Patent Publication Number: US-6711934-B2

Title: Chemical dispensing system

Description:
This application is a Divisional Application of application Ser. No. 09/695,114 filed Oct. 24, 2000 now U.S. Pat. No. 6,464,772. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of chemical dispensing systems, and more particularly to such systems in which a number of liquid chemicals are dispensed selectively from chemical reservoir pods to a number of washing machines according to wash formula requirements. 
     BACKGROUND OF THE INVENTION 
     Commercial and institutional laundry facilities typically employ a plurality of washing machines in an automated system including a plurality of laundry chemical supply stations. The system has a controller which has in memory, or is supplied via an input device a formula for each type of load to be washed. The formula determines the quantity of each laundry chemical, for example detergent, bleach, water treatment, fabric softener, etc., as well as the operating times for each washing cycle. In addition to control of the quantity of each chemical, the formula specifies that the chemicals must be injected in a prescribed sequence and at the proper time for best results. Since commercial and institutional laundries are likely to use relatively large quantities of several chemicals, the accuracy of the quantity delivered is critical both to the quality of the washing results and to the operational efficiency of the laundry plant. 
     A known system for commercial washing operations is taught in U.S. Pat. No. 5,590,686 to Prendergast, entitled Liquid Delivery Systems. The Prendergast patent teaches the use of a flowmeter to control the amount each chemical that is delivered from its chemical reservoir to the washing machine. The flowmeter is connected to the discharge end of a chemical supply piping system so that chemical flow from any of several chemical reservoirs passes through the flowmeter. The major drawback to the Prendergast device is that a flowmeter is known to have limited accuracy, and in a commercial or institutional laundry system, accurate control of the quantity of each chemical is important. By its nature, a flowmeter is designed and calibrated to measure a liquid of a particular viscosity and at a particular rate of flow. Since there is a single flowmeter in a system dealing with a plurality of chemicals, and since the chemicals generally will have differing viscosities, the amount of any one or several of the chemicals will not be accurately measured. A further drawback of a chemical delivery system that uses a flowmeter to measure chemical delivery quantity is that if the amount of a particular chemical in a reservoir is less than the amount called for by the formula, there is no means to signal an insufficiency before the chemical supply is totally depleted. In this case, either the laundry batch will run with one or more chemicals at lower than the specified quantity or the process will have to be stopped to wait for chemical replenishment. 
     Therefore, it is an object of the present invention to provide a chemical delivery system capable of achieving accurate control of the quantity of each of a plurality of chemicals from individual sources. 
     It is an additional object of the invention to verify that sufficient chemical is available for a next wash cycle to run. 
     These and other objects of the present invention will become apparent through the disclosure of the invention to follow. 
     SUMMARY OF THE INVENTION 
     The invention provides a system for automatically dispensing a defined volume of one or more chemicals for use in one or more washing machines. Each chemical is stored in a reservoir pod having a chemical pressure sensor connected adjacent its bottom, a chemical output valve connected into an output pipe, and an overflow sensing switch connected adjacent its top. A single output pump is connected by supply piping between a water supply tank and the washing machines, with each chemical output valve connected to the piping. A diverter valve connects each washing machine with the supply piping. An output pressure sensor is connected between each diverter valve and its respective washing machine. 
     When a washing cycle is started, a controller requests a selected quantity of each required chemical according to a formula. The controller, through each chemical pressure sensor, verifies that sufficient quantity of each required chemical is available. If insufficient quantity is available, the cycle is suspended until the chemical supply is replenished by activation of a chemical refill pump to refill the deficient pod. If sufficient quantity is available, the single output pump is activated to draw water through the piping, and a diverter valve is set to channel the water to the requesting washing machine, with the output pressure sensor verifying that water is flowing. After a selected quantity of water has entered the washing machine, a first chemical output valve is opened and the chemical flows into the water flow in the piping. The chemical pressure sensor for the pod being accessed sends continuous pressure data to the controller which determines when the selected volume of chemical has been supplied and shuts the chemical output valve. Additional chemicals from other pods are added as required. 
