GB1603214A

GB1603214A - Air filter

Info

Publication number: GB1603214A
Application number: GB1337778A
Authority: GB
Original assignee: Partner AB
Current assignee: Partner AB
Priority date: 1977-04-05
Filing date: 1978-04-05
Publication date: 1981-11-18
Also published as: SE401715B; DE7810015U1

Description

(54) AIR FILTER (71) We, AKTIEBOLAGET PART NER of Fack, S431 Mölndal 1, Sweden, a Swedish company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to an air filter assembly for a gas motor or internal combustion engine, having an air intake and a motor housing member having an exterior annular face surrounding said air intake, said air filter assembly comprising a hood member provided with a plurality of holes, means for detachably securing said hood member to said.motor housing member in a position in which the rim of the hood is closely associated with said annular face, and a filter member within said hood, said filter member being arranged, to separate a first chamber which communicates with the atmosphere through said holes from a second chamber which communicates with said air intake.

When such a motor has to be operated in dusty air, the dust gradually collected in the filter may cause a clogging of the filter within a comparatively short period of operation. This risk is particularly present for motors combined with machines or tools producing large quantities of dust, for instance rock saws or concrete saws. As the filter element is hidden by the hood, the clogging of the filter is not detected until the motor falters or stops. To obtain a trouble-free operation of the motor, the filter has to be inspected frequently and, if required, cleaned or replaced. In practice, however, such an inspection routine usually is difficult to realize.

Moreover, frequent filter replacements increase the operating costs.

The invention seeks to provide an improved air filtering device of the general type above specified in which the disadvantages above referred to are eliminated or substantially reduced.

According to the present invention, there is provided an air filter arrangement for a gas or internal combustion engine having an air intake and a motor housing member having an exterior annular face surrounding said air intake, said air filter arrangement including a hood comprising a perforated cylindrical sheet metal member and an airtight sheet metal top cover, means for detachably securing the hood to the motor housing member in a position in which the rim of the hood is closely associated with the said annular face, a first filter member located within the hood and arranged to separate a first chamber, which communicates with the atmosphere through the perforations of said cylindrical sheet metal member, from a second chamber for communication with the air intake, a second filter member comprising a cover of filter material fitted on the outside or inside of said cylindrical sheet metal member so as to cover the perforations thereof and a third filter member which is cupshaped, the open end of the third filter member being adapted to be fitted on the rim of the said air intake, and, in use, extending into the said second chamber.

The bottom edge of the cylindrical sheet metal member may engage a rim portion of a washer intended to rest on the said annular face and the first filter member may comprise a generally cylindrical filter unit substantially coaxial with the cylindrical sheet metal member and axially clamped between the airtight top cover and the washer.

In order that the invention and its various other preferred features may be understood more easily, an embodiment thereof will now be described, by way of example only, with reference to the drawings, in which: Figure 1 is a vertical cross sectional view of a filter arrangement constructed in accordance with the invention, and Figure 2 is a cross sectional view taken along the broken line II--II of Figure 1.

The filter arrangement of Figures 1 and 2 is mounted on a motor housing member 3 enclosing an air cooled motor cylinder 17 represented in schematical outline only. The motor housing member 3 is provided with an orifice 18 through which an upper end l5a of an air intake tube 15 of the motor ex tends. The lower end of said air intake tube 15 is connected to the carburettor of the motor. An annular sealing member 22 is clamped between the rim of the orifice 18 and a flange 15b provided on the intake tube 15.

The filter arrangement shown includes a hood consisting of a perforated cylindrical sheet metal member 2 and a flat sheet metal top cover 1. The lower edge of the cylindrical member 2 engages the outer rim of a sheet metal washer 4 resting on a plane annular supporting face 19 provided on the motor housing member 3 and surrounding the orifice 18. A pressed-out annular ridge 5 of the washer 4 serves to maintain the cylindrical member 2 and the washer 4 in the proper position with respect to each other. A finger nut 6 engaging a threaded upper end of a stud 7 attached to the motor housing member 3 and extending through a hole in the top cover 1 serves to maintain the hood 1, 2 in engagement with the washer 4 by clamping the top cover 1 against a nut 8 provided on the stud 7. A tubular spacer 9 on the stud 7 serves to define the axial position of said nut.

