Patent Publication Number: US-6703590-B1

Title: Bottle warmer for disposable baby bottle

Description:
FIELD OF THE INVENTION 
     The present invention relates to apparatus for warming beverages stored in a bottle, and more particularly to a warmer for use with nursing bottles of the type utilizing disposable inner liners. 
     RELATED ART 
     FIG. 1 is an exploded perspective view showing a disposable baby bottle assembly  100  of a type including a bottle sleeve (holder)  110  and a disposable inner liner  120  that fits inside of sleeve  110 , and is held in place by a cap  130 . Sleeve  110  is a substantially cylindrical, hollow structure that is typically molded from a relatively stiff plastic. Sleeve  110  includes a substantially cylindrical outer wall  111  having a ring-shaped lower edge  113  defining a lower opening  114 , and a threaded upper edge  115  defining an upper opening  116 . Outer wall also defines an optional longitudinal slot  117  for receiving a slidable support member (not shown) therein. Liner  120  typically includes a pliable (e.g., plastic) bag or sac for storing a beverage (e.g., milk or baby formula), and in some instances is preformed to facilitate insertion into sleeve  110 . Liner  120  includes an open edge  122  and a bag-like body  125  that is typically inserted through upper opening  116  of sleeve  110  until open edge  122  rests on upper edge  115  of sleeve  110 . Cap  130  is a substantially ring-shaped structure that is molded from relatively stiff plastic, and includes threads (not shown) that mate with upper edge  115  of sleeve  110 . A rubber or plastic nipple  140  is typically mounted onto cap  130 . When assembled, a lip of cap  130  pinches open edge  122  of liner  120  and a lower edge (not shown) of nipple  140  against upper edge  115  of sleeve  110 , thereby forming a substantially enclosed beverage chamber defined by liner  120  and nipple  140 . Subsequently, as beverage is sucked out of liner  120  through an opening formed in nipple  140 , liner  120  collapses inside of sleeve  110 . After use, liner  120  is typically discarded, and sleeve  110 , cap  130 , and nipple  140  are typically washed and reused. Disposable nursers similar to disposable baby bottle assembly  100  are sold by Playtex Products Inc. of Westport, Conn., USA. 
     The milk and baby formula typically dispensed using disposable baby bottle assembly  100  are preferably consumed warm (i.e., above average room temperature). The heating method recommended by disposable baby bottle manufacturers is to hold the assembly  100  under hot tap water, or to place assembly  100  into a pan of warm water removed from heat source. Alternatively, these manufacturers recommend heating the beverage outside of liner  120 , and then pouring into liner  120  after cooling to a safe temperature. Liner manufacturers typically warn against using a direct heat source to heat a beverage stored in a liner due to the danger of overheating the beverage and bursting the liner. 
     While performing the recommended heating methods (e.g., hot tap water or warm water bath) is relatively convenient at home, such methods are typically not available when traveling. Moreover, heating the beverages outside of the liners is typically difficult when traveling, and may present a dangerous health risk by exposing the beverages to, contaminants while pouring the beverage into the liner. Consequently, beverages are often consumed from disposable baby bottles at an undesirable (e.g., room) temperature. 
     What is needed is an apparatus that quickly and safely warms beverages stored in disposable baby bottles to a desirable temperature. 
     SUMMARY 
     The present invention is directed to a bottle warmer for warming a beverage (e.g., baby formula or milk) stored in a disposable baby bottle assembly. The bottle warmer includes a housing having an opening for receiving the bottom edge of the baby bottle, a heat transfer element located inside of the opening that contacts the liner when the baby bottle sleeve is fully inserted into the housing, and a heat generator coupled to the heat transfer element such that heat is transferred to the liner at a preset rate and temperature, thereby safely and reliably heating the stored beverage without danger of overheating the beverage and/or bursting the liner wall. 
