Fuel supply device

A fuel supply device includes an inlet pipe, a first end of the inlet pipe configured to be connected to an oil supply port and a second end of the inlet pipe configured to be connected to a fuel tank and an air flow path, an upstream side end of the air flow path configured to be open to the outside and a downstream side end of the air flow path configured to be connected to the fuel tank. The air flow path includes a negative pressure valve configured to move a valve body to open a valve port when the pressure in the fuel tank becomes a negative pressure and an air filter disposed upstream of the negative pressure valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2017-222809 filed on Nov. 20, 2017, which is incorporated herein by reference in its entirety including the specification, drawings and abstract.

BACKGROUND

1. Technical Field

The present disclosure relates to a fuel supply device.

2. Description of Related Art

Japanese Unexamined Patent Application Publication No. 05-301530 (JP 05-301530 A) discloses a technique in which, as means for causing air in the atmosphere to flow into a fuel tank when the pressure in the fuel tank of an automobile becomes lower than the atmospheric pressure and becomes a negative pressure, an air flow path through which the atmosphere and the inside of an inlet pipe communicate with each other is formed in a fuel cap that opens and closes an oil supply port of the inlet pipe and the air flow path is provided with a negative pressure valve. The air flow path in the fuel cap is formed into a curved path as means for restraining dust in the atmosphere from entering a tiller pipe when air in the atmosphere flows into the inlet pipe with the negative pressure valve opened and a dust collecting recess portion for collecting dust is provided upstream of the negative pressure valve in the air flow path.

SUMMARY

In the case of the fuel cap, dust collected in the dust collecting recess portion may be whirled up by an air stream passing through the air flow path and the dust may adhere to a valve seat or a valve body of the negative pressure valve since the dust collecting recess portion faces the air flow path. In a case where the dust adheres to the negative pressure valve, the negative pressure valve is not fully closed because the dust is caught between the valve seat and the valve body when the negative pressure valve is closed.

The disclosure provides a fuel supply device with which it is possible to achieve an improvement in reliability of a negative pressure valve.

An aspect of the disclosure relates to a fuel supply device including an inlet pipe and an air flow path. A first end of the inlet pipe is configured to be connected to an oil supply port and a second end of the inlet pipe is configured to be connected to a fuel tank. An upstream side end of the air flow path is configured to be open to the outside and a downstream side end of the air flow path is configured to be connected to the fuel tank. The air flow path includes a negative pressure valve and an air filter. The negative pressure valve is configured to move a valve body to open a valve port when the pressure in the fuel tank becomes a negative pressure. The air filter is disposed upstream of the negative pressure valve.

In the fuel supply device according to the aspect of the disclosure, the negative pressure valve and the air filter may be integrated with each other and may constitute a valve module that is detachable from the air flow path. In this case, the workability at the time of maintenance of the air filter or the negative pressure valve is favorable.

The fuel supply device according to the aspect of the disclosure may further include a breather pipe configured to connect the inlet pipe and the fuel tank to each other, and a canister pipe, a first end of the canister pipe configured to be open to the outside and a second end of the canister pipe configured to be connected to a canister. The negative pressure valve may be configured to connect the breather pipe and the canister pipe to each other. In this case, the breather pipe and the canister pipe are integrated with each other via the negative pressure valve. Therefore, vibration of the breather pipe and the canister pipe during traveling can be further suppressed.

In the fuel supply device according to the aspect of the disclosure, the negative pressure valve may be provided on an outer circumference of the inlet pipe or an outer circumference of the breather pipe, and the air filter may be disposed to cover the outer circumference of the inlet pipe and the negative pressure valve or to cover the outer circumference of the breather pipe and the negative pressure valve. In this case, it is possible to achieve space-saving in comparison with a case where the negative pressure valve and the air filter are provided to protrude in a radial direction from the outer circumference of the inlet pipe or the outer circumference of the breather pipe.

The fuel supply device according to the aspect of the disclosure may further include a valve housing and a filter unit. The negative pressure valve may include a primary chamber and a secondary chamber. The secondary chamber may be formed in the valve housing and the valve body may be accommodated in the secondary chamber. The primary chamber may be formed in the filter unit and the inside of the primary chamber may be partitioned into an introducing chamber communicating with the atmosphere and a clean chamber facing the valve port by the air filter. The filter unit may be configured to be detachable from the valve housing. In this case, the workability at the time of maintenance of the air filter is favorable.

In the fuel supply device according to the aspect of the disclosure, the negative pressure valve may include a cylindrical portion that accommodates the valve body and the cylindrical portion may integrally protrude in a radial direction from a circumferential surface of the inlet pipe. In this case, the number of components can be reduced in comparison with a case where the cylindrical portion and the inlet pipe are provided separately from each other.

In the fuel supply device according to die aspect of the disclosure, the negative pressure valve may include a cylindrical portion that accommodates the valve body and the cylindrical portion may integrally protrude in a radial direction from a circumferential surface of the breather pipe.

According to the aspect of the disclosure, air in the atmosphere flows into the fuel tank after sequentially passing through the air filter and the negative pressure, valve when the negative pressure valve is opened. However, the dust in the atmosphere does not reach the negative pressure valve since the dust cannot pass through the air filter. Therefore, it is possible to prevent a malfunction of the negative pressure valve that occurs when the dust in the atmosphere is caught.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, Example 1 which is a specific example of the aspect of the disclosure will be described with reference toFIGS. 1 and 2. Regarding the vertical direction, directions inFIGS. 1 and 2will be referred to as upward and downward directions in the following description. Regarding the horizontal direction, directions inFIGS. 1 and 2will be referred to as rightward and leftward directions.

A fuel supply device10in Example 1 is provided with a fuel tank11, an inlet pipe12for supplying fuel to the fuel tank11, a fuel cap14that opens and closes a fuel or oil supply port13of the inlet pipe12, and a valve module18. A lower end portion of the inlet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11. In a state where the fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed.

A cylindrical attachment portion15for attaching the valve module18to the inlet pipe12is formed to protrude on an outer circumference of an upstream side end portion (position near oil supply port13) of the inlet pipe12. The internal space of the cylindrical attachment portion15communicates with the inside of the inlet pipe12(fuel inflow path). A plurality of elastic locking pieces16disposed to surround the cylindrical attachment portion15is formed to protrude on an outer circumference of the inlet pipe12.

An area from the cylindrical attachment portion15of the inlet pipe12to the fuel tank11constitutes an air flow path17for causing air in the atmosphere to flow into the fuel tank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure).

