Machine for anticipatory sensing and intervention to avoid swimmer entrapment

Abstract

A machine for anticipatory sensing and intervention to avoid swimmer entrapment, with an active pre-entrapment sensor (e.g. ultrasonic) that assesses the relative hazard based on swimmer proximity to the drain cover. An Ultrasonic Transducer launches waves into the suction piping and/or drain system, and to receive echoes from the drain cover, swimmer limbs, hair or body, and the water surface parellel to the drain cover. A Transmitter/Pulser electrically energizes the ultrasonic transducer to launch waves into the suction piping and/or drain system, A Receiver/Processor detects the echoes electrical signals from the the ultrasonic transducer and to receive echoes from objects of interest beyond the pool drain. A Logic and Control element converts the detected signals into reliable information regarding a swimmer safety/hazard status. An Output provides a pump shutdown command when required. Solutions for both new construction and retrofit are described.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on provisional application Ser. No. 60/549514, filed on Mar. 2, 2004 and provisional application Ser. No. 60/587367, filed on Jul. 13, 2004.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

DESCRIPTION OF ATTACHED APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

This invention relates generally to the field of Swimmer Entrapment Avoidance and more specifically to a machine for anticipatory sensing and intervention to avoid swimmer entrapment.

Entrapment comprises all of the hazards of evisceration, hair entanglement, limb entrapment, body entrapment, etc.

To provide a means of detecting the required presence of the drain cover, the absence of which creates a lethal hazard. A missing drain cover requires immediate pump shutdown and no existing SVRS system can detect this situation.

To provide a means of anticipating a potential swimmer entrapment situation as at a swimming pool or spa drain.

The present invention utilizes an active sensor technology that allows anticipatory sensing and intervention before hazardous drain contact can occur.

The Consumer Product Safety Commission (CPSC) has reported over many years that there are dozens of deaths and grave injuries each year in the US, mostly young children, due to the suction entrapment hazards of swimming pools, wading pools and spas. The CPSC has recently set up testing facilities for Safety Vacuum Release Systems (SVRS), products now on the market intended to rapidly reduce suction and release an entrapped person. The potential and actual hazards due to underwater suction drains include disembowelment (which can occur in a fraction of a second), hair entanglement, and limb or body entrapment. All SVRS devices now sense an increase in suction, near the pump inlet, that occurs when a person blocks all or a major part of a remote suction drain. None can anticipate the event, and that is a serious flaw in swimmer protection.

In addition to the tragic results mentioned there are large societal costs related to long term medical treatment of the injured, major awards and expenses of litigation, inhibiting business activity, and reducing opportunity for the public to enjoy the fitness, health and recreation benefits of safe water facilities whether public or private.

This invention can deal with new construction as well as retrofit, but the overwhelming market for industry lies in the estimated 15 million or more old swimming pools that can not feasibly be retrofitted with prior technology. Moreover, it is precisely these old pools that are the most hazardous because they do not have the other safety features such as anti-entrapment, anti-entanglement drain covers, dual main drains, vents, or SVRS devices that are now increasingly found on new pools. Old pools may also have been upgraded with higher power pumps that present a stronger suction hazard. Present SVRS also have a major weakness in terms of field reliability over years of time with no requirements for periodic testing and traceability of such tests. In addition, the proposed solution may also be useful for new construction as well.

The object of this invention is to provide swimmer protection wherein the occurrence of a potentially or actually hazardous approach to a drain is measured and can be acted upon prior to any contact or entrapment occurring. FIG. 1 depicts a typical situation.

The objective is to use the pool suction piping network as a sonic/ultrasonic waveguide. If a sonic pulse wave is launched into the suction piping network from a point above ground, near the pump inlet, propagates through the suction piping network to the underwater plastic drain cover(s) (they may be augmented) and provides a unique return echo so that we can be assured that the drain cover is in place. This is a major benefit because missing drain covers have produced horrendous permanent injuries and drownings.

Futhermore, the sonic pulse wave will also pass thru the cover, and/or its holes for the passage of water, and detect the pool water/air interface which is a strong reflector. This allows for a self-testing and self-calibrating sensor system. In addition, a swimmer approaching a drain can be sensed directly and/or indirectly by means of simple range gating since the geometry is fixed for any given existing pool. The following figure depicts a situation where the transducer is co-located with a drain, but the principle is equally applicable for a transducer located far from the drain by means of a low loss sonic/ultrasonic waveguide.

Another benefit of an active sonic sensor is the potential to measure the water velocity in the suction piping via doppler processing. Excessive water velocity is indicative of issues such as a replacement pump of higher horsepower than is safe for the original installation.

Also, as in FIG. 1, sensing of excessively high or low pool water level will also be feasible.

Ultrasonics is a rapidly advancing technology with a high degree of new knowledge and understandings with many new applications. The literature is replete with examples of rapid variations of attenuation with frequency for certain modes of propagation. U.S. Pat. No. 5,289,436 Ultrasonic waveguide, J. H. Terhune offers some interesting examples of low loss frequency windows in thin tubular structures. Such frequency windows are exploited in the present invention.

