US3546410A

US3546410A - Electrical safety switch particularly useful with appliances having door-like members

Info

Publication number: US3546410A
Application number: US812702A
Authority: US
Inventors: Norberto Brighenti
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1968-04-05
Filing date: 1969-04-02
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08
Also published as: NL161606C; SE352906B; DE1916564A1; FR2005621A1; GB1252768A; JPS5519017B1; NL6905295A; DE1916564B2; NL161606B

Description

United States Patent [72] Inventor NOI'MQ BI'IIIIQI" 3,091,675 5/1963 Sholtes 200/6 l .62

[my Primary Examiner- Robert K. Schaefer l2] 1 P Assistant Examiner-M. Ginsburg [221 Med 1969 Attorneys- Harold Levine, Edward J. Connors, J r., John A.

xi m hcormed Haug, James P. McAndrews and Gerald B. Epstein Dallas, Texas a corporation of Delaware [32] Priority April's, I968 [33 Italy 1 WA ABSTRACT: A safety switch for controlling the deenergiza- [54] ELECTRICAL SAFETY SWITCH PARTICULARLY USEFUL WITH APPLIANCES HAVING DOOR-LIKE tion and energization of appliances when a certain parameter exists such as the complete closing of the appliance door comprising a housing mounting a pivotally mounted contact arm and a slide member which biases the contact arm toward or away from a stationary contact. The slide is connected to an operating lever which is caused to be moved by the movement of the appliance door upon closing thereof. The slide member is provided with a stop which precludes the contact arm from engaging the stationary contact when the slide member moves in a first direction or forward stroke in a first orientation but permits the contact arm to engage the stationary contact when moving in the opposite direction or return stroke in a second orientation. The contacts are in engagement only when the slide member is in the first portion of the return stroke which occurs only after the appliance door is locked.

PATENTED DEC 8 I976 SHEET '3 OF 4 ELECTRICAL SAFETY SWITCH PARTICULARLY USEFUL WITH APPLIANCES HAVING DOOR-LIKE MEMBERS BACKGROUND OFTHE INVENTION The present invention relates to a switch having a reciprocally mounted slide in which the energization and deenergization of the switch is dependent upon the movement and location of the slide. 1 v a It is often necessary to electrically operate a particular device only after the latter is. safely placed in a particular operating position, as for example an appliance with a door when operation of the device is permitted only after complete closing of the door. A common example of such an appliance is a washing machine.

In such appliances a small door is provided through which the articles of clothing to be washed are introduced. For

reasons of guidance or safety it is imperative that when the small door is open,'even if the control switch is in the starting position, the appliance cannot be energized and put in motion since it obviously would be very dangerous for a person who might operate it.

Further, some international rules require as a safety feature that the machine be energizable only when the door of the appliance is completely closed.

To satisfy this requirement a switch may be mounted inside the washing machine and controlled by an adjustable shaft fastened on the appliance door.

In generah'when the do or is closed a hook mounted on the door moves with it until a predetermined limit is exceeded which is characterized by' the passing of a small plate fastened on the washing machine beyond which it suddenly engages :with the said small plate thuslocking the door.

The position of the switch must be regulated very accurately because the connecting of the power, through the switch, must take place only at the moment at which the locking hook is about to pass the small plate fastened on the appliance and thus lock the door.

If the regulation is inaccurate it may happen that the switch is not-operated at all or that it is operated prematurely; i.e. before the door is completely shut.

In either case, with this system it is extremely difficult to achieve a perfect compliance'with the rules; that is, achieve operation only when the locking hook engages the small plate locking the door.

SUMMARY-OF THE INVENTION the energizing'of the switch in the desired position.

According to the present invention the switch for controlling the deenergizingand energizing of a circuit is characterized in that the energizing is effected during the phase in which an operating lever of the switch executes a return motion, and comprises: A housing in which is disposed a movable contact arm pivotally mounted on a support connected to a terminal; a sliding member equipped with biased bearing means for exerting pressure on the movable contact element, the sliding member being able to assume first and second orientations corresponding to its forward and return movement respectively; the sliding member being configured so that in its firstorientation which it assumes when resting it pushes'the movable contact element into the open position, and in its second orientation when moving forward retains the :movable contact element in the open condition; the arrangement being such that when at the beginning of the return stroke of the sliding member it reassumes the first orientation and permits the movable contact arm to energize the electric circuit andmaintains it in this position for a certain distance of the return stroke, the movable contact arm being returned'to FIGS. 3456 show intermediate phases during the energizing operation of the contacts.

FIG. 7 shows the switch according to the invention in the energized position.

FIG. 8 shows the switch during an intermediate phase of the deenergizing operation of the contacts.

