Abstract:
An anti-dry start device is provided for preventing the operation of a powered pressure washer in the absence of sufficient inlet fluid pressure, the device comprising a pressure switch removably mounted into a fitting installed in the inlet line to the pressure washer, the device further comprising an electrical interconnection between the pressure switch and an ignition system of the pressure washer, whereby the pressure switch is adapted to disrupt power to the pressure washer ignition switch when the inlet pressure is below a preset threshold.

Description:
RELATED INVENTION 
       [0001]    This application is related to and claims priority from U.S. Provisional Application No. 60/755,967, filed Jan. 3, 2006, entitled “Anti-Dry Start Device”, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to powered pressure washers and more particularly to a device for preventing powered pressure washers from being started in a dry condition. 
       BACKGROUND OF THE INVENTION 
       [0003]    Powered pressure washers are connectable to a water supply (e.g., a residential water line or other standard water supply via a hose or hose connection) and include a pump unit for discharging a jet of water at an increased pressure. Powered pressure washers are used for a variety of purposes including cleaning of decks, driveways and other surfaces, preparation of walls for painting and for removal of graffiti, etc. Known powered pressure washers include gasoline-powered pressure washers and electrically powered pressure washers. 
         [0004]    Starting a powered pressure washer without water being delivered to the washer is known as dry starting. Dry starting of a powered pressure washer can result in damage to the pump unit of the powered pressure washer. Operation of a powered pressure washer with a reduced flow of water delivered to the powered pressure washer (e.g., a low pressure condition) can also lead to damage of the pump unit. Such a condition might result for example if a hose supplying water to the pressure washer becomes constricted or kinked. The cost of repairing or replacing a damaged pump unit can be very expensive, sometimes representing as much as two-thirds of the replacement cost for the entire powered pressure washer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a side elevation view of an anti-dry start device according to an exemplary embodiment of the invention. 
           [0006]      FIG. 2  is a side elevation view of an anti-dry start device according to an alternate embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0007]    Referring to the drawing, there is shown in  FIG. 1  an anti-dry start device  10  for a powered pressure washer. As described below in greater detail, the anti-dry start device  10  is adapted to prevent a powered pressure washer connected to the device  10  from being started unless water is being delivered to the device  10  (e.g., from a hose connected to a residential water line). The powered pressure washer most preferably includes a gas-powered engine. The present invention, however is not so limited and has potential application to other types of powered pressure washers (e.g., electrical, hydraulic, etc.). 
         [0008]    The anti-dry start device  10  includes a central body  12  defining an open interior having opposite ends  14 ,  16  from which water will respectively be received from a source of water (e.g., a hose) and delivered to a powered pressure washer. Adjacent end  14  of central body  12 , the device  10  includes a first fitting  18  adapted for attachment to the water source. The depicted device  10  is adapted for attachment to a hose and, therefore, the first fitting  18  preferably includes female hose threads not shown but contained within a female connector  23  located at a first end of the device  10 . The threads are preferably sized to connect with a standard garden hose connection or spigot (e.g., ¾ inch hose threads). The device  10  includes a second fitting  22  coupled to end  16  of central body  12 . The depicted device  10  is adapted for use with powered pressure washers connectable to a hose for receiving water (e.g., from a residential water line). The second fitting  22 , therefore, includes male hose threads  20  adjacent an end of the second fitting to provide for attachment of the device  10  to the powered pressure washer. The threaded fittings are conventional and, therefore, no further discussion is necessary. 
         [0009]    The anti-dry start device  10  includes a pressure switch  24  coupled to the central body  12 . As shown, the pressure switch  24  is located such that an end  26  of switch  24  is in fluid communication with the interior of central body  12  to respond (e.g., switch) in the presence of water delivered at a sufficient pressure into the central body  12  from a water source. Pressure switches are, per se known, and no further description is necessary. 
         [0010]    In the depicted device  10 , the central body  12  is embodied as a tee having ¾ inch internal threads (not shown) at opposite ends and an intermediate tap  28  having ¼ inch internal threads. As shown, the ¼ inch internal threads of tap  28  provide for threaded attachment of an externally threaded portion of the pressure switch  24  to the central body  12 . In the illustrated embodiment, the first and second fittings  18 ,  22  are attached to the central body  12 , such as with threads. Specifically, the first fitting  18  includes ¾ inch N.P.T. male threads  30  opposite the female connector  23  for threaded attachment of the first fitting  18  to end  14  of central body  12 . As shown, the second fitting  22  includes ¾ inch N.P.T. male threads that mate with internal threads formed in the end  16  of central body  12  to couple the second fitting  22  to the central body  12 . Preferably, a non-toxic thread sealer is used for the threaded connections. For example a rubber gasket seal may be included in the female connector  23 . While the center body  12  in above discussion is described as separate from the first and second fittings, it should be readily apparent that the fittings and the body can be formed as an integral component. Also, while threads are illustrated and discussed, it should be readily apparent that any connection mechanism can be used, such as a bayonet-connection. 
