US3525345A - Tobacco smoke filter - Google Patents

Description

United States Patent [72] Inventor Walter Harris FORElGN PATENTS 1843 Fox Hill Drive. Los Angeles, 14964 8/191 1 Denmark 3 09 California 90025 757.418 10/1933 France 131/209 1 1 pp N9 796,016 559.115 3/1957 Italy 131/105 [22] Filed Feb. 3, 1969 I [45] Patented 25' 1970 Prunary Exammer Samuel Koren Assistant Examiner James H. Czerwonky Attorney-Smyth, Roston and Pavitt [54] TOBACCO SMOKE FILTER 7 Claims, 6 Drawing Figs.

[52] US. Cl 131/261, l3l/l0.5.131/10.7.131/209.131/2l0.13l/212 [5 l] Int. Cl A24d, 1/04, A24fl/ 16 [50] Field of Search 131/ 2618. ABSTRACT; A tobacco smoke filter having overlapping first 2| 310 and second filter elements with an inlet passage and an outlet assa e, res ectivel throu h which the tobacco smoke can [56] References gass. ihe ou zlet of tl 1e inlet gassage is spaced axially and radi- UNITED STATES PA TENTS ally from, and overlaps, the inlet of the outlet passage. The 1,676,142 7/1928 Gunnlaugsson 131/212X inlet passage converges as it extends towards its outlet, and the 3,l25,l00 3/1964 Jany ..l31/26l(B)UX outlet passage diverges as it extends from its inlet. Conduit 3,388.707 6/1968 ..l3 l/26l(B)UX means interconnects the outlet of the inlet passage to the inlet 3,416,541 12/1968 Hoover l3]/26l(B)UX ofthe outlet passage.

W p I M's" 1W1 A Patented Aug. 25, 1970 3,525,345

Irma flag TOBACCO SMOKE FILTER The general object of tobacco filters is the removal of tars and other potentially harmful tobacco smoke components before they reach the smoker. Although there is a plethora of prior art tobacco smoke filters, none of these accomplishes a sufficiently high degree of filtration.

The present invention provides a tobacco smoke filter of simple and inexpensive construction which filters tobacco smoke to a very substantial degree. With the present invention the tobacco smoke is conducted through a long serpentine path which provides numerous opportunities for the harmful smoke components to separate from the main smoke stream and adhere to the filter. The path preferably changes the direction of movement of the smoke a large number of times to cause centrifugal filtration of smoke and to obtain a filtration effect as a result of the impingement of the smoke on numerous wall regions of the filter as the direction of movement of the smoke is changed. A filtration path having long length is desirable to afford a maximum number of opportunities for change of direction and to maximize the filter area into which the smoke is brought into contact.

These concepts may be advantageously embodied in a filter including a first filter element having an inlet passage extending therethrough and a second filter element having an outlet passage extending therethrough. Both of the passages have inlets and outlets with the inlet of the inlet passage being positioned to receive the smoke from the burning mass of tobacco.

To provide a long filtration path having numerous changes of direction, the present invention teaches that the filter passages should overlap so that the inlet of the outlet passage is axially spaced from the outlet of the inlet passage. Thus, the distance between the outlets of the two passages is less than the distance between the inlet and outlet of the outlet passage. Stated differently the outlets of both passages are located in the axial direction on the same side of the inlet of the outlet passage. With this orientation, the smoke upon emerging from the inlet passage, must traverse one reverse bend to become headed toward the inlet of the outlet passage and a second reverse bend to enter such outlet passage. Preferably, the axial spacing is substantial so as to cause the smoke to travel through two full reverse bends.

The outlet of the inlet passage and the inlet of the outlet passage should also preferably be radially spaced. This requires the smoke to travel radially as well as axially in passing between filter passages. In addition, the smoke should be caused to travel circumferentially in moving between the inlet and the outlet passage. This can be accomplished by causing the smoke to travel around the periphery of the first and second filter means in traveling between the inlet and outlet passages.

