JP5379741B2 - Cathode gas flow control valve and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow control valve of cathode gas which can maintain a freezing/fixing prevention performance for an extended period. <P>SOLUTION: The flow control valve includes a valve body in which a cathode flow path 42 through which cathode gas flows and a shaft hole which communicates with the cathode flow path 42 are formed, a valve disk that is provided in the cathode flow path 42 and changes an opening area of the cathode flow path 42, and a shaft 46 which is provided by being inserted in the shaft hole to drive the valve. A fluororesin coating layer is formed on the inner peripheral surface of a shaft enclosure part 475 of the shaft hole of the valve body, and a fluororesin composite electroless nickel plating layer is formed on the outer peripheral surface of the shaft 46. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a cathode gas flow control valve and a method for manufacturing the same.

The fuel cell has, for example, a stack structure in which several tens to several hundreds of cells are stacked. Here, each cell is configured by sandwiching a membrane electrode structure (MEA) between a pair of separators. The membrane electrode structure includes two electrodes, an anode electrode (cathode) and a cathode electrode (anode), and these electrodes. And a solid polymer electrolyte membrane sandwiched between the two.
In the fuel cell system, hydrogen gas as an anode gas is supplied to the anode electrode of the fuel cell, and air (air) containing oxygen as the cathode gas is supplied to the cathode electrode, and electric power is generated by an electrochemical reaction. Since only harmless water is generated at the time of power generation, a fuel cell system has attracted attention as a new power source for automobiles from the viewpoint of environmental impact and utilization efficiency.

  In the fuel cell system as described above, the inside of the cathode flow channel through which the cathode gas circulates is wet with the generated water from the fuel cell. The cathode channel is provided with various valves such as a flow rate control valve for controlling the flow rate of the cathode gas and a drain valve for discharging water in the cathode channel. Therefore, conventionally, there has been proposed a technique for preventing various valves provided in the cathode flow path from being frozen and fixed in a low temperature (for example, below freezing point) environment.

  For example, Patent Document 1 discloses a technique for preventing freezing and fixing of a drain valve that discharges water in a cathode channel. In this drain valve, a water repellent coating agent is applied to the surface of a valve body (seal rubber), thereby preventing the valve body and a seat portion on which the valve body is seated from being frozen and fixed.

JP 2008-116042 A

  By the way, the cause of freezing and sticking of the valve is considered to be freezing and fixing of the valve body and its seat part as well as freezing of the shaft that drives the valve body and the shaft hole that accommodates this shaft as in Patent Document 1. It is done. For this reason, a technique has been proposed in which a water-repellent coating agent is applied to the outer peripheral surface of the shaft to prevent icing and sticking between the shaft and the shaft hole.

  However, the coating layer on the outer peripheral surface of the shaft is easily worn or peeled off by rubbing with ice grown from the cathode channel side. Therefore, by repeatedly starting the fuel cell system below freezing point, the water repellent performance of the shaft is lowered, and the performance of preventing the shaft and the shaft hole from being frozen is also lowered.

  In addition, it is conceivable to heat the valve with a heater or a heating device using hot water, regardless of the water-repellent treatment of the valve body or the shaft, in order to deal with such a problem of the icing and fixing of the valve. In addition to being complicated, there is a risk of increasing costs and power consumption.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a cathode gas flow rate control valve that can maintain the anti-freezing property for a long time.

  In order to achieve the above object, the present invention provides a cathode of a fuel cell system (for example, a fuel cell system 1 to be described later) including a fuel cell (for example, a fuel cell 10 to be described later) that generates power by a reaction between an anode gas and a cathode gas. Cathode gas flow control valves (for example, flow control valves 40, 50 described later) provided in flow paths (for example, air supply piping 21 and air discharge piping 22 described later) for controlling the flow rate of the cathode gas. I will provide a. The flow rate control valve is a valve in which a cathode channel (for example, a cathode channel 42 described later) through which a cathode gas flows and a shaft hole (for example, a shaft hole 48 described later) communicating with the cathode channel are formed. A body (for example, a valve body 41 to be described later), a valve body (for example, a valve body 43 to be described later) that is provided in the cathode flow path and changes an opening area of the cathode flow path, and the shaft hole are inserted. And a shaft (for example, a shaft 46 to be described later) that drives the valve body. A fluororesin coating layer is formed on the inner peripheral surface of the shaft hole of the valve body, and a fluororesin composite electroless nickel plating layer is formed on the outer peripheral surface of the shaft.