The state of the art in piping networks is based on steel piping over medium to long spans where the object is to detect flaws (e.g corrosion) from a distance because the piping is inaccessable. That technique has proven sucessful and is commercialized.

This invention addresses plastic piping, and specifically PVC piping and standard PVC fittings because that is what is to be found in the vast majority of existing swimming pools. And, of course, the piping lies underground and sometimes under the pool structure which is most often poured concrete. New pool construction has fewer constraints on material choices and access for optimization is available. The research leading to this invention has shown useful, low loss, windows in the frequency domain that allow the application to be realized commercially.

All SVRS devices now sense an increase in suction, near the pump inlet, that occurs when a person blocks all or a major part of a remote suction drain. None can anticipate the event, and that is a serious flaw in swimmer protection.

FIELD OF THE INVENTION

The present invention relates generally to entrapment avoidance sensors and more specifically it relates to a anti-evisceration/entanglement/entrapment sensor system for a solution to the suction drain entrapment and entanglement hazard found in most swimming pools, spas and hot tubs. When a pool drain cover is damaged or missing a major hazard for limb or body entrapment, and even evisceration, exists. The ability of this invention to sense a missing drain cover is unique and can be used to shutdown the circulation system and generate alarms. The capability for short range swimmer detection is unique and extremely valuable because prevention of entrapment has been shown to be much safer than release of entrapment after it occurs. This is particularly true for situations leading to evisceration or hair entanglement.

Several Existing Patents Cover SVRS and Related Devices:

Recently, a few single purpose suction safety devices have been brought to market. A few single purpose pump suction sensor and shut-down devices and systems have also been brought to market such as: Stingl Switch, 6,059,536, Stingl, May 9, 2000; and Influent Blockage Detection System, U.S. Pat. No. 6,342,841, January 2002, Stingl; and Fluid Vacuum Safety Device for Fluid Transfer Systems in Swimming Pools, 5,947,700, September 1999, McKain et al; and Spa Pressure Sensing System Capable of Entrapment Detection, U.S. 6,227,808, May 2001, McDonough.

Several other patents describe very specific capability for a single purpose using novel sensors. For example: Pump Shutoff System, 6,039,543, March 2000, Littleton; describes a flow switch and control circuit to shut-down a pump when there is insufficient fluid flow and pump damage may result. Also, Pool Pump Controller, 5,725,359, March 1998, Dongo et al; does address swimmer safety regarding suction entrapment in a pool drain, by means of a novel diaphragm switch that removes power from the pool pump when a certain change in fluid pressure (unspecified) occurs.

Deficiency in Prior Technology

Some other prior art deficiencies may be summarized by the following:

• • A few specialized pump suction sensor switches e.g. Stingl Switch, 6,059,536, Stingl, May 9, 2000, and Influent Blockage Detection System, U.S. Pat. No. 6,342,841, January 2002, Stingl. These are expensive single purpose devices marketed primarily to municipal and large club pools. The MIMPSC, U.S. Pat. No. 6,676,831, however, is intended primarily for residential pools and spas where cost is a significant factor. If certain cost targets and multi functionality cannot be provided, most residential pools will continue to be unprotected, with concomitant risks to users and equipment.

Suction safety requires fast, sure removal of the entrapment force, severely limiting both the magnitude and duration of that force. Hair entanglement hazards are possibly quite sensitive to the duration of the suction force as well. Stingl, U.S. Pat. No. 6,342,841 asserts “there is no need to “relieve” residual vacuum in the line because water is not compressible”. The MIMPSC invention asserts, however, that there is a very significant increase in the total impulse (force×time) causing entrapment of a person. Recent data from an actual pool installation with the present invention showed a small increase in peak force of 12.3%, but accompanied by a large increase in the action time. The total time of significant entrapment force, as measured from the beginning of a measured rise in suction to when the shut-down returned suction to its beginning level was:

With suction dump valve: 0.417 seconds
Without suction dump:    1.503 seconds

This is a ratio of 3.6 to 1. Multiplying the force and time ratios we find that the overall entrapment impulse is four times greater if we do not “relieve” the suction with a vent to atmospheric pressure. The explanation for this situation may be related to the fact that the suction water column and pump impeller momentum does not instantly disappear when power is shutoff, but dissipates over a time period of 1.5 seconds. In the above discussion, just as in the cited patent, the measured suction was at or near the pump inlet port. Furthermore, if we examine the ratio of entrapment or entanglement time starting from when the pump is shutoff we find that:

Time from Shutoff to Atmospheric Pressure:

	With Suction Dump Valve:	0.08	seconds
	Without Suction Dump:	approximately 4	seconds

This is considered to be reason enough to include suction relief by using a properly configured dump valve. The cited patent also describes a “safe level of vacuum as 11 in.Hg.”. This level of vacuum is considered too high by several authorities, especially if prolonged action time is involved. The MIMPSC invention also accounts for the minor variations present in pools with in floor cleaning systems and solar heating, but typically operates at a shut-down threshold of 8 in.Hg.