A generally annular filter unit consisting of a filter body 10 and a pair of end rings 11, 12 attached to said filter body is clamped between the top cover 1 and the washer 4.

The filter unit 10, 11, 12 divides the interior of the hood into an outer chamber 20 confined between the filter unit and the perforated wall of the cylindrical member 2 and an inner chamber 21 surrounded by the filter unit. The upper end ring 11 engages the bottom of a shallow groove 13 in the top cover 1. The lower end ring 12 engages the ridge 5 of the washer 4. The filter body 10 may be of any suitable type. For instance, the filter body may consist of a zigzag creased band. The elasticity of the filter body in the axial direction has to be sufficient for the maintaining of an adequate engagement pres sure between the end rings 11, 12 and the top cover 1 and the washer 4, respectively.

The outside of the cylindrical member 2 is covered by a band or sheet 14 of a filter material, for instance porous paper or nonwoven cloth or some other textile fabric. Said band or sheet 14, which serves as a prefilter, may for instance be an annular member kept in engagement with the annular hood part 2 by its own elasticity or the elasticity of an inserted piece of resilient material. The band may also form an open length mounted on the hood part 2 by attaching the two ends to each other by any suitable means e.g. by members such as hooks and eyelets, or by means of an adhesive.

The inner filter chamber 21 enclosed by the filter body 10 communicates with the air intake tube 15 through the aperture of the washer 4. A cup-shaped filter element 16 extending into the chamber surrounded by the filter body 10 is attached to the upper end 15a of the air intake tube 15. Said filter element 16 may for instance consist of a hose or close-meshed fibre flock coated wire netting, the upper end of which is closed by folding. The filter element 16 has for its peripheral purpose to prevent lumps or particles of dirt which may be detached from the filter unit 10, 11, 12 during a replacement operation from entering the air intake tube 15.

During operation of the motor, the motor housing member is heated by the radiation emitted by the top portion of the cylinder 17. Consequently also the hood 1, 2 and the filter elements associated therewith are maintained at a temperature exceeding the temperature of the surrounding air. The temperature increase has the useful effect of speeding up the vaporization of humidity which may condense on the filter elements when the motor is operated outdoors in rainy or snowy weather.

The invention is not limited to the embodiment described but also comprises, for instance, embodiments in which the filter body 10 is permanently attached to the perforated hood part 2, in which case said part 2, or the complete hood 1, 2, is disposable along with the filter body.

It will be appreciated that the filter arrangement is suitable for use with any type of internal combustion engine which requires a supply of air for its operation.

Although the filter body 10 is circular in the embodiment described other shapes of body are possible, for example rectangular.

The band of filter material 14 could be fitted to the inner wall of the cylindrical member 2.

WHAT WE CLAIM IS: 1. An air filter arrangement for a gas or internal combustion engine having an air intake and a motor housing member having an exterior annular face surrounding said air intake, said air filter arrangement including a hood comprising a perforated cylindrical sheet metal member and an airtight sheet metal top cover, means for detachably securing the hood to the motor housing member in a position in which the rim of the hood is closely associated with the said annular face, a first filter member located within the hood and arranged to separate a first chamber, which communicates with the atmosphere through the perforations of said cylindrical shet metal member, from a second chamber for communication with the air intake, a second filter member comprising a cover of filter material fitted on the outside or inside of said cylindrical sheet metal member so as to cover the perforations thereof and a third filter member which is cup shaped, the open

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

tends. The lower end of said air intake tube

15 is connected to the carburettor of the motor. An annular sealing member 22 is clamped between the rim of the orifice 18 and a flange 15b provided on the intake tube 15.

The filter arrangement shown includes a hood consisting of a perforated cylindrical sheet metal member 2 and a flat sheet metal top cover 1. The lower edge of the cylindrical member 2 engages the outer rim of a sheet metal washer 4 resting on a plane annular supporting face 19 provided on the motor housing member 3 and surrounding the orifice 18. A pressed-out annular ridge 5 of the washer 4 serves to maintain the cylindrical member 2 and the washer 4 in the proper position with respect to each other. A finger nut 6 engaging a threaded upper end of a stud 7 attached to the motor housing member 3 and extending through a hole in the top cover 1 serves to maintain the hood 1, 2 in engagement with the washer 4 by clamping the top cover 1 against a nut 8 provided on the stud 7. A tubular spacer 9 on the stud 7 serves to define the axial position of said nut.