  In the present invention, the fluororesin coating layer is formed on the inner peripheral surface of the shaft hole portion of the valve body, and the fluororesin composite electroless nickel plating layer is formed on the outer peripheral surface of the shaft inserted through the shaft hole portion. The contact angle of water on the surface on which the fluororesin composite electroless nickel plating layer is formed is approximately 110 to 114 degrees, which is approximately the same as that of the fluororesin coating layer. Thus, it becomes difficult for water to enter the space sandwiched between the water repellent treated surfaces due to capillary action. For this reason, water on the cathode channel side can be prevented from entering the back of the shaft hole through the gap between the inner peripheral surface of the shaft hole and the outer peripheral surface of the shaft. It is possible to prevent the hole from being frozen and fixed. Further, a fluororesin composite electroless nickel plating layer having higher durability than the fluororesin coating layer was formed on the outer peripheral surface of the shaft. As long as the fluororesin composite electroless nickel plating layer is formed after an appropriate pretreatment, it is not easily worn or peeled off as compared with the fluororesin coating layer. Therefore, according to the present invention, since the water repellency performance does not deteriorate even when the fuel cell system is repeatedly started below the freezing point as described above, the performance of preventing the shaft and the shaft hole from freezing and sticking is maintained for a long time. be able to.

  In order to achieve the above object, the present invention provides a cathode of a fuel cell system (for example, a fuel cell system 1 to be described later) including a fuel cell (for example, a fuel cell 10 to be described later) that generates power by a reaction between an anode gas and a cathode gas. Cathode gas flow control valves (for example, flow control valves 40, 50 described later) provided in flow paths (for example, air supply piping 21 and air discharge piping 22 described later) for controlling the flow rate of the cathode gas. A manufacturing method is provided. In this manufacturing method, a valve body in which a cathode channel (for example, a cathode channel 42 described later) through which a cathode gas flows and a shaft hole (for example, a shaft hole 48 described later) communicating with the cathode channel are formed. (For example, a valve body 41 described later) and a shaft (for example, a shaft 46 described later) for driving a valve body (for example, a valve body 43 described later) in the cathode flow path are prepared. Next, in the valve body, a first water repellent treatment (for example, S11 to S17 in FIG. 5 described later) for forming a fluororesin coating layer on the inner peripheral surface of the shaft hole, and the shaft is made of fluororesin By impregnating the nickel plating solution containing particles, a second water repellent treatment (for example, S1 to S9 in FIG. 4 described later) is performed to form a fluororesin composite electroless nickel plating layer on the outer peripheral surface of the shaft. The shaft on which the fluororesin composite electroless nickel plating layer is formed is inserted through the shaft hole in which the fluororesin coating layer is formed.

  In the present invention, the fluororesin coating layer is formed on the inner peripheral surface of the shaft hole by performing the first water repellent treatment, and the fluororesin composite electroless nickel plating is performed on the outer peripheral surface of the shaft by performing the second water repellent treatment. A layer is formed, and a flow control valve is manufactured by inserting a shaft into the shaft hole. Therefore, according to the cathode gas flow rate control valve manufactured according to the present invention, the same effect as the above flow rate control valve can be obtained.

