A WIPER ASSEMBLY

Abstract: Various embodiments of a wiper assembly are disclosed which facilitate the removal or shattering of ice snow debris lodged and trapped beneath a wiper blade (22) during its movement. Embodiments of the invention are disclosed which provide means to overcome normal urging forces of the wiper arm in a direction toward a light transmitting screen member (12) and to urge the wiper arm of the wiper assembly away from the surface of the screen member (12). Some structures according to the invention may cause the wiper blade (22) to return with an impact force sufficient to shatter ice and snow debris trapped beneath the wiper blade (22) and also possibly frozen to it. Other embodiments include means (120) for imarting vibrational movement to the wiper assembly to release or shatter ice and snow trapped beneath the blade (22) or frozen to it.

Description: - 1 - A Wiper Assembly This invention relates to wiper assemblies. Virtually all vehicles today (cars, trucks, trains, airplanes, boats etc) incorporate one or more windshield wipers which can be deactivated at any time by a driver to sweep repeatedly across an exterior surface of the windshield. A rubber or plastic wiper blade of each wiper assembly engages the exterior surface to clear debris from that portion of the windshield generally in front of the driver to maintain unimpaired visibility. Debris left to build up on the windshield impairs visibility for the driver and if permitted to build up anywhere on the wiper assembly can also reduce wiping efficiency. Maintaining good visibility for the driver lessens the chances of the vehicle becoming involved in an accident and hence increases the safety level for all occupants. The type of debris which can accumulate depends on the geographical location and season. In particular, in parts of the world where winter weather is severe, snow and ice build up on wiper blades is a common experience. In particularly extreme weather conditions, it is not uncommon for snow or ice to freeze to a windshield wiper arm and/or wiper blade. While allowing for movement of the blade across the windshield, such frozen debris may seriously reduce the cleaning action of the blade on the windshield surface. Such freezing may occur while a vehicle is being driven or when stationary. Also, it is common for lumps of ice or snow to become lodged under a wiper blade during use so as to be carried with the blade on its wiping movement. This situation may occur if the blade in moving across the windshield surface is caused to ride onto a mass of ice or snow and move it from a stationary location upon the windshield. As long as an ice or snow mass remains lodged, the efficiency of the wiper blade is severely reduced as a significant portion or all of the wiper blade can no longer engage the exterior surface of the windshield. The thickness of any mass of ice or snow may have a bearing on the wiping efficiency especially if the mass extends along a significant length of the blade. Ice lumps as small as one millimeter if lodged can cause the wiper to experience reduced efficiency. Snow and/or ice formation anywhere on the windshield wiper assembly may contribute to reducing wiping efficiency also by raising sections of the blade off the windshield. A driver of a vehicle when experiencing any of the problems discussed above generally has two options. The first and safest option is to stop the vehicle and, even in extremely cold conditions, exit the vehicle to manually break away the ice or snow frozen to or trapped beneath the wiper blade. This is not always convenient and is certainly not possible for pilots and train operators. Even when driving a road vehicle there are times when stopping to remove debris from a windshield is impossible due to inherent danger. For instance, bridges or certain roadways have little or no shoulder area and when busy with traffic, a driver may not stop safely. Even when there is room to stop by the roadside, it may not be prudent to do so as personal safety may be at risk if the driver leaves the vehicle or if his parked position may present a driving hazard to other vehicles. A common although unrecommended solution for many drivers is to open a window and manually attempt to grasp a windshield wiper as it travels within extended reach of the driver. In reaching the wiper, the driver attempts to lift it momentarily from the windshield in the hope that the debris will become dislodged. Needless to say this is an extremely unsafe practice and, in many cases, such as for larger vehicles, e.g. trains and airplanes, is simply not an option. A further problem concerns the coating of a windshield wiper assembly with ice or snow when the wiper asembly is in the parked position during storm conditions. The thickness of the ice or snow may be such as to trap the wiper assembly in the parked position and thus prevent its operation when the operating motor is energized. It can be an extremely tedious and unpleasant operation for a driver to need to free the wiper manually from the parked position in winter conditions. To ease this problem, some car manufacturers incorporate heating elements in windshield glass. The elements function to heat windshields in a manner similar to that of present day electrical rear window defrosters. This solution is not only expensive and extremely slow in effective operation, it cannot dislodge or melt ice or snow while the wiper assembly is in operation. Furthermore, windshield heating elements are ineffective in releasing wipers from ice or snow when in their parked positions if the wiper blades are not in engagement with the windshields. Other solutions, such as in U.S.Patent No. 5,325,561 issued to Kotlar, teach electrically heating various portions of a wiper blade to melt away snow and ice. Although this solution is somewhat effective when the wipers are in operation, it is an extremely slow operation. This solution can also be very expensive for the owner of the vehicle as wiper blades wear away and should be replaced regularly. Wiper blades of the type taught in the above patent would incorporate an integral electrical heating element thereby drastically increasing the cost of replacement blades. In addition, headlights on some cars incorporate a small wiper arrangement to clean the exterior glass surfaces of the headlights. Headlight wipers may suffer severe ice buildup in winter climates and very often cannot be operated as they become frozen in position. Their proximity to the ground and front end location places them directly in the path of snow, slush and ice raised by passing vehicles or vehicles in front. The invention seeks to provide a combination of wiper assembly and light transmitting screen member which seeks to minimize the above problems. According to the present invention, there is provided a combination of a wiper assembly and a light transmitting screen member, the light transmitting screen member having a surface to be cleaned and the wiper assembly comprising a wiper arm for holding a wiper blade, the wiper arm driveable upon a mounting to carry the wiper blade across the surface to be cleaned with a surface engaging pressure; a first urging means operably connected to the wiper arm for urging the wiper arm towards the surface to be cleaned so as normally to hold the wiper blade against the surface with the surface engaging pressure, driving means for moving the wiper arm in outgoing and return directions of travel across the surface to be cleaned to carry