Patent Publication Number: US-8123148-B2

Title: Vehicle windshield cleaning system

Description:
RELATE BACK 
     The present application is a divisional application claiming priority from pending U.S. patent application Ser. No. 11/928,738 entitled “Vehicle Windshield Cleaning System” and also claims priority from provisional application Ser. No. 60/952,036 and is a continuation in part of co-pending application Ser. No. 11/341,116 filed Jan. 27, 2006 which is a continuation in part of application Ser. No. 10/894,266, filed Jul. 19, 2004 (claiming priority from provisional application 60/551,571), which is a continuation in part of application ser. No. 10/653,827 filed on Sep. 3, 2003, now U.S. Pat. No. 6,902,118 which is a continuation in part of U.S. Ser. No. 10/269,647 filed Oct. 11, 2002 (claiming priority from U.S. provisional application 60/415,552), now U.S. Pat. No. 6,851,624, all of which are incorporated herein by reference and from which priority is claimed. 
     The present application claims priority from provisional application Ser. No. 60/952,036 and is a continuation in part of co-pending application Ser. No. 11/341,116 filed Jan. 27, 2006 which is a continuation in part of application Ser. No. 10/894,266, filed Jul. 19, 2004 (claiming priority from provisional application 60/551,571), which is a continuation in part of application Ser. No. 10/653,827 filed on Sep. 3, 2003, now U.S. Pat. No. 6,902,118 which is a continuation in part of U.S. Ser. No. 10/269,647 filed Oct. 11, 2002 (claiming priority from U.S. provisional application 60/415,552), now U.S. Pat. No. 6,851,624, all of which are incorporated herein by reference and from which priority is claimed. 
    
    
     FIELD OF THE INVENTION 
     The present invention concerns a windshield cleaning system, and more particularly to a windshield cleaning system that heats cleaning fluid applied to the windshield. 
     BACKGROUND ART 
     U.S. Pat. No. 6,364,010 entitled “Device to Provide Heated Washer Fluid” to Richman et al. concerns an apparatus and method for improving the cleaning and deicing effectiveness of a washer fluid in a motor vehicle before spraying it against a windshield, headlamps, etc, and utilizes the heat from the engine coolant to elevate the temperature of the washer fluid. U.S. Pat. Nos. 5,957,384 and 6,032,324 also concern de-icing of a windshield. 
     SUMMARY OF THE INVENTION 
     The invention concerns apparatus and method for providing a large amount of heated cleaning fluid to a vehicle surface. An exemplary system has an inlet port for receiving an amount of fluid; an outlet port for dispensing an amount of heated fluid; a heating element that heats up fluid passing from the inlet to the outlet; and a control circuit for energizing the heating element with a voltage to heat the fluid passing from the inlet to the outlet. 
     In one exemplary embodiment, the system provides heated cleaning fluid to a vehicle surface and includes structure defining an inlet port for receiving an amount of fluid, an outlet port in fluid communication with a reservoir for dispensing an amount of heated fluid. 
     These and other objects advantages and features of the invention will become better understood from the following detailed description of one exemplary embodiment of the present invention which is described in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematic of a representative system for use with the present invention; 
         FIG. 2  is an alternate block diagram schematic of a representative system for use with the present invention; 
         FIG. 3  is a schematic diagram of a drive circuit coupled to a fluid heating element that forms part of the  FIG. 2  system; 
         FIGS. 4-7  are schematic depictions of control circuits for use with a washer control system constructed according to an alternative embodiment of the present invention; 
         FIG. 8  is a perspective view of a heating assembly coupled to a fluid pump; 
         FIG. 9  is a plan view of an exemplary heating canister constructed in accordance with the invention; and 
         FIG. 10  is a view as seen from the line  10 - 10  in  FIG. 9 ; 
         FIGS. 11 ,  12 , and  13  depict an alternate embodiment of a fluid heating system; 
         FIGS. 14 and 15  illustrate operation of a check valve for use with the invention; and 
         FIGS. 16 and 17  are schematic diagrams of a representative system for use with the present invention as shown  FIGS. 9 and 10 . 
