JP4666225B2 - Overflow prevention valve - Google Patents

Description

  The present invention relates to an overflow prevention valve in which a valve body moves against a biasing force of a valve body spring and closes when the flow rate of fuel gas supplied to the valve body exceeds a predetermined value. It relates to the improvement of its operating characteristics.

  For example, a fuel cell vehicle that drives a traveling motor with power generated by a fuel cell that generates electricity by an electrochemical reaction between fuel gas and oxidizing gas, or a natural gas (CNG) burned by an internal combustion engine to generate driving force for traveling. In a directly obtained natural gas vehicle or the like, an overflow prevention valve that automatically prevents overflow of the fuel gas is provided in the discharge passage of the fuel gas tank in order to prevent overflow of the fuel gas from the fuel gas tank. become.

When the pressure on the secondary side (downstream side) falls below the normal range, this overflow prevention valve is attached to the valve body spring by the differential pressure between the primary side (upstream side) and the secondary side. The flow path is closed by moving against the force and seating on the valve seat (see, for example, Patent Document 1).
JP 2002-310314 A

  In the conventional overflow prevention valve, the valve body spring has a structure that keeps the distance between the valve body and the valve seat constant regardless of the primary pressure level. Therefore, as shown by X in FIG. As the value increases, the mass flow rate at the time of closing operation increases, and there is a closing operation characteristic. In other words, although the volume flow rate of the fuel gas passing through the gap between the valve body and the valve seat is substantially constant regardless of the primary pressure level, the higher the primary pressure, the higher the density of the fuel gas. The mass flow rate during the closing operation becomes high.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an overflow prevention valve capable of suppressing the variation of the closed operation characteristic with respect to the mass flow rate caused by the level of the primary pressure.

  In order to achieve the above object, the overflow prevention valve according to the present invention is such that the valve body supported by the pedestal via the valve body spring moves against the biasing force of the valve body spring and is seated on the valve seat. Thus, the overflow prevention valve closes the flow path, and the relative position of the pedestal with respect to the valve seat can be adjusted by the primary pressure on the upstream side.

  According to this configuration, since the relative position of the pedestal with respect to the valve seat can be adjusted by the upstream primary pressure, the clearance between the valve body supported by the pedestal via the valve body spring and the valve seat is reduced in the primary pressure level. It can be made variable according to. Therefore, it is possible to suppress the variation in the closing operation characteristic with respect to the mass flow rate caused by the primary pressure level.

  In this case, the pedestal is movable and has a primary pressure receiving portion that receives the primary pressure in a direction in which the support portion of the valve body spring is separated from the valve seat, and the pedestal receives the primary pressure. It is preferable to provide a pedestal spring that biases in the direction opposite to the direction.

  According to this configuration, when the upstream primary pressure is high, the pedestal moves in a direction to separate the support portion of the valve body spring from the valve seat against the biasing force of the pedestal spring, and the valve body spring is moved to the support portion. The gap between the valve body and the valve seat supported via the gap is reduced. Further, when the upstream primary pressure is low, the pedestal does not move in the direction of separating the support portion of the valve body spring from the valve seat, and the gap between the valve body and the valve seat is increased. Therefore, when the primary pressure is high, the increase in mass flow rate can be suppressed by reducing the volume flow rate by narrowing the gap between the valve body and the valve seat. Can be suppressed.

  In this case, it is preferable that the pedestal includes an atmospheric pressure receiving portion that receives atmospheric pressure in a direction opposite to the pressure receiving direction of the primary pressure.

  According to this configuration, since the pedestal receives the atmospheric pressure in the direction opposite to the primary pressure receiving direction at the atmospheric pressure receiving portion, the influence of the secondary pressure, that is, downstream operation as in the case of receiving the secondary pressure. The position of the pedestal can be adjusted while suppressing the influence of the situation.

  According to the present invention, it is possible to suppress the variation of the closed operation characteristic with respect to the mass flow rate caused by the primary pressure level.

  Next, a first embodiment of the overflow prevention valve according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a vehicle 1 equipped with a gas tank. This vehicle 1 equipped with a gas tank is a four-wheeled vehicle having four traveling wheels 3 on a vehicle body 2 and receives power from reaction gas (oxidizing gas and fuel gas). The vehicle body 2 includes a fuel cell system (driving means) 10 that generates the power and a travel motor (driving means) 11 that drives, for example, the front wheels 3 with the power generated by the fuel cell system 10. In FIG. 1, the front of the vehicle 1 is indicated by an arrow Fr, and the rear of the vehicle 1 is indicated by an arrow Rr.

