Abstract:
A filtration system for a gas powered concrete saw allows the user to inspect and/or determine how much dust is accumulated in the filter. In addition, manual filter cleaners are provided to allow the user to easily clean the filter without needing to open up the tool. In addition, the system is provided to deactivate the tool or notify the user if no filter is being utilized, or the filter is damaged. The system can also provide system lock out in the case of a missing or damaged filter. In addition, automatic methods are also provided to allow cleaning of the filter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/725,611, filed on Oct. 11, 2005. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to gas concrete saws, and more particularly, to a filtration system for use with a gas concrete saw. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Gas concrete saws are used in very harsh environments. Concrete saws are typically provided with a water cooling system that sprays water in the area of the concrete saw blade so that the water can cool the blade and can further reduce the amount of dust created by the sawing process. Very often, these types of concrete saws are used without the water cooling feature because of environmental “run off” issues, lack of water supply, or the extra hassle of connecting to a water supply. Without the water cooling, the tool creates a very dusty environment in which the tool must operate. Engine compression of the gas concrete saws is quickly lost if the air is not filtered before entering the engine. Therefore, most gas concrete saws are provided with filters and many have several layers of filters to clean the air. 
     There are several problems with the filtration systems in place today. These problems include the filters clogging frequently without the user having a good way of knowing how clogged the filter is. The only indication is from the performance drop off of the tool. The user has to open up the tool to clean the filter with some portions requiring tools for obtaining access to the filter. Furthermore, there are no lock-offs to prevent the user from running a tool without a filter. This can be especially important to a tool rental shop because the users may not understand the importance of the filters, and the rental tools can be permanently damaged if used improperly. 
     Accordingly, the present invention provides systems for allowing the user to inspect and/or determine how much dust is accumulated in a filter. In addition, manual filter cleaners are provided to allow the user to easily clean the filter without needing to open up the tool. In addition, the system is provided to deactivate the tool or notify the user if no filter is being utilized, or the filter is damaged. The system can also provide system lock out in the case of a missing or damaged filter. In addition, automatic methods are also provided to allow cleaning of the filter. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram of a gas concrete saw filtration system according to a first embodiment according to the principles of the present invention; 
         FIG. 2A  is a schematic diagram of a gas concrete saw filtration system according to a second embodiment according to the principles of the present invention; 
         FIG. 2B  is a schematic diagram of a gas concrete saw filtration system according to a third embodiment according to the principles of the present invention; 
         FIG. 3A  is a schematic diagram of a gas concrete saw filtration system according to a fourth embodiment according to the principles of the present invention; 
         FIG. 3B  is a schematic diagram of a gas concrete saw filtration system according to a fifth embodiment according to the principles of the present invention; 
         FIG. 4  is a schematic diagram of a gas concrete saw filtration system according to a sixth embodiment according to the principles of the present invention; 
         FIG. 5  is a schematic diagram of a gas concrete saw filtration system according to a seventh embodiment according to the principles of the present invention; 
         FIG. 6  is a schematic diagram of a gas concrete saw filtration system according to an eighth embodiment according to the principles of the present invention; 
         FIG. 7  is a side view of an exemplary concrete saw; and 
         FIG. 8  is a side view of an alternative concrete saw. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     With reference to  FIG. 7 , an exemplary concrete saw  110  is shown including a blade  112 , an engine  114 , a frame  116 , and a set of front wheels  118  and rear wheels  120 . Saw blade  112  is mounted to a spindle  122  that is selectively coupled for driving engagement with the engine  114 . An air filtration system  10  is provided for filtering the air delivered to engine  114 . Alternatively, a handheld concrete saw  210  is shown in  FIG. 8  including an engine  214 , a blade  212 , a handle  216 , and an air filtration system  10 . 
     With reference to  FIG. 1 , a gas concrete saw filtration system  10  according to the principles of the present invention will now be described. The filtration system  10  may include a filter chamber  12  made from a transparent or translucent material so that the user can see the amount of dust that is accumulating on the surface of the filter  14 . The filter chamber  12  can include an inlet  16  that is shaped such that the air is coming in at an angle generally tangential to the filter chamber  12 . The angled inlet causes the heavier particles to stay to the outside of the chamber and not clog the filter  14 . The filter  14  and filter chamber  12  are preferably provided with an axis-symmetric design, with the filter  14  being made out of a pleated material, such as paper or gore-type filter material. The filter chamber  12  should be either removable via twist-lock or clamp or could have a door that could be opened to remove the debris. 
