JP2009068350A - Structure of atmospheric air introduction part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of an atmospheric air introduction part which can be used by both of fuel piping systems requiring and not requiring an internal pressure sensor. <P>SOLUTION: An atmospheric air introduction part (A) is equipped with a canister drain box 5 including an intake port 21a for feeding atmospheric air to a canister for temporarily capturing evaporated fuel through an atmospheric air introduction pipe P1 and an atmospheric pressure introduction box 6 including an atmospheric pressure introduction port 22a for introducing atmospheric pressure to the internal pressure sensor for detecting inside pressure in a fuel piping system through an atmospheric pressure introduction pipe P2. The canister drain box 5 and atmospheric pressure introduction box 6 are coupled to be one component and provided with flow paths 51, 61 with a labyrinth structure for preventing foreign matter from entering the atmospheric air introduction pipe P1 and atmospheric pressure introduction pipe P2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of an air introduction part that takes in air from a terminal part of a fuel piping system such as an air introduction pipe (drain pipe) connected to a canister, for example, in a vehicle.

  A canister mounted on an automobile is a device that temporarily stores evaporated fuel from a fuel tank in an adsorbent such as activated carbon and supplies the evaporated fuel to the engine side when the engine is started. When evaporative fuel is supplied from the canister to the engine side, air is drawn from the outside air through the air introduction pipe (drain pipe) provided on the canister side using the negative pressure of the started engine and adsorbed by the adsorbent. The evaporated fuel is desorbed by the intake air at that time and supplied to the engine side. The air inlet of the terminal of the air introduction pipe is disposed, for example, in a body frame under the floor of the vehicle with the opening end facing upward (see, for example, Patent Document 1).

  In addition, in fuel tank systems installed in automobiles of the US specification, etc., whether or not there are holes in the fuel tank or fuel piping system is determined by using the negative pressure of the intake pipe of the engine. Is provided with an internal pressure sensor (pressure sensor) for a failure detection device that diagnoses whether the negative pressure state is maintained or the atmospheric pressure state is maintained (see, for example, Patent Documents 1 and 2). .

  Conventionally, the intake port of the canister's air inlet pipe prevents foreign substances such as water and mud from entering, prevents the smell of gasoline from entering the cabin, and evaporates fuel discharged from the intake port. There is a restriction that it must be installed away from heat sources. In addition, there is a restriction that the atmospheric pressure inlet of the internal pressure sensor must be installed at a site where rainwater or the like can be prevented from entering.

  The atmospheric open end structure of the vehicle pipe line described in Patent Document 1 is such that rainwater or the like enters the atmosphere introduction pipe by installing a waterproof member having a lid covering the atmospheric pressure introduction port of the internal pressure sensor on the body frame. To prevent it.

  In the fuel vapor line system described in Patent Document 2, the atmosphere opening hole of the two-way valve is arranged to be opened in the cross member on the front side of the vehicle body via the atmospheric tube and the canister filter. Intrusion is prevented.

Japanese Patent No. 3497487 Japanese Patent Laid-Open No. 11-173229

However, since the internal pressure sensors described in Patent Documents 1 and 2 are used only for vehicles of the US specification, they may be unnecessary for vehicles in Japan.
In such a vehicle that does not require an internal pressure sensor, when the open-air end structure of a vehicle conduit described in Patent Document 1 is used, an internal pressure sensor, a bypass pipe, and a waterproof member are not required. The fuel piping system must be separate from the vehicle on which the sensor is mounted, and there is a problem that parts management and assembly work are troublesome.

