Method and system for controlling a drying process

Abstract

A dry cleaning device includes a cleaning enclosure suitable for receiving clothing articles and a cleaning fluid, typically a solvent based cleaning fluid, and circuitry coupled to the dry cleaning device for sensing at least one operational parameter of the dry cleaning device and for calculating a retained cleaning fluid content in the articles disposed within the cleaning enclosure based on the at least one operational parameter. Alternatively, the circuitry may calculate the amount of cleaning fluid returned to the system during the cleaning process.

Description

BACKGROUND

The invention relates generally to article cleaning apparatuses and more specifically to a method and system for controlling a drying process in a dry cleaning apparatus.

Solvent based article cleaning systems, better known as “dry cleaning” systems, typically include washing or rinsing systems and drying systems, for cleaning articles such as objects of clothing, drapes, upholstery or similar textiles. Before the articles may be reused after cleaning, they should be substantially devoid of the solvent based cleaning fluid. If the solvent is not substantially removed from the articles, the articles will feel oily to the touch and will require additional cleaning prior to use.

In addition, if the solvent is not substantially recovered after the dry cleaning process is completed, the solvent will need to be replaced more frequently, driving up the cost per usage by the consumer and potentially requiring an overall increase in the periodicity of cartridge or solvent replacement and servicing.

Currently, to achieve removal of the solvent, conventional systems typically employ a time-based drying cycle that may not accurately indicate the residual amount of the solvent based cleaning fluid in the articles.

Accordingly, development of improved systems and methods for controlling these drying cycles to ensure solvent recovery in dry cleaning systems is desired.

BRIEF DESCRIPTION

A dry cleaning device includes a cleaning enclosure suitable for receiving clothing articles and a cleaning fluid, typically a solvent based cleaning fluid, and circuitry coupled to the dry cleaning device for sensing at least one operational parameter of the dry cleaning device and for calculating a retained cleaning fluid content in the articles disposed within the cleaning enclosure based on the at least one operational parameter. Alternatively, the circuitry may calculate the amount of cleaning fluid returned to the system during the cleaning process.

DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic of a dry cleaning device according to an embodiment of the invention.

FIG. 2 is a graphical illustration of data collected that is related to one embodiment of the instant invention.

FIG. 3 is a graphical illustration of data collected that is related to another embodiment of the instant invention.

FIG. 4 is a graphical illustration of data collected that is related to another embodiment of the instant invention.

FIG. 5 is a flow chart that is representative of one method of operation associated with the instant invention.

DETAILED DESCRIPTION

A dry cleaning device 10 comprises a cleaning enclosure 12 suitable for receiving clothing articles (not shown) and a cleaning fluid, typically a solvent based cleaning fluid, introduced via an inlet line 14, as shown in FIG. 1. Additionally, dry cleaning device 10 further includes circuitry 16 coupled to the dry cleaning device 10 for sensing at least one operational parameter of the dry cleaning device 10 and for calculating a retained cleaning fluid content in the articles disposed within the cleaning enclosure based on at least one operational parameter.

As used herein, the term Retained Moisture Content (“RMC”) is defined as: (weight of the articles with moisture—dry weight of the articles)/(dry weight of articles).

As used herein, the term moisture refers to liquids retained in the clothes from the solvent, the water and any combination thereof.

As used herein, the term “articles” is defined, for illustrative purposes and without limitation, as fabrics, textiles, garments, and linens and any combination thereof.

As used herein, the term “solvent based cleaning fluid” is defined for illustrative purposes and without limitation, as comprising a cyclic siloxane solvent and, optionally, a cleaning agent. If water is present in a solvent based cleaning fluid, the water is typically present in an amount in a range from about 1 percent to about 8 percent of the total weight of the solvent based cleaning fluid. In another embodiment of the present invention, if water is present in the solvent based cleaning fluid, the water is typically present in an amount in a range from about 1 percent to about 2 percent of the total weight of the solvent based cleaning fluid. In one example, the cyclic siloxane solvent is decamethylcyclopentasiloxane (hereinafter referred to as D5).

