Abstract:
A windshield wiper is moved across a windshield by a linear motor employing an induction effect. A stator is attached to a vehicle and a driver or truck attached to a wiper blade. Either the stator or driver has coils that are actuated to move the driver across the windshield carrying the blade with it. The blade is swept back and forth with the driver.

Description:
BACKGROUND  
         [0001]    Windshield wipers on cars have traditionally been built around a rotational motor/transmission mechanism that is noisy and incapable of providing full coverage of the windshield.  
         SUMMARY OF THE INVENTION  
         [0002]    A linear motor-based windshield wiper allows a blade to achieve full coverage of a windshield by permitting a wiper blade to be moved across its surface along a line that follows the windshield&#39;s shape rather than a center of rotation as in a traditional motor. In an embodiment, coils are embedded within or behind the windshield. Permanent magnets in a truck with a windshield wiper attached thereto are driven by appropriate actuation of the coils to sweep the blade across the windshield. When the wiper is turned off, the truck is controlled to move to one side where a capture mechanism engages it and locks it to the vehicle, thereby preventing theft. The capture mechanism may be mechanical, magnetic, or any other suitable device to preventing theft.  
           [0003]    In an alternative embodiment, permanent magnets are embedded in the windshield and coils in the truck actuated to move the truck. In this embodiment, the coils in the truck may be powered by a battery recharged by induction, sliding contacts, etc. The truck may be permitted to move by means of wheels, ball bearings, an air bearing (by injection of air through channels in the windshield, for example), magnetic levitation, by sliding contact, or any other suitable mechanism. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is a figurative (non-scale) illustration of a windshield wiper driven by a linear motor according to an embodiment of the invention where the permanent magnets are located in a truck and coils are attached to the windshield.  
         [0005]    [0005]FIG. 2 is a section view of a linear motor truck and stator according to an embodiment in which coils are located inside a windshield.  
         [0006]    [0006]FIG. 3 is a section view of a linear motor truck and stator according to an embodiment in which coils are located within a windshield.  
         [0007]    [0007]FIG. 4 is a figurative (non-scale) illustration of a windshield wiper driven by a linear motor according to an embodiment of the invention where the permanent magnets are located in the windshield and the coils are attached to the truck and the windshield is held at one end only.  
         [0008]    [0008]FIG. 5 is a figurative (non-scale) illustration of a windshield wiper driven by a linear motor according to an embodiment of the invention where the permanent magnets are located in the windshield and the coils are attached to the truck and the windshield is held at two ends by separate trucks.  
         [0009]    [0009]FIG. 6 is an illustration of a control mechanism for operating a windshield wiper driven by a linear motor. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    The following references are hereby incorporated by reference as if fully set forth in their entireties herein: U.S. Pat. Nos. 4,595,870, 5,723,917, 5,519,266. These references describe linear motors and their control mechanisms.  
         [0011]    Referring to FIGS. 1, 2, and  3 , a windshield  90  is wiped by a wiper  50  driven across the windshield by a linear motor consisting of a truck  20  and multiple coils  10 . The coils  10  may be embedded within or behind the windshield  90 . The truck  20  rides on wheels  70 . Alternatively, the truck may be magnetically levitated, driven over an air cushion, or made to slide in contact with the windshield on a low friction surface, such as a fluorocarbon polymer.  
         [0012]    According to well-known principles, magnets  55 ,  56  are arrayed on the truck  20  with alternating polarity. The coils  10  may or may not have ferromagnetic cores  60  as is also known in the field of linear motors. The coils  10  are shown in section at  11  in FIGS. 2 and 3. A controller (discussed with regard to FIG. 6) controls the linear motor such as to drive the wiper  50  at selected speeds across the windshield  90 .  
         [0013]    Note that an alternative configuration to that shown in FIG. 1 is to locate the coils within a non-ferromagnetic portion of a vehicle frame. In this way, the coils will not block light. This “stator” could be located below or above the windshield. If located below the windshield, the truck could be completely hidden by a portion of an engine cover as is used to hide, so-called, hideaway windshield wipers on most cars. Note that yet another alternative is to provide multiple wipers and trucks to allow faster clearing of rain for a given linear motor speed.  
         [0014]    Referring now to FIG. 4, in an alternative embodiment, permanent magnets  125 ,  126  are provided in the stator (either within or on the windshield  90  as shown or in a portion of the vehicle body). The truck  120  carries the coils  100 . The coils  100  may be controlled by a wireless or metallic conductor to convey control signals. The control signals can be from the user interface with a controller on-board the truck or the controller can be in the vehicle with the control signals indicating the current and timing. The coils  100  may have cores or not as indicated with respect to FIGS.  1 - 3 .  
         [0015]    The truck in the embodiment of FIG. 4 may receive power from a battery (not shown) in the truck  120  or power may be conveyed through metallic conductors (not shown) through sliding contacts (not shown) in the manner of an electric train. If a battery is used, the battery may be recharged when the truck  120  is in a resting position adjacent a clamp mechanism  140 . In the latter case, metallic contacts (not shown) may be used to recharge the truck  120  batteries.  
         [0016]    To keep the windshield wiper mechanism from being stolen, the clamp mechanism  140  catches the truck  120  when it is driven to a home position adjacent the clamp mechanism  140 . The clamp mechanism  140  may positively engage and prevent release of the truck  120  until an actuator, under control of the controller (not shown here, but shown and discussed with reference to FIG. 6) permits its release. The clamp mechanism  140  has jaws  155  that may be urged by springs inwardly so that a catch  145  can enter between the jaws  155  passively. When the clamp mechanism  140  is activated, it may be toggled to a lock position by an actuator (not shown; the specifics need not be discussed because many alternatives are a routine matter to design) which prevents the jaws from moving apart until the controller again toggles the clamp mechanism  140  to permit the jaws to be moved apart. In this way, power need not be supplied to the clamp mechanism  140  to secure the truck  120  and wiper  150 .  
         [0017]    Referring now to FIG. 5, a linear motor-driven windshield wiper mechanism has two trucks  220  and  221 , one at either end of the wiper  150 . The controller controls the two trucks synchronously to maintain the wiper  150  in an alignment suitable for clearing the windshield  90 . Note that only one of the trucks  120  is shown with a catch  245  and clamp mechanism  240 , but it is clear that both trucks  120  and  121  may be provided with respective such mechanisms.  
         [0018]    Referring to FIG. 6, a controller  300  controls the one or more trucks  120 ,  121  by way of a winding power control circuit  320 . The latter may be a power circuit that supplies power directly to windings (coils  10 ) embedded in the windshield  90  or it may include only control logic (analog or digital) to provide the proper sequencing for driving the current in the coils  100 ,  200  to move the trucks  120 ,  220 ,  221 . In the latter case, the winding power control circuit  320  would include a signal transmitter according to whatever scheme is employed to signal the truck  120 ,  220 ,  221  coils  100 ,  200 . The controller  300  also controls the latch mechanism  310  to toggle it between its release and capture states. The controller  300  may be a digital controller or an analog controller. The controller receives commands from a user interface  330  which a user employs to turn the system on an off and alter the speed of the wiping action.