Abstract:
A hose for carrying liquid, such as hot melt adhesive, within a predetermined elevated temperature range. The hose includes a tube or body portion which has an inlet end adapted to connect to a source of liquid, such as a supply tank, and a discharge end adapted to a connect to a liquid dispensing apparatus, such as an adhesive dispensing gun. At least two temperature sensing devices, each having an output end, are also operatively associated with the tube to sense the temperature of the liquid therein. An adapter has a first end selectively connected to the output end of the first temperature sensing device. The adapter also has a second end adapted to connect to a controller which is compatible with the first temperature sensing device and not the second temperature sensing device. With the first temperature sensing device connected to the adapter, it is operative to sense the temperature of the liquid in the tube. In contrast, because the second temperature sensing device is not connected to the adapter, it is inactive and provides no temperature information concerning the liquid in the tube. The hose further includes a second adapter which is capable of replacing the first adapter.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to hoses for carrying heated liquids, such as hot melt adhesives. 
     BACKGROUND OF THE INVENTION 
     Various manufacturing processes involve the transmission of a heated liquid from a supply tank, through a hose, and to a liquid dispensing device which deposits the heated liquid into a container or onto a substrate. Some of the heated liquids are hot melt adhesives which solidify at room temperature. Accordingly, a hot melt adhesive must be heated and thus liquified so it can flow from the supply tank, through the hose, and out the liquid dispensing device. To liquify and subsequently maintain the hot melt adhesive within an appropriate temperature range, the supply tank, the hose, and the dispensing gun are selectively heated by individual heating devices operatively associated with each respective component. To monitor the temperature of the hot melt adhesive throughout the application process, each component further includes some form of temperature sensing device which operates in conjunction with at least one heating device. A controller operates the heating device in response to signals from the temperature sensing device to maintain the hot melt adhesive within a predetermined temperature range. 
     Generally, separate temperature controllers are provided for the dispensing gun, the hose, and the supply tank. The hose will often incorporate a single temperature sensing device and a single heating device which are coupled to a wire harness extending from one end of the hose. This wire harness has a connector which connects to a complementary connector on the controller. The controller monitors the temperature detected from the temperature sensing device and activates the heating device as necessary. If the hose becomes clogged or otherwise damaged, any replacement hose must have an appropriate wire harness to fit the complementary connector of the controller. 
     In addition, care must be taken when replacing a pre-existing hose with a replacement hose as the single temperature sensing device in the replacement hose must be compatible with the controller used with the prior temperature sensing device in the pre-existing hose. For example, one particular temperature sensing device is a resistance temperature detector (RTD) which may be made from different materials, such as nickel or platinum. A nickel RTD must be connected to a controller compatible with a nickel RTD. If the RTD in the replacement hose is not matched to the appropriate, material-specific controller, the controller will provide erroneous temperature information about the hot melt adhesive in the hose and may cause the heating device to operate at dangerously high output levels based on the erroneous temperature information. Thus, a pre-existing hose having a nickel RTD must be replaced by a hose also having a nickel RTD in order that the pre-existing controller will remain compatible with the nickel RTD. 
     Occasionally, a change in the manufacturing process will require dispensing a different heated liquid at a substantially higher or lower temperature range than that used for a prior heated liquid. In this situation, the prior temperature sensing device in the heated hose may not be suited for measuring those higher or lower temperatures. Because the heated hose includes only a single temperature sensing device, the heated hose must be replaced by a different heated hose having a different temperature sensing device suited for measuring the different liquid temperatures. If a different temperature sensing device is used, the existing controller must also be changed to match the different temperature sensing device. A controller may also have to be replaced if it becomes damaged or inoperative. Unfortunately, if the replacement controller has a connector which does not match the connector of the wire harness on the hose, the user must install a new hose with the appropriate connector. Thus, a manufacturer must maintain a large inventory of heated hoses and controllers to accommodate different manufacturing processes. 
     In light of the drawbacks discussed above, it would be desirable to provide a heated hose for connecting a supply tank to a liquid dispensing unit where the heated hose incorporates a plurality of different types of temperature sensing devices, such as RTDs made of different materials or thermocouples. It would also be desirable if the heated hose had an adapter cable which was configured to connect the wire harness of the hose to the controller. As such, the single hose could be used with a variety of different controllers configured to operate with the plurality of different temperature sensing devices and only the adapter cable would have to be modified or replaced as opposed to the entire hose. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a hose which overcomes the drawbacks associated with previous heated hoses connecting supply tanks to liquid dispensing devices. The hose includes a tube or body portion which has an inlet end adapted to connect to a source of liquid, such as a supply tank, and a discharge end adapted to a connect to a liquid dispensing apparatus, such as an adhesive dispensing gun. At least two temperature sensing devices, each having an output end, are also operatively associated with the tube to sense the temperature of the liquid therein. An adapter has a first end selectively connected to the output end of the first temperature sensing device. The adapter also has a second end adapted to connect to a controller which is compatible with the first temperature sensing device and not the second temperature sensing device. With the first temperature sensing device connected to the adapter, it is operative to sense the temperature of the liquid in the tube. In contrast, because the second temperature sensing device is not connected to the adapter, it is inactive and provides no temperature information concerning the liquid in the tube. 