By the way, the coating layer is formed by applying a coating agent to the base material, whereas the electroless nickel plating layer is formed by impregnating the base material with a nickel plating solution.
For this reason, for example, when forming a fluororesin composite electroless nickel plating layer on the inner peripheral surface of the shaft hole portion of the valve body, the portion of the valve body excluding the shaft hole portion is masked, and then the nickel plating solution is used. Need to be impregnated. The valve body to which the valve body and the shaft are assembled has a part that causes inconvenience when a nickel plating layer such as a screw hole or a seal surface is formed, and therefore it is necessary to mask it particularly strictly.
On the other hand, when the fluororesin coating layer is formed on the inner peripheral surface of the shaft hole portion of the valve body as in the present invention, the coating agent is applied after masking only the periphery of the shaft hole portion of the valve body. Good. Since the masking required at this time is only required around the shaft hole portion, it can be simplified as compared with the case where the nickel plating solution is impregnated as described above.
Therefore, according to the present invention, it is possible to reduce the manufacturing cost while producing substantially the same effect as in the case where the fluororesin composite electroless nickel plating layer is formed on both the valve body and the shaft.

It is a figure showing typically composition of a fuel cell system to which a flow control valve concerning one embodiment of the present invention is applied. It is a fragmentary sectional view showing the composition of the flow control valve concerning the above-mentioned embodiment. It is a fragmentary sectional view which shows the structure of the shaft surrounding part and shaft which concern on the said embodiment. It is a figure which shows the procedure which forms a fluororesin composite electroless nickel plating layer in the outer peripheral surface of the shaft which concerns on the said embodiment. It is a figure which shows the procedure which forms a fluororesin coating layer in the internal peripheral surface of the shaft hole part of the valve body which concerns on the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system 1 to which a cathode gas flow control valve according to an embodiment of the present invention is applied.
The fuel cell system 1 is mounted on an automobile and generates a power by reacting a reaction gas, a supply device 20 that supplies and discharges hydrogen gas and air (air) to the fuel cell 10, and these fuel cells. 10 and a control device 30 for controlling the supply device 20. The fuel cell 10 generates electricity by an electrochemical reaction when hydrogen gas as an anode gas is supplied to the anode electrode (cathode) side and air containing oxygen as the cathode gas is supplied to the cathode electrode (anode) side.

The supply device 20 includes an air pump 24 that generates compressed air, an air supply pipe 21 that is connected to the fuel cell 10 and supplies air compressed by the air pump 24 to the cathode electrode side, and is connected to the fuel cell 10 from the cathode electrode side. An air discharge pipe 22 for discharging air. In addition, the supply device 20 includes a hydrogen supply pipe (not shown) that supplies hydrogen gas to the anode electrode side of the fuel cell 10 and a hydrogen discharge pipe (not shown) that discharges hydrogen gas from the anode electrode side of the fuel cell 10. .
The air supply pipe 21 and the air discharge pipe 22 are provided with a humidifier 23. The humidifier 23 collects moisture contained in the air flowing through the air discharge pipe 22 and adds the collected moisture to the air flowing through the air supply pipe 21.

  Flow control valves 40 and 50 for controlling the flow rate of air are provided between the fuel cell 10 and the humidifier 23 in the air supply pipe 21 and the air discharge pipe 22 through which air flows. These flow control valves 40 and 50 are connected to the control device 30 via actuators (not shown), and their opening degrees are controlled according to a control signal transmitted from the control device 30.

  Hereinafter, a detailed configuration of the outlet-side flow control valve 40 provided in the air discharge pipe 22 will be described. Note that the configuration of the inlet-side flow control valve 50 provided in the air supply pipe 21 is substantially the same as that of the outlet-side flow control valve 40, and therefore detailed description thereof is omitted.

FIG. 2 is a cross-sectional view of the flow control valve 40.
The flow control valve 40 includes a valve body 41 in which a cathode channel 42 through which air flows is formed, a disc-shaped valve body 43, and a shaft 46 that rotates the valve body 43. The flow rate control valve 40 controls the flow rate of air flowing through the cathode channel 42 by rotating a valve body 43 provided in the cathode channel 42 with a shaft 46 to change the opening area of the cathode channel 42. This is a so-called butterfly valve.

  A linear cathode channel 42 is formed in the approximate center of the valve body 41. Further, on both sides of the valve body 41 with the cathode channel 42 interposed therebetween, shaft hole portions 47 and 48 extending substantially perpendicular to the extending direction of the cathode channel 42 and communicating with the cathode channel 42 are formed. ing.