As a means for solving this problem, it is conceivable to use a single member for the intake port of the air introduction pipe of the canister and the atmospheric pressure introduction port of the internal pressure sensor.
However, if the intake port of the canister's air introduction pipe and the atmospheric pressure introduction port of the internal pressure sensor are installed at the same position, when rainwater or the like enters the flow path, the intake port of the canister's air introduction pipe And the atmospheric pressure inlet of the internal pressure sensor may be blocked at the same time.
Therefore, it has been necessary to consider that the suction port of the canister and the atmospheric pressure introduction port of the internal pressure sensor are separated and installed at different locations.
When two pipes are added at one location, the value of the internal pressure of the fuel tank changes due to the negative pressure generated in the air introduction pipe connected to the canister when the canister is purged. There was a problem.

  Therefore, the present invention has been invented to solve the above-described problems, and can be used in a fuel piping system that requires an internal pressure sensor or a fuel piping system that does not require an internal pressure sensor. It is an object to provide a structure of a part.

  In order to solve the above-mentioned problem, the structure of the air introduction section according to claim 1 includes a canister drain box having an inlet for sending air through an air introduction pipe to a canister that temporarily captures evaporated fuel. An atmospheric pressure introduction box having an atmospheric pressure introduction box having an atmospheric pressure introduction port for introducing atmospheric pressure to an internal pressure sensor for detecting an internal pressure of the fuel piping system via an atmospheric pressure introduction pipe, The canister drain box and the atmospheric pressure introduction box are connected to form one part, and have a maze-type flow path that prevents foreign matter from entering the atmospheric introduction pipe and the atmospheric pressure introduction pipe. And

According to the first aspect of the present invention, the canister drain box and the atmospheric pressure introduction box are independently connected to each other in an adjacent state, and are composed of one part of a box structure, so that the atmosphere connected to the canister The air introduction part of the introduction pipe and the atmospheric pressure introduction part of the atmospheric pressure introduction pipe connected to the internal pressure sensor can be box-shaped. As a result, it is possible to expand the degree of freedom in selecting the installation location of the atmosphere introduction unit, shorten the atmosphere introduction pipe, reduce the number of installation steps, and simplify the installation work.
The atmospheric introduction section formed in this way uses an atmospheric pressure introduction box in the case of a fuel piping system that requires an internal pressure sensor, and uses an atmospheric pressure introduction box in the case of a fuel piping system that does not require an internal pressure sensor. The structure of the air introduction section that can be used with or without the internal pressure sensor can be provided.
Since the canister drain box and the atmospheric pressure introduction box have a maze-type flow path that prevents foreign matter from entering the respective air introduction pipes, the foreign matter is sucked into the air introduction pipes connected to the canister and the internal pressure sensor, respectively. Can be suppressed.
In addition, since the air introduction part of the air introduction pipe of the canister and the atmospheric pressure introduction part of the atmospheric pressure introduction pipe of the internal pressure sensor are separated from each other, they are generated in the air introduction pipe connected to the canister when the canister is purged. It becomes difficult to be affected by the negative pressure, and the change in the numerical value of the internal pressure of the fuel tank can be suppressed.

  The structure of the air introduction part according to claim 2 is the structure of the air introduction part according to claim 1, wherein the canister drain box includes a canister case part having the suction port, and the canister case part. A canister lid that engages the canister, and the atmospheric pressure introducing box connects the canister case or the sensor case integrally formed with the canister lid and the atmospheric pressure introducing pipe. And a sensor lid that engages with the sensor case.

  According to the invention of claim 2, the canister drain box and the atmospheric pressure introduction box are formed integrally with the canister case portion and the case portion, thereby reducing the number of parts and the number of installation steps. Cost can be reduced.

  The structure of the atmosphere introduction section according to claim 3 is the structure of the atmosphere introduction section according to claim 2, wherein the flow path of the maze structure of the canister drain box is connected to the inlet and the atmosphere introduction pipe. A labyrinth wall installed between the canister joint and the flow path of the labyrinth structure of the atmospheric pressure introduction box is installed between the atmospheric pressure introduction port and the sensor joint. It is characterized by including a foreign matter intrusion prevention wall.