Another patent, 5,947,700, September 1999, McKain et al, describes an alternative embodiment of a suction entrapment release device, and mentions that the “ideal vacuum pressure at which the frangible member disintegrates is approximately 20 in. Hg.” This value is considered extraordinarily high as a safe limit. In fact, it is questionable as to whether it could be achieved at the location shown, near the input to the pump, because of the presence of the second suction line from the pool.

The main problem with conventional entrapment avoidance sensors are that they are constrained to allow a significant increase in the suction hazard before taking corrective action. This allows a potential victim to approach the drain closely without a significant increase in the suction being sensed. Only when the suction port is mostly blocked by the victims body or limb does a large increase in suction suddenly occur. Under these conditions a small child may be partially or totally eviscerated in an extremely short period of time. Some tests reported in the literature indicate that damage can be done within a small fraction of a second, when the short distance to complete the drain sealing is covered and a very high degree of vacuum is thereby allowed to occur momentarily. Another problem with conventional entrapment avoidance sensors are that they cannot anticipate the dangerous level of suction which will occur with full drain blockage until it occurs. The subject invention directly senses and measures the approach of a person or other object to the drain before significant blockage can occur. This anticipation by the subject invention is due to sensing distance from the drain rather than the consequence of a blocked drain. Another problem with conventional entrapment avoidance sensors are that they cannot detect the missing drain cover. When a drain cover is missing the stage is set for limb entrapment leading to drowning or as in several cases a lifelong mental disability due to prolonged oxygen starvation. Only an active sensor operating at close range from within the drain system can easily and surely detect and prevent all five major forms of drain entrapment as defined in ASME A112.19.17-2002, ASTM PS 10-03, and NSPI X(in work).

While these devices may be suitable for the particular purpose which they address, they are not as suitable for a solution to the suction drain entrapment and entanglement hazard found in most swimming pools, spas and hot tubs. When a pool drain cover is damaged or missing a major hazard for limb or body entrapment, and even evisceration, exists. The ability of this invention to sense a missing drain cover is unique and can be used to shutdown the circulation system and generate alarms. The capability for short range swimmer detection is unique and extremely valuable because prevention of entrapment has been shown to be much safer than release of entrapment after it occurs. This is particularly true for situations leading to evisceration or hair entanglement. The main problem with conventional entrapment avoidance sensors are that they are constrained to allow a significant increase in the suction hazard before taking corrective action. This allows a potential victim to approach the drain closely without a significant increase in the suction being sensed. Only when the suction port is mostly blocked by the victims body or limb does a large increase in suction suddenly occur. Under these conditions a small child may be partially or totally eviscerated in an extremely short period of time. Some tests reported in the literature indicate that damage can be done within a small fraction of a second, when the short distance to complete the drain sealing is covered and a very high degree of vacuum is thereby allowed to occur momentarily. Another problem is that they cannot anticipate the dangerous level of suction which will occur with full drain blockage until it occurs. The subject invention directly senses and measures the approach of a person or other object to the drain before significant blockage can occur. This anticipation by the subject invention is due to sensing distance from the drain rather than the consequence of a blocked drain. Also, another problem is that they cannot detect the missing drain cover. When a drain cover is missing the stage is set for limb entrapment leading to drowning or as in several cases a lifelong mental disability due to prolonged oxygen starvation. Only an active sensor operating at close range from within the drain system can easily and surely detect and prevent all five major forms of drain entrapment as defined in ASME A112.19.17-2002, ASTM PS 10-03, and NSPI X(in work).

In these respects, the anti-evisceration/entanglement/entrapment sensor system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of a solution to the suction drain entrapment and entanglement hazard found in most swimming pools, spas and hot tubs. When a pool drain cover is damaged or missing a major hazard for limb or body entrapment, and even evisceration, exists. The ability of this invention to sense a missing drain cover is unique and can be used to shutdown the circulation system and generate alarms. The capability for short range swimmer detection is unique and extremely valuable because prevention of entrapment has been shown to be much safer than release of entrapment after it occurs. This is particularly true for situations leading to evisceration or hair entanglement.

All SVRS devices now sense an increase in suction, near the pump inlet, that occurs when a person blocks all or a major part of a remote suction drain. None can anticipate the event, and that is a serious flaw in swimmer protection.

This invention can deal with new construction as well as retrofit, but the overwhelming market for industry lies in the estimated 15 million or more old swimming pools that can not feasibly be retrofitted with present technology. Moreover, it is precisely these old pools that are the most hazardous because they do not have the other safety features such as anti-entrapment, anti-entanglement drain covers, dual main drains, vents, or SVRS devices that are now increasingly found on new pools. Old pools may also have been upgraded with higher power pumps that present a stronger suction hazard. Present SVRS also have a major weakness in terms of field reliability over years of time with no requirements for periodic testing and traceability of such tests. In addition, the proposed solution may also be useful for new construction as well.

