Patent ID: 12208290

DETAILED DESCRIPTION OF EMBODIMENTS

Several terms relating to the present invention will be defined prior to describing the invention in detail. It should be noted that the following definitions are used throughout this application.

For the purpose of the present invention, directional terms such as “top”, “bottom”, “below”, “above”, “left”, “right”, “horizontal”, “vertical”, “upper”, “lower”, “up”, “down”, etc. are merely used for convenience in describing the various implementations of the present invention. The assemblies demonstrating the present invention may be oriented in various ways.

For the purpose of the present invention, the term “plurality” refers to two or more than two.

For the purpose of the present invention, the term “hinged element” refers to an element provided with at least one hinge or having at least one hinge point enabling swivel of the element about the hinge point.

For the purpose of the present invention, the term “segment” refers to one of the parts into which an assembly is separates or is divided.

For the purpose of the present invention, the term “air exchange backup unit” refers to a device, energized by human power, configured for introducing fresh air into a protection shelter during an event of electric power failure.

For the purpose of the present invention, the term “foldable” refers to a structure that can be folded down into a small space when it is not being used.

For the purpose of the present invention, the term “inverted tooth chain” or “silent chain” refers to a type of drive chain with teeth formed on its links to engage with standard or modified gear wheels.

For the purpose of the present invention, the term “pitch” refers to the distance between successive corresponding physical occurrences, such as rollers in a roller chain.

The term “NBC” is used throughout this text as a general abbreviate for all kinds of hazardous agents including any one of Nuclear, Biological, Chemical and Radiological threats or any combination thereof. Such combinations may include for instance: NBC, CBRN, CBR, BC, B and C.

With reference to the figures, according to one embodiment of the invention, there is shown inFIG.1a front view of an NBC filtration system for collective protection shelters generally referenced10.FIG.2depicts a perspective view of a similar NBC filtration system with dashed lines representing nearby internal boundary of the protection shelter. Visible inFIGS.1and2, are a prefilter14, a filter unit30and an air exchange backup unit generally referenced20. The prefilter14, intended to hold coarse particles, is fitted to an air intake embedded in the concrete wall of the building during construction. The air intake may further include a blast valve as known in the art. The filter unit30typically includes a particulate filter and a gas adsorption filter. The filter unit30may further include an internal bypass and a change-over valve (not shown) which are out of the scope of the present invention. Further shown inFIG.4is a blower40airflow coupled to the filter unit30. The blower40is typically covered by a cover32serving also as a mounting bracket fixing the blower40to the wall of the protection shelter. The air exchange backup unit20is mechanically coupled to the blower40and manually operated in an event of power failure to power the blower40by transmission of rotational motion which rotates an impeller76(FIG.9) of the blower40.

According to an embodiment, the blower40is normally driven by an electric motor42as long as electric power is available. The air exchange backup unit20may be mechanically coupled to the blower40directly, or through the electric motor42as will be explained herein below. The air exchange backup unit comprises a plurality of hinged segments, here shown by a way of example with three segments22(a, bandc) serially linked to each other. The linked hinged segments forming a foldable arm, shown partially folded inFIGS.3and4.

With reference toFIG.5, a first end24of the air exchange backup unit20is swiveably attached to the electric motor42driving the blower40. During operation of the air exchange backup unit, in an event of power failure, rotational motion is transmitted from the hand crank28through the hinged segments22(a, bandc) as will be hereinafter explained, typically through an unidirectional freewheel, to a shaft44(FIG.8) of the electric motor42.

A second end26of the air exchange backup unit20carries a detachable hand crank28. Rotation of the hand crank28at normal manual operation of about 40 rpm, rotates the shaft44of the electric motor42at substantially a rated speed of the electric motor. The second end26of the air exchange backup unit20is firmly attachable for instance by a dedicated fixed bracket60to a wall of the protection shelter at a convenient position for manual cranking of the hand crank. The air exchange backup unit20may selectively be folded up at normal times as shown inFIGS.3and4.

