This application is based on and incorporates herein by reference Japanese Patent Application No. 2010-264978 filed on Nov. 29, 2010.
1. Field of the Invention
The present invention relates to a fuel vapor leakage inspection apparatus.
2. Description of Related Art
A fuel vapor leakage inspection apparatus that detects fuel vapor leaked from a fuel tank has been known. The fuel vapor leakage inspection apparatus includes a filter for collecting foreign objects such as dust and fine particles at the time of taking air from an outside of the fuel vapor leakage inspection apparatus. For example, Japanese Patent Publication JP 2006-051928A (corresponding to US 2006-0032482A1) teaches a fuel vapor leakage inspection apparatus, which includes the filter at the vicinity of a fuel supply port of a vehicle.
However, in this fuel vapor leakage inspection apparatus, at the time of inspecting the fuel vapor leakage, a pump is activated to reduce an inside pressure of the fuel tank. The pump radiates noise of air pulses, and transmitting noise is generated by vibration in the pump. Further, when a switching valve switches a canister passage communicating with a canister, parts of the switching valve are contacted with each other, thereby generating noise. When a certain period of time is passed after the engine is stopped, fuel vapor leakage starts being inspected. The noises are generated at the time of the operation of the fuel vapor inspection apparatus, and spread out of the vehicle.
The present invention addresses the above disadvantage. According to the present invention, there is provided a fuel vapor leakage inspection apparatus, which detects a leakage of a fuel vapor from a fuel tank through a canister that absorbs the fuel vapor. The fuel vapor leakage inspection apparatus includes a canister attachment portion, an air passage, a pumping device, a switching valve, a bypass passage, a throttle, a housing, and a filter. The canister attachment portion includes a canister passage communicating with an inside of the canister. The air passage has a first end connected to communicate with the canister passage and a second end connected with atmosphere. The pumping device increases and decreases an inside pressure of the canister, and one end of the pumping device is connected to communicate with the canister passage and the other end of the pumping device is connected to the air passage. The switching valve switches the canister passage to communicate with the air passage or the pumping device. One end of the bypass passage is connected to the canister passage and the other end of the bypass passage is connected to a passage defined between the pumping device and the switching valve. The throttle is provided in the bypass passage. The housing defines the air passage and the bypass passage, and accommodates the pumping device, the switching valve and the throttle. The filter is provided in the air passage and is accommodated in the housing.
The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:
Various embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, similar components are indicated by the same reference numerals and will not be redundantly described to simplify the description. In each of the following embodiments, if only a part of a structure is described, the remaining part of the structure is the same as that of the previously described embodiment(s). Any one or more components of any one of the following embodiments may be combined with the components of the other one of the following embodiments without departing a scope and spirit of the present invention.
As shown in
The fuel vapor leakage inspection apparatus 2 and the canister 12 are connected to each other through a canister channel 21. The fuel vapor leakage inspection apparatus 2 includes a pump 22, a switching valve 23, a pressure sensor 24, a bypass passage 26, a fuel vapor leakage sensing unit 20, and a filter 30. The pump 22 is used as a pumping device to pressurize and depressurize the gas in the fuel vapor leakage sensing unit 20. The fuel vapor leakage sensing unit 20 includes a reference orifice 27 and an air passage 28. The reference orifice 27 is used as a throttle of gas flowing through the bypass passage 26. The fuel vapor leakage sensing unit 20 and the filter 30 are accommodated in a housing 32. The fuel vapor leakage inspection apparatus 2 inspects a leakage of the fuel vapor from the fuel tank 10.
The pump 22 of the fuel vapor leakage sensing unit 20 is connected to the switching valve 23 through a pump passage 25, which is provided with the pressure sensor 24. The pump 22 reduces the pressure of an inside of the tank 10 via the canister channel 21 and the pump passage 25, which are communicated with each other by an operation of the switching valve 23. The operation of the switching valve 23 is discussed below. The pump passage 25 is connected to the bypass passage 26, which is provided with the reference orifice 27. The pump 22 is activated by a signal output from an electronic control unit (ECU) 3.