With the present invention we can be assured that the drain cover is in place. This is a major benefit because missing drain covers have produced horrendous permanent injuries and drownings.

The present invention relates generally to entrapment avoidance sensors and more specifically it relates to a anti-evisceration/entanglement/entrapment sensor system for a solution to the suction drain entrapment and entanglement hazard found in most swimming pools, spas and hot tubs. When a pool drain cover is damaged or missing a major hazard for limb or body entrapment, and even evisceration, exists. The ability of this invention to sense a missing drain cover is unique and can be used to shutdown the circulation system and generate alarms. The capability for short range swimmer detection is unique and extremely valuable because prevention of entrapment has been shown to be much safer than release of entrapment after it occurs. This is particularly true for situations leading to evisceration or hair entanglement.

The main problem with conventional entrapment avoidance sensors are that they are constrained to allow a significant increase in the suction hazard before taking corrective action. This allows a potential victim to approach the drain closely without a significant increase in the suction being sensed. Only when the suction port is mostly blocked by the victims body or limb does a large increase in suction suddenly occur. Under these conditions a small child may be partially or totally eviscerated in an extremely short period of time. Some tests reported in the literature indicate that damage can be done within a small fraction of a second, when the short distance to complete the drain sealing is covered and a very high degree of vacuum is thereby allowed to occur momentarily.

Another problem with conventional entrapment avoidance sensors are that they cannot anticipate the dangerous level of suction which will occur with full drain blockage until it occurs. The subject invention directly senses and measures the approach of a person or other object to the drain before significant blockage can occur. This anticipation by the subject invention is due to sensing distance from the drain rather than the consequence of a blocked drain. Another problem with conventional entrapment avoidance sensors are that they cannot detect the missing drain cover. When a drain cover is missing the stage is set for limb entrapment leading to drowning or as in several cases a lifelong mental disability due to prolonged oxygen starvation. Only an active sensor operating at close range from within the drain system can easily and surely detect and prevent all five major forms of drain entrapment as defined in ASME A112.19.17-2002, ASTM PS 10-03, and NSPI X(in work).

In these respects, the anti-evisceration/entanglement/entrapment sensor system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of a solution to the suction drain entrapment and entanglement hazard found in most swimming pools, spas and hot tubs. When a pool drain cover is damaged or missing a major hazard for limb or body entrapment, and even evisceration, exists. The ability of this invention to sense a missing drain cover is unique and can be used to shutdown the circulation system and generate alarms. The capability for short range swimmer detection is unique and extremely valuable because prevention of entrapment has been shown to be much safer than release of entrapment after it occurs. This is particularly true for situations leading to evisceration or hair entanglement.

BRIEF SUMMARY OF THE INVENTION

The primary object of the invention is to prevent Entrapment which comprises all of the hazards of evisceration, hair entanglement, limb entrapment, body entrapment, etc.

Another object of the invention is to provide a means of detecting the required presence of the drain cover, the absence of which creates a lethal hazard. A missing drain cover requires immediate pump shutdown and no existing SVRS system can detect this situation.

Another object of the invention is to provide a means of anticipating a potential swimmer entrapment situation as at a swimming pool or spa drain.

A further object of the invention is anticipate a potential entrapment. Present Safety Vacuum Release Systems (SVRS) can do nothing to anticipate an entrapment until physical contact is made with the drain or drain cover and a significant increase in suction is sensed.

Yet another object of the invention is to avoid the risk of evisceration which is an extremely rapid process, as is hair entanglement, and the damage is done before present SVRS devices can react to the hazard.

Still yet another object of the invention is to utilize an active sensor technology that allows anticipatory sensing and intervention before hazardous drain contact can occur.

Another object of the invention is to detect masking of the water surface echo by any absorbtive object that may also be treated as an alarm situation.

Another object of the invention is to provide solutions for the two categories of need for the present invention: New pool/spa construction, and retrofit for old, existing, pool/spas.

A further object of the invention is that the optimum sensors may be different for each category because in new construction there are fewer constraints on operating frequency, transmitter power and receiver sensitivity, which control object detection, resolution and maximum range.

Yet another object of the invention is, for new construction, to optimize the suction piping network by eliminating the attenuative 90 degree elbows, using larger bend radius sweep elbows.

Still yet another object of the invention is, for new construction, locating a sensor in or under/behind each drain and the beams are easily directed perpendicular to the drain cover and beyond to the swimming area. Thus, the presense of an approaching swimmer can be detected, and tracked, to allow the pump to be shutdown prior to a dangerous physical contact.

Another object of the invention is, for existing pools, retrofitting drains and thus different frequencies and modes can be considered for propagation through the suction piping network.

Another object of the invention is a flow rate sensor. Flow is a significant parameter in the design of swimming pools and is not usually verified in the field. The sensor system can be enhanced to measure the doppler shift or Time of Flight, and thus provide a good estimate of water speed in the piping. The ANSI/ASME standards for water velocity are established to insure that the velocity is low enough to limit the magnitude of the suction hazard, and high enough for an economical pump and piping design. Additionally, low water velocity may be a symptom of a partially blocked drain or filter and can be used to alert service personnel.

