JP2013245653A - Fuel vapor leakage detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel vapor leakage detecting device capable of miniaturizing a physical constitution.SOLUTION: An inside of a housing 40 is partitioned into a housing inner space 401 for storing a pump 22 or the like by a partition wall 41, and an adsorbing chamber 402 for storing an adsorbing material 50. The partition wall 41 is formed with a through-hole 411 for communicating the housing inner space 401 and the adsorbing chamber 402, and an atmospheric passage 281 is communicated with the adsorbing chamber 402. When performing fuel vapor leakage detecting processing, when adsorbing capacity of a canister adsorbing material 121 is reduced, fuel vapor unadsorbable by the canister adsorbing material 121 is discharged to the housing inner space 401 by passing through the pump 22. The fuel vapor of the housing inner space 401 is adsorbed by the adsorbing material 50 when flowing toward the atmospheric passage 281. Thus, discharge to an external part of the fuel vapor is prevented by the absorbing material 50 stored in the housing 40, and the physical constitution of the fuel vapor leakage detecting device 5 can be miniaturized.

Description

  The present invention relates to a fuel vapor leak detection device that detects a fuel vapor leak in a fuel tank.

  2. Description of the Related Art Conventionally, a fuel vapor leak detection device that detects a fuel vapor leak in a fuel tank and a canister that adsorbs fuel vapor in the fuel tank is known. The fuel vapor leak detection device includes a pump that depressurizes the fuel tank and the canister, a switching valve that switches the fuel tank and the canister to the pump or to the atmosphere. Patent Document 1 describes a fuel vapor leak detection device that adsorbs fuel vapor passing through a pump to an adsorbent included in an air cleaner element in an intake pipe when the adsorption capability of a canister is decreasing.

JP 2007-198394 A

  However, the fuel vapor leak detection device described in Patent Document 1 must include a connection pipe that connects the fuel vapor leak detection device and the intake pipe in order to guide the fuel vapor passing through the pump to the air cleaner element. Further, since the air cleaner element needs to be provided with an adsorbent capable of adsorbing fuel vapor, the size of the fuel vapor leak detection device is increased.

  An object of the present invention is to provide a fuel vapor leak detection device that can be downsized.

  A depressurizing means housed in a housing and depressurizing the inside of the fuel tank and the canister; and an adsorbent that adsorbs fuel vapor passing through the depressurizing means when the depressurizing means depressurizes the inside of the fuel tank and the canister. A fuel vapor leak detection device for detecting a fuel vapor leak in a canister that adsorbs fuel vapor in a fuel tank, wherein the adsorbent is provided between the decompression means and the atmosphere.

  When the adsorption capacity of the adsorbent is reduced in the fuel vapor leak detection procedure, if the pressure in the fuel tank is reduced by the pressure reducing means, the fuel vapor in the fuel tank is not adsorbed by the canister but is discharged into the housing through the pump. Is done. The fuel vapor in the housing is adsorbed by an adsorbent provided between the decompression means and the atmosphere before being released to the atmosphere through the atmospheric passage. Thereby, it is possible to prevent the fuel vapor from being released to the atmosphere during the fuel vapor leakage detection process. Further, since the connection pipe that connects the fuel vapor leak detection device and the intake pipe and the air cleaner element having the adsorbent are not required as compared with the conventional fuel vapor leak detection device, the size can be reduced.

It is a conceptual diagram of the evaporative fuel processing apparatus using the fuel vapor leak detection apparatus by 1st Embodiment of this invention. It is sectional drawing of the fuel vapor leak detection apparatus by 1st Embodiment of this invention. It is the III-III sectional view taken on the line of FIG. It is a conceptual diagram of the evaporative fuel processing apparatus using the fuel vapor leak detection apparatus by 2nd Embodiment of this invention. It is a conceptual diagram of the evaporative fuel processing apparatus using the fuel vapor leak detection apparatus by 3rd Embodiment of this invention.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 3 show a fuel vapor leak detection apparatus according to a first embodiment of the present invention.
1 includes a fuel tank 10, a canister 12, a fuel vapor leak detection device 5, an atmospheric filter 23, an ECU 8, and the like. In the evaporated fuel processing apparatus 1, the canister 12 collects evaporated fuel generated in the fuel tank 10. The canister 12 purges the recovered fuel vapor into the intake passage 161 formed by the intake pipe 16 connected to the engine 9.