     
    
    
     EXEMPLARY EMBODIMENT FOR PRACTICING THE INVENTION 
     The drawings depict embodiments of the present invention that concern a washer control system  10  for use with a vehicle. In the disclosed exemplary embodiments of the invention, the control system  10  is used in conjunction with a windshield washer apparatus. The control system  10  includes a control circuit  14  that includes an electronic output drive signal circuit  20  and an input signal interpretation or conditioning circuit  16 . 
     The input signal interpretation circuit  16  electronically interfaces with at least one temperature sensor  18 . In one embodiment of the invention, the temperature sensor provides signals related to the temperature of washer fluid supplied to windshield spray nozzles on the vehicle. In one embodiment of the invention, the control system also includes an electronic output circuit that drives an output power control for at least one heating element that heats the windshield washer fluid. One exemplary control system could have both “high side” and “low side” type drives working together as illustrated in  FIG. 2 . An alternate control system is a “low side” type drive, meaning the module activates and deactivates the heater element by controlling the electrical circuit path to ground. Another alternate control system could have an output drive that is a “high side” type, meaning the module activates and deactivates the heater element by controlling the electrical circuit path to a power source. In accordance with another alternate control system, an electrical interface coupled to a vehicular communication bus allows the control system to be controlled by vehicle communications and makes data available to the vehicle for operation and diagnostics of the control system. 
     The control circuit  14  includes a programmable controller or microprocessor  14   a  that implements control algorithms for washer heater control output functions in response to vehicle input signals. As seen in the functional schematic of  FIG. 1 , the control system  10  includes an electronic output  12  from the control circuit  14  for providing controlled current to the heating element  30 . Heating element  30  may be composed of a single heating element or multiple heating elements. By selecting heater current draw and power rating the heating time and total system current draw can be modified over a wide range of operating parameters based on individual vehicle requirements, ie. electrical power available. The control circuit  14  also includes an input signal interpretation circuit  16 , or interface, to monitor input signals from, as one example, the temperature sensor  18 . The temperature sensor  18  provides signals that allow for control of the amount of power delivered to the heating element  30 . The controller monitors inputs from a vehicle battery  40  and vehicle ignition  42 . It is understood that a separate ignition input  42  may not be required if all power is obtained from the battery input  40 . In accordance with another alternate embodiment as illustrated in the functional schematic of  FIG. 2 , the controller also monitors a user input and drives a vehicle washer fluid pump  45   a  ( FIG. 8 ) having a pump motor. 
     In one exemplary embodiment, the electronic output circuit  20  controls power coupled to a heater element  30  ( FIG. 1 ) that includes two glow plugs  30   a ,  30   b  ( FIG. 10 ), or other heating element equivalents such as nichrome wire, ceramic heaters, or any metallic or non-metallic type heater mounted in thermal contact with a heat exchanger  80  as shown in  FIGS. 9 and 10 . Fluid is routed past the heat exchanger  80  in thermal contact with these elements by routing fluid into an inlet  32  and forcing the fluid out an outlet  34  having a check valve to prevent fluid leaving the outlet  34  from re-entering a fluid reservoir  103 . The checkvalve could be positioned on the inlet  32 . The inlet receives washer fluid from a fluid reservoir  35  ( FIG. 8 ) of a motor vehicle and the outlet  34  delivers heated washer fluid to nozzles  37  ( FIG. 8 ) mounted to the vehicle which direct the washer fluid against the vehicle surface, typically a windshield, headlamps etc. In the exemplary embodiment the heating elements  30   a ,  30   b  are glow plugs.  FIGS. 9 and 10  depict an exemplary embodiment of a housing  41  that defines a fluid reservoir  103  that surrounds the heat sinks. The housing  41  is constructed from plastic, or other material with favorable thermal characteristics. 
     The programmable controller  14  ( FIG. 1 ) constructed in accordance with the exemplary embodiment of the invention implements control algorithms for washer heater control output functions in response to vehicle input signals. As washer fluid temperature changes due to ambient temperature changes, battery voltage changes, and the like, the duration of applied heat is increased or decreased in order to maintain a washer fluid at or near a target temperature. Control of the heating may also include redundant failsafe mechanisms such as a thermal fuse  524  ( FIG. 9 ). 