A further object of the invention is the further benefit of a pool alarm, for example if a child falls into the pool, it is possible to detect this by various sensor modifications and/or extensions.

Yet another object of the invention is to provide an innovative design that is also self testing and self calibrating, unlike any other SVRS.

Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

In accordance with a preferred embodiment of the invention, there is disclosed a machine for anticipatory sensing and intervention to avoid swimmer entrapment, comprising: An active suction entrapment sensor (e.g. ultrasonic) that can assess the relative hazard based on swimmer proximity to the drain cover, An Ultrasonic Transducer, one or more, to launch waves into the suction piping and/or drain system, and to receive echoes from the drain cover, swimmer limbs, hair or body, and the water surface above the drain, A Transmitter/Pulser to electrically energize said ultrasonic transducer to launch waves into the suction piping and/or drain system, A Receiver/Processor to detect the echoes electrical signals from the said ultrasonic transducer, and to receive echoes from objects of interest beyond the pool drain, including but not limited to, the drain cover, a swimmer's body or limb in close proximity to the drain and/or cover, and the pool water surface, A Logic and Control element to convert the detected signals into reliable information regarding a swimmer safety/hazard status., An Output to provide a pump shutdown command if a close approach by a swimmer near a drain is measured, A housing for the Transmitter and Receiver, Logic and Control that can be located in the pool equipment area, near the pump inlet piping. A transducer mounting and interface adjacent to the pump inlet suction piping for retrofit applications. The transducer and its interconnecting cable may be mounted in or under the drain for new construction, or the same as for retrofit if suitable, and for new construction, and in some cases for retrofit, other suction side piping and fittings that optimize performance may be used instead of the Schedule 40 90 degree elbow that has been the standard for some time.

In accordance with a preferred embodiment of the invention, there is disclosed a process for anticipatory sensing and intervention to avoid swimmer entrapment, comprising the steps of: An active suction entrapment sensor (e.g. ultrasonic) that can assess the relative hazard based on swimmer proximity to the drain cover, An Ultrasonic Transducer, one or more, to launch waves into the suction piping and/or drain system, and to receive echoes from the drain cover, swimmer limbs, hair or body, and the water surface above the drain, A Transmitter/Pulser to electrically energize said ultrasonic transducer to launch waves into the suction piping and/or drain system. A Receiver/Processor to detect the echoes electrical signals from the said ultrasonic transducer, and to receive echoes from objects of interest beyond the pool drain, including but not limited to, the drain cover, a swimmer's body or limb in close proximity to the drain and/or cover, and the pool water surface, A Logic and Control element to convert the detected signals into reliable information regarding a swimmer safety/hazard status. An Output to provide a pump shutdown command if a close approach by a swimmer near a drain is measured, A housing for the Transmitter and Receiver, Logic and Control that can be located in the pool equipment area, near the pump inlet piping. A transducer mounting and interface adjacent to the pump inlet suction piping for retrofit applications. The transducer and its interconnecting cable may be mounted in or under the drain for new construction, or the same as for retrofit if suitable, and for new construction, and in some cases for retrofit, other suction side piping and fittings that optimize performance may be used instead of the Schedule 40 90 degree elbow that has been the standard for some time. PVC piping will be used but as we are dealing with suction side pressures the use of Schedule 40 pipe should not be a necessary limitation.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.

FIG. 1A is a Pool Shell Section with Swimmer and Drain

FIG. 1B is a Swim By Time History

FIG. 1C shows Swimmer Drain Approach Trajectories

FIG. 1D depicts Range Cells to Catagorize the Hazard Status

FIG. 2 A,B,C Alternate Ultrasonic Transducer Feeds

FIG. 3 Preferred New Construction Drain Detail

FIG. 4 A,B Block Diagrams for Remote Transducer/Launcher

FIG. 5 Detail of Preferred Retrofit Modification

FIG. 6 Detail of Replaceable Transducer for Retrofit

FIG. 7 A,B,C Propagation Test Data for Drain Cover and Hand

FIG. 8A Drain Cover and Hand in NO-GO gate

FIG. 8B Sweep Elbow Test Data

FIG. 8C U Tube Water Echo at 200 kHz

FIG. 9 Simplified Propagation Model

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner.

FIG. 1A shows the pool 10 containing water 11 a drain 16 a drain cover 14 and a suction pipe 12 that leads to the pump inlet (not shown here). Also a swimmer 18 encounters the sensor waves 19 emitted through the drain cover 14. Reflection echoes 20 are produced by the swimmer 18 and the water level 11.

FIG. 1B is an analysis of the range from the drain verus time as a swimmer passes by. shown are the range gates considered as safe “OK” and unsafe “No-Go”.

FIG. 1C emphasizes the rate of approach to a drain by a swimmer, and therefore a transition from safe to unsafe.

FIG. 1D defines several additional range cells or gates, so that logical decisions can be implemented to protect swimmers while minimizing the false alarm rate.

