Abstract:
A cleaning system for a lighting surface of a vehicle having a brake system comprising at least one tank of pressurized air, comprising at least one accumulator, a bleed valve assembly, at least one nozzle assembly, and a control valve assembly. Operation of the control valve assembly selectively allows and prevents pressurized air within the accumulator to flow to the at least one nozzle assembly. The bleed valve assembly controls the flow of air from the at least one tank of pressurized air to the at least one accumulator such that flow of pressurized air from the accumulator to the at least one nozzle assembly does not adversely affect operation of the brake system.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. Provisional Patent Application Ser. No. 60/937,478 filed Jun. 27, 2007, the contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to cleaning systems and methods for removing foreign substances from lighting surfaces on vehicles and, more specifically, to cleaning systems and methods adapted to use pressurized air from the air brake system of the vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vehicles are often used in environments in which surfaces of the vehicles are at least partly covered with a foreign substance. For example, a logging truck may be used in a wet environment where mud splatters onto the fenders and other surfaces of the vehicle. As another example, a tractor trailer rig may be used in a cold, wet environment in which snow and/or ice can collect on the bumper or grill of the moving vehicle. 
         [0004]    For many surfaces, the accumulation of foreign substance is simply an aesthetic and/or aerodynamic performance issue. Problems can arise, however, when foreign substances accumulate on lighting surfaces of a vehicle. For the purposes of this application, the term “lighting surface” refers to a surface, typically transparent or translucent, of a light bulb, lens, or the like that is exposed to the elements and through which light shines. Foreign substances on lighting surfaces can prevent light from passing through the lighting surface. 
         [0005]    Cleaning systems for removing foreign substances from lighting surfaces are known; these systems may be mechanical (wipers) or employ pressurized fluids such as air and/or liquids. The present invention relates to cleaning systems for removing foreign substances from lighting surfaces that employ a stream of pressurized fluid to remove foreign substances from lighting surfaces. 
         [0006]    While the principles of the present invention may be applied to any vehicle, the present invention is of particular significance in the context of a vehicle that employs an air brake system. As is well-known, a vehicle having an air brake system typically employs an air compressor, air brake assemblies at each wheel, and a tank of pressurized air arranged adjacent to each air brake assembly. Conduits carry pressurized air from the compressor to the air tanks. When the brakes are applied, the pressurized air stored in the tanks actuates the air brake assemblies. While the pressurized air within the air brake system is suitable for use in a cleaning system for removing foreign substances from lighting surfaces, clearly the operation of the air brake system cannot be adversely affected. 
         [0007]    The need thus exists for cleaning systems and methods for removing foreign substances from lighting surfaces of a vehicle that employ pressurized air from the air brake system of the vehicle without adversely affecting the operation of the air brake system. 
       RELATED ART 
       [0008]    The following related references were uncovered by a professional patentability search conducted on behalf of the Applicant. 
         [0009]    U.S. Pat. No. 5,546,630 to Long discloses a pneumatic cleaning system that directly ties into the pressure tank of a pneumatic braking system. This system does not isolate the cleaning system from the braking system. 
         [0010]    U.S. Pat. No. 5,657,929 to DeWitt et al. discloses a system that directs both pressurized air and pressurized liquids from different nozzles onto a surface to be cleaned. This patent discloses the use of an existing auxiliary air source or of a dedicated compressor as the source of pressurized air. This system does not use pressurized air from an existing pneumatic braking system. 
         [0011]    U.S. Pat. No. 6,554,210 to Holt et al. discloses a jet assembly through which both pressurized air from one source and pressurized fluid from another source can be sprayed onto a surface to be cleaned. 
         [0012]    U.S. Pat. No. 5,140,719 to Cowan discloses a system for directing pressurized air onto a windshield. 