The valve module18is obtained by accommodating a normally closed negative pressure valve23and an air filter30in a housing19and integrating the negative pressure valve23and the air filter30with each other. The housing19is obtained by assembling and combining a plurality of members. A cylindrical fitting portion20is formed on a side surface of the housing19. A seal ring21is mounted onto an inner circumference of the cylindrical fitting portion20. A stepped locking portion22is formed on an outer circumference of the cylindrical fitting portion20. The valve module18is attached to the outer circumference of an upper end portion of the inlet pipe12when the cylindrical fitting portion20is externally fitted onto the cylindrical attachment portion15and the elastic locking pieces16are engaged with the locking portion22.

In the housing19, a primary chamber24and a secondary chamber25that constitute the negative pressure valve23are provided. The primary chamber24and the secondary chamber25constitute the air flow path17along with the inlet pipe12. An introducing port26through which the primary chamber24and the atmosphere communicate with each other is formed in a lower end portion of the primary chamber24(upstream side end of air flow path17). The secondary chamber25is disposed to be horizontally adjacent to an upper end portion of the primary chamber24and communicates with the internal space of the cylindrical fitting portion20.

A partition wall that separates the secondary chamber25and the primary chamber24from each other is formed with a valve port27that penetrates the partition wall. In the secondary chamber25, a valve body28for opening and closing the valve port27and a spring member29that urges the valve body28in a valve closing direction are accommodated. The secondary chamber25communicates with the inlet pipe12(air flow path17) via the cylindrical fitting portion20and the cylindrical attachment portion15.

In a usual state, the valve body28air-tightly closes the valve port27due to an urging force of the spring member29so that the negative pressure valve23is maintained in a closed state in which the primary chamber24and the secondary chamber25are air-tightly isolated from each other. When the pressure in the secondary chamber25(in fuel tank11) becomes lower than the pressure in the primary chamber24, the valve body28moves against the urging force of the spring member29in a direction such that the valve port27is opened. Therefore, the primary chamber24and the secondary chamber25communicate with each other and the negative pressure valve23enters an opened state. When the negative pressure valve23enters the opened state, air in the atmosphere is introduced into the primary chamber24via the introducing port26and the air flows into the fuel tank11after sequentially passing through the valve port27, the secondary chamber25, the cylindrical fitting portion20, the cylindrical attachment portion15, and the air flow path17(inlet pipe12).

Since dust floats in the atmosphere (air), when the negative pressure valve23is opened, the dust flows into the primary chamber24along with the air. In a case where the dust adheres to the valve port27or the valve body28of the negative pressure valve23, the negative pressure valve23may not be fully closed because the dust is caught between an opening edge of the valve port27and the valve body28when the negative pressure valve23is closed.

As a countermeasure for the above-described problem, the primary chamber24in the fuel supply device10according to Example 1 is vertically partitioned by the bellows-shaped air filter30. The air filter30allows the atmospheric air (air) to pass through the air filter30while the air filter30inhibits the dust in the atmosphere from passing through the air filter30. A space below the air filter30in the primary chamber24(space that is upstream of air filter30in air flow path17) is an introducing chamber31that is open to the atmosphere at the introducing port26. A space above the air filter30in the primary chamber24(space that is downstream of air filter30in air flow path17) is a clean chamber32that can communicate with the secondary chamber25via the valve port27.

The dust in the air is captured by the air filter30during a process in which the pressure in the fuel tank11becomes a negative pressure, the negative pressure valve23is opened, and air flowing into the introducing chamber31(primary chamber24) via the introducing port26passes through the air filter30. Therefore, clean air mixed with substantially no dust flows into the clean chamber32. Accordingly; there is no possibility that the dust is caught between the opening edge of the valve port27and the valve body28when the negative pressure valve23is closed.

The fuel supply device10according to Example 1 includes the inlet pipe12configured such that a first end of the inlet pipe12is connected to the oil supply port13and a second end of the inlet pipe12is connected to the fuel tank11and the air flow path17configured such that an upstream side end of the air flow path17is open to the outside and a downstream side end of the air flow path17is connected to the fuel tank11. The air flow path17includes the negative pressure valve23configured such that the valve body is moved and the valve port is opened when the pressure in the fuel tank11becomes a negative pressure and the air filter30disposed upstream of the valve port27(secondary chamber25) of the negative pressure valve23.

In the case of the above-described configuration, air in the atmosphere flows into the fuel tank11after sequentially passing through the air filter30and the negative pressure valve23when the negative pressure valve23is opened. However, the dust in the atmosphere does not reach the negative pressure valve23since the dust cannot pass through the air filter30. Therefore, it is possible to prevent a malfunction of the negative pressure valve23that occurs when the dust in the atmosphere is caught.

The negative pressure valve23and the air filter30are integrated with each other via the housing19and constitute the valve module IS. The valve module18is detachable from the inlet pipe12that constitutes the air flow path17. Therefore, at the time of maintenance of the air filter30or the negative pressure valve23, it is possible to detach the valve module18from the inlet pipe12by elastically deforming the elastic locking pieces16and releasing the elastic locking pieces16from the locking portion22. Since the housing19is obtained by assembling and combining a plurality of members, the air filter30or the negative pressure valve23can be detached when the housing19is disassembled. Therefore, the workability at the time of maintenance is favorable.

Example 2 which is a specific example of the aspect of the disclosure will be described with reference toFIG. 3. Regarding the vertical direction, directions inFIG. 3will be referred to as upward and downward directions in the following description. Regarding the horizontal direction, directions inFIG. 3will be referred to as rightward and leftward directions.

A fuel supply device33in Example 2 is obtained by making the configuration of an air flow path35different from that in Example 1. Since the other components are the same as those in Example 1, the same components are given the same reference numerals and description of configurations, operations, and effects thereof will be omitted.

The fuel supply device33in Example 2 is provided with the fuel tank11, the inlet pipe12for supplying fuel to the fuel tank11, the fuel cap14that opens and closes the oil supply port13of the inlet pipe12, a breather pipe34through which air in the fuel tank11is discharged to the outside while oil is being supplied, and the valve module18. A lower end portion of the inlet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11.

In a state where the fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed. An upper end portion of the breather pipe34is connected to a portion of the inlet pipe12that is positioned slightly below the oil supply port13(positioned downstream of oil supply port13in oil supply path) such that the upper end portion communicates with the inlet pipe12. The lower end portion of the breather pipe34is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11.

