Abstract:
An escapement mechanism for an appliance timer includes a cylindrically shaped driving member which is concentric with the axis of the appliance timer program wheel. One or more cam lobes providing camming surfaces are formed on an interior cylindrical wall of the driving member. A ratchet wheel is disposed for rotation within the driving member. The ratchet wheel is drivingly connected to the program wheel. A pawl having a ratchet wheel engaging tooth at one end and a cam follower at the other end is actuated by the camming surfaces on the driving member to cause the pawl to move a predetermined distance in a first direction, engage the ratchet wheel, and then return the same distance in the opposite direction to advance the ratchet wheel and the program wheel in response to rotation of the driving member.

Description:
BACKGROUND OF THE INVENTION 
     This invention deals with timers, and more specifically with appliance cycle timer control mechanisms and drive mechanisms. 
     As the variety of demands made upon modern appliances has increased, so have the requirements made upon appliance cycle timers. For example, modern washing machines capable of washing various types of synthetic fabrics must be able to follow relatively complex washing cycle instructions in order properly to wash such synthetic fabrics. Appliances must be capable of carrying out such cycles without being attended by an operator. 
     As the cycle timer requirements have become more complex and demanding, cycle timers have, of course, become more complex to manufacture, adjust and install in the appliances. This increased complexity has resulted in increased cost. Further, in order to house the necessary equipment to achieve the complex cycles demanded, it has been necessary either to increase the size of appliance timers or, if the external size of the timer is required to remain constant, to decrease the size of the various internal timer components. Such a decrease in size can result in more fragile timer internal components which are more susceptible to breakage during appliance operation. Additionally such small components are frequently more expensive to manufacture and assemble, further adding to appliance cost. 
     Miniaturization of many appliance timer components has also been limited by the increased demand which modern appliances frequently place upon such timer components as, for example, on-off switches. Many of the necessary switches in appliance timers are now required to carry higher currents than they have in past appliances due to the increased work which the appliances are required to do. For example, the larger washing machines of today must carry larger loads of washing through a number of washing and spinning cycles. The size of the wash load often requires that the electric motor used in the washer be a higher current motor. Motor current may have to be switched several times by on-off switches housed within the appliance timer during the washing cycle. 
     Accordingly, it is an object of the present invention to provide an appliance cycle timer which is simple and economical to manufacture, and which incorporates an ample amount of program timing capacity to provide the required complex cycling. 
     It is a further object of the present invention to provide such a cycle timer in which the cycle-controlling switches have sufficient capacity to handle the relatively high-current requirements of modern appliances, and yet remain simple and economical to manufacture. 
     It is a further object of the present invention to provide such a cycle timer in which connections to the various switches are readily accessible from outside the timer housing, allowing the switch components to be wired in various combinations to meet the cycle timing requirements of a multiplicity of applications. 
     An additional object of the present invention is to provide a timer for controlling the operating cycle of an appliance, the timer including first means providing a program wheel mounted for rotation, switching means for initiating the various portions of the appliance operating cycle, means for driving the first means to rotate the program wheel in a predetermined manner, the wheel having a plurality of concentric and continuous grooves in its surfaces, the bottom of each groove defining a program controlling surface, and means for following each program controlling surface, the following means being coupled to the switching means for controlling the operating cycle of the appliance, and each following means extending into its respective groove. 
     A further object of the present invention is to provide such an apparatus wherein the pole and throw members of each of the switching means are formed from lengths of resilient wire having proximal ends fixedly mounted in a terminal block and accessible from the outside of the apparatus housing so that the various switch members may be coupled to one another readily to adapt the timer to a particular timing application. 
     Another object of the present invention is to provide such an apparatus wherein the distal ends of the throw members of the switches are formed to provide the following means, which following means are retained in the grooves, the throw members being formed and mounted yieldably to urge the following means against the groove bottoms to maintain contact spacing and alignment. 
     It is a further object of the present invention to provide an appliance cycle timer wherein the first means is generally disc-shaped and provides two opposite, axially facing program wheel sides, each side being provided with a plurality of grooves. 
     Another object of the present invention is to provide such an appliance cycle timer including an escapement mechanism comprising a drive member rotatable about an axis and providing a camming surface, means for following the camming surface, means for urging the following means into contact with the camming surface, an output shaft, a ratchet wheel drivingly connected to the output shaft, a pawl for engaging the ratchet wheel, the pawl being coupled to the following means and actuable by the following means to move the pawl a predetermined distance in a first direction, then return the pawl the same distance in the opposite direction to advance the ratchet wheel and output shaft a predetermined amount in response to rotation of the drive member. 
