Filter cigarette inspection apparatus and inspection method

An inspection apparatus for a filter cigarette FT having a perforation line (6) in the outer circumferential surface of a filter (4) for introducing the outside air has a filter socket assembly (86) that is capable of receiving the filter (4) and includes a ring holder (124) defining in the inside an end chamber for surrounding the mouthpiece of the filter (4) and a surrounding chamber for surrounding the outer circumferential surface of the filter (4) including the perforation line (6), a guide pipe (102) for supplying a compressed fluid of the given pressure into the surrounding chamber of the ring holder (124), and a guide pipe (100) that outputs the pressure in the end chamber; and a pressure sensor for detecting the pressure outputted from the guide pipe (100) that outputs the pressure in the end chamber.

TECHNICAL FIELD

The present invention relates to a filter cigarette inspection apparatus and a filter cigarette inspection method for measurement of filter ventilation of filter cigarettes as rod-like articles.

BACKGROUND ART

The filter of a filter cigarette has a rod-like filter material and a wrapping material that envelops the filter material. One of the wrapping materials is a filter having a plurality of perforations. When the filter cigarette with a filter having perforations is smoked, air flows into the filter through the perforations, which dilutes smoke from the cigarette. As a result, nicotine and tar contained in the smoke are reduced, so that the smoker can enjoy a mild flavor.

The ratio of an air amount flowing in from the perforations to an amount of the smoke drawn by the smoker is called filter ventilation (hereinafter also simply referred to as VF). As for the above-mentioned filter cigarettes, if VFis not fixed constant for each cigarette, the cigarettes do not have a uniform flavor and vary in their qualities.

The International Organization for Standardization defines a method of measuring VF, which is carried out by a measurement standard. This measurement standard is used in manufacturing plants of filter cigarettes. More specifically, filter cigarettes are pulled out of the tobacco-manufacturing machine at a constant rate, and the VFof the pulled-out filter cigarettes is measured by the measurement standard. In short, only some of the manufactured filter cigarettes are subjected to the extraction and the inspection of VF.

The method of measuring VF, which is compliant with the ISO, however, is complicated because it is troublesome to install the measurement standard in the tobacco-manufacturing machine. Even if the measurement standard can be installed in the tobacco-manufacturing machine, it takes a lot of time to inspect the VFof each filter cigarette. Therefore, it is difficult to conduct the inspection of all the manufactured filter cigarettes by this measuring method.

The measurement standard is also used in the inspection of undesired holes made in wrapping paper. As to a filter cigarette having great VF, however, an air amount flowing in through perforations is relatively greater than the air amount flowing in through the holes made in the wrapping paper. This makes it difficult to detect the holes made in the wrapping paper without fail by using the measurement standard.

The tobacco-manufacturing machine disclosed in Japanese Patent No. 3190132 has an inspection apparatus for inspecting not VFbut total ventilation (hereinafter also simply referred to as VT) as a control index for a nicotine and tar amount. The VTis the ratio of an air amount flowing in from the perforations of wrapping paper and filter of the cigarette to an amount of the smoke drawn by the smoker.

However, this well-known inspection apparatus is not capable of directly inspecting the VF, and not capable of credibly control the nicotine and tar amount of filter cigarettes.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a new inspection apparatus and a new inspection method capable of measuring filter ventilation of filter cigarettes in a short time.

Another object of the present invention is to provide a new inspection apparatus and a new inspection method capable of reliably detecting the formation of undesired holes in wrapping paper.

To achieve the objects, according to the present invention, an inspection apparatus for a filter cigarette having a cigarette, a filter that is connected to the cigarette and has a mouthpiece end, and a ventilation area in an outer circumferential surface of the filter for introducing outside air includes a transport path that transports the filter cigarette in a direction orthogonal to an axial direction of the filter cigarette and has an inspection position interposed therein; a filter socket assembly that is disposed on one side of the transport path and is allowed to be connected to the filter cigarette when the filter cigarette passes through the inspection position, the filter socket assembly including a socket that is capable of receiving the filter and defines in the inside thereof a first airtight chamber for enclosing the mouthpiece end of the filter and a second airtight chamber for enclosing the outer circumferential surface of the filter including the ventilation area, a lateral input path for supplying the second airtight chamber of the socket with a compressed fluid of a given pressure, and an output path that outputs a pressure in the first airtight chamber; and a pressure sensor for detecting the pressure outputted from the output path.

According to the above-described inspection apparatus, it is possible to inspect filter cigarettes in a transporting process thereof and to find VFper se, namely the ratio of an air amount flowing in from an outer circumferential surface of the filter to a drawing amount of the smoker. It is also possible to find the VFon the basis of the given pressure at which the second airtight chamber is supplied with the compressed fluid and the pressure detected by the pressure sensor, which enables a quick inspection. Consequently, the inspection apparatus makes it possible to carry out effective on-machine control on the VFof each filter cigarette, and to reliably control a nicotine and tar amount in the filter cigarette.

According to a specific aspect, the inspection apparatus further has reciprocating means that reciprocates the filter socket assembly toward the filter cigarette in order to receive the filter in the socket removably. In the above-mentioned structure, the cigarette socket assembly includes the pair of seal rings disposed in the socket to be separated from each other in the axial direction and to be reducible in diameters. The seal rings come into tight contact with the filter when reduced in diameters, thereby partitioning the first and second airtight chambers.

In the above-described structure, it is preferable that the seal rings be formed of elastically deformable rubber rings, and that the cigarette socket assembly include compression means that is actuated by operating the reciprocating means as a drive source and compresses each of the rubber rings to reduce the diameters thereof.

With this structure, the first and second airtight chambers can be formed by using one reciprocating means. Furthermore, since the elastically deformable rubber rings are brought into tight contact with the filter part, the compressed fluid and air are prevented from leaking from between the filter part and the seal rings partitioning the first and second airtight chambers. Consequently, a first pressure sensor is capable of detecting the pressure in the first airtight chamber with accuracy when the second airtight chamber is supplied with the compressed fluid of the given pressure. In other words, it is possible to upgrade reliability of control on the VFof filter cigarettes, that is, nicotine and tar, with the simple structure.