FIGS. from 9 to 15 show the invention as used in a closing and locking device for washing machines.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF PREFERRED EMBODIMENT With reference to the drawings, terminal 1, shown as a pin connection but which instead could have a screw or welded end, is mounted inside a housing 2 of electrically insulating material with a contact ledge 3 and an integral plate 26 which serves to more effectively align the movable contact arm 5 along with

legs

8 and 9 of ledge 3 which extend through

slots

6 and 7 respectively formed on arm 5.

The terminal 10, also shown as a pin connection, mounts a stationary contact 11 inside housing 2.

The movable contact arm 5 is maintained in the open position by a small bearing member 12 which is biased against contact arm 5 by a spring 13 which is seated in a cavity 14 formed in the slide member 15.

Lever 32 projects from slide member 15 and serves as the element controlling the operation of the switch.

In FIG. 1 the force exerted by bearing member 12 on contact arm 5 follows an imaginary line along the arm 5 intermediate the

teeth

8 and 9 and with the

faces

17 and 18 respectively which are generally parallel parallelograms turned to the internal

generallyparallel side walls

19 and 20 of the cover and the base of housing 2 whichserve to define a guideway in which member 15 slides. I

From face 17 in continuation of tongue 21 (FIG. 2) projects a stop 22 which in FIG. 1 is pointed away from the side 23 of movable'contact arm 5.

A return spring member 24, only an end of which is shown but which is mounted in'any convenient manner, pushes the wall 25 of the slide member 15 against the wall 26 of the housing 2.

The

slots

27,28,29 merely facilitate the fabrication of the slide member by'means of a stamping operation.

When a member, a hook of a washing machine for example, exercises the control in the direction of the arrow of FIG. 3 the slide member '15'rotates about the center of the small bearing member 12 we second orientation with

faces

30 and 31 of slide member 15, also generally parallel parallelograms, bearing on the

internal side walls

19 and 20 of the guideway in housing2, FIGS. As shown in the drawings, face 18 intersects face 30 and face .31 intersects face 17. In this position the movable contact arm 5 has'not undergone movements while stop 22 has turned toward the contact arm 5 interposing itself in the path of the'movable contact arm.5 between the contact arm and stationary contact 1].

Continuing the movement of the lever 32 in slot 33 of the housing bearing member 12 when passing beyond pivot mounting ledge 3 pushes the movable contact arm 5 toward stationary contact '11 "but completion of this action is precluded by stop 22, as indicated in the FIGS. 4 and 5.

When the operating member after completing the first control stroke returns by only a certain amount, as in the case of 3 the hook of a washing machine which once the engaged position is reached moves with a snap action, the return spring 24 pushes the slide member IS from the position of FIG. 5 to that of FIG. 6 and then to that of FIG. 7.

During the movement from FIG. 5 to FIG. 6 the stop 22 moves away from the movable contact arm 5 permitting it to engage with stationary contact 11, and during the movement from FIG. 6 to FIG. 7 the slide member 15 stops against the member that has operated it maintaining contact arm 5 and stationary contact 11 in engagement with the apparatus energized.

When the hook of the machine is returned to release the door the device moves into the position of FIG. 8 and then into that of FIGS. 1 and 2.

In the initial position at a first extremity of the guideway the slide member 15 is biased into the first orientation FIGS. 1 and 2) when a sufficient force isexerted by a member (see arrow FIGS. 3, 5 and 6) toward the opposite second extremity of the guideway, slide member 15 moves into the second orientation (FIG. 3).

As the force continues slide member 15 slides in the guideway to the second extremity (FIG. 5), the contact arm bearing means 12 moves along with slide member 15 and upon passing by the pivotal mounting ledge 3 of the contact arm 5 intermediate the two extremities of the guideway, a contacts closing force is exerted on the movable arm; however, the pivoting of contact arm 5 is limited by the interposition of stop 22 which precludes contact arm 5 from moving into engagement with the stationary contact 11 while slide member 15 is in the second orientation.

After slide member 15 reaches the second extremity of the guideway the operating force diminishes to a point less than the return force exertedby spring 24 and the slide member returns to the first orientation (FIG. 6) removing the stop from the path of movement of contact arm 5 and permitting contact arm 5 to engage'stationary contact 11. The return force moves slide member 15 part of the way back toward the first extremity but short of the pivotal mounting. It will be seen that until member 12 moves to the other side of the pivotal mounting shelf 3, the contacts will remain in engagement.

Once operating lever 32 is moved toward the initial position beyond the pivotal mounting of the contact arm 5, the contact arm will be forced away from the stationary contact thus deenergizing the apparatus.

An illustrative example of an application of this switch is show in FIGS. from 9 to 15 in which is illustrated the switching device according to the invention associated with means for closing a washing machine including a hook (as seen in FIGS. 10, 12 and 14) attached to the washing machine door (not shown) and slide plate 34. Further, similar closing structure is described in copending and coassigned patent application Ser. No. 783,372 filed Dec. 12, 1968 to which reference may be had.