         [0011]    The anti-dry start device  10  includes a tee tap connector  36  adapted to provide electrical connection between the pressure switch  24  and the ignition system of a powered pressure washer. Preferably, the device  10  is adapted for connection to a 12 volt DC ignition system, or similar ignition system typically included on gas-powered pressure washers. The tee tap connector  36  includes an insulated female terminal  38  adapted for connection to the ignition system of the powered pressure washer (e.g., by a self-piercing wire connector). The tee tap connector  36  also includes an insulated male terminal  40  adapted for mating connection to the female terminal  38  of the tee tap connector  36 . An elongated wire lead  42  provides electrical connection between the tee tap connector  36  and the pressure switch  24 . More particularly, the wire lead  42  is coupled at one end to the male terminal  40  of the tee tap connector  36 . The opposite end of the wire lead  42  is coupled to an insulated female spade terminal  44 , such as by crimping. The spade terminal  44  is, in turn, coupled to the pressure switch  24 , such as by clipping the female connector onto a button head or a contact terminal. Preferably the connection is removable for replacement purposes. The depicted wire lead  42  is illustrated with a break to indicate that any suitable length for wire lead  42  could be chosen. However, for most applications a length of 24 inches should be sufficient to extend between the pressure switch  24  and the female terminal  38  of the tee tap connector  36  when the device  10  is connected to a powered pressure washer. 
         [0012]    Installation of the anti-dry start device  10  is as follows. The second fitting  22  of device  10  is connected to the powered pressure washer by threadedly engaging the threads  20  of the second fitting  22  with mating threads on the powered pressure washer. The device  10  is also connected to a water supply, for example by threadedly engaging a water hose to the female hose threads of the first fitting  18 . Connected in this manner, water that is supplied to the device  10  by the water supply will be delivered to the powered pressure washer via the interior of the central body  12 . Electrical connection between the pressure switch  24  of device  10  and the ignition system of the powered pressure washer is then made by engaging the male terminal  40  of the tee tap connector  36  to the female terminal  38  of the tee tap connector  36 . As discussed above, the female terminal  38  of the tee tap connector  36  is electrically coupled to the ignition system of the powered pressure washer in a well known manner. The depicted device  10  is adapted for relatively simple installation estimated to take approximately 3 to 5 minutes. As should be apparent from the above description, the pressure switch  24  is connected into the ignition wiring system, preventing ignition unless the pressure switch is activated. 
         [0013]    The operation of the anti-dry start device  10  is as follows. The electrical connection between the pressure switch  24  and the pressure washer functions to disable the ignition system of the pressure washer in the absence of pressure applied to the pressure switch  24  by water in the interior of the central body  12 . As a result, the powered pressure washer can not be started when water is not being supplied to the pressure washer. The device  10 , therefore, desirably serves to protect the pump unit of pressure washer from damage otherwise caused by starting the pressure washer in a dry condition. This serves to prolong pump life and avoid costly pump repairs, which may represent as much as two-thirds the cost of replacing the entire pressure washer. 
         [0014]    In some cases, the pressure washer uses a plastic or non-metallic nut that is designed to attach to threads  20  of device  10 . Such a configuration could compromise the path to ground, which is used to disable the 12 volt ignition system of the pressure washer unit in the absence of water pressure. Referring to  FIG. 1 , an optional grounding system is shown. More specifically, the device  10  includes a brass or metallic nut  50 , such as a ¼ inch,  18  thread brass hex nut. A ring terminal  52  is located about the threaded end  26  of the switch  24 . The ring terminal  52  is preferably a ⅝ inch diameter ring with a male connector pin terminal  54 . A female pin terminal  56  is attached to one end of a wire  58  and designed to engage with the male connector pin terminal  54 . A ring terminal or other connector  60  is attached to or formed on the other end of the wire  58 . The ring terminal  60  would be connected, such as with a screw or bolt, to the pressure washer unit, thus completing the path to ground. 
         [0015]    In addition to preventing start of the powered pressure washer in a dry condition, the device  10  also serves to protect a powered pressure from low pressure water conditions that might occur while the pressure washer is running. For example, if a there is ice within the supply hose or the supply hose becomes kinked such that the flow of water to the pressure washer is reduced, the pressure switch will sense the drop in pressure and stop the pressure washer. This feature (e.g., low pressure washer stall) also provides for test of an installed device  10  to ensure that the device is properly functioning to disable the pressure washer from starting or operating in low water pressure conditions. 
         [0016]    Referring to  FIG. 2 , an alternate switch system  100  to disengage the ignition system is shown. In this embodiment of the invention, the switch controls the power to the spark plug electrode. the pressure sensor or switch  102  includes a tube  104  that connects to a tap  106 . The tap  106  preferably includes barbs or an alternate device for securing the tube onto the tap such that there is fluid communication from the central body  12  through the tap  106  and into the tube  104  for water to flow. The opposite end of the tube  104  connects the a sealed piston  108  mounted within a pressure switch housing  110 . Upon the fluid in the tube reaching a threshold pressure, the piston  108  expands into the housing  110 . 
         [0017]    Located within the housing  110  is a switch mechanism  112  that includes a first electrical line  114  with a first end  116  forming an incoming electrode for connecting with a spark plug wire and a second end  118  forming a contact within the housing. A second electrical line  120  includes a first end  122  forming an outgoing electrode for connecting to a spark plug, and a second end  123  connected to a spring biased switch plate  124 . A spring  126  biases the switch plate  124  out of contact with the second end  118  of the first electrical line  114 . The spring force is preferably about 10 lb-force. The piston  108  is positioned adjacent to the switch plate such that pressurization of the piston forces the piston to force the switch plate  124  into contact with the second end  118 , thereby connecting the first electrode with the second electrode and providing power to the system as described previously. When water pressure in the tube falls below a threshold, the piston transitions away from the housing, disengaging the switch plate from the contact and cutting off the connect between the ignition and the spark plug. 
         [0018]    The foregoing describes the invention in terms of embodiments foreseen by the inventor for which an enabling description was available, notwithstanding that insubstantial modifications of the invention, not presently foreseen, may nonetheless represent equivalents thereto.