The inlet passage preferably converges as it extends downstream to thereby increase smoke velocity and the outlet passage preferably diverges as it extends downstream. The passages are preferably formed with baffles or other surface irregularities to impart a swirling motion to the smoke. This increases the length of travel of the smoke and affords greater opportunity for centrifugal and impingement type filtration.

In a preferred form, the filter includes a filter body and the inlet and outlet passages are formed in the filter body. The inlet passage extends from one end face of the filter body through a portion of the lter body and terminates at the periphery of the filter bo' while the outlet passage extends from the periphery of th' filter body through a portion of the filter body and terminates at the other end face of the filter body. The filter body is preferably mounted within a sleeve and the peripheral surface thereof and the sleeve form a chamber or conduit for conducting smoke between the inlet and outlet passages. It is preferred to provide a baffle or other suitable surface adjacent the outlet of the inlet passage against which the smoke emanating from the inlet passage can impinge. Such impingement surface can advantageously be provided by a portion of the peripheral surface of the filter body and/or a portion of the sleeve.

The filter body may be used with a suitable porous filtering media. The porous filter material may be located in the chamber defined by the sleeve and the filter body.

The invention, both as to its organization and method of operation together with further features and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a side elevational view of a cigarette having a filter constructed in accordance with the teachings of this invention incorporated therein;

FIG. 2 is a longitudinal fragmentary sectional view through the filter;

FIG. 3 is a perspective view of the filter body;

FIG. 4 is a sectional view taken along line 44 of FIG. 2 and illustrating the filter body;

FIG. 5 is a fragmentary side elevational view partially in section ofa second embodiment of the invention; and

FIG. 6 is a fragmentary perspective view of the baffle within the passage of the filter body.

Referring to the drawing and in particular to FIG. 1 thereof. reference numeral 11 designates a cigarette having a filter 13 incorporated therein. Except for the filter 13, the cigarette 11 may be of conventional construction and include a sleeve 15 of cigarette paper having a core of tobacco contained therein.

The filter 13 generally includes a filter body 19 encased within a sleeve 21. The filter 13 may be attached to the remainder of the cigarette 11 in any suitable fashion and in the embodiment illustrated, the inner end of the cigarette is received within an extending portion 23 of the sleeve 21. The tobacco 17 may extend all the way to the filter body 21 or may be separated therefrom by a wad of porous filter material 24. Although the filter 13 is illustrated as being a portion of the cigarette 11, it should be understood that the filter may be used in many different ways including, for example, with cigars, cigarette holders, etc.

With reference to FIGS. 2-4, the filter body 19 is preferably integrally constructed of a material which is at least substantially impervious to tobacco smoke, such as a relatively rigid plastic. The filter body 19 may be molded. The filter body 19 includes an inlet filter element 25 and an outlet filter element 27. The filter element 25 has an inlet passage 29 therein extending from an outer end face 31 of the filter body 19 through a portion of the filter body and terminating in an outlet 33 on the periphery of the filter body. The passage 29 has an inlet 34 which faces the tobacco 17 and is adapted to receive smoke therefrom. Surface irregularities in the form of an integral spiral rib or baffle (FIGS. 2 and 6) 35 extend along the surface of the passage 29 with the spiral extending in the direction shown in FIG. 2. The spiral baffle 35 tends to swirl the smoke as the smoke is drawn toward the outlet 33. The spiral baffle has an axial passage 36 through which smoke can pass and preferably has a small lead angle so that the baffle 35 defines an interior spiral groove 37 which also tends to impart a swirling motion to the tobacco smoke as it travels toward the outlet 33. An outer spiral groove 39 is formed on the periphery of the filter element 25 for a purpose described hereinbelow. In the embodiment illustrated, the spiral groove 39 is coextensive with the spiral baffle 35 over a substantial length of the filter element 25.

The filter element 27 has an outlet passage 41 therein which extends from an inlet 43 located on the periphery of the filter body 19 through a portion of the filter body to an outlet 45 located at the opposite end face 47 of the filter body. The filter element 27 has a spiral rib or baffle 49 within the outlet passage 41 defining an inner spiral groove 51 for the purpose of swirling the smoke as it moves toward the outlet 45. The baffle 49 defines an axial passage 52 extending therethrough. An outer spiral groove 53 is formed on the peripheral surface of the filter body 19.