As used herein, the term, “cleaning agent” is defined for illustrative purposes and without limitation, as being selected from the group consisting of sanitizing agents, emulsifiers, surfactants, detergents, bleaches, softeners, and combinations thereof.

As used herein, the term, “water based cleaning fluid” is defined for illustrative purposes and without limitation, as comprising water and, optionally, a cleaning agent.

As used herein, the term, “cleaning process” is defined, for illustrative purposes and without limitation, as utilizing a solvent cleaning process, water cleaning process, and any combination thereof.

The dry cleaning device 10 further comprises an air management system 18 and a fluid processing system 20 and a controller 22 that is coupled to the cleaning enclosure 12, the air management system 18, and the fluid processing system 20. The controller 22 is configured to perform a variety of cleaning processes. A cleaning process typically includes at least three main steps, a washing step, a spinning step and a drying step.

The cleaning enclosure 12 of FIG. 1 typically comprises a rotatable basket 24 coupled to a motor 26. The rotatable basket 24 has a plurality of holes 28. The motor 26 rotates the rotatable basket 24. The direct drive orientation of the rotatable basket 24 and the motor 26 is provided for illustrative purposes and it is not intended to imply a restriction to the present invention. While the cleaning enclosure 12 is shown comprising a rotatable basket 24 and an accompanying motor 26, other types of non-rotating cleaning enclosures are contemplated in this invention.

In accordance with one embodiment of the instant invention, upon introduction of articles within cleaning enclosure 12 and initiation of a cleaning process by a user via a user control interface (not shown), a solvent based cleaning fluid is introduced within the cleaning enclosure 12 and the controller 22 initiates a washing step of the cleaning process. The articles are typically agitated together with the solvent based cleaning fluid to clean the articles. After the washing cycle is completed, the solvent based cleaning fluid is drained to the fluid processing system 20. The draining of solvent based cleaning fluid typically recovers about 75%-90% of the solvent based cleaning fluid that was originally introduced. Most of the remaining solvent based cleaning fluid is retained within the articles.

Next, the articles are typically centrifuged in a spinning step in order to recover additional solvent based cleaning fluid. The spinning step typically recovers about an additional 5%-15% of the solvent based cleaning fluid bringing the total recovery to about 95% of the introduced amount.

Next, the articles are submitted to a drying step of the cleaning process. The articles are typically tumbled in cleaning enclosure 12 and dried using air management system 18. Hot, dry air is forced over the articles, heating the articles and the solvent based cleaning fluid and vaporizing the solvent based cleaning fluid. The vapor flows from the cleaning enclosure 12 to the air management system 18 where the vapor is condensed and the condensate is gravity fed back to the fluid processing system 20 via drain 36. The drying step of the cleaning process typically recovers about an additional 3% to 4.5% bringing the total recovered solvent based cleaning fluid to about 99.5% of the introduced amount.

As discussed above, because the solvent based cleaning solution is relatively expensive and the replacement involves the end-user replacing the solvent, typically via a cartridge insert, it is important to ensure that the recovered amount of the solvent based cleaning fluid is as close to 100% as reasonably possible. Currently, the appropriate controls are not available and most systems use an ineffective drying time approximation to determine the amount of residual solvent based cleaning fluid. This drying time approximation is not a robust technique and results in ineffective recovery of the cleaning fluid or alternatively, over-drying of the articles.

There are a variety of novel arrangements that can be utilized to ensure that the maximum quantity of the solvent based cleaning fluid is efficiently recovered after a cleaning process is completed, a number of which will be discussed below.

According to one embodiment of the instant invention, controller 22 is configured to sense operational parameters of the dry cleaning device 10, calculate the solvent based cleaning fluid content in the articles or alternatively the amount of the solvent based cleaning fluid returned to the fluid processing system 20, and based on that calculation, control the drying step of the dry cleaning device 10.