         [0013]    U.S. Pat. No. 1,448,508 to Thum, U.S. Pat. No. 3,169,676 to Hanselmann, U.S. Pat. No. 4,026,468 to Tinder, U.S. Pat. No. 4,248,383 to Savage, U.S. Pat. No. 4,324,363 to Rauen, Jr., U.S. Pat. No. 4,505,001 to Fasolino, U.S. Pat. No. 5,083,339 to Bristow, and U.S. Pat. No. 6,077,361 to Glenn all disclose systems that direct liquids or mixtures of liquids and pressurized air onto a surface to be cleaned. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention may be embodied as a cleaning system for a lighting surface of a vehicle having a brake system comprising at least one tank of pressurized air, comprising at least one accumulator, a bleed valve assembly, at least one nozzle assembly, and a control valve assembly. Operation of the control valve assembly selectively allows and prevents pressurized air within the accumulator to flow to the at least one nozzle assembly. The bleed valve assembly controls the flow of air from the at least one tank of pressurized air to the at least one accumulator such that flow of pressurized air from the accumulator to the at least one nozzle assembly does not adversely affect operation of the brake system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a somewhat schematic top plan view of a portion of a vehicle incorporating a first example cleaning system for removing foreign substances from lighting surfaces of the vehicle constructed in accordance with the principles of the present invention; 
           [0016]      FIG. 2  is a rear elevation view of a nozzle portion of the first example cleaning system; 
           [0017]      FIG. 3  is a schematic illustration of the first example cleaning system; 
           [0018]      FIG. 4  is a schematic illustration of a second example cleaning system of the present invention; and 
           [0019]      FIG. 5  is a schematic illustration of a third example cleaning system of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The principles of the present invention may be applied in a number of configurations, and three examples of those configurations will be described separately below. 
       I. First Example 
       [0021]    Referring initially to  FIG. 1  of the drawing, depicted therein is a first example cleaning system  20  constructed in accordance with, and embodying, the principles of the present invention. The first example cleaning system  20  is configured to remove foreign substances from first, second, third, and fourth lighting surfaces  22   a,    22   b,    22   c,  and  22   d  of a vehicle  24 . In particular, the lighting surfaces  22   a,    22   b,    22   c,  and  22   d  are formed by lenses of light assemblies  25   a,    25   b,    25   c,  and  25   d  forming a part of the vehicle  24 . 
         [0022]    The vehicle  24  is or may be conventional and will be described herein only to the extent necessary for a complete understanding of the present invention; only a portion of the vehicle  24  is depicted in  FIG. 1 . 
         [0023]    The example vehicle  24  comprises a vehicle frame  30 , first and second axles  32   a  and  32   b,  first and second air tanks  34   a  and  34   b,  and first, second, third, and fourth wheel assemblies  36   a,    36   b,    36   c,  and  36   d.  The vehicle frame  30  is used herein to refer to the rigid frame structure of the vehicle  24 . The vehicle  24  further comprises a rear bumper structure  38 , and the example light assemblies  25  are mounted to the bumper structure  38 . 
         [0024]    The air tanks  34  form part of an air brake system (not shown in its entirety) for inhibiting rotation of the wheel assemblies  36 . The air brake system is or may be conventional and will not be described herein beyond that extent necessary for a complete understanding of the present invention. 
         [0025]    As shown in  FIGS. 1 and 3 , the first example cleaning system  20  comprises an accumulator  40 , a bleed valve assembly  42 , a control valve assembly  44 , first and second nozzle assemblies  46   a  and  46   b,  and a control switch  48  ( FIG. 3 ). The accumulator  40  is operatively connected to the second air tank  34   b  through the bleed valve assembly  42 , while the accumulator  40  is operatively connected to the nozzle assemblies  46   a  and  46   b  through the control valve assembly  44 . The bleed valve assembly  42  is a regulated valve that defines a predetermined minimum pressure value as will be described in detail below. 
         [0026]      FIG. 3  also shows that the control valve assembly  44  comprises a valve  50 , a timer relay  52 , and an actuator  54 . The valve  50  is a mechanical component that operates in an OPEN state or a CLOSED state; connected as shown in  FIG. 3 , the valve  50  allows fluid flow between the accumulator  40  and the nozzle assemblies  46  when in the OPEN state and prevents such fluid flow when in the CLOSED state. 
         [0027]    The timer relay  52  is an electrical component that, after a first delay period after receipt of an input signal, generates a timer output signal for a second delay period. In the example cleaning system  20 , the duration of the delay periods are settable. In one example, the timer output signal is normally in a LOW state; when the timer relay  52  is triggered by the input signal, after the first delay period the timer relay  52  causes the timer output signal to go into a HIGH state for a the second delay period. 
