KR20030012606A - Filter apparatus of fuel pump - Google Patents

Filter apparatus of fuel pump Download PDF

Info

Publication number
KR20030012606A
KR20030012606A KR1020010046722A KR20010046722A KR20030012606A KR 20030012606 A KR20030012606 A KR 20030012606A KR 1020010046722 A KR1020010046722 A KR 1020010046722A KR 20010046722 A KR20010046722 A KR 20010046722A KR 20030012606 A KR20030012606 A KR 20030012606A
Authority
KR
South Korea
Prior art keywords
fuel
filter
pump
fuel pump
fuel filter
Prior art date
Application number
KR1020010046722A
Other languages
Korean (ko)
Other versions
KR100461443B1 (en
Inventor
신영귀
Original Assignee
현대자동차주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 현대자동차주식회사 filed Critical 현대자동차주식회사
Priority to KR10-2001-0046722A priority Critical patent/KR100461443B1/en
Publication of KR20030012606A publication Critical patent/KR20030012606A/en
Application granted granted Critical
Publication of KR100461443B1 publication Critical patent/KR100461443B1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/077—Fuel tanks with means modifying or controlling distribution or motion of fuel, e.g. to prevent noise, surge, splash or fuel starvation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/073—Tank construction specially adapted to the vehicle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/04—Feeding by means of driven pumps

Abstract

PURPOSE: A fuel filter structure of a fuel pump is provided to extend mileage of a vehicle to the utmost by using even fuel remaining in the corners of a reservoir cup when traveling on a slope way, with insufficiency of fuel. CONSTITUTION: In a fuel filter structure of a fuel pump, an end of a flexible hose(23) is connected to the lower part of a plastic pipe(21) communicated with a fuel pump(20). An auxiliary fuel filter(24) is formed at the other end of the flexible hose. Accordingly, if the oil level of fuel is under a fuel filter(23) housed in a reservoir cup(15) when traveling on a slope way, with insufficiency of fuel in a fuel tank(10), the auxiliary fuel filter is moved by self-weight toward the inclined side and fuel remaining in the reservoir cup is pumped.

Description

연료펌프의 연료 필터구조{Filter apparatus of fuel pump}Fuel filter structure of fuel pump

본 발명은 연료펌프의 연료 필터구조에 관한 것으로, 보다 상세하게는 연료탱크 내에 연료가 충분하지 않은 상태에서 경사로를 주행하게 되는 경우에 리저버 컵 내에 잔류되는 연료가 연료펌프로 흡입될 수 있도록 별도의 연료필터가 플렉시블한 호스로써 연결되는 연료펌프의 연료 필터구조에 관한 것이다.The present invention relates to a fuel filter structure of a fuel pump, and more particularly, when the fuel running in the inclined state when there is not enough fuel in the fuel tank, the fuel remaining in the reservoir cup can be sucked into the fuel pump. A fuel filter structure of a fuel pump is connected to the fuel filter by a flexible hose.

일반적으로 엔진은 연료를 연소시켜 운전되는 것으로서 차량의 일측에는 연료가 저장되는 연료탱크가 장착되어진다. 그리고 연료탱크 내부에는 저장된 연료를 고압으로 엔진의 딜리버리 파이프로 공급하여 인젝터에서 실린더 내부로 연료가 분사되도록 하는 연료펌프가 형성되어 있다. 또한, 상기 연료펌프의 하부에는 연료에 혼합되어 있는 이물질을 여과하여 연료펌프 내부로 이송되지 않게 하여 이물질에 의한 내구성 문제 및 소음이 발생되는 것을 방지하기 위한 연료필터가 형성되어 있다. 또한, 연료탱크 내에 연료가 충분하지 않은 상태에서 경사로를 주행하는 경우에 원활한 연료의 공급을 위해서 리저버 컵이 형성되어 있다.In general, the engine is operated by burning fuel, and one side of the vehicle is equipped with a fuel tank for storing fuel. In addition, a fuel pump is formed in the fuel tank to supply the stored fuel to the delivery pipe of the engine at high pressure so that fuel is injected from the injector into the cylinder. In addition, a lower portion of the fuel pump is provided with a fuel filter for filtering foreign matters mixed in the fuel so as not to be transported into the fuel pump to prevent durability problems and noise caused by foreign matters. In addition, a reservoir cup is formed to smoothly supply fuel when traveling on a slope in a state where there is not enough fuel in the fuel tank.