In general, the operational parameters relate to the operation of dry cleaning device 10, and the operational parameters may include, for example, cleaning fluid inflow or outflow rates, cleaning fluid vapor pressure inside the cleaning enclosure 12, airflow inflow or outflow rates, airflow inlet and outlet temperatures, various wash cycles (rinse, tumble, drying) times, basket rotation speeds, article weight, cleaning fluid weight and volume, among various others, and various such operational parameters that will occur to those skilled in the art. It is appreciated that drying process parameters (e.g. spin time, airflow temperatures, basket vapor pressure) form a subset of the operational parameters of dry cleaning device 10. The controller 22 is configured to receive and interpret a state of at least one of such operational parameters.

Controller 22 typically comprises a digital signal processor, configured to receive and execute instructions. The controller 22 may further comprise, or be associated with a data storage device (not shown in the figures) for storing various data including instructions and operational parameters. In one embodiment, the controller 22 includes simulation models for various operating cycles of the dry cleaning device 10. Controller 22 also comprises instructions for correlating an operational parameter of the dry cleaning device to the retained solvent based cleaning fluid content in the articles or the amount of solvent based cleaning fluid returned. Such correlation can be accomplished using many conventional techniques including, for example, using a lookup table or a plot.

In one embodiment of the instant invention, the dry cleaning device 10 includes at least one temperature sensor 110 coupled to the controller 22 and in communication with the air management system 18 such that the temperature sensor 110 senses the temperature of the airflow flowing between the air management system 18 and the cleaning enclosure 12 during the drying step of the cleaning process. According to one technique, an inlet temperature of the airflow entering into cleaning enclosure 12 is sensed, and the inlet temperature is correlated to the retained cleaning fluid content by controller 22. According to another technique, an outlet temperature of the airflow exiting the cleaning enclosure 12 is sensed, and the outlet temperature is correlated to the retained cleaning fluid content by controller 22. According to yet another technique, a difference between the outlet temperature and the inlet temperature of the airflow is calculated, and the difference is correlated to the retained cleaning fluid content by controller 22.

More specifically, and with respect to FIG. 2, the graphical display illustrates the relationship between an airflow inlet temperature, an airflow outlet temperature and the retained cleaning fluid content. FIG. 2 illustrates that the inlet and outlet temperatures converge as the retained cleaning fluid content decreases. It is also observed from FIG. 2 that the difference between the inlet and outlet temperatures decreases with decreasing retained cleaning fluid content. The rate of variation of the inlet or outlet temperatures, or the difference between the inlet and outlet temperatures, with respect to the retained cleaning fluid content may be empirically determined, and this data may then be used to correlate a current state of these parameters to ascertain a current state of the retained cleaning fluid content in articles, during the drying process by controller 22.

In another embodiment of the instant invention, the dry cleaning device 10 (FIG. 1) includes at least one pressure sensor 120, typically a gas specific vapor pressure sensor, coupled to the controller 22 and disposed adjacent to the enclosure 12 such that pressure sensor 120 is positioned to sense the vapor pressure within cleaning enclosure 12 during the drying step of the cleaning process. The vapor pressure of the cleaning fluid inside the cleaning enclosure 12 is sensed by pressure sensor 120 and correlated by controller 22 to the retained cleaning fluid content. As shown in FIG. 3, the vapor pressure is nearly constant during a portion of the drying process and begins to gradually drop off until finally stabilizing. Using either the empirical data surrounding the stabilization or the rate of change of the vapor pressure, the retained cleaning fluid content can be calculated. In fact, in FIG. 3, it can be seen that the rate of change of the vapor pressure undergoes a slope change right in the region of the 1% RMC location. It is further illustrated in FIG.3 that the final vapor pressure measurement is not constant and is highly dependent on the type of fabrics being washed. The vapor pressure measurements or the calculated rate of change may also be combined with a change over time calculation or a model or both to calibrate and improve the accuracy of the RMC calculation. As discussed above, the vapor pressure can be directly measured by pressure sensor 120 or may be inferred based on certain measurements from pressure sensor 120, for example inferring vapor pressure from infrared measurements.

