydrocarbon represented by the following general formula (I), or a mixture thereof. The fuel cell rolling bearing according to any one of claims 1 to 3, wherein the rolling bearing is oil.
R1 _n -Si- [R2-Si-R3 _{3] m} ··· (I)
(In the formula, R1, R2, and R3 are alkyl groups, which may be different or may be the same. Further, n = 0 to 2, m = 2 to 4, and n + m = 4.) 5. The rolling bearing for a fuel cell according to claim 4, wherein the base oil is an alkylcyclopentane or a mixed oil thereof. 5. The rolling bearing for a fuel cell according to claim 4, wherein the base oil is a silahydrocarbon or a mixed oil thereof.

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