the wiper blade on the surface to be cleaned, and second urging means actuable for urging the wiper arm away from the surface to be cleaned and against the first urging means so as to raise at least a part of the wiper blade completely away from the surface to be cleaned in order to release a frozen mass when this is trapped beneath the wiper blade. In the above combination according to the invention, the light transmitting screen member is considered to include vehicle windshields such as cars, trucks and buses. It is also considered to include a window of an aircraft, ship or train, a protective glass of a headlight and the glass surface found on a side mirror of a truck. Any type of transport may thus benefit from the invention i.e. land, sea or air vehicles. The first urging means is normally in the form of a tension spring which applies the wiper blade to the light transmitting screen member with a - 4 - small force, perhaps to the order of 12 pounds or less and which needs to be overcome by the second urging means. The inventive combination, dependent upon design, is capable of dislodging or shattering ice or snow debris frozen to or trapped between the wiper blade and against the light transmitting screen member. The second means may be electrically powered, e.g. it may comprise basically a solenoid actuator or an electric motor. Alternatively, preferably the second urging means comprises a vibration generator including a driveably moveable mass. This mass is disposed upon the wiper arm and is driveable to provide a directionally changing load laterally to the wiper arm for imparting vibrational movement to the wiper arm to cause at least parts of the wiper blade to move repeatedly into and out of contact with the surface to be cleaned. Such vibrational movement may cause end regions of the blade to be moved repeatedly into and out of contact with the surface to be cleaned. In addition, the vibrational movement may be sufficient to cause regions of the wiper blade spaced from the end regions to move repeatedly into and out of contact with the surface to be cleaned. Alternatively, the second urging means comprises a piston and cylinder arrangement which may be hydraulically or pneumatically powered, and this cylinder arrangement is used in place of the solenoid actuators or electric motors. The second urging means may act directly against the light transmitting screen member itself or cause the wiper blade to move outwardly upon its mounting by applying a force between the arm and the mounting. In one such arrangement, a solenoid actuator may be positioned between the mounting and the wiper arm. Constructions according to the invention dislodge ice or snow debris trapped against the wiper blade as indicated above. Some of these structures may cause the wiper blade to return to the surface of the light transmitting screen member with an impact force sufficient to shatter ice and snow accummulated on and frozenly adhered to the wiper blade or wiper arm. In particular, constructions using the means for imparting vibrational movement are effective for removing and/or shattering ice and/or snow accummulations. The invention also includes a wiper assembly comprising a wiper arm having means for releasably holding a wiper blade, urging means connected to the wiper arm for urging the wiper arm towards the surface to be cleaned in use, and a vibration generator connected to the wiper arm and - 5 - operable for imparting vibrational movement to the wiper arm so as to cause at least parts of the wiper blade to move repeatedly out of and into contact with the surface to be cleaned for effecting release of a frozen mass when this is trapped beneath the wiper blade. Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is an isometric front elevational view of part of a vehicle and incorporating a wiper assembly according to a first embodiment; Figure 2 is a cross-sectional view taken along line 2-2 in Figure 1 of part of the vehicle and showing the wiper assembly in side elevation; Figure 3 is a front elevational view of the windshield of the vehicle in Figure 1 and to a larger scale to show greater detail; Figure 4 is a view similar to Figure 2 and to a larger scale to show the wiper assembly in a first position during use; Figure 5 is a view similar to Figure 4 and showing the wiper assembly in a second position in use; Figure 6 is a view similar to Figure 3 and shows a modification of the first embodiment; Figure 7 is a front elevational view of part of a wiper assembly according to a second embodiment; Figure 8 is a cross-sectional view taken along line 8-8 in Figure 7 and showing the wiper assembly of the second embodiment in one position upon a windshield of a vehicle; Figure 9 is a view similar to Figure 8 showing the wiper assembly of the second embodiment in another position relative to the windshield; Figure 10 is a view similar to Figure 7 of a modification of the second embodiment; Figures 11 and 12 are views similar to Figures 8 and 9 of a third embodiment of the invention; Figure 13 is a cross-sectional view taken along line 13-13 in Figure 12 of the third embodiment; Figures 14, 15 and 16 represent a fourth embodiment and are views respectively similar to Figures 7, 8 and 9; Figure 17 is a view similar to Figure 16 and showing only part of the windshield wiper assembly of a modification of the fourth embodiment; Figure 18 is a wiper assembly according to a fifth embodiment and showing a wiper blade held closely against a windshield; - 6 - Figure 18a is a view in the direction of arrow 18a in Figure 18; Figure 19 is a view similar to Figure 18 and showing the blade moved away from the windshield at both ends; Figure 20 is a view similar to Figure 4, but to larger scale, and shows part of a windshield wiper assembly according to a sixth embodiment; Figure 20a is a cross-sectional view taken along line 20a-20a in Figure 20 and to a larger scale; Figure 20b is a view in the same direction as Figure 20 to showing flexing of a wiper blade in use of the sixth embodiment; Figure 21 is a view similar to Figure 20a of a modification of the sixth embodiment; Figure 22 is a view similar to Figure 20 of a seventh embodiment; and Figure 23 is an isometric view partly in cross-section showing a combination of wiper assembly and windshield according to a seventh embodiment. As shown in Figure 1 , a vehicle has a body 10 with a windshield 12 and has attached thereto a windshield wiper assembly 14 according to a first embodiment. As will be seen from Figure 1 , only one windshield wiper assembly is shown. This is for convenience only and it should be understood that as with other and more conventional vehicles two windshield wipers are actually used, i.e. one for each of the left and right sides of the windshield. As shown by Figure 1 , and more particularly by Figure 3, the wiper assembly 14 is conventional in that it has a wiper arm 16 pivotally attached at one end to a short oscillatable shaft 18 which extends through a part of the body (Figure 2) directly beneath the windshield 12. In known manner the arm 16 may be oscillated from side to side upon the outside surface of the windshield for the express purpose of cleaning the windshield during adverse weather conditions. Also, conventionally, the wiper arm 16 carries, about a mounting pin 20, a wiper blade 22 which is to be held against the windshield with a surface engaging pressure to perform a cleaning operation. To provide the surface engaging pressure, means is provided for urging