     An additional object of the present invention is to provide such an escapement mechanism wherein the driving member is generally cylindrical and is rotatable upon its axis and the camming surface comprises at least one cam lobe extending radially inwardly and peripherally about the inner cylindrical wall of the driving member. 
     A further object of the present invention is to provide such an escapement mechanism wherein the ratchet wheel and pawl are disposed within the cylindrical driving member and the ratchet wheel and driving member are coaxial with the output shaft. 
     Another object of the present invention is to provide such an escapement mechanism wherein the means for urging the following means into contact with the camming surface is a cardioid spring having a loop disposed about the driving member axis of rotation to position the spring within the escapement mechanism, the ends of the spring resting against the following means for urging the following means radially outwardly against the camming surface. 
     Other and further objects of the present invention will become apparent to those skilled in the art to which this invention pertains by referring to the following description and the accompanying drawings in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of various elements of a cycle timer constructed in accordance with the present invention; 
     FIG. 2 is a fragmentary and sectioned rear elevational view of the cycle timer of FIG. 1; 
     FIG. 3 is a sectional view of the cycle timer of FIGS. 1-2 taken generally along section lines 3--3 of FIG. 2; 
     FIG. 4 is a fragmentary sectional view of a part of the timer taken generally along section lines 4--4 of FIG. 3; 
     FIG. 5 is a fragmentary sectional view of the portion of the timer taken along section lines 5--5 of FIG. 4; 
     FIGS. 6a and 6b are fragmentary views of parts of the timer illustrated in FIGS. 1 and 3; 
     FIG. 7 is a fragmentary partial sectional view of the timer taken generally along section lines 7--7 of FIG. 3; 
     FIG. 8 is a partial sectional view of the timer taken generally along section lines 8--8 of FIG. 3; and 
     FIG. 9 is a fragmentary partial sectional view of the timer taken along section lines 9--9 of FIG. 4. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, the appliance timer 10 of the preferred embodiment includes a housing 12 comprising a front half 14 and a rear half 18. Shown diagrammatically interiorly of the front face 20 of housing half 14 is a constant speed motor and gear train assembly 22. Motor and gear train 22 is actuated by applying line voltage to motor coil wires 24 to drive a gear 34 situated at the opposite end of a shaft 36. It will be appreciated that any number of constant speed motor assemblies may be used with the timer 10. The housing 12 and even the motor assembly 22 are axially elongated in the accompanying drawings to facilitate the showing of the components. 
     Gear 34 engages a constant speed drive ring gear 44 which lies adjacent the rearward interior face 46 of housing 12. Ring gear 44 is formed about the exterior periphery of a cylindrical drive member 48. Drive member 48 comprises a collar 52 which is rotatably received on a driven, or output shaft 54. Shaft 54 is generally centrally disposed within the housing 12 and runs from the front to the back thereof. Drive member 48 further includes a cylindrical wall 62 coaxial with shaft 54, a generally circular front end 58 and an open rearward end 60. 
     The coupling of the constant speed motor and gear train 22 through shaft 36 and gear 34 ensures that ring gear 44 and drive member 48 rotate at constant speed. 
     A ratchet wheel 66 having a front face 68 and its pawl 74 are enclosed between a rearward surface 70 of drive member 48 and housing surface 46. The proximal end 75 of pawl 74 engages one of the radially outwardly directed teeth 78 of ratchet 66. The distal end 79 of pawl 74 provides a cam follower 82. 
     Cam follower 82 is proportioned and designed to follow the camming surfaces 84 formed by a plurality of cam lobes 87 which extend radially inwardly from the interior of the generally cylindrical wall 62. The motion of pawl 74 as follower 82 rides against cam surfaces 84 is limited by a pin 88 which is attached to the distal end 79 of pawl 74 and extends through an elongated slot 90 in the rear housing half 18. 