According to the invention of claim 3, the flow path of the maze structure of the canister drain box is formed including a maze wall installed between the suction port and the canister joint to which the air introduction pipe is connected. For example, even if foreign matter such as rainwater or mud enters from the suction port, it is possible to prevent the foreign matter from entering the flow path side at the maze wall.
In addition, the flow path of the labyrinth structure of the atmospheric pressure introduction box is formed including the foreign matter intrusion prevention wall installed between the atmospheric pressure introduction port and the sensor joint, for example, from the atmospheric pressure introduction port. Even if foreign matter such as rainwater or mud enters, the foreign matter entry prevention wall can prevent foreign matter from entering the flow path.

  According to the structure of the air introduction part according to the present invention, the canister drain box and the atmospheric pressure introduction box are made of one part of the box structure, so that the air introduction part and the internal pressure sensor of the air introduction pipe connected to the canister can be used. The atmospheric pressure introduction part of the connected atmospheric introduction pipe can be box-shaped. As a result, the degree of freedom in selecting the installation location of the atmosphere introduction section can be expanded, the atmosphere introduction pipe can be shortened, the number of installation steps can be reduced, and the installation work can be simplified. In addition, the present invention can provide a structure of an air introduction portion that can be used even in a fuel piping system that requires an internal pressure sensor or a fuel piping system that does not require an internal pressure sensor.

With reference to FIGS. 1-5, an example of the structure of the air introduction part which concerns on embodiment of this invention is demonstrated.
FIG. 1 is a diagram showing a structure of an air introduction part according to an embodiment of the present invention, and is a schematic sectional view showing an installation state of a canister and an internal pressure sensor.
First, prior to describing the structure of the air introduction part A according to the embodiment of the present invention, the vehicle 1 in which the air introduction part A is installed will be described.

≪Vehicle configuration≫
As shown in FIG. 1, the vehicle 1 may be mounted with at least the fuel tank T and the canister C, and may or may not be mounted with the internal pressure sensor S. That is, the vehicle 1 only needs to be equipped with the fuel tank T and the canister C, and may be a passenger car, a truck, a bus, a work vehicle, or the like. In the vehicle 1, for example, a floor panel 12 is provided under a rear seat 11 in the passenger compartment, and a fuel tank T and a fuel tank T are disposed under the floor panel 12 behind the fuel tank T. A canister C, an internal pressure sensor S for detecting the pressure in the fuel piping system of the fuel tank T, and an air introduction part A of the fuel piping system of the fuel tank T are provided.

≪Fuel tank configuration≫
As shown in FIG. 1, the fuel tank T is a hollow container made of synthetic resin or metal for storing liquid automobile fuel such as gasoline, light oil, alcohol, etc. It is fixed by bolting a band (not shown) to the vehicle body. The fuel tank T includes a refueling float F to which an evaporative fuel pipe P3 is connected, a pump module (not shown) having a fuel pump (not shown), a fuel level gauge (not shown), and the like. A liquid fuel supply pipe (not shown), a vapor return float with a built-in float valve that closes when the tank is full, a fuel supply float with a built-in float valve, an inlet valve, a vapor return tube, etc. Yes.

The fuel piping system of the fuel tank T includes fuel piping such as a liquid fuel supply pipe (not shown), a fuel pipe, a purge pipe, a vent pipe, and a vapor return tube.
The liquid fuel supply pipe is a pipe for sending liquid fuel to the fuel tank T, and one end is connected to the fuel supply port and the other end is connected to the fuel tank T.
The fuel pipe is a pipe for sending liquid fuel to the engine. One end of the fuel pipe is connected to a pump module (not shown), and the other end is connected to the engine via an injector.
The purge pipe is a pipe for sending evaporated fuel to the engine. One end of the purge pipe is connected to the canister C, and the other end is connected to the engine via a purge adjusting solenoid valve (not shown) and an intake manifold.
The vent pipe is a pipe for sending evaporated fuel to the canister C. One end is connected to the vapor return float and the other end is connected to the canister C.
The vapor return tube is a pipe for circulating the evaporated fuel in the fuel tank T to the liquid fuel supply pipe, and one end is connected to the fuel supply float and the other end is connected to the liquid fuel supply pipe in the vicinity of the fuel supply port. ing.
The evaporative fuel pipe P3 is a so-called drain pipe, one end is connected to the oil supply float F, and the other end is connected to the atmospheric pressure introduction box 6 via the internal pressure sensor S and the atmospheric pressure introduction pipe P2.