In another embodiment of the invention, the dry cleaning device 10 (FIG.1) includes at least one torque load sensor 130 coupled to the controller 22 and disposed adjacent the rotatable basket 24 to sense the torque load measurement on the motor 26 during the cleaning process. One implementation of this embodiment may include rotating the basket at a known rotational velocity after the introduction of articles and prior to introduction of the cleaning fluid to establish a baseline torque load. This technique utilizes the fact that the motor 26, having a known torque curve, requires a specific motor torque to tumble articles and this required torque increases as the weight of the articles increase. With an amount of cleaning fluid being retained in the articles, the article weight increases from a dry state of the articles, and correspondingly the torque required to rotate these articles is higher. This increase in the torque load is therefore indicative of the excess weight in the articles due to the cleaning fluid, and accordingly the torque load required to rotate the motor 26 is correlated by controller 22 to the retained cleaning fluid content.

In another embodiment of the invention, the dry cleaning device 10 includes at least one weight sensor 140 coupled to the controller 22 and to the fluid processing system 20 to sense the weight of the returned cleaning fluid during the cleaning process. Since the beginning weight of the cleaning fluid is a known value, the controller 22 would control the drying process to ensure that a certain predetermined weight of cleaning fluid is returned before ending the cleaning process. In one embodiment, for example, the predetermined weight is in the range between about 99.1 percent of the initial weight of the cleaning fluid to about 99.9 percent of the initial weight of the cleaning fluid. In another embodiment, for example, the predetermined weight is in the range between about 99.3 percent of the initial weight of the cleaning fluid to about 99.7 percent of the initial weight of the cleaning fluid.

In another embodiment of the invention, the dry cleaning device 10 includes at least one volume sensor 150 coupled to the controller 22 and to the fluid processing system 20 to sense the volume of the returned cleaning fluid during the cleaning process. Since the beginning volume of the cleaning fluid is a known value, the controller 22 would control the drying process to ensure that a certain predetermined volume of cleaning fluid is returned before ending the cleaning process. In one embodiment, for example, the predetermined volume is in the range between about 99.1 percent of the initial volume of the cleaning fluid to about 99.9 percent of the initial volume of the cleaning fluid. In another embodiment, for example, the predetermined volume is in the range between about 99.3 percent of the initial volume of the cleaning fluid to about 99.7 percent of the initial volume of the cleaning fluid.

Another method to ensure recovery of a significant percentage of the cleaning fluid is to embed a calibrated model of the drying process within controller 22 to predict RMC based on the physics of the drying process. Such a model would utilize the airflow temperatures flowing into and out of the air management system 18, as well as the airflow based on a fixed value and pressure drop model of the dry cleaning system 10. From these known or calculated values, the vapor pressure and RMC can be predicted. The RMC can be predicted quite accurately as shown in the FIG. 4 below for six runs with different starting RMC values. This accuracy holds not only for the constant rate portion of the drying cycle, but also for the tail end, where the drying rate is much lower and the final RMC is much closer to the preferred value (typically between 0% and 1%).

An additional measure to ensure recovery of cleaning solution is to lock the system user out of the cleaning enclosure 12 until the RFC calculated by controller 22 is less than a predetermined value, for example, 0.5%.

FIG. 5 illustrates, with the help of a flow diagram, a specific method for controlling the drying process, according to one embodiment of the invention. The drying process is started SI in the cleaning enclosure 12, and at least one operational parameter is sensed S2. Based on the sensed operational parameter, a value of the retained cleaning fluid content in the articles or the amount of cleaning fluid returned is calculated S3. An ascertainment S4 is made, of whether the condition of the retained cleaning fluid content is less than a predetermined value, or the amount of returned cleaning fluid is more than a predetermined value, is met. If the condition is not met, the drying process is continued. If the condition is met, however, the drying process is stopped.

While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

1. A dry cleaning device, comprising: a cleaning enclosure configured to receive articles and a cleaning fluid; and circuitry coupled to said dry cleaning device for sensing at least one operational parameter of said dry cleaning device and calculating a retained cleaning fluid content in said articles based on said at least one operational parameter.

2. A dry cleaning device according to claim 1, wherein said circuitry controls a drying process for said dry cleaning device based on the calculated retained cleaning fluid content.