         [0028]    The example actuator  54  is an electro-mechanical component that, when connected between the timer relay  52  and the valve  50  as shown in  FIG. 3 , places the valve  50  in either the OPEN state or the CLOSED state depending upon the state of the timer output signal. In the example described herein, the actuator  54  places the valve  50  in the CLOSED state when the timer output signal is in the LOW state and places the valve  50  in the OPEN state for as long as the timer output signal is in the HIGH state. 
         [0029]      FIG. 3  also shows that the control switch  48  is operatively connected to the control valve assembly  44 . The position of the control switch  48  determines whether the control valve assembly  44  allows fluid flow from the accumulator  40  to the nozzle assemblies  46 . In particular, the example control switch  48  is connected as the input to the timer relay  52  to generate the input signal in response to which the timer relay  52  generates the timer output signal. In one example, the control switch  48  is a momentary switch that, when operated, generates a pulse. In this case, the control switch  48  is a dedicated switch under control of an operator of the vehicle  24 . Preferably, however, the control switch  48  is tied to or forms a part of an ignition circuit of the vehicle  24 . In this preferred case, the control switch  48  generates control signal when the vehicle ignition circuit is in its “ON” position. 
         [0030]    The example timer relay  52  contains first and second separate timer circuits. First and second delay periods are associated with the first and second timer circuits, respectively. Upon receiving the control signal generated by the control switch  48 , the timer relay  52  generates waits for the first time period and then generates the timer output signal in the HIGH state for the second delay period. For as long as the control switch  48  is “ON” (generates the control signal), at the end of every first delay period the timer relay  52  generates the timer output signal in the HIGH state for the second delay period. 
         [0031]      FIG. 3  further shows that the control valve assembly  44  is connected to a T-fitting  56  that allows fluid communication between the actuator  54  and the first and second nozzle assemblies  46   a  and  46   b.    
         [0032]      FIG. 1  illustrates that example cleaning system  20  further comprises a mounting frame  60  that is rigidly connected to the vehicle frame  30 . The accumulator  40  and control valve assembly  44  are rigidly attached to the mounting frame  60 .  FIGS. 1 and 2  illustrate that the first and second nozzle assemblies  46  are rigidly connected to the vehicle bumper  38  such that fluid  62  exiting then nozzle assemblies  46  is directed at the lighting surfaces  22 . 
         [0033]    As perhaps best shown with reference to  FIG. 3 , the example cleaning system  20  comprises a number of conduits to connect the various components described above in a conventional manner. In particular, a first conduit  70  is connected between the air tank  34   b  and the bleed valve assembly  42 . A second conduit  72  is connected between the bleed valve assembly  42  and the accumulator  40 . A third conduit  74  is connected between the accumulator  40  and the control valve  50 . A fourth conduit  76  is connected between the control valve  50  and the T-fitting  56 . Fifth and sixth conduits  78   a  and  78   b  are connected between the T-fitting  56  and the first and second nozzle assemblies  46   a  and  46   b,  respectively. 
         [0034]    The conduits  70 - 78  all are or may be conventional piping with associated fittings, seals, and the like capable of conveying pressurized air as discussed herein. In the example system  20 , the first and second conduits  70  and  72  are ¼″ lines such as pipes or hoses, the third conduit  74  is a ¾″ line, and the fourth, fifth, and sixth conduits  76 ,  78   a,  and  78   b  are ½″ lines such as pipes or hoses. 
         [0035]    The example cleaning system  20  operates basically as follows. When the ignition circuit of the vehicle is placed in the “ON” condition, the brake system operates in a normal manner. During normal operation of the brake system, the air tanks  34   a  and  34   b  fill up with pressurized air. 
         [0036]    Once the pressure within the air tanks  34   a  and  34   b  is above a predetermined minimum pressure level, the bleed valve assembly  42  allows air to flow from the second air tank  34   b  to the accumulator  40 . The bleed valve assembly  42  closes if the pressure within the air tanks  34   a  and  34   b  falls below the predetermined minimum pressure level. In the example system  20 , the predetermined minimum pressure value is approximately 80 lbs but in any event is within a range of 80-90 lbs. In addition, the bleed valve assembly  42  and first and second conduits  70  and  72  are sized and dimensioned to allow only a small amount of air flow between the air tank  34   b  and the accumulator  40 . 