  The fuel cell system 10 includes a fuel cell stack 12 that generates power by receiving supply of reaction gases (oxidizing gas and fuel gas) in the vehicle body 2, and supplies gas to the fuel cell stack 12 with air as an oxidizing gas. And an oxidizing gas piping system 13 for adjusting the supply of hydrogen gas as a fuel gas.

  The fuel gas piping system 14 includes a plurality, specifically, four fuel gas tanks 20a to 20d that can store high-pressure (for example, 35 to 70 MPa) fuel gas, respectively. These fuel gas tanks 20 a to 20 d are mounted on the vehicle body 2.

  All the fuel gas tanks 20a to 20d mounted on the vehicle as described above are provided with discharge ports for discharging the fuel gas, and these discharge ports have individual discharge flow paths 22a to 22 for discharging the fuel gas in the fuel gas tanks 20a to 20d. 22d is connected. These discharge channels 22 a to 22 d have the same channel cross-sectional area, are connected to a common supply channel 23, and communicate with the fuel cell stack 12 through the supply channel 23.

  All the fuel gas tanks 20a to 20d are internally provided with main stop valves 24a to 24d that are controlled by the control device 15 to switch between supply and stop of supply of fuel gas to the connected discharge passages 22a to 22d. It has been. Further, the supply flow path 23 is provided with a pressure sensor 25 at a position downstream of all the fuel gas tanks 20 a to 20 d, and a pressure reducing valve 26 is provided downstream of the pressure sensor 25.

  Although not shown, the control device 15 is connected to various sensors including a pedal sensor that detects the opening degree of an accelerator pedal that is operated by a driver. The pedal opening degree and pressure sensor 25 that are detected by the pedal sensor. The main stop valves 24a to 24d are controlled based on the detection signals of the plurality of sensors including the supply pressure detected by the control, and the fuel gas supply from the fuel gas tanks 20a to 20d to the fuel cell stack 12 is controlled.

  Then, the pressure on the secondary side (downstream side, that is, the fuel cell stack side) with respect to the pressure on the primary side (upstream side, that is, the fuel gas tank side) is set in each of the discharge flow paths 22a to 22d for all the fuel gas tanks 20a to 20d. When the pressure difference decreases and the differential pressure increases, mechanically closed overflow prevention valves (EFV: Excess flow valves) 27a to 27d of the first embodiment are provided.

  Since these overflow prevention valves 27a to 27d are the same, the overflow prevention valve 27a will be described as an example with reference to FIG.

  The overflow prevention valve 27a has a casing 31 that constitutes an outer portion thereof, and a first hole portion 32 is formed in the casing 31 on the communication side (left side in FIG. 2) to the fuel gas tank 20a. A second hole 33 having a smaller diameter than the first hole 32 is formed on the opposite side of the first hole 32 from the fuel gas tank 20a.

  The casing 31 is formed with a third hole 34 having a smaller diameter than the second hole 33 on the side opposite to the first hole 32 of the second hole 33. A fourth hole 35 having a diameter larger than that of the third hole 34 is formed on the side opposite to the second hole 33 of 34.

  Further, the casing 31 is formed with a fifth hole portion 36 having a smaller diameter than the fourth hole portion 35 and communicating with the fuel cell stack 12 on the opposite side of the fourth hole portion 35 from the third hole portion 34. Yes. Here, the first hole portion 32 to the fifth hole portion 36 are formed on the same axis.

  In addition, a cylindrical housing space 38 concentric with the first hole portion 32 to the fifth hole portion 36 is formed outside the casing 31 so as to surround the fourth hole portion 35. The intermediate portion in the axial direction of the portion 35 and the accommodation space portion 38 communicates with the communication space portion 39 over the entire circumference. Further, the casing 31 is formed with a branch channel 41 for communicating the end face on the first hole portion 32 side in the axial direction of the accommodation space portion 38 with the first hole portion 32. Circular seal grooves 42 and 43 are formed on the inner diameter sides on both sides of the communication space 39 in the axial direction. In addition, an atmospheric pressure port 44 that is open to the atmosphere is formed in the casing 31 on the fifth hole 36 side of the accommodation space 38.