     The system also includes calibration routines for the pressure sensors and a test routine for verification that power and water are available and the pumps and valves operate properly. A modified system is adapted for use in the supply of chemicals to “tunnel” type-washing equipment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order for the invention to become more clearly understood it will be disclosed in greater detail with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic depiction of the chemical dispensing system disclosed as applied to a bank of conventional washing machines. 
     FIG. 2 is a schematic depiction of the chemical dispensing system disclosed as applied to a batch conveyor, or tunnel, washing machines. 
     FIG. 3 is a flowchart of the chemical reservoir pod refilling process according to the invention. 
     FIG. 4 is a flowchart of the water tank refilling process of the invention. 
     FIGS. 5 a  and  5   b  comprise a flowchart of the chemical dispensing process of the invention. 
     FIG. 6 is a flowchart of a calibration routine of the invention. 
     FIGS. 7 a  and  7   b  comprise a flowchart of a diagnostic routine for the apparatus of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The chemical dispensing system of the present invention is incorporated into a commercial laundry facility  10  as depicted in FIG.  1 . Water is supplied to the system from water supply tank  16  through a supply pipe  12  to a number of process units  40   a ,  40   b , and  40   c , e.g., washing machines. An output pump  36  is positioned in supply pipe  12  with its discharge end connected to first 3-way diverter valve  34   a . One discharge outlet of first 3-way diverter valve  34   a  is connected to first process unit  40   a , and its second discharge outlet is connected in series fashion to a second 3-way diverter valve  34   b . Second 3-way diverter valve is similarly connected to second process unit  40   b  and to a third 3-way diverter valve  34   c . Third 3-way diverter valve  34   c  is connected at one of its discharge outlets to third process unit  40   c  and its other discharge outlet back to water supply tank  16 . 
     While the preferred embodiment of the invention is depicted with three process units and four chemical reservoir pods, differing numbers of process units and chemical pods are within the scope of the invention. 
     Water supply tank  16  is refilled through a water valve  20  that is actuated when water level sensor  22  signals inadequate quantity of water available in water supply tank  16  to fill at least one washing machine. Water level sensor  22  continuously monitors the amount of water available in tank  16 . Water level sensor  22  is, according to the preferred embodiment, a pressure-sensitive transponder such as model MPX5010GP by Motorola. Alternate means of controlling the amount of water available in water supply  16 , such as a “float valve,” would perform the required basic function. However, it is to be understood that electronic signaling means, such as water level sensor  22  enables chemical dispensing system  10  of the invention to change the required quantity of water in water supply tank  16  by data entry or programming means. 
     As will be apparent to those skilled in the trade, each pressure sensor, each valve, each pump, and each process unit is in communication with a system controller (not shown) that receives input signals from, and transmits commands to, each such controllable unit. The controller is programmed with a number of formulas, including amounts and types of chemicals to be used, amount of water used, the time in the operation cycle for each liquid to be infused into the process unit, the operation cycle time, etc. The controller also is able to retain in memory pressure sensor values at varied conditions pursuant to a calibration protocol described below. 
     Output pressure sensors  38   a - 38   c  are respectively connected to each connective delivery pipe  42   a - 42   c  between 3-way diverter valves  34   a - 34   c  and process units  40   a    40   c . When output pump  36  operates, and first 3-way diverter valve  34   a  is set to pass liquid through to second 3-way valve  34   b , for example, with second 3-way valve set to divert liquid passing therethrough to second process unit  40   b , output pressure sensor  38   b  senses the liquid pressure in delivery pipe  42   b . If the sensed liquid pressure is outside of an established range, the system controller shuts down the system and activates an alarm as described more fully below. With the sensed liquid pressure in the established range, output pump  36  operates for a time computed at the sensed pressure to deliver the required amount of water to the requesting process unit. At the end of the computed time, output pump  36  is stopped. 