         [0037]    Once the accumulator  40  is filled with pressurized air, the accumulator  40  stores the pressurized air until the cleaning system  20  is operated. When the ignition system is turned on, the control switch  48  is placed in the “ON” position. The control switch  48  triggers the timer circuit  52 ; after the first delay period, the timer circuit  52  causes the actuator circuit  54  to open the valve  50  for the second delay period. This process is repeated for as long as the switch  48  is on. 
         [0038]    When the valve  50  is open, pressurized air flows from the accumulator  40  to the T-fitting  56  and through the T-fitting  56  to the first and second nozzle assemblies  46   a  and  46   b.  As perhaps best shown by  FIGS. 2 and 3 , the nozzle assemblies  46   a  and  46   b  each comprise a nozzle body  80  in which are formed a number of nozzle openings  82 . The pressurized air flowing into the nozzle assemblies  46  flows into the nozzle bodies  80  and out of the nozzle openings  82 . 
         [0039]    Each nozzle body  80  is arranged such that nozzle openings  82  thereof are directed at one of the lighting surfaces  22 . Accordingly, the pressurized air flowing out of each of the nozzle openings  82  impinges on the associated lighting surface  22  in the form of streams  84  as shown in  FIG. 2 . The streams  84  of pressurized air at least partly remove debris from the lighting surfaces  22 . 
       II. Second Example 
       [0040]    Referring now to  FIG. 4  of the drawing, depicted therein is a second example cleaning system  120  constructed in accordance with, and embodying, the principles of the present invention. Like the first example cleaning system  20 , the second example cleaning system  120  is configured to remove foreign substances from the lighting surfaces of a vehicle such as the vehicle  24  described above. The vehicle is or may be conventional and will not be described again. 
         [0041]    As shown in  FIG. 4 , the first example cleaning system  120  comprises an accumulator  130 , a bleed valve assembly  132 , a control valve assembly  134 , first and second nozzle assemblies  136   a  and  136   b,  and a control switch  138 . The second example cleaning system  120  further comprises a reservoir  140  and a check valve  142 . The bleed valve assembly  132  is a regulated valve that defines a predetermined minimum pressure value as will be described in detail below. 
         [0042]    The accumulator  130  is operatively connected to the second air tank  34   b  through the bleed valve assembly  132 , while the accumulator  130  is operatively connected to the nozzle assemblies  136   a  and  136   b  through the control valve assembly  134 . The reservoir  140  is operatively connected to the nozzle assemblies  136   a  and  136   b  through the check valve  142 . The reservoir  140  stores cleaning liquid, and the check valve  142  is arranged such that the cleaning liquid is allowed to flow only out of the reservoir  140  and pressurized air cannot flow into the reservoir  140 . 
         [0043]      FIG. 4  also shows that the control valve assembly  134  comprises a valve  150 , a timer relay  152 , and an actuator  154 . The valve  150  is a mechanical component that operates in an OPEN state or a CLOSED state; connected as shown in  FIG. 4 , the valve  150  allows fluid flow between the accumulator  130  and the nozzle assemblies  136  when in the OPEN state and prevents such fluid flow when in the CLOSED state. 
         [0044]    The timer relay  152  is an electrical component that, after a first delay period after receipt of an input signal, generates a timer output signal for a second delay period. In the example cleaning system  120 , the duration of the first and second delay periods are settable. In one example, the timer output signal is normally in a LOW state; when the timer relay  152  is triggered by the input signal, the timer relay  152  waits for the first delay period (e.g., 15 minutes) and then causes the timer output signal to go into a HIGH state for a period of time equal to the delay period (e.g., 5 seconds). 
         [0045]    The example actuator  154  is an electro-mechanical component that, when connected between the timer relay  152  and the valve  150  as shown in  FIG. 4 , places the valve  150  in either the OPEN state or the CLOSED state depending upon the state of the timer output signal. In the example described herein, the actuator  154  places the valve  150  in the CLOSED state when the timer output signal is in the LOW state and places the valve  150  in the OPEN state for as long as the timer output signal is in the HIGH state. 