  The fuel tank 10 stores fuel supplied to the engine 9. The fuel tank 10 is connected to the canister 12 by a first purge pipe 11. The first purge pipe 11 forms a first purge passage 111 that communicates between the fuel tank 10 and the canister 12.

  The canister 12 includes a canister adsorbent 121 that collects the evaporated fuel generated in the fuel tank 10. The canister 12 is connected to the intake pipe 16 by a second purge pipe 13 that forms a second purge passage 131. A purge valve 14 is installed in the second purge pipe 13. The evaporated fuel generated in the fuel tank 10 passes through the first purge passage 111 and is collected by being adsorbed by the canister adsorbent 121. The purge valve 14 is an electromagnetic valve, and the amount of evaporated fuel purged from the canister 12 to the downstream side of the throttle valve 18 in the intake passage 161 is adjusted by controlling the opening of the purge valve 14.

  The fuel vapor leak detection device 5 includes a canister connection portion 21, a pump 22, a switching valve 30, a pressure sensor 24 as a "pressure detecting means", a pressure detection pipe 25, a switching valve bypass pipe 26, a housing 40, a reference orifice 27, an adsorption It is composed of a material 50, an atmospheric passage tube 28 and the like. The fuel vapor leak detection device 5 detects fuel vapor leaks in the fuel tank 10 and the canister 12 by reducing the pressure in the fuel tank 10 and the canister 12 with a pump 22. Further, when the fuel vapor leak detection device 5 purges the fuel vapor collected in the canister 12 into the intake pipe 16, the air introduced into the canister 12 passes therethrough. The detailed structure of the fuel vapor leak detection device 5 will be described later.

  The atmospheric filter 23 is connected to one end on the atmospheric side of the atmospheric passage tube 28 as an “atmospheric passage forming member” that forms the atmospheric passage 281. When fuel vapor is adsorbed by the canister 12, when the pump 22 depressurizes the fuel tank 10, or when fuel is supplied into the fuel tank 10, the fuel tank 10 or the canister 12 is supplied from the atmospheric filter 23. Air is discharged into the atmosphere. On the other hand, when the fuel vapor adsorbed on the canister 12 is supplied to the intake pipe 16 or when the reference pressure is detected in the fuel vapor leak detection process described later, the air passes from the atmosphere to the fuel vapor leak detection device 5 through the atmospheric filter 23. Is introduced. At this time, the atmospheric filter 23 collects foreign matters contained in the introduced air. In addition, the arrow in FIG. 1 has shown the flow of air.

  The ECU 8 is composed of a CPU as arithmetic means and a microcomputer having RAM and ROM as storage means. The ECU 8 is electrically connected to the pressure sensor 24, the pump 22, and the coil 31. A signal corresponding to the pressure in the pressure detection passage 251 detected by the pressure sensor 24 is input to the ECU 8. The ECU 8 outputs a signal for controlling the driving of the pump 22. The ECU 8 controls energization to the coil 31.

Next, the structure of the fuel vapor leak detection device 5 will be described mainly with reference to FIGS.
As shown in FIG. 2, the fuel vapor leak detection device 5 according to the first embodiment includes a pump 22, a switching valve 30, a pressure sensor 24, an adsorbent 50, and the like as “pressure reducing means” housed in a housing 40 and modularized. It is a thing. The fuel vapor leak detection device 5 is installed by fitting a canister connection portion 21 as a “communication port forming member” provided on the connection wall 47 of the housing 40 with a mounting hole formed on the side wall of the canister 12. The In FIG. 2, the upward direction is “top direction” and the downward direction is “ground direction”.

  The housing 40 has a substantially rectangular parallelepiped shape and is made of resin. As shown in FIGS. 2 and 3, a partition wall 41 that partitions the interior of the housing 40 is formed inside the housing 40. The interior of the housing 40 is communicated with a canister connection port 211 as a “communication port” by a partition wall 41, a housing inner space 401 that houses the pump 22, the switching valve 30, and the like, an adsorption chamber 402 that houses the adsorbent 50, It is divided into. The partition wall 41 is formed with a through hole 411 that allows the housing inner space 401 and the suction chamber 402 to communicate with each other.