     Follower 82 is urged against cam surface 84 by the ends 91 of a cardioid wire spring 92 having a loop 93 which positions the spring relative to shaft 54. The force exerted by spring 92 on follower 82 as the follower is forced radially inwardly of drive member 48 by cam surfaces 84 is substantially constant throughout the follower&#39;s motion. As a result, each time follower 82 is urged radially inwardly toward a peak 94 of cam surface 84, proximal end 75 of pawl 74 disengages from ratchet wheel 66, moves in a forward stroke illustrated by the dashed line representation of the pawl in FIG. 2 a constant, predetermined distance. Then, as drive member 48 advances in the direction indicated by arrow 95, follower 82 returns from peak 94 to its radially outward position at the base of lobe 87 allowing pawl 74 to complete a return stroke to the position, illustrated in solid lines in FIG. 2. As the pawl executes the return stroke, its proximal end 75 engages the next tooth in the clockwise direction of ratchet 66 as shown in FIG. 2. The ratchet 66 thus is turned a predetermined amount with each return stroke of pawl 74. Each return stroke of pawl 74 thus causes a predetermined amount of rotation of output shaft 54. 
     The escapement mechanism, including driving member 48, ratchet 66, pawl 74 and cardioid spring 92, thus serves both to reduce the rotation rate of the ring gear 44 to a desired rotation rate at output shaft 54 and to convert the constant speed of rotation of ring gear 44 to a stepwise rotation of shaft 54. 
     Rotation of ratchet wheel 66 is transmitted through shaft 54 to a program wheel 100 having two opposite, generally flat axially facing circular sides 102, 104. A plurality of concentric grooves 110a-c, 110d-f are formed into surfaces 102, 104 respectively. The grooves describe circles on surfaces 102, 104 concentric with shaft 54. As best seen in FIGS. 6a and 6b, follower end portions 120a-f of switch throws 124a-f, respectively, ride in grooves 110a-f, respectively. These throws are desirably resilient wire. Each of switch throws 124a-f has two poles 128a-f, 132a--f, respectively, associated therewith, which poles are also desirably made of resilient wire. As best illustrated in FIGS. 4, 5 and 8, the depths of the grooves 110a-f from surfaces 102, 104 to the groove bottoms 111 vary in steps. For example, the shallowest portions 111s of the grooves may be 0.015 inch, with the depth of the next step 111m being 0.055 inch and the depth of the deepest portion 111t of each groove being 0.095 inch. The axially and peripherally extending side walls of the grooves desirably hold and guide followers 120a-f so that the followers remain securely in the grooves and the throws of their respective switches 124a-f remain in alignment with their associated poles 128a-f, 132a-f. 
     As follower end portions 120a-f of the switch throws 124a-f, respectively, follow the groove bottoms 111, the throws move from, for example, positions contacting poles 128a-f, corresponding to the shallowest portions 111s of the grooves to positions in contact with neither of the poles 128a-f, 132a-f  corresponding to the intermediate depths 111m of the grooves, to positions contacting poles 132a-f, corresponding to the deepest portions 111t of the grooves. 
     Thus, the depth of a groove 110a-f determines whether its associated throw 124a-f is in contact with its pole 128a-f, its pole 132a-f or is in a neutral position between the two sets of poles and in contact with neither. The desired switching sequence for the switches may be provided by properly varying the depths of the various grooves. 
     The switch throws 124a-f and poles 128a-f, 132a-f are all mounted in a terminal block 134 which is located in the bottom of housing 12. The poles and throws all protrude through the block to provide terminals 135 providing access to all of the switches on the outside of housing 12. The throws 124a-f, of course, are all mounted in the block 134 so that the throws are biased in such a direction as to urge their followers 120a-f against the bottoms 111 of grooves 110a-f. Throws 124a-f and poles 128a-f, 132a-f may all be made of the same material. The throws and poles may be made from, for example, heavy gauge brass wire. The follower end portions 120a-f of throws 124a-f may preferably be formed in the distal ends of the lengths of wire from which throws are fabricated. Contact points 133 are attached to the distal ends of the throws and poles. The contact points may be made of suitably shaped pieces of silver or its alloys which may be attached to the poles and throws by any desired method, such as by soldering or welding. 
     It should be noted that in the embodiment illustrated in the FIGS., and especially in FIGS. 4 and 7, throws whose followers ride in adjacent grooves on either of surfaces 102, 104 are on alternate sides of the terminal block 134. This location scheme prevents the switches from being located too close together. 
     Referring now particularly to FIGS. 6a-b which show details of the follower end portions 120a, 120b of two throws, 124a, 124b respectively, it will be noted that shaft 54 is designed to turn in only one direction. Thus, all of followers 120a-f are shaped to take into account the different directions in which program wheel 100 moves relative to them (see direction arrows 95, 137, 139 of the FIGS.). As illustrated in FIG. 6a, follower 120a is formed to allow the follower to provide minimum resistance to motion of program wheel 100 in the direction indicated by arrow 137, the direction in which wheel 100 is driven by rotation of ratchet wheel 66. In FIG. 6b, follower 120b, which is located on the diametrically opposite side of wheel 100 from follower 120a, is formed in the distal end of throw 124b to present minimum resistance to movement of wheel 100 in the direction indicated by arrow 139. 