     Each chemical pod  26   a - 26   d  has a respective chemical pressure sensor  30   a - 30   d  connected adjacent its lower end. Chemical pressure sensors  30   a - 30   d  are, according to the preferred embodiment, a pressure-sensitive transponder, for example Motorola model MPX5050GP. Chemical pressure sensors  30   a - 30   d  continually monitor the pressure as caused by the height and specific gravity of the liquid within each chemical reservoir pod  26   a - 26   b  and send a signal thereof to the system controller. According to the preferred embodiment, each chemical pod  26   a - 26   d  is similar in height, with the diameter, and thus the volume, of each pod differing according to the relative consumption per washing batch of the chemical stored therein. In other words, a chemical pod that is to store detergent, which is used in relatively large amounts, would have a greater diameter than a chemical pod that is to store, e.g., fabric softener. Thus, each chemical pod can be sized to contain, e.g., the amount of chemical that will be required to process two or three batches in one process unit  40 . In order to enhance the accuracy of the volumetric measurements derived from each chemical pressure sensor  30 , the height of each chemical pod is preferred to be as great as practical. If a pressure sensed by one of chemical pressure sensors  30   a - 30   d  corresponds to a chemical volume that is below an established minimum, the system controller activates the respective chemical refill pump  24   a - 24   d  which operates to refill the respective chemical pod  26   a - 26   d  from the appropriate chemical supply  18   a - 18   d . The controller will not start a wash cycle until all chemicals are available in adequate supply. The operating chemical refill pump  24  is stopped when the respective chemical pressure sensor  30  indicates that chemical pod  26  is substantially full. An overflow switch  32   a - 32   d  is provided in each tank as a failsafe to stop the operating refill pump  24  in the case that the chemical pressure sensor  30  signal did not deactivate the refill pump  24 . Pods  26   a - 26   d  each have a vent hole in the upper end thereof to avoid pressure differentials due to air entrapment. Chemical refill pumps  24  and output pump  36  are preferably of the air-actuated diaphragm type. Chemical output valves  28  are also preferably of the air-actuated type. Three way diverter valves  34  are preferably electrically actuated. 
     At a preset time after output pump  36  is activated and water is flowing through supply pipe  12  to a requesting process unit  40 , a first chemical output valve  28   a - 28   d  is opened to allow the chemical stored in the respective chemical pod  26   a - 26   d  to flow into supply pipe  12 . The water flowing in supply pipe  12  carries the chemical through output pump  36  to the requesting process unit. If more than one chemical is being requested and the chemicals are not incompatible, more than one chemical output valve  28   a - 28   d  is opened simultaneously. Otherwise each chemical output valve  28   a - 28   d  is operated in sequence. Each of the operating chemical output valves  28   a - 28   d  remains open until the system controller determines from signals received from the respective chemical pressure sensor  30   a - 30   d  that the requested volume of chemical has entered supply pipe  12 , and then the chemical output valve  28   a - 28   d  is closed. 
     When the operating process unit  40   a - 40   c , i.e. washing machine, has completed its cycle, it discharges the used water to an available drain (not shown). 
     A second known industrial washing machine is of the continuous process type, also known as a “tunnel” washing machine, as schematically illustrated in FIG.  2 . In this type washing machine, the garments or other materials to be washed are placed in a first end of a long, tubular, apparatus having a series of segments. The tube normally is already filled with water. Required chemicals are added to the water in each segment according to the operation to be done. The garments are agitated with the water and chemicals for a set time and then moved to a second segment. Each segment of a tunnel washer is supplied with additional chemicals as required and additional water to move the chemicals through the supply lines. When the garments arrive at the last segment of the machine, the water is comparatively clean, as are the garments. The clean garments are removed from the last segment and are dried in a separate machine operation, for example a tumble dryer. 
     Referring now to FIG. 2, the inventive chemical dispensing system as described above is illustrated in an alternate embodiment for use with a continuous process tunnel washer  44 . Tunnel washer  44  comprises operating segments K, L, M, N, O, and P. Garments or other items for cleaning are placed first into segment K and are moved sequentially in the direction indicated by arrow X toward segment P. The primary water supply to tunnel washer  44  enters segment P through supply pipe  12 ′ and the water flows in the direction indicated by arrow Y toward segment K. In this manner, the cleanest water is in contact with the cleanest items being processed, i.e., in segment P. Conversely, the dirtiest items enter segment K and are treated initially in comparatively dirty water. 