FIG. 2A is a detail of a drain 16 and feed pipe 12 that is acting as a waveguide for the ultrasonic waves 15 generated remotely. Likewise the echoes returned 17 are transferred to the remote transducer. This represents the preferred embodiment but in some retrofit installations it may not perform optimally. In this situation alternatives shown in FIGS. 2B and 2C would allow a transducer 30 to connect via a cable 32 or a launcher 28 to connect via a thin plastic tube ultrasonic waveguide 26.

FIG. 3 is a detail of the preferred embodiment for new construction. The drain 16 is used as a housing for the transducer or launcher 17, where the thansducer or launcher may be installed within the drain 16 on top of the bottom surface 19, or underneath the bottom 19 so that the transducer 17 need not be continuously immersed, If the transducer 17 is external to the drain bottom 19 it must be acoustically bonde to radiate perpendicularly to the bottom 19 and send waves through the cover to the water beyond. A conduit 21 houses and protects the feed cable or thin plastic waveguide 20 to the aboveground Transmit/Receive unit 22. Such an arrangement provides the most options for frequency and minimizes the attenuation problem, that occurs at higher frequencies, (See FIG. 9) thus offering the best Small Target Detectability that is available.

FIG. 4A is a block diagram for the use of a remote transducer with a cable feed. The transducer 17T is connected via cable 20C to the T/R unit 22 which is then connected to the Logic and Control unit 35. In normal operation, the L/C 35 sends an OK signal to the Alarms and Indicator 40 and a Green light will be displayed for the system status. When a Pump Shutdown is deemed necessary the UC unit 35 interrupts the Pump Cpntrol Signal 37, disconnecting the Pump from Power Source 38. Then the L/C unit 35 sends a No-Go signal to the A/I unit 40, the status light changes from green to red, and various alarms are sounded both locally and, if desired, remotely.

FIG. 4B is the same as 4A with the change of location for the transducer 17T and the addition of a Launcher 17L and waveguide 20WG.

FIG. 5A shows the physical arrangement of a typical pump and inlet side piping 53 and elbow fitting 54 leading to the underground pool drain, before modification.

FIG. 5B shows the preferred modification for retrofir applications wherin the suction side piping 53 is used a a waveguide for the ultrasonic pulses transmitted 57 and the echoes received 58. The transducer housing 55 connects to the Transmitter/Receiver unit 22 via cable 20C. The main modification is seen to involve removing the 90 degree elbow 54 and reconnecting the piping 53 with a standard T fitting that will both restore the water path and enable the unrestricted ultrasonic waves 57 and 58 to connect with the transducer in housing 55.

FIG. 6 provides some detail on the means for installing a replaceable Transducer/Launcher 52 under the bottom of a drain 16. Again, a conduit 53 is arranged to connect the transducer/launcher 52 with an appropriate cable or waveguide to the aboveground Transmitter/Receiver 22. This arrangement appears to be useful principally for new construction but, depending on circumstances could be adapted to retrofits as well.

FIG. 7A shows echo data at 2 frequencies for a Hayward Drain Cover which is typical of both new construction and retrofit situations. A larger and more defined echo was obtained at 660 kHz compared with 1 mHz, but both are quite acceptable.

FIG. 7B shows echo data at 1 mHz. In FIG. 7B-1 there is only a drain cover present.

The next FIG. 7B-2, contains the echo of a persons hand as well as the drain cover.

The last FIG. 7B-3 shows a 10× magnification of the horizontal time scale at the hand echo and we can see distinct groups of echo pulses. This my be due to more than one finger reflection or th hand orientation but it provides a charateristic “signature” which is useful for object classification purposes.

FIG. 7C shows the use of range gates to sort the hazard level based on distance from a drain. FIG. 7C-1 shows the drain cover echo within a range cell gate that would be the normal condition. FIG. 7C-2 again shows the drain cover echo and the Close Swimmer Range Cell. An echo in this cell would call for an immediate pump shutdown. This cell as shown, has an extent in range of about 15 inches beginning at the drain cover. FIG. 7C-3 shows a drain cover echo and a Far Swimmer Range Cell that begins at the end of the Close Swimmer Range Cell and extends for several feet. This cell is for monitoring swimmer activity and would not call for an immediate pump shutdown, but could be used to generate an warning/alarm signal when this cell is occupied.

FIG. 7C-4 is an example of a very high resolution test with a 3.5 mHz plastic film transducer. The middle echo is the water surface in a bucket filled with 6 inches of water showing the very fine resolution available for short range applications. The later right side echo is due to a second time around reflection and is exactly twice as far away in time as the water surface echo. It should be understood that more than one transducer can be employed in an installation and particularly for new construction can offer the best of both options with high resolution up close using high frequencies and longer range for distance coverage at low frequencies. This may be characterised as a dual mode configuration. (see also FIG. 9).

FIG. 8A shows in more detail echo data for the Drain Cover and a Hand about 5 inches from the cover and in a No-Go gate. We also can see in the lower panel of FIG. 8A the real time FFT display for the hand echo. This illustrates the signal to noise improvement that can be realized with the equivalent of a matched filter or correlation.