The cylindrical attachment portion15(not shown inFIG. 3) for attaching the valve module18to the breather pipe34is formed to protrude on an outer circumference of the breather pipe34. The internal space of the cylindrical attachment portion15communicates with the inside of the breather pipe34. The elastic locking pieces16disposed to surround the cylindrical attachment portion15is formed to protrude on the outer circumference of the breather pipe34.

An area from the cylindrical attachment portion15of the breather pipe34to the fuel tank11constitutes the air flow path35for causing air in the atmosphere to flow into the fuel tank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure). The configuration and the operation effect of the valve module18are the same as those in Example 1. In the following description, the valve module18will be given the reference numeral in the document.

The dust in the air is captured by the air filter30during a process in which the pressure in the fuel tank11becomes a negative pressure, the negative pressure valve23is opened, and air flowing into the introducing chamber31(primary chamber24) via the introducing port26passes through the air filter30. Therefore, clean air mixed with substantially no dust flows into the clean chamber32. Accordingly, there is no possibility that the dust is caught between the opening edge of the valve port27and die valve body28when the negative pressure valve23is closed.

Example 3 which is a specific example of the aspect of the disclosure will be described with reference toFIGS. 4 and 5. Regarding the vertical direction, directions inFIGS. 4 and 5will be referred to as upward and downward directions in the following description. Regarding the horizontal direction, directions inFIGS. 4 and 5will be referred to as rightward and leftward directions.

A fuel supply device36in Example 3 is provided with the fuel tank11, the inlet pipe12for supplying fuel to the fuel tank11, the fuel cap14that opens and closes the oil supply port13of the inlet pipe12, a breather pipe37through which air in the fuel tank11is discharged to the outside while oil is being supplied, a canister pipe38, a filter unit41, and a valve unit48. In a state where die fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed.

A lower end portion of the inlet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11. An upper end portion of the breather pipe37is connected to a portion of the inlet pipe12that is positioned slightly below the oil supply port13(positioned downstream of oil supply port13in oil supply path) such that the upper end portion communicates with the inlet pipe12. The lower end portion of the breather pipe37is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11.

A canister40is provided in the middle of the canister pipe38and a lower end portion of the canister pipe38is connected to the fuel tank11. Fuel vapor that is generated in the fuel tank11while oil is being supplied is adsorbed by activated carbon in the canister40so that clean air is discharged to the atmosphere through the canister pipe38and the filter unit41. When the fuel vapor adsorbed in the canister40is released through a negative-pressure purging process of an engine (not shown), the pressure in the canister40becomes a negative pressure so that the outside air is taken into the canister40through the filter unit41and the canister pipe38.

An upper end portion of the canister pipe38is positioned in the vicinity of the upper end portion of the inlet pipe12. The upper end portion of the canister pipe38is formed as a communication port39and the filter unit41is attached to the communication port39. The filter unit41is configured with a filter housing42and an air filter43that is accommodated in the filter housing42. The filter housing42is attached to the outer circumference of the upper end portion of the inlet pipe12(in vicinity of oil supply port13).

The inside of the filter housing42is vertically partitioned by the air filter43. The air filter43allows air to pass through the air filter43while the air filter43inhibits the dust in the air from passing through the air filter43. A space above the air filter43in the filter housing42is an introducing chamber45that communicates with the atmosphere via an introducing port44. A space below the air filter43in the filter housing42is a clean chamber46that communicates with the communication port39of the canister pipe38.

A portion of the breather pipe37and a portion of the canister pipe38are routed to be substantially parallel to each other and to be close to each other and an intermediate portion of each of the breather pipe37and the canister pipe38is divided into parts at a space where the portion of the breather pipe37and the portion of the canister pipe38are routed to be substantially parallel to each other. The valve unit48is attached to divided portions37S of the breather pipe37and divided portions38S of the canister pipe38. The breather pipe37and the canister pipe38are connected to each other such that the divided portions37S of the breather pipe37and the divided portions38S of the canister pipe38can communicate with each other via the valve unit48.

The internal space of the filter unit41, an area from the communication port39of the canister pipe38to a connection portion between the canister pipe38and the valve unit48, the internal space of the valve unit48, and an area from a communication portion between the breather pipe37and the valve unit48to a communication portion (connection portion) between the breather pipe37and the fuel tank11constitute an air flow path47. The air flow path47is an inflow path for causing air in the atmosphere to flow into the fuel tank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure).

The valve unit48is obtained by accommodating a normally closed negative pressure valve53in a valve housing49. The valve housing49is obtained by assembling and combining a plurality of members. The valve housing49is configured with a breather side cylindrical connection portion50to be connected to the breather pipe37, a canister side cylindrical connection portion51to be connected to the canister pipe38, and a cylindrical connection portion52through which the breather side cylindrical connection portion50and the canister side cylindrical connection portion51communicate with each other.

Upper and lower end portions of the breather side cylindrical connection portion50that protrude upward and downward from the cylindrical connection portion52are air-tightly fixed in a state of being internally fitted into the divided portions37S of the breather pipe37. Therefore, the divided portions37S of the breather pipe37are connected to each other in a row via the breather side cylindrical connection portion50. The breather side cylindrical connection portion50constitutes the breather pipe37and the air flow path47.

Upper and lower end portions of the canister side cylindrical connection portion51that protrude upward and downward from the cylindrical connection portion52are air-tightly fixed in a state of being internally fitted into the divided portions38S of the canister pipe38. Therefore, the divided portions38S of the canister pipe38are connected to each other in a row via the canister side cylindrical connection portion51. The canister side cylindrical connection portion51constitutes the canister pipe38and the air flow path47. The inside of the canister side cylindrical connection portion51functions as a primary chamber54of the negative pressure valve53. A valve port55that penetrates the canister side cylindrical connection portion51in a direction from an inner circumference to an outer circumference of the canister side cylindrical connection portion51is formed in an area in the canister side cylindrical connection portion51that is aligned with the cylindrical connection portion52.

The cylindrical connection portion52is integrally formed with the breather side cylindrical connection portion50and protrudes toward the canister side cylindrical connection portion51from an outer circumference of the breather side cylindrical connection portion50. A protruding end portion of the cylindrical connection portion52is air-tightly fixed to the outer circumference of the canister side cylindrical connection portion51. The internal space of the cylindrical connection portion52communicates with the breather side cylindrical connection portion50and functions as a secondary chamber56of the negative pressure valve53. The secondary chamber56constitutes the air flow path47. In the secondary chamber56(in cylindrical connection portion52), a valve body57for opening and closing the valve port55and a spring member58that urges the valve body57in a valve closing direction are accommodated.

