Abstract:
An valve assembly is provided that automatically dispenses aerosol content from a can at predetermined intervals. A diaphragm at least partially defines an accumulation chamber that receives aerosol content from the can during an accumulation phase. Once the internal pressure of the accumulation chamber reaches a predetermined threshold, the diaphragm flexes to initiate a spray phase, during which the aerosol content is delivered from the accumulation chamber to the ambient environment. A rotatable pawl provides resistive pressure and control of diaphragm movement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to aerosol dispensing devices, and in particular to valve assemblies that provide automatic dispensing of aerosol content at predetermined time intervals, without requiring the use of electrical power. 
     Aerosol cans dispense a variety of ingredients. Typically, an active is mixed with a propellant which may be gaseous, liquid or a mixture of both (e.g. a propane/butane mix; carbon dioxide), and the mixture is stored under pressure in the aerosol can. The active mixture is then sprayed by pushing down/sideways on an activator button at the top of the can that controls a release valve. For purposes of this application, the term “chemical” is used to mean liquid, liquid/gas, and/or gas content of the container (regardless of whether in emulsion state, single phase, or multiple phase). 
     The pressure on the button is typically supplied by finger pressure. However, for fragrances, deodorizers, insecticides, and certain other actives which are sprayed directly into the air, it is sometimes desirable to periodically refresh the concentration of active in the air. While this can be done manually, there are situations where this is inconvenient. For example, when an insect repellant is being sprayed to protect a room overnight (instead of using a burnable mosquito coil), the consumer will not want to wake up in the middle of the night just to manually spray more repellant. 
     There are a number of prior art systems for automatically distributing actives into the air at intermittent times. Most of these rely in some way on electrical power to activate or control the dispensing. Where electric power is required, the cost of the dispenser can be unnecessarily increased. Moreover, for some applications power requirements are so high that battery power is impractical. Where that is the case, the device can only be used where linkage to conventional power sources is possible. 
     Other systems discharge active intermittently and automatically from an aerosol can, without using electrical power. For example, U.S. Pat. No. 4,077,542 relies on a biased diaphragm to control bursts of aerosol gas at periodic intervals. See also U.S. Pat. Nos. 3,477,613 and 3,658,209. However, biased diaphragm systems have suffered from reliability problems (e.g. clogging, leakage, uneven delivery). Moreover, they sometimes do not securely attach to the aerosol can. 
     Moreover, the cost of some prior intermittent spray control systems makes it impractical to provide them as single use/throw away products. For some applications, consumers may prefer a completely disposable product. 
     Thus, a need still exists for improved, inexpensive automated aerosol dispensers that do not require electrical power. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect the invention provides a valve assembly that is suitable to dispense a chemical from an aerosol container. It can automatically iterate between an accumulation phase where the chemical is received from the container, and a spray phase where the received chemical is automatically dispensed at intervals. 
     There is a housing mountable on an aerosol container, a movable diaphragm associated with the housing which is linked to a sloped track, the diaphragm being biased towards a first configuration, and an accumulation chamber inside the housing for providing variable pressure against the diaphragm. There is also a first passageway in the housing suitable for linking an interior portion of the aerosol container with the accumulation chamber. 
     A second passageway in the housing is suitable for linking the accumulation chamber with an outlet of the valve assembly, and a valve stem is positioned in the housing which the sloped track can ride along. A pawl is rotatably positioned on the sloped track to ride on the sloped track. When the diaphragm is in the first configuration the valve assembly can prevent spray of the chemical out of the valve assembly and permit chemical to flow from the aerosol container into the accumulation chamber via the first passageway. When the pressure of chemical inside the accumulation chamber exceeds a specified threshold the diaphragm can move from the first configuration to a second configuration wherein spray is permitted to exit the valve assembly. 