  The shaft 46 is inserted into the shaft hole portions 47 and 48 and is rotatable in the shaft hole portions 47 and 48. Further, a valve body 43 is attached to a shaft 46 inserted through the shaft hole portions 47 and 48 by screws 461. As a result, the shaft 46 is rotated by an electromagnetic actuator (not shown), and the angle of the valve body 43 with respect to the cathode flow path 42 and thus the opening area of the cathode flow path 42 can be changed.

  A stepped portion 471 is formed on the inner peripheral surface of the shaft hole 47 along the circumferential direction. The step portion 471 includes a lip seal 472 that prevents air in the cathode channel 42 from flowing out of the valve body 41 along the outer peripheral surface of the shaft 46, and a collar member 473 that holds the lip seal 472. A bearing 474 that rotatably supports the shaft 46 in the shaft hole 47 is fitted in this order from the cathode channel 42 side toward the outside. A portion of the shaft hole 47 closer to the cathode channel 42 than the stepped portion 471 is a shaft surrounding portion 475 that surrounds the outer peripheral surface of the shaft 46 through a predetermined gap.

  A stepped portion 481 is similarly formed on the inner peripheral surface of the shaft hole portion 48, and a lip seal 482, a collar member 483, and a bearing 484 are provided on the stepped portion 481 from the cathode channel 42 side to the outside. They are fitted in this order. A portion of the shaft hole 48 closer to the cathode channel 42 than the stepped portion 481 is a shaft surrounding portion 485 that surrounds the outer peripheral surface of the shaft 46 through a predetermined gap.

In the valve body 41 and the shaft 46 configured as described above, water droplets in the cathode flow path 42 travel along the gap between the outer peripheral surface of the shaft 46 and the inner peripheral surfaces of the shaft surrounding portions 475 and 485. In order to prevent leakage to the outside of the body 41, water repellent treatment is performed. More specifically, a fluororesin coating layer is formed on the inner peripheral surfaces of the shaft surrounding portions 475 and 485 of the shaft hole portions 47 and 48, and the fluororesin composite electroless nickel is formed on the outer peripheral surface of the shaft 46. A plating layer is formed.
The surface of the fluororesin coating layer and the fluororesin composite electroless nickel plating layer has a water contact angle of about 110 to 114 degrees and a high water repellent effect. In the space sandwiched between the surfaces subjected to such water repellent treatment, it is difficult for water to enter due to a capillary phenomenon, so that water on the cathode channel 42 side is outside the valve body 41 through the gap. Leakage can be prevented.

  FIG. 3 is a partial cross-sectional view showing the configuration of the shaft surrounding portion 475 of the shaft hole and the shaft 46 when the shaft 46 is assembled to the valve body. Below, although the case where the shaft 46 whose diameter is 8 [mm] is used is demonstrated, this invention is not limited to this.

  The inner diameter of the shaft surrounding portion 475 is formed such that the gap between the inner peripheral surface thereof and the outer peripheral surface of the shaft 46 is 0.1 [mm] or less. Further, as shown in FIG. 3, a fluororesin coating layer is formed in a region facing the outer peripheral surface of the shaft 46 in the inner peripheral surface of the shaft surrounding portion 475.

  On the other hand, on the outer peripheral surface of the shaft 46, as shown in FIG. 3, when the shaft 46 is assembled to the valve body, an area exposed in the cathode flow path 42 (hereinafter referred to as “exposed area”) and a shaft surrounding portion A fluororesin composite electroless nickel plating layer is formed over both the region overlapping with 475 (hereinafter referred to as “overlapping region”).