the wiper arm towards the windshield. The urging means comprises in the embodiment, a tension spring 24 (Figure 4) which extends partly along the length of the arm 16 from the shaft 18. The action is such that any manual effort to raise the arm 16 away from the windshield is resisted by the tension spring 24 which upon the arm being released, immediately forces the - 7 - blade 22 to return into its normal position in engagement with the surface of the windshield. The invention differs from conventional constructions and as illustrated, for instance, by the first embodiment, in that an urging means is also provided to move the arm 16 in a direction away from the windshield and against the influence of the spring 24. This latter urging means is operable to at least lessen the surface engaging pressure of the blade 22 upon the windshield and preferably, as in the embodiment, to move the blade 22 completely away from the windshield for a specific time period. Lessening of the surface engaging pressure is intended to decrease any grip that the blade may have upon any debris in the form of lumps of ice or snow which have become lodged under the wiper blade 22 and are being carried with the blade on its wiping movement across the windshield. Such lumps if remaining in place seriously impede contact of the blade upon the windshield and, as a result, seriously reduce the cleaning action of the blade. Lessening of the surface engaging pressure permits such debris to fall from between the blade and the windshield. Preferably, however, the movement away from the windshield is complete such that debris being carried on its oscillating movement by the blade 22 is released thereby clearing the windshield of the debris. In this embodiment the means for urging the wiper arm away from the windshield comprises an electrically powered means in the form of two magnets 26 and 28 (Figures 3, 4 and 5). The magnet 26 is securely mounted upon the arm 16 at a position towards its pivotted end and out of the line of swept area of the wiper blade 22. However the magnet 26 could also be disposed further along the arm so as to lie within the swept area. The magnet 26 is mounted on the arm 16 so as to be directed towards the windshield 12, as shown particularly in Figure 4, and is held in place in the embodiment by a holding means which may be in the form of a strap 30 extending around the arm 16 so as to hold the magnet 26 against the arm and with the magnet projecting through an orifice in the strap towards the windshield. The other magnet 28 is mounted by epoxy, for example, on the inside surface of the windshield in a position such that during oscillation of the wiper arm 16 across the windshield, the magnet 26 passes directly over the magnet 28. One of the magnets 26 and 28 is an electromagnet, although both may be electromagnets. In the embodiment the magnet 28 is a permanent - 8 - magnet and the magnet 26 is an electromagnet and is energized by wires 32 extending down the arm and forming part of the circuitry of the vehicle, the wires connected to a manually operable switch 34. Upon energization of the magnet 26, a repelling force is generated between the two magnets when the magnets 26, 28 are directly over one another such that the repelling force acts against the wiper arm 16 to move it away from the windshield. The spring 24 offers only light force to move the arm 16 against the windshield i.e. to the order of a few pounds only. The repelling force of the two magnets 26 and 28 may be made sufficient to move the arm 16 so that the wiper blade 22 is forced to lose contact with the windshield. In use, the wiper arm 16 is actuated in conventional manner to perform its oscillating movement so that the blade may clean the windshield in normal fashion. However, when debris, such as a mass of ice or snow, is caught between the blade and the windshield and carried by the blade across the windshield, the oscillating movement of the blade will not release such debris. Hence, as shown by Figure 2, the arm 16 is moving across the windshield in the full outline position with the blade normally in contact with the windshield. Should debris be required to be removed from beneath the wiper blade 22 then the magnet 26 is energized by the driver from within the vehicle. As soon as the magnet 26 passes directly over the magnet 28 a repelling force is generated thereby forcing the arm 16 and blade 22 into the chaindotted position (Figure 2) until the magnet 26 has passed beyond the magnet 28 at which point the arm 16 returns to its full outline positon. As may be seen, and as is more clearly shown in Figures 4 and 5, the movement to the chaindotted position in Figure 2 and as represented in greater detail by Figure 5, provides sufficient gap between the blade 22 and the windshield to enable the debris either to fall away from or be blown away from the blade 22 thereby clearing the windshield of obstruction. For debris which refuses to fall away from, or be blown away from under the blade 22, the wiper blade, while in the raised chaindotted position (Figure 2) will usually travel over and beyond the debris before returning to its normal position. This action generally results in the debris being cleared from the windshield on the next or subsequent pass of the wiper blade as the blade along its complete length is then engaging the windshield. In addition to this, when the blade 22 returns to the windshield, (full outlined position in Figure 2 and as shown in Figure 4), it may return with sufficient force as to shatter accummulations of ice or snow which are frozen on the wiper assembly itself. This shattering action will of course depend upon the hardness and concentration of the ice or snow and upon the impact force. As may be seen, therefore, the magnets 26 and 28 are operable to clear masses or accummulations of ice and snow which are either frozen to the wiper assembly or are carried by the wiper blade across the windshield surface. Movement of the wiper blade away from the windshield has a secondary advantage in that it allows other materials, e.g. leaves or paper, to fall from the windshield. Preferably, an electronic switch means is provided (not shown) to activate the electromagnet 26 which only requires a single momentary action by the user. The electronic switch means would include an electronic holding circuit capable of keeping the electromagnet 26 energized for a sufficient period of time to guarantee the required positioning of the magnets 26, 28 to generate the repelling force, regardless of where in the wiper travel the switch is activated. These advantages also apply to further embodiments and modifications thereof now to be described. In a modification of the first embodiment as shown by Figure 6, a plurality of permament magnets 28 are provided on the inside surface of the windshield. These magnets are positioned in spaced locations around an arc which is to be swept by the electromagnet 26. In use of the modification shown in Figure 6, with the electromagnet 26 energized, the blade 22 is held away from the windshield for an extended period, i.e. over the full length of the sweep of the blade across the windshield. This provides longer periods of time than is possible in the use of the first embodiment, for enabling masses of ice or snow to be removed from beneath the wiper blade, or from frozen adherence to the wiper assembly. In an alternative circuitry arrangement for the modification of Figure 6, one or all of the magnets 28 are also