As a preferred aspect, the inspection apparatus further has a cigarette socket assembly that is disposed on the other side of the transport path and is allowed to be connected to the filter cigarette when the filter cigarette passes through the inspection position, the cigarette socket assembly including a cigarette socket that is capable of receiving a tip end of the cigarette and defines a third airtight chamber for enclosing the tip end of the cigarette in the inside thereof, and a forward input path for supplying the third airtight chamber of the cigarette socket with a compressed fluid of a given pressure when the second airtight chamber is in a fluidically closed state, the apparatus in which the lateral input path of the filter cigarette assembly is blocked off while the third airtight chamber is supplied with the compressed fluid.

With this structure, it is possible to detect not only the VFof filter cigarettes but also the formation of undesired holes in wrapping paper in the transporting process of the cigarettes on the basis of the pressure detected by the pressure sensor. In this case, since the second airtight chamber is closed, the formation of holes can be detected without fail regardless of the level of VFof the filter cigarettes. As a result, defective filter cigarettes can be surely removed.

As a specific aspect, the inspection apparatus further has a rotatable drum provided with each of the socket assemblies and including an outer circumferential surface defining the transport path.

In order to accomplish the above-mentioned objects, an inspection method for a filter cigarette including a cigarette, a filter that is connected to the cigarette and has a mouthpiece end, and a ventilation area in an outer circumferential surface of the filter for introducing outside air includes the steps of forming a first airtight chamber for enclosing the mouthpiece end of the filter, forming a second airtight chamber for enclosing the outer circumferential surface of the filter including the ventilation area, and measuring a pressure in the first airtight chamber when the second airtight chamber is supplied with a compressed fluid of a given pressure.

According to the inspection method, it is possible to directly find the VFper se, namely the ratio of an air amount flowing in from the outer circumferential surface of the filter to a drawing amount of the smoker. Since the VFis found on the basis of the given pressure at which the compressed fluid is supplied into the second airtight chamber and the pressure detected by the first pressure sensor, the inspection can be quickly carried out.

To be specific, the inspection method is carried out in a process where the filter cigarette is transported in a direction orthogonal to an axial direction thereof.

According to the inspection method, it is possible to quickly inspect each of the filter cigarettes, so that the filter cigarettes can be inspected in the transporting process. Therefore, the inspection method makes it possible to carry out effective on-machine control on the VFof all the filter cigarettes, realizing reliable control on the nicotine and tar amount in the filter cigarettes.

Furthermore, to achieve the above-mentioned object, an inspection method for a filter cigarette having a cigarette, a filter that is connected to the cigarette and has a mouthpiece end, and a ventilation area in an outer circumferential surface of the filter for introducing outside air includes the steps of forming a first airtight chamber for enclosing the mouthpiece end of the filter, forming a second airtight chamber for enclosing the outer circumferential surface of the filter including the ventilation area, forming a third airtight chamber for enclosing a tip end of the cigarette, and measuring a pressure in the first airtight chamber when the third airtight chamber is supplied with a compressed fluid of a given pressure.

To be concrete, the inspection method is carried out in a process where the filter cigarette is transported in a direction orthogonal to an axial direction thereof.

The inspection method makes it possible to detect the formation of undesired holes in the wrapping paper of the filter cigarettes on the basis of the pressure detected by the pressure sensor. Moreover, since the second airtight chamber is closed, it is also possible to detect the formation of the holes without fail regardless of the level of VFof the filter cigarettes.

BEST MODE OF CARRYING OUT THE INVENTION

FIG. 1diagrammatically shows a filter attachment10that attaches a filter to a cigarette. The attachment10has a drum line12that continues from an upstream side toward a downstream side. The drum line12receives a cigarette2and a filter4on the upstream side (right side in the figure), and attaches the filter4to the cigarette2. The drum line12then performs given inspection with respect to an obtained filter cigarette FT, and allows the filter cigarette FT to be removed from the downstream side (left side in the figure). More specifically, the drum line12includes a dilution inspection apparatus18interposed between an end checker drum14and a carrier drum16.

FIG. 2shows both ends of the dilution inspection apparatus18. The filter cigarette FT to be inspected is transferred to the dilution inspection apparatus18at a start point of a rotation angle region θ1from the end checker drum14located immediately upstream thereof. Thereafter, the cigarette FT is transported on an outer circumference of the dilution inspection apparatus18along a rotating direction R through the rotation angle region θ1, a rotation angle region θ2and a rotation angle region θ3, and is transferred to the carrier drum16located immediately downstream at an end point of the rotation angle region θ3.

In the dilution inspection apparatus18, while the filter cigarette is transported through a rotation angle region θ4located in the rotation angel region θ1, filter ventilation VFOf the cigarette FT and undesired holes produced in wrapping paper of the cigarette2of the cigarette FT are inspected in order. Filter cigarettes FT in which defects are found in a result of the inspection are eliminated from the dilution inspection apparatus18in the rotation angle region θ2.

As illustrated inFIG. 3, the filter attachment10is provided with a base frame20and a sub-frame22disposed opposite each other. The inspection apparatus18is disposed between the base frame20and the sub-frame22.

To be more specific, the dilution inspection apparatus18has a drive shaft28, which horizontally extends from the base frame20toward the sub-frame22. One end portion and an intermediate portion of the drive shaft28are rotatably supported by an inner sleeve34through a pair of bearings24. The inner sleeve34horizontally protrudes from a front side of the base frame20in a state where one end thereof is fitted into the base frame20, and at the same time is fixed to the base frame20through a flange48located on the one end side thereof.

One end of the drive shaft28protrudes from the inner sleeve34to a backside of the base frame20, and a drive gear30is fitted to the protruding end through a key32. The drive gear30is connected to a drive source through a gear line, not shown. The drive shaft28can be rotation-driven in the rotating direction R (seeFIG. 2) by receiving a driving force from the drive source. A bush38is fitted on the drive shaft28so as to be located between the bearings24.

The other end of the drive shaft28also protrudes from the inner sleeve34. The other end portion is rotatably supported by the sub-frame22. More specifically, a cylindrical bearing holder36is fitted to the sub-frame22, and the other end portion of the drive shaft28is supported by the bearing holder36through a pair of bearings44. A bush40is fitted with the other end portion of the drive shaft28to be located between the bearings44.