In a usual state, the valve body57air-tightly closes the valve port55due to an urging force of the spring member58so that the negative pressure valve53is maintained in a closed slate in which the primary chamber54and the secondary chamber56are air-tightly isolated from each other. When the pressure in the secondary chamber56(in fuel tank11) becomes lower than the pressure in the primary chamber54, the valve body57moves against the urging force of the spring member58in a direction such that the valve port55is opened. Therefore, the primary chamber54and the secondary chamber56communicate with each other and the negative pressure valve53enters an opened state. When the negative pressure valve53enters the opened state, air in the atmosphere is introduced into the introducing chamber45of the filter housing42via the introducing port44and passes through the air filter43. Then, the air flows into the fuel tank11after sequentially passing through the clean chamber46, the canister pipe38, the primary chamber54, the valve port55, the secondary chamber56, and the breather pipe37.

Although the dust Hooting in the atmosphere (air) also flows into the filter housing42when the negative pressure valve53is opened, the dust in air is captured by the air filter43during a process of passing through the air filter43. Therefore, clean air mixed with substantially no dust flows into the clean chamber46. Accordingly, there is no possibility that the dust is caught between an opening edge of the valve port55and the valve body57when the negative pressure valve53is closed.

The fuel supply device36according to Example 3 includes the inlet pipe12configured such that the first end of the inlet pipe12is connected to an oil supply port13and the second end of the inlet pipe12is connected to the fuel tank11and the air flow path47configured such that an upstream side end of the air flow path47is open to the outside and a downstream side end of the air flow path47is connected to the fuel tank11. The air flow path47includes the negative pressure valve53configured such that the valve body is moved and the valve port is opened when the pressure in the fuel tank31becomes a negative pressure and the air filter43disposed upstream of the valve port55(secondary chamber56) of the negative pressure valve53.

In the case of the above-described configuration, air in the atmosphere flows into the fuel tank11alter sequentially passing through the air filter43and the negative pressure valve53when the negative pressure valve53is opened. However, the dust in the atmosphere does not reach the negative pressure valve53since the dust cannot pass through the air filter43. Therefore, it is possible to prevent a malfunction of the negative pressure valve53that occurs when the dust in the atmosphere is caught.

The fuel supply device36according to Example 3 includes the breather pipe37that is configured to connect a portion of the inlet pipe12that is downstream of the oil supply port13and is in the vicinity of the oil supply port13and the fuel tank11to each other and the canister pipe38that is disposed to be parallel to the breather pipe37and is configured such that a first end of the canister pipe38is open to the outside and a second end of the canister pipe38is connected to the canister40. In addition, the valve unit48provided with the negative pressure valve53is provided such that the valve unit48connects the breather pipe37and the canister pipe38to each other. In the case of the above-described configuration, the breather pipe37and the canister pipe38are integrated with each other via the negative pressure valve53(valve unit48). Therefore, vibration of the breather pipe37and the canister pipe38during (raveling is further suppressed.

Hereinafter, Example 4 which is a specific example of the aspect of the disclosure will be described with reference toFIGS. 6 and 7. Regarding the vertical direction, directions inFIG. 6will be referred to as upward and downward directions in the following description.

A fuel supply device59in Example 4 is provided with the fuel tank11, the inlet pipe12for supplying fuel to the fuel tank11, the fuel cap14that opens and closes the oil supply port13of the inlet pipe12, a breather pipe60through which air in the fuel tank11is discharged to the outside while oil is being supplied, a canister pipe61, and a valve module64. In a state where the fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed.

A lower end portion of the inlet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11. An upper end portion of the breather pipe60is connected to a portion of the inlet pipe12that is positioned slightly below the oil supply port13(positioned downstream of oil supply port13in oil supply path) such that the upper end portion communicates with the inlet pipe12. The lower end portion of the breather pipe60is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11.

The valve module64is attached to the breather pipe60. The valve module64and an area from the valve module64of the breather pipe60to the fuel tank11constitute an air flow path63for causing air in the atmosphere to flow into the fuel tank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure). An upper end portion of the canister pipe61is connected to a lower surface of the valve module64.

The valve module64is configured to include a housing65, a normally closed negative pressure valve70, an air filter78, and an attachment member81. The negative pressure valve70and the air filter78are integrated with the housing65. The housing65is configured to include a primary side casing66in which a primary chamber67of the negative pressure valve70is formed and a secondary side casing68in which a secondary chamber69of the negative pressure valve70is formed. The shape of the primary side casing66as seen in a plan view is an approximate semi-arc shape. The radius of curvature of an inner circumference of the approximate semi-arc shape is equal to the outer diameter of the breather pipe60. The secondary side casing68protrudes from an inner circumference of the primary side casing66.

The housing65is fixed to the breather pipe60by the plate-shaped attachment member81that has an approximate semi-arc shape as seen in a plan view. In a state where the housing65is fixed to the breather pipe60, the primary side casing66and the attachment member81are in close-contact with an outer circumference of the breather pipe60and the breather pipe60is interposed between the primary side casing66and the attachment member81in a radial direction. In addition, opposite end portions of the primary side casing66and the attachment member81in a circumferential direction are fixed to each other by a fastening member (not shown) such as a bolt and a nut. The secondary side casing68is air-tightly fitted into an attachment hole82that is formed in the breather pipe60such that the attachment hole82penetrates the breather pipe60and the secondary side casing68faces the inside of the breather pipe60.

The primary chamber67and the secondary chamber69constitute the air flow path63along with the breather pipe60. An introducing port71that penetrates a first circumferential end portion of an outer circumferential wall portion of the primary side casing66such that the primary chamber67communicates with the atmosphere is formed in the primary side casing66. A communication port72and a water drain port74are formed in a second circumferential end portion of a lower wall portion of the primary side casing66such that the communication port72and the water drain port74penetrate the second circumferential end portion. A retaining wall portion73that protrudes toward the primary chamber67side (upper side) is formed over the entire circumference of an opening edge of the communication port72.

An upper end portion of the canister pipe61is air-tightly connected to the communication port72. A canister62is provided in the middle of the canister pipe61. A lower end portion of the canister pipe61is connected to the fuel tank11. Fuel vapor that is generated in the fuel tank11while oil is being supplied is adsorbed by activated carbon in the canister62so that clean air is discharged to the atmosphere through the canister pipe61and the introducing port71of the valve module64. When the fuel vapor adsorbed in the canister62is released through a negative-pressure purging process of an engine (not shown), the pressure in the canister62becomes a negative pressure so that the outside air is taken into the canister62via the introducing port71after passing through the valve module64and the canister pipe61.