         [0046]      FIG. 4  also shows that the control switch  138  is operatively connected to the control valve assembly  134 . The position of the control switch  138  determines whether the control valve assembly  134  allows fluid flow from the accumulator  130  to the nozzle assemblies  136 . In the example system  120 , the control switch  138  is connected to the ignition circuit of the vehicle  24  and thus is on when the ignition circuit is in the ON position. 
         [0047]    In particular, after waiting for the first delay period after the leading edge of the pulse is generated by the control switch  138 , the timer relay  152  generates the timer output signal in the HIGH state for the second delay period. 
         [0048]      FIG. 4  further shows that the control valve assembly  134  is connected to a first T-fitting  156  that allows fluid communication between the actuator  154  and the first and second nozzle assemblies  136   a  and  136   b.  The control valve assembly  134  is further operatively connected to a second T-fitting  158  that allows fluid communication between the reservoir  140  and the nozzle assemblies  136   a  and  136   b.    
         [0049]    As perhaps best shown with reference to  FIG. 4 , the example cleaning system  120  comprises a number of conduits to connect the various components described above in a conventional manner. In particular, a first conduit  160  is connected between the air tank  34   b  and the bleed valve assembly  132 . A second conduit  162  is connected between the bleed valve assembly and the accumulator  130 . A third conduit  164  is connected between the accumulator  130  and the control valve  150 . 
         [0050]    A fourth conduit  166  is connected between the control valve  150  and the second T-fitting  158 . A fifth conduit  168  is connected between the first T-fitting  156  and the second T-fitting  158 . Sixth and seventh conduits  170   a  and  170   b  are connected between the first T-fitting  156  and the first and second nozzle assemblies  136   a  and  136   b,  respectively. An eighth conduit  172  is connected between the reservoir  140  and the check valve  142 , while a ninth conduit  174  is connected between the check valve  142  and the second T-fitting  158 . 
         [0051]    The conduits  160 - 174  all are or may be conventional piping with associated fittings, seals, and the like capable of conveying pressurized air as discussed herein. In the example system  120 , the first and second conduits  160  and  162  are ¼″ lines such as pipes or hoses, while the third conduit  164  is a ¾″ line. The fourth, fifth, sixth, and seventh conduits  166 ,  168 ,  170   a,  and  170   b  are ½″ lines such as pipes or hoses. The eighth and ninth conduits  172  and  174  are ¼″ lines such as pipes or hoses. 
         [0052]    The example cleaning system  120  operates basically as follows. The brake system operates normally when the ignition system is placed in the ON configuration. During normal operation of the brake system, the air tanks fill up with pressurized air. The bleed valve assembly  132  opens to allow air to flow from the second air tank to the accumulator  130  when the air pressure within the air tanks is above a predetermined minimum value. If the pressure of the air within the tanks falls below the predetermined minimum value, the bleed valve assembly  132  closes. In the example system  120 , the predetermined minimum pressure value is approximately 80 lbs but in any event is within a range of 80-90 lbs. In addition, the bleed valve assembly  132  and first and second conduits  160  and  162  are sized and dimensioned to allow only a small amount of air flow between the air tank  34   b  and the accumulator  130 . 
         [0053]    Once the accumulator  130  is filled with pressurized air, the accumulator  130  stores the pressurized air until operation of the cleaning system  120  is required. To actuate the cleaning system  120 , the user activates the control switch  138 ; in this case, the control switch  138  is operated by turning on the vehicle ignition. The control switch  138  triggers the timer circuit  152 , which after the first delay period causes the actuator circuit  154  to open the valve  150  for the second delay period. 
         [0054]    When the valve  150  is open, pressurized air flows from the accumulator  130  to the second T-fitting  158  and then to the first T-fitting  156 . The pressurized air flowing through the second T-fitting  158  draws fluid out of the reservoir  140  through the check valve  142 . The fluid drawn from the reservoir  140  is mixed with the pressurized air in the second T-fitting  158 . The mixture of pressurized air and liquid is then carried through the first T-fitting  156  and to the first and second nozzle assemblies  136   a  and  136   b.    
