Patent Publication Number: US-3879592-A

Title: Switch having pivoted u-shaped resilient conductive blade

Description:
States Patent Comertnrd et al.  
 [ SWllTCli-ll HAVING PIVOTED Li-SHAPED Primary E.\&#39;aminer-Robert K. Schaefer RESILKENT CONDUCTHVE BLADE Assistant Eraminer-William J. Smith [75] Inventors: John Comertord Chicago; Richard Attorney, Agent, or F1rmM1chael, Best &amp; Friedrich L. Lauritsen, Hoffman Estates, both of I11. [57] ABSTRACT [73] Assignee: Controls Company of Am i The switch has a pair of blades each of which is a s m park 1 piece of flat stock formed into a generally U shape with the shorter leg pivoted on the notched center terl22] Flled: 1974 minal and normally contacting the N.C. terminal while [21] Appl. No; 441,439 the longer leg overlies the NO. terminal. When the actuator (as distinct from the handle) is moved towards the N.C. terminal, the free end engages the ter- 200/153 G; 200/2411 2O0/339 mina] with considerable contact pressure while the ac- [51 llllllt. Cl. lllOlh 23/24 tumor engages the upstanding tab forcing the blade to [58] Flew Search ZOO/I53 159 the left to wipe the blade on the terminal. The center- 200/..41, 153 LB, 246, 283, 67 G, 6 B 6 C i spring returns the actuator to normal. When the actuator is moved towards the N.C. terminal, the slop- [56] References C&#39;ted ing tab is engaged and the blade wipes the N.C. termi- UNlTED STATES PATENTS nal. In the foregoing the distinction between the actu- 2.457.153 12/1948 Hubbell 200/153 LB r an he han le should be kept in mind the 3,299,241 [/1967 Sayward 200/246 handle moves opposite to the actuator. This switch 3.527.913 9/1970 Gionct 200/6 BB X can handle large DC current without using precious 3.561463 2H97l Long 200/6 C X metals. thus achieving greatly improved performance 3.588.402 6/l97l Heath 200/67 G at low COSL 3.749.872 7/1973 Foster 200/159 A X 8 Claims, 5 Drawing Figures 1&#39; t/1&#39; ml 1&#39; Hill [11 t 1. l l 36 I t i m I 1 mm =00.  
 ll W 411&#39;- i/ lml PATENTEBAPRZZIQYS SHKET 1 Eli 2 SWITCH HAVING PIVOTED U-SI-IAPED RESILIENT CONDUCTIVE BLADE BACKGROUND OF THE INVENTION Prior Art This switch is designed to meet the requirements for the window lift switch as used in theautomotive industry. The usual switch in this environment employed a leaf spring blade provided with a silver contact, it being usual to employ silver contacts where high switching loads are encountered. Recently, however, the specifications for window lift switches have been upgraded and the prior switches fail to meet the requirements. Furthermore, the elimination of silver contacts is desirable to attain lower costs and to reduce consumption of this metal.  
 SUMMARY OF THE INVENTION The object of this invention is to provide a switch capable of switching and carrying high DC current at low cost (ie without use of precious metals). The switch described in the Abstract attains superior performance at low cost. Considerable contact pressure is attained, thus minimizing the detrimental effects of high current passing through a point of low contact pressure. Ap proximately 0.020 inch (0.5mm) wipe is attained on all three contacts this being adequate to break the contact free should it weld to the terminal as well as insuring clean contact surfaces.  
  This switch is designed to meet the needs for automotive window lift requirements which become severe when the window has been driven to its limit of motion. resulting in a locked rotor in the motor. In this condition the current typically reaches 37 amps DC. This is large enough to preclude use of many switches over a large number of operating cycles. The switch is shown paired one blade controlling the *up&#34; mode of the motor and the other controlling the down&#34; mode of the motor. The use of this invention is not limited to paired operation a single blade is useful for many uses and in some instances the N.C. terminal could be omitted.  
 DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section through one side of the switch with the parts normal.  
  FIG. 2 is similar to FIG. 1 but the switch is actuated to close the NO. circuit.  