electromagnets. This structure enables the blade 16 to be moved outwards from the windshield at any chosen location during its sweep dependent upon which of the electromagnets 28 is energized for this purpose. In further embodiments now to be described, features of similar construction to those described in the first embodiment will be referred to by use of the same reference numbers as in the first embodiment without further discussion. In a second embodiment as shown in Figures 7, 8 and 9, the means for urging the wiper arm and thus the blade away from the windshield 12 is again an electrically powered means and comprises a solenoid actuator - 10 - 40 having an axially moveable plunger core 42 within a cylindrical housing 44. Means are provided for mounting the solenoid actuator upon the wiper arm 16 with the plunger core 42 having an operative end 46 extending from the solenoid housing 44 and towards the windshield 12. The means for securing the solenoid actuator to the arm comprises a protective rubber or plastic molded surround 48 which is shaped intimately around the cylinder 44 and extends inwardly of the cylinder adjacent the end 46 of the solenoid to surround the plunger core 42 of the solenoid while allowing for its sliding axial movement. The surround 48 has a mounting portion 52 by which it is mounted to the wiper arm 16 as shown in Figures 7 to 9. This mounting portion (which extends in a direction normal to the axis of the solenoid actuator) may be cylindrical in molded form so as to be received upon the arm 16 by its sliding reception down the arm. Alternatively (not shown) the mounting portion 52 may be split along its length to be wrapped around the arm 16. In either case, the surround 48 is secured in position by a holding means comprising two metal clamps 54 surrounding two end portions of the mounting portion 52 and tightened to grip the mounting portion upon the arm 16. Alternatively, other holding means may be provided such as resilient clips which are sprung resiliently into position around the mounting portion 52. As a result, and as shown particularly by Figure 7 when the solenoid actuator 40 is in position it is disposed towards one side of the wiper arm 16. In use of the second embodiment, the wiper arm 16 is moved in oscillatory fashion across the windshield as in the first embodiment while occupying a position relative to the windshield as shown in full outline in Figure 2 and by Figure 8, i.e. with the wiper arm in contact with the windshield with a surface engaging pressure. Should it be required to remove a mass of ice or snow from beneath the wiper blade it is merely necessary to actuate the solenoid actuator which is connected to the circuitry of the vehicle by conductors 32 as in the first embodiment. Solenoid actuation by driver operation of the switch, results in the movement of the plunger core 42 outwardly and into contact with the windshield. As a result of this, the action of the spring 24 to hold the wiper arm in the position of Figure 8 is overcome and the wiper arm is caused to move outwardly to the position of Figure 9. This moves the wiper arm in a direction away from the windshield and positions the assembly somewhat as shown in the dotted position for the assembly in Figure 2. Upon the debris being released from beneath the wiper arm the solenoid actuator is de-energized by the driver to cause the - 11 - wiper arm to return to its Figure 8 position. Dependent upon the solenoid characteristics and its power relationship to the spring 24, it is possible that the wiper arm may return to the windshield at sufficient speed to create an impact load to break any ice or snow accummulation frozen to the wiper arm or wiper blade. The usefulness of the wiper assembly in this respect and in other embodiments, depends not only on the return speed and impact force of the wiper assembly as mentioned above but also on the accummulation, hardness and other characteristics of the snow or ice upon the wiper assembly. Depending on the speed with which the plunger core 42 moves outwardly and into contact with the windshield, a cushioning tip (not shown) placed over the operative end 46 may be required to prevent damage to the windshield. In a modification of the second embodiment as shown by Figure 10, a solenoid actuator 40 is mounted in a different manner upon the wiper arm. In this modified construction the wiper arm 16a is of slightly different construction from the arm 16 of previous embodiments in that it has a local widened area 56 provided with a central aperture 58 for receiving the solenoid actuator 40 through the aperture. The end 46 of the plunger core is directed towards the windshield as described in the second embodiment. The solenoid actuator is mounted within a molded plastic or rubber surround 60 which has integrally formed therewith a metal or hard plastic bracket 62 at one end. This bracket 62 is attached to the wiper arm 16a by rivets 64 although other holding means such as screws or nut and bolt assemblies may be used. In a third embodiment as shown in Figures 11 , 12 and 13, in a wiper assembly, a means 70 for urging the wiper arm away from the windshield comprises a solenoid actuator 72 mounted within a protective surround 74, the surround being mounted upon the wiper arm 16 in a manner similar to that of the second embodiment and also receiving the solenoid actuator in like manner. The solenoid actuator 72 has a projecting plunger core end 76 which faces towards the windshield 12. Positioned upon the windshield 12 is a rigid ramp 78 which is localized in position and disposed along the arc of movement of the plunger core end 76. In normal operation (Figure 11 and full outline in Figure 13) the plunger core end 76 is in a retracted position so that as the wiper arm oscillates over the windshield, the end 76 is spaced from the ramp 78 as it passes over it. However, should it be required to remove a mass of ice or snow moving with and positioned - 12 - beneath the wiper blade, then the solenoid is actuated by driver operation of the switch to force the end 76 outwards towards the windshield (chaindotted position 76a in Figure 13). Upon the end 76 reaching the ramp, and as shown in the chaindotted position 76b in Figure 13, the end 76 is caused to ride over the ramp thereby forcing the wiper arm into a position away from the windshield, e.g. as shown in Figure 12 i.e. in the chaindotted position in Figure 2, thereby enabling masses of ice or snow caught between the wiper arm and the windshield to be released. To cause the outward movement of the wiper arm, either the ramp 78, the plunger core 76 or each of them as shown in Figure 13 has two inclined side surface regions to enable the plunger core end 76 to ride over the ramp while being directed outwardly. It is considered that each inclined surface may lie at a preferred angle of between 15 and 45 degrees to the plane of the windshield at the ramp position to achieve the desired result. In a fourth embodiment as shown by Figures 14, 15 and 16, a means 80 for urging the wiper arm away from the windshield 12 comprises an electrically powered means having a DC motor 82 held in position between the wiper arm and the windshield by a U-shaped holding bracket 84 which extends around the housing of the motor and has two ends 86 which are attached to the underside of the wiper arm by srewthreaded means 88 or rivets as required. The motor 82 is disposed with its axis of rotation extending generally in the direction of oscillating movement of the