  In the housing inner space 401, the pump 22 is installed on the top wall 43 side of the top side of the housing 40. The pressure sensor 24 is provided on the opposite side of the canister connection portion 21 with respect to the switching valve 30. The connector 29 that receives power supplied from the outside is installed on the opposite connection wall 46 opposite to the connection wall 47 where the canister connection portion 21 is formed.

  The pump 22 is connected to the switching valve 30 via a pressure detection pipe 25 as a “pressure detection passage forming member” in which the pressure sensor 24 is installed (see FIG. 1). The pump 22 is a pump that drives the rotor 224 by a motor 222 that is a brushless DC motor. The pump 22 depressurizes the inside of the fuel tank 10 through the pressure detection pipe 25, the switching valve 30, the canister connection portion 21, the canister 12, and the first purge pipe 11. At this time, the pressure sensor 24 as “pressure detection means” installed in the pressure detection pipe 25 detects the pressure in the fuel tank 10 by detecting the pressure in the pressure detection passage 251.

  The pump 22 has a pump discharge port 221 through which air introduced into the fuel tank 10 or air discharged from the fuel tank 10 passes. The pump discharge port 221 opens toward the side wall 44 on the side opposite to the side wall 45 on the side where the pressure sensor 24 is installed. When the pump 22 depressurizes the fuel tank 10, the rotor 224 rotates to suck the air in the fuel tank 10. The sucked air is discharged from the pump discharge port 221 to the housing inner space 401 as indicated by an arrow F in FIG. The air in the housing inner space 401 is discharged to the outside of the housing 40 through the adsorbent 50 provided along the lower wall 42 on the ground side of the housing 40 and the atmospheric passage 281 connected to the adsorbent 50. The arrow F indicates the flow of air discharged from the housing inner space 401 to the outside of the housing 40 through the adsorption chamber 402 and the atmospheric passage 281.

  The switching valve 30 is an electromagnetic valve, and includes a valve body 32, a valve shaft member 33, an electromagnetic drive unit 34, an on-off valve 35, and a reference valve 36. The on-off valve 35 includes a first valve seat 351 formed on the valve body 32 and a valve 352 attached to the valve shaft member 33. The reference valve 36 includes a second valve seat 361 formed in the housing 40 and a valve cap 362 attached to the end of the valve shaft member 33.

  The valve body 32 has a bottomed cylindrical shape, and accommodates a valve shaft member 33, an electromagnetic drive unit 34, an on-off valve 35, and a reference valve 36 therein. A switching valve discharge port 323 is formed in the valve body 32. The switching valve discharge port 323 communicates the second connection space 322 formed inside the valve body 32 and the outside of the valve body 32, that is, the housing inner space 401.

  The valve shaft member 33 is driven by the electromagnetic drive unit 34. The valve shaft member 33 has a valve 352 attached in the middle of the axial direction and a valve cap 362 attached to an end portion in the axial direction. The electromagnetic drive unit 34 includes an elastic member 39 that presses the valve shaft member 33 toward the second valve seat 361. The electromagnetic drive unit 34 includes a coil 31 that is electrically connected to the ECU 8 via the connector 29.

  When the coil 31 is not energized, no magnetic attractive force is generated between the fixed core 37 and the movable core 38 of the electromagnetic drive unit 34. Therefore, the valve shaft member 33 that is integrally connected to the movable core 38 moves to the left in FIG. 2 by the pressing force of the elastic member 39. As a result, the valve cap 362 is seated on the second valve seat 361. On the other hand, the valve 352 is separated from the first valve seat 351. Thereby, the canister connection port 211 and the housing inner space 401 communicate with each other via the first connection space 321, the second connection space 322, and the switching valve discharge port 323. Therefore, when energization of the coil 31 is stopped, the flow of intake air between the canister connection port 211 and the pressure detection passage 251 is interrupted, and the air between the canister connection port 211 and the switching valve bypass passage 261 is blocked. Flow is only allowed through the reference orifice 27. A reference orifice 27 as a “throttle section” provided in the switching valve bypass pipe 26 as a “bypass passage forming member” has a hole size that is an upper limit value of an allowable amount of air leakage including evaporated fuel from the fuel tank 10. It corresponds to.