     In preferred forms a portion of the diaphragm blocks off the first passageway when the diaphragm is in the second configuration, a portion of the sloped track restricts flow to the second passageway when the diaphragm is in the first configuration. A pawl can be linked to a rotor, the rotor having an upper surface that can be at least partially coated with putty. The sloped track preferably is helically sloped. The pawl rides on it to resist movement of the diaphragm from the first configuration to the second configuration. Pressure supplied by the diaphragm towards the pawl can cause the pawl to rotate, thereby permitting movement of the diaphragm towards the second configuration. 
     A toe of the pawl will flare radially outwardly off of the track when the diaphragm approaches the second configuration. Also, the diaphragm has a radially outward section, a radially inward section, and an orifice there between. In another aspect, the accumulation chamber has a base that is sloped so as to direct liquid chemical that may collect in the accumulation chamber towards the first passageway. 
     If desired, a spring can be disposed in the housing to resist axial movement of the diaphragm from the first to the second configuration. Also, a porous barrier can be disposed within the housing between the aerosol container and the first passageway. These changes will slow the interval between bursts. 
     In another aspect, methods are provided for using these valve assemblies with aerosol containers are also disclosed. 
     The present invention achieves a secure mounting of a valve assembly on an aerosol can, yet provides an actuator that has two modes. In one mode the valve assembly is operationally disconnected from the actuator valve of the aerosol container (a mode suitable for shipment or long-term storage). Another mode operationally links the valve assembly to the aerosol container interior, and begins the cycle of periodic and automatic dispensing of chemical there from. Importantly, periodic operation is achieved without requiring the use of electrical power to motivate or control the valve. 
     The valve assembly has few parts, and is inexpensive to manufacture and assemble. Further, it does not require the use of small orifices which might be susceptible to clogging, and it is otherwise relatively self-cleaning to help avoid clogs and/or inconsistent bursts. For example, the movement of the pawl along the sloped track avoids residue accumulation along the track. 
    
    
     The foregoing and other advantages of the invention will appear from the following description. In the description reference is made to the accompanying drawings which form a part thereof, and in which there is shown by way of illustration, and not limitation, preferred embodiments of the invention. Such embodiments do not necessarily represent the full scope of the invention, and reference must therefore be made to the claims herein for interpreting the scope of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of an automatic dispensing valve of the present invention in an “off” configuration, mounted onto an aerosol can; 
     FIG. 2 is a view similar to FIG. 1, but with the valve in an “on” position; 
     FIG. 3 is an enlarged sectional view taken along line  3 — 3 , during an accumulation portion of the dispensing cycle; 
     FIG. 4 is a view similar to FIG. 3, but with the accumulation chamber in a partially pressurized state; 
     FIG. 5 is a view similar to FIG. 4, but with the valve in a spray configuration; 
     FIG. 6 is a view similar to FIG. 3, but of a second embodiment that includes a porous barrier; 
     FIG. 7 is a view similar to FIG. 3, but of a third embodiment that includes a spring; 
     FIG. 8 is a view similar to FIG. 2, but of a fourth embodiment that includes an accumulation chamber with a sloped lower wall; and 
     FIG. 9 is a view similar to the top portion of FIG. 8, but with the valve in a spray configuration. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIG. 1, an aerosol can  22  includes a cylindrical can wall  21  that is closed at its upper margin by the usual dome  23 . The joint between the upper margin of the can wall  21  and the dome  23  is the can chime  31 . An upwardly open cup  27  is located at the center of the dome  23  and is joined to the dome by rim  29 . 
     A conventional valve  33  is located at the center of the valve cup  27 . The valve  33  has an upwardly extending valve stem  25 , through which the aerosol contents of the can may be expelled. Valve  33  is shown as a vertically actuated valve, which can be opened by moving the valve stem  25  directly downwardly. Instead, one could use a side-tilt valve where the valve is actuated by tipping the valve stem laterally and somewhat downwardly. 
