Abstract:
A water flow detector has a spring driven mechanical timer responsive to the movement of a lever. The lever is connected to a paddle. The paddle is responsive to the flow of water in a pipe. The detector via the spring driven timer responds to the flow of water in the pipe after a predetermined delay.

Description:
FIELD 
       [0001]    The application pertains to a water flow detector which incorporates a spring driven escapement which provides a delay function. An adjustable timing gap is established between an end of a rack for the escapement and a linearly movable stop to set overall timing delay. 
       BACKGROUND 
       [0002]    Water flow detectors having a timer responsive to movement of a lever connected to a paddle are known. A known water flow detector uses an air bleed timer. U.S. Pat. No. 6,331,820, entitled Explosion Proof Water Flow Detector, issued Dec. 18, 2001, discloses a paddle type flow detector which relies on an air bleed timer. U.S. Pat. No. 4,782,333, entitled Water-flow Detector With Rapid Switching, issued Nov. 1, 1988, discloses an air bleed timer. Both of these patents are assigned to the assignee hereof and incorporated herein by reference. 
         [0003]    In general a water flow detector using an air bleed timer has a cam. The cam, when in a first position, maintains a switch assembly in a first state. The cam when in a second position enables the switch assembly to move to a second state. The lever when moved to a second position enables the cam to move from the first position to the second position. 
         [0004]    The time it takes the cam to move depends upon the rate at which air is set to bleed out of an air chamber formed by a diaphragm. If the air is set to bleed out quickly, the cam will move quickly from the first to the second position. If the air is set to bleed out slowly, the cam will move slowly from the first to the second position and it will take longer for the switch to move from the first to the second state. 
         [0005]    The lever is moved from the first position to the second position by the flow of water in a riser pipe of a fire sprinkler assembly. The water causes the paddle to move from a first to a second position. If the lever is not in the second position, the cam cannot move from the first to the second position. Accordingly the switch can not move from the first state to the second state. Whether the cam moves from the first to the second position depends on the rate of air bleed and the duration of suitable water flow. 
         [0006]    If the water flow stops before the air bleed is complete, the cam will be moved back to the first position by the lever prior to the cam moving to the second position. The switch will not move to the second state. For instance, if the bleed duration is 50 seconds then the cam will move from the first to the second position in 50 seconds so long as the lever is maintained in the 2 nd  position by the water flow. 
         [0007]    If the lever is not maintained in a second position by the water flow for 50 seconds then the cam will not be able to move to the second position. The switch will not move to the second state. Accordingly the longer the bleed time, the longer the water flow most continue for the switch to move from the first to the second state. The shorter the bleed time the shorter amount of time the water flow most continue for the switch to orient from the first state to the second state. 
         [0008]    Another embodiment is disclosed in pending U. S. application Ser. No. 12/974,637 filed Dec. 21, 2010 and entitled, Water Flow Detector. The &#39;637 application is assigned to the assignee hereof and incorporated by reference. 
         [0009]    While timers of the type described above have been found to be useful in providing needed delays, it would be desirable to be able to reduce their complexity and cost while still providing an adjustable time delay. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an overall diagram of an embodiment hereof; 
           [0011]      FIG. 2  illustrates a timer/brake installed on an embodiment as in  FIG. 1 ; 
           [0012]      FIG. 3  illustrates the embodiment of  FIG. 2  with the timer/brake removed exposing the associated rack; 
           [0013]      FIG. 4  illustrates the embodiment of  FIG. 3  with a gap between the rack and the slide nut; and 
           [0014]      FIG. 5  illustrates the embodiment of  FIG. 3  with a delay adjusting knob installed. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    While disclosed embodiments can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles thereof as well as the best mode of practicing same, and is not intended to limit the application or claims to the specific embodiment illustrated. 
         [0016]    In one aspect, a delay mechanism usable in a flow detector includes first and second mechanical elements. The first element includes an axially movable shaft which carries a switch activating cam. The initial position of the shaft is linearly adjustable to establish a free fall timing gap. 