The switching valve 23 of the fuel vapor leakage sensing unit 20 is an electromagnetic valve. As shown in
The filter 30 is provided in the air passage 28. When the fuel vapor from the fuel tank 10 is absorbed by the canister 12, or when the pump 22 reduces the inside pressure of the fuel tank 10, the air flowing from the canister 12 is discharged to outside atmosphere through the filter 30. When the fuel vapor absorbed in the canister 12 is sent to the intake passage 16, or when a reference pressure is detected in a fuel vapor leakage inspection that is discussed below, air is introduced from the outside of the fuel vapor leakage inspection apparatus 2 through the filter 30. At this time, the filter 30 collects foreign objects that are included in the air flowing from the outside of the fuel vapor leakage inspection apparatus 2 to the canister 12. Arrows shown in
Next, a structure of the fuel vapor leakage inspection apparatus 2 will be described with reference to
The filter 30 is arranged within a housing interior space 321 at a side that is opposite from the canister attachment portion 211. The filter 30 is made of a non-woven fabric. As shown in
As shown in
Next, a function of the fuel vapor leakage inspection apparatus 2 according to the first embodiment will be described based on
After the measurement of the atmospheric pressure, the ECU 3 energizes the coil 231 of the switching valve 23. When the coil 231 is energized, the switching valve 23 moves toward the right side in
When a pressure increase caused by a fuel vapor generation in the inside of the fuel tank 10 is detected by the pressure sensor 24, the ECU 3 stops energizing the coil 231 of the switching valve 23. After the energizing the coil 231 is stopped, the pump passage 25 communicates with the canister channel 21 and the air passage 28 via the bypass passage 26.
Then, the pump 22 is energized, and the pressure of the inside of the pump passage 25 is reduced by the operation of the pump 22. Therefore, the air from the air passage 28 flows into the pump passage 25 through the bypass passage 26. The air flowing into the pump passage 25 is throttled by the orifice 27 of the bypass passage 26, thereby the inner pressure of the pump passage 25 is reduced. After the inner pressure of the pump passage 25 is reduced to a predetermined value that corresponds to an opening area of the orifice 27, the inner pressure of the pump passage 25 reaches a constant value. At this time, the pump 22 compresses air and discharging the compressed air, thereby noises are generated by the operation of the pump 22 and radiated to an outside of the pump 22. In addition, noises are generated by the vibration caused by the operation of the pump 22, and are transmitted to the inside of the housing 32. The radiated noises and the transmitted noises are absorbed by the filter 30, which is arranged at the vicinity of the fuel vapor leakage sensing unit 20. The noises transmitted to the inside of the housing 32 are reduced by the sound-absorbing function of the housing 32. The measured inner pressure of the pump passage 25 is recorded as the reference pressure. After the measurement of the reference pressure is completed, the operation of the pump 22 is stopped.
When the reference pressure is detected, the coil 231 of the switching valve 23 is energized again. Then, this interrupts the communication between the air passage 28 and the canister channel 21, and causes the canister channel 21 to communicate with the pump passage 25. Thereby, the fuel tank 10 communicates with the pump passage 25, and the inner pressure of the pump passage 25 becomes same as that of the fuel tank 10. At this time, the noises caused by the vibration of parts of the switching valve 23 are transmitted out of the switching valve 23. The transmitted noises are absorbed by the filter 30, which is arranged at vicinity of the fuel vapor leakage sensing unit 20. In addition, the noises transmitted to the inside of the housing 32 are reduced by the sound-absorbing function of the housing 32.
When the canister channel 21 and pump passage 25 are communicated with each other, the pump 25 is operated and the inner pressure in the fuel tank 10 is reduced. At this time, the pump 22 compresses the air and discharges the compressed air, thereby the noises generated by the operation of the pump 22 are radiated outside. In addition, the noises generated by the vibration are transmitted to the inside of the housing 32. The radiated noises and the transmitted noises are absorbed by the filter 30, which is arranged at the vicinity of the fuel vapor leakage sensing unit 20. In addition, the noises transmitted to the inside of the housing 32 are reduced by the sound-absorbing function of the housing 32.
When the inner pressure in the fuel passage 25, i.e., the inner pressure in the fuel tank 10, becomes lower than the pre-measured reference pressure by keeping the operation of the pump 22, it is determined that the leakage of the air, which includes the fuel vapor from the fuel tank 10, is less than tolerance. That is, when the inner pressure in the fuel tank 10 becomes lower than the reference pressure, it is considered that there is no intrusion of air from an outside of the fuel tank 10 to an inside thereof, or the amount of the flow of the intrusion air is smaller than that of the air which can pass through the reference orifice 27. In this case, it is judged that the air tightness of the inside of the fuel tank 10 is achieved.
