Timer blade arrangement

Abstract

The timer has switches including upper and lower passive blades and an active blade therebetween. The distal end of the lower passive blade has depending spacers which straddle the cam upon which the follower on the distal end of the active blade rides. The spacers reference the lower passive blade off the hub of the drum type program cam. The lower passive blade is provided with a rest or stop for the upper passive blade limiting downward movement of that blade. With precision molding, both passive blades are accurately referenced from the cam hub and the location of the follower which actuates the active blade is precisely located. Accuracy of switching is increased without increased precision in manufacture. Use of two cam tracks permits simultaneous actuation of the active and "passive" blades to effect faster switching. It is possible to provide a "make-make" arrangement instead of the double throw arrangement.

We claim: 
     
       1. A timer including a program member rotatable about an axis and provided with spaced cams, a switch fixed relative to the program member for actuation by a cam,   said switch including two blades the free ends of which are biased towards the program member,   a follower .Iadd.molded .Iaddend.on one of the blades engaging a cam whereby the cam actuates said one blade relative to the other,   follower means molded on the second blade engaging the program member to reference the second blade relative to the program member .Iadd.and to constrain the second blade against lateral movement.Iaddend..   
     
     
       2. A timer according to claim 1 in which the switch includes a third blade biased towards the program member, said follower means including a stop limiting movement of the third blade towards the program member.   
     
     
       3. A timer according to claim 2 in which said follower means engages a separate cam on the program member for actuation thereby. 
     
     
       4. A timer according to claim 1 in which the switch includes a third blade, said follower means including a stop engageable by said third blade to limit movement of the third blade.   
     
     
       5. A timer according to claim 4 in which the first blade is actuated by the cam to first engage the third blade and upon continued motion to move the third blade from said stop into contact with the second blade. 
     
     
       6. A timer according to claim 4 in which the follower means engages a separate cam track on the program member whereby the second and third blades are referenced by the separate cam track while the first blade is actuated by the first named cam, said first blade being engageable with either the second or third blades and the blades moving into or out of contact may be moved in the desired direction simultaneously to increase the speed of switching.   
     
     
       7. A timer including a program member provided with spaced cams for operating switches and means for rotating the program member, a plurality of switches fixed relative to the program member for actuation by respective cams,   each of the switches including a blade having its proximal end fixed and its distal end including a contact and spacer means .Iadd.molded on the blade and .Iaddend.engaging the program member so as to reference the contact relative to the program member .Iadd.and to constrain the blade against lateral movement.Iaddend.,   a second blade having its proximal end fixed relative to the first blade with its distal end including a contact and a depending follower .Iadd.molded on the blade and .Iaddend.engaging one of the cams on the program member,   the second blade being self-biased to urge the follower into engagement with the cam whereby the second blade is actuated in accordance with the configuration of the cam to open and close said contacts in a programmed sequence.   
     
     
       8. The construction of claim 7 including means confining the follower on the second blade against lateral movement whereby the follower is kept on its associated cam. 
     
     
       9. A timer according to claim 7 in which the program member is flat and said cams are concentric about the center of rotation of the program member, said switches being disposed in generally tangential relationship to the cams.   
     
     
       10. A timer according to claim 7 in which the program member is cylindrical with the cams axially spaced along the cylinder and the switches are disposed in generally tangential relationship to the cylinder. 
     
     
       11. Apparatus according to claim 7 in which said spacer means engages another cam on the program member whereby both blades may be actuated by their respective cams. 
     
     
       12. Apparatus according to claim 7 including an electrical barrier projecting from one of the blades between it and the adjacent blades of the adjacent switch a sufficient height to electrically shield the contacts associated with the first switch from the adjacent contacts. 
     
     
       13. Apparatus according to claim 7 in which the distal end of the first blade is provided with an upwardly projecting stop, a third blade having its proximal end fixed relative to the first and second blades and having its distal end overlying said stop and having a contact adapted to be engaged by the second blade contact,   said third blade being self-biased against said stop and movable upwardly therefrom in response to elevation of the second blade by the cam to close the second blade contact on the upper blade contact.   
     
     
       14. A timer according to claim 7 in which the follower on the second blade is generally disposed on the projected diameter of said program member. 
     
     
       15. A timer including a program member having spaced cams, an assembly of spaced switches fixed relative to the program member for actuation by the cams,   each of said switches including a blade having its free end self-biased towards said program member and including a spacer .Iadd.molded on the blade and .Iaddend.acting on the program member to reference the blade relative thereto,   second blade operatively associated with the first blade in a switch and having a depending follower .Iadd.molded on the blade and .Iaddend.biased into contact with the associated cam,   contacts on said blades which are opened and closed according to the configuration of the associated cam.   
     
     
       16. A timer according to claim 15 in which said spacer is part of an assembly molded on the end of the first blade, said assembly including an electrically insulative barrier disposed between the contacts of said switch and the contacts of an adjacent switch. 
     
     
       17. A timer according to claim 15 in which each said second blade follower engages its associated cam between means limiting lateral movement of the follower.