         [0055]    Like the nozzle assemblies  46  described above, the nozzle assemblies  136   a  and  136   b  each comprise a nozzle body  180  in which are formed a number of nozzle openings  182 . The pressurized mixture flowing into the nozzle assemblies  136  flows into the nozzle bodies  180  and out of the nozzle openings  182 . 
         [0056]    Each nozzle body  180  is arranged such that nozzle openings  182  thereof are directed at one of the lighting surfaces on the vehicle. Accordingly, the pressurized mixture flowing out of each of the nozzle openings  182  impinges on the associated lighting surface  22  in the form of streams similar to those depicted in  FIG. 2 . The streams of pressurized mixture at least partly remove debris from the lighting surfaces at which the nozzle openings  182  are directed. 
       III. Third Example 
       [0057]    Referring now to  FIG. 5  of the drawing, depicted therein is a third example cleaning system  220  constructed in accordance with, and embodying, the principles of the present invention. Like the first and second example cleaning systems  20  and  120 , the third example cleaning system  220  is configured to remove foreign substances from the lighting surfaces of a vehicle such as the vehicle  24  described above. The vehicle is or may be conventional and will not be described again. 
         [0058]      FIG. 5  illustrates that the nozzle assemblies  46   a  and  46   b  described above may be used as part of the third example cleaning system  220 . The example nozzle assemblies  46  will not be described again herein.  FIG. 5  further schematically illustrates a cab area  222  of the vehicle on which the cleaning system  220  is mounted. 
         [0059]    As shown in  FIG. 5 , the third example cleaning system  220  comprises an accumulator  230 , a bleed valve assembly  232 , a control valve assembly  234 , a remote control switch  236 , and a local control switch  238 . The bleed valve assembly  232  is a regulated valve that defines a predetermined minimum pressure value as will be described in detail below. The remote control switch  236  is located in the cab area  222  of the vehicle. 
         [0060]    The accumulator  230  is operatively connected to the second air tank  34   b  through the bleed valve assembly  232 , while the accumulator  230  is operatively connected to the nozzle assemblies  46   a  and  46   b  through the control valve assembly  234 . 
         [0061]      FIG. 5  also shows that the control valve assembly  234  comprises a valve  240 , a timer relay  242 , an actuator  244 , a housing  246 , and T-fitting  248 . The valve  240  is a mechanical component that operates in an OPEN state or a CLOSED state; connected as shown in  FIG. 5 , the valve  240  allows fluid flow between the accumulator  230  and the nozzle assemblies  46  when in the OPEN state and prevents such fluid flow when in the CLOSED state. 
         [0062]    The timer relay  242  is an electrical component that, after a first delay period after receipt of an input signal, generates a timer output signal for a second delay period. In the example cleaning system  220 , the duration of the first and second delay periods are settable. In one example, the timer output signal is normally in a LOW state; when the timer relay  242  is triggered by the input signal, the timer relay  242  waits for the first delay period (e.g., 15 minutes) and then causes the timer output signal to go into a HIGH state for a period of time equal to the delay period (e.g., 5 seconds). 
         [0063]    The example actuator  244  is an electro-mechanical component that, when connected between the timer relay  242  and the valve  240  as shown in  FIG. 5 , places the valve  240  in either the OPEN state or the CLOSED state depending upon the state of the timer output signal. In the example described herein, the actuator  244  places the valve  240  in the CLOSED state when the timer output signal is in the LOW state and places the valve  240  in the OPEN state for as long as the timer output signal is in the HIGH state. 
         [0064]      FIG. 5  also shows that the remote control switch  236  and the local control switch  238  are operatively connected to the control valve assembly  234 . The position of the control switches  236  and  238  determines whether the control valve assembly  234  allows fluid flow from the accumulator  230  to the nozzle assemblies  46 . 
         [0065]    In the example system  220 , the remote control switch  236  is located in the cab area  222  and is connected to the ignition circuit of the vehicle  24  and thus is operative when the ignition circuit is in the ON position. In the example system  220 , the local control switch  238  is mounted on the control housing  246 . The local control switch  238  is operative whenever the control valve assembly  234  is energized and may be operated by an operator standing near the control housing  246 , which will typically be spaced a significant distance from the cab area  222 . 