A valve port75for causing the primary chamber67and the secondary chamber69to communicate with each other is formed in an inner circumferential wall portion of the primary side casing66. In the secondary chamber69, a valve body76for opening and closing the valve port75and a spring member77that urges the valve body76in a valve closing direction are accommodated. The secondary chamber69communicates with the breather pipe60. In a usual state, the valve body76air-tightly closes the valve port75due to an urging force of the spring member77so that the negative pressure valve70is maintained in a closed state in which the primary chamber67and the secondary chamber69are air-tightly isolated from each other.

When the pressure in the secondary chamber69(in fuel tank11) becomes lower than the pressure in the primary chamber67, the valve body76moves against the urging force of the spring member77in a direction such that the valve port75is opened. Therefore, the primary chamber67and the secondary chamber69communicate with each other and the negative pressure valve70enters an opened state. When the negative pressure valve70enters the opened state, air in the atmosphere is introduced into the primary chamber67via the introducing port71and the air flows into the fuel tank11after sequentially passing through the valve port75, the secondary chamber69, and the breather pipe60.

Since dust floats in the atmosphere (air), when the negative pressure valve70is opened, the dust flows into the primary chamber67along with the air. In a case where the dust adheres to the valve port75or the valve body76of the negative pressure valve70, the negative pressure valve70may not be fully closed because the dust is caught between an opening edge of the valve port75and the valve body76when the negative pressure valve70is closed.

As a countermeasure for the above-described problem, the primary chamber67in the fuel supply device59according to Example 4 is partitioned into an inner circumferential space and an outer circumferential space by the bellows-shaped air filter78that is disposed in the circumferential direction. The air filter78allows the atmospheric air (air) to pass through the air filter78while the air filler78inhibits the dust in the atmosphere from passing through the air filter78. A space in the primary chamber67that is positioned radially outward of the air filter78(space that is upstream of air filter78in air flow path63) is an introducing chamber79that is open to the atmosphere at the introducing port71. A spare in the primary chamber67that is positioned radially inward of the air filter78(space that is downstream of air filter78in air flow path63) is a clean chamber80that can communicate with the secondary chamber69via the valve port75.

The dust in the air is captured by the air filter78during a process in which the pressure in the fuel tank11becomes a negative pressure, the negative pressure valve70is opened, and air flowing into the introducing chamber79(primary chamber67) via the introducing port71passes through the air filter78. Therefore, clean air mixed with substantially no dust flows into the clean chamber80. Accordingly, there is no possibility that the dust is caught between the opening edge of the valve port75and the valve body76when the negative pressure valve70is closed.

The fuel supply device59according to Example 4 includes the inlet pipe12configured such that a first end of the inlet pipe12is connected to the oil supply port13and a second end of the inlet pipe12is connected to the fuel tank11and the air flow path63configured such that an upstream side end of the air flow path63is open to the outside and a downstream side end of the air flow path63is connected to the fuel tank11. The air flow path63includes the negative pressure valve70configured such that the valve body is moved and the valve port is opened when the pressure in the fuel tank11becomes a negative pressure and the air filter78disposed upstream of the valve port75(secondary chamber69) of the negative pressure valve70.

In the case of the above-described configuration, air in the atmosphere flows into the fuel tank11after sequentially passing through the air filter78and the negative pressure valve70when the negative pressure valve70is opened. However, the dust in the atmosphere does not reach the negative pressure valve70since the dust cannot pass through the air filter78. Therefore, it is possible to prevent a malfunction of the negative pressure valve70that occurs when the dust in the atmosphere is caught.

The negative pressure valve70and the air filter78are integrated with each other via the housing65and constitute the valve module64. The valve module64is detachable from the breather pipe60that constitutes the air flow path63. Therefore, at the time of maintenance of the air filter78or the negative pressure valve70, it is possible to detach the housing65of the valve module64from the breather pipe60by loosening the fastening member. Since the housing65is obtained by assembling and combining a plurality of members, the air filter78or the negative pressure valve70can be detached when the housing65is disassembled. Therefore, the workability at the time of maintenance is favorable.

The negative pressure valve70is provided such that air flows into a space positioned radially inward of the breather pipe60from a space positioned radially outward of the breather pipe60(primary chamber67) via the secondary chamber69. The air filter78is disposed in an approximate arc shape to cover the outer circumference of the breather pipe60and the negative pressure valve70. In the case of the above-described configuration, it is possible to achieve space-saving in comparison with a case where the negative pressure valve70and the air filter78are provided to protrude in the radial direction from the outer circumference of the breather pipe60.

Example 5 which is a specific example of the aspect of the disclosure will be described with reference toFIGS. 8 and 9. Regarding the vertical direction, directions inFIG. 8will be referred to as upward and downward directions in the following description.

A fuel supply device83in Example 5 is provided with the fuel tank11, the inlet pipe12for supplying fuel to the fuel tank11, the fuel cap14that opens and closes the oil supply port13of the inlet pipe12, the breather pipe60through which air in the fuel tank11is discharged to the outside while oil is being supplied, the canister pipe61, and the valve module64. In a state where the fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed.

A lower end portion of the islet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11. An upper end portion of the breather pipe60is connected to a portion of the inlet pipe12that is positioned slightly below the oil supply port13(positioned downstream of oil supply port13in oil supply path) such that the upper end portion communicates with the inlet pipe12. The lower end portion of the breather pipe60is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11.

In Example 4, the valve module64is attached to the breather pipe60. However, in Example 5, the valve module64having the same configuration as that in Example 4 is attached to the inlet pipe12. An upper end portion of the canister pipe61is connected to a lower surface of the valve module64. The valve module64and an area from the valve module64of the inlet pipe12to the fuel tank11constitute an air flow path84for causing air in the atmosphere to flow into the fuel tank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure).

The valve module64is configured to include the housing65, the normally closed negative pressure valve70, the air filter78, and the attachment member81. The negative pressure valve70and the air filter78are integrated with the housing65. The housing65is configured to include the primary side casing66in which the primary chamber67of the negative pressure valve70is formed and the secondary side casing68in which the secondary chamber69of the negative pressure valve70is formed. The shape of the primary side casing66as seen in a plan view is an approximate semi-arc shape. The radius of curvature of an inner circumference of the approximate semi-arc shape is equal to the outer diameter of the inlet pipe12. The secondary side casing68protrudes from the inner circumference of the primary side casing66.