wiper arm. The means 80 also includes an edge cam 90 which is secured to one end of the rotatable mass of the motor 82 and outwardly from the motor so as to be exposed. As will be seen from Figure 15, the cam edge surface of the cam 90 is shaped so that with the arm 16 moving along its normal path, the cam is clear of the windshield 12. However, should it be required to remove ice or snow from beneath and moving with the wiper arm, then the motor 82 is energized by driver operation of the switch thereby rotating the cam 90 in the direction of the arrows in Figures 15 and 16. The edge profile of the cam is such that the cam rotates into engagement with the windshield 12 and has sufficient lift as illustrated by Figure 16 to raise the arm 16 away from the windshield, e.g. as shown in chaindotted outline in Figure 2, with the wiper blade removed from the windshield. As in previous embodiments, this action results in ice or snow trapped by the wiper arm being permitted to fall or be blown away out of contact with the arm. It will be noticed that a lift portion 92 of the cam 90 ends abruptly at an inwardly extending edge face 94. Upon - 13 - the cam moving past the position where the lift surface engages the windshield, the wiper arm is caused to return towards the windshield with an impact force under the influence of the spring 24. This may have the effect of shattering ice or snow which has settled and has frozen to the wiper assembly, and comments regarding the usefulness of this action for snow or ice removal are similar to those contained in the second embodiment. It is interesting to note in the fourth embodiment that the motor 82 may be energized over any desired period of time. Thus the cam 90 will continue rotation during this time period and causes repeated cycles of movement of the arm away from the windshield. This action may be particularly useful for ice or snow removal and will take place progressively along the sweep of the arm over the windshield. In modifications of the fourth embodiment, a cam may have a different edge profile to provide a different result. For instance as shown in the modification by Figure 17, a symmetrically arranged elliptical form of cam surface is provided upon a cam 98. This shape of cam will of course result in movement of the wiper arm 16 away from the windshield twice for each motor revolution. The effectiveness of the impact force upon the windshield for ice and snow removal in the fourth embodiment and the modification thereof, depends upon the shape of the cam surface and also may depend upon the rotational speed of the motor. In a fifth embodiment as shown in Figures 18, 18a and 19, a wiper assembly has means 100 for urging an end portion of a wiper blade away from the windshield 12. The means 100 actually operates to move either end portion or both end portions of the wiper blade away from the windshield as desired dependent upon the position of location of debris under the wiper blade. The means 100 comprises two solenoid actuators 102 secured to a wiper blade carrier 104 for the wiper blade 22, one solenoid actuator on each side of the mounting pin 20 of the wiper blade carrier to the wiper arm 16. The solenoid actuators face in opposite directions along the wiper arm carrier 104, (see Figure 18a particularly) with each solenoid actuator having a plunger core with an end 108 projecting from the cylindrical housing 110 of the actuator 102 towards the closer free end of the wiper blade carrier. Each of the plunger core ends 108 is connected by a rigid link 112 to the closer free end region of the wiper blade carrier 104, the link 112 having a pivotal - 14 - connection at each end. Upon energization of each of the actuators 102, the associated plunger core moves in a direction away from the closer free end of the wiper arm carrier thereby drawing the end 108 and the link 112 in the same direction. This effects a shortening of the distance between the pivotal position of the link 112 to the carrier 104 and the housing 110 of the solenoid actuator. As a result of this, the carrier arm and thus the wiper blade at that end of the wiper blade are caused to move outwards from the windshield thereby providing a clearance between the blade and the windshield such as is shown at either end of the structure in Figure 19. At this stage, only the central region of the wiper blade actually touches the windshield. The clearance between each end portion of the wiper arm and the windshield enables loosening of ice or snow debris carried beneath the wiper blade at the end portion. A subsequent shattering effect may occur when the solenoid actuators de-energize and the ends of the wiper blade return against the windshield with impact. In each of a sixth and seventh embodiments to be described, a wiper arm and thus a wiper blade are subjected to vibration which produces a recurrent impact on the windshield with sufficient force to dislodge or shatter ice or snow when this is trapped between the blade and the windshield or is frozen to the wiper arm or blade. In these particular embodiments, as will be seen, a moveable mass is driven for the purpose of creating this vibration. Thus, the driven speed and size of the moveable mass, together with its manner of application and distance from the pivotal axis of the wiper arm are all instrumental in deciding the frequency of vibration of the wiper arm and wiper blade. This frequency may also be partly governed by the natural frequency of oscillation and stiffness of the wiper arm and wiper blade assembly and is also largely influenced by the size and design of the assembly and the force of the tension spring which normally urges the wiper blade against the windshield. Further, ambient temperature conditions may play a role as they have an influence upon the stiffness of the wiper blade material and also upon the tension spring. It follows that many parameters are involved in producing the desired force to dislodge or shatter ice and snow trapped and carried by the wiper blade or frozen to the wiper assembly. Hence, the size of the mass which is needed to produce the desired result is dependent upon the above parameters for any particular wiper assembly structure. Indeed, the speed of movement of the driven moveable mass and the size of the mass may be such that the - 15 - resultant frequency and amplitude of vibration of the wiper blade are entirely erratic. Hence, the resultant frequency and amplitude may differ from one vibration to another dependent upon whether the moving mass is working in sympathy with, or is acting against, the direction of vibration caused in the wiper blade at any instant. It is clear from studies which have been conducted that the vibrational force produced should not only provide visible vibration to the naked eye of the wiper blade assembly, but also should cause at least parts of the wiper blade to move repeatedly into and out of contact with the surface of the windshield when no ice or snow is present. The vibrational force operating in conjunction with springs mounting the wiper blade to the wiper arm may, for instance, at specific moments in time, cause the end regions of the wiper blade to move out of contact with the windshield surface in repeated fashion. At other specific moments, lengths of the wiper blade between the end regions may move away from the windshield surface with lengths of the wiper blade towards or at the end regions at that time in contact with the windshield surface. The vibrational force produced and