A control sleeve56is fastened onto an outer circumferential surface of the inner sleeve34with a screw. One end of the control sleeve56is airtightly fitted to a suction duct52, and the other end thereof protrudes from the inner sleeve34.

The suction duct52is formed with a cover plate. The cover plate is fixed to a front side of the base frame20and accommodates the flange48of the inner sleeve34. The suction duct52forms a suction path53in consort with the base frame20. The suction path53is connected to a suction device, namely a blower.

There is formed a circumferential groove in the outer circumferential surface of the inner sleeve34. The circumferential groove forms a suction chamber58in between the groove and an inner face of the control sleeve56. The suction chamber58constantly communicates with the suction path53through one end side thereof. In other words, in the outer circumferential surface of the inner sleeve34, there are formed a plurality of communication grooves that cause the suction chamber58and the suction path53to communicate with each other. The communication grooves are arranged at intervals in a circumferential direction of the inner sleeve34. As a consequence, the suction chamber58is constantly supplied with given suction pressure.

A suction groove60is formed in an outer circumferential surface of the control sleeve56. The suction groove60communicate with the suction chamber58through a plurality of radial holes62. To be concrete, the suction groove60is positioned on the other end side of the control sleeve56, and has given width in the axial direction of the control sleeve56. The suction groove60extends in a circumferential direction of the control sleeve56in the rotation angle region θ1and the rotation angle region θ3, excluding the rotation angle region θ2. One end of each of the radial holes62opens in a bottom face of the suction groove60. The radial holes62are arranged at given intervals in the circumferential direction of the control sleeve56. The other end of each of the radial holes62opens in the inner circumferential surface of the control sleeve56.

A drum shell64is rotatably fixed to the other end side of the control sleeve56in a state where the drum shell partially encloses the outer circumferential surface of the control sleeve56. The drum shell64is integrally coupled to the drive shaft28. More specifically, an outer flange66and an inner flange68extend from the drive shaft28and the drum shell64, respectively. The flanges66and68are joined together with connecting screws. Therefore, the drum shell64is rotation-driven integrally with the drive shaft28.

The drum shell64airtightly covers the suction groove60of the control sleeve56. A great number of transport grooves70are formed in an outer circumferential surface of the drum shell64at regular intervals in a circumferential direction thereof. Each of the transport grooves70extends in the axial direction of the drum shell64, and is formed to be shorter than the cigarette2of the filter cigarette FT and to have a semicircular cross section. One end of each of suction holes72opens at a bottom of each of the transport grooves70, and these openings are aligned along the transport grooves70. The suction holes72extend in a radial inward direction of the drum shell64, and the other ends open in an inner circumferential surface of the drum shell64.

Furthermore, axial holes74are formed in the drum shell64correspondingly to the respective transport grooves70. The axial holes74each extend across the suction holes72of the respective transport grooves70and open in an end face of the drum shell64on the inner flange68side.

There is disposed a control ring76outside the inner flange68of the drum shell64, and the end face of the drum shell64is in sliding contact with the control ring76. Accordingly, the opening ends of the axial holes74are covered with the control ring76. The control ring76is supported by a fixed cylinder78using a pin and a coil spring (both not shown) such that the control ring76cannot rotate. The fixed cylinder78is fitted to an outer circumferential surface of the bearing holder36. The coil spring urges the control ring76to press against the end face of the drum shell64. The end face of the drum shell64and the control ring76are in airtight contact with each other.

Formed in an inner end face of the control ring76is a control groove80for elimination. The control groove80stretches over the rotation angle region θ2(seeFIG. 2) so as to have an arc-like shape. A communication hole82extends from a bottom of the control groove80, and opens in an outer end face of the control ring76. Connected to an opening end of the communication hole82is one end of an elimination tube84. The elimination tube84stretches through the fixed cylinder78. Therefore, along with rotation of the drum shell64, the axial holes74are sequentially connected to the elimination tube84through the control groove80. Although not shown, the elimination tube84is connected to a pneumatic source including a compressor and the like through an electromagnetic valve, so that it is possible to supply given elimination pressure through the control groove80to the axial holes74by switching operation of the electromagnetic valve.

Although not shown, in the inner end face of the control ring76, there is formed an atmosphere open groove immediately downstream of the rotation angle region θ3in the rotating direction R of the drum shell64. The atmosphere open groove constantly opens to atmosphere.

When the transport groove70enters the rotation angle region θ1, that is, the suction groove60, along with the rotation of the drum shell64, the suction pressure is supplied from the suction chamber58through the radial holes62and the suction holes72to the transport groove70. As a result, the transport groove70is capable of sucking and receiving the filter cigarette FT from the end checker drum14of the previous step. Thereafter, the filter cigarette FT is transported while being sucked and held by the transport groove70during the period of passing through the rotation angle region θ1and the rotation angle region θ3. During the period in which the filter cigarette FT passes through the rotation angle θ2, the supply of the suction pressure to the transport groove70is stopped. Unless the elimination pressure is supplied, however, the filter cigarette FT continues to be sucked and held by the transport groove70due to remaining pressure, and is transported passing through the rotation angle region θ2.

When the transport groove70further rotates beyond the rotation angle region θ3and is connected to the axial holes74of the transport groove70to the atmosphere open groove of the control ring76, the suction of the filter cigarette FT is cancelled at this point. The released filter cigarette FT is transferred to the carrier drum16of the subsequent step, which is located immediately downstream of the inspection apparatus18, that is, the drum shell64, and continues to be transported.

The drum shell64is attached with a plurality of pairs of assemblies86. Each of the transport grooves70is interposed between one pair of assemblies86in the axial direction thereof. The assemblies86rotate with the drum shell64, that is to say, the respective transport grooves70.

One pair of assemblies86can move toward the filter cigarette FT placed on the transport groove70and away therefrom along with the rotation of the drum shell64. To be concrete, the pair of assemblies86is reciprocating-driven between an actuated position where they advance to the filter cigarette FT side and a rest position where they retreat from the actuated position.

More specifically, when the pair of assemblies86is located at the start end of the rotation angle region θ1shown inFIG. 2, these assemblies86are placed in the rest position.