On the other hand, if the inner pressure in the fuel tank 10 does not become lower than the pre-measured reference pressure by continuing to operate the pump 22, it is judged that the leakage of the air, which includes the fuel vapor from the fuel tank 10, is greater than the tolerance. That is, if the inner pressure in the fuel tank 10 does not become lower than the reference pressure, it is considered that there is the intrusion of the air from the outside of the fuel tank 10 to the inside thereof. In this case, it is determined that the air tightness of the inside of the fuel tank 10 is not achieved reliably.
After detecting the intrusion of the air from the outside of the fuel tank 10, i.e., the leakage of the air that includes the fuel vapor from the fuel tank 10, the energizing the pump 22 and the switching valve 23 are stopped. After the ECU 3 detects that the inner pressure in the pump passage 25 is recovered to the atmospheric pressure, it stops the operation of the pressure sensor 24, thereby the fuel vapor leakage inspection process is finished.
Next, effects of the fuel vapor leakage inspection apparatus 2 according to the first embodiment will be described.
(1) In the fuel vapor leakage inspection apparatus 2, the filter 30 is arranged at the vicinity of the fuel vapor leakage sensing unit 20. Therefore, at the time of detecting the fuel vapor leakage, the operating noises generated from the pump 22 and the switching valve 23 within the fuel vapor leakage sensing unit 20 is absorbed by the filter 30. Thereby, the operating noise generated within the fuel vapor leakage sensing unit 20 can be reduced.
(2) The fuel vapor leakage sensing unit 20 and the filter 30 are accommodated by the housing 32. At this time, the fuel vapor leakage inspection apparatus 2 is modularized by using the one housing 32, thereby high stiffness of the fuel vapor leakage inspection apparatus 2 is achieved. Therefore, the transmitted noises, which are caused by the vibration generated in the operation of the pump 22 and the switching valve 23, can be limited. Thereby, the transmitted noise generated within the fuel vapor leakage sensing unit 20 can be reduced by the high stiffness of the fuel vapor leakage inspection apparatus 2.
(3) The fuel vapor leakage sensing unit 20 and the filter 30 are accommodated by the housing 32. Therefore, the filter 30 and the fuel vapor leakage sensing unit 20 can be connected to each other without using parts for the connection. Thereby, the number of the parts, which are necessary for assembling the fuel vapor leakage inspection apparatus 2, can be reduced.
(4) By forming the housing interior space 321 as the air passage 28, the air flowing through the filter 30 directly flows into and out of the switching valve 23 of the fuel vapor leakage sensing unit 20. Therefore, an air-flow resistance, which is caused by the air flowing into and out of the fuel vapor leakage sensing unit 20, can be reduced.
(5) The filter 30 is arranged within the housing interior space 321 at the side that is opposite from the canister attachment portion 211. The connector 29, which receives a power supply from an outside of the fuel vapor leakage sensing unit 20, is arranged on an outer wall 382 of the housing 32, which is opposite from the canister attachment portion 211. At this time, the filter 30 is arranged around three sides, which are the upper side 33, the front side 36 and the back side 37 of the connector 29. Therefore, at the time of connecting an external terminal to the connector, which supply the power provided from the outside of the fuel vapor leakage sensing unit 20 thereto, the positioning of the connector can be easily adjusted on the housing 32, so that the connection of the external terminal and the connector can be easily performed.
(6) The air communicating passage 391, which causes the housing interior space 391 to communicate with the air around the outside of the housing 32, has the labyrinth structure. The operating noises generated within the fuel vapor leakage sensing unit 20 are discharged out of the housing 32 through the filter 30. At this time, the operating noises through the filter 30 are reduced due to repeated reflection with wall surface at the bent portion in the air communicating passage 391. Thereby, the operating noise generated within the fuel vapor leakage sensing unit 20 can be reduced.