With reference toFIGS.3and4, the air exchange backup unit20is shown in a partially folded state, in which the hinged segments22are folded about the hinges to form a Z letter shape. It will be understood that the segments may be further folded up to a point where the lower segment22ais in contact with the upper segment22csuch that the air exchange backup unit20is hidden behind the cover32serving also as a mounting bracket of the blower40. As a result, the air exchange backup unit20practically turns invisible to the occupants of the protection shelter. As shown inFIG.2the NBC filtration system10as a whole is fitted to a wall of the protection shelter near the ceiling. Accordingly, during normal times, when the air exchange backup unit20is folded up, the NBC filtration system10does not interfere with regular activity taking place in the protection shelter.

As mentioned in the background, in real installations the NBC filtration system is fitted at different locations and different heights. The different locations are enforced by variations in position of the intake pipe between building constructions. The embodiments of the present invention solves this difficulty by simple adaptation of the air exchange backup unit20folding arm construction to any installation position. It should be noted that although shown vertically oriented inFIGS.1and2, the air exchange backup unit20may compensate for different mounting positions by being partially folded or diagonally fixed to the wall of the protection shelter even during operation at power failure. The above described rotational motion is transmitted from the hand crank28through the hinged segments22(a, bandc) with the same efficiency in any angular settlement of the hinged segments.

As mentioned above, during operation of the air exchange backup unit20, in an event of power failure, rotational motion is transmitted from the hand crank28through the hinged segments22to the electric motor42. The way of transmittal of the rotational motion will be explained with reference toFIGS.6and7. According to an embodiment there are shown inFIG.6three hinged segments22linked to each other. The hinged segments use a simple open construction exposing the drive system. Each of the hinged segments22is provided with a mechanical drive52transmitting rotational motion from one end of the segment to the other end. For example by a pair of sheaves, pulleys or sprockets, each fitted at one end of the segment, rotatively connected by a belt or chain drive. Alternately a pair or plurality of mating gears may be used. Optionally one or all of the mechanical drives52may define a transmission ratio or a transmission stage. According to an optional embodiment, at least one of the hinged segments22comprises at least one stage of a first speed increasing transmission. Alternately the first speed increasing transmission may be located separately at one end of the air exchange backup unit20, as will be hereinafter demonstrated.

In addition to the above mechanical drive, transmitting rotational motion from one end of the segment to the other end, the hinged segments22are configured for transmission of rotational motion between each other. This is shown with more clarity inFIG.6, where two segments22ofFIG.5are shown exploded. The structural elements53are made as a flat elongated body provided with openings54at both ends. An integral shaft bearing55(also known as water pump bearing), or a dedicated bearing assembly having a shaft56passing through and extending at both sides, is provided to each of the openings54. The outer diameter of the bearing55or the housing of the bearing55serves as a hinge linking the structural elements53. The structural elements53are swiveable about the bearing55, by the bearings55having a free fit in the openings54. A retaining clip may be further provided to hold the bearing55in position. Sprockets57,58are fitted to both ends of the shaft56of bearing55. The sprockets57,58may be fixedly fitted to the shaft56by a press fit, a key, a flat face, a locking screw or any other locking element that prevents free rotation of the sprockets57,58about the shaft56. As a result, the shaft56is transmitting rotational motion between sprocket58fitted to one end of the shaft56and sprocket57fitted to the other end of the shaft56. Sprocket58is driven by mechanical drive52aof segment22aas described above. And Sprocket57is driving the mechanical drive52bof segment22b. It will be noted that the shaft56shares the same axis as the hinge between the segments22a,22bdefined by bearing55. Accordingly, each of the hinges pairing the hinged segments22(a, bandc) (FIG.6), is provided with a rotatable shaft56transmitting rotational motion from one segment to the other and sharing the same axis as the hinge axis. The shaft56transmitting rotational motion between the segments22(a, bandc). The ratio between diameter or teeth number of sprockets57and58indicates the speed increasing amount of each stage or mechanical drive of each segment.

FIG.5, depicts a perspective rear view of the air exchange backup unit20and blower40taken out of the NBC filtration system. The air exchange backup unit generally referenced20is shown halfway folded. The second end26of the air exchange backup unit20is provided with a circumferential protrusion36and a locking pin34. The second end26may be firmly attached to the dedicated fixed bracket60(FIG.4), by engagement of the circumferential protrusion36into a compatible pocket62provided with circumferential recess64of the dedicated fixed bracket60. The locking pin34may be engaged into a locking hole66of the bracket60to prevent movement of the second end26of the air exchange backup unit20, during operation of the hand crank28. The route of directing the second end26of the air exchange backup unit20into the fixed bracket60is demonstrated by an arrow marked68(FIG.4). It will be understood that other means for firmly attaching the second end26of the air exchange backup unit20to a wall of the protection shelter may be provided. Such other means may include a mortise and tenon, hand operated fasteners, lever latching fasteners, cone couplers and other known means.