  When the coil 31 is energized by a command from the ECU 8, a magnetic attractive force is generated between the fixed core 37 and the movable core 38. The valve shaft member 33 connected integrally with the movable core 38 moves to the right in FIG. 2 against the pressing force of the elastic member 39. The valve cap 362 is separated from the second valve seat 361 and the valve 352 is seated on the first valve seat 351. As a result, the canister connection port 211 communicates with the pressure detection passage 251 through the first connection space 321. On the other hand, since the valve 352 is seated on the first valve seat 351, the first connection space 321 and the second connection space 322 are blocked. Therefore, when the coil 31 is energized, the flow of air between the canister connection port 211 and the pressure detection passage 251 is allowed, and the canister connection port 211 and the housing inner space 401 passing through the second connection space 322 are allowed to flow. The air flow between them is interrupted. It should be noted that the canister connection port 211 and the pressure detection passage 251 always communicate with each other via the reference orifice 27 regardless of whether the coil 31 is energized.

  The adsorbent 50 is provided in the adsorption chamber 402 along the lower wall 42 of the housing 40. The adsorbent 50 is made of a material capable of adsorbing fuel vapor, for example, granular activated carbon. An atmospheric passage pipe 28 that forms an atmospheric passage 281 that communicates with the adsorption chamber 402 is connected to the lower wall 42 of the housing 40 that forms the adsorption chamber 402.

  Next, the operation of the fuel vapor leak detection device 5 according to the first embodiment of the present invention will be described. The fuel vapor leak detection device 5 executes a fuel vapor leak detection process for detecting a fuel vapor leak in the fuel tank 10 by reducing the pressure in the fuel tank 10 with the pump 22.

  When a predetermined period elapses after the operation of the engine 9 mounted on the vehicle is stopped, the ECU 8 is activated by a soak timer (not shown) and starts fuel vapor leak detection processing of the fuel tank 10. In detection, atmospheric pressure is detected in order to correct an error due to the altitude at which the vehicle is parked. When the coil 31 is not energized, the atmospheric passage 281 communicates with the canister connection port 211 via the housing inner space 401, the switching valve discharge port 323, the second connection space 322, and the first connection space 321. The canister connection port 211 communicates with the pressure detection passage 251 through the switching valve bypass passage 261. That is, the pressure detection passage 251 communicates with the atmosphere. Therefore, the atmospheric pressure is detected by the pressure sensor 24 installed in the pressure detection tube 25. When the detection of the atmospheric pressure is completed, the ECU 8 calculates the altitude of the place where the vehicle is parked from the detected pressure.

  Next, energization of the pump 22 is started and the pressure detection passage 251 is depressurized. Thereby, the air flowing in from the atmospheric passage 281 passes through the housing inner space 401, the switching valve discharge port 323, the second connection space 322, the first connection space 321, the canister connection port 211, and the switching valve bypass passage 261. It flows into the pressure detection passage 251. Since the flow of air flowing into the pressure detection passage 251 is throttled by the reference orifice 27 of the switching valve bypass passage 261, the pressure in the pressure detection passage 251 decreases. The pressure in the pressure detection passage 251 becomes constant after dropping to a predetermined pressure corresponding to the opening area of the reference orifice 27. The detected pressure in the pressure detection passage 251 is recorded as a reference pressure. When the detection of the reference pressure is completed, the energization to the pump 22 is stopped.

  When the reference pressure is detected, the coil 31 of the switching valve 30 is energized again. Thereby, the canister connection port 211 and the atmospheric passage 281 are blocked, and the canister connection port 211 and the pressure detection passage 251 communicate with each other. Thus, the fuel tank 10 communicates with the pressure detection passage 251 and the pressure in the pressure detection passage 251 becomes the same as that of the fuel tank 10.