which causes the blade to move into and out of contact with the windshield as just discussed, results in movement of the blade into and out of contact with ice or snow when this is trapped by, or is moving with, the wiper blade, either to release the mass of ice or snow as a single entity or to give repeated blows to shatter the mass, thus resulting in its dispersion. While the term "amplitude" is used in this discussion, the term is used rather loosely in that it is normally used to refer to the extent of swing of a vibrating body on each side of a mean position. However, in constructions in the sixth and seventh embodiments, there is no mean position as the wiper blade is forced by the tension spring on the arm against the windshield thereby deadening or damping out "amplitude" in its normal sense. The term "amplitude" is thus used in this specification to refer to the extent of lateral movement of the wiper arm and blade assembly over the dampening effect of the tension spring. From the above, it follows that with regard to the employment of vibrational movement under the instrumentation of a driven moveable mass, the invention as exemplified in the sixth and seventh embodiments is concerned with the generation of vibrational characteristics which is in combination with the momentum of the moving mass to produce sufficient vibrational force to release and/or shatter a mass of ice or snow beneath the - 16 - wiper blade or shatter a mass frozen to the blade or to the wiper arm. It is in this realization that the inventive concept lies with these embodiments. In a sixth embodiment as shown in Figure 20, a means 120 is provided for imparting a vibrational movement to the wiper arm and thus to the wiper blade during a sweeping action of the wiper arm or in a stationary position. The means 120 comprises a DC electric motor 122 which is positioned on the side of the wiper arm remote from the blade and close to the pivot position of the wiper blade. The driven shaft 124 of the motor carries a mass 126 which is eccentrically carried in relation to the rotational axis of the motor. The motor 122 is rigidly held within a surrounding environmentally protective casing 129 of rubber or plastic and which also surrounds the mass while providing clearance to allow for eccentric rotation of the mass. Surrounding the casing and the arm 16 is a strong metal strap 127 to secure the casing and the means 120 in position. The mass 126 is offset in such a way as to cause the wiper arm 16 to vibrate in a direction towards and away from the windshield, as shown by the arrows 128, when the motor 122 is energized by the driver by operation of switch 34 within the vehicle. As vibrational movement occurs during oscillation of the wiper arm, any mass of ice or snow trapped beneath and moving with the wiper blade is either ejected to cause its dispersion or any ice or snow frozen to the wiper assembly is shattered. The momentum of the eccentrically rotating mass in combination with the vibrational characteristics of the wiper arm and blade assembly produces a vigorous vibrational force which deflects and deforms the wiper blade sufficient to raise parts of the blade repeatedly out of contact with the windshield. The repeated movement into and out of contact with the windshield permits and encourages the dislodgement of ice or snow when trapped beneath the wiper blade and this is assisted by the repeated hammer-like blows of the blade upon the ice or snow as the parts of the blade return towards the windshield surface. It is found that such masses of ice or snow are dispersed within a few seconds, e.g. 1 to 10 seconds. Further, the vibrational force provides a sufficiently vigorous vibration of the wiper assembly as to shatter ice and snow frozen to the assembly. Such shattering is also assisted by a flexing of the wiper blade during its vibrational movement. The blade may flex so that in some flexed positions, end parts of the blade move out of contact with the windshield while other parts remain in contact therewith. In other flexed positions, the end parts remain in contact with the windshield while other - 17 - parts are flexed outwards away from it. This is illustrated diagrammatically in Figure 20b wherein the windshield engaging edge of the wiper blade 22 is shown in one flexed position 23a with end parts raised away from the windshield as shown by arrows at the blade ends and in another flexed position 23b with more central parts away from the windshield (arrows in blade center). In the latter position the end parts are in contact with the windshield. In Figure 20b, other parts of the wiper assembly are omitted for clarity. The rotational speed of the motor together with the size and eccentric positioning of the mass from the pivotal axis of the wiper arm all contribute to the effect of the vibrational motion. The vibrational characteristics are determined by the design and size of the wiper arm and blade assembly and the natural vibrational frequency thereof together with the strength of the tension spring and the force with which the tension spring urges the wiper blade against the windshield. Hence, these characteristics differ from one design to another. In this embodiment it has been discovered that the means 120 of the embodiment is particularly effective. In the embodiment, the electric motor is one made by Sanco Electrical Company and is a 12 volt DC motor having the code number M8M12M24 and operable, in this embodiment, up to or around 13,500 rpm. The driven shaft of the motor is secured by solder to the mass 126 which is approximately 45 grams, made from lead and is circular with a diameter of 1.1/4 inches (see Figure 20a). The axis of the motor lies 3/16 of an inch from an edge of the mass. The wiper blade has a length of 16.5 inches and the mounting axis of the blade is 14.75 inches along the wiper arm from the pivotal axis of the arm, i.e. at shaft 18. The mass 126 operates effectively at a distance of 3.5 inches approximately along the wiper arm towards the shaft 18, i.e. away from the mounting axis of the blade to the wiper arm. For guidance.with the mass effective at this position, a force of between 2 and 3 pounds is necessary, with the wiper assembly inoperative so as to raise the wiper blade 0.5 inches approximately away from the windshield surface. However, such a distance is not required in performance of the invention as lesser distances of movement away from the windshield will achieve the desired objective, e.g. about .0625 inches or slightly greater . If distances progressively closer to the shaft 18 are chosen for positioning the means 120, vibration of the assembly becomes less pronounced and progressively larger masses may become necessary to achieve the inventive effect. In the embodiment, the - 18 - rotational axis of the motor and mass is parallel to the longitudinal axis of the wiper arm as shown. However, the motor and mass may be oriented at a different angle to the longitudinal axis and produce a similar effect. It has also been found that an eccentric mass of 30 grams has had a similar effect, but has required slightly longer to remove ice and snow trapped beneath the wiper blade. It is also found that masses lesser than 30 grams showed a decreasing ice or snow removal effect. With this particular structure and with a mass below 15 grams in the means 120, it is found that there is no effect upon removal of ice or snow either trapped beneath the wiper blade or frozen to it. It is possible that this smaller mass may