  The overflow prevention valve 27a has an annular seat member 46 fitted to the inner peripheral surface of the second hole portion 33. The seat member 46 includes an inner seat on the first hole portion 32 side. A valve seat 47 chamfered on the circumferential side is formed.

  The overflow prevention valve 27a has a pedestal 49 that is slidably provided in the casing 31 described above. The pedestal 49 has a cylindrical sliding base portion 50 slidably provided in the accommodation space portion 38 of the casing 31, and extends in an annular shape inward from an axially intermediate portion of the sliding base portion 50 to mainly communicate with the space. And an inner flange portion 51 disposed in the portion 39, and the inner peripheral portion of the inner flange portion 51 extends into the fourth hole portion 35. An annular seal groove 52 is formed on the outer peripheral surface of the slide base portion 50 of the pedestal 49.

  Here, in the seal groove 42 on the first hole 32 side of the casing 31, a seal ring 53 that always seals the gap with the pedestal 49 regardless of the sliding position of the pedestal 49 is disposed. A seal ring 54 that always seals the gap with the pedestal 49 regardless of the sliding position of the pedestal 49 is also provided in the seal groove 43 of the pedestal 49. A seal ring 55 for sealing the gap is provided.

  In addition, the overflow prevention valve 27 a is a coil that is interposed in the housing space 38 of the casing 31 between the end surface on the fifth hole 36 side in the axial direction and the sliding base portion 50 of the pedestal 49. A base spring 58 made of a spring is provided. This base spring 58 biases the base 49 toward the first hole 32 in the axial direction.

  Further, the overflow prevention valve 27a is fixed at one end side to the support portion 60 on the inner peripheral side of the inner flange portion 51 of the base 49, and the other end side passes through the inside of the seat member 46 and extends to the first hole portion 32 side. And a spherical valve body 62 fixed to the other end side of the valve body spring 61 in the first hole portion 32.

  The overflow prevention valve 27a having such a structure is disposed in the discharge flow path 22a with the first hole 32 of the casing 31 facing the fuel gas tank 20a and the fifth hole 36 facing the fuel cell stack 12 side. It will be. In this state, the overflow prevention valve 27a is configured such that the valve body 62 supported by the base 49 via the valve body spring 61 moves against the urging force of the valve body spring 61 and is seated on the valve seat 47. The flow path is closed.

  At this time, the primary pressure acts on the end surface of the sliding base portion 50 of the pedestal 49 on the first hole portion 32 side via the branch channel 41 so as to move the pedestal 49 in the direction of the pedestal spring 58. As a result, this end surface serves as a primary pressure receiving portion 63 that receives a primary pressure in a direction in which the support portion 60 of the valve body spring 61 is separated from the valve seat 47.

  Further, the end surface of the pedestal 49 opposite to the primary pressure receiving portion 63 of the sliding base portion 50 is an atmospheric pressure receiving portion 64 that receives atmospheric pressure in the direction opposite to the primary pressure receiving direction. The pedestal spring 58 biases the pedestal 49 in the direction opposite to the primary pressure receiving direction.

  According to the overflow prevention valve 27a having the above structure, the relative position of the pedestal 49 with respect to the valve seat 47 can be adjusted by the primary pressure on the upstream side. Therefore, the valve body supported by the pedestal 49 via the valve body spring 61. The clearance between the valve 62 and the valve seat 47 can be made variable according to the level of the primary pressure.

  Specifically, when the upstream primary pressure is high, the pedestal 49 resists the urging force of the pedestal spring 58 by the pressure applied to the primary pressure receiving portion 63 via the branch flow path 41 as shown in FIG. The support portion 60 is moved away from the valve seat 47, and the valve body 62 supported by the support portion 60 via the valve body spring 61 is moved to the downstream side along the axial direction so that the valve body 62 is moved. And the clearance between the valve seat 47 and the valve seat 47 are reduced.