The housing65is fixed to the inlet pipe12by the plate-shaped attachment member81that has an approximate semi-arc shape as seen in a plan view. In a state where the housing65is fixed to the inlet pipe12, the primary side casing66and the attachment member81are in close-contact with the outer circumference of the inlet pipe12and the inlet pipe12is interposed between the primary side casing66and the attachment member81in the radial direction. In addition, opposite end portions of the primary side casing66and the attachment member81in the circumferential direction are fixed to each other by a fastening member (not shown) such as a bolt and a nut. The secondary side casing68is air-tightly fitted into the attachment hole82that is formed in the inlet pipe12such that the attachment hole82penetrates the inlet pipe12and the secondary side casing68faces the inside of the inlet pipe12.

The primary chamber67and the secondary chamber69constitute the air flow path84along with the inlet pipe12. The introducing port71that penetrates the first circumferential end portion of the outer circumferential wall portion of the primary side casing66such that the primary chamber67communicates with the atmosphere is formed in the primary side casing66. The communication port72and the water drain port74are formed in the second circumferential end portion of the lower wall portion of the primary side casing66such that the communication port72and the water drain port74penetrate the second circumferential end portion. The retaining wall portion73that protrudes toward the primary chamber67side (upper side) is formed over the entire circumference of the opening edge of the communication port72.

The upper end portion of the canister pipe61is air-tightly connected to me communication port72. The canister62is provided in the middle of the canister pipe61. The lower end portion of the canister pipe61is connected to the fuel tank11. Fuel vapor that is generated in the fuel tank11while oil is being supplied is adsorbed by activated carbon in the canister62so that clean air is discharged to the atmosphere through the canister pipe61and the introducing port71of the valve module64. When the fuel vapor adsorbed in the canister62is released through a negative-pressure purging process of an engine (not shown), the pressure in the canister62becomes a negative pressure so that the outside air is taken into the canister62via the introducing port7after passing through the valve module64and the canister pipe61.

The valve port75for causing the primary chamber67and the secondary chamber69to communicate with each other is formed in the inner circumferential wall portion of the primary side casing66. In the secondary chamber69, the valve body76for opening and closing the valve port75and the spring member77that urges the valve body76in the valve closing direction are accommodated. The secondary chamber69communicates with the inlet pipe12. In a usual state, the valve body76air-lightly closes the valve port75due to an urging force of the spring member77so that the negative pressure valve70is maintained in a closed state in which the primary chamber67and the secondary chamber69are air-tightly isolated from each other.

When the pressure in the secondary chamber69(in fuel tank11) becomes lower than the pressure in the primary chamber67, the valve body76moves against the urging force of the spring member77in a direction such that the valve port75is opened. Therefore, the primary chamber67and the secondary chamber69communicate with each other and the negative pressure valve70enters an opened state. When the negative pressure valve70enters the opened state, air in the atmosphere is introduced into the primary chamber67via the introducing port71and the air flows into the fuel tank11after sequentially passing through the valve port75, the secondary chamber69, and the inlet pipe12.

Since dust floats in the atmosphere (air), when the negative pressure valve70is opened, the dust flows into the primary chamber67along with the air. In a case where the dust adheres to the valve port75or the valve body76of the negative pressure valve70, the negative pressure valve70may not be fully closed because the dust is caught between an opening edge of the valve port75and the valve body76when the negative pressure valve70is closed.

As a countermeasure for the above-described problem, the primary chamber67in the fuel supply device83according to Example 5 is partitioned into an inner circumferential space and an outer circumferential space by the bellows-shaped air filter78that is disposed in the circumferential direction. The air filter78allows the atmospheric air (air) to pass through the air filter78while the air filter78inhibits the dust in the atmosphere from passing through the air filter78. A space in the primary chamber67that is positioned radially outward of the air filter78(space that is upstream of air filter78in air flow path84) is the introducing chamber79that is open to the atmosphere at the introducing port71. A space in the primary chamber67that is positioned radially inward of the air filter78(space that is downstream of air filter78in air flow path84) is the clean chamber80that can communicate with the secondary chamber69via the valve port75.

The dust in the air is captured by the air filter78during a process in which the pressure in the fuel tank11becomes a negative pressure, the negative pressure valve70is opened, and air flowing into the introducing chamber79(primary chamber67) via the introducing port71passes through the air filter78. Therefore, clean air mixed with substantially no dust flows into the clean chamber80. Accordingly, there is no possibility that the dust is caught between the opening edge of the valve port75and the valve body76when the negative pressure valve70is closed.

The fuel supply device83according to Example 5 includes the inlet pipe12configured such that a first end of the inlet pipe12is connected to the oil supply port13and a second end of the inlet pipe12is connected to the fuel tank11and the air flow path84configured such that an upstream side end of the air flow path84is open to the outside and a downstream side end of the air flow path84is connected to the fuel tank11. The air flow path84includes the negative pressure valve70configured such that the valve body is moved and the valve port is opened when the pressure in the fuel tank11becomes a negative pressure and the air filter78disposed upstream of the valve port75(secondary chamber69) of the negative pressure valve70.

In the case of the above-described configuration, air in the atmosphere flows into the fuel tank11after sequentially passing through the air filter78and the negative pressure valve70when the negative pressure valve70is opened. However, the dust in the atmosphere does not reach the negative pressure valve70since the dust cannot pass through the air filter78. Therefore, it is possible to prevent a malfunction of the negative pressure valve70that that occurs when the dust in the atmosphere is caught.

The negative pressure valve70and the air filter78are integrated with each other via the housing65and constitute the valve module64. The valve module64is detachable from the inlet pipe12that constitutes the air flow path84. Therefore, at the time of maintenance of the air filter78or the negative pressure valve70, it is possible to detach the housing65of the valve module64from the inlet pipe12by loosening the fastening member. Since the housing65is obtained by assembling and combining a plurality of members, the air filter78or the negative pressure valve70can be detached when the housing65is disassembled. Therefore, the workability at the time of maintenance is favorable.

The negative pressure valve70is provided such that air flows into a space positioned radially inward of the inlet pipe12from a space positioned radially outward of the inlet pipe12(primary chamber67) via the secondary chamber69. The air filter78is disposed in an approximate arc shape to cover the outer circumference of the inlet pipe12and the negative pressure valve70. In the case of the above-described configuration, it is possible to achieve space-saving in comparison with a case where the negative pressure valve70and the air filter78are provided to protrude in the radial direction from the outer circumference of the inlet pipe12.