A second embodiment of the present invention will be described with reference to
In the second embodiment of the present invention, as shown in
The filter 40 and the fuel vapor leakage sensing unit 20 are accommodated in the interior space 422a of the filter housing 422 and the interior space 423a of the sensing unit housing 423, respectively. Thus, the filter housing 422 and the sensing unit housing 423 can be divided. Therefore, at the time of maintenance of the fuel vapor leakage inspection apparatus 2, the filter housing 422 that accommodates the filter 40 can be detached from the fuel vapor leakage inspection apparatus 2. As a result, in addition to the effects (1) to (6) of the first embodiment, the maintenance of the fuel vapor leakage inspection apparatus 2 can be easily performed.
A third embodiment of the present invention will be described with reference to
As shown in
In the third embodiment, the filter 50, 60, 70, 80 is provided adjacent to the pump 22 and the switching valve 23 that generate the operating noises. The filter 50, 60, 70, 80 absorbs the generated operating noises. Thereby, the generated operating noises are effectively absorbed. As a result, in addition to the effects (1) to (6) of the first embodiment, the operating noise generated in the fuel vapor leakage inspection apparatus 2 can be effectively absorbed.
A fourth embodiment of the present invention will be described with reference to
In the fourth embodiment, as shown in
An air communicating portion 99 is arranged on an outer wall 982, which is opposite from the canister attachment portion 211 relative to the housing 92, and located at the lower front side (the lower right side in
The operating noise generated in the fuel vapor leakage sensing unit 20 is absorbed by the filter 90, which is located around the outer periphery of the fuel leakage sensing unit 20 as show in
(I) In above-described embodiments, the canister attachment portion 221 of the fuel vapor leakage sensing unit 20 can be installed on the lateral side of the outer wall of the canister 12. However, a location of the canister attachment portion 221, which corresponds to location of the canister 21, is not limited to this. The canister attachment portion 221 can be arranged in a location in the housing of the fuel vapor leakage sensing unit 20, which corresponding to an upper wall or a lower wall of the canister. In addition, the canister attachment portion 221 can be arranged in a pipe that connects to the canister 21.
(II) In the above-described embodiments, the detector for sensing the fuel vapor leakage of the inside of the fuel tank is the pressure sensor. However, the detector for sensing the fuel vapor leakage is not limited to this. The detector for sensing the fuel vapor leakage can be devices that detect an electric property of, for example, the current value of a motor driving a pump.
(III) In the first and second embodiment, the air communicating portion is arranged on the lower outer wall of the housing of the fuel vapor leakage inspection apparatus. However, the installation location of air communicating portion is not limited to this. The air communicating portion can be arranged in a location that is capable to be connected to the filter, for example, the outer wall of the front side or back side of the housing.
(IV) In the first and second embodiment, the filter arranged around the connector is provided at three sides, i.e., the upper side, the front side and the back side of the connector. However, the installation location of the filter is not limited to this. The filter can be arranged at, for example, the lower side and the both lateral side (the front side and the back side) of the connector or the lower side and the front side of the connector.
(V) In the third embodiment, the air communicating portion is provided on the outer wall that is opposite from the canister attachment portion of the housing of the fuel vapor leakage inspection apparatus. However, the installation location of the air communicating portion is not limited to this. The air communicating portion can be arranged on, for example, the upper side outer wall of the housing or the front side lateral wall of the housing.
(VI) In the third embodiment, the housing of the fuel vapor leakage inspection apparatus does not have the wall for dividing the interior space of the sensing unit housing. However, the wall can be arranged to divide the filter and the fuel vapor leakage sensing unit in the fuel vapor leakage inspection apparatus.
(VII) In the second and fourth embodiments, the air opening and the openings of the wall, which divides the interior space of the housing of the fuel vapor leakage inspection apparatus, are arranged such that the distance of the air flow passing through the inside of the filter can be maximized. However, the location of the air opening and the openings of the wall is not limited to this.
(VIII) In the above-described embodiments, the air opening of the air communicating portion opens toward the bottom of the fuel vapor leakage inspection apparatus. However, the opening direction of the air opening is not limited to this. The opening direction of the air opening can be face toward the upper side or the lateral side of the fuel vapor leakage inspection apparatus.
(IX) In the above-described embodiments, the air communicating portion has the labyrinth structure including the one bent portion. However, the number of the bent portion in the inside of the labyrinth structure is not limited to this. The multiple bent portions may be formed in the labyrinth structure.
Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.
Number | Date | Country | Kind |
---|---|---|---|
2010-264978 | Nov 2010 | JP | national |