도 4는 상기한 바와 같은 연료탱크의 단면도로서, 소정 용적의 저장공간을 갖는 연료탱크(10)의 상부 일측에는 연료를 주유하기 위한 연료주입관(11)이 형성되고, 다른 일측에는 엔진으로 연료가 이송되기 위한 이송관(12)이 형성된다.4 is a cross-sectional view of the fuel tank as described above, a fuel injection pipe 11 for supplying fuel is formed on one side of the fuel tank 10 having a storage space of a predetermined volume, and the other side is fueled by the engine. Transfer pipe 12 is formed to be transported.

상기 연료 이송관(12)은 연료탱크(10) 내부에 형성되는 연료펌프(13)의 일측과 연결되며, 상기 연료펌프(13)의 하단에는 연료 중의 이물질을 거르기 위한 연료필터(14)가 리저버 컵(15)의 내부 하측에 형성된다. 상기 연료필터(14)는 플라스틱 파이프(14a)로써 연료펌프(13)의 하측에 연결된다.The fuel transfer pipe 12 is connected to one side of the fuel pump 13 formed in the fuel tank 10, the fuel filter 14 for filtering foreign substances in the fuel at the lower end of the fuel pump 13 reservoir It is formed in the inner lower side of the cup 15. The fuel filter 14 is connected to the lower side of the fuel pump 13 by a plastic pipe 14a.

상기한 연료펌프(13)은 전자제어장치(ECU)의 제어신호가 모터에 전달되어 펌핑되는 연료량이 제어되는데, 이렇게 펌핑된 연료는 강하게 엔진까지 공급되어 연소실로 분사되며, 연소실로 분사되지 않고 잉여되는 연료는 리턴라인(16)을 통해 다시 연료탱크(10)로 복귀되어진다.The fuel pump 13 transmits a control signal of an electronic control unit (ECU) to the motor to control the amount of fuel pumped. The pumped fuel is supplied to the engine strongly and injected into the combustion chamber, and is not injected into the combustion chamber. The fuel is returned to the fuel tank 10 through the return line 16.

특히, 연료탱크(10) 내에 연료가 충분하지 않을 경우에는 상기한 리저버 컵(15)에 의해서 저장되는 연료가 연료펌프(13)에 의해 펌핑되므로서 연료부족에 의한 시동이 꺼지는 것이 방지된다.In particular, when there is not enough fuel in the fuel tank 10, the fuel stored by the reservoir cup 15 is pumped by the fuel pump 13, thereby preventing starting of the fuel shortage.

그러나 종래에는 연료펌프의 하단과 연료필터가 플라스틱 파이프로써 연결되므로서, 연료탱크 내에 연료가 부족한 상태에서 경사길을 주행할 때에 연료의 유면이 연료필터의 하측에 위치되면 연료의 공급이 차단되어 시동이 꺼지게 되는 문제점이 있었다.However, conventionally, the lower end of the fuel pump and the fuel filter are connected by a plastic pipe, so when the fuel level is located below the fuel filter when driving down the slope in a state where fuel is insufficient in the fuel tank, the fuel supply is cut off and the starting is stopped. There was a problem that turned off.

따라서 본 발명은 상기와 같은 문제점을 해결하기 위해서 안출된 것으로서, 연료탱크 내에 연료가 충분하지 않은 상태에서 경사로를 주행하게 되는 경우에 리저버 컵 내에 잔류되는 연료가 연료펌프로 흡입될 수 있도록 별도의 연료필터가 플렉시블한 호스로써 연결되는 연료펌프의 연료 필터구조를 제공하는 데 목적이 있다.Accordingly, the present invention has been made in order to solve the above problems, the fuel remaining in the reservoir cup to be sucked into the fuel pump when the fuel running in the ramp in the state that there is not enough fuel in the fuel tank It is an object to provide a fuel filter structure of a fuel pump in which the filter is connected by a flexible hose.

본 발명은 상기와 같은 목적을 달성하기 위한 수단으로서,The present invention as a means for achieving the above object,

연료탱크의 내부에 일정 용적을 가지는 리저버 컵이 형성되고, 상기 리저버 컵에 수용되는 연료필터가 플라스틱 파이프에 의해서 연료펌프의 하측과 연결되는 연료탱크에 있어서,In a fuel tank in which a reservoir cup having a predetermined volume is formed inside the fuel tank, and the fuel filter accommodated in the reservoir cup is connected to the lower side of the fuel pump by a plastic pipe.