  FIG. 3 is also similar to FIG. 1 but with the switch actuated in the opposite sense (at which time the other of the pair would close its N.O. circuit) resulting in increased contact force on the NC. terminal and wiping the blade on the N.C. and center terminals.  
 FIG. 4 is a partial, exploded perspective of the switch elements.  
  FIG. 5 is an enlarged fragmentary perspective with parts broken away to show the manner of mounting the switch in the door panel.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT The present device has two sides but is simpler to understand if the initial description is confined to one side of the switch which is an operative switch by itself. In FIG. 1 one half or side of the complete switch is illustrated.  
  The switch has a&#39;housing 10 in which three spaced terminals are mounted. These terminals are designated both 12,14,16 and NO M and NC respectively. The housing is divided by a partition or barrier 18 separating the switching on one side of the housing from the switching on the other side. This is an electrical barrier. Switch blade 20 is bent into a generally U shape with a short leg 22 and a long leg 24. The free end 26 of the short leg 22 is bent downwardly and rests on terminal 14 to function as the pivot of the blade. The short leg is slightly bent at 28 to form a surface adapted to engage terminal 16. The free end 30 of the long leg is bent down to overlie terminal 12. The actuator 32 has point 34 bearing against the long leg 24 of the blade 20 and has a rounded shoulder portion 36 which is received in a cylindrical cavity 38 in the housing cover 40 so as to, in effect. make the actuator pivot about the center of the curvature of the shoulder 36 (or cavity 38). This center lies on the centerline of the switch housing. The actuator point 34 bears against the resilient blade off center (to the right). Leaf spring 42 passes over the flat 44 on the upper portion of the actuator with the ends of the leaf spring bearing against the underside of the cover 40 at 45,46. The leaf spring, therefore, exerts a force returning the actuator to the normal position illustrated in FIG. 1.  
  The cover is secured to the housing 10 by suitable means such as sonic welding. The cover is provided with a slot 48 through which the actuator tab 50 projects. Handle 52 is pressed onto the tab 50.  
  In the position illustrated in FIG. 1 with the actuator point 34 engaging the blade to the right of pivot 26 (which is the normal position), the blade will contact the NC, (16) terminal. If the actuator is now moved to the left (bear in mind that when the actuator 32 moves to the left the handle 52 moves to the right) the vertical face 54 of the actuator will strike the tab 56 standing up vertically from the long leg 24. Prior to striking the tab, however. the actuator point 34 will be moving about its center of rotation and, therefore, closer to the pivot 26, thus forcing the end 30 of the blade downwardly into contact with terminal 12 (NO,) as shown in full lines in FIG. 2. After the free end of the blade contacts the terminal, the flat face 54 of the actuator will engage the tab and push against the tab as movement of the actuator is continued. This causes the blade to wipe across the terminal 12 as illustrated in dotted lines in FIG. 2. This wiping action keeps the contacts clean and breaks any welds that may be formed when switching high DC loads. When the handle 52 is released, the actuator is returned to the neutral position of FIG. 1.  
  If the actuator is moved to the right as in FIG. 3, the actuatorv point 34 will ride up the incline tab 58. Since the blade was already in contact with terminal NC no switching action is accomplished by this but, depending on the slope of the ramp, a lateral force may be transmitted to the blade causing the blade to slide on both terminals 14 and 16 with the beneficial results noted above. If the slope (curve) of ramp 58 matches the arc of actuator point 34 (as shown in FIG. 3 in full lines) there will be no wiping action. If the slope is greater, the point pushes the ramp and causes the blade to be moved to the right, causing the wiping action on terminals 14,16 (dotted in FIG. 3). If the slope is less (or the tab 58 eliminated) there is no wipe and the free end 30 of the blade will rise as the actuator moves to the right.  
  It will be appreciated that in H6. I there is an electrical path from terminal 14 through the blade to terminal 16. This is the normal condition. The same path is completed in H6. 3 while in FIG. 2 the electrical path is from terminal 14 to terminal 12 and the electrical connection to terminal 16 has been broken. In the specific use for which this switch was designed, the center terminal M is connected to a DC motor while terminal 16 is connected to ground. Thus in the normal position the motor is grounded. When the switch is actuated as in FIG. 2, however, the motor lead M is now connected to terminal 12 which is connected to the positive side of the automotive electrical system to energize the motor.  
