JP4803813B2 - In-vehicle gas detector - Google Patents

Description

  The present invention relates to a vehicle-mounted gas detection device that detects hydrogen leakage in a fuel cell vehicle or the like, or detects outside air contamination in order to switch the air supply to the vehicle compartment between outside air introduction and inside air circulation.

There is known a vehicle-mounted gas detection device in which a gas sensor is accommodated in an opening provided in a case and an atmosphere is introduced through a water repellent film such as a PTFE film. In-vehicle gas detectors are required to prevent water droplets and dust from touching the gas sensor and to have a quick response to changes in the atmosphere. Patent Document 1 discloses that a gas introduction hole is provided in a leg of a cap that covers the opening of the case, and the gas is guided to the PTFE film at the upper portion of the opening using a gap between the cap and the case as a gas passage. However, in this gas detection device, there is a problem that when the cap is used, water accumulated between the cap and the case cannot be removed, and there is no mechanism for keeping the height of the cap constant with respect to the case.
Patent 3743718

  The subject of this invention is providing the vehicle-mounted gas detection apparatus which can make the clearance gap between a case and a cover remove | eliminate the water which entered between the case and the cover irrespective of the attachment direction.

According to the present invention, a gas sensor is disposed inside an opening that protrudes from a case, has a side wall that is integral with the case, and is covered with a gas permeable membrane, and a cover that covers the opening is provided. In the vehicle-mounted gas detection device that leads the atmosphere from the gap to the gas sensor through the gas permeable membrane,
The cover includes a flat plate portion, and a double ring-shaped protrusion that protrudes from the periphery of the plate portion toward the side wall of the case and has a cut, and is arranged on the inner side so as to block the cut edge of the outer protrusion. Protrusions are arranged, the gap between the outer protrusion and the inner and outer protrusions and the inner protrusion are communicated to form a gas passage to the gas permeable membrane, and either the inner or outer protrusion is welded to the side wall. It is characterized by.
Preferably, hydrogen from the fuel cell is detected.

  In the present invention, since the gas permeable membrane and the gas passage are substantially at the same height, even if the gas detection device is mounted upside down, no dent in which water accumulates is generated. For this reason, the water accumulated between the gas permeable membrane and the cover can be drained. The dust in the atmosphere collides with the projections on the inside and is removed from the air flow, and does not reach the gas permeable membrane much. Next, since the cover is attached to the side wall by welding, the height of the cover with respect to the side wall is constant, and the size of the gas passage in the height direction is also constant. Furthermore, since welding is used, mass productivity is high when the cover is attached to the side wall. In the present invention, since the gas passage from the outside to the gas permeable membrane is short and the number of times the passage is bent during this period is small, the responsiveness to the atmosphere is high. For this reason, it is suitable for quickly detecting hydrogen leak from the fuel cell and maintaining safety.

  In the following, an optimum embodiment for carrying out the present invention will be shown.

  The gas detection apparatus 2 of an Example is shown in FIGS. In the figure, reference numeral 4 denotes a contact combustion type gas sensor, which comprises a detection piece 5 and a compensation piece 6. The gas sensor may be a metal oxide semiconductor gas sensor, a proton conductor gas sensor, or an electrochemical gas sensor. 7 is a substrate, 8 is a lower case, and 9 is an upper case, each of which is made of plastic. The upper case 9 includes an opening 10 protruding upward, and the detection piece 5 and the compensation piece 6 are accommodated in the opening 10, and 17 is an annular side wall of the opening 10. In order to prevent water from entering between the gaps between the cases 8 and 9, a packing 11 is provided, 12 is a cable for wiring, 13 is a bush, and 14 is a bolt for fixing the cases 8 and 9. A packing 15 is provided between the upper case 9 and the substrate 7 to prevent water and other foreign matters from entering the periphery of the gas sensor 4. 16 is a collar for positioning the upper and lower cases 8 and 9, and 18 is not necessarily provided by an O-ring. The O-ring 18 is used when the gas detection device 2 is airtightly set in an exhaust pipe of a fuel cell.