     In accordance with an embodiment of the present invention, the heat transfer element of the bottle warmer includes a cup-shaped container having a closed bottom wall, and a cylindrical outer wall that extends upward from the bottom wall and has a circular upper edge that defines an upper opening. The cup-shaped container is formed from a thermally conductive material such as stainless steel, aluminum or other metal, and may be coated with a non-stick material. The cup-shaped container is mounted in the bottle warmer housing over the heat generator such that, when the bottle assembly is mounted onto the bottle warmer, the upper edge of the heat transfer element slides between the sleeve wall and the liner, and the liner is inserted inside the cup-shaped container. When fully inserted, the liner rests against the bottom wall of the heat transfer element, and portions of the liner contact the cylindrical wall of the heat transfer element. By interposing the cylindrical wall of the heat transfer element between the sleeve and the liner in this manner, heat is efficiently transferred from the heat transfer element to the beverage without having to pass through the sleeve wall. Further, this arrangement maximizes surface contact between the cup-shaped heat transfer element and the beverage-filled liner inserted therein, thereby facilitating the even distribution of heat to the liner to reduce heating time and the danger of local “hot spots”. 
     In accordance with another embodiment of the present invention, a plastic or ceramic insert is mounted in the bottle warmer housing that supports the heat transfer element over the heat generator. The insert includes a donut-shaped bottom wall having a mounting structure formed thereon for holding the bottom wall of the heat transfer element, and a cylindrical outer wall that extends upward from the bottom wall and has a circular upper edge that defines an upper opening. A cylindrical groove is formed between the cylindrical wall of the heat transfer element, which has a relatively small diameter, and the cylindrical wall of the insert, which has a relatively large diameter. 
     In accordance with yet another embodiment of the present invention, a system is provided that includes a baby bottle warmer and a disposable baby bottle assembly in which the baby bottle sleeve and/or the bottle warmer are provided with a mechanism that turns the sleeve while the disposable baby bottle assembly is pushed into the bottle warmer, thereby causing the liner to slide on the surface of the heat transfer element to prevent sticking. 
     In accordance with another aspect of the present invention, the heat generator is a portable heat generating system that is powered by a fuel source mounted in the housing of the bottle warmer. In one embodiment, the heat generating system includes a valve and/or control switch, a heat generator, and a removable fuel source. The heat generator is mounted in the bottle warmer housing and located below the cup-shaped heat transfer element. In one specific embodiment, the heat generating system is a combustible gas burning system including a valve assembly for passing a combustible gas (e.g., butane) from a removable container to a gas-burning mechanism. A second manual switch is provided to initiate gas flow from container to the gas-burning mechanism, and the manual ON/OFF switch is used to facilitate ignition of the gas. The gas-burning mechanism includes a ceramic piece that is heated by the small gas flame, and is connected to the heat transfer element such that the heat transfer element acts as a heat sink for the ceramic piece. In accordance with a second embodiment, an electrical heating system includes a switch for passing an electric current from a removable battery to a resistive heating element. 
    
    
     The present invention will be more fully understood in view of the following description and drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing a conventional disposable baby bottle assembly; 
     FIG. 2 is an exploded perspective view showing a system including a conventional disposable baby bottle being mounted into a bottle warmer produced in accordance with an embodiment of the present invention; 
     FIG. 3 is a simplified cross-sectional side view showing the bottle warmer of FIG. 2; and 
     FIGS.  4 (A) and  4 (B) are simplified cross-sectional side view showing a conventional disposable baby bottle as it is mounted into the bottle warmer of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     FIG. 2 is an exploded perspective view showing a system including a bottle warmer  200  for warming a beverage (e.g., baby formula or milk) stored in disposable baby bottle assembly  100  (described above with reference to FIG. 1) in accordance with an embodiment of the present invention. Although the present invention is described below in the context of a portable unit for warming the contents of a disposable baby bottle, the present invention may be modified and/or utilized to heat or warm the contents of other container types that utilize a storage liner similar to that described above with reference to disposable baby bottle assembly  100 . 
     In the embodiment shown in FIG. 2, bottle warmer  200  includes a housing  210 , a heat transfer element  220  mounted in housing  210 , and a heat generator (not shown) also mounted in housing  210  and positioned below heat transfer element  220 . 