  As noted above. this switch is designed to be used as a pair as illustrated generally in FIG. 4. It will be seen that the blades are oppositely disposed when viewed from one side but if one were to look at one side and then turn the switch around and look at the other, the  
 blades would appear the same. When the actuator 32 is moved in a given direction, it will, for example, close the circuit from NO, to M on the right side of FIG. 4 while maintaining the circuit from NC to M on the left side of FIG. 4. Motor mode No. l is actuated. Then when the switch is actuated in the opposite direction, motor mode No. 2 will be energized since terminal M is then connected to the positive terminal designated NO while the right side of FIG. 4 would merely main tain the grounding of motor mode No. 1.  
  Just one side of the switch can be used as a simple switch completing a circuit from 12 to 14 in which case terminal 16 would not be necessary. Or it could be used to break a circuit from 14 to 16. Or the unit shown in FIG. 1 can be used without the other side&#34; of the complete product.  
 We claim:  
 1. A switch comprising,  
 a housing,  
 spaced terminals mounted in the housing,  
 an electrically conductive resilient blade formed in a generally U shape having a long and a short leg with the end of the short leg pivoted on one terminal and the long leg normally overlying and spaced from the other (N.C.) terminal with the U bend in the blade being spaced from the said one terminal in the direction opposite that of said other terminal relative to said one terminal,  
 an actuator pivotally mounted in the housing and normally engaging the long leg of the blade at a point lying between said bend and an imaginary line from said pivot to the pivot center of the actuator,  
 movement of said actuator to move the point of contact of the actuator with the blade past said imaginary line to an active position being operative to force the free end of the long leg of the blade into contact with said N.O. terminal.  
  2. A switch according to claim 1 in which the long leg of the blade is provided with an upstanding tab which is engaged by the actuator when the actuator moves from its normal position to said active position whereby continued motion of the actuator after the blade end contacts said N.O. terminal is operative to force the end of the long leg to wipe across said other terminal.  
  3. A switch according to claim 1 including a third (N.C.) terminal mounted in the housing in proximity to the bend of the blade and normally engaged by the short leg of the blade when the actuator is in its normal position, said short leg being moved out of contact with said N.C. terminal when the actuator is moved to its active position and contact pressure between the blade and the N.C. terminal increasing when the actuator is moved from said normal position in the direction opposite the active position.  
  4. A switch according to claim 3 in which the long leg of the blade is provided with an upstanding tab which is engaged by the actuator when the actuator moves from its normal position to said active position whereby continued motion of the actuator after the blade end co&#39;ntacts said N.C. terminal is operative to force the end of the long leg to wipe across said other terminal.  
  5. A switch according to claim 4 in which the blade is provided with a second tab sloping upwardly from the long leg on the side of the actuator opposite the first or upstanding tab, the second tab being engaged by the actuator when the actuator is moved in said opposite direction whereby the contact pressure between the short leg and said N.C. terminal and the wiping motion of the blade across the N.C. terminal are increased as a function of the angle between the second tab and the blade.  
  6. A switch including a second blade and terminal arrangement as defined in claim 5 arranged alongside the arrangement of claim 5 but in the opposite sense whereby a single actuator acting on both blades is operative to close the NO. terminal in one switch when moved in one direction and to close the other N.O. terminal when moved in the opposite direction.  
  7. A switch including a second blade and terminal arrangement as defined in claim 1 arranged alongside the arrangement of claim 1 but in the opposite sense whereby a single actuator acting on both blades is operative to close the NO. terminal in one switch when moved in one direction and to close the other N.C. terminal when moved in the opposite direction.  
 8. A switch comprising,  
 a housing,  
 spaced terminals in the housing,  
 an electrically conductive resilient blade bent into a generally U shape with the free end of one leg pivoted on one terminal,  
 an actuator pivotally mounted in the housing and normally engaging the other leg at a point offset from the imaginary line connecting the center of the actuator pivot and the pivot of said blade, movement of said actuator to move the point of engagement with the blade through said imaginary line being operative to move the blade relative to said other terminal.