≪Canister configuration≫
As shown in FIG. 1, the canister C captures the evaporated fuel in the fuel tank T and temporarily stores it, thereby preventing the evaporated fuel from being released into the atmosphere and storing it at the time of purging. The evaporative fuel is desorbed by the air sucked by the intake negative pressure of the engine and supplied to an intake manifold (not shown) of the engine (not shown). The canister C includes an adsorbent (not shown) in which the evaporated fuel in the upper space in the fuel tank T pushed by the injected fuel is temporarily adsorbed when refueling the fuel tank T. A drain filter (not shown) for removing dust contained in the atmosphere taken in at the time of purging, the atmosphere introduction pipe P1, and the vent pipe (not shown) for taking in the evaporated fuel connected to the fuel tank T. ) And.

≪Configuration of internal pressure sensor≫
The internal pressure sensor S is a pressure detection sensor of a failure detection device (not shown) that detects and alerts whether the fuel tank system and the fuel piping system have holes in the fuel tank system by detecting the pressure in the fuel piping system. is there. The internal pressure sensor S causes the fuel tank T and the entire fuel piping system to be in a negative pressure state by the intake negative pressure of the intake manifold, which is the intake system of the engine, according to a command from a control device provided in the failure detection device. Whether the state is kept or the atmospheric pressure state is detected by comparison with the atmospheric pressure taken from the atmospheric pressure introduction box 6 through the atmospheric pressure introduction pipe P2.

≪Configuration of air introduction part≫
As shown in FIG. 1, the air introduction part A is a part that takes in air in the air or discharges air that is temporarily captured and purified by the adsorbent of the canister C. The air introduction part A is installed at a high position under the floor in order to prevent foreign substances such as rainwater, muddy water, and mud from entering. The air introduction part A is composed of one part in which a canister drain box 5 and an atmospheric pressure introduction box 6 are connected.

FIG. 2 is an exploded perspective view showing the structure of the air introduction unit according to the embodiment of the present invention.
As shown in FIG. 2, the air introduction part A includes a case body 2 in which a canister case part 21 and a sensor case part 22 are integrally formed, and a canister lid body that is engaged with the upper side of the canister case part 21. 3, and a sensor lid 4 that is engaged with the upper side of the sensor case portion 22.

≪Configuration of canister drain box≫
As shown in FIG. 2, the canister drain box 5 is a box-shaped member for forming an inlet 21 a for sending air to the canister C. The canister case portion 21 and the canister case portion 21 include The canister cover 3 is engaged. The canister drain box 5 includes a suction port 21a for taking in atmospheric air, and a canister joint 21b to which the air introduction pipe P1 is connected. The canister drain box 5 and the atmospheric pressure introduction box 6 have flow paths 51 and 61 having a labyrinth structure for preventing foreign matters from entering the atmospheric introduction pipe P1 and the atmospheric pressure introduction pipe P2. .

≪Configuration of atmospheric pressure introduction box≫
The atmospheric pressure introduction box 6 is a box-shaped member for forming an atmospheric pressure introduction port 22a for sending atmospheric pressure to the internal pressure sensor S. The atmospheric pressure introduction box 6 includes a sensor case portion 22 formed integrally with the canister case portion 21, a sensor joint 41 for connecting the atmospheric pressure introduction pipe P2, and the sensor case portion 22 is engaged therewith. And a sensor lid 4. The atmospheric pressure introduction box 6 includes the atmospheric pressure introduction port 22a for taking in atmospheric air, and a sensor joint 41 to which the atmospheric pressure introduction pipe P2 is connected.