     A manual control and selector knob 140 is attached to a stem 141 which is slidingly received in a recess 142 at the forward end 143 of shaft 54. Knob 140 may be pulled outwardly from the front of housing 12. A secondary program wheel 144 is located inside of housing half 14 between front 20 and surface 102. Wheel 144 is attached to knob 140 and slides axially of shaft 54 with knob 140. A program groove 145 similar to grooves 110a-f, is located in the front surface 146 of wheel 144. A groove follower 147 formed in the distal end of a throw 148 of an on-off switch 149 rides in groove 146. Throw 148 may be formed from the same material and in the same manner as throws 124a-f. A pole 150, constructed in the same manner as poles 128a-f, 132a-f lies behind throw 148. Throw 148 and pole 150 are both mounted in the terminal block 134. When control and selector knob 140 is pulled outwardly from housing 12 the contact points 156 of the on-off switch make, energizing motor and gear train 22 and starting the cycle timer. When the knob 140 is pushed rearwardly of housing 12, the cycle timer is turned off. 
     A pair of pins 160 are attached to the rearward surface 151 of wheel 144 and protrude through a pair of holes 162 in wheel 100 when knob 140 is in either the forward or rearward position. Thus knob 140 may be manually turned, turning the program wheel 100 so that the appliance timing cycle may be initiated at any desired point. 
     Of course, additional grooves similar to grooves 110a-f may be cut into either or both of surfaces 102, 104. One such timer has been constructed in which eight grooves have been cut into each of sides 102, 104, thereby providing the control for sixteen double-pole single-throw switches. Additional grooves, such as groove 169 of FIG. 7, may be cut into front surface 58 of drive member 48 to increase the switch capacity of the apparatus. However, switches actuated by grooves in surface 58, such as switch 171 of FIGS. 3, 7 will be actuated at a somewhat faster rate than will those switches actuated by program wheel 100, since driving member 48 rotates at the same rate as ring gear 44 and program wheel 100 rotates at the substantially slower rate of ratchet wheel 66. 
     To prevent program wheel 100 from being rotated in the wrong direction (direction opposite that of arrow 95) by manual turning of knob 140, an anti-reverse brake mechanism 180 is provided. Mechanism 180 comprises a mounting stem 182 which projects rearwardly of housing 12 from the inside of front housing half 14. A brake shoe 184 is rotatably mounted on the distal end 183 of the stem. The working surface 186 of shoe 184 may be roughened better to prevent unwanted rotation of program wheel 100. A weak spring 188 may be attached between points 189 on shoe 184 and 190 on housing 12 to bias the shoe sufficiently to avoid interference with turning of program wheel 100 in the direction of arrow 95 but not sufficiently to bias working surface 186 out of contact with the periphery of wheel 100 so that rotation in the undesirable direction is prevented. It is relatively important that such rotation by prevented since the followers 120a-f are suitably shaped to accommodate rotation of wheel 100 in only one direction and to rotate wheel 100 in the opposite direction could result in damage to followers 120a-f. 
     It should further be noted that the appliance timer of the present invention may be driven by a stepper motor, with or without a gear train, instead of the constant speed motor and gear train 22 and escapement mechanism illustrated in the FIGS. Also, logic circuitry might be provided to generate the pulses necessary to drive a stepper motor. 
     It should further be noted that the proximal ends 135 of the poles and throws which protrude from terminal block 134 to the exterior of housing 12 are ideally suited to be wired to one another as desired, or to receive printed circuit boards. Various ones of the poles and throws may be wired together or electrically coupled by suitably generated printed circuits to achieve a number of different desirable switching patterns. 
     It is to be understood that the various parts illustrated in the FIGS. may be of different sizes than those here shown. Many of the parts have been expanded in size and particularly in thickness in the axial direction of timer shaft 54 better to illustrate the cooperation and relative locations of the various parts of the timer. It may be appreciated that a timer made in accordance with this specification and the appended claims may be quite narrow in the axial direction along shaft 54. The escapement mechanism is desirably axially narrow and, of course, the program wheel is axially narrow. The switch array is axially narrow. The timer is not only compact, but is also inexpensive to manufacture as compared to conventional appliance timers.