     An automatic aerosol dispenser (generally  20 ) in accordance with the invention is configured for engagement with the vertically actuated type valve  33 . The dispenser is mostly polypropylene, albeit other suitable materials can be used. 
     The dispenser  20  has a mounting assembly  26  including an axially extending inner wall  28  and peripheral skirt  30  that are joined at their axial outer ends. It should be appreciated that throughout this description, the terms “axially outer, axially downstream, axially inner, axially upstream” are used with reference to the longitudinal axis of the container. The term “radial” refers to a direction outward or inward from that axis. 
     The inner wall  28  and skirt  30  engage the valve cup rim  29  and can chime  31 , respectively. In particular, inner wall  28  has a radially inwardly extending flange  35  that is configured to snap-fit over the rim  29 , while skirt  30  engages the inner surface of chime  31 . In operation, the dispenser  20  is can be forced downwardly onto the chime  18  and rim  29 , thus fastening the dispenser  20  to the aerosol can  22 . The dispenser  20  can be actuated to activate the flow of aerosol content from the can  22  to the dispenser, as will now be described. 
     In particular, an inner wall  28  is threaded on its radially inner surface to receive a valve assembly  32  that is rotatable therein. The valve assembly  32  includes an axially extending annular wall  38  that is threaded on its outer surface to engage the threads of inner wall  28 . The threads have a predetermined pitch such that, as the valve assembly  32  is rotated clockwise with respect to the assembly  26 , it is displaced axially along the direction of arrow A with respect to aerosol can  22 , as illustrated in FIG.  2 . This initiates an accumulation cycle. A stop  37  engages the rim  29  to limit the amount of permitted axial displacement of the dispenser relative to the can. 
     Valve assembly  32  further includes an annular wall  40  disposed radially inwardly of wall  38  that defines therein an axially extending cylindrical pathway portion  42 . When the dispenser  20  is initially mounted onto aerosol can  22 , the axially inner edge of wall  40  is disposed adjacent, and aligned with, the valve stem  25 . However, it is not pressing down on stem  25 . 
     Because the valve stem is not activated in this position, the valve assembly  32  has not yet engaged the aerosol can  22 , and the assembly is in a storage/shipment position. However, as the valve assembly  32  is rotated to displace the dispenser  20  along the direction of arrow A, wall  40  depresses the valve stem  25 , thereby engaging the valve assembly  32  with the aerosol can  22  and allowing the aerosol content to flow from the can into the valve assembly  32 . 
     Valve assembly  32  further includes an annular wall  47  that extends axially downstream from wall  38 , and is displaced slightly radially inwardly with respect thereto. An outer annular sealing wall  44  extends axially upstream and radially outwardly from the axially outermost edge of wall  47 . The outer surface of axially inner portion of wall  44  engages the inner surface of a flange on skirt  30 , and is rotatable with respect thereto to provide a seal between the mounting assembly  26  and valve assembly  32 . Wall  44  is also easily engageable by a user to rotate the mounting assembly  26 , as described above. 
     Walls  38  and  40  are connected at their axially outer ends by an annular, radially extending wall  50 . An annular axial wall  46  extends downstream from wall  50 , and defines at its axially outer edge a seat for an annular radially extending cover  49 , which is further supported by wall  47 . In particular, cover  49  has an axially inwardly extending flange  51  disposed proximal its radially outer edge that engages the inner surface of wall  47 . Wall  47  defines an internal void  36 , which is occupied by the valve assembly  32 , as is further illustrated with reference now also to FIG.  3 . Cover  49  is annular to define a centrally disposed opening that serves as an outlet  64  for aerosol content, as will become more apparent from the description below. 
     As is best seen in FIGS. 3 and 4, valve assembly  32  has an annular base which is defined by that portion of annular wall  50  that extends radially inwardly of flange  52 . Walls  50  and  40  are integrally connected to an annular axially extending wall  54  that is substantially aligned with wall  40 . Walls  40  and  54 , in combination, define the above-described conduit  42  that extends from the valve stem  25  and into valve assembly  32 . 