With reference toFIGS.4and5, a suction port46of the blower40is airflow coupled to the filter unit30through a flexible duct70. The blowout port48of blower40, is open to the space of the protection shelter such that filtered air is spread into the space without restriction. The blower40is driven by the electric motor42either directly or through a second speed increasing transmission74as shown inFIG.4. For economic and long term reliability reasons a standard 4-pole induction motor42may be preferable.

With reference toFIG.8, the blower40and motor42are moved from position in relation to the air exchange backup unit20. Covers38aand38cof segments22aand22crespectively are also moved from position to expose transmission stages72aand72cof the first speed increasing transmission of air exchange backup unit generally referenced20. It will be noted that according to the embodiment the structural elements are made with a cavity23and provided with a cover38protecting the user from contact with moving drive elements. According to the embodiment, each of the hinged segments22is provided with a mechanical drive72(a, bandc) transmitting rotational motion from one end of the segment to the other end. According to the shown embodiment, each of the hinged segments22(a, bandc) includes one stage of the first speed increasing transmission of the air exchange backup unit20.

With reference toFIG.9, an air exchange backup unit is shown with the structural elements removed, exposing the transmission elements. According to an embodiment, the first speed increasing transmission is configured as a roller chain drive including 3 stages72(a,bandc). Each of the links pairing the hinged segment22(a, bandc) is provided with a rotatable shaft88,98sharing the same axis as the hinge axis. Obviously any other number of hinged segments and transmission stages may be used, however for reason of efficiency, the optimal number is the minimum number that delivers the desired speed increasing ratio. The pitch size of the roller chain drive is selected between 6 mm and 10 mm. It will be understood that the different stages of the first speed increasing transmission may accept different pitch size due to the different moment and rotational speed related to each of the stages.

In more detail, yet with reference toFIG.9, during manual operation of the hand crank28in an event of power failure, a first sprocket82is directly rotated by the hand crank28through an input shaft81. The first sprocket82rotates a second sprocket84preferably smaller than the first sprocket82, via a first drive chain86. The first sprocket82, first drive chain86and second sprocket84are forming together the first stage72aof the first speed increasing transmission of air exchange backup unit20. As shown inFIG.9, the second sprocket84is mounted on one end of a first intermediate shaft88defining also a hinge axis between the first segment22aand the second segment22bof the foldable arm constituting the air exchange backup unit20. A third sprocket92is mounted on the other end of the first intermediate shaft88, thus accepting the same rotational speed as the second sprocket84.

The third sprocket92rotates a forth sprocket94preferably smaller than the third sprocket92, via a second drive chain96. The third sprocket92, second drive chain96and fourth sprocket94are forming together the second stage72bof the first speed increasing transmission of air exchange backup unit20. The fourth sprocket94is mounted on one end of a second intermediate shaft98defining also a hinge axis between the second segment22band the third segment22cof the foldable arm constituting the air exchange backup unit20. A fifth sprocket102is mounted on the other end of the second intermediate shaft98, thus accepting the same rotational speed as the fourth sprocket94.

The fifth sprocket102rotates a last sprocket104preferably smaller than the fifth sprocket102, via a third drive chain106. The fifth sprocket102, third drive chain106and last sprocket104are forming together the third stage72cof the first speed increasing transmission of air exchange backup unit20.

The last sprocket104is fitted to a first end107of the motor shaft44through an unidirectional freewheel also known as freewheel clutch or freewheel bearing. The unidirectional freewheel permits rotation of the motor shaft44by the air exchange backup unit20, but prevents rotation of the first speed increasing transmission elements by freewheeling when the motor is electrically energized. It will be understood that different types of unidirectional or clutch mechanisms can be used alternately, for instance a ratchet mechanism or a wound spring mechanism as known in the art.