The length along the axial direction of the plating layer in the overlapping region is assumed when one water droplet spreads along the outer peripheral surface of the shaft 46 with a uniform thickness, and this spread water is separated from the shaft surrounding portion 475 and the shaft. It is set so that it can be surely excluded from the gap of 46. More specifically, the length along the axial direction of the plating layer in the overlapping region is such that the volume of the gap between the plating layer on the outer peripheral surface of the shaft 46 and the coating layer of the shaft surrounding portion 475 is equivalent to one water droplet. Set to be larger than volume. For example, when the diameter of the water droplet is 2 [mm], the diameter of the shaft 46 is 8 [mm], and the gap between the shaft surrounding portion 475 and the shaft 46 is 0.1 [mm], the volume of the water droplet (about 4 mm). .189 [mm ³ ]) in order to secure a gap having a volume larger than that, the length along the axial direction of the plating layer in the overlapping region is set to 1.646 [mm] or more, for example, 2 [mm]. That's fine.
In addition, when the diameter of the shaft 46 is increased while the gap between the shaft surrounding portion 475 and the shaft 46 is made constant, the volume of the gap per unit length along the axial direction is increased, so that the axial direction of the plating layer is increased. The length along it can also be shortened.

On the other hand, the length along the axial direction of the plating layer in the exposed region is set to be longer than the width of water droplets (for example, 4 [mm]) on the surface where the plating layer is not formed.
As shown in FIG. 3, since the contact angle of water on the surface where the plating layer is not formed is smaller than the surface where the plating layer is formed, the height of the top of the water droplet is reduced and the width along the axial direction is reduced. growing. Thus, in order to efficiently prevent water droplets spreading along the surface from entering the gap between the shaft surrounding portion 475 and the shaft 46 from the cathode channel 42 side, the plating layer is formed as described above. It is preferable to form a plating layer longer than the width of the water droplet on the surface not formed in the exposed region.

  Although detailed description is omitted, the same water-repellent treatment is performed on the shaft surrounding portion 485 and the portion of the shaft 46 on the shaft surrounding portion 485 side.

Hereinafter, a specific manufacturing method of the flow control valve will be described with reference to FIGS. 4 and 5.
FIG. 4 is a diagram showing a procedure for forming a fluororesin composite electroless nickel plating layer on the outer peripheral surface of the shaft. Here, a specific procedure when a stainless steel material is used as the material of the shaft will be described. In addition, when forming an electroless nickel plating layer on a stainless steel material, in order to improve the adhesion of the nickel plating to the base material and prevent the plating layer from peeling off, a nickel strike treatment is performed to remove the oxide film as a pretreatment. It is preferable to apply (see S3 described later).

First, the entire surface of the throttle shaft is washed with a degreasing liquid and then dried (S1). A masking tape is applied to the non-plated surface of the dried throttle shaft where no plating layer is formed (S2), and this is impregnated with a nickel strike treatment liquid (for example, nickel hydrochloride) (S3, nickel strike treatment). . After the nickel strike process is completed, the masking tape attached in S2 is peeled off, and the entire surface is washed (S4) and dried (S5).
Next, a masking tape is applied to the non-plated surface of the dried throttle shaft (S6), and this is impregnated with an electroless nickel plating solution containing fluorine resin particles (S7, fluorine resin composite electroless nickel plating treatment). ). Here, since the plating solution is alkaline, it is preferable to use a masking tape (for example, butyl rubber self-bonding tape) using an alkali-resistant adhesive. After the fluororesin composite electroless nickel plating process is completed, the masking tape attached in S6 is peeled off, and then the entire surface is washed (S8) and dried (S9).

FIG. 5 is a diagram showing a procedure for forming a fluororesin coating layer on the inner peripheral surface of the shaft hole of the valve body.
First, the entire surface of the throttle body is washed with a degreasing liquid and then dried (S11). A masking tape is affixed to the non-coating process surface which does not form a fluororesin coating layer among the dried throttle bodies (S12). Here, unlike the above-mentioned fluororesin composite electroless nickel plating, the region where the masking tape is applied does not have to be the entire surface of the non-coating treatment surface, and may be only around the shaft hole where the coating layer is formed. Next, a fluororesin coating agent is sprayed and painted on the inner peripheral surface of the shaft hole in the throttle body (S13, fluororesin coating process). Next, the fluororesin-coated throttle body is dried (S14), the masking tape attached in S12 is removed (S15), fired for a predetermined time (S16), and naturally cooled (S17). .
The flow control valve is inserted into the shaft hole of the valve body that has been subjected to the water repellent treatment in the above procedure through the shaft that has been subjected to the water repellent treatment in accordance with the procedure shown in FIG. Manufactured by assembling seals, collar members and bearings.