Example 6 which is a specific example of the aspect of the disclosure will be described with reference toFIGS. 10 and 11. Regarding the vertical direction, directions inFIGS. 10 and 11will be referred to as upward and downward directions in the following description. Regarding the horizontal direction, directions inFIGS. 10 and 11will be referred to as rightward and leftward directions.

A fuel supply device85in Example 6 is provided with the fuel tank11, the inlet pipe12for supplying fuel to the fuel tank11, the fuel cap14that opens and closes the oil supply port13of the inlet pipe12, a normally closed negative pressure valve86, and a filter unit100. A lower end portion of the inlet pipe12(downstream side end of oil supply path) is connected to the fuel tank11such that the lower end portion communicates with the fuel tank11. In a state where the fuel cap14is attached to the inlet pipe12, the oil supply port13is air-tightly closed.

A cylindrical portion87of which an axis is approximately parallel to the horizontal direction (direction approximately orthogonal to axis of upper end portion of inlet pipe12) is formed to integrally protrude in a radially outward direction (leftward) on the outer circumference of an upstream side end portion (position near oil supply port13) of the inlet pipe12. The cylindrical portion87constitutes the negative pressure valve86. A first seal ring88that air-tightly seals a gap between the cylindrical portion87and a valve cap91(which will be described later) is mounted onto a protruding end surface (left end surface) of the cylindrical portion87. An engagement projection89is formed over the entire outer circumference of a protruding end portion of the cylindrical portion87. The internal space of the cylindrical portion87is a secondary chamber90that communicates with the inside of the inlet pipe12(fuel inflow path).

The valve cap91constituting the negative pressure valve86is attached to the protruding end portion of the cylindrical portion87. The valve cap91is a single component that includes an annular plate-shaped main body portion92, a cylindrical fitting portion93, and a plurality of elastic engagement pieces94. An outer circumferential edge portion of the plate-shaped main body portion92functions as a flange-shaped locking portion95. The cylindrical fitting portion93protrudes leftward from a hole edge of a central hole of the plate-shaped main body portion92such that the cylindrical fitting portion93becomes coaxial with the cylindrical portion87. The central hole of the plate-shaped main body portion92and the internal space of the cylindrical fitting portion93function as a valve port96of the negative pressure valve86. The elastic engagement pieces94protrude toward a side opposite to the cylindrical tilting portion93side (rightward) from the plate-shaped main body portion92in a cantilevered state and are disposed at intervals in the circumferential direction on a circumference coaxial with the valve port96.

The valve cap91is attached to the cylindrical portion87with the plate-shaped main body portion92abutting onto the protruding end surface of the cylindrical portion87and the elastic engagement pieces94being engaged with the engagement projection89of the cylindrical portion87. The valve cap91and the cylindrical portion87constitute a valve housing97. It is possible to detach the valve cap91from the cylindrical portion87by elastically deforming the elastic engagement pieces94radially outward and releasing the elastic engagement pieces94from the engagement projection89. In a state where the valve cap91is attached to the cylindrical portion87, the outer circumference of the inlet pipe12, the cylindrical portion87, and the valve cap91constitute the secondary chamber90. In the secondary chamber90, a valve body98that opens and closes the valve port96and a spring member99that urges the valve body98in a valve closing direction are accommodated.

The filter unit100is obtained by accommodating an air filter110in a filter housing101. The inside of the filter housing101is a primary chamber304that constitutes the negative pressure valve86. The primary chamber104, the secondary chamber90, and an area from a portion of the inlet pipe12at which the inlet pipe12communicates with the cylindrical portion87to the fuel tank11constitute an air flow path105for causing air in the atmosphere to flow into the fuel lank11in a case where the pressure in the fuel tank11becomes a negative pressure (becomes lower than atmospheric pressure).

An introducing port106that penetrates an outer wall of the filter housing101and through which the primary chamber104and the atmosphere communicate with each other is formed in a lower end portion of the primary chamber104(upstream side end portion of air flow path105). A fitting hole107that penetrates the outer wall of the filter housing101and through which the inside of the primary chamber104and the outside of the filter housing101communicate with each other is formed in an upper end portion of the primary chamber104. A second seal ring108that air-tightly seals a gap between the filter housing101and the valve cap91is mounted onto an area on an outer surface of the filter housing101that coaxially surrounds the filling hole107. On the outer surface of the filter housing101, a plurality of elastic locking pieces109is formed to protrude in a cantilevered state. The elastic locking pieces109are disposed to coaxially surround the second seal ring108.

When the filter unit100is attached to the valve housing97(position near oil supply port13of inlet pipe12), the negative pressure valve86is configured. In a state where the filter housing101is attached to the valve housing97, the fitting hole107is fitted onto the cylindrical tilting portion93and the area (upper end portion of right surface) on the outer surface of the filter housing101onto which the second seal ring108is mounted abuts onto the plate-shaped main body portion92of the valve cap91. When the elastic locking pieces109are engaged with the locking portion95, the filter unit100is locked with respect to the valve housing97in a state of being attached. It is possible to detach the filter unit100from the valve housing97by elastically deforming the elastic locking pieces109radially outward and releasing the elastic locking pieces109from the locking portion95.

In a usual state, the valve body98air-tightly closes the valve port96due to an urging force of the spring member99so that the negative pressure valve86is maintained in a closed state in which the primary chamber104and the secondary chamber90are air-tightly isolated from each other. When the pressure in the secondary chamber90(in fuel tank11) becomes lower than the pressure in the primary chamber104, the valve body98moves against the urging force of the spring member99in a direction such that the valve port96is opened. Therefore, the primary chamber104and the secondary chamber90communicate with each other and the negative pressure valve86enters an opened state. When the negative pressure valve86enters the opened state, air in the atmosphere is introduced into the primary chamber104via the introducing port106and the air flows into the fuel tank11after sequentially passing through the valve port96, the secondary chamber90, and the air flow path105(inlet pipe12).

Since dust floats in the atmosphere (air), when the negative pressure valve86is opened, the dust flows into the primary chamber104along with the air. In a case where the dust adheres to the valve port96or the valve body98of the negative pressure valve86, the negative pressure valve86may not be fully closed because the dust is caught between an opening edge of the valve port96and the valve body98when the negative pressure valve86is closed.