The inlet passage 29 converges as it extends toward the outlet 33 thereof to increase the velocity of the smoke as it extends toward the outlet 33 while the outlet passage 41 diverges as it extends toward the outlet 45 thereof to decrease smoke velocity. The spiral ribs and grooves on the surfaces of the passages 29 and 41 are preferably in a direction tending to move the smoke toward the outlet of the respective passage with a swirling motion.

The shape of the end faces 31 and 47 of the filter body 19 is preferably identical to facilitate the insertion of the filter body 19 into the sleeve 21. The sleeve 21 is preferably a right circular cylinder and the end faces 31 and 47 are preferably circular although other configurations may be used, if desired. The filter body 19 may be retained within the sleeve 21 in any suitable fashion such as with an adhesive.

The filter body 19 has a peripheral surface 55 at least a substantial portion of which lies radially inwardly from the sleeve 21 to define a chamber or conduit 57. As best shown in FIG. 2, the periphery of the filter body 19 generally tapers radially inwardly as it extends axially from the end faces 31 and 47 toward a central region of the filter body. Each of the passages 29 and 41 are of generally conical configuration, however,

these passages are not right circular cones.

The outlet 33 and the inlet 43 are spaced radially. As shown in FIG. 4, the body has a substantial radial dimension so that the peripheral surface 55 forces the smoke to travel circumferentially in traveling between the outlet 33 and the inlet 43. To maximize the length of circumferential travel, the inlet 33 is spaced circumferentially at least 90 and preferably 180 from the inlet 43.

As shown in FIG. 2, the passages 29 and 41 overlap and the outlet 33 is located axially intermediate the inlet 43 and the outlet 45. This requires the smoke to make at least two complete reverse bends in traveling between the outlet 33 and the inlet 43.

In use of the filter, tobacco smoke is drawn into the inlet passage 29 and travels toward the outlet 33 thereof. The rib 35 and the groove 37 impart a spiral or swirling motion to at least some of the smoke as it travels toward the outlet 33 while the progressively reducing cross sectional area of the passage 29 increases the velocity of the smoke. Tars and harmful residues are deposited on the surface of the inlet passage 29. The smoke exits through the outlet 33 and impinges against the portions of the sleeve 21 and of the peripheral surface 55 of the filter element 27 lying downstream thereof. Additional tars and residues are deposited on the peripheral surface 55 and the inner surface of the sleeve 21 as the smoke exiting from the outlet 33 impacts against these surfaces. Once the smoke is in the chamber 57, it travels circumferentially of the filter body 19 to the lower portion of the chamber 57. During this time, tars and residues are deposited on the peripheral surface 55 of the filter body 19 and on the inner surface of the sleeve 21.

Because of the presence of the grooves 39 and 53, some of the smoke in traveling axially and circumferentially toward the inlet 43 will be caused to swirl about the filter body 19 thereby further increasing the length of the filtration path and providing further opportunities for separation of the harmful tobacco smoke components. The smoke enters the inlet 43 of the passage 41 and travels at progressively decreasing velocity due to the increasing cross sectional area of the outlet passage. The baffle 49 and the groove 51 impart a swirling centrifugal motion to the smoke as it progresses toward the outlet 45 and additional residues are deposited on the surface of the outlet passage 41.

In the embodiment of the invention shown in FIG. 5, porous smoke filtering media 59 is positioned within and fills the chamber 570. The embodiment of FIG. is otherwise identical to the embodiment of FIGS. 1-4 and corresponding portions are designated by corresponding reference numbers followed by the letter a. The filtering media 59 can be of any conventional type such as cotton, charcoal, etc. and can be in any conventional form such as fibers or granules.