     The washing of clothes in tunnel washer  44  involves introducing cleaning chemicals in sequential steps that parallel the movement through washer  44  of items being washed. The apparatus schematically illustrated in FIG.  2  and described below relates to a particular embodiment and is not considered a limitation on the scope of the invention. Upon starting the washing process in tunnel washer  44 , after garments or other items and process water are placed into segment K, output pump  36   a  is activated and chemical supply valves  28   a  and  28   b  are opened. Output pressure sensor  38   a  ascertains that liquid flow in delivery pipe  42   a  is occurring. Once chemical pressure sensors  30   a  and  30   b  have ascertained through the system controller (not shown) that sufficient quantity of each of the requested chemicals has been supplied, output pump  36   a  is set to operate for a further time interval to clear delivery pipe  42   a  of residual chemicals. 
     A similar process to that described above with respect to segment K and associated output pump, chemical reservoir pod, valve, and pressure sensors takes place simultaneously in respect to segments L, M, N, and O. Once the first batch of items to be washed is passed from segment K to segment L, a second batch is placed in segment K, and so forth for segments M, N, O, and P. Each segment of tunnel washer  44  may have a different number of chemical reservoir pods  26 , according to the process to be done in that segment. As segment P is the final processing segment in tunnel washer  44 , no chemicals are employed and the items that were washed are now merely rinsed with clear water. 
     The operation of the apparatus of the invention is best understood with reference to FIGS. 3-7. FIGS. 3-7 are principally directed to the invention as it pertains to a number of conventional washer units, but will be understood to relate similarly to a tunnel washer with minor modifications. FIGS. 3-7 illustrate, by way of flowcharts, a group of software sub-routines that are incorporated within the invention program. 
     FIG. 3 shows a diagrammatic flowchart of a process for validating the function of and refilling the chemical storage pods as described above in relation to the apparatus employed in the practice of the invention. The operation is started at step  50  and moves to the first pod ( 26   a  of FIG. 1) in step  52 . The system then checks the pressure sensor ( 30   a  of FIG. 1) to determine in Step  54  if the level of chemical in this pod is low. As noted above, the system controller (not shown) computes the volume of chemical in each chemical pod  26  (FIG. 1) based on the reading of the respective chemical pressure sensor  30 . If the reading of this chemical pressure sensor is low, the system checks at step  56  whether the respective chemical output valve ( 28  of FIG. 1) is open. If the chemical output valve is open, the system checks at step  58  if the respective refill pump is on, and if so, stops the refill pump at step  64 . If the refill pump is not on at step  58 , or if the refill pump was on and was turned off at step  64 , the process goes to step  82  which increments to the next chemical reservoir pod. At step  56 , if the chemical output valve was not open, the respective refill pump is started at step  60 , after which the connected chemical pressure sensor is checked to determine at step  62  if the level of liquid in the chemical reservoir pod is rising. If the level of liquid is rising, the controller determines whether the chemical pod is full at step  66 . If the chemical pod is full, the pump is stopped at step  64  and the process goes to the next pod at step  82 . If the level of liquid is determined at step  62  not to be rising, an alarm is activated at step  68  showing that the chemical product supply is low and the process goes to step  82 . 
     If the controller determines at step  54  that the pod level is not low, a determination is made at step  70  of whether the level in the chemical pod is changing. If the level is not changing, the process goes to step  82 . If the level is changing, the determination is made at step  72  of whether the level is rising or falling. If the level is rising, the system checks whether the respective refill pump is operating at step  74 . If the pump is on, the process goes to step  82 . If the pump is off, an overflow alarm is set and the system is shut down at step  76 . If, at step  72 , the level of liquid in a chemical pod was found to be falling, a determination is made as to whether the output valve is open at step  78 . If the output valve is open, the process goes to step  82 . If the output valve is not open, an alarm indicating liquid loss is set and the system is shut down in step  80 . 
     Referring now to FIG. 4, a sub-routine for verifying and maintaining the level of water in the water supply is shown. The program is started at step  100  and checks whether the pressure in the tank, as indicated by the water pressure sensor ( 22  of FIG.  1 ), is low at step  102 . If the pressure is below a set minimum, an alarm is set at step  104  to indicate the tank is low and the output pump is not permitted to operate. The tank-filling valve ( 20  of FIG. 1) is opened at step  106 , and a determination whether the water level in the tank is rising is made at step  108 . If the level is rising, the process returns to step  100 . If the level is not rising, an alarm is set at step  110  to indicate that the water supply is not functioning. If the query at step  102  indicates that the tank pressure is not low, the tank empty alarm, if set, is deactivated at step  112 . At step  114 , it is determined whether the water pressure is high. If the water pressure is not above a set maximum, the tank-filling valve is opened at step  106 , and the sequence through steps  108  and  110  is executed. If the water pressure is at or above the maximum, the tank-filling valve is closed at step  116  and a determination of whether the tank water level is constant is made at step  118 . If the water level is constant, the process returns to step  100 . If the water level is not constant, an alarm is set at step  120  to show an overflow and the system is shut down. 