     Controller Schematics 
     The block diagram shown in  FIG. 1  and the more detailed schematic of  FIG. 4  depict operation of a control system  10  having external electrical connections, which include Battery  40 , Ground  44 , and Ignition  42 . The system block diagram  111  shown in  FIG. 2  shows further external electrical connections including a user operated Clean Switch  113  and an output  115  to drive a vehicle washer pump motor. The Battery input connection  40  provides the voltage supply needed by the control system  10 . This connection allows the high current flow required by the heating element. The Ground connection  44  provides the current return path to the battery negative terminal. This ground connection allows the high current flow required by the heating element plus the requirement of the control system  10 . An Ignition input  42  provides power to the controller. It is understood that separate ignition input  42  may not be required if all power is obtained from battery input  40 . The battery voltage is monitored by the controller  14  to determine if there is sufficient voltage present to allow the control system to operate. 
     The input  102  from the temperature sensor  18  in physical contact with the heat exchanger  80  is directly related to washer fluid temperature. Washer fluid temperature is monitored by using a temperature sensor such as a thermistor, RTD, or the like. The washer fluid is monitored non-invasively by attaching the temperature sensor to the heater. Alternatively, the fluid temperature could be monitored invasively by placing a temperature sensor directly into the fluid through a threaded fitting or other suitable attachment method. 
     Operation 
     The controller receives a wake-up command signal from the Ignition input  100  ( FIG. 3 ). When the Ignition input is above a predetermined voltage, the controller  14  drives the heater element  30  if the following are true:
         1. The ignition voltage is greater than a first predetermined level and less than a second predetermined level.   2. The sensed Heater element temperature is less than a predetermined level.
 
Cleaning the windshield with warmed fluid can be accomplished by the following:
   a. Application of ignition  42  will cause the unit to heat the volume of fluid. During the heating time an indicator LED  119  flashes. Alternately, the LED could remain off until the fluid has been heated at which time the LED will turn on either 100% or flashing. The LED is shown as part of the clean switch  113 , but a skilled artisan could move the indicator external to the switch.   b. During heating of the fluid if the clean switch  113  is pressed, the LED will begin flashing to confirm the operator&#39;s desire to use smart mode. If heating has already completed and the indicator lamp is illuminated (not flashing), momentarily activating the clean switch  113 , initiates a smart mode consisting of the energization of a washer pump and wiper motor. During heating   c. Output  115  activates the washer pump  117  to dispense fluid on the windshield. In the embodiment shown in  FIG. 4 , an external controller  123  activates a wiper motor  121  in response to a signal from the washer switch  113 . One skilled in the art could have the same controller  14  activate the wiper motor  121  and the washer pump  117 .   d. Hot fluid will be sprayed on the windshield and the windshield wipers will cycle automatically, when the hot fluid reduces to a predetermined temperature or time, output  115  deactivates, thus completing the smart mode and washer spray/wiper cycling will halt. Momentarily pressing clean switch  113  during the smart mode will cancel the operation. The cleaning switch can be configured to heat fluid to a predetermined temperature (or time) and dispense and reheat and dispense fluid multiple times.   2. With ignition  42  applied and when indicator  119  is illuminated (not flashing) indicating warm fluid is available, the activation of the existing vehicle wash switch will dispense fluid for as long as the switch is closed for on-demand cleaning.   3. The activation of the existing vehicle wash switch will dispense fluid for as long as the switch is closed for on-demand cleaning regardless of fluid temperature.       

     An output driver  20  depicted in  FIG. 1  and  FIG. 2  applies power to the heater after starting the heating cycle. The output driver will then begin applying power to the heater to maintain the temperature of the fluid. A fuse  55  is located between the battery connection and the heater element external to the housing  50  in the illustrated embodiment as shown in  FIG. 8 . An alternative embodiment could have the fuse  55  internal to the housing as shown in  FIG. 1 . In the exemplary embodiment of the invention, the desired heater temperature is predetermined to be in a range between 120 and 150 degrees Fahrenheit. Placing the temperature sensor  18  in physical contact with the heating element and maintaining the heater temperature at a temperature at or below 150 degrees Fahrenheit prevents the heating element from heating the cleaning fluid to an undesirable temperature, such as boiling. This helps prevent the formation of mineral deposits that could potentially clog the nozzle  37  ( FIG. 8 ). As depicted in  FIG. 9  if the temperature sensor  18  is not mounted directly on the heating element, but is rather located in the fluid reservoir  103 , only an approximate, latent measurement of the heating element temperature is sensed. This would allow the heat exchanger  80  to heat to a temperature that is hotter than the desired fluid temperature in reservoir  103  and potentially cause the formation of nozzle clogging mineral deposits. The output driver  20  ( FIGS. 1 ,  2 ) will remain active as long as the ignition voltage is above a predetermined voltage and the heater temperature is below the desired heater temperature as determined by the temperature sensor  18 . When the ignition  42  is turned off, the controller is deactivated. 