achieve the desired effect upon smaller wiper systems, e.g. headlight wiper systems. In the construction of the embodiment with the small mass, the wiper blade does not move away from the windshield at any position along its length when no ice or snow is trapped beneath the blade. In a modification of the sixth embodiment, a mass 130, as shown in Figure 21 has been used instead of the mass 126. The mass 130 has a weight of 45 grams and has a substantially crescent shaped main portion 132 mounted by an integral radial arm 133 to the driven shaft 124 of the motor 122. The part of the structure with most of the mass, i.e. the main portion 132, located to one side of the axis of rotation about shaft 124 places the center of gravity of the mass at a substantially greater distance from the axis than is found with the mass 126. This positioning of the center of gravity effectively increases the vibrational force beyond that possible with mass 126 although both masses are of substantially equal weights. The mass 130 has a smaller radius, thus allowing for smaller commercial packaging. In the sixth embodiment and in the modification thereof, the vibrational force is sufficiently vigorous to flex parts of the wiper blade into and out of contact with the windshield when no ice or snow is present. This effectively produces the desired result when masses of ice or snow are trapped beneath and move with the wiper blade as the wiper blade moves into and out of contact with the trapped mass or vigorously vibrates against it. This results in the release of the mass or in shattering of the mass which again releases it. Shattering of ice or snow frozen to the wiper assembly also results. In contrast, as referred to above, it has been found in tests that when lesser masses have been employed in vibration generating means to provide less vibrational force, i.e. no part of the wiper blade has been raised from the windshield, then over an unacceptable time period of several - 19 - minutes, masses of ice or snow, when trapped, have not been released from beneath the wiper blade or shattered. In addition, in the sixth embodiment, vibrational movement may be effective in removing and/or shattering ice and/or snow accumulated upon and around the wiper assembly when this is in the parked, i.e. non-use position, alongside or below a bottom edge of the windshield. The vibrational force creates cracks in the ice and snow thereby loosening its hold upon the wiper arm and blade and permitting oscillating movement of the wiper assembly across the windshield. In a seventh embodiment as shown in Figure 22, a windshield wiper assembly 138 which is otherwise similar to the sixth embodiment has instead of a vibration generating means with an eccentrically driven mass, a vibration generating means 139 having a reciprocally driven mass. In the seventh embodiment this vibration generating means comprises a solenoid actuator 140 mounted upon the wiper arm with the axis of the solenoid actuator extending substantially normal to the longitudinal direction of the arm 16. The solenoid actuator is mounted within a protective molded surround 142 which has an inside space 143 to allow for axial movement of the plunger core 144 of the solenoid actuator within the surround. The surround 142 is secured to the arm 16 by two spaced metal straps 145. The plunger core is springloaded in one direction and actuation of the actuator causes movement of the core into the space 143. The core has a mass such that upon being actuated intermittently at short spaced intervals, the wiper assembly 138 is caused to vibrate towards and away from the windshield. The mass, which may need to include a head weight 146 at one end of the core, is sufficient for its momentum in conjunction with the vibrational characteristics of the wiper arm and blade to produce a sufficiently vigorous vibration of the assembly 138 as to raise parts of the wiper blade from the surface of the windshield as in the sixth embodiment, i.e. when ice or snow is not trapped beneath the blade. The total mass of core and head weight may be less than is required in the sixth embodiment, because all of the mass is acting at any particular moment in one direction and is not at least partly counterbalanced by part of the mass acting in the opposite direction as with a rotational mass. This satisfactorily results in removal and/or shattering of masses of ice or snow when trapped beneath the wiper blade and in shattering ice or snow frozen to the wiper assembly. The vibration generating means also includes a driver operated on/off electronic or - 20 - electrical switch 148 as shown diagrammatically in Figure 22, the switch operating a pulsing circuit. This switch, actuates the solenoid actuator in pulsing fashion by the elctronic pulsing circuit to produce a required reciprocating movement of the plunger core which causes the desired vibration of the wiper arm assembly. In an eighth embodiment as shown in Figure 23, as in previous embodiments the wiper arm 16 is carried upon the shaft 18 for oscillating movement. In this embodiment the means for moving the wiper arm and thus the blade away from the windshield comprises a solenoid actuator 150 which is operably mounted to apply a force between the shaft 18 and the arm 16. Thus one end of the actuator is attached either to the shaft 18 or a sleeve (not shown) surrounding it and the other end is attached to the arm. In this particular embodiment, the cylindrical housing 152 of the actuator is pivotally mounted in trunnions 154 to the shaft 18 and at the other end, the plunger core 156 is pivotally connected by a pivotal cross-shaft 158 mounted in sides 160 of the wiper arm 16. In this structure the means for urging the wiper arm towards the windshield is provided by a return compression spring 162 within the housing 152. Thus, with the actuator de-energized the spring is in an expanded condition to hold the wiper arm towards the windshield for normal wiping operation and as shown in full outline in Figure 23. To release and/or shatter ice or snow debris from beneath the wiper blade, the solenoid is energized against the spring so that the plunger core moves upwards and forces the wiper arm 16 to pivot outwardly and away from the windshield to space the wiper blade therefrom. This latter position is shown in chaindotted in Figure 23 and corresponds to the chaindotted position in Figure 2. For those embodiments which can raise the wiper arm away from the windshield at any point during wiper arm travel (e.g. embodiments 2, 4 and 8) it may be advantageous to provide a switch disabling means capable of disabling the lifting action while the wiper assembly is parked. This may be especially advantageous on those vehicles which effectively hide the wiper assembly in the parked position, e.g. under a cowl assembly. The switch disabling means may comprise, for example, a mercury switch arrangement disposed on the wiper arm and electrically connected to disable the actuators, e.g. in embodiments 2, 4 and 8 from being energized in the parked position. The switch disabling means may also comprise a switch which is enabled or disabled dependent on the rotational position of the drivable mounting. - 21 - It is envisaged that the invention in any of its various embodiments may be sold in kit form. The kit would comprise replacement arms with or without wiper blades and would include, for example, the solenoid actuators, and vibrational means together with any hardware required for mounting to a vehicle.