     A first channel is defined by a slot  56  that extends radially through wall  54  from channel  42  to provide an inlet to an accumulation chamber  71 . A radially extending wall  62  is disposed at the axially outer end of wall  54  and terminates channel  42 , thereby forcing all aerosol content flowing through conduit  42  into the accumulation chamber  71  during the accumulation cycle. 
     An annular neck  60  extends axially inwardly from the radially inner edge of cover  49 , and is axially aligned with wall  54 . Neck  60  terminates slightly axially downstream of wall  62  such that a second channel defined by a slot  63  extends radially between walls  62  and  60 , and downstream of channel  56 . Neck  60  is in fluid communication with channel  63 , and defines a nozzle that terminates in an axially extending outlet  64  of dispenser  20  at its axially outer end. Channel  63  is in fluid communication with the accumulation chamber  71  to deliver stored aerosol content to the outlet  64  as a spray during a spray cycle that follows each accumulation cycle, as will be described in more detail below. 
     With continuing reference to FIG. 3, annular wall  54  has a stepped outer diameter that provides a seat for a retainer wall  66 , which is frustoconical and has a helically sloped track  68  disposed on its outer surface. An annular rotor  76  is disposed axially upstream from, and adjacent, wall  49 , and extends radially inwardly from the radially inner surface of wall  46 . A highly viscous gel or other material, such as silicone putty, is disposed between wall  46  and rotor  76 , and also between wall  49  and the rotor. The putty controls the rotation response of rotor  76  for any level of diaphragm force, and to a minor extent inhibits downward movement of the rotor. A flexible pawl  78  extends radially inwardly, and engages the sloped track  68  during the accumulation cycle. 
     The axially inner surface of retainer  66  is attached to one end of a flexible, monostable diaphragm  70  that extends substantially radially between walls  52  and  66 . Diaphragm  70  has a radially outer end that is seated in a gap between walls  46  and  52 , and has a radially inner end that is engaged with the inner surface of retainer  66 . Diaphragm  70  is normally biased towards a stable closed position, as illustrated in FIGS. 1-3. The pressure generated within the accumulation chamber  71  during accumulation cycles forces the diaphragm from the stable position towards a second, unstable position, illustrated in FIG.  5 . Once the diaphragm is in the position illustrated in FIG. 5, the spray cycle is initiated. FIG. 4 illustrates the diaphragm in an unstable state during the transition from the accumulation cycle to the spray cycle. 
     Diaphragm  70  is substantially bow-shaped, and has a convex outer surface that touches wall  50  closed such that accumulation chamber  71  has an axially extending section  72  and a radially extending section  74 . Axially extending section  72  is defined by the radially inner surfaces of retainer  66  and diaphragm  70 , radially outer surface of wall  54 , and axially outer surface of wall  50 . Radially extending section  74  is defined by axially inner surface of diaphragm  70 , axially outer surface of wall  50 , and radially inner surface of flange  52 . An orifice  75  extends axially through the diaphragm  70  so as to provide fluid communication between sections  72  and  74  during the accumulation and spray cycles. A pair of notches  73  is disposed in the convex surface to assist in the transition of diaphragm between its closed and open positions, as will be described in more detail below. 
     Still referring to FIG. 3, during operation the valve assembly  32  is rotated to initiate the accumulation cycle, and aerosol content flows through conduit  42  along the direction of arrow B. The aerosol content is then forced to travel through channel  56  and into the accumulation chamber  71 . Because the radially inner surface of retainer member  66  provides a barrier to channel  63 , the aerosol content stored within accumulation chamber  71  is unable to exit through channel  63 . As shown in FIG. 7, the inner surface can be cupped, if desired. Aerosol content is thus forced to build up within axially extending section  72  of accumulation chamber  71 . As pressure accumulates within section  72 , retainer member  66  begins to become displaced axially downstream. 