FIG. 8B shows the reduction in attenuation with a long sweep elbow compared with a conventional 90 degree Schedule 40 elbow.

FIG. 8C shows the improvement that can occur at some lower frequencies, in this case 200 kHz. All echoes are clearly identified for this U Tube test.

FIG. 9 is a simplified propagation model to show the general trends that relate frequency with relative attenuation and relative small target detectability. In general the higher the frequency the greater the attenuation, and the better the detectability providing that an adequate S/N ratio can be maintained. Likewise, lower frequencies suffer less attenuation but also do not detect small targets very well. In addition to this simplified model the literature shows many examples of what might be considered anomalous departures from the trend lines, but which are in reality cyclic variations in attenuation, perhaps due to specific propagation modes in a structure, that offer low loss windows. One must carefully choose the optimum frequencies for a system design. In this regard U.S. Pat. No. 5,289,436 Ultrasonic waveguide, J. H. Terhune, offers some interesting examples of low loss frequency windows in thin tubular structures.

While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, for use with a swimming pool and/or spa or whirlpool hydraulic system, wherein said hydraulic system includes at least one pool pump having inlet and outlet lines, a pool drain line, at least one pool main drain, and a pump control contactor and/or SVRS, said ASI comprising:

An active suction entrapment sensor (e.g. ultrasonic) that can assess the relative hazard based on swimmer proximity to the drain cover;

An Ultrasonic Transducer, one or more, to launch waves into the suction piping and/or drain system, and to receive echoes from the drain cover; swimmer limbs, hair or body; and the pool or water surface parallel to the drain cover; the mounting should be coaxial with the pipe to maintain axi-symmetry for the best ultrasonic wave performance;

A Transmitter/Pulser to electrically energize said ultrasonic transducer to launch waves into the suction piping and drain system;

A Receiver/Processor to detect the echoes electrical signals from the said ultrasonic transducer, and to receive echoes from objects of interest beyond the pool drain, including but not limited to, the drain cover, a swimmer's body or limb, or long hair in close proximity to the drain and/or cover, and the pool or water surface parallel to the drain cover;

A Logic and Control element to convert the detected signals into reliable information regarding a swimmer safety/hazard status;

An Output to provide a pump shutdown command if a close approach by a swimmer near a drain is measured;

A housing for the Transmitter and Receiver, Logic and Control that can be located in the pool equipment area;

A transducer mounting and cable adjacent to the pump inlet suction piping; and

Other suction side piping and fittings that optimize performance, such as sweep elbows, will be used instead of the standard Schedule 40, 90 degree elbows, for the waveguide mode.

Alarms, both local and remote, are important to alert operating personnel to a hazardous condition, visible and audible types are used;

Self calibration and self test are both available because the normal pool water level remains within a fairly narrow renge such that the surface echo range from the transducer, or drain cover, is accurately known, the presence of the water surface echo is important to assure the system normal operation;

Water velocity is available from doppler or time-of-flight measures for the waveguide installations; and

A pool alarm to respond to a person falling into the water is also inherent in the design because the transducers can act in a passive mode as well.

2. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, as claimed in claim 1, wherein the transducers for waveguide feed are replaceable, and can be housed in a manner to allow for normal immersion or dry operation by means of bonding behind a thin plastic window in contact with the suction waterflow.

3. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, as claimed in claim 1, wherein a means of venting air from the transducer housing is provided.

4. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, as claimed in claim 1, wherein Ultrasonic transducers may be piezoelectric, ferromagnetic, electromagnetic, plastic film, crystal, ceramic or others.

5. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, as claimed in claim 1, wherein CW, Spread Spectrum, FM, Tone Burst, Square Wave, Impulse and other forms of transducer excitation can be considered.

6. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the suction piping as a waveguide, as claimed in claim 1, wherein means for improving the S/N ratio and detectability can include passband filtering, matched filtering, correlation, integration, FFT, phase locking, and others; both analog and digital.

7. A machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains to house the sensor transducer, for use with a swimming pool and/or spa or whirlpool hydraulic system, wherein said hydraulic system includes at least one pool pump having inlet and outlet lines, a pool drain line, at least one pool main drain, and a pump control contactor and/or SVRS, said ASI comprising:

An active suction entrapment sensor (e.g. ultrasonic) that can assess the relative hazard based on swimmer proximity to the drain cover;

An Ultrasonic transducer, one or more, to launch waves into the drain, and to receive echoes from the drain cover, swimmer limbs, hair or body, and the pool or water surface parallel to the drain cover;

A Transmitter/Pulser to electrically energize said ultrasonic transducer to launch waves into the drain and cover;

A Receiver/Processor to detect the echoes electrical signals from the said ultrasonic transducer, and to receive echoes from objects of interest beyond the pool drain, including but not limited to, the drain cover, a swimmer's body or limb, or long hair in close proximity to the drain and/or cover, and the pool or water surface parallel to the drain cover;