  If the primary pressure on the upstream side is low, the pedestal 49 does not move by the urging force of the pedestal spring 58 even when pressure is applied to the primary pressure receiving portion 63 via the branch flow path 41, and the valve body 62 and the valve seat The gap with 47 is increased. Therefore, when the primary pressure is high, an increase in the mass flow rate can be suppressed by narrowing the gap between the valve body 62 and the valve seat 47 to reduce the volume flow rate. Therefore, as shown by X1 in FIG. The fluctuation of the closed operation characteristic with respect to the mass flow rate caused by the height can be suppressed and can be controlled to be constant.

  Moreover, since the pedestal 49 receives the atmospheric pressure in the direction opposite to the primary pressure receiving direction at the atmospheric pressure receiving portion 64, the influence of the secondary pressure as in the case of receiving the secondary pressure, that is, the downstream fuel cell stack. The position of the pedestal 49 can be adjusted while suppressing the influence of the 12 driving situations.

  In the above description, the position of the valve seat 47 is fixed and the pedestal 49 can be moved according to the primary pressure. However, it is sufficient that the relative position of the pedestal 49 with respect to the valve seat 47 can be adjusted by the upstream primary pressure. It is also possible to move the valve seat 47 according to the primary pressure while fixing the position 49.

  Next, a second embodiment of the overflow prevention valve according to the present invention will be described with reference to FIG. 4 focusing on the differences from the first embodiment. In addition, the same code | symbol is attached | subjected to the part similar to 1st Embodiment, and the description is abbreviate | omitted.

  Also in the second embodiment, since the overflow prevention valves 27a to 27d are the same, the overflow prevention valve 27a will be described as an example.

  In the overflow prevention valve 27a of the second embodiment, the casing 31 does not have the first atmospheric pressure port 44, and the seal groove 43 and the seal ring 54 on the fifth hole 36 side of the accommodation space 38 are provided. I don't have it. Therefore, the end surface opposite to the primary pressure receiving portion 63 of the pedestal 49 is a secondary pressure receiving portion 65 that receives the downstream secondary pressure in the direction opposite to the primary pressure receiving direction.

  In the second embodiment as well, similarly to the first embodiment, it is possible to suppress the variation of the closed operation characteristic with respect to the mass flow rate caused by the level of the primary pressure. In addition, the atmospheric pressure port, the seal ring, and the Since the sealing groove can be reduced, the manufacturing cost and the number of parts can be reduced.

  In the above description, the fuel cell system 10 that generates power by the electrochemical reaction between the fuel gas and the oxidizing gas is described, and the fuel cell vehicle that drives the traveling motor 11 with the generated power is described as an example. The present invention can also be applied to vehicles equipped with various fuel gas tanks such as a natural gas vehicle in which CNG) is burned by an internal combustion engine to directly obtain a driving force for traveling. Of course, the present invention is not limited to a vehicle equipped with a fuel gas tank but can be applied to other various fluid circuits.

It is a lineblock diagram of a gas tank loading vehicle to which an overflow prevention valve concerning a 1st embodiment of the present invention is applied. It is sectional drawing of the overflow prevention valve which concerns on 1st Embodiment of this invention. It is a characteristic diagram which shows the closing operation characteristic of the overflow prevention valve which concerns on 1st Embodiment of this invention. It is sectional drawing of the overflow prevention valve which concerns on 2nd Embodiment of this invention. It is a characteristic diagram which shows the closing operation characteristic of an overflow prevention valve.

Explanation of symbols

  27a-27d ... Overflow prevention valve, 49 ... Base, 58 ... Base spring, 60 ... Supporting part, 61 ... Valve body spring, 62 ... Valve body, 63 ... Primary pressure receiving part, 64 ... Atmospheric pressure receiving part.

Claims (3)

An overflow prevention valve that closes the flow path by the valve body supported by the pedestal via the valve body spring moving against the urging force of the valve body spring and seating on the valve seat,
The overflow prevention valve which enabled adjustment of the relative position with respect to the said valve seat with the primary pressure upstream. The overflow prevention valve according to claim 1,
The pedestal is movable and has a primary pressure receiving portion that receives the primary pressure in a direction in which a support portion of the valve body spring is separated from the valve seat;
An overflow prevention valve provided with a pedestal spring that biases the pedestal in a direction opposite to the pressure receiving direction of the primary pressure. The overflow prevention valve according to claim 2,
The overflow prevention valve in which the said base is provided with the atmospheric pressure receiving part which receives atmospheric pressure in the direction opposite to the pressure receiving direction of the said primary pressure.

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