     Referring now to FIG. 4, the radially inner portion of diaphragm  70  also becomes axially displaced due to pressure within axial section  72 . This removes the diaphragm  70  from contact with wall  50 , and allows the aerosol content occupying axial section  72  to travel into radial section  74  along the direction of arrow D via orifice  75  as additional aerosol content enters channel  56  from can  22 . As aerosol content continues to accumulate in the chamber  71 , the pressure continuously biases diaphragm  70  and retainer  66  axially outwardly. 
     As the diaphragm  70  and retainer  66  become displaced, pawl  78  is urged to rotate under forces provided via the engagement with the sloped track  68 . Accordingly, pawl  78  translates its rotational motion to the rotor  76 , which rotates under resistance from the viscous gel. Rotor  76  is thereby continuously rotated under forces provided by the engagement of the pawl  78  with the sloped track  68 . 
     Referring now to FIG. 5, once the pressure within accumulation chamber  71  reaches a predetermined threshold, the diaphragm  70  and retainer wall  66  become biased sufficiently axially outwardly so as to terminate the accumulation cycle, and begin the spray cycle. In particular, as the retainer  66  is biased towards its fully axially outward position, the seal between channel  63  and retainer is removed. The aerosol contents stored under pressure within the accumulation chamber  71  then burst along the direction of arrow E from chamber  71 , through channel  63 , and out the dispenser  20  at the outlet  64 . 
     As the seal between the retainer  66  and channel  63  is removed, the pawl  78  becomes biased sufficiently radially outwardly so as to slide off the sloped track  68 , thereby removing most of the resistance to the axial displacement of the diaphragm. This allows a quick blast of aerosol content out the dispenser  20 . It should be apparent to one having ordinary skill in the art that the pressure threshold within accumulation chamber  71  is at least partially dependent on the viscosity of the gel as well as the spring coefficient of diaphragm  70 . 
     Diaphragm  70  further includes an annular hub  77  disposed radially inwardly with respect to orifice  75 . Hub  77  has an inner diameter approximately equal to the outer diameter of wall  54  so as to slide therealong during operation. Once the pressure within accumulation chamber  71  has reached the predetermined threshold, and the diaphragm is biased to its full axially outer position, hub  77  becomes radially aligned with, and provides blockage to, channel  56 . Again, a cupped contacting surface (not shown) could alternatively be provided. As a result, leakage is minimized between the conduit  42  and accumulation chamber  71  during the spray cycle. Because aerosol content is thus prevented from flowing freely from the can  22  into the accumulation chamber  71  during this portion of the cycle, the output spray is substantially limited to the aerosol content that was stored in the accumulation chamber  71  during the previous accumulation cycle. 
     Once the pressure within the chamber has abated so as to be below a predetermined threshold, the internal spring force of diaphragm  70  biases the diaphragm and retainer  66  axially inwardly to the closed position illustrated and described above with reference to FIG.  3 . The seal between hub  75  and channel  56  is thus removed, and the seal between retainer  66  and channel  63  is re-established. Additionally, pawl  78  re-engages the sloped track  68 . Accordingly, as described above, aerosol content flows from the can  22  and into the accumulation chamber  71  to begin a new accumulation cycle. 
     Thus, aerosol content may be emitted at predetermined time intervals without the need for any electrical power. As a result, the can  22  and dispenser  20  are fully portable, and may be used wherever the efflux of aerosol content is desired. Moreover, the dispenser may be disengaged and re-engaged with the can  22  by rotating wall  44  counter-clockwise and clockwise, respectively, as described above. 
     Many modifications may be made to the first illustrated embodiment without departing from the present invention. For example, the diaphragm  70  may be designed to be stable at a point where it does not touch wall  50 . During the accumulation cycle, the aerosol content would accumulate directly within both the axial and radial sections the chamber  71  without the need to initially lift the diaphragm  70 . 