As to the reciprocating drive of the assemblies86, the rotation angle region θ1is further divided into a rotation angle region θ4located at the center in the rotating direction R, and rotation angle regions θ5and θ6located upstream and downstream of the rotation angle region θ4, respectively, to be adjacent to each other. In other words, the pair of assemblies86is gradually advanced from the rest position toward the actuated position while passing through the rotation angle region θ5, and is held at the actuated position while passing through the rotation angle region θ4. Subsequently, the pair of assemblies86is gradually retreated from the actuated position toward the rest position while passing through the rotation angle region θ6, and is held at the rest position until reaching a start end of the rotation angle region θ5again.

InFIG. 3, the assemblies86are shown simply by chain double-dashed lines. Facing intoFIG. 3, an upper side pair of assemblies86is located in the actuated position, and a lower side pair of assemblies86in the rest position.

Hereinafter, between the assemblies86in pair, the assembly86positioned on the right side of the transport groove70and located in the rest position inFIG. 3will be described with reference toFIG. 4. Although inFIG. 4, the pair of assemblies86located in the rest position is placed on an upper side of the drum shell64differently from the case shown inFIG. 3, this is for the convenience of drawing the figure.

As is apparent fromFIG. 4, the drum shell64has small-diameter portions on both ends of the transport groove70. A support ring88is concentrically fitted on the right small-diameter portion. The support ring88is formed to have a large-diameter step on the transport groove70side, and has an end wall90in contact with the end face of the drum shell64.

Fixed to the end wall90is one end of a guide rod94. The guide rod94extends in the axial direction of the drum shell64. The other end of the guide rod94is fixed to a rotation ring96. The rotation ring96is disposed concentrically with the support ring88on the other end side of the drum shell64.

Two guide pipes100and102are fixed to the rotation ring96. The guide pipes100and102protrude from the front side of the rotation ring96toward the support ring88and stretch parallel to the guide rod94. The guide pipes100and102are arranged in a radial outward direction of the support ring88with a space therebetween in the order named from the guide rod94. In other words, the guide rod94and the guide pipe102are positioned on their respective sides of the guide pipe100in the radial direction. Base ends of the guide pipes100and102are embedded in the rotation ring, and open in a backside of the rotation ring96.

The guide pipe100is positioned coaxially with the transport groove70, that is to say, the filter cigarette FT held by the transport groove70, and has a large diameter end104at a tip end thereof.

A movable sleeve114is slidably fitted on the guide pipe100from the outside. A slider108is attached to an end portion of the movable sleeve114, which is located on the rotation ring96side. The guide rod94pierces the slider108with a slide bearing112interposed therebetween. The slider108is slidably supported by the guide rod94. The slide bearing112is held in the slider108with a snap ring110interposed therebetween. A snap ring122of the movable sleeve114couples the movable sleeve114with the slider108integrally. Accordingly, the slider108is slidably guided by the guide rod94, thereby being able to move toward and away from the drum shell64in the axial direction thereof together with the movable sleeve114. The movable sleeve114coaxially contacts/separates with respect to the transport groove70, or the filter cigarette FT to be inspected, which is held by the transport groove70.

An internal diameter of the movable sleeve114is enlarged in an end portion118on the support ring88side. There is secured a tubular chamber120between the movable sleeve114and the guide pipe100. The tubular chamber120opens toward the large diameter end104side of the guide pipe100. An external diameter of the tubular chamber120is larger than an external diameter of the large diameter end104.

When the assembly86is placed in the actuated position, the movable sleeve114moves closest to the cigarette FT, and the large diameter end104of the guide pipe100enters the tubular chamber120of the movable sleeve114. At this moment, an O-ring106provided to the large diameter end104is in tight contact with an inner end face of the tubular chamber120, and the tubular chamber120is airtightly sealed by the O-ring106.

The end portion118of the movable sleeve114is slidably inserted in a ring-attaching hole126of a ring holder124. The ring-attaching hole126pierces the ring holder124and opens in both end faces thereof. A portion of the guide pipe100located on the large diameter end104side is concentrically disposed in the ring-attaching hole126.

An end plate128is fixed to one end face of the ring holder124, which is located on the drum shell64side. Formed in the end plate128is a slot130located concentrically with the ring-attaching hole126. The slot130has a smaller diameter than the ring-attaching hole126. The ring-attaching hole126and the slot130have respective internal diameters larger than the external diameter of the filter cigarette FT. For this reason, when the assembly86moves from the rest position to the actuated position, the filter-side end portion of the filter cigarette FT is insertable into the ring-attaching hole126through the slot130.

In the ring holder124, a guide hole136is formed parallel with the ring-attaching hole126. The guide hole136has a closed end on one end face side of the ring holder124, and opens in the other end face of the ring holder124, that is, an end face on the rotation ring96side. A guide pipe102is airtightly and slidably inserted into the guide hole136from the opening thereof through an O-ring138.

A radial hole extends from the closed end of the guide hole136toward the ring-attaching hole126. The radial hole opens in an inner circumferential surface of the ring-attaching hole126, and this opening end is located in an intermediate position between the movable sleeve114and the end plate128.

Furthermore, an axial groove140is formed in the inner circumferential surface of the ring-attaching hole126. The axial groove140opens in the other end face of the ring holder124. The axial groove140is attached with a stopper142, and a pin144projects from an outer circumferential surface of the movable sleeve114into the axial groove140. When the assembly86is in the rest position, the pin144is in contact with the stopper142in the axial groove140. Additionally, the pin144works so as to push back the ring holder124through the stopper142when the assembly86moves from the actuated position to the rest position as described below.

Disposed in the ring-attaching hole126is an inner cylinder132. The inner cylinder132is positioned in between the movable sleeve114and the end plate128. The inner cylinder132is brought into slide contact with the inner circumferential surface of the ring-attaching hole126and is movable in the axial direction of the ring-attaching hole126. The inner cylinder132has an internal diameter that is larger than the external diameter of the filter cigarette FT, so that the end portion of the filter cigarette FT can be inserted into the inner cylinder132when the assembly86is moved to the actuated position.