≪Case body configuration≫
As shown in FIG. 2, the case body 2 forms a lower case body of the boxed air introduction part A, and is fixed to the vehicle body by a bracket (not shown). The case body 2 mainly includes the canister case portion 21, the sensor case portion 22, and a connecting portion 23 provided between the canister case portion 21 and the sensor case portion 22 to connect the two. Are integrally formed of synthetic resin.

<Configuration of canister case>
The canister case portion 21 is a member that forms the lower case body of the canister drain box 5, and includes a suction port 21a, a flow channel 51, labyrinth walls 52 and 53, a suction chamber 54, a discharge chamber 55, A discharge port 21c, a canister joint 21b, and a locking portion 21d are provided.

The suction port 21a is an air intake for sending air to the canister C through the air introduction pipe P1, and is formed of a long hole formed in the bottom surface of the suction chamber 54 of the canister case portion 21.
The flow path 51 is a pipe for sending the air taken in from the suction port 21a to the discharge port 21c. The suction chamber 54, the discharge chamber 55, the inner wall of the canister case portion 21, the labyrinth walls 52 and 53, The inner wall of the canister lid 3 is formed.

  The flow path 51 of the canister drain box 5 is a flow path of air or the like formed so as to communicate with the canister joint 21b from the suction port 21a. The flow path 51 is formed in a maze structure so that the atmosphere meanders inside the canister case portion 21 and the canister lid 3 by matching. The channel 51 is formed including maze walls 52 and 53 installed between the suction port 21a and the canister joint 21b to which the atmosphere introduction pipe P1 is connected.

  The maze walls 52 and 53 mean that the air taken in from the suction port 21a is meandered and restricted to flow to the discharge port 21c, and foreign matter such as rainwater, mud and dust that has entered from the suction port 21a moves to the discharge chamber 55 side. It consists of a dam-like wall that suppresses this. The labyrinth walls 52 and 53 are provided perpendicularly to the central portion of the internal space formed by the canister case portion 21 and the canister lid 3, and the canister drain box 5 is connected to the suction chamber 54 having the suction port 21a. The canister case portion 21 is installed on the bottom surface on the upper side so as to be divided into a discharge chamber 55 having a discharge port 21c.

  FIG. 3 is a plan view showing the structure of the air introduction part according to the embodiment of the present invention. FIG. 4 is a perspective view showing the structure of the air introduction unit according to the embodiment of the present invention. 5 is a cross-sectional view in the direction of the arrow XX in FIG.

As shown in FIG. 2, the maze wall 52 is disposed so that, for example, the outer end surface and the upper end surface are in contact with the inner wall of the canister lid 3 and the ceiling surface 3 c (see FIG. 5). The discharge chamber 55 is provided in a partitioned state.
The labyrinth wall 52 is continuously formed in a state of being lowered one step to the side of the labyrinth wall 53 so that the upper end surface is separated from the stepped ceiling surface 3d of the canister lid 3 so that the flow path 51 is formed. Has been placed. The inside of the canister drain box 5 is in a state where the suction chamber 54 and the discharge chamber 55 are communicated with each other by the maze wall 53.

  2 and 5, the discharge port 21c is a cylindrical opening projecting upward from the bottom surface of the discharge chamber 55 of the canister case portion 21, and communicates with the canister joint 21b. ing. The discharge port 21c is formed at a position higher than the bottom surface of the discharge chamber 55 so that the foreign matter can be prevented from flowing into the canister joint 21b from the discharge port 21c. The discharge port 21c is disposed away from the ceiling surface 3c of the canister lid 3.

  As shown in FIGS. 2 and 5, the canister joint 21 b is a joint portion for connecting the air introduction pipe P <b> 1, one end communicates with the discharge port 21 c, and the other end extends from the lower surface of the canister case portion 21. It is formed to project in a letter shape (elbow shape).