Although exemplary embodiments of the invention have been shown and described, many changes. modifications and mtl-mfihltinru: man! he made bv one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

I claim:

1. A filter for filtering the smoke from a burnable mass of tobacco comprising:

a filter body having a peripheral surface and first and second end faces. said filter body being constructed of a material which at least substantially prevents the tlow of smoke therethrough;

a sleeve having a passageway therein. said filter body being positioned within said sleeve with at least a portion of the peripheral surface of the filter body being spaced from the sleeve to define a chamber;

said filter body having an inlet passage for conducting smoke away from the tobacco, said inlet passage having an inlet opening at said first end face and positionable to receive the smoke from the tobacco and an outlet spaced from said inlet and opening at the peripheral surface of said filter body. said inlet passage converging as it extends toward the outlet thereof;

said filter body having an outlet passage, said outlet passage having an inlet opening at the peripheral surface of the filter body and an outlet opening at said second end face and spaced from the inlet of said outlet passage, said outlet passage diverging as it extends toward the outlet thereof;

said inlet of said outlet passage being spaced circumferentially along said peripheral surface from said outlet of said inlet passage whereby the smoke must travel circumferentially of the filter body in moving therebetween;

said outlet of said inlet passage and inlet of said outlet passage opening in said chamber whereby said chamber forms a conduit for conducting smoke between the outlet of the inlet passage and the inlet of the outlet passage;

said passages overlapping so that the axial distance between the outlets of the passages is less than the axial distance between the inlet and outlet of the outlet passage; and

said peripheral surface of said filter body defining a baffle in said chamber adjacent the outlet of the inlet passage against which the smoke can impinge.

2. A combination as defined in claim 1 including porous filter material in said chamber.

3. A combination as defined in claim 1 including surface irregularities on said peripheral surface of said filter body for imparting a swirling motion to the smoke in said chamber.

4. A filter as defined in claim 1 including a baffle in one of said passages for imparting a swirling motion to the smoke in said one passage.

5. A filter as defined in claim 1 wherein the cross sectional areas of said end faces are substantially equal to the cross sectional areas of the regions of said passageway which surround said and faces.

6. A filter as defined in claim 5 including circumferentially extending baffles in each of said passages and on said peripheral surface for imparting a circumferential motion to the smoke travelling through said passages and said chamber, each of said passages being generally conical, said peripheral surface closely adjacent the outlet of the inlet passage defining an impingement baffle against which the smoke exiting from the outlet of the inlet passage can impinge.

7. A filter for filtering the smoke from a burnable mass of tobacco comprising:

an inlet filter element and an outlet filter element, each of said filter elements having a generally conical peripheral surface and an end face, said filter elements being constructed of a material which at least substantially prevents the flow of smoke therethrough;

a sleeve having a passageway therein, said filter elements being positioned within said sleeve with at least a portion of the peripheral surfaces of the filter elements being spaced from the sleeve to define a chamber, said filter elements overlapping and with said end faces being remote from each other;

said inlet filter element having an inlet passage for conducting smoke away from the tobacco, said inlet passage having an inlet opening at said end face of said inlet filter element and positionable to receive the smoke from the tobacco and an outlet spaced from said inlet and opening at the peripheral surface of said outlet filter element, said inlet passage converging as it extends toward the outlet thereof;

said outlet filter element having an outlet passage, said outlet passage having an inlet opening at the peripheral surface of the inlet filter element and an outlet opening at said end face of the outlet filter element and spaced from the inlet of said outlet passage, said outlet passage diverging as it extends toward the outlet thereof;

said inlet of said outlet passage being spaced radially from said outlet of said inlet passage whereby the smoke must travel radially of the sleeve in moving therebetween;

said outlet of said inlet passage and inlet of said outlet passage opening in said chamber whereby said chamber forms a conduit for conducting smoke between the outlet of the inlet passage and the inlet of the outlet passage;

said passages overlapping so that the axial distance between the outlets of the passages is less than the axial distance between the inlet and outlet of the outlet passage; and

said peripheral surface of said outlet filter element defining a baffle in said chamber adjacent the outlet of the inlet passage against which the smoke can impinge.

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