In the inner cylinder132, circumferential grooves are formed in inner and outer circumferential surfaces thereof, and there are also arranged in a circumferential direction thereof a plurality of small holes for causing the circumferential grooves to communicate with each other. The outer circumferential groove communicates with the guide hole136through the radial hole. Therefore, the guide pipe102communicates with the ring-attaching hole126through the outer and inner circumferential grooves and the small holes of the inner cylinder132.

Rubber rings134and135made of silicone rubber are accommodated in the ring-attaching hole126so as to be located on both ends of the inner cylinder132. The rubber ring134is held between the inner cylinder132and the end plate128, and the rubber ring135between the inner cylinder132and the movable sleeve114. Accordingly, the rubber rings134and135are separated away from each other in the axial direction of the ring-attaching hole126. Both the rubber rings134and135are elastically deformable, and they are in a free state when the assembly86is in the rest position. In the free state, internal diameters of the rubber rings134and135are larger than the external diameter of the filter cigarette FT, making it possible to insert the cigarette FT into the rubber rings134and135without contact.

As shown by a chain double-dashed line inFIG. 4, when the ring holder124is placed in the actuated position, the rubber rings134and135are compressed between the end plate128and the inner cylinder132, and between the inner cylinder132and the movable sleeve114, respectively, in the axial direction of the ring-attaching hole126as described below. In this case, since outer circumferences of the rubber rings134and135are restrained by the ring-attaching hole126, internal circumferences of the compressed rubber rings134and135stretch in a radial inward direction to reduce the diameters of the rings. At this moment, if the filter of the filter cigarette FT has passed through the rubber rings134and135and has been inserted in the ring-attaching hole126, inner circumferential surfaces of the rubber rings134and135that are reduced in diameters come into tight contact to the outer circumferential surface of the filter of the filter cigarette FT with no space. At this point, a perforation line6of the filter cigarette FT is positioned between the rubber rings134and135.

In such a state, the inside of the ring-attaching hole126is airtightly sectioned into a surrounding chamber that encircles the outer circumferential surface of the filter in between the rubber rings134and135in the compressed state, and an end chamber located between the rubber ring135and the bottom of the tubular chamber120. The perforation line6of the filter cigarette FT is positioned in the surrounding chamber, and an end portion of the filter4is located in the end chamber (FIG. 6clearly shows the surrounding and end chambers). As is apparent from the foregoing, the surrounding chamber communicates with the guide pipe102, and the end chamber with the guide pipe100.

The inner circumferential surfaces of the elastically deformable rubber rings134and135stretch to be fitted to concaves and convexes of the outer circumferential surface of the filter. Therefore, a satisfactorily sealed state is created between the rubber rings134and135and the filter. Moreover, it is unlikely that the outer circumferential surface of the filter4is overly constricted by the rubber rings134and135to crinkle the outer circumferential surface of the filter4, or tip paper.

A stationary ring146is in tight contact to a back face of the rotation ring96. The stationary ring146is disposed coaxially with the rotation ring96. As illustrated inFIG. 3, the stationary ring146is supported by a ring-shaped support plate148. The support plate148has an inner circumferential portion that is bent and attached to the fixed cylinder78to be fastened to the fixed cylinder78with a bolt. Although not shown, a spring is interposed between the support plate148and the stationary ring146. The spring presses the stationary ring146toward the rotation ring96.

The stationary ring146is formed of an outer ring150and an inner ring152that are superposed upon each other. Opening ends of the guide pipes100and102, which open in the back face of the rotation ring96, are airtightly closed by the inner ring152.

Formed in the inner ring152are slots154,155and156serving as after-mentioned input/output portions of measurement pressure and detection pressure. Among these slots, the slots154and156extend in a prescribed rotation angle region VF in a circumferential direction of the inner ring152in a state where they are detached away from each other in a radial direction of the inner ring152. Referring toFIG. 2, the rotation angle region VF is defined within the rotation angle region θ4.

The slot154is positioned to be able to fit to the opening end of the guide pipe100and has width that is slightly larger than the internal diameter of the guide pipe100. The slot156is positioned to be able to fit to the opening end of the guide pipe102and has width that is slightly larger than the internal diameter of the guide pipe102.

Although as illustrated inFIG. 2, the last slot155is formed on the circumference where the slot154is positioned, the slots154and155are separated away from each other in the circumferential direction of the inner ring152. The slot155extends over a rotation angle region VP, which is defined within the rotation angle region θ4to be located downstream from the slot154.

A plurality of connection holes158are formed in the outer ring150correspondingly to the slots154,155and156. The connection holes158pierce through the outer ring150to communicate with the respective slots154,155and156. Air tubes162are connected to the respective connection holes158through respective nipples160.

The air tube162that communicates with the slot156is connected to a pressure sensor and a pneumatic source. Therefore, when the guide pipe102is connected to the slot156, the pneumatic source can supply the measurement pressure to the surrounding chamber through the air tube162, the guide pipe102, etc., and the pressure sensor monitors the measurement pressure.

Pressure sensors are connected to the respective air tubes162connected to the slots154and155. The pressure sensors measure pressure of the end chamber.

As illustrated inFIG. 4, a roller shaft164projects from the slider108toward the fixed cylinder78. The roller shaft164is fastened to the slider108with a nut166. A roller168serving as a cam follower is rotatably supported by the roller shaft164. The roller168is accommodated in a cam groove170of the fixed cylinder78. The cam groove170is formed in an outer circumferential surface of the fixed cylinder78over the entire circumference thereof. Both sidewalls172and172of the cam groove170guide a rolling motion of the roller168.

In other words, when the assembly86rotates outside the fixed cylinder78along with the rotation of the drum shell64, the roller168moves in the axial direction of the fixed cylinder78, or the guide rod94, along a cam profile of the cam groove170. As a result, the slider108makes a reciprocating motion while being guided by the guide rod94.

Once the slider108is moved toward the drum shell64, the movable sleeve114also moves on the guide pipe100toward the drum shell64. The movable sleeve114then presses the end plate128of the ring holder124through the rubber ring135, the inner cylinder132and the rubber ring134. Consequently, the assembly86, or the ring holder124, advances to the actuated position in which the end plate128comes into contact with the end wall90of the support ring88.

Thereafter, in the state where the ring holder124is in the actuated position, once the slider108is moved toward the rotation ring96together with the movable sleeve114, the pin144of the movable sleeve114pushes back the ring holder124through the stopper142. The ring holder124is thereby returned to the rest position.