연료펌프와 연통되는 플라스틱 파이프의 하부에 플렉시블 호스의 일단이 연결되고, 상기 플렉시블 호스의 다른 일단에는 보조연료필터가 형성되므로서, 연료탱크 내에 연료가 충분하지 않은 상태에서 경사길을 주행하게 되어 연료의 유면이 상기 연료필터보다 아래에 위치될 때, 상기 보조연료필터가 자중에 의해 경사진 측으로 이동되어 리저버 컵에 잔류되는 연료를 펌핑하게 되는 것을 특징으로 한다.One end of the flexible hose is connected to the lower part of the plastic pipe communicating with the fuel pump, and an auxiliary fuel filter is formed at the other end of the flexible hose, so that the fuel tank runs on a slope in a state where there is not enough fuel. When the oil level is located below the fuel filter, the auxiliary fuel filter is characterized by being moved to the inclined side by its own weight to pump the fuel remaining in the reservoir cup.

도 1은 본 발명에 의한 연료탱크의 구성도.1 is a block diagram of a fuel tank according to the present invention.

도 2는 본 발명의 주요부를 확대도시한 도면.Figure 2 is an enlarged view of the main part of the present invention.

도 3은 본 발명에 의한 연료탱크의 작동상태도.Figure 3 is an operating state of the fuel tank according to the present invention.

도 4는 종래의 기술을 설명하기 위한 도면.4 is a diagram for explaining a conventional technology.

※ 도면의 주요부분에 대한 부호의 설명※ Explanation of code for main part of drawing

10 : 연료탱크10: fuel tank

12 : 이송관12: transfer pipe

15 : 리저버 컵15: reservoir cup

20 : 연료펌프20: fuel pump

21 : 플라스틱 파이프21: plastic pipe

22 : 연료필터22: fuel filter

23 : 플렉시블 호스23: flexible hose

24 : 보조연료필터24: auxiliary fuel filter

이하, 본 발명의 실시예를 첨부한 도면과 함께 상세하게 설명하면 다음과 같다.Hereinafter, with reference to the accompanying drawings, an embodiment of the present invention will be described in detail.

도 1은 본 발명에 의한 연료탱크의 구성도이고, 도 2는 본 발명의 주요부를 확대도시한 도면이고, 도 3은 본 발명에 의한 연료탱크의 작동상태도이다.1 is a configuration diagram of a fuel tank according to the present invention, FIG. 2 is an enlarged view of a main part of the present invention, and FIG. 3 is an operation state diagram of a fuel tank according to the present invention.

도면 중에 표시되는 도면부호 20은 본 발명에 의한 연료펌프를 지시하는 것으로, 일부의 도면부호는 종래의 기술에서 사용된 부호가 그대로 인용된다.Reference numeral 20 shown in the drawing indicates a fuel pump according to the present invention, and some of the reference numerals are referred to as symbols used in the prior art.

상기한 연료펌프(20)의 하측은 종래와 같이 플라스틱 파이프(21)가 연결되어지고, 일측으로 절곡되는 플라스틱 파이프(21)의 끝단에는 연료필터(22)가 연결된다. 상기 연료필터(22)는 연료 중에 포함된 이물질이 흡입되지 않도록 금속망으로 형성되는 것이 바람직하다.The lower side of the fuel pump 20 is connected to the plastic pipe 21 as in the prior art, the fuel filter 22 is connected to the end of the plastic pipe 21 is bent to one side. The fuel filter 22 is preferably formed of a metal mesh so that foreign substances contained in the fuel are not sucked in.

그리고 상기한 플라스틱 파이프(21)의 하측면에 플렉시블 호스(23)의 일단이 연결되는데, 이 플렉시블 호스(23)의 다른 일단에는 보조연료필터(24)가 연결된다. 상기 보조연료필터(24)는 상기 연료필터(22)와 마찬가지로 연료 중의 이물질이 여과될 수 있도록 금속망으로 형성되는 것이 바람직하다.One end of the flexible hose 23 is connected to the lower side of the plastic pipe 21, and the other end of the flexible hose 23 is connected to the auxiliary fuel filter 24. Like the fuel filter 22, the auxiliary fuel filter 24 is preferably formed of a metal mesh so that foreign substances in the fuel can be filtered.