As a countermeasure for the above-described problem, the inside of the primary chamber104in the fuel supply device85according to Example 6 is partitioned into two chambers of an introducing chamber111and a clean chamber112by the bellows-shaped air filter110. The air filter110allows the atmospheric air (air) to pass through the air filter110while the air filter110inhibits the dust in the atmosphere from passing through the air filter110. The introducing chamber111is open to the atmosphere at the introducing port106. The clean chamber112communicates with the secondary chamber90via the valve port96.

The dust in the air is captured by the air filter110during a process in which the pressure in the fuel tank11becomes a negative pressure, the negative pressure valve86is opened, and air flowing into the introducing chamber111(primary chamber104) via the introducing port106passes through the air filter110. Therefore, clean air mixed with substantially no dust flows into the clean chamber112. Accordingly, there is no possibility that the dust is caught between the opening edge of the valve port96and the valve body98when the negative pressure valve86is closed.

The fuel supply device85according to Example 6 includes the inlet pipe12configured such that a first end of the inlet pipe12is connected to the oil supply port13and a second end of the inlet pipe12is connected to the fuel tank11and the air flow path105configured such that an upstream side end of the air flow path105is open to the outside and a downstream side end of the air flow path105is connected to the fuel tank11. The air flow path105includes the negative pressure valve86configured such that the valve body is moved and the valve port is opened when the pressure in the fuel tank11becomes a negative pressure and the air filter110disposed upstream of the valve port96(secondary chamber90) of the negative pressure valve86.

In the case of the above-described configuration, air in the atmosphere flows into the fuel tank11after sequentially passing through the air tiller110and the negative pressure valve86when the negative pressure valve86is opened. However, the dust in the atmosphere does not reach the negative pressure valve86since the dust cannot pass through the air filter110. Therefore, it is possible to prevent a malfunction of the negative pressure valve86that occurs when the dust in the atmosphere is caught.

The fuel supply device85includes the valve housing97and the filter unit100. The secondary chamber90constituting the negative pressure valve86is formed in the valve housing97and the valve body98that opens and closes the valve port96is accommodated in the secondary chamber90. The primary chamber104constituting the negative pressure valve86is formed in the filter unit100and the inside of the primary chamber104is partitioned into the introducing chamber111communicating with the atmosphere and the clean chamber112facing the valve port96by the air filter110. The filter unit100is detachable from the valve housing97.

Specifically, when detaching the filter housing101from the valve housing97, what has to be done is to elastic-ally deform the elastic locking pieces109of the filter housing101and releasing the elastic locking pieces109from the locking portion95of the valve housing97. In this case, the filter unit100is replaceable. Therefore, the workability at the time of maintenance of the air filter110is favorable.

The valve housing97is configured by assembling the cylindrical portion87that accommodates the valve body98and the spring member99and the valve cap91that closes an opening portion of the cylindrical portion87. It is possible to detach the valve cap91from the cylindrical portion87by elastically deforming the elastic engagement pieces94of the valve cap91and releasing the elastic engagement pieces94from the engagement projection89of the cylindrical portion87. When the valve cap91is detached from the cylindrical portion87, it becomes possible to clean or replace the valve body98and the spring member99. Therefore, the workability at the time of maintenance of the negative pressure valve86is also favorable.

The negative pressure valve86includes the cylindrical portion87that accommodates the valve body98and the cylindrical portion87integrally protrudes in the radial direction from the outer circumference (circumferential surface) of the inlet pipe12. In the case of the above-described configuration, the number of components can be reduced in comparison with a case where the cylindrical portion87and the inlet pipe12are provided separately from each other.

Other Examples

For example, the following examples are also included in the technical scope.

(1) In Example 3, the air filter43is provided on the upstream side end portion of the canister pipe38that is significantly separated from the negative pressure valve53. However, the air filter43may be disposed at a position in the canister pipe38that is close to the negative pressure valve53.

(2) In Example 3, the cylindrical connection portion52constituting the secondary chamber56of the negative pressure valve53integrally protrudes from an outer circumference of the breather pipe37. However, the cylindrical connection portion52may integrally protrude from an outer circumference of the canister pipe38and the cylindrical connection portion52may be a member separated from both of the breather pipe37and the canister pipe38.

(3) In Example 3, the filter unit41may be detachable from the inlet pipe12.

(4) In Examples 4 and 5, the secondary side casing68constituting the secondary chamber69of the negative pressure valve70is a member separated from the breather pipe60. However, the secondary side casing may be integrally formed with the breather pipe.

(5) In Examples 4 and 5, the secondary side casing68is fitted into the breather pipe60. However, the secondary side casing may protrude radially outward from the outer circumference of the breather pipe.

(6) In Examples 4 and 5, the canister pipe61is connected to the valve module64. However, the canister pipe61may be provided in a state of not being connected to the valve module64.

(7) In Example 6, the filter unit100is provided on the inlet pipe12. However, the filter unit100may be provided on the outer circumference of the breather pipe. In this case, the internal space of the filter unit100, the internal space of the negative pressure valve86, and the internal space of the breather pipe constitute the air flow path.

(8) In Example 6, the cylindrical portion87that accommodates the valve body98of the negative pressure valve86integrally protrudes from the outer circumference of the inlet pipe12. However, in a case where the negative pressure valve86is provided on the outer circumference of the breather pipe, the cylindrical portion87of the negative pressure valve86may integrally protrude from the outer circumference of the breather pipe.

(9) In Example 6, the cylindrical portion87protrudes from the outer circumference of the inlet pipe12. However, the cylindrical portion87may integrally protrude in a racially inward direction from an inner circumference of the inlet pipe12. In a case where the negative pressure valve86is provided on the breather pipe, the cylindrical portion87may integrally protrude radially inward from the inner circumference of the breather pipe.

(10) A configuration in Example 6 in which the cylindrical portion87of the negative pressure valve86integrally protrudes from the outer circumference of the inlet pipe12can be applied as a configuration in Example 4 in which a cylindrical portion of the secondary side casing68integrally protrudes from the outer circumference of the breather pipe60and can be applied as a configuration in which the cylindrical portion of the secondary side casing68integrally protrudes from the outer circumference of the inlet pipe12in a case where the valve module64is detachable from the inlet pipe12, which is a modification example of Example 4.

(11) In Example 6, the filter housing101may be configured by air-tightly combining two detachable members. In this case, the air filter110becomes replaceable.

(12) In Example 6, the cylindrical portion87and the valve cap91are fixed to each other by the elastic engagement pieces94. However, the cylindrical portion87and the valve cap91may be integrated with each other through welding.