referring initially to fig1 , there is shown an e - cigarette 10 embodying the present invention , namely , a safety mouthpiece 20 slideably and rotatably mounted to the end of the e - cigarette opposite the tip end 12 . the tip of e - cigarette 10 may include an led 14 to simulate the act of smoking . the e - cigarette 10 includes a tubular body 16 , typically housing a battery , and a control circuit including a sensor for determining when the vaporizing element should be activated based upon an individual drawing on the mouthpiece 20 when in an open position to activate the e - cigarette . as schematically illustrated in fig3 , tubular body 16 of the e - cigarette houses a source 18 of volatizable material , such as propylene glycol , which may include nicotine , flavorants , or other substance desired to be used in connection with the e - cigarette . an axially extending chamber 19 receives the material to be volatized and includes a heater ( not shown ) or other conventional device , which is selectively coupled to a battery ( not shown ) for powering the e - cigarette when a pressure drop is detected by a sensor contained within the tubular body 16 of the cigarette . all e - cigarettes have similar internal components for vaporizing or atomizing the source 18 of volatizable material . these components form no part of the present invention other than to provide a tubular housing to which the mouthpiece 20 is mounted . one such e - cigarette is described in pct publication no . wo 2014 / 110119 , filed jan . 8 , 2014 , and entitled electronic cigarette , the disclosure of which is incorporated herein by reference . tubular body 16 defining the body of the e - cigarette 10 is typically made of metal or plastic material to which there is slideably mounted the safety mouthpiece 20 of the present invention . the mouthpiece 20 includes an outer sleeve 22 , which is relatively thin and typically made of stainless steel or other metal . it is slideably mounted to the tubular body 16 by a polymeric collar 24 fixedly secured within one end 23 of sleeve 22 but having an internal diameter slightly greater than the outer diameter of tubular body 16 . the sleeve surrounds a stationary locking insert 26 ( fig3 ) which is fixedly mounted to the end 15 of tubular body 16 , such as by press - fitting , a bonding material , ultra - sonic welding , or the like depending upon the materials used . insert 26 has flange 27 which overlies the cylindrical end of tubular body 16 and has a smaller outer diameter then the inner diameter of sleeve 22 to allow the mouthpiece 20 to move with respect to the e - cigarette body 16 . the insert 26 also has a cylindrical projection 29 which extends into tubular body 16 of the e - cigarette , as seen in fig2 . projection 29 assists in the fixed mounting of insert 26 to end 15 of tubular body 16 . air flow through the e - cigarette 10 must be isolated and directed axially through the body of the e - cigarette to travel past the vaporizing section 19 and entrain the vaporized nicotine solution . effective air seals are necessary in key mating surfaces of the sliding mouthpiece sleeve 22 to prevent undesired air ingress into the mouthpiece assembly during draw ( puffing ) by the user . the sliding mouthpiece sleeve 22 shown in fig1 must create and maintain an adequate seal to prevent air ingress between the inside circumferential surfaces of collar 24 and the outside surface of tubular body 16 . in addition , an adequate seal must be created and maintained between the outside circumferential surface of the flange on insert member 26 and the inside surface of sliding mouthpiece sleeve 22 . these seals can be accomplished by employing suitable sealing rings or , in the case of insert 26 , by bonding the fixed insert to the inner cylindrical surface of sleeve 22 . insert 26 has an axial port 28 which includes a conical opening defining a valve seat 30 . insert 26 also includes axially and radially extending arcuate locking tabs 32 ( best seen in fig1 and 14 ) which interlock with mating locking tabs 42 of a sealing member 40 , which is fixedly mounted to the end 21 of sleeve 22 . these pairs of angularly and axially spaced locking tabs 32 , 42 define a bayonet - type lock for securing the mouthpiece 20 to the e - cigarette tubular body 16 . sealing member 40 includes an axially extending plunger 44 with a conical end 46 that , together with the valve seat 30 of insert 26 , form a valve which opens and closes the flow path ( arrow a ) of vapor through port 28 as the mouthpiece moves to the left or right , respectively , as seen in fig3 and 11 , between open and closed positions . the axially extending arcuate interlocking tabs 42 of the sealing member 40 interlock with tabs 32 of the insert 26 when in a locked position shown in fig2 - 5 . when sleeve 22 is rotated in a counterclockwise direction to an unlocked position as illustrated in fig6 - 11 , the mouthpiece 20 can be manually pulled and moved to the left in these figures against the force of a