     In one embodiment, the temperature sensing devices are RTDs with at least one RTD constructed of platinum and at least one RTD constructed of nickel. However, the temperature sensing devices could also be thermocouples or any other suitable temperature sensing device. In addition to having only one type of temperature sensing device per hose, the hose could include a combination of different types of temperature sensing devices, such as a mix of RTDs and thermocouples on the same hose. 
     In one aspect of the invention, the hose includes a wire harness which has a connector coupled to the output ends of the first and second temperature sensing devices. The adapter is connected to the connector such that only one of the first and second temperature sensing devices is active while the other temperature sensing device is inactive. 
     In another aspect of the invention, the hose includes a second adapter which is capable of replacing the first adapter. Like the first adapter, the second adapter has first and second ends. However, the first end of the second adapter is selectively connected to the output end of the second temperature sensing device, not the first temperature sensing device. The second end is adapted to connect to a controller compatible with the second temperature sensing device, but not the first temperature sensing device. As such, the second temperature sensing is operative to sense the temperature of the liquid in the tube and the first temperature sensing device is inactive and provides no temperature information about the liquid in the tube. 
     In further accordance with the principles of the present invention, an adapter is provided for electrically coupling a hose having at least first and second temperature sensing devices to a controller compatible with only one of the first and second temperature sensing devices. The adapter includes an adapter cable with first and second ends and a connector. The connector is adapted to selectively mate with only the first temperature sensing device so that the first temperature sensing device is operatively coupled to the adapter cable. The second end of the adapter cable is adapted to electrically couple to the controller such that the first temperature sensing device is electrically active and the second temperature sensing device is electrically inactive. 
     Various additional advantages, objects and features of the invention will become more readily apparent to those of ordinary skill in the art upon consideration of the following detailed description of the presently preferred embodiments taken in conjunction with the accompanying drawings. 
    
    
     DETAILED DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of the hose of the present invention connecting a supply tank to an adhesive dispensing gun; 
     FIG. 2 is an enlarged partial cross-sectional plan view of the hose of FIG. 1; 
     FIG. 3 is an enlarged plan view of the adapter shown in FIG. 1; 
     FIG. 4 is a partial end view of the connector of the wire harness shown in FIG. 2; 
     FIG. 5 is an end view of a connector at one end of the adapter cable of FIG. 3; and 
     FIG. 6 is an end view of a connector at the other end of the adapter cable of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to FIG. 1, an adhesive dispensing apparatus  10  includes a hose  12  constructed in accordance with the principals of the present invention. The hose  12  connects a pump  14 , which is coupled to supply tank  16 , to a manifold  18 , which is coupled to an adhesive dispensing gun  20 . As such, pump  14  can transport an adhesive  22 , such as hot melt, for example, from supply tank  16  via hose  12  to adhesive dispensing gun  20 . The adhesive dispensing gun  20  selectively dispenses adhesive  16  onto a substrate  24  such as a nonwoven web used in the construction of a diaper. A heater  26  is associated with supply tank  16  and is selectively controlled to maintain the adhesive  22  within supply tank  16  within a predetermined elevated temperature range. The hose  12  includes an wire harness  28  which is connected by an adapter  30  to a controller  32  which is also associated with the supply tank  16 . 
     With reference to FIG. 2, the hose  12  includes a tube  40  with an inlet end  42  which connects to pump  14  and a discharge end  44  which connects to manifold  18 . The tube  40  is advantageously constructed of Teflon™ and is covered end to end by a steel braid cover  46 . Steel braid cover  46  is wrapped by at least one layer of tape  47 , preferably silicon tape. It is believed that the tape  47  helps to reduce abrasion which might occur if components were otherwise wrapped in direct contact with the steel braid cover  46 . The hose  12  further includes a heating device  48  which is wrapped around the steel braid cover  46  along substantially the entire length of the tube  40 . One end of the heating device  48  is operatively connected to a connector  50  at the terminal end of wire harness  28 . Two temperature sensing devices  52 ,  54  also wrap around the tube  40  and are operatively connected to connector  50 . The temperature sensing devices  52 ,  54  are preferably resistance temperature detectors (RTD) which sense the temperature of the adhesive  22  flowing through tube  40 . Alternatively, one or both of temperature sensing devices  52 ,  54  could be thermocouples or any other suitable temperature sensing device. Though the RTDs  52 ,  54  are not to be limited to any particular material, RTD  52  is preferably constructed of nickel and RTD  54  is preferably constructed of platinum. For a given application, only one of the RTDs  52 ,  54  is operatively connected to controller  32  to monitor the temperature of the adhesive  22  flowing through the tube  40 ; the other RTD remains inactive. A ground wire  56  electrically connects inlet end  42  and discharge end  44  to connector  50  of wire harness  28 . 