     A manual filter cleaner  20  is provided including a knob  22  that would be accessible to the user at the top of the filter chamber  12 . The knob  22  would be attached to a shaft  23  that is attached to a “flicking” piece  24 . The flicking piece  24  can be located internally or externally to the filter. Its function is to rub against the pleats of the filter  14  and vibrate the debris loose from the filter when the knob  22  is turned and the flicking piece  24  rubs against the filter  14 . 
     According to a further embodiment, an air hose tap  26  is placed running from downstream of the filter  14 , between the filter  14  and the engine intake to the outside of the tool. Outer end  26   b  of the air hose tap  26  would have a check valve  28  that only allows air to flow from the outside of the tool to the inside. If the user wants to clean the filter, they can blow air into the hose  26  either manually or using compressed air. This would create a high pressure on the inside of the filter  14  and blow the debris off of the outside of the filter  14 . The air hose tap  26  can be utilized in combination or separate from the manual cleaner  20  described above. 
     As the filter  14  collects debris, the suction force on the inside of the filter  14  increases. The inherent changes in force can be utilized to develop filter cleanliness indicators. Even clean filters have a pressure drop. Therefore, if a user does not put a filter on the tool, or if the filter has a hole caused by damage, the suction force between the engine and where the filter should be, is very low. This principle can be used to warn the user that no filter is in place or that the filter is damaged. 
     According to one aspect of the present invention, as illustrated in  FIG. 1 , the filter  14  and its base  30  are mounted on springs  32 . A flexible rubber bellows  34  seals the airflow path from the inside of the filter  14  to the engine intake  36 . A pointer  38  is mounted to the filter base  30  and is lined up with a gauge  40  which is visible to the user. As the suction force increases due to the filter  14  getting dirtier, the springs  32  compress and the base  30  lowers. Therefore, the pointer  38  moves, and the user sees this on the indicator gauge  40 . If there&#39;s no filter or a damaged filter, less force would be on the base, and the pointer would raise to the no filter warning indicator  42 . 
     According to still a further embodiment, as shown in  FIG. 2A , a pressure tap  46  is provided in communication with the air inlet passage downstream of the filter  14 . The pressure tap  46  is attached to a gauge  48  on the outside of the tool. The higher the suction pressure, the dirtier the filter is. A really low section would indicate to the user a damaged or missing filter. 
     According to a still further embodiment as illustrated in  FIG. 2B , an electronic pressure or force sensor  50  can be placed between the base  30  and the support structure that the filter sits in. The pressure or force sensor  50  is attached to an electronic read out  52  which displays the cleanliness level, or indicates whether a damaged or missing filter-type problem occurs. 
     The same principles that are utilized for detecting filter cleanliness, a missing filter or damaged filter, can also be used to prevent the user from using the tool when the filter is missing or if the filter is damaged. With reference to  FIG. 3A , a pressure tap  60  is provided in communication with the inside of the filter  14 . The tap  60  is attached to a piston cylinder  62  having a movable piston  64  disposed therein with an opposing spring  66 . If the suction downstream of the filter  14  is too low (filter missing or damaged), the spring  66  will keep the locking pin (piston)  64  engaged. If locking pin  64  is engaged, the gas concrete saw is deactivated by, for example, preventing the trigger from being pulled, preventing the wheel from rotating, or preventing spark from firing, or other means that would disable the concrete saw from operating. 
     With reference to  FIG. 3B , an alternative embodiment is shown in which an electronic sensor indicator  70  is piped between the filter support  30  and the base that the filter sits on. The sensor  70  has the ability to detect a low suction force due to the absence of, or a damaged, filter. Electronic control system  72  can be utilized to prevent the gas concrete saw from operating such as by preventing the trigger from being pulled, the wheel from rotating, preventing the spark from firing or by other known methods of preventing operation of the gas concrete saw. 