In this case, closing action of the washing machine hook causes plate 34 to move to the right as seen in FIG. 10, as the hook contacts the inclined tongue portion of plate 34. This motion is transmitted to the projection 32 through the sliding plate 34. Return spring member 35, which is an alternative form of spring compared to spring 24 shown in FIGS. 1, 3, 5 and 6, applies a force against plate 34 tending to move the plate to the left as seen in FIG. 10.

Costly regulations for the positioning of the control can be avoided with the above described switch since connection of the power source is allowed to take place only when the control member has returned and. precisely after the hook has moved from the position of FIG. 11 to the position shown in FIG. 13 and after to that of FIG. 15 where the hook has jumped into the position for the locking of the door. FIG. 10 shows this switch in the same position as in FIG. 7, FIG. 11 that of FIG. 2, FIG. 12 that of FIG. 5, FIG. 13 that of FIG. 4 and FIG. 15 that ofFIG. 7-

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. i

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above constructions b. a slide member slidable in the guideway between first and second extremities, the slide member and guideway include means which permit the slide member to assume first and second orientations;

c. a stationary contact mounted in the housing;

d. movable contact arm means including a movable arm movable in a path into and out of engagement with the stationary contact;

e. means for moving the slide member between the first and second extremities, the slide member assuming the first orientation when the slide member moves from the first extremity to the second extremity, the slide member ass'uming the second orientation when the slide member moves from the second extremity to the first extremity; and

. a stop member attached to the slide member and interposable in the path of the movable contact arm when the slide member is in the second orientation to prevent the engagement of the movable contact arm with the stationary contact.

2. A switch according to claim I in which the movable contact arm means includes:

a pivot ledge having two ends with a leg extending downwardly from each end, the ledge located above the guideway intermediate the first and second extremities;

two notches provided in the movable arm with each leg extending into a respective notch; and

spring biased bearing means forcing the arm against the ledge, the bearing means mounted on the slide member, the bearing means forcing the movable contact arm away from the stationary contact when bearing against the contact arm between the first extremity and the pivot ledge and forcing the movable contact ann toward the stationary contact when bearing against the contact arm between the pivot ledge and the second extremity.

3. A switch according to claim 2 in which an end of the movable contact arm is bifurcated and a plate is placed between the bifurcation which, cooperating with the ledge legs, keeps the movable contact arm in alignment.

4. A switch according to claim 1 in which the means for moving the slide member includes a lever extending from the slide member.

5. A switch according toclaim 4 further including a return spring which contacts the lever and biases the slide member toward the first extremity and the second orientation.

6. A switch according to claim 2 in which the ledge is attached to a terminal.

7. A switch according to claim 1 in which the guideway has opposed generally parallel sidewalls, the slide member being generally prismatic and having first and second faces which are generally parallel parallelograms and in the first orientation are generally parallel to the side walls, and having third and fourth faces which are generally parallel parallelograms and in the second orientation are generally parallel to the side walls, the first and third and second and fourth faces intersecting each other.

8. A switch for controlling the energization and deenergization of a circuit comprising: a housing, a pivotally mounted movable contact arm disposed in the housing, a support and a terminal mounted in the housing, the support electrically connected to the terminal, the contact arm pivotally mounted on the support; a slide member'having means for exerting a pressure on the movable contact arm, means permitting the slide member to assume first and second orientations corresponding to a forward and return stroke of the slide member respectively; the slide member being conformed so that in its first orientation which the slide member assumes when resting biases the movable contact arm into the open position, and in its second orientation when moving forward retains the movable contact arm in the open condition; at the beginning of the return stroke the slide member returns to the first orientation and operates the said movable contact arm to energize the electric circuit and maintains it in this position for a certain distance of the return stroke, the movable contact arm being returned to the initial open position by the pressure exerting means in correspondence to the final phase of the return stroke of the slide member. J

9. A switch according to claim 8 in which the movable contact arm is conformed so as to lie in a balanced arrangement in a seat provided on the said terminal, the center of rotation of the said balanced arrangement being disposed in a point intermediate between the extreme positions occupied by the slide member.

10. A switch according to claim 8 in which the said slide member is generally a prismatic body, a guideway is defined by side walls in the housing, and'the slide member is disposed in the guideway and assumes the two orientations correspond ing to the forward and return stroke respectively.

11. A switch according to claim 10 in which the prismatic slide member has a first and second pair of surfaces which enter alternatively in contact with the side walls of the guideway.

12. A switch according to claim 8 in which the means for exerting pressure on the movable contact arm comprise spring means which provide a biasagainst the movable contact arm.

13. A switch according to claim 8 in which the slide member includes a stop which limits contact closing movement of the movable contact arm when the slide member is in the first orientation. I

14. A switch according to claim 8 in which a control lever is provided in perpendicular relation to the axis of pressure on the movable contact arm and cooperates with the slide member.

15. A switch according to claim 8 in which longitudinal centering means is provided to align the movable contact arm.