특히, 상기한 플렉시블 호스(23)의 길이는 플라스틱 파이프(21)의 길이보다 길게 형성되어 리저버 컵(15)의 구석부까지 위치되는 것이 바람직하며, 플렉시블 호스(23)의 직경은 플라스틱 파이프(21)의 직경보다 작아도 된다. 그리고 상기 플렉시블 호스(23)는 차량이 일측으로 기울어질 경우에 보조연료필터(24)의 자중에 의해서 낮은 쪽으로 위치가 이동될 수 있을 정도로 유연한 것이 바람직하다.In particular, the length of the flexible hose 23 is formed longer than the length of the plastic pipe 21 is preferably located to the corner of the reservoir cup 15, the diameter of the flexible hose 23 is a plastic pipe 21 May be smaller than the diameter. And the flexible hose 23 is preferably flexible enough to be moved to the lower position by the weight of the auxiliary fuel filter 24 when the vehicle is inclined to one side.

이상과 같이 구성되는 본 발명의 작동을 설명하면 다음과 같다.Referring to the operation of the present invention configured as described above are as follows.

엔진이 시동되면 전자제어장치의 제어신호에 의해 작동되는 모터에 의해서 연료펌프(13)는 리저버 컵(15) 내의 연료를 흡입한 후 이송관(12)을 통해 연소실로 압송하게 된다.When the engine is started, the fuel pump 13 sucks the fuel in the reservoir cup 15 by the motor operated by the control signal of the electronic controller and then feeds the fuel into the combustion chamber through the transfer pipe 12.

그런데 운행 중에 연료탱크(10) 내의 연료가 부족하여 연료의 유면이 상기한 연료필터(22)보다 낮게 되는 경우가 발생되면 리저버 컵(15) 내에 연료가 잔류하더라도 상기 연료필터(22)로는 연료의 공급이 이루어지지 못한다.However, if the fuel level in the fuel tank 10 is insufficient during operation and the oil level is lower than the fuel filter 22 described above, even if fuel remains in the reservoir cup 15, the fuel filter 22 may not be used. Supply is not made.

이 때, 상기한 보조연료필터(24)는 그 자중에 의해서 경사진 측으로 위치가 이동되므로서, 상기한 리저버 컵(15) 내부에 잔류되는 연료가 연료펌프(20)에 의해서 펌핑된다.At this time, the auxiliary fuel filter 24 is moved to the inclined side by its own weight, so that the fuel remaining in the reservoir cup 15 is pumped by the fuel pump 20.

즉, 상기한 보조연료필터(24)를 연료펌프(20)와 연결하는 플렉시블 호스(23)가 유연하게 형성되기 때문에 보조연료펌프(24)의 자연스러운 위치이동이 가능하게 된다.That is, since the flexible hose 23 connecting the auxiliary fuel filter 24 to the fuel pump 20 is flexibly formed, the natural position of the auxiliary fuel pump 24 can be moved.

따라서 상기와 같이 플렉시블 호스(23)로 연결되는 보조연료필터(24)를 연료탱크에 형성하게 되므로서, 연료탱크(20) 내에 연료가 부족한 상태에서 차량의 주행거리를 연장할 수 있게 된다.Therefore, since the auxiliary fuel filter 24 connected to the flexible hose 23 is formed in the fuel tank as described above, the running distance of the vehicle can be extended in a state in which fuel is insufficient in the fuel tank 20.

상기와 같이 구성되는 본 발명은 연료탱크 내에 연료가 부족한 상태에서 경사길을 주행하게 되는 경우에 리저버 컵의 구석부에 잔류되는 연료까지 사용할 수 있게 되므로서, 연료탱크 내에 연료가 부족한 상태에서도 차량의 주행거리를 최대한 연장할 수 있는 커다란 장점이 있는 것이다.According to the present invention configured as described above, the fuel remaining in the corner of the reservoir cup can be used even when the vehicle runs on the incline when the fuel is insufficient in the fuel tank, so that the vehicle runs even when the fuel is insufficient in the fuel tank. There is a big advantage to extending the distance as much as possible.

Claims (1)