Yet with reference toFIG.9, The second speed increasing transmission74, if applicable, comprises a first sprocket110fixed to a second end108of the motor shaft44, a drive chain112, and a second sprocket114, smaller than the first sprocket110. The second sprocket114of the second speed increasing transmission74is fitted to a first end of a blower shaft116. The second end of the blower shaft116carries an impeller76of the blower40.

The second speed increasing transmission74driving the blower40is capable of driving the impeller76of the blower at a rotational speed of above 3000 rpm using a motor42of the known 4-pole induction type. To minimize transmission losses, the second speed increasing transmission74may be a low friction, efficient drive system selected between some options including: a multi-groove V belt drive, toothed belt drive, a roller chain drive or an inverted tooth chain drive also known as silent chain. Due to the high speed and low torque of this second speed increasing transmission, if a roller chain drive or a silent chain drive is utilized, than the pitch size is selected between 3 mm and 6 mm. It will be understood that other transmission types can be used such as direct gear drive, single or multiple V belt drive, flat belt drive and ladder chain drive.

With reference toFIG.10there is shown a different embodiment where four segments22(a, b, candd) are used. Each of the segments is provided with one stage52(a, b, candd) of the first speed increasing transmission. Due to a possible higher overall transmission ratio than that of the three segment construction, there is no need for a second speed increasing transmission and a motor42of rated speed preferably higher than 3000 rpm is directly driving the blower40. The air exchange backup unit20is driving the other end of the shaft of motor44, in an event of power failure and manual operation of the hand crank28.

With reference toFIG.11there is shown an additional embodiment where only two segments22aand22bare used. As shown in the embodiment ofFIG.11, the sprockets59at both ends of each segment22aand22bare of the same size. Accordingly there is no speed increasing in the air exchange backup unit20. For the speed increasing task there is provided a dedicated speed increasing transmission39which is fitted between the air exchange backup unit20and the motor42. It will be understood however that any combination of speed increasing transmission stages may be used. The air exchange backup unit20may be provided with certain first speed increasing ratio while the dedicated speed increasing transmission39provides an additional second speed increasing ratio calculated to provide the overall required speed increasing ratio.

The present invention seeks protection regarding the device as described above, as well as the method steps taken to accomplish the desired result of introducing fresh air into the protection shelter during an event of a power failure, using a near ceiling mounted NBC filtration system and an air exchange backup unit of a foldable arm structure.

Accordingly and with reference toFIG.12, a method is provided comprising one or more of the steps below:

a. Providing a near ceiling mounted NBC filtration system comprising: a filter unit; a blower driven by an electric motor; an air exchange backup unit having a first end swiveably attached to the electric motor; and a detachable hand crank selectively fitted to a second end of the air exchange backup unit. The air exchange backup unit comprising a plurality of hinged segments serially linked to each other to form a foldable arm. The hinged segments are configured for transmission of rotational motion between each other.
b. Expanding the air exchange backup unit in an event of a power failure. Indicated as activities120and122of the flowchart ofFIG.12.
c. Attaching the second end of the air exchange backup unit to a wall of a protection shelter at a convenient position for manual cranking of the hand crank. Indicated as activity124of the flowchart.
d. Attaching the detachable hand crank to the second end of the air exchange backup unit. Indicated as activity126of the flowchart.
e. Cranking the hand crank while said power failure continues. Indicated as activity128and decision130of the flowchart.
The method may further include the steps of:
f. Stopping the cranking operation when electric power is revived. Indicated as activity132of the flowchart.
g. Detaching the detachable hand crank from the second end of the air exchange backup unit. Indicated as activity134of the flowchart.
h. Detaching the second end of the air exchange backup unit from the wall of the protection shelter. Indicated as activity136of the flowchart.
i. Folding up the air exchange backup unit. Indicated as activity138of the flowchart.

It will be understood that while activities120to128of the flowchart are required to start manual operation of the air exchange backup unit, the following activities132to138are optional or may be carried out at a later time or by a dedicated maintenance person that may further check the system before bringing it back to the folded state.

It will be appreciated that the specific embodiments of the present invention described above and illustrated in the accompanying drawings are set forth merely for purposes of example. Other variations, modifications, and applications of the present invention will readily occur to those skilled in the art. It is therefore clarified that all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.