         [0066]    Actuation of either the remote control switch  236  or the local control switch  238  causes a pulse to be generated. After waiting for the first delay period after the leading edge of the pulse generated by either the remote control switch  236  or the local control switch  238 , the timer relay  242  generates the timer output signal in the HIGH state for the second delay period. 
         [0067]      FIG. 5  further shows that the control valve assembly  234  is connected to the T-fitting  248  to allow fluid communication between the actuator  244  and the first and second nozzle assemblies  46   a  and  46   b.    
         [0068]      FIG. 5  further illustrates that the example cleaning system  220  comprises a number of conduits to connect the various components described above in a conventional manner. In particular, a first conduit  250  is connected between the air tank  34   b  and the bleed valve assembly  232 . A second conduit  252  is connected between the bleed valve assembly and the accumulator  230 . A third conduit  254  is connected between the accumulator  230  and the control valve  240 . 
         [0069]    A fourth conduit  256  is connected between the control valve  240  and the T-fitting  248 . Fifth and sixth conduits  258   a  and  258   b  are connected between the T-fitting  248  and the first and second nozzle assemblies  46   a  and  46   b,  respectively. 
         [0070]    The conduits  250 - 258  all are or may be conventional piping with associated fittings, seals, and the like capable of conveying pressurized air as discussed herein. In the example system  220 , the first and second conduits  250  and  252  are ¼″ lines such as pipes or hoses, while the third conduit  254  is a ¾″ line. The fourth, fifth, and sixth conduits  256 ,  258   a,  and  258   b  are ½″ lines such as pipes or hoses. 
         [0071]    The example cleaning system  220  operates basically as follows. The brake system  220  operates normally when the ignition system is placed in the ON configuration. During normal operation of the brake system, the air tanks fill up with pressurized air. A ball valve  260  may be arranged to prevent air flow between the tanks  34   b  and  230 . 
         [0072]    The bleed valve assembly  232  opens to allow air to flow from the second air tank to the accumulator  230  when the air pressure within the air tanks is above a predetermined minimum value. If the pressure of the air within the tanks falls below the predetermined minimum value, the bleed valve assembly  232  closes. In the example system  220 , the predetermined minimum pressure value is approximately 80 lbs but in any event is within a range of 80-90 lbs. In addition, the bleed valve assembly  232  and first and second conduits  250  and  252  are sized and dimensioned to allow only a small amount of air flow between the air tank  34   b  and the accumulator  230 . 
         [0073]    Once the accumulator  230  is filled with pressurized air, the accumulator  230  stores the pressurized air until operation of the cleaning system  220  is required. To actuate the cleaning system  220 , the user activates one of the control switches  236  and  238 . The remote control switch  236  may be operated simply by turning on the vehicle ignition or may be a discrete switch separate from the ignition system. The local control switch  238  will be independent of the ignition system and will allow an operator standing near the nozzle assemblies  46   a  and/or  46   b  to operate the cleaning system  220 . In either case, the control switches  236  and/or  238  triggers the timer circuit  242 , which after the first delay period causes the actuator circuit  244  to open the valve  240  for the second delay period. 
         [0074]    When the valve  240  is open, pressurized air flows from the accumulator  230  to the first T-fitting  248 . The pressurized air is then carried through the first T-fitting  248  and to the first and second nozzle assemblies  46   a  and  46   b.  The nozzle assemblies  46  operate to clean surfaces to which they are directed as generally described above. 
       IV. Summary 
       [0075]    In the foregoing examples, the example cleaning systems  20 ,  120  and  220  are arranged to remove foreign substances from a plurality of lighting surfaces associated with rear lights of the vehicle  24 . The cleaning systems  20 ,  120 , and  220  can be configured to remove foreign substances from additional lighting surfaces, or a separate cleaning system may be connected to an air tank at another location on the vehicle. 
         [0076]    Accordingly, the example cleaning systems  20 ,  120 , and  220  may be configured to remove foreign substances from other light transmitting or reflecting surfaces on the vehicle such as a windshield, headlights, turn signals, and/or rear view mirrors. With any of these lighting surfaces, foreign substances can accumulate on the surface and interfere with light passing through or reflecting off of the surface. 
         [0077]    The scope of the present invention should thus be determined by the following claims and not the foregoing detailed description of the invention.