Even if the ring holder124makes the reciprocating motion, the ring holder124does not come off from the guide pipe102. Connection between the guide pipe102and the guide hole136of the ring holder124is constantly retained.

FIG. 5shows a cam diagram of the cam groove170. A horizontal axis indicates a rotation angle of the assembly86, and a vertical axis represents a cam lift (namely a reciprocating stroke of the movable sleeve114). As is clear fromFIG. 5, the cam lift is gradually increased from the point when the assembly86passes through the start end of the rotation angle region θ5. The ring holder124accordingly moves toward the actuated position and reaches the actuated position within the rotation angle region θ5.

In the process where the assembly86further rotates and enters the rotation angle region θ4, the movable sleeve114further moves forward. At this point, however, the ring holder124is in the actuated position, and the forward movement of the ring holder124is restricted by the end wall90of the support ring88. Therefore, the forward movement of the movable sleeve114compresses the rubber ring135in between the movable sleeve114and the inner cylinder132, and also compresses the rubber ring134in between the end plate128and the inner cylinder132. As a consequence, the internal diameters of the rubber rings134and135are reduced at this point.

At the same time, the large diameter end104of the guide pipe100enters the tubular chamber120of the movable sleeve114together with the O-ring106, and the pin144of the movable sleeve114and the stopper142of the ring holder124are in the state where they are separated away from each other.

When the assembly86is in the process of passing through the rotation angle region θ4, the cam lift is maintained at a maximum value, and the rubber rings134and135are kept in the state where they are reduced in their diameters.

Subsequently, the assembly86moves from the rotation angle region θ4to enter the rotation angle region θ6. In the process where the assembly86passes through the rotation angle region θ6, the cam lift is gradually reduced. Accordingly, the compression of the rubber rings134and135by using the movable sleeve114is cancelled, which enlarges the internal diameters of the rubber rings134and135to the original state. Once the pin144of the movable sleeve114comes into contact with the stopper142of the ring holder124, the ring holder124moves from the actuated position toward the rest position together with the movable sleeve114.

After the assembly86passes through the rotation angle region θ6, the ring holder124is maintained in the rest position until the assembly86enters the start end of the rotation angle region θ5again.

The assembly86positioned on the left side of the drum shell64, facing intoFIG. 4as viewed, has a similar structure to the assembly86on the right side. Therefore, inFIGS. 2,3and4, members and portions having the same functions are provided with the same reference characters, and explanations thereof will be omitted. Only differences will be described below.

First of all, the cam groove170in combination with the left assembly86is, as is clear fromFIG. 3, formed in an outer circumferential surface of a fixed cylinder174. The fixed cylinder174is fixed onto the outer circumferential surface of the control sleeve56. The support plate148supporting the stationary ring146is fixed to a base frame20.

As illustrated inFIG. 4, the left assembly86is not provided with the guide hole136, the guide pipe102, the slot156and the inner cylinder132.

The left assembly86, or the ring holder124, is provided with the rubber ring134only. The rubber ring134is disposed between the movable sleeve114and the end plate128. When the assembly86is placed in the actuated position, the rubber ring134comes into airtight contact to the end portion of the cigarette2of the filter cigarette FT from the outside. In this case, the reciprocating stroke of the ring holder124, provided by the cam groove170, is set to be virtually half, compared to the ring holder124of the right assembly86.

Accordingly, when the left assembly86is in the actuated position, there is formed an end chamber only. The end portion of the cigarette2of the filter cigarette FT to be inspected is placed in the end chamber.

The slot154of the inner ring152opens to the atmosphere through the holes formed in the outer ring150. Therefore, even if the left assembly86is placed in the actuated position, and the end chamber is formed, pressure of the end chamber is maintained to be atmosphere pressure through the slot154of the rotation angle region VF.

Furthermore, the pneumatic source is connected to the air tube162connected to the slot155of the left assembly86with the pressure sensor. Consequently, as assembly86is passing through the rotation angle region VP in which the slot155is formed, the pneumatic source can supply the measurement pressure to the end chamber, and the measurement pressure is monitored by the pressure sensor.

FIG. 6diagrammatically shows the operation of one pair of assemblies86in the dilution inspection apparatus18.

According to the inspection apparatus18, at the start end of the rotation angle region θ1of the drum shell64, the filter cigarette FT is transferred from the end checker drum14of the previous step into one of the transport grooves70(S100). At this moment, the pair of assemblies86in combination with the above-mentioned transport groove70is in the rest position. The filter cigarette FT is securely received by the transport groove70without interfering with the assemblies86. The tip end of the cigarette2of the filter cigarette FT and the filter4project from both the ends of the transport groove70.

Subsequently, along with the rotation of the drum shell64, the filter cigarette FT is transported while being sucked and held by the transport groove70. Once the filter cigarette FT enters the rotation angle region θ5, the pair of assemblies86gradually moves forward from the rest position toward the actuated position, that is, toward the filter cigarette FT on the transport groove70.

Once the pair of assemblies86is placed in the actuated position (S200), both the end portions of the filter cigarette FT are inserted into the ring-attaching holes126formed in the right and left ring holders124through the slots130of the end plates128.

Thereafter, the rubber rings134and135in the right and left ring holders124each receive a compressive force to be reduced in their diameters, thereby coming into airtight contact onto the outer circumferential surface of the filter cigarette FT. There are formed an end chamber EC and a surrounding chamber SC in the right ring holder124, whereas in the left ring holder124, there is formed an end chamber EC only (S300).

The filter cigarette FT passes through the rotation angle region VF with the pair of assemblies86in the state where the end chambers EC and the surrounding chamber SC are formed. During the period in which the cigarette FT passes through the rotation angle region VF, the guide pipe102of the assembly86located on the filter4side (the right side, facing intoFIG. 6as viewed) is connected to the air tube162. As a result, compressed air is fed into the surrounding chamber SC at a pressure monitored by a pressure sensor P1, which generates measurement pressure (input pressure) in the surrounding chamber SC. The measurement pressure is applied to the outer circumferential surface of the filter4of the filter cigarette FT. Based on the measurement pressure, the compressed air is directed through the perforation line6into the filter4, and then flows into the end chamber EC from the end face of the filter4. Consequently, the pressure that is reduced to be less than the measurement pressure is produced as detection pressure (output pressure) in the end chamber EC.