     An insulative tape  58  is wrapped around heating element  48 , temperature sensing devices  52 ,  54 , and ground wire  56 . Three insulative layers  60 ,  62 ,  64  are wrapped around the insulative tape  58  to help reduce heat loss from the heated adhesive  22 . Preferably, the insulative layers  60 ,  62 ,  64  are constructed of fiberglass. Another layer of tape  66 , such as electrical tape, is wrapped around the outside of insulative layer  64 . A braided plastic cover  68  covers the electrical tape  66  to provide a protective cover for the outside of the hose  12 . Cuffs  70 ,  72  are placed over the respective inlet and discharge ends  42 ,  44  to provide additional protection to hose  12  and its electrical components against potentially damaging elements such as water. Preferably, cuffs  70 ,  72  are made from high temperature plastic. 
     With reference to FIG. 3, adapter  30  includes an adapter cable  74  which has oppositely disposed connectors  80 ,  82 . Adapter cable  74  includes a plurality of wires  83  which interconnect connector  82  to connector  80 . Connector  50  includes a latch  84  (FIG. 2) which operatively engages pins  86 ,  88  to positively secure connector  50  to connector  82 . As shown in FIG. 4, connector  50  includes six electrical connecting members  90 , preferably pins, which align with and are inserted into six complementary electrical connecting members  92 , preferably ferrules, in connector  82  (FIG.  5 ). Two of the six electrical pins  90  are connected to the heating element  48 ; two electrical pins  90  are connect to one RTD  52 ; and the two electrical pins  90  are connected to the other RTD  54 . The ground wire  56  is operatively connected to the connector  50 , but not to any of the six electrical pins  90 . 
     Connector  80  includes fifteen electrical connecting members  94 , preferably pins, in a 3×5 pattern (FIG. 6) which insert into complementary electrical connecting members (not shown), preferably ferrules, in connector  96  of controller  32 . It will be appreciated that the connector  80  may take on several different configurations as dictated by the configuration of the connector  96  of the controller  32 . For instance, the connector  96  may be a nine-pin connector instead of the fifteen-pin connector illustrated in FIG.  6 . The connector  96  may be round or the controller  32  may not have a connector  96  at all, but instead have a terminal strip in which individual wires  83  of adapter cable  74  are individually connected. 
     Once the controller  32  is chosen, the adapter  30  can be manufactured such that it will electrically couple only the proper RTD, either  52  or  54 , to the controller  32 , leaving the other RTD inactive. Although the connector  82  of adapter cable  74  includes six ferrules  92 , a typical installation utilizes only four of the six ferrules  92 . For example, if a nickel-based controller  32  is chosen, then only the nickel-based RTD  52  gets connected to the controller  32 . Accordingly, only the two ferrules  92  associated with the pins  90  connected to the nickel-based RTD  52  are employed. In addition, the two ferrules  92  associated with the heating device  48  are employed. After the connector  82  is properly configured, connector  80  is configured such that the controller  32  is electrically coupled to RTD  52  and heating device  48 . 
     The controller  32  monitors the temperature from only one of the two RTDs  52 ,  54  and selectively operates the heating element  48 . The controller  32  is designed to operate with a specific RTD made of a specific material. For instance, if the controller  32  is designed to operate with a platinum RTD, then the other RTD will be inactive and not used to measure the temperature of the adhesive  22 . To monitor the temperature from one RTD and not the other, the connector  80  will be configured so that the controller  32  will be operatively coupled only to the desired RTD. However, if the hose  12  is disconnected from the adhesive dispensing apparatus  10  and installed on a different adhesive dispensing apparatus with a controller designed to operate with a nickel RTD, then the only change will be to the adapter  30 . More specifically, a different adapter will be used so that the nickel RTD, previously inactive, will be electrically coupled to the new controller and the platinum RTD will be inactive. As such, the hose  12  can be used on a wide variety of adhesive dispensing apparatus  10  as long as there is a different adapter  30  which is specifically configured to connect to the different controllers. Advantageously, one hose  12  can be used for many different dispensing applications with the need to stock a variety of specifically configured adapter  30 . Although hose  12  has been described herein as having multiple insulation and protective layers, the principles of the present invention are equally applicable to any hose construction having a tube and at least two temperature sensing devices operatively associated therewith. 