     A flowchart for the dispensing of requested chemicals is provided in FIGS. 5A and 5B. Beginning with FIG. 5A, the system starts at step  130 , then moves to step  132  to poll all process units ( 40  of FIG. 1) for data, the determination of such data being made at step  134 . If there are no data from the units, a determination is made at step  136  whether there are any data in the system queue. If there are no data in the queue, the process returns to step  130 . If there were data at the units as determined at step  134 , step  138  determines whether the data is a formula number or a chemical request. If the data is a chemical request, a determination of whether the output pump is on is made at step  140 . If there were data in the queue, as determined at step  136 , a determination of whether the output pump is on is made at step  140 . If the output pump is on as found in step  140 , the data is added to the queue at step  142 . If the output pump is not on, an amount of chemical requested is looked up according to the specific formula, washer, and event at step  146 . The amount of each chemical required for the formula, washer, and event is compared to the amount in each chemical pod to determine if each pod ( 26  of FIG. 1) has enough chemical is made at step  148 . If there is enough chemical in each pod to fulfill the chemical requirement, the chemical dispensing cycle is started at step  156  and the process returns to step  130 . If there is not enough chemical in any one pod, the system waits one minute at step  150 . At a checkpoint whether one minute has passed at step  152 , if not, the process returns to step  130 . If one minute has passed and the chemical quantity is still inadequate, the chemical product alarm on the requesting washer is set at step  154  and the process returns to start at  130 . 
     Referring now to FIG. 5B, after the dispensing cycle has been initiated at step  156  in FIG. 5A, the output pump ( 36  of FIG. 1) is started and the diverter valve ( 34  of FIG. 1) is set for the requesting washer in step  158 . The output pressure is checked at output pressure sensor ( 38  of FIG. 1) in step  160 . If output pressure is not acceptable, an output error alarm is set and the system is shut down at step  162 . If output pressure is acceptable, a check for zero output pressures at additional diverter valves and pressure sensors is made at step  164 . If a non-zero output pressure is sensed at any other pressure sensor, a diverter valve error message is set and the system is shut down at step  166 . If all other pressures are sensed as zero, the appropriate chemical output valve(s) ( 28  in FIG. 1) is (are) opened at step  168 . Chemical pod level consistency is checked at step  170  through chemical pressure sensors ( 30  if FIG.  1 ). If levels of chemicals are not dropping, a chemical output valve error is set and the system is shut down at step  172 . If levels are dropping, step  176  checks if the level of chemical in each of the pods has dropped by the requested amount. If sufficient drop of chemical level has not occurred, the system loops back to step  170 . If sufficient drop has occurred, the respective chemical output valve(s) is (are) closed at step  178 . Pod pressure is again checked for constant level at step  180 . If chemical level is changing, a chemical output valve error is set at step  182  and the system is shut down. If chemical level is constant, a determination is made as to whether all chemical requests for the requesting washer have been satisfied at step  184 . If all requests have not been satisfied, the system loops back to step  170 . If all requests have been satisfied, the output pump ( 36  in FIG. 1) continues to run for a preset time to post-flush the system piping at step  186  and the volumes of chemical(s) dispensed is (are) logged at step  188 . The system queries whether this is the last event for the requesting washer at step  190 . If yes, the end time is recorded at step  192  and the system recycles to start. If not, the system recycles at step  194  to start. 