  Reference numeral 20 denotes a cover, and 22 is a gas permeable membrane such as PTFE, which is a membrane that allows gas to pass through without passing water. In the case of a fuel cell, a hydrogen selective permeable membrane may be used. The cover 20 includes a disk-shaped flat top plate portion 24 corresponding to the opening 10, and includes concentric double annular protrusions 25 and 26 around the periphery, each having a cut. When the center side is viewed from the outside of the cover 20, the ridges of the outer protrusions 25 are blocked by the inner protrusions 26, and the protrusions 25, 26 are arranged so that the cuts do not overlap in the radial direction. The gap between the outer protrusion 25, the gap between the inner and outer protrusions 25, 26, and the inner protrusion 26 are communicated to form a gas passage 28. The outer protrusion 25 is welded to the upper surface of the side wall 17 of the upper case 9 by the welding portion 30, but the inner protrusion 26 may be welded to the side wall 17 instead of the outer protrusion 25. There is almost no gap between the inner protrusion 26 and the gas permeable film 22.

  The operation of the embodiment will be described. The gas detection device 2 is disposed around the fuel tank, the exhaust pipe of the fuel cell, or the passenger compartment to detect hydrogen leakage in the fuel cell vehicle. Or it arrange | positions in an engine room etc., detects the contamination of outside air, and controls the introduction of outside air to a vehicle interior. The atmosphere reaches the upper portion of the gas permeable film 22 from the gas passage 28 between the protrusions 25 and 26, passes through the gas permeable film 22, and is guided to the space around the gas sensor 4. The ambient atmosphere collides with the protrusion 26 and reaches the upper part of the gas permeable membrane 22 as a swirling flow. Since the flow direction of the atmosphere is greatly changed only at one place when colliding with the protrusion 26, the response time can be shortened.

  Water droplets or the like are blocked by the protrusions 26 and hardly reach the upper part of the gas permeable film 22. Even if a water droplet or the like reaches the upper part of the gas permeable membrane 22, it is blown off by an air current or the like. The dust is removed by touching the projections 26 and the like, and even if a needle-like foreign substance or the like tries to enter from the gap between the projections 25, 25, it is difficult to reach the gas permeable film 22 by being blocked by the projections 26. For this reason, it is possible to prevent the gas permeable film 22 from being damaged by a sharp foreign substance or the like.

In assembling the gas detection device 2, the substrate 7 is set in the lower case 8, the upper case 9 and the lower case 8 are integrated with the bolt 14, the gas permeable membrane 22 and the cover 20 are arranged, and ultrasonic waves are used. The cover 20 is welded to the upper surface of the side wall 17. The gas permeable membrane 22 is bonded or welded before the cover 20 is welded, or is welded to the upper portion of the side wall 17 at the same time as the cover 20 is welded. Since the cover 20 is welded to the upper case 9, the height of the top plate portion 24 with respect to the upper case 9 is constant, and the height of the gas passage 28 is also constant. For this reason, the air permeability to the gas permeable membrane 22 can be kept constant. In welding, the productivity of mounting the cover 20 is high during mass production.

The figure which shows the decomposition | disassembly state of the gas detection apparatus of an Example The perspective view of the cover in an Example The perspective view which looked at the cover of Drawing 2 from the bottom side Sectional view of the gas detector of the embodiment 4 is an enlarged cross-sectional view of the main part of FIG.

Explanation of symbols

2 Gas detection device 4 Contact combustion type gas sensor 5 Detection piece 6 Compensation piece 7 Substrate 8 Lower case 9 Upper case 10 Opening 11, 15 Packing 12 Cable 13 Bush 14 Bolt 16 Collar 17 Side wall 18 O-ring 20 Cover 22 Gas permeable membrane 24 Top Plate part 25, 26 Protrusion 28 Gas passage 30 Welding part

Claims (2)

A gas sensor is disposed inside the opening that protrudes from the case, has a side wall that is integral with the case, and is covered with a gas permeable membrane, and a cover that covers the opening is provided, through the gap between the cover and the opening. In the gas detection device that guides the atmosphere to the gas sensor through the gas permeable membrane,
The cover includes a flat plate portion, and a double ring-shaped protrusion that protrudes from the periphery of the plate portion toward the side wall of the case and has a cut, and is arranged on the inner side so as to block the cut edge of the outer protrusion. Protrusions are arranged, the gap between the outer protrusion and the inner and outer protrusions and the inner protrusion are communicated to form a gas passage to the gas permeable membrane, and either the inner or outer protrusion is welded to the side wall. An on-vehicle gas detection device characterized by the above. The in-vehicle gas detection device according to claim 1, wherein hydrogen is detected from the fuel cell.

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