  The locking portion 21 d is a claw-like portion for holding the canister lid 3 by engaging with an engaging portion 3 b formed on the outer peripheral portion of the canister lid 3, and the canister case portion 21. A plurality of outer peripheral portions are formed.

<Configuration of sensor case>
As shown in FIG. 2, the sensor case portion 22 is a member that forms the lower case body of the atmospheric pressure introduction box 6, and is integrally formed in a state adjacent to the canister case portion 21 via the connecting portion 23. Yes. The sensor case portion 22 includes an atmospheric pressure introduction port 22a and a locking portion 22b.
The atmospheric pressure inlet 22a is an atmospheric pressure inlet for sending atmospheric pressure to the internal pressure sensor S (see FIG. 1) via the atmospheric pressure introducing pipe P2 and loading it, and the end of the bottom surface of the sensor case 22 It consists of a hole drilled in.
The locking portion 22 b is a claw-like portion for holding the sensor lid body 4 by engaging with the engagement portion 4 b formed on the outer peripheral portion of the sensor lid body 4, and the sensor case portion 22. A plurality of outer peripheral portions are formed.

  As shown in FIGS. 2 and 3, the connecting portion 23 is a portion that connects the canister case portion 21 and the sensor case portion 22, and the canister case portion 21 and the sensor are disposed on the upper surface of the connecting portion 23. A reinforcing rib 23a for firmly supporting the case portion 22 is integrally formed.

≪Configuration of canister lid≫
As shown in FIG. 2, the canister lid 3 is a lid member that forms an upper case body of the canister drain box 5, and is lowered by one step from the engaging portion 3b, the ceiling surface 3c, and the ceiling surface 3c. A stepped ceiling surface 3d formed at the above position and a second suction port 3a drilled in the stepped ceiling surface 3d.
Similarly to the suction port 21a, the second suction port 3a is an opening for sucking air or discharging air from which evaporated fuel sent from the canister C (see FIG. 1) is sent through the air introduction pipe P1. Part. The second suction port 3 a is disposed at an upper portion of the discharge chamber 55 formed by matching the canister lid 3 with the canister case portion 21.

≪Configuration of sensor lid≫
As shown in FIG. 2, the sensor lid 4 is a lid member that forms the upper case body of the atmospheric pressure introduction box 6, and engages the engaging portion 4 b with the locking portion 22 b of the sensor case portion 22. Thus, the box body of the atmospheric pressure introduction box 6 is formed with the sensor case portion 22. The sensor lid 4 is integrally formed with a discharge port 4a, a sensor joint 41, an engagement portion 4b, a flow path 61, and foreign matter intrusion prevention walls 62 and 63.

The discharge port 4a is an opening for sending the air taken into the atmospheric pressure introduction box 6 from the atmospheric pressure introduction port 22a to the sensor joint 41, and is formed on the ceiling surface of the sensor lid 4 on the sensor joint 41 side. ing.
The sensor joint 41 is a joint portion to which the atmospheric pressure introduction pipe P <b> 2 is connected, and is formed of a cylindrical member projecting outward from a portion protruding from the lower surface of the sensor lid 4.
The engaging portion 4b is for fixing the sensor lid 4 to the sensor case portion 22 by engaging with the locking portion 22b.

  The flow path 61 of the labyrinth structure of the atmospheric pressure introduction box 6 is a flow path such as the atmosphere formed so as to communicate with the sensor joint 41 from the atmospheric pressure introduction port 22a. The flow path 61 is formed in a maze structure so that the atmosphere meanders inside the sensor case portion 22 and the sensor lid 4 by matching. The channel 61 is formed including foreign matter intrusion prevention walls 62 and 63 installed between the atmospheric pressure introduction port 22a and the sensor joint 41.