       FIG. 3  depicts one implementation of the output circuit  20 . A heater connection  60  is shown in the upper right hand portion of the  FIG. 3  depiction. This connection is grounded by means of initiating conduction of two power Field Effect Transistors (FET)  110 ,  112  which provide a current path to ground from the heater connection  60  to the ground connection  44  through a pair of reverse polarity protection FET transistors  114 ,  116 . The two transistors  110 ,  112  are turned on or rendered conductive by means of a pre-drive transistor  120  that is coupled to an output  122  from the microprocessor controller  14   a  ( FIG. 1 ). First consider a high signal from the controller  14   a  at this output  122 . This turns on transistor  120  that pulls an input  124  of a totem pole transistor combination  126  low. This signal turns on a lower of the two transistors of the totem pole combination to send an activation signal that turns off the two FETs  110 ,  112 . 
     When the controller provides a low output from the controller  14   a  at the output  122 , the transistor  120  turns off and pulls an input  124  to a totem pole transistor combination  126  high. This signal turns on an uppermost of the two transistors of the totem pole combination to send an activation signal that turns on the two FETs  110 ,  112 . 
     In the illustrated embodiment, a comparator  140  monitors current through the transistors  114 ,  116  (and by inference the transistors  110 ,  112 ) and deactivates the transistors in the event too high a current is sensed. A five volt signal that is supplied at an input  142  from a power supply ( FIG. 1 ) provides a reference input  144  to the comparator  140 . When the non-reference input exceeds the reference input due to a rise in the current through the transistors  110 ,  112  (and associated rise in the voltage across the transistors  114 ,  116 ) the output  146  of the comparator goes low and removes the input from the gate of the FETs  110 ,  112  that causes them to conduct. This low signal at the output  146  is also coupled to the controller so that the controller can respond to the over current condition. 
     In accordance with the exemplary embodiment of the invention a thermistor temperature sensor  18  is also coupled to the controller. A signal at a junction between the temperature sensor  18  and a resistor coupled to the five volt input  142  generates a signal at an input  150  related to the temperature of the heater element  30  ( FIG. 1 ). 
     Referring to  FIG. 9 , in one embodiment, the control circuit  14  is mounted to a printed circuit board  92  supported by a housing  41 . As seen in  FIG. 3 , a connector  60  is a bent metallic member that attaches to the heating element  30  in the vicinity of the printed circuit board  92  and is in physical contact with the circuit components on the printed circuit board. The connector  60  thereby not only acts as a path to ground for current passing through the heating element  30  but acts as a heat sink that transmits heat away from the printed circuit board. 
     The exemplary control circuit includes a microcontroller as shown in  FIG. 1  running at an internal clock frequency of 4.0 Megahertz. In the exemplary embodiment, the microcontroller  14   a  selectively energizes the heating element  30  based on a voltage applied to the control circuit. This voltage may be the battery voltage  40  and/or the ignition voltage  42 . When the ignition input voltage is applied, the control circuit will power up, come out of reset, and wait for a start delay time imposed by the controller to allow the vehicle&#39;s electrical system to become stable. After this start delay, the control circuit monitors the ignition voltage to determine if the ignition is above a minimum enable voltage. A temperature signal from the sensor  18  is also monitored to see if the temperature of the fluid is below a set point temperature. An output drive feedback signal is also monitored to ensure that the output is in the correct state. If all conditions are such that the output can be enabled, the output  122  ( FIG. 3 ) to the transistor  120  is pulled low. This initiates fluid heating. Initially, the output drive is on 100% for a maximum on time or until the feedback temperature reading approaches a set point temperature. In one embodiment, a preset maximum on time is empirically derived to stay below the boiling point of the cleaning fluid. Subsequently the control will read the heating element  30  temperature and make a determination if power should be reapplied. If the sensed temperature is below the desired setpoint, the output will be re-enabled at a variable duty cycle so that the heating element  30  is heated to the setpoint goal temperature as quickly as possible without exceeding a maximum allowable overshoot temperature. 