연료탱크의 내부에 일정 용적을 가지는 리저버 컵이 형성되고, 상기 리저버 컵에 수용되는 연료필터가 플라스틱 파이프에 의해서 연료펌프의 하측과 연결되는 연료탱크에 있어서,In a fuel tank in which a reservoir cup having a predetermined volume is formed inside the fuel tank, and the fuel filter accommodated in the reservoir cup is connected to the lower side of the fuel pump by a plastic pipe. 연료펌프(20)와 연통되는 플라스틱 파이프(21)의 하부에 플렉시블 호스(23)의 일단이 연결되고, 상기 플렉시블 호스(23)의 다른 일단에는 보조연료필터(24)가 형성되므로서, 연료탱크(20) 내에 연료가 충분하지 않은 상태에서 경사길을 주행하게 되어 연료의 유면이 상기 연료필터(22)보다 아래에 위치될 때, 상기 보조연료필터(24)가 자중에 의해 경사진 측으로 이동되어 리저버 컵(15)에 잔류되는 연료를 펌핑하게 되는 것을 특징으로 하는 연료펌프의 연료 필터구조.One end of the flexible hose 23 is connected to the lower portion of the plastic pipe 21 in communication with the fuel pump 20, and the auxiliary fuel filter 24 is formed at the other end of the flexible hose 23, the fuel tank When the fuel level is not enough in the vehicle 20, and the oil level of the fuel is positioned below the fuel filter 22, the auxiliary fuel filter 24 is moved to the inclined side due to its own weight and is stored in the reservoir. The fuel filter structure of the fuel pump, characterized in that for pumping the fuel remaining in the cup (15).
KR10-2001-0046722A 2001-08-02 2001-08-02 Filter apparatus of fuel pump KR100461443B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR10-2001-0046722A KR100461443B1 (en) 2001-08-02 2001-08-02 Filter apparatus of fuel pump

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR10-2001-0046722A KR100461443B1 (en) 2001-08-02 2001-08-02 Filter apparatus of fuel pump

Publications (2)

Publication Number Publication Date
KR20030012606A true KR20030012606A (en) 2003-02-12
KR100461443B1 KR100461443B1 (en) 2004-12-14

Family

ID=27717762

Family Applications (1)

Application Number Title Priority Date Filing Date
KR10-2001-0046722A KR100461443B1 (en) 2001-08-02 2001-08-02 Filter apparatus of fuel pump

Country Status (1)

Country Link
KR (1) KR100461443B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100921294B1 (en) * 2007-10-18 2009-10-09 현대자동차주식회사 Reserver cup assembly

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6419525U (en) * 1987-07-27 1989-01-31
JPS6430832A (en) * 1987-07-27 1989-02-01 Fuji Heavy Ind Ltd Fuel tank device for automobile
JPH0237163A (en) * 1988-07-27 1990-02-07 Mitsubishi Motors Corp Fuel supply device for vehicle
KR970008760U (en) * 1995-08-31 1997-03-27 Automotive Fuel Supply
KR970035542A (en) * 1995-12-27 1997-07-22 한승준 Internal Structure of Fuel Tank for Vehicle

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100921294B1 (en) * 2007-10-18 2009-10-09 현대자동차주식회사 Reserver cup assembly

Also Published As

Publication number Publication date
KR100461443B1 (en) 2004-12-14

Similar Documents

Publication Publication Date Title
JP2002276473A (en) Fuel supply system for dimethyl ether engine
BR0106720A (en) Device for transporting fuel from a storage tank to an internal combustion engine in a motor vehicle
ATE299101T1 (en) FUEL TANK FOR MOTOR VEHICLE
KR100461443B1 (en) Filter apparatus of fuel pump
KR100999624B1 (en) High-pressure fuel supply circuit
KR100488554B1 (en) Fuel supply apparatus of fuel tank
JP2006022782A (en) Fuel supply device of engine
KR100475821B1 (en) Fuel pipe
JP6331666B2 (en) Fuel pump drive control device
KR100689295B1 (en) Apparatus for fuel tank in a heavy construction equipment
KR100453650B1 (en) Cooling apparatus for fuel in reservior cup
KR100645136B1 (en) structure of oil injection in a diesel engine
KR0135542Y1 (en) Fuel tank of an automobile
KR100435774B1 (en) Fuel supply device for preventing inflow impurities for vehicles
KR20040089856A (en) Fuel tank
KR20060019728A (en) Sucking apparatus of fuel tank
KR200234197Y1 (en) Fuel breathing device of diesel engine
KR100514889B1 (en) Fuel Tank for Vehicle
KR19990003285U (en) Fuel supply device in vehicle dual fuel tank
KR100314459B1 (en) Fuel tanks increase the use of residual fuel
KR20030008028A (en) Reservoir cup of fuel tank
KR100220476B1 (en) Fuel system
KR200240744Y1 (en) Oil Feeder
KR19980054448U (en) Fuel supply device for automobile engine
KR19990002517U (en) Automotive Fuel Supply

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E701 Decision to grant or registration of patent right
GRNT Written decision to grant
FPAY Annual fee payment

Payment date: 20081202

Year of fee payment: 5

LAPS Lapse due to unpaid annual fee