  The foreign matter intrusion prevention walls 62 and 63 mean that the air taken in from the atmospheric pressure introduction port 22a is meandered so as to flow to the discharge port 4a, and foreign matter such as rainwater, mud and dust that has entered from the atmospheric pressure introduction port 22a. It consists of a maze-like wall that suppresses movement toward the discharge port 4a. The foreign matter intrusion prevention walls 62 and 63 are formed in a state of hanging from the ceiling surface at a substantially central portion of the internal space formed by the sensor case portion 22 and the sensor lid body 4, and the lower end portion thereof is the sensor. It is installed in a state in contact with the inner bottom surface of the case portion 22. The foreign matter intrusion prevention wall 62 and the foreign matter intrusion prevention wall 63 are installed in the atmospheric pressure introduction box 6 in a state where the foreign matter intrusion prevention wall 62 is close to one side wall. The channel 61 is disposed at an appropriate interval so as to be close to the other side wall so that the flow path 61 is zigzag.

≪Action≫
Next, the effect | action of the structure of the air introduction part A which concerns on embodiment of this invention is demonstrated, referring FIGS. First, an operation in the case of the vehicle 1 of the US specification or the like in which the internal pressure sensor S is installed in the fuel piping system will be described together with an assembling procedure.

In this case, for example, as shown in FIG. 2, the canister cover 3 is assembled to the canister case portion 21, and the canister drain box 5 is assembled to the canister joint 21b as shown in FIGS. Connect the air introduction pipe P1.
2, the sensor lid 4 is assembled, the atmospheric pressure introduction box 6 is assembled as shown in FIGS. 3 and 4, and the atmospheric pressure introduction pipe P <b> 2 is attached to the sensor joint 41. Connecting.

  Next, as shown in FIG. 1, an internal pressure sensor S is interposed between the evaporated fuel pipe P connected to the pump module (not shown) and the atmospheric pressure introduction pipe P2 connected to the atmospheric pressure introduction box 6. Let The canister drain box 5 is connected to the air introduction pipe P1 connected to the canister C. In this way, the air introduction part A is arranged in the fuel piping system.

  Thus, in the fuel tank system of the vehicle 1 provided with the internal pressure sensor S, monitoring is performed to automatically detect whether the fuel tank T and the fuel piping system have holes or not while the engine is being driven by the internal pressure sensor S. ing. When detecting a hole, the negative pressure in the intake pipe of the engine is used to make the fuel tank T and the fuel piping system in a negative pressure state, and whether the negative pressure state is kept or the atmospheric pressure state is increased. The diagnosis is made by comparing with the atmospheric pressure introduced from the atmospheric pressure inlet 22a through the atmospheric pressure introducing box 6 and the atmospheric pressure introducing pipe P2.

  In that case, since the atmospheric pressure introduction box 6 is installed at a high position under the floor as shown in FIG. 1, it is possible to prevent foreign matters such as rainwater and mud from entering the atmospheric pressure introduction pipe P2. . If foreign matter enters the atmospheric pressure introduction box 6 from the atmospheric pressure introduction port 22a, as shown in FIG. 2, in the atmospheric pressure introduction box 6, the foreign matter is formed in a labyrinth so that the flow path 61 meanders. Since the intrusion prevention walls 62 and 63 are formed and the discharge port 4a is formed on the ceiling surface, foreign matter can be prevented from entering the atmospheric pressure introduction pipe P2 from the discharge port 4a and flowing into the internal pressure sensor S. be able to.

  In addition, the atmosphere introduction part A is formed of a single box structure in which the canister drain box 5 and the atmospheric pressure introduction box 6 are integrally formed and are connected to each other in an adjacent state. It is shaped. For this reason, since the air introduction part A can be installed at an appropriate place of the vehicle body by a bracket (not shown), the degree of freedom in selecting the installation place can be expanded, and the atmospheric pressure introduction pipe P2 can be shortened. Installation man-hours can be reduced and installation work can be simplified.