     Housing  210  includes a substantially cylindrical wall  212  that defines an upper (first) opening  214 . The diameter of opening  214  is larger than the diameter of lower edge  113  of bottle sleeve  110  such that disposable baby bottle assembly  100  can be inserted into housing  210  through opening  214 . Housing  210  also includes a protrusion  215  for controlling a heat generating system (discussed below), which is mounted in housing  210  such that the heat generating system selectively transfers heat to heat transfer element  220 . Manual control switches  217  and optional indicator lights  219  are provided on protrusion  215  to facilitate control of bottle warmer  200  in the manner described below. Housing  210  also includes an opening (not shown) for receiving a fuel cell  230  (e.g., a gas canister or a battery), which is partially shown in the lower portion of FIG.  2 . 
     Heat transfer element  220  and the heat generator (not shown) are mounted inside housing  210  such that heat transfer element  220  is exposed through opening  214 , and is positioned relative to opening  214  such that, when disposable baby bottle assembly  100  is inserted into opening  214 , heat transfer element  220  extends through lower opening  114  of sleeve  110  and contacts a lower end of liner  120 . As discussed in additional detail below, heat transfer element  220  is formed from a rigid, thermally conductive material (e.g., stainless steel), and is coupled to the heat generator such that heat generated by the heat generating system is transferred to heat transfer element  220 , which is turn passes the heat to liner  120 . 
     FIG. 3 is a simplified diagram showing bottle warmer  200  in additional detail. In addition to housing  210 , heat transfer element  220  and fuel source  230 , bottle warmer  200  includes a heat generator  310  and an optional insert  320 , which are described in additional detail below. 
     According to the specific embodiment shown in FIG. 3, heat transfer element  220  comprises a cup-shaped container having a closed bottom wall  221 , and a cylindrical wall  223  that extends upward from bottom wall  221  and has a circular upper edge  225  that defines an upper opening  227 . As discussed further below, cylindrical wall  223  has a diameter D 1  that is smaller than the diameter of the baby bottle sleeve. Heat transfer element  220  is formed from a thermally conductive material such as stainless steel or other metal, and may be coated with a non-stick material. The inventor believes that the further cylindrical wall  223  extends into sleeve  110 , the faster beverages stored in liner  120  are heated (i.e., due to the greater surface contact between liner  120  and cylindrical wall  223 ). However, a beneficial structure may also be provided using a shorter cylindrical wall  223 , or no cylindrical wall at all (i.e., only bottom wall  221  that extends through lower opening  114  to contact the bottom of liner  120 ). Therefore, unless specified, the appended claims are not intended to be limited to the structure shown in the figures. 
     A heat generator  310  is mounted in bottle warmer housing  210  below lower wall  221  of heat transfer element  220 . In one embodiment, heat generator  310  is a portable combustible gas burning system including a valve assembly (valve/switch)  312  for passing a combustible gas (e.g., butane) from a removable container (fuel source  230 ) to a gas-burning mechanism (heat generator)  310 . A switch  217 A is provided to initiate gas flow from container  230  to gas-burning mechanism  120 , and ON/OFF switch  217 B facilitates ignition of the gas to produce a small gas flame in gas-burning mechanism  310 . A controller/sensor  315  is provided to control the heating process by, for example, limiting heat generation to a predetermined period of time, or by sensing the temperature of heat transfer element  220 . Gas-burning mechanism  310  includes a ceramic piece that is heated by the small gas flame, and is connected to bottom wall  221  of heat transfer element  220  such that heat transfer element  220  acts as a heat sink for the ceramic piece. A suitable combustible gas burning system is disclosed in U.S. Pat. No. 4,699,123, entitled “Portable Heating Appliance”. 
     In accordance with an alternative second embodiment, an electrical heating system includes a switch  217 B for passing an electric current from a removable battery (fuel source)  230  to a resistive heating element (heat generator)  310 . 
     Optional insert  320  is mounted inside housing  210 , and includes a donut-shaped bottom wall  321 , a mounting structure  322  formed on the donut-shaped bottom wall, a cylindrical outer wall  323  extending upward from the bottom wall and having a circular upper edge  325  that defines an upper opening (groove)  327 . Mounting structure  322  is located inboard of cylindrical outer wall  323 , and is formed to receive and secure bottom wall  221  of heat transfer element  220 . Cylindrical outer wall  323  defines an inside diameter D 2  that is larger than outside diameter D 1  of heat transfer element  220 , and is also larger than the outer diameter of the baby bottle sleeve. Accordingly, cylindrical groove  327  is formed between cylindrical outer wall  323  of insert  320  and cylindrical wall  223  of heat transfer element  220 . In one embodiment, insert  320  is molded or otherwise formed from suitable plastic or ceramic materials. 
