Patent Publication Number: US-5896759-A

Title: Interlock with safety

Description:
BRIEF SUMMARY OF THE INVENTION 
     The invention relates to interlock mechanisms for clothes washing machines and the like where moving machinery is behind an access door or lid and the machinery must be turned off whenever the access door is opened. 
     The invention features a mechanical coupling mechanism linking an access door, a push-to-start button, and a switch controlling power to machinery behind the access door. Many interlock devices permit start of machinery by simply closing the access door. The coupling mechanism according to this invention applies power to the machinery only if the push-to-start button is pressed after the access door is closed and ensures against accidents such as an infant tumbling into the machinery enclosure while pulling the access door down after him. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 shows a clothes washing machine with a coupling according to the invention. 
     FIG. 2 shows schematically electrical circuitry of the clothes washing machine of FIG. 1. 
     FIG. 3 shows in cross section part of the frame and the coupling of the washing machine of FIG. 1, the view being from the side of the washing machine. 
     FIG. 4 shows the coupling of FIG. 3 as seen from the front of the clothes washing machine, the parts being in the position which they occupy when the access door of the washing machine is open. 
     FIG. 5 shows the coupling of FIG. 3 as seen from the front of the clothes washing machine, the parts being in the position which they occupy when the access door of the washing machine has been closed. 
     FIG. 6 shows the coupling of FIG. 3 as seen front the front of the clothes washing machine, the parts being in the position which they occupy when the access door of the washing machine is closed and the machinery is running. 
    
    
     DETAILED DESCRIPTION 
     An appliance such as the fabric washing machine 10 shown in FIG. 1 has access door 11 giving access to rotating machinery such as spin chamber 12 driven by motor 13. Controls 14 generally control application of power from mains 19 to washing machine components 18, and switch 15 particularly controls application of power to motor 13 through circuit 16. Push-to-start button 17 receives a mechanical input from an operator to start operation of spin chamber 12. 
     As shown more particularly in FIGS. 3 and 4, a mechanical coupling such as linkage 20 links access door 11 to switch 15 in circuit 16. Housing 21 supports electrical terminals 22 and 23. Movable contactor 24 is connected to terminal 22 and is biased to move to a position in which it does not connect terminals 22 and 23 and can be moved to a position in which it connects the terminals. 
     Actuator shaft 25 is supported on slide bearing 26 of housing 21 so that it can move toward and away from contactor 24 over a range; coupling rod 27 is supported on slide bearings 28 and 29 of housing 21 permitting linear motion of coupling rod over a range and in a direction at right angles to the motion of actuator shaft 25. 
     Actuator shaft 25 includes contactor bearing surface 30 facing toward and bearing on contactor 24, push-start surface 31 facing away from contactor 24, lock-out surface 32 on a first side of actuator shaft and facing toward contactor 24, and, on a second side of actuator shaft opposite the first side, lock-in surface 33 facing away from contactor 24, and pawl-hold-out surface 34 facing at right angles to lock-in surface 33. 
     Coupling rod 27 includes length adjustment sleeve 35 terminating in access door engagement surface 36, lockout key 37 positioned to face the first side of actuator shaft 25, pawl support 38, and pawl stop 39. 
     Pawl 40 is supported on pawl support 38 and includes pawl key 41 and pawl catches 42. Spring 43 biases lockout key 37 toward actuator shaft 25, and spring 44 biases pawl key toward actuator shaft 25. 
     The operation of the invention may be explained with reference to three states or configurations of the coupling designated as 0-0, 1-0, and 1-1, shown respectively in FIGS. 4, 5, and 6. With the access door open and switch 15 open (state 0-0), access door extension 45 does not engage the coupling rod; the actuator shaft is pushed by contactor 24 to the left (as shown in FIG. 3) and the coupling rod with its attached lockout key 37 and pawl stop 39 is biased by spring 43 downward (as shown in FIG. 3) so that pawl key 41 is pulled back from the actuator shaft, and lockout key 37 is advanced behind lock-out surface 32. This state is shown in FIGS. 3 and 4 show the various parts in the position of state 0-0. From this state the switch cannot be closed because the lockout key is in position to prevent motion of the actuator shaft to push the contactor to the closed position. The access door can, however, be closed to transfer to state 1-0. 
     With the access door closed and the switch open (state 1-0), access door extension 45 engages the coupling rod, pushing it upwards against the bias of spring 43 so that lockout key is withdrawn from behind lock-out surface 32 and the pawl, now free from the pawl stop, is pushed by spring 44 so that pawl key 41 is pressing against pawl-hold-out surface 34. The actuator shaft is pushed by contactor 24 away from the switch. The position of the parts in the 1-0 state is shown in FIG. 5. From the 1-0 state the access door can be opened to put the coupling back into the 0-0 state, or in the more usual sequence the push-to-start surface is pushed by an operator to close the switch and shift the coupling to state 1-1. 
     When in state 1-0 the push-to-start button is pushed, the actuator shaft is moved to close the switch and permit the pawl key to snap behind lock-in surface 33. This configuration, state 1-1, is shown in FIG. 6. From state 1-1 the coupling can be shifted to state 0-0 by opening the access door , but other changes of state are precluded. 
     The coupling of the invention thus permits an operator to control access to and application of power to machinery in a useful way while giving an operator no way to put the equipment in the dangerous state in which there is access to moving machinery, and further precluding transfer of the equipment from an initial state (0-0) to the operating state (1-1) with a single action.