     With reference to  FIG. 4 , another alternative of preventing operation of the gas concrete saw with a missing or damaged filter is provided. According to this embodiment, the filter  14  and base  30  are mounted on springs  32  with a rubber bellows  34  sealing the airflow path from the inside of the filter  14  to the engine intake  36 . A locking pin  80  is mounted to the base filter  30 . If the suction is too low (filter missing or damaged) the springs  32  will keep the locking pin  80  in an engaged position. If the locking pin is in the engaged position, it prevents proper operation of the gas concrete saw by, for example, preventing the trigger from being pulled, preventing the wheel from rotating, or preventing spark from firing depending on the mechanical design of the gas concrete saw. 
     The saw filtration system  10 , as illustrated in  FIG. 1 , can also be provided within an automatic filter cleaning mechanism. As shown in  FIG. 1 , a gear  84  is added to the shaft  23  of the flicker  24  and a rack  86  is provided on a surface  36  of the engine inlet. As the suction increases inside the filter  14 , the increased suction causes the base  30  to lower, the lowering of the base  30  causes the gear  84  to turn. The turning gear  84  causes the flicker to rotate and the filter is cleaned automatically. As the filter collects debris, the suction force increases, pulling the base of the filter and filter housing downward. The gear rides against a fixed rack, rotating the gear. The gear is fixed to the shaft of the flicker and the flicker rotates. A flexible shaft  23 , universal joint, or bevel gear set may be required to translate the vertical rotational motion into a horizontal rotational motion. In the case of a flexible shaft  23 , a rigid sheath  85  is required to hold the gear  84  in engagement with the rack  86 . 
     If the base  30  of the filter  14  drops too slowly to effectively rotate the flicker  24 , a push button cleaning method can be employed. As the base  30  drops, a latch system  90  holds the springs  32  in a compressed state. When the engine is turned off, no suction force would be pulling the filter  14  and base  30  down. At this time, the user can push a button  92 , which releases the latch  90  and the springs  32  push the base  30  upwards. As the base  30  gets pushed upwards, the gear  84  rises against the rack  86 , and the flicker  24  rotates, cleaning off the filter  14 . 
     With reference to  FIG. 5 , an air tap cleaner will now be described for providing an automatic cleaning of the filter  14 . An air tap  100  is placed inside of the filter  14  (between the filter and the engine). The air tap  100  is ducted to the motor cooling fan area  102 . During normal operation, a plug  104  in the tap  100  prevents air from entering the tap  100 . When the user wishes to clean the filter  14 , they would go to a clean area (no dust in the air), and remove the plug  104  in the line  100 . This would force pressurized air generated by the motor cooling fan  102  to pass from inside to outside of the filter  14 , cleaning the filter  14 . 
     With reference to  FIG. 6 , a radial fan/governor automatic cleaning system will now be described. As illustrated in  FIG. 6 , a fan  110  is mounted to the filter canister  12 . A plurality of pendulum masses  112  are hung from the fan  110  in a manner that they rest against the pleats of the filter  14 . Springs  114  can be used to bias the pendulums into the filter  14 . The fan  110  is positioned so that the inlet air through passage  16  causes the fan  110  to rotate. When the filter  14  is clean, the volume flow of air into the chamber is high. Therefore, the fan  110  rotates quickly, and the pendulum&#39;s  112  inertia will be larger than the spring force, and the pendulums will move outwards away from the pleats of the filter  14 . As the filter  14  clogs, the airflow will decrease. The decreased airflow will cause the fan  110  to slow down and the springs  114  will overcome the inertial force of the pendulums  112 . The pendulums  112  will come in and remove the debris off of the pleats of the filter  14 . A derivation of this would be to keep the pendulums  112  in contact with the filter  14  at all times to prevent the build-up of debris on the filter  14 . 
     Each of the above concepts can be used by themselves or in combination, or as one stage in a multi-stage filter system. The above concepts contribute to extending the time between filter cleanings or make it easier to clean the filters. The systems also provide the user with visual indicators of the filter presence, cleanliness, or damage level. The systems also allow the user to clean the filter without opening up the tool. The systems of the present invention also warn and prevent the user from using the gas concrete saw without a proper filter in place. This can be especially important to a tool rental shop because the users may not understand the importance of the filter. The system of the present invention also provides methods of automatically cleaning the filter so that the user does not need to take any action in cleaning the filter. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.