According to this embodiment, the following effects can be obtained.
(1) In this embodiment, a fluororesin coating layer is formed on the inner peripheral surface of the shaft hole 47 of the valve body 41, and the fluororesin composite electroless nickel is formed on the outer peripheral surface of the shaft 46 inserted through the shaft hole 47. A plating layer was formed. Thereby, it is possible to prevent the water on the cathode channel 42 side from entering the back of the shaft hole 47 through the gap between the inner peripheral surface of the shaft hole 47 and the outer peripheral surface of the shaft 46. Therefore, it is possible to prevent the shaft 46 and the shaft hole 47 from being frozen and fixed. In this embodiment, a fluororesin composite electroless nickel plating layer having higher durability than the fluororesin coating layer is formed on the outer peripheral surface of the shaft 46. As long as the fluororesin composite electroless nickel plating layer is formed after an appropriate pretreatment, it is not easily worn or peeled off as compared with the fluororesin coating layer. Therefore, even if the fuel cell system 1 is repeatedly started below the freezing point, the water repellency performance does not deteriorate, so that the performance of preventing the shaft 46 and the shaft hole 47 from being frozen can be maintained for a long time.

  (2) In this embodiment, a fluororesin coating layer is formed on the inner peripheral surface of the shaft hole 47 of the valve body 41. For this reason, masking can be simplified compared with the case where the fluororesin composite electroless nickel plating process which needs to impregnate a base material in a plating solution is performed. Therefore, compared with the case where the fluororesin composite electroless nickel plating layer is formed on both the valve body 41 and the shaft 46, it is possible to reduce the manufacturing cost while producing substantially the same effect.

  In the said embodiment, although the butterfly valve which changes the opening area of a cathode flow path with a disk shaped valve body was demonstrated to the example, this invention is not limited to this. The present invention can also be applied to a ball valve that changes the opening area of the cathode channel with a spherical valve body.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system 10 ... Fuel cell 21 ... Air supply piping 22 ... Air discharge piping 40, 50 ... Flow control valve 41 ... Valve body 42 ... Cathode flow path 43 ... Valve body 46 ... Shaft 47 ... Shaft hole 475 ... Shaft Go part 48 ... Shaft hole 485 ... Shaft part

Claims (2)

A cathode gas flow rate control valve for controlling the flow rate of cathode gas, provided in a flow path through which cathode gas circulates in a fuel cell system including a fuel cell that generates power by reaction of anode gas and cathode gas,
The flow control valve is
A valve body in which a cathode channel through which cathode gas flows and a shaft hole communicating with the cathode channel are formed;
A valve body provided in the cathode flow path and changing an opening area of the cathode flow path;
A shaft that is inserted through the shaft hole and drives the valve body, and
A fluorine resin coating layer is formed on the inner peripheral surface of the shaft hole of the valve body,
A cathode gas flow control valve, wherein a fluororesin composite electroless nickel plating layer is formed on an outer peripheral surface of the shaft. A method for manufacturing a cathode gas flow rate control valve for controlling a cathode gas flow rate provided in a flow path through which a cathode gas flows in a fuel cell system including a fuel cell that generates electricity by a reaction between an anode gas and a cathode gas. ,
A valve body in which a cathode channel through which cathode gas flows and a shaft hole communicating with the cathode channel are formed;
A shaft for driving a valve body in the cathode flow path,
A first water-repellent treatment for forming a fluororesin coating layer on the inner peripheral surface of the shaft hole in the valve body, and the shaft is impregnated with a nickel plating solution containing fluororesin particles. Performing a second water repellent treatment to form a fluororesin composite electroless nickel plating layer on the outer peripheral surface of
A method of manufacturing a cathode gas flow rate control valve, wherein a shaft having the fluororesin composite electroless nickel plating layer is inserted into a shaft hole portion in which the fluororesin coating layer is formed.

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