     According to another embodiment (not shown), the features of insert  320  may be integrally incorporated into housing  210  using known molding techniques. 
     The operation of bottle warmer  200  will now be described with reference to FIGS.  4 (A) and  4 (B), which are partial views taken from FIG.  3 . 
     Prior to operation, a room temperature or cold beverage is stored in liner  120  of bottle assembly  100 , and liner  120  is mounted in sleeve  110  as indicated in FIG.  4 (A). Bottle assembly  100  is manually positioned over bottle warmer  200  such that liner  120  is aligned with upper edge  225  of heat transfer element  220  and lower edge  113  of sleeve  110  is aligned over groove  327  formed between cylindrical outer wall  323  of insert  320  and cylindrical wall  223  of heat transfer element  220 . Bottle assembly  100  is then lowered such that liner  120  enters heat transfer element  220  and lower edge  113  of sleeve  110  enters groove  327 . Note that, due to possible sticking between liner  120  and heat transfer element  220 , it may be necessary to manually rotate sleeve  110  (as indicated by double-headed arrow) such that liner  120  slides in a transverse direction against the inner surface of heat transfer element  220 . Bottle assembly  100  is pushed downward in this manner such that upper edge  225  of heat transfer element  220  slides between sleeve  110  and liner  120 . As indicated in FIG.  4 (B), when bottle assembly  100  is fully inserted into bottle warmer  200 , a bottom end of liner  120  rests against bottom wall  221  of heat transfer element  220 , and side portions of liner  120  contact cylindrical wall  223  of heat transfer element  220 . By interposing heat transfer element  220  between sleeve  110  and liner  120  in this manner, heat is efficiently transferred from heat transfer element  220  to the beverage stored in liner  120  without having to pass through sleeve  110 . Further, this arrangement maximizes surface contact between heat transfer element  110  and the beverage-filled liner inserted therein, thereby facilitating the even distribution of heat to liner  120  to minimize heating time and the danger of local “hot spots”. 
     Referring again to FIG. 3, after the bottle assembly is inserted into bottle warmer  200 , the heat generating system is manually actuated using ON/OFF switch  217 A and, if necessary, fuel flow switch  217 B. When the heat generating system is turned on, valve/switch  312  facilitates the flow of fuel to heat generator  310 , which in turn generates heat that is transferred to heat transfer element  220 . In addition, an optional first indicator light (e.g., a red light emitting diode (LED))  215 R is turned on by controller  315  to indicate that heat generator  310  is working. When the beverage stored in liner  100  is subjected to heat for a predetermined period of time, or the upper portion of heat transfer element  220  reaches a predetermined temperature, controller/sensor  315  transmits a control signal to switch  312  that terminates the flow of fuel to heat generator  310 . In addition, the control signal from controller/sensor  315  turns off first indicator light  217 R, and turns on an optional second indicator light (e.g., a green LED)  217 G, thereby notifying the user that the bottle contents are at a temperature suitable for consumption. By automatically controlling the heating process in this manner, bottle warmer  200  facilitates safe and reliable heating of beverages stored disposable baby bottle assemblies. 
     Other modifications to the disclosed apparatus are also possible. For example, to facilitate turning (twisting) of the bottle sleeve during insertion into the bottle warmer, a modified system may provide a mechanism that turns the sleeve while the disposable baby bottle assembly is inserted into the bottle warmer, thereby facilitating insertion of the liner into the cup-shaped heat transfer element. In one possible embodiment, a set of teeth may extend from the outer surface of the sleeve that engage with helical grooves (threads) formed in the insert portion of the bottle warmer. As the bottle is inserted, engagement between the teeth and the helical grooves cause the sleeve to turn, thereby twisting the liner relative to the stationary cup-shaped heat transfer element. In another alternative embodiment, a non-portable heat generating system (e.g., an electric heater powered by normal household currents and a standard plug arrangement) may be used in place of the portable heat generating systems mentioned herein. Yet other modifications are also possible. Thus, the invention is limited only by the following claims.