         [0017]    A second element comprises a spring driven escapement, a fixed timer, which limits the rate at which the shaft can move axially in response to the spring force. By adjusting the length of the free fall timing gap, the time duration that the second element operates before the cam changes position of the switch can be varied. 
         [0018]    Embodiments hereof incorporate an adjustable nut, barrel gear and dial/knob with meshing gear teeth which can index the nut along the shaft via a thread on the shaft. The nut then forms a stop against a fixed time delay, the second element, which includes a gear rack of a verge and foliot-type escapement which provides the time delay function. Changing the length of the free fall timing gap (distance between the nut and gear rack in rest position) changes the length of time that the timer is working, prior to a switch change, and hence the time delay. 
         [0019]    In accordance herewith, the time delay is altered by adjusting a manually rotatable dial. Rotating the dial then changes the timing gap. 
         [0020]    Advantageously, such embodiments do not require electrical energy for the timer mechanism. All required energy is supplied by an incorporated spring. 
         [0021]    In yet another aspect hereof, the time delay mechanism is activated by movement of a spring biased water flow sensing paddle from a no flow to a flow position. As those of skill will understand, the paddle is installed in a water supply pipe which is part of a fire suppression sprinkling system. 
         [0022]    When the paddle moves to the flow indicating position, a second spring, part of the delay mechanism, pulls the shaft and nut, axially until the nut engages an adjacent end of the rack. This in turn causes the timer to operate for a period of time determined by the initial length of the gap, which alters the axial starting position of the rack and the delay provided thereby. 
         [0023]    When the cam has moved a required distance, in response to the driving force of the detector&#39;s second spring, a switch closing/opening can be produced indicative of sensed flow. The resulting electrical signal can in turn be detected at a monitoring, or fire detecting station, or, system. When flow ceases, the detector can automatically reset itself. 
         [0024]      FIG. 1  illustrates an embodiment of a water flow detector  10  in accordance herewith. The detector  10  can be carried on a mounting plate  12 . 
         [0025]    A flow indicating lever  14  can be rotatably carried by the plate  12 , biased to a no-flow state by a spring  18   a.  Lever  14  can move from the indicated no flow position to the flow indicating position, indicted in phantom, in response to water flow F in an adjacent pipe P. 
         [0026]    Detector  10  carries first and second mechanical structures,  20 ,  22  which provide a delay in responding to the movement of the lever  14 . Structure  20  includes an axially movable shaft  26  with a threaded end  26   a.  The end  26   a  carries a nut  26   b  threaded onto the portion  26   a  and rotatable therealong. 
         [0027]    The nut  26   b  also carries an interior set of threads  26   c  which can be used to rotate the nut  26   b  along the shaft  26   a,  discussed subsequently. 
         [0028]    The second structure, a timer/brake assembly,  22  includes a rack  22   a , with teeth  22   a - 1 , and associated escapement mechanism  22   b.  The mechanism  22   b  permits the rack to move freely in a slip direction  22 - 1 . Movement opposite the direction  22 - 1 , a timed direction, is regulated by operation of the escapement and rack combination which implements the timer/brake  22 . 
         [0029]    Those of skill will appreciate that one implementation of the timer/brake  22  could be a verge and foliot-type escapement mechanism. Other types of mechanisms could be used, without limitation, without departing from the spirit and scope hereof. 
         [0030]    The detector  10  also includes a switch and cam mechanism  30  which can produce a contact opening or closure in response to lever  14  moving to the flow position, and subsequent to a delay provided by the mechanism  20 ,  22 . Cam  32  is carried on shaft  26 . The switches  34   a, b  open or close in response to movement of cam  32 . 
         [0031]    A spring  18   b  which is extended when the lever  14  is biased to the no flow condition, provides a force to draw the cam  32  axially toward the switches  34   a, b  once the lever  14  moves into the flow indicating position. The shaft  26 , also drawn by the spring  18   b  closes a gap  10 - 1  between the nut  26   b  and the rack  22   a.    