     Normal operation consists of maintaining the fluid temperature at the desired setpoint temperature by varying the duty cycle at which voltage is applied across the heating element  30 . The output duty cycle changes based on how far the sensed temperature is below the set point temperature. 
     In the event of excessive current flow through the power drive  20 , the output  12  will automatically be disabled. In this event the signal at the output  146  from the comparator  140  ( FIG. 3 ) will go low. When this occurs the controller  14   a  disables the output to the transistor  120  for a period of time equal to an output retry rate programmed into the controller  14   a . If the fault condition is removed, normal operation of the temperature set point control is re-instituted. An alternate embodiment could have the current sense capability implemented by the comparator  140  omitted. 
     In the event the operating voltage from the battery (and ignition) is too high or too low (≧16.5 and ≦8 volts respectively) the controller  14   a  disables the output  12  for a timeout period. After the timeout period, if voltage conditions are within normal parameters, the controller again enables the output. It is understood that the operating voltage range can be set to whatever voltages are required for a particular application. The exemplary system also incorporates a soft turn-on and turn-off of the heating element. The soft turn-on and turn-off is accomplished by a slow ramp up or down of the output  20  that drives the heating element. The ramping of power reduces the amount of flickering that can be observed from the vehicle headlights. It is recognized that the FET drivers could be run linearly to accomplish the soft turn-on and turn-off of the heating element. It is also recognized that the FET drivers could be run linearly to regulate the temperature of the heating element. It is further recognized that if the FET drivers are run linearly they will produce quantities of heat that will aid in the heating of fluid in the system. 
       FIGS. 5 and 6  illustrate an embodiment of a washer control system  10  that is different from that described previously due to the replacement of control circuit  14  with a thermal fuse device  524  and a bi-metal device  525 .  FIG. 5  is a schematic depiction of such a control circuit. The thermal fuse  524  prevents the washer control system  10  from overheating, while the bi-metal device  525  regulates heating during operation. The bi-metal device could control a relay  612  (see control circuit schematic of  FIG. 6 ) that supplies power to the heating element. In addition, at least one temperature sensor could be used in conjunction with a reference to control a relay that supplies power to the heating element. 
     In  FIG. 7 , the heater  30  is energized with battery voltage by a relay  632  that is activated by ignition of the vehicle. A thermal fuse  637  is in series with the relay coil and is in proximity to the heater  30 . If the heater becomes too hot, the thermal fuse  637  will open and voltage is removed from the heater. The control circuit  14  shown in  FIG. 1  provides a digital signal to a heater energization circuit  630  shown in  FIG. 7 . A digital signal  635  from the controller is converted to an analog voltage by a converter circuit  638 . The converted voltage is provided to a FET  645  as a gate voltage. The gate voltage varies between zero to a FET saturation voltage. The FET  645  is part of a current path for the heater  30  and dissipates an amount of heat that is proportional to the driving voltage that is supplied to it. Since battery voltage is monitored, and the resistance of the heater is known, current flowing through the heater can be calculated by the control circuit  14  to set and regulate the gate voltage. By controlling the relative amounts of power dissipated in the FET and heater, the control circuit can apply varying amounts of current to maintain a desired fluid temperature. By controlling the rate of rise and fall a soft turn an/off can be achieved. 
       FIGS. 9 and 10  illustrate an exemplary fluid heating assembly that provides a heated cleaning fluid to a vehicle surface. A plastic housing  41  defines an interior reservoir  103  and including an inlet port  32  for routing fluid into the reservoir from an external source. The housing further defining an outlet port  34  in fluid communication with the reservoir for dispensing an amount of heated fluid to a nozzle for spraying heated fluid from the reservoir onto a surface such as a windshield. 
     An aluminum heat exchanger  80  has struts  85  of a length to be supported by the plastic housing in a position that is at least partially covered by fluid within the reservoir  103 . First and second transversely spaced generally circular hub segments  82  are coupled together by an intermediate bridging segment. Each hub supports multiple fins  84  that extend outwardly from its associated hub to increase the surface area of the heat exchanger and promote heat transfer to the fluid in the reservoir. The heat exchanger may also be made out of other thermal or reaction with fluids. In the preferred embodiment it is a PTFE penetrated hardcoat anodization. 