tension spring 50 , which tends to urge the sealing member 40 into a sealing position as illustrated in fig3 . for such purpose , spring 50 has one end 52 secured to a tab 34 on insert 26 near end 15 of tubular body 16 and an opposite end 54 secured to a tab 25 on collar 24 . the tab 34 ( fig2 , 4 , 6 , 8 , 10 , and 13 ) on insert 26 is used to fixedly anchor end 52 of spring 50 to insert 26 while a similar tab 25 ( fig2 , 4 , 6 , 8 , 10 , and 13 ) on collar 24 anchors the opposite end of spring 50 to sliding collar 24 . the spring 50 is in tension to urge the sealing member 40 at the end of mouthpiece 20 into sealing engagement with the insert member 26 . in the valve closed and locked position as illustrated in fig2 and 3 , the flow path of vapor ( normally in the direction indicated by arrow a in fig3 ) is prevented , and the e - cigarette 10 cannot be used . to unlock the mouthpiece to allow use of the e - cigarette 10 , it is necessary to rotate the sleeve 22 in a counterclockwise direction , as illustrated in fig8 - 11 , in which the interlocking bayonet tabs 32 and 42 clear one another and allow the user to pull the sleeve 22 and mouthpiece 20 rearwardly in the direction indicated by arrow b in fig8 - 11 . this opens the port 28 until it reaches a fully open position as shown in fig1 . in this position , the mouthpiece must be held in an open position against the tension of spring 50 , typically by the user placing their fingers adjacent the collar 24 around tubular body 16 in an area indicated by arrow c in fig8 - 11 to prevent the spring 50 from returning the conical end 46 of plunger 44 to a sealed position with respect to valve seat 30 . thus , to use the electronic cigarette , it is necessary for the user to both rotate the mouthpiece 20 in a counterclockwise direction approximately 90 ° and draw the sleeve mouthpiece rearwardly the distance of approximately ¼ inch against the tension of spring 50 to open the vapor flow path from vaporizer chamber 19 into the end area 17 ( fig9 and 11 ) of tubular body 16 , which is in communication with the port 28 of insert 26 . the end of sealing member 40 includes a pair of arcuate exit apertures 48 ′ which align with the open spaces between the now spaced - apart locking tabs 32 , 42 when the mouthpiece is in an open position , as seen in fig1 - 12 , to provide a flow path from vaporizing chamber 19 to the exit apertures 48 at &# 39 ; the end of mouthpiece 20 . as long as the sleeve 22 is held in an open position , repeated puffs can be made of the electronic cigarette . once released ; sealing member 40 will , under the tension of spring 50 , move to a sealed position , as illustrated in fig6 and 7 , whereupon the user can then rotate the sleeve 22 clockwise , such that tabs 32 and 42 interlock , as illustrated in fig2 - 3 , to prevent axial movement of the mouthpiece 20 to an open use position . an alternative embodiment of the invention is illustrated in fig1 and 15 . in this embodiment , the spring 50 is deleted , such that the user need not hold the sleeve 22 in an open position with their fingers once in an unlocked position . the sliding friction between the collar 24 and the outer circumferential surface of tubular body 16 is selected such that the mouthpiece can be relatively easily slid along the e - cigarette but , in the embodiment shown in fig1 and 15 , remains in an open usable position for use of the cigarette . in the embodiments with the spring , the collar 24 is in loose frictional engagement with tubular body 16 , allowing the spring to move the sealing member 40 against the insert 26 for closing the valve defined by the interface between the sealing plunger 46 and valve seat 30 under the tension of spring 50 . the spring constant is selected to provide the desired closure of the mouthpiece without requiring an excessive effort on the part of the user to maintain it open during use . the materials of the sealing member 40 , insert 26 , and collar 24 typically will be a polymeric material suitable for use with e - cigarettes . such material may include a high density polymer , such as polyethylene or polyacetate . the spring 50 typically will be made of stainless steel , as will the outer sleeve 22 of mouthpiece 20 . the length of mouthpiece 20 is approximately ¾ inch , while the diameter is only slightly more than the diameter of tubular body 16 of the e - cigarette 10 and dimensionally simulates a filter on the end of a normal cigarette . it will become apparent to those skilled in the art that various modifications to the preferred embodiments of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims .
a safety mouthpiece which can be placed over the exit end of an electronic cigarette effectively blocks the flow path of vapor through the cigarette until the mouthpiece is moved with respect to the e - cigarette in a manner to open a valve . with the valve opened in the mouthpiece , the e - cigarette is allowed to function , and the user can draw vaporized material through the safety mouthpiece .