A Logic and Control element to convert the detected signals into reliable information regarding a swimmer safety/hazard status;

An Output to provide a pump shutdown command if a close approach by a swimmer near a drain is measured;

A housing for the Transmitter and Receiver, Logic and Control that can be located in the pool equipment area;

A transducer mounting and cable, or in or under at least one main drain;

A main drain that has been modified with a removeable mounting provision for the transducer/cable assembly;

A conduit from the pool equipment pad to house and allow replacement of the transducer and cable assembly;

Alarms, both local and remote, are important to alert operating personnel to a hazardous condition, visible and audible types are used;

Self calibration and self test are both available because the normal pool water level remains within a fairly narrow renge such that the surface echo range from the transducer, or drain cover, is accurately known, the presence of the water surface echo is important to assure the system normal operation;

Water velocity is available from doppler or time-of-flight measures for the waveguide installations; and

A pool alarm to respond to a person falling into the water is also inherent in the design because the transducers can act in a passive mode as well.

8. A machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains to house the sensor transducer, as claimed in claim 7 the transducers are replaceable, and can be housed in a manner to allow for normal immersion or dry operation by means of bonding behind a thin plastic window in contact with the suction waterflow.

9. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains as claimed in claim 7, wherein a hydrophone can be integrated into the transducer housing for the purpose of improving swimmer detection, is provided.

10. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains, as claimed in claim 7 wherein Ultrasonic transducers may be piezoelectric, ferromagnetic, electromagnetic, plastic film, crystal, ceramic or others.

11. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains, as claimed in claim 7, wherein CW, Spread Spectrum, FM, Tone Burst, Square Wave, Impulse and other forms of transducer excitation can be considered.

12. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in new pool construction, using the drains, as claimed in claim 7, wherein means for improving the SIN ratio and detectability can include passband filtering, matched filtering, correlation, integration, FFT, phase locking, and others; both analog and digital.

13. A machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment, for retrofit pool installation using the suction piping as a waveguide, for use with a swimming pool and/or spa or whirlpool hydraulic system, wherein said hydraulic system includes at least one pool pump having inlet and outlet lines, a pool drain line, at least one pool main drain, and a pump control contactor and/or SVRS, said ASI comprising:

An active suction entrapment sensor (e.g. ultrasonic) that can assess the relative hazard based on swimmer proximity to the drain cover;

An Ultrasonic Transducer, one or more, to launch waves into the suction piping and/or drain system, and to receive echoes from the drain cover; swimmer limbs, hair or body; and the pool or water surface parallel to the drain cover; the mounting shold be coaxial with the pipe to maintain axi-symmetry for the best ultrasonic wave performance;

A Transmitter/Pulser to electrically energize said ultrasonic transducer to launch waves into the suction piping and drain system;

A Receiver/Processor to detect the echoes electrical signals from the said ultrasonic transducer, and to receive echoes from objects of interest beyond the pool drain, including but not limited to, the drain cover, a swimmer's body or limb, or long hair in close proximity to the drain and/or cover, and the pool or water surface parallel to the drain cover;

A Logic and Control element to convert the detected signals into reliable information regarding a swimmer safety/hazard status;

An Output to provide a pump shutdown command if a close approach by a swimmer near a drain is measured;

A housing for the Transmitter and Receiver, Logic and Control that can be located in the pool equipment area;

A transducer mounting and cable adjacent to the pump inlet suction piping;

Alarms, both local and remote, are important to alert operating personnel to a hazardous condition, visible and audible types are used;

Self calibration and self test are both available because the normal pool water level remains within a fairly narrow renge such that the surface echo range from the transducer, or drain cover, is accurately known, the presence of the water surface echo is important to assure the system normal operation;

Water velocity is available from doppler or time-of-flight measures for the waveguide installations; and

A pool alarm to respond to a person falling into the water is also inherent in the design because the transducers can act in a passive mode as well.

14. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in retrofit installations, using the suction piping as a waveguide, as claimed in claim 13, wherein the transducers for waveguide feed are replaceable, and can be housed in a manner to allow for normal immersion or dry operation by means of bonding behind a thin plastic window in contact with the suction waterflow.

15. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in retrofit installations, using the suction piping as a waveguide, as claimed in claim 13, wherein a means of venting air from the transducer housing is provided.

16. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in retrofit installations, using the suction piping as a waveguide, as claimed in claim 13 wherein Ultrasonic transducers may be piezoelectric, ferromagnetic, electromagnetic, plastic film, crystal, ceramic or others.

17. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in retrofit installations, using the suction piping as a waveguide, as claimed in claim 13, wherein CW, Spread Spectrum, FM, Tone Burst, Square Wave, Impulse and other forms of transducer excitation can be considered.

18. The machine for Anticipatory Sensing and Intervention (ASI) to avoid swimmer entrapment in retrofit installations using the suction piping as a waveguide, as claimed in claim 13, wherein means for improving the SIN ratio and detectability can include passband filtering, matched filtering, correlation, integration, FFT, phase locking, and others; both analog and digital.