     First and second glow plug heater elements include first and second glow plugs  30   a ,  30   b  for heating fluid that passes from the inlet  32  to the outlet port  34  through the reservoir  103  in contact with the heat exchanger  80 . The glow plug heater elements axially extend into the hubs of the heat exchanger so that heat emitting surfaces of the glow plugs (NSN: 2920-01-188-3863) are bonded to interior curved surfaces of the hubs by a thermally conductive material to transmit heat to the heat exchanger. The glow plug heating elements are coupled at one end with generally conductive connector plates  96  for routing energizing signals to the glow plugs. 
     A control circuit supported by a printed circuit board  92  supported by the housing energizes the glow plugs with a voltage and thereby heats fluid passing from the inlet to the outlet through the reservoir. A plastic wall member  94  supported within the housing and has openings for accommodating corresponding first and second glow plugs. A seal  95  contacts the wall member and confines fluid to the reservoir by preventing fluid from leaking outward from the reservoir past the wall member. Air pockets  90  formed in the housing  41  surround the heat exchanger and provide insulation between the heat exchanger an the region outside the housing. These pockets also serve as freeze protection in the event water is frozen in the device. These air chambers allow the reservoir to expand with the freezing water. For optimal protection these chambers may be filled with a compressible material to control the freeze expansion performance. The air pockets  90  may be positioned to cover only a portion of the housing  41 . Connectors route battery, ground and control signals to the control circuit mounted to the printed circuit board. 
     As depicted in  FIGS. 14 and 15  the outlet  34  is defined by an end cap  91  and flexible membrane  97  coupled to the housing  41 . The end cap includes a center throughpassage  99  that allows fluid to flow out the outlet to the nozzles. As fluid is forced through the reservoir, an elastomeric membrane  97  is forced against radially extending slots  98  which open into a central passageway  99 . Once the pressure is removed from the reservoir by deactivating the washer pump the membrane  97  moves from the position shown in  FIG. 14  to cover a narrow throughpassageway  105  to prevent fluid from flowing back into the reservoir from the nozzles. 
       FIGS. 12-13  show the system with a cover component  676  removed. In this embodiment, control system  10  ( FIG. 11 ) receives fluid through an inlet port  681  that then enters into a heatsink  674 . A previously described power FET component is electrically and mechanically attached to printed circuit board (PCB)  675 , using well known methods, and is joined with heatsink  674  by means of a threaded fastener or the like. The heatsink  674  is preferably made from copper, or alloy materials such as aluminum that are similarly effective in thermal transfer. The heatsink  674  is configured to contain a small volume of fluid, preferably situated directly opposite the flat mounting surface of a power FET, ideally for the purpose of cooling power FET during system operation. Conversely, heat transferring from power FET  514  through the heatsink  674  serves to heat the fluid in the reservoir area, adding to the performance of control system  10 . 
     A heatsink  674  also provides electrical connection between the PCB  675  and a first heater coil  671  such as a coil that is depicted in U.S. Pat. No. 6,902,118 which is incorporated herein by reference. Fluid passes from heatsink  674  into first heater coil  671  through aperture  677 , through temperature sensor fitting  678  and into second heater coil  672 . Fluid dispenses into check valve block  680  through an entryway  679  and exits control system  10  by means of outlet port  673 . A check valve block  680  also provides electrical connection between PCB  675  and second heater coil  672 , and is preferably made from copper, or any alloy material capable of withstanding long term exposure to typical fluids used in vehicle washer systems. The assembly as described is preferably attached to base component  682  and enclosed in the cover  676  ( FIG. 11 ), which are preferably molded from plastic material such as 30% glass reinforced polyester, such as that made by GE Plastics under the trade name Valox®. There are many other suitable materials available capable of withstanding the environment and conditions typical of those under a vehicle engine compartment. Power is supplied to this embodiment of control system  10  by means of a connector assembly  683 , while input and output commands are administered by means of a connector assembly  684 . Similar connector assemblies are used in the  FIGS. 9 and 10  embodiment of the control. 
     While the invention has been described with a degree of particularity, it is the intent that the invention includes all modifications and alterations from the disclosed design falling within the spirit or scope of the appended claims.