     Furthermore, as illustrated in FIG. 6, the flow of aerosol content from the can  22  to the chamber  71  may be further controlled using a flow regulator, such as a porous gasket  80 . Where gasket  80  is disposed in conduit  42 , any aerosol content flowing from can  22  into the chamber  71  must pass through it, and thereby be slowed. Gasket  80  is preferably made of an open-celled foam or any other similarly permeable material. The installation of gasket  80  thus limits the flow rate of aerosol content from the can  22  to correspondingly prolong the accumulation cycle and decrease the frequency of sprays during operation. 
     As illustrated in FIG. 7, the frequency of iterations between the accumulation cycle and spray cycle can be further controlled using a spring  82 . In particular, dispenser  20  could be constructed to further include a coil spring  82  that extends around neck  60 , and between the axially inner surface of cover  49  and axially outer surface of retainer  66 . Accordingly, the spring force biases the retainer  66  radially inwardly, and resists the axially outward displacement of retainer  66  in response to pressure within the accumulation chamber  71 . The pressure threshold within the chamber  71  to initiate the spray cycle is thereby increased, thereby also increasing the amount of time during accumulation cycles. 
     Another alternate embodiment is illustrated in FIGS. 8 and 9, in which reference numerals corresponding to like elements of the previous embodiment are incremented by 100 for the sake of clarity and convenience. In particular, dispenser  120  is configured to be mounted onto an aerosol can  122  that terminates at its radial end with a valve cup rim  129  rather than the chime described above. Accordingly, the mounting assembly includes a threaded wall  128  having a radially inwardly extending flange  135  that engages the valve cup rim to securely mount the dispenser  120  onto the can  122 . Threaded wall  128  receives correspondingly threaded wall  138  such that a user rotates wall  144  to actuate the dispenser  120 . 
     Dispenser  120  includes a curved wall  150  that defines the base of accumulation chamber  171 . Wall  150  follows the general contour of diaphragm  171 , and is in contact with the diaphragm at the beginning of the accumulation cycle. This ensures that substantially all aerosol content stored in the radial section  174  escapes during the spray cycle, thereby preventing liquid aerosol content from pooling in the radial section. During the accumulation cycle, the diaphragm becomes axially displaced from wall  150  to define the radially extending portion  72  of the accumulation chamber, as described above. 
     Dispenser  120  includes a stem  155  that extends axially between conduit  142  and outlet end  146 . Stem  155  is radially displaced on one side from the axially inner portion of wall  154  so as to define an intake channel  156  that extends between conduit  142  and axial section  172  of chamber  171 . Stem  155  is radially displaced on its other side from the entire radial inner surface of wall  154  so as to define an outlet channel that extends between the axially extending section  172  and the outlet end  164 . The openings of channels  156  and  163  into the axial section  172  are axially displaced from one another by the amount of axial travel by the diaphragm  170  between the accumulation and spray cycles. 
     During the accumulation cycle, hub  177  is radially aligned with channel  163  to form a seal which prevents the aerosol content from escaping the accumulation chamber  171 . Accordingly, the aerosol content is only permitted to flow through intake channel  156  along the direction of arrow F into accumulation chamber  171 . Once the pressure within the chamber  171  has biased the diaphragm  170  and retainer  166  axially outwardly, hub  177  falls out of alignment with channel outlet channel  163  and becomes radially aligned with intake channel  156  to provide a blockage thereto. The aerosol content then flows from accumulation chamber  171  along the direction of arrow F, through outtake channel  163 , and out the outlet end  164 . 
     The above description has been that of preferred embodiments of the present invention. It will occur to those that practice the art, however, that many modifications may be made without departing from the spirit and scope of the invention. In order to advise the public of the various embodiments that may fall within the scope of the invention, the following claims are made. 
     Industrial Applicability 
     The present invention provides automated dispenser assemblies for dispensing aerosol can contents without requiring the use of electric power.