  In addition, since the suction port 21a of the atmospheric introduction pipe P1 of the canister C and the atmospheric pressure introduction port 22a of the atmospheric pressure introduction pipe P2 of the internal pressure sensor S are separate from each other, they are connected to the canister C when the canister C is purged. It is difficult to be affected by the negative pressure generated in the air introduction pipe P1, and the change in the numerical value of the internal pressure of the fuel tank can be suppressed.

Next, the case of the vehicle 1 without the internal pressure sensor S in the fuel piping system will be described.
In this case, since the evaporative fuel pipe P3 and the atmospheric pressure introduction pipe P2 shown in FIG. 1 are unnecessary as the internal pressure sensor S becomes unnecessary, the internal pressure sensor S, evaporative fuel pipe P3, and Remove the atmospheric pressure introduction pipe P2. Further, the sensor lid 4 shown in FIG.
That is, as shown in FIG. 2, in the air introduction part A, the case body 2 and the canister lid 3 are used for both the vehicle 1 that requires the internal pressure sensor S and the vehicle 1 that does not need it. Can be shared.
The sensor lid 4 may be attached to the sensor case 22 when the internal pressure sensor S is mounted on the vehicle 1, and it is not necessary to change the fuel piping system greatly. 1 can be easily handled.

  The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.

For example, the maze walls 52 and 53 may be located in either the canister case portion 21 or the canister lid 3.
Similarly, the foreign matter intrusion prevention walls 62 and 63 may be provided in either the sensor case 22 or the sensor lid 4.

It is a figure which shows the structure of the air | atmosphere introduction part which concerns on embodiment of this invention, and is a schematic sectional drawing which shows the installation state of a canister and an internal pressure sensor. It is a disassembled perspective view which shows the structure of the air introduction part which concerns on embodiment of this invention. It is a top view which shows the structure of the air introduction part which concerns on embodiment of this invention. It is a perspective view which shows the structure of the air | atmosphere introduction part which concerns on embodiment of this invention. FIG. 4 is a cross-sectional view in the direction of arrow XX in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Case main body 3 Canister lid 4 Sensor lid 5 Canister drain box 6 Atmospheric pressure introduction box 21 Canister case portion 21a Intake port 21b Canister joint 22 Sensor case portion 22a Atmospheric pressure introduction port 41 Sensor joint 51, 61 Flow path 52, 53 Maze wall 62, 63 Foreign matter intrusion prevention wall A Atmospheric introduction part C Canister P1 Atmospheric introduction pipe P2 Atmospheric pressure introduction pipe S Internal pressure sensor

Claims (3)

A canister drain box having an inlet for sending the atmosphere through an atmosphere introduction pipe to a canister that temporarily captures evaporative fuel;
An atmospheric pressure introduction box having an atmospheric pressure introduction box having an atmospheric pressure introduction port for introducing atmospheric pressure to an internal pressure sensor for detecting an internal pressure of the fuel piping system via an atmospheric pressure introduction pipe,
The canister drain box and the atmospheric pressure introduction box are connected to form one part, and have a maze-structure channel that prevents foreign matter from entering the atmospheric introduction pipe and the atmospheric pressure introduction pipe. Characteristic structure of air introduction part. The canister drain box includes a canister case portion having the suction port, and a canister lid body with which the canister case portion is engaged,
The atmospheric pressure introduction box has a sensor case portion integrally formed with the canister case portion or the canister lid, a sensor joint for connecting the atmospheric pressure introduction pipe, and the sensor case portion The structure of the air introduction part according to claim 1, further comprising a sensor lid body to be engaged. The flow path of the maze structure of the canister drain box is formed including a maze wall installed between the suction port and a canister joint to which the atmosphere introduction pipe is connected,
3. The flow path of the labyrinth structure of the atmospheric pressure introduction box is formed to include a foreign matter intrusion prevention wall installed between the atmospheric pressure introduction port and the sensor joint. Structure of the air introduction part described in 1.

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