     Hose  12  of the present invention provides an inherent safety feature not available in prior heated hoses. A prior heated hose typically includes only one RTD, such as a nickel- or platinum-based RTD, that is matched with an RTD-specific controller. When that heated hose is replaced, the replacement hose must include an RTD of the type in the old heated hose in order that it properly functions with the pre-existing controller. If a heated hose is installed with a different type RTD, the controller will erroneously interpret the temperature signals from the different type RTD, causing the heating device to operate at dangerously high output levels based on the erroneous temperature information. 
     Hose  12  of the present invention alleviates the above-mentioned safety concern. For example, connector  82  of adapter  30  is specifically configured to connect only one temperature sensing device, for example RTD  52 , to the controller  32 , leaving the other temperature sensing device or RTD  54  electrically inactive. Thus, when hose  12  is replaced by another hose  12  and all other components remain in place, only RTD  52  in replacement hose  12  will be electrically coupled to controller  32  as connector  82  of pre-existing adapter  30  was already configured to activate only RTD  52 , leaving RTD  54  inactive. Thus, by replacing a pre-existing hose  12  with a replacement hose  12 , the proper RTD will always be correctly coupled to controller  32  and heating device  48  will not respond to erroneous temperature information provided by controller  32 . 
     In operation, the hose  12  is installed to connect pump  14  and thus supply tank  16  to manifold  18  and ultimately to adhesive dispensing gun  20 . The adapter  30  which is specifically designed for the particular controller  32  is then connected between the wire harness  28  and the controller  32 . As such, the heating device  48  and one of the RTDs  52 ,  54  are operatively coupled to the controller  32 . The adhesive  22  which is generally in a solid state when at room temperature is then heated by heater  26  to a predetermined elevated temperature range to make the adhesive  22  flowable. Once the adhesive  22  reaches the predetermined elevated temperature range, the pump  18  is activated to selectively pump the adhesive  22  to the adhesive dispensing gun  20  as required by the particular dispensing application. To ensure that the adhesive  22  remains in its liquid condition and at the predetermined elevated temperature range, the active RTD (either  52  or  54 ) senses the temperature of adhesive  22  in hose  12  and heating device  48  is selectively operated to heat the hose  12 . If the dispensing process is stopped and the adhesive dispensing apparatus  10  is shut down, some amount of adhesive  22  may remain in the hose  12 . When allowed to cool, the adhesive  22  solidifies and effectively blocks the tube  40 . Consequently, when the adhesive dispensing apparatus  10  is put back into operation, the heating device  48  first must be activated to liquify the adhesive  16  in hose  12  to make it flowable again. Depending on the application and the type of adhesive used, the temperature of adhesive  22  is maintained between about 200° to about 500° F. Preferably, the hose  12  is configured to withstand operating pressures up to about 1500 psi. 
     The hose  12  can be manufactured in a variety of predetermined lengths between 7 and 60 feet, although longer lengths could be accommodated. The tube  40  preferably has an internal diameter of between about ⅜ inch to about ⅝ inch. The adapter  30  can be manufactured in a variety of predetermined lengths between 3 and 16 feet, although longer lengths could be accommodated. 
     Unlike a thermocouple which measures temperature at a particular spot on a surface, an RTD can sense temperature over an predetermined area. To that end, RTDs  52 ,  54  preferably measure or sense the temperature along an 8 to 10 inch section of the tube  40 . The location of this sensing section is dependent on the overall length of the hose  12 . For hoses less than or equal to eight feet in length, the sensing section of RTDs  52 ,  54  is placed approximately 6 inches away from the discharge end  44 . For hoses greater than eight feet in length, the sensing section of RTD  52 ,  54  is placed approximately three feet away from the discharge end  44 . 
     Although hose  12  has been described above as having two temperature sensing devices  52 ,  54  which are preferably RTDs, the two temperature sensing devices  52 ,  54  could also be thermocouples or any other suitable temperature sensing device. In fact, the temperature sensing devices  52 ,  54  need not be of the same type on the same hose  12 . In other words, temperature sensing device  52  could be a thermocouple and temperature sensing device  54  could be an RTD. Further, more than two temperature sensing devices could be integrally formed on hose  12  so that any number of RTDs and thermocouples could be part of the same hose  12 . Furthermore, although hose  12  is shown having only one wire harness  28  extending therefrom to which RTDs  52 ,  54  are coupled, hose  12  could include a separate wire harness for each temperature sensing device operatively associated with hose  12 . As such, an appropriate adapter  30  would connect to the appropriate wire harness depending on the specific RTD that would be operative or active. The other wire harness would not be used and its associated RTD would be inactive. 
     While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in considerable detail in order to describe the best mode of practicing the invention, it is not the intention of applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the invention will readily appear to those skilled in the art. The invention itself should only be defined by the appended claims