  When the canister connection port 211 and the pressure detection passage 251 communicate with each other, the pump 22 operates and the inside of the fuel tank 10 is depressurized. At this time, when a large amount of fuel vapor is adsorbed on the canister adsorbent 121, fuel vapor that cannot be adsorbed by the canister adsorbent 121 flows to the fuel vapor leak detection device 5. The fuel vapor flowing through the fuel vapor leak detection device 5 is discharged from the pump 22 into the housing inner space 401 as shown in FIGS. The fuel vapor discharged into the housing inner space 401 flows into the atmospheric passage 281 due to the discharge pressure of the pump 22. At this time, the fuel vapor is adsorbed by the adsorbent 50.

  When the pressure of the pressure detection passage 251, that is, the internal pressure of the fuel tank 10 is reduced by the continuation of the operation of the pump 22, the leakage of air including fuel vapor from the fuel tank 10 is less than the allowable amount. It is judged that there is. That is, when the pressure inside the fuel tank 10 falls below the reference pressure, there is no air intrusion from the outside to the inside of the fuel tank 10, or the invading air is less than or equal to the flow rate of the reference orifice 27. Therefore, it is determined that the air tightness of the fuel tank 10 is sufficiently ensured.

  On the other hand, when the pressure inside the fuel tank 10 does not decrease to the reference pressure, it is determined that the air leak including the fuel vapor from the fuel tank 10 exceeds the allowable amount. That is, when the pressure inside the fuel tank 10 does not drop to the reference pressure, it is considered that air has entered the fuel tank 10 from the outside as the pressure inside the fuel tank 10 is reduced. Therefore, it is determined that the airtightness of the fuel tank 10 is not sufficiently ensured.

  When the detection of the air leak including the fuel vapor is completed, the energization to the pump 22 and the switching valve 30 is stopped. After detecting that the pressure in the pressure detection passage 251 has recovered to atmospheric pressure, the ECU 8 stops the operation of the pressure sensor 24 and ends the fuel vapor leak detection process.

  In the fuel vapor leak detection device 5 of the first embodiment, when detecting the fuel vapor leak in the fuel tank 10, the adsorbent 50 collects the fuel vapor in the fuel tank 10 sucked by the pump 22. In particular, when the excessive adsorption capacity of the canister adsorbent 121 is low, such as when a large amount of fuel vapor is adsorbed on the canister adsorbent 121 or when the adsorption capacity of the canister adsorbent 121 is deteriorated, the inside of the fuel tank 10 Since the fuel vapor is not completely recovered by the canister adsorbent 121, it flows to the fuel vapor leak detection device 5. Therefore, the fuel vapor leak detection device 5 is provided with an adsorbent 50 for recovering the fuel vapor passing through the pump 22 in the housing 40 and adsorbs the fuel vapor so as not to leak into the atmosphere. In the fuel vapor leak detection device 5 of the first embodiment, the adsorbent 50 is housed in the housing 40 together with the pump 22 and the pressure sensor 24, so that the fuel vapor is collected at a different location from the fuel vapor leak detection device 5. There is no need to provide an adsorbent. Thereby, a physique can be made small compared with the conventional fuel vapor leak detection apparatus which provides an adsorbent in an inlet pipe.

  Moreover, since the adsorbent 50 is accommodated in the housing 40, the number of parts can be reduced. In addition, the number of parts can be reduced by reducing the number of parts, and the manufacturing cost can be reduced.

  Further, by providing the adsorbent 50 between the switching valve 30 and the atmospheric passage 281, it is possible to reduce pressure pulsation generated by switching the communication destination of the canister connection port 211 in the switching valve 30.

(Second Embodiment)
Next, a fuel vapor leak detection apparatus according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in the position where the adsorbent is provided. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

  The fuel vapor leak detection device 6 according to the second embodiment includes a canister connection portion 21, a pump 22, a switching valve 30, a pressure sensor 24, a pressure detection pipe 25, a switching valve bypass pipe 26, a housing 40, a reference orifice 27, and an atmospheric passage pipe. 28, an atmospheric filter 63 is provided. The atmospheric filter 63 has an adsorbent 60.