3. A dry cleaning device according to claim 1, wherein said circuitry includes at least one sensing device.

4. A dry cleaning device according to claim 3, wherein said at least one sensing device is a temperature sensor.

5. A dry cleaning device according to claim 4, further comprising an air management system for circulating an airflow through said cleaning enclosure and wherein said temperature sensor senses a temperature of said airflow and said circuitry calculates the retained cleaning fluid content based on said sensed temperature.

6. A dry cleaning device according to claim 3, wherein said at least one sensing device is a vapor pressure sensor to sense a vapor pressure of the cleaning fluid in the cleaning enclosure and said circuitry calculates the retained cleaning fluid content based on said sensed vapor pressure.

7. A dry cleaning device according to claim 3, wherein said cleaning enclosure includes a rotatable basket and said at least one sensing device is a torque load sensor to sense a torque load measurement while said basket rotates with said articles at a known speed and said circuitry calculates the retained cleaning fluid content based on said sensed torque load measurement.

8. A dry cleaning device according to claim 3, further comprising a fluid processing system configured to receive the cleaning fluid after usage within the cleaning enclosure, wherein said at least one sensing device is a weight sensor adapted to sense the weight of said cleaning fluid within said fluid processing system and said circuitry calculates the retained cleaning fluid content based on said sensed weight measurement.

9. A dry cleaning device according to claim 3, further comprising a fluid processing system configured to receive the cleaning fluid after usage within the cleaning enclosure, wherein said at least one sensing device is a volume sensor adapted to sense the volume of said cleaning fluid within said fluid processing system and said circuitry calculates the retained cleaning fluid content based on said volume measurement.

10. A dry cleaning device according to claim 1, wherein said circuitry is configured to provide a calibrated model that is representative of a drying process and said circuitry calculates the retained cleaning fluid content based on said model in conjuction with said sensed operational parameters.

11. A method for controlling a drying process in a dry cleaning device that uses a cleaning fluid to clean articles, the method comprising: sensing at least one operational parameter of the dry cleaning device; calculating a retained cleaning fluid content in the articles based on the sensed operational parameter; and controlling the drying process based on the calculated retained cleaning fluid content.

12. A dry cleaning device for cleaning articles with a solvent based cleaning fluid, comprising: a cleaning enclosure configured to receive the articles; a fluid processing system that supplies a solvent based cleaning fluid to the cleaning enclosure; an air management system that supplies an airflow to the cleaning enclosure; at least one sensing device configured to sense an operational parameter of the dry cleaning device; and a controller responsive to the at least one sensing device, wherein the controller is configured to calculate the retained solvent based cleaning fluid content in the articles based on the sensed operational parameter and control the drying process based on the calculated retained cleaning fluid.

13. A dry cleaning device for cleaning articles with a solvent based cleaning fluid, comprising: a means for receiving articles; a means for introducing said solvent based cleaning fluid into said means for receiving articles upon introduction of said articles; a means for determining at least one operational parameter of said dry cleaning device; and and a means for calculating a retained solvent based cleaning fluid content in said articles based on said at least one operational parameter.

14. A dry cleaning device for cleaning articles with a solvent based cleaning fluid in accordance with claim 13, further comprising means for controlling a drying process for said dry cleaning device based on the calculated retained solvent based cleaning fluid content.

15. A dry cleaning device for cleaning articles with a solvent based cleaning fluid, comprising: a cleaning enclosure configured to receive the articles; a fluid processing system that supplies a solvent based cleaning fluid to the cleaning enclosure; an air management system that supplies an airflow to the cleaning enclosure; at least one sensing device configured to sense an operational parameter of the dry cleaning device; and a controller responsive to the at least one sensing device, wherein the controller is configured to calculate the amount of returned solvent based cleaning solution based on the sensed operational parameter and control the drying process based on the calculated returned cleaning fluid.

16. A dry cleaning device in accordance with claim 1, wherein said circuitry locks the cleaning enclosure until the calculated retained fluid content is less than a predetermined value.