Claims: - 22 - WHAT IS CLAIMED IS: 1. A combination of a wiper assembly and a light transmitting screen member comprising: a light transmitting screen member having a surface to be cleaned; a wiper assembly comprising a wiper arm for holding a wiper blade, the wiper arm driveable upon a mounting to carry the wiper blade across the surface to be cleaned; first urging means operably connected to the wiper arm for urging the wiper arm towards the surface to be cleaned so as normally to hold the wiper blade against the surface with a surface engaging pressure; driving means for moving the wiper arm in outgoing and return directions of travel across the surface to be cleaned to carry the wiper blade on the surface to be cleaned; and second urging means actuable for urging the wiper arm away from the surface to be cleaned and against the action of the first urging means so as to raise at least a part of the wiper blade completely away from the surface to be cleaned in order to release a frozen mass when this is trapped beneath the wiper blade. 2. A combination according to claim 1 wherein the second urging means comprises a vibration generator including a moveable mass disposed upon the wiper arm and driveable to provide a directionally changing load to the wiper arm for imparting vibrational movement to the wiper arm to cause at least parts of the wiper blade to move repeatedly out of and into contact with the surface to be cleaned. 3. A combination according to claim 2 wherein the vibrational movement produced causes end regions of the blade to be repeatedly moved out to and into contact with the surface to be cleaned. 4. A combination according to claim 3 wherein the vibrational movement produce is sufficient to cause regions of the wiper blade spaced from the end regions to move repeatedly out of and into contact with the surface to be cleaned. - 23 - 5. A combination according to claim 2 wherein the vibration generator also comprises an electric motor having a rotatable shaft and the driveably moveable mass is eccentrically and driveably mounted upon the rotatable shaft. 6. A combination according to claim 5 wherein the driveably moveable mass comprises an arcuately shaped portion radially spaced from the rotational axis of the ratable shaft, and a radially inwardly extending arm driveably connecting the arcuately shaped portion to the rotatable shaft. 7. A combination according to claim 2 wherein the vibration generator also comprises a solenoid actuator and the driveably moveable mass comprises a plunger core of the solenoid actuator, and switch means is provided which, upon actuation, automatically operates repeatedly for actuating the solenoid actuator in intermittent manner to cause repeated reciprocation of the plunger core to produce the vibrational movement to the wiper assembly. 8. A combination according to claim 1 wherein the second urging means comprises a vibration generator connected to the wiper arm and operable for imparting vibrational movement to the wiper arm so as to cause at least parts of the wiper arm to move repeatedly out of and into contact with the surface to be cleaned for effecting release of a frozen mass when this is trapped beneath the wiper blade. 9. A combination according to claim 1 wherein the first urging means comprises spring means operatively connected to the wiper arm to provide the surface engaging pressure, and the second urging means comprises an electrically powered means operable to act against the spring means. 10 A combination according to claim 9 wherein the electrically powered means comprises a solenoid actuator with an axially moveable plunger core, the actuator mounted upon the wiper arm and operable to move the plunger core so as to act against the surface to be cleaned and urge the wiper arm away from that surface, the spring means operating to move the wiper arm towards the surface upon deactivation of the solenoid actuator. - 24 - 11. A combination according to claim 9 wherein the light transmitting member is a windshield and the surface to be cleaned is an exterior surface of the windshield. 12. A combination according to claim 9 wherein the electrically powered means comprises two magnets one at least of which is an electromagnet, the magnets being secured one to the wiper arm and the other to the light transmitting screen member positioned on the surface opposite to the surface to be cleaned, energization of the electromagnet resulting in a repelling magnetic force between the two magnets when the magnets are in close positional relationship and as the magnet secured to the wiper arm pases the other magnet when the wiper arm moves over the surface to be cleaned, the repelling force urging the wiper away from the surface to be cleaned, and upon the magnets relatively moving outside the close positional relationship, the repelling force decreases to enable the spring means to operate and return the wiper arm towards the surface to be cleaned. 13. A combination according to claim 12 wherein the electromagnet is secured to the wiper arm. 14. A combination according to claim 13 wherein a plurality of magnets are mounted upon the opposite surface of the light transmitting screen member in sequentially spaced apart positions whereby, as the wiper arm moves over the surface to be cleaned, a repelling magnetic force is created between the electromagnet when energized and the plurality of magnets sequentially along them. 15. A combination according to claim 12 wherein a plurality of electromagnets are mounted upon the opposite surface of the light transmitting screen member in sequentially spaced apart positions whereby, as the wiper arm moves over the surface to be cleaned and with any one of the plurality of electromagnets energized, a repelling force is created between the energized electromagnet and the magnet on the wiper arm when in the close positional relationship. - 25 - 16. A combination according to claim 9 wherein the electrically powered means comprises an electrical motor driveably carrying an edge cam which is spaced from the surface to be cleaned when the electric motor is de-energized, energization of the electric motor effecting upon each revolution of the cam, contact by a lift portion of the cam edge surface with the surface to be cleaned so as to urge the wiper arm away from that surface and, as the lift portion moves away from the surface to be cleaned, the spring operates to return the wiper arm towards that surface. 17. A combination according to claim 16 wherein the lift portion of the cam ceases contact with the surface to be cleaned sufficiently abruptly to enable the spring means to return the wiper arm towards that surface with an impact force. 18. A combination according to claim 1 wherein the second urging means is operable to apply a force between the mounting and the wiper arm to cause the wiper arm to pivot upon the mounting and urge it away from the surface to be cleaned. 19. A combination according to claim 18 wherein the urging means comprises a solenoid actuator pivotally connected at its two ends to the mounting and to the wiper arm. 20. A combination according to claim 19 wherein the solenoid actuator is energizable to force the wiper arm away from the surface to be cleaned and comprises a return spring which provides the first urging means and upon de-energization of the actuator, returns the wiper arms towards the surface to be cleaned. 21. A wiper assembly comprising a wiper arm having means for releasably holding a wiper blade, urging means connected to the wiper arm for urging the wiper arm towards the surface to be cleaned in use, and a vibration generator connected to the wiper arm and operable for imparting vibrational movement to the wiper arm so as to cause at least parts of the wiper blade to move repeatedly out of and into contact with the surface to be cleaned for effecting release of a frozen mass when this is trapped beneath the wiper blade.

Inventors: KELLY MICHAEL J, KELLY, MICHAEL, J.
Applicants: KELLY MICHAEL J, KELLY, MICHAEL, J.
Application year: 1998
Main classification: B60S1
IPC codes: B60S1