At this point, the guide pipe100is connected to a pressure sensor P2through the air tube162, so that the detection pressure in the end chamber EC is detected by the pressure sensor P2. Since the rubber rings134and135of the right ring holder124are in airtight contact to the filter4of the filter cigarette FT, the compressed air does not leak out of the surrounding chamber SC and the end chambers EC. Therefore, the pressure sensors P1and P2are capable of detecting with accuracy the measurement pressure and the detection pressure, respectively.

In the rotation angle region VF, the pressure in the end chamber EC of the left ring holder124is maintained to the same level as the atmosphere pressure.

After passing through the rotation angle region VF, the filter cigarette FT enters the rotation angle region VP with the pair of assemblies86. During the period in which the cigarette FT passes through the rotation angle region VP, the guide pipes100of the right and left assemblies86are connected to the respective air tubes162(S400). By so doing, the compressed air is fed into the end chamber EC of the left assembly86, and the measurement pressure in the end chamber EC is applied to the cigarette end of the filter cigarette FT. In the right assembly86, the guide pipe102leading to the surrounding chamber SC is airtightly sealed by the stationary ring146. The guide pipe100leading to the end chamber EC is connected to a pressure sensor P3through the air tube162. The pressure sensor P3detects the detection pressure (output pressure) in the end chamber EC of the right assembly86, which corresponds to the measurement pressure (input pressure) in the end chamber EC of the left assembly86. In other words, when the measurement pressure is applied to the cigarette end, the measurement pressure is transmitted to the filter end of the filter cigarette FT while being reduced. The transmitted pressure appears as the detection pressure.

Again, the rubber rings134and135of the ring holders124are in airtight contact onto the outer circumferential surface of the filter cigarette FT, so that air does not leak out of the surrounding chamber SC and the end chamber EC. This enables the pressure sensor P3to detect the detection pressure with accuracy.

Subsequently, when the filter cigarette FT passes through the rotation angle region VP and enters a rotation angle region θ6, the internal diameters of the rubber rings134and135are enlarged into the original state to be detached away from the outer circumferential surface of the filter cigarette FT in the right and left assemblies86(S500). The assemblies86are moved from the actuated position toward the rest position, and both the end portions of the filter cigarette FT are relatively pulled out of the assemblies86.

After the right and left assemblies86, that is, the ring holders124, are detached away from the filter cigarette FT as described above (S600), if the filter cigarette FT is judged to be defective, it is removed in the rotation angle region θ2. As a consequence, only non-defective cigarettes FT are transported to a dead end of the rotation angle region θ3and transferred from the transport grooves70to the carrier drum16of the subsequent step to be further transported.

FIG. 7diagrammatically shows a measurement principle performed in the rotation angle region VF in the inspection apparatus18. According to this measurement principle, it is possible to find the filter ventilation VF in the filter cigarette FT. The VF is as mentioned the ratio of an air amount flowing in from the perforation line to an amount of smoke drawn by the smoker.FIG. 8shows an analogy model in which the measurement principle is replaced with an electric equivalent circuit. According to the analogy model, when the measurement pressure and the detection pressure measured by the pressure sensors P1and P2are denoted by P1and P2, respectively, the ratio of the detection pressure P2to the measurement pressure P1, that is, P2/P1, is shown by the following equation.

The right side of Equation (1) is identical to a resistance equation (Equation (3)) of the VFin an after-mentioned measurement standard. In other words, the VFis a value found by dividing the detection pressure P2by the measurement pressure P1. It is possible to directly find and monitor the VFby substituting the measurement pressure P1and the detection pressure P2in Equation (1).

Characters in Equation (1) represent the following matters.

RT1: Equivalent resistance of the cigarette end side, which is created when air flows within the cigarette2of the filter cigarette FT.

RT2: Equivalent resistance of the filter side, which is created when air flows within the cigarette2of the filter cigarette FT.

RFF: Equivalent resistance of the cigarette2side, which is created when air flows within the filter4of the filter cigarette FT.

RFR: Equivalent resistance of the filter end side, which is created when air flows within the filter4of the filter cigarette FT.

RP: Equivalent resistance created when air flows from the outside of the cigarette2into the cigarette2through wrapping paper.

RV: Equivalent resistance created when air flows from the outside of the filter4into the filter4through tip paper including the perforation line6.

Therefore, the inspection apparatus18enables effective control of the nicotine and tar of the filter cigarette FT. For example, if a calculating device is connected to the inspection apparatus18, and the measurement pressure P1and the detection pressure P2are inputted to the calculating device to calculate the above-mentioned equation, the VFcan be found immediately. Moreover, if the calculating device is designed to make a judgment as to whether the VFis defective or not, and the electromagnetic valve of the elimination tube84is activated on the basis of the judgment result, it is possible to easily and surely remove the filter cigarettes FT recognized to have defects in the VFthereof.

FIG. 9diagrammatically shows a measurement principle of dilution performed by a conventional inspection apparatus.FIG. 10shows an analogy model thereof, and based on this, the following equation is established according to the ratio between the measurement pressure P1supplied to the cigarette end and the detection pressure P2taken out from the filter end.

The right side of Equation (2) is identical to a resistance equation (Equation (5)) of VTin an after-mentioned measurement standard. This proves that the measurement principle is to find total ventilation VTof the filter cigarette FT. The total ventilation VTis as mentioned above the ratio of the air amount flowing in from the wrapping paper and the perforation line to the amount of smoke drawn by the smoker.

As in the above-mentioned Equation (1), RT1, RT2, RFF, RFR, RPand RVrepresent the equivalent resistance of the cigarette end side and filter end side of the cigarette2, the equivalent resistance of the cigarette side and filter side of the filter4, the equivalent resistance of the wrapping paper and tip paper, respectively.

Although in the cigarette manufacturing industry, the VF, not VT, is generally used as an alternative control target of nicotine and tar, the VFand the VTdo not always have a fixed relationship. It is therefore difficult to accurately estimate the VFon the basis of the VT. For this reason, this conventional method is not capable of estimating (predicting) a correct VF, and is not suitable for control of the nicotine and tar of cigarettes.