     In order to maintain the desired proportions of chemicals, both for quality of results and for economy of use, the present invention provides a protocol by which calibration is accomplished. The calibration routine shown in FIG. 6 compensates for sensor and pump variations as well as for variations in the specific gravity of chemicals from batch to batch. The calibration routine starts at step  200 , with the output pump ( 36  in FIG. 1) started at step  202  and the first diverter valve ( 34  in FIG. 1) accessed at step  204  and the diverter opened at step  206 . The pressure sensor ( 38  of FIG. 1) value is stored in the controller at step  208  and the system determines whether this is the last diverter valve at step  212 . If not, the next diverter valve is accessed in step  210 . If the last diverter valve has been checked, chemical refill pumps ( 24  in FIG. 1) are disabled at step  214  and a first chemical output valve is opened at step  216  and the pod is emptied. The system determines that a pod is empty when the pressure sensed at the output pressure sensor drops, precipitously because no liquid chemical remains at chemical output valve  28  (FIG. 1) and air enters the pod through the vent hole in the top of pod  26 . The chemical output valve is closed and the pod pressure is recorded at step  218 . The determination of whether this is the last chemical pod is made at step  220 . If no, the system increments to the next pod at step  222  and loops back to step  216 . If yes and all pods are empty, the output pump is stopped in step  224  and the system goes to the first chemical refill pump, which is started in step  226 . The refill pump operates until the overflow switch ( 32  in FIG. 1) is activated in step  228 , the refill pump is stopped, and the pressure value is recorded. Whether this is the last chemical pod is determined at step  230 . If no, the system moves to the next pod in step  232  and loops back to step  226 . If yes, the pressure change per ounce, based on the volume of the pod and the pod empty and pod full pressure values, is calculated at step  240  for all pods and the calibration routine is stopped at step  242 . 
     Further to the capacity of the system to operate according to specifications is its ability to periodically verify that each of the critical components is operating, for which a self testing protocol is provided as shown in flowchart form in FIGS. 7A and 7B. The system is started at step  300  and a determination is made of whether the air pressure switch, for verification of air pressure needed for air-actuated pumps and values, is closed is made in step  302 . If no, the system is stopped and an error displayed in step  304 . If yes, a determination of whether the water pressure switch, for verification of water supply, is closed is made in step  306 . If no, the system is stopped and an error displayed in step  308 . If yes, the output pump ( 36  of FIG. 1) is started in step  310 , and a determination of whether the output pressure is within limits is made in step  312 . If no, the system is stopped and an error displayed in step  314 . If yes, the water tank refill valve is disabled in step  316 , and a determination of whether the water tank level is falling is made in step  318 . If no, the system is stopped and an error displayed in step  320 . If yes, the output pump is stopped and the water tank refill valve ( 20  of FIG. 1) is opened in step  322 . A determination of whether the water tank level is rising is made in step  324 . If no, the system is stopped and an error displayed in step  326 . If yes, the water tank refill valve automatic operation is reactivated and the system waits for the valve to close in step  328 . The system then determines whether the water tank level is constant in step  330 . If no, the system is stopped and an error displayed in step  332 . If yes, the output pump is started and the system moves to the first diverter valve ( 34   a  of FIG. 1) in step  334 , which is opened in step  336 . A determination as to whether the pressure is adequate is made in step  338 . If no, the system is stopped and an error displayed in step  340 . If yes, the first diverter valve is closed in step  342 , and the system determines whether this is the last diverter valve in step  344 . If no, the system moves to the next diverter valve in step  346  and returns to step  336 . If yes, the system moves to the first chemical output valve ( 28   a  in FIG. 1) in step  348  and opens the valve in step  350 . A determination is made whether the chemical pod ( 26  of FIG. 1) level is falling. If no, the system is stopped and an error displayed in step  356 . If yes, the chemical output valve is closed and the refill pump ( 24   a  of FIG. 1) is started in step  354 . A determination of whether the pod level is rising is made in step  358 . If no, the system is stopped and an error displayed in step  360 . If yes, the refill pump is stopped once the pod is full in step  362 . A determination is made of whether this is the last chemical pod in step  364 . If no, the system moves to the next chemical pod in step  366  and returns to step  350 . If yes, the output pump is stopped in step  368  and the test is terminated in step  370 . 
     The above detailed description of a preferred embodiment of the invention sets forth the best mode contemplated by the inventor for carrying out the invention at the time of filing this application and is provided by way of example and not as a limitation. Accordingly, various modifications and variations obvious to a person of ordinary skill in the art to which it pertains are deemed to lie within the scope and spirit of the invention as set forth in the following claims.