Abstract The motor subassembly is mounted in the housing with the motor leads dressed between the motor case and the housing and connected to the motor terminal and to a switch blade terminal and does not require grounding. The gear case somewhat divides the motor case to retain the coil while the motor case cover cooperates with the gear case to enclose and journal the gearing with the drive pinion projecting therebetween to drive the gear on the perimeter of the timing cam. The timing cam is journaled on the bushing extruded from the motor cover and in the aperture in the housing cover with the gear cluster extension projecting into and visible in the cam hub to afford visual verification of motor operation. The three switch blades are accurately located in the housing by tabs engaging locating cavities and the pivoted yoke has pads which space the two outside blades from each other. During the time between defrost cycles the No. 1 blade rides on the cam with the No. 2 blade engaging the No. 1 blade. When the No. 1 blade drops off the cam drop, the No. 3 blade engages the No. 2 blade and remains so engaged until the No. 2 blade drops off the cam. The tangential distance between the ends of blades No. 1 and No. 2 determines the duration of the cycle in combination with the rotational speed of the cam. All components are trapped by the assembly of the cover to the housing which is accomplished without fasteners. The great reduction in parts while completely enclosing the product results in a quiet, low cost, accurate timer which is easily serviced in the field by way of easy verification of operation.
A timer comprising a housing, a timing cam rotatably mounted in the housing having a slow rise-fast drop surface, motor and gear means rotating the cam, three switch blades mounted in the housing with their distal ends adjacent and biased towards the cam, the first of the blades being closest to the cam and always in engagement with the cam, the second blade being longer than the first so it engages the rise after the first blade drops at the fast drop portion of the cam until the second blade drops at the fast drop, a yoke member pivoted in the housing and having an arm projecting between the first and second blades and another arm projecting between the second and third blades with the second blade free to move freely between the arms and the arms serving to determine the minimum spacing between the first and third blades whereby the third blade is held out of contact with the second blade while the second blade is in contact with the first blade as the first blade engages the slow rise of the cam and the third blade is free to contact the second blade while the second blade is in contact with the cam.
Claim 2
Dependent Claim
205 words
A timer comprising a housing, a timing cam rotatably mounted in the housing having a slow rise-fast drop surface, motor and gear means rotating the cam, three switch blades mounted in the housing with their distal ends adjacent and biased towards the cam, the first of the blades being closest to the cam and always in engagement with the cam, the second blade being longer than the first so it engages the rise after the first blade drops at the fast drop portion of the cam until the second blade drops at the fast drop, a yoke member pivoted in the housing and having an arm projecting between the first and second blades and another arm projecting between the second and third blades with the second blade free to move freely between the arms and the arms serving to determine the minimum spacing between the first and third blades whereby the third blade is held out of contact with the second blade while the second blade is in contact with the first blade as the first blade engages the slow rise of the cam and the third blade is free to contact the second blade while the second blade is in contact with the cam.
Claim 3
Dependent Claim
62 words
A timer according to claim 1 in which the cam has a hollow hub and the motor and gear means includes a shaft projecting into the hub and having an end configuration which readily indicates whether or not it is rotating, said hub projecting through the housing whereby the hub and the shaft are clearly visible from the exterior of the housing.
Claim 4
Dependent Claim
26 words
A timer according to claim 2 in which the exposed end of the hub has a one-way driving configuration whereby the cam may be manually advanced.
Claim 5
Dependent Claim
58 words
A timer according to claim 2 in which the motor and cam means are enclosed in a casing mounted as a unit in the housing, said housing including a body and a cover, said cam being journaled on the casing and the cover, said cover including means for engaging and retaining the casing in position in the housing.
Claim 6
Dependent Claim
49 words
A timer according to claim 1 in which the proximal ends of the blades are mounted in slots in the housing wall, each proximal blade end having a tab sheared therefrom, each slot including a cavity receiving the tab whereby the distal end of the blade is accurately located.
Claim 7
Dependent Claim
22 words
A timer according to claim 5 in which the housing includes a cover which functions to retain the blades in said slots.