  The adsorbent 60 of the fuel vapor leak detection device 6 adsorbs the fuel vapor that the canister adsorbent 121 could not adsorb when the pump 22 depressurizes the fuel tank 10 and the canister 12. Thereby, in the fuel vapor leak detection process, the fuel vapor passing through the pump 22 can be recovered without being released to the atmosphere. Therefore, the same effect as that of the first embodiment is obtained.

(Third embodiment)
Next, a fuel vapor leak detection apparatus according to a third embodiment of the present invention will be described with reference to FIG. The third embodiment differs from the first embodiment in the position where the adsorbent is provided. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

  In the fuel vapor leak detection device 7 according to the third embodiment, the adsorbent 70 is provided in the atmospheric passage pipe 28 connected to the housing 40 and the atmospheric filter 23. The adsorbent 70 adsorbs the fuel vapor that the canister adsorbent 121 could not adsorb when the pump 22 depressurizes the fuel tank 10 and the canister 12.

  In the fuel vapor leak detection device 7, an adsorbent 70 that adsorbs fuel vapor is provided as a part of the air passage tube 28. Thereby, in the fuel vapor leak detection process, the fuel vapor passing through the pump 22 can be recovered without being released to the atmosphere. Therefore, the same effect as that of the first embodiment can be obtained in the fuel vapor leak detection process of the fuel tank 10.

(Other embodiments)
(A) In the first embodiment described above, the adsorbent is provided along the lower wall of the housing. However, the position where the adsorbent is provided with respect to the housing is not limited to this. You may provide along the upper wall on the opposite side to the side wall of a housing, and a lower wall. Further, it may be provided along two or more walls.

  (B) In the above-described embodiment, the adsorbent is granular activated carbon. However, the material and shape of the adsorbent are not limited to this. Any material capable of adsorbing fuel vapor may be used, and the shape may be other than granular.

  As mentioned above, this invention is not limited to such embodiment, It can implement with a various form in the range which does not deviate from the summary.

5, 6, 7 ... Fuel vapor leak detection device,
10: Fuel tank,
12 ・ ・ ・ Canister,
22 ... Pump (pressure reduction means),
23, 63 ... Air filter,
28 ... Atmospheric passage tube (atmospheric passage forming member),
281 ... atmospheric passage,
30 ... switching valve,
40 ・ ・ ・ Housing,
401... Space inside housing
50, 60, 70 ... adsorbent.

Claims (3)

A fuel vapor leak detection device (5, 6, 7) for detecting a fuel vapor leak in a fuel tank (10) and a canister (12) that adsorbs fuel vapor in the fuel tank,
A housing (40);
A communication port forming member (21) provided on the outer wall of the housing and forming a communication port (211) communicating with the canister;
An atmospheric passage forming member (28) for forming an atmospheric passage (281) communicating the interior of the housing with the atmosphere;
A pressure detection passage forming member (25) forming a pressure detection passage (251) capable of communicating with the communication port;
A switching valve (30) capable of selectively switching the communication port to communicate with the pressure detection passage or to the atmospheric passage;
Pressure reducing means (22) provided in the housing, and for reducing pressure in the fuel tank and the canister when the switching valve communicates the communication port and the pressure detection passage;
A bypass passage forming member (26) that bypasses the switching valve and forms a switching valve bypass passage (261) that connects the communication port and the pressure detection passage;
A throttle part (27) provided in the bypass passage forming member;
Pressure detection means (24) for detecting the pressure of the pressure detection passage and outputting a signal corresponding to the detected pressure of the pressure detection passage;
An adsorbent (50, 60, 70) that is provided between the decompression means and the atmosphere, and adsorbs fuel vapor that passes through the decompression means when the decompression means decompresses the fuel tank and the canister;
A fuel vapor leak detection device comprising: The adsorbent is accommodated in an adsorption chamber (402) formed inside the housing,
2. The fuel vapor leak detection device according to claim 1, wherein the adsorption chamber (402) communicates a housing inner space (401) accommodating the decompression means and the atmospheric passage. An atmospheric filter (63) provided at an end of the atmospheric passage opposite to the housing and removing foreign substances in the air flowing into the fuel tank or the canister;
The fuel vapor leak detection device according to claim 1, wherein the adsorbent is provided in the atmospheric filter.

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