A generally annular filter unit consisting of a filter body 10 and a pair of end rings 11, 12 attached to said filter body is clamped between the top cover 1 and the washer 4.

The filter unit 10, 11, 12 divides the interior of the hood into an outer chamber 20 confined between the filter unit and the perforated wall of the cylindrical member 2 and an inner chamber 21 surrounded by the filter unit. The upper end ring 11 engages the bottom of a shallow groove 13 in the top cover 1. The lower end ring 12 engages the ridge 5 of the washer 4. The filter body 10 may be of any suitable type. For instance, the filter body may consist of a zigzag creased band. The elasticity of the filter body in the axial direction has to be sufficient for the maintaining of an adequate engagement pres sure between the end rings 11, 12 and the top cover 1 and the washer 4, respectively.

The outside of the cylindrical member 2 is covered by a band or sheet 14 of a filter material, for instance porous paper or nonwoven cloth or some other textile fabric. Said band or sheet 14, which serves as a prefilter, may for instance be an annular member kept in engagement with the annular hood part 2 by its own elasticity or the elasticity of an inserted piece of resilient material. The band may also form an open length mounted on the hood part 2 by attaching the two ends to each other by any suitable means e.g. by members such as hooks and eyelets, or by means of an adhesive.

The inner filter chamber 21 enclosed by the filter body 10 communicates with the air intake tube 15 through the aperture of the washer 4. A cup-shaped filter element 16 extending into the chamber surrounded by the filter body 10 is attached to the upper end 15a of the air intake tube 15. Said filter element 16 may for instance consist of a hose or close-meshed fibre flock coated wire netting, the upper end of which is closed by folding. The filter element 16 has for its peripheral purpose to prevent lumps or particles of dirt which may be detached from the filter unit 10, 11, 12 during a replacement operation from entering the air intake tube 15.

During operation of the motor, the motor housing member is heated by the radiation emitted by the top portion of the cylinder 17. Consequently also the hood 1, 2 and the filter elements associated therewith are maintained at a temperature exceeding the temperature of the surrounding air. The temperature increase has the useful effect of speeding up the vaporization of humidity which may condense on the filter elements when the motor is operated outdoors in rainy or snowy weather.

The invention is not limited to the embodiment described but also comprises, for instance, embodiments in which the filter body 10 is permanently attached to the perforated hood part 2, in which case said part 2, or the complete hood 1, 2, is disposable along with the filter body.

It will be appreciated that the filter arrangement is suitable for use with any type of internal combustion engine which requires a supply of air for its operation.

Although the filter body 10 is circular in the embodiment described other shapes of body are possible, for example rectangular.

The band of filter material 14 could be fitted to the inner wall of the cylindrical member 2.

WHAT WE CLAIM IS: 1. An air filter arrangement for a gas or internal combustion engine having an air intake and a motor housing member having an exterior annular face surrounding said air intake, said air filter arrangement including a hood comprising a perforated cylindrical sheet metal member and an airtight sheet metal top cover, means for detachably securing the hood to the motor housing member in a position in which the rim of the hood is closely associated with the said annular face, a first filter member located within the hood and arranged to separate a first chamber, which communicates with the atmosphere through the perforations of said cylindrical shet metal member, from a second chamber for communication with the air intake, a second filter member comprising a cover of filter material fitted on the outside or inside of said cylindrical sheet metal member so as to cover the perforations thereof and a third filter member which is cup shaped, the open

end of the third filter member being adapted to be fitted on the rim of the said air intake, and, in use, extending into the said second chamber.
2. A filter arrangement as claimed in Claim 1, wherein the bottom edge of the cylindrical sheet metal member engages a rim portion of a washer intended to rest on the said annular face and wherein the first filter member comprises a generally cylindrical fiter unit substantially coaxial with the cylindrical sheet metal member and when in use, axially clamped between the airtight top cover and the washer.
3. An air filter arrangement substantially as described herein with reference to, or as illustrated in, the drawings.
4. An assembly of an air filter arrangement as claimed in any one of the claims 1 to 3 with a gas or internal combustion engine having an air intake and a motor housing member having an exterior annular face surrounding the air intake.