         [0032]    When surface  26   d,  see  FIG. 1 , of the nut  26   b  contacts the end surface  22   c  of the rack  22   a,  the timer mechanism  22  starts to function. This brakes motion of shaft  26  thereby delaying the time when cam  32  can trip the switches  34   a, b.    
         [0033]    Once the switches  34   a, b  are tripped by the cam  32 , and water flow ceases, the lever  14  will return to the no flow position. In this condition surface  26   e  of the shaft  26  forces the rack  22   a  to a no flow state by moving it in the slip direction  22 - 1 . This represents a common initial state of the apparatus prior to the lever  14  moving toward a flow indicating state. 
         [0034]    In summary, when the gap  10 - 1  is increased, the timer/brake  22  is engaged later and there is less of a delay. When the gap  10 - 1  is decreased, the timer/brake  22  is engaged sooner and a longer delay results. 
         [0035]      FIGS. 2-5  illustrate aspects of another embodiment hereof. Elements previously discussed have been assigned the same identification numerals and need not be discussed further. 
         [0036]      FIG. 2  illustrates the timer  22  installed in place on an apparatus comparable to the apparatus  10  of  FIG. 1 . The timer  22  is in a fixed position on the assembly.  FIG. 2  illustrates the location of the spring  18   b  and the direction that the spring  18   b  pulls on the main shaft  26  and cam assembly  32 . 
         [0037]    The switches  34   a, b  are illustrated in a standby position. The main flow sensing pivot shaft  14  is in a no flow state, holding the shaft/cam assembly  26 / 32  to the right 
         [0038]    In  FIG. 3 , timer  22  has been removed to expose rack  22   a  and related components in an initial no flow state. The gap  10 - 1  has been reduced substantially to zero in  FIG. 3 . In this configuration, the timer/brake  22  will produce a maximum delay. 
         [0039]      FIG. 4  illustrates the gap  10 - 1  produced by rotating the gear  26   c  to move the nut  26   b  away from the rack  22 . To produce a reduced delay. Once the surface  26   d - 1  contacts end  22   c  of the rack  22 , the timer/brake  22  will start to function to provide a delay. 
         [0040]      FIG. 5  illustrates a knob or dial  40  with teeth  42  that mesh with the teeth  27   b  of pinion gear  27   a.  Pinion  27   a  is slidably locked to the nut  26   b  by grooves  26   b - 1  in nut  26   b.  The grooves  26   b - 1  slidably engage radial members  27   c  of the pinion  27   a.  Turning the dial  40  rotates the nut  26   b  thereby sliding it along the threaded portion  26   a  of timer shaft  26 . As a result the delay can be increased or decreased. In accordance with the above, the pinion gear  27   a  rotates in response to movement of the knob  40  which in turn causes the nut  26   b  to both rotate (due to the grooves  26   b - 1  and extending radial members  27   c ) and move axially relative to the shaft  25  as it rotates on threads  26   a.    
         [0041]    With respect to  FIG. 5 , in summary, the pinion gear  27   a  rotates the nut  26   b  as the knob  40  is being turned. Gear  27   a  has teeth  27   b  that interface with the teeth  42  on the knob  40  and also has interlock groves  27   c  along which the nut  26   b  slides. The pinion  27   a  is stationary except for rotation when the knob  40  spins it. 
         [0042]    In response to rotating the knob  40 , the threaded nut  26   b  slides on the shaft  26   a  as shown. This sliding in turn adjusts the length of the gap  10 - 1  as described above. The timer shaft  26   a,  during timing stroke, is locked to the nut  26   b  and pulls the nut  26   b  along. As a result, nut  26   b  glides axially through the pinion gear  27   a.    
         [0043]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims. Further, logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be add to, or removed from the described embodiments.