FIG. 11diagrammatically shows a measurement standard (which is compliant with ISO) that is commonly used in the cigarette manufacturing industry to measure the VFand the wrapping paper ventilation VP. The measurement using this measurement standard is carried out off-machine with respect to a sampled filter cigarette FT. Characters shown inFIG. 11denote the following matters.

QP: Air amount flowing into the chamber surrounding the cigarette2.

QF: Air amount flowing into the chamber surrounding the filter4.

Q: Air amount flowing out from the filter end face.

According to this method, the air amounts QP, QF, and Q can be measured in a state where negative pressure is supplied to the filter end face of the filter cigarette FT.FIG. 12shows an analogy model of this measuring method. Based on the measured air amounts QP, QF, and Q, resistance equations (Equations (3), (4) and (5)) of VF, VPand VTcan be found.

As in the above-mentioned Equations (1) and (2), RT1, RT2, RFF, RFR, RPand RVrepresent the equivalent resistance of the cigarette end side and filter side of the cigarette2, the equivalent resistance of the cigarette side and filter end side of the filter4, the equivalent resistance of the wrapping paper and tip paper, respectively.

The measuring method of the VFusing the above measurement standard, however, is performed off-machine, and moreover the method measures a flow ratio QF/Q. Therefore, this measuring method requires a long period of time (0.1 second or more) as shown inFIG. 13to gain a stable measurement result in respect of the VF.

By contrast, the inspection apparatus18that measures the pressure ratio P2/P1is capable of finding a highly accurate VFin a short period time (about 5 ms), thereby actualizing the high-speed measurement of the VF. Consequently, the inspection apparatus18having such high-speed response can be applied to the filter attachment10, and is capable of inspecting the VFwith respect to all the filter cigarettes FT manufactured by using the filter attachment. In other words, the apparatus18is capable of performing continuous measurement of the VFon-machine.

FIG. 13shows a measurement result in respect of a filter cigarette FT in which the value of VFis about 60 percent. As to the flow ratio measurement, a flow ratio Q is measured by using a sonic velocity nozzle, and a flow rate QFis measured by a differential pressure method using an orifice of φ1.2.

FIG. 14diagrammatically shows the measurement carried out in the rotation angle region VP in the inspection apparatus18. According to this measurement, the outer circumferential surface of the filter4of the filter cigarette FT is in a closed position due to the surrounding chamber SC, so that the degree of VPcan be judged on the basis of the detection pressure P3in the state where the perforation line of the filter is virtually closed. Accordingly this measuring method is capable of making a reliable judgment as to occurrences of undesired tears and holes in the wrapping paper of the cigarette2even if the VFof the filter cigarette FT is great, that is to say, regardless of the VF.

For example,FIG. 15shows in the form of a histogram a measurement result of the detection pressure P3, which was gained by a conventional measuring method in which the outer circumferential surface of the filter4was not blocked off, and a measurement result of the detection pressure P3, which was gained by the above-described embodiment, with respect to defective filter cigarettes FT in which holes were intentionally made in wrapping paper, and non-defective filter cigarettes FT.

It should be noted, however, that the VFof defective and non-defective filter cigarettes FT was 68 percent. Moreover, the compressed air pressure that was supplied was 1 kPa, and each hole formed in the wrapping paper of the defectives has a diameter of 1 mm.

As is apparent fromFIG. 15, according to the measuring method using the inspection apparatus18, distributions of the detection pressures of the non-defectives and defectives are completely separated, which makes it possible to reliably detect the defectiveness of the filter cigarettes FT. As a consequence, defective filter cigarettes FT are surely removed if the calculating device is further designed to make the defective/non-defective judgment.

In contrast, according to the conventional measuring method, the perforation line6of the filter4is not blocked up, so that the compressed air leaks outside the filter cigarette FT through the perforation line6. As a result, the detection pressure P3is reduced in accordance with the VF. Therefore, in the case of the filter cigarette FT having large VF, the difference of the detection pressure P3between the defectives and the non-defectives is small, and it is difficult to detect defectives by the conventional method.

The present invention is not limited to the above-described one embodiment, and various modifications can be made. For example, as to the dilution inspection apparatus, the step of measuring the VFand that of detecting the defectives attributable to tears and holes in wrapping paper may be carried out in reverse order.

In the one embodiment, the filter cigarette FT is sucked and held in the transport groove70in the rotation angle region θ4. In order to improve accuracy in measuring the VFand accuracy in detecting tears in wrapping paper, however, the suction may be cancelled in the rotation angle region θ4. In other words, it is possible to improve the measurement accuracy, etc. by carrying out the measurement in further faithful accordance with the analogy. To that end, for example, the suction groove60may be discontinued in whole length of the rotation angle region θ4. Again in this case, the filter cigarette FT is securely held on the transport groove70in the rotation angle region θ4not by suction but by the assembly86.

Although the material of the rubber ring is silicone rubber, the material is not particularly limited and may be arbitrarily selected from natural rubber, synthetic rubber, gelatinous materials, etc. It is also possible to enhance the adhesion of the rubber ring with respect to the outer circumferential surface of the cigarette and upgrade the sealing ability by forming a slit in the inner circumferential surface of the rubber ring. Furthermore, in the assembly86on the filter side, the amount of decreasing the diameter of the rubber ring134may be fixed to the same as the rubber ring135by making the rubber ring134softer than the rubber ring135.

The present invention is applied to the filter cigarettes having ventilation areas for directing outside air to the filters. Needless to say, however, the arrangement of the perforation lines as ventilation areas is not particularly limited, and the invention may be applied to various rod-like articles that require the dilution inspection, other than the above-mentioned filter cigarettes. The number of surrounding chambers that surround the outer circumferential surface thereof is not limited to one, and a plurality of surrounding chambers may be arranged along the axial direction thereof. The transport path for rod-like articles may be something other than the drum, and the reciprocation mechanism of the assembly and the compression mechanism of the rubber ring are not limited to those illustrated in the drawings. For example, it is also possible to form two adjacent assemblies integrally in the circumferential direction of the drum shell64and cause the assemblies to reciprocate at the same time.