US3798397A

US3798397A - Time delay switch having contact ram actuator and energy storage means

Info

Publication number: US3798397A
Application number: US00305248A
Authority: US
Inventors: E Awakowicz; A Geese; H Hoher
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1971-11-10
Filing date: 1972-11-10
Publication date: 1974-03-19
Anticipated expiration: 1991-03-19
Also published as: IT970257B; JPS4854480A; BE791256A; GB1389120A; NL7215044A; SE391065B; JPS5414301B2; DE2155916C3; AT319374B; NL153365B; LU66428A1; AR194516A1; FR2159313A1; BR7207871D0; DE2155916A1; FR2159313B1; CH550482A; DE2155916B2; ZA727792B

Abstract

A short time switch for carrying out switching operations of limited duration is described. The switch is actuated by, for example, a pushbutton, but the remainder of the switching operation is carried out automatically. A contact spring arrangement is provided upon which are mounted the switch contacts, and a force-proportional retarding element, associated with the contact spring, which controls the return time of the control spring arrangement to its original or rest position. A ram, operated axially by the pushbutton has a shoulder which engages with a free end of one of the contact springs. A cam, mounted on the ram, during the axial travel of the ram, causes it to disengage from the pushbutton at a given point. At the point of disengagement, further movement of the ram is under the impetus of an energy storage element, such as a leaf spring, and independent from the pushbutton.

Description

United States Patent [191 Geese et al.

TIME DELAY SWITCH HAVING CONTACT RAM ACTUATOR AND ENERGY STORAGE MEANS Inventors: Albert Geese; Herbert Hoher, both of Munich; Erwin Awakowicz, Bocholt, all of Germany Assignee: Siemens Aktiengesellschaft, Munich,

Germany Filed: Nov. 10, 1972 Appl. No.: 305,248

[30] Foreign Application Priority Data Nov. 10, 1971 Germany 2155916 [52] US. Cl. 200/34, ZOO/83 T [51] Int. Cl. H01h 7/03, HOlh 43/28 [58] Field of Search ZOO/34, 83 T; 335/61 [56] References Cited UNITED STATES PATENTS 1,937,173 11/1933 Taylor .f. 200/34 3,236,961 2/1966 Kappel 200/34 2,556,427 6/1951 Kaupert 200/34 3.585,321 6/1971 Dennison.... 200/34 3,551,615 Dennison 200/34 FOREIGN PATENTS OR APPLICATIONS 45,643 4/1932 Denmark 200/34 449,697 6/ 1949 Italy 200/34 Primary Examiner-James R. Scott 5 7] ABSTRACT A short time switch for carrying out switching operations of limited duration is described. The switch is actuated by, for example, a pushbutton, but the remainder of the switching operation is carried out automatically. A contact spring arrangement is provided upon which are mounted the switch contacts, and a forceproportional retarding element, associated with the contact spring, which controls the return time of the control spring arrangement to its original or rest position. A ram, operated axially by the pushbutton has a shoulder which engages-with a free end of one of the contact springs. A cam, mounted on the ram, during the axial travel of the ram, causes it to disengage from the pushbutton at a given point. At the point of disengagement, further movement of the ram is under the impetus of an energy storage element, such as a leaf spring, and independent from the pushbutton.

6' Cla s @Wie Figure Namam TIME DELAY SWITCH HAVING CONTACT RAM ACTUATOR AND ENERGY STORAGE MEANS BACKGROUND OF THE INVENTION The invention relates to short time switches for switching processes of limited duration. These switches can be initiated by an operating'means, such as a push button, and in which the switching operation subsequently is completed automatically.

Short time switches of this type are used to perform, with simple means, switching processes, e.g., making or breaking circuits, having a very short but accurately defined duration.

To be independent from the operating speed of an operating element, it has proved desirable to initiate a desired switching operation by actuating an operating element but to complete theprocess through the force of energy storage elements. The duration of the switching operation which is usually carried out by moving a contact spring, depends on the force of the driving storage and the inert mass of the contact spring to be moved. Toincrease the duration of the process, the contact spring to be moved is usually subjected to the action of a retarding means, e.g., in the form of a friction control device.

A dead-center spring bent in the form of a horse shoe is usually employed as an energy storage element for completing switching processes independently of the operator. It is so connected with the operating means and the contact spring assembly to be controlled in a manner such that it'can exert its force on the contact spring assembly from its starting position to a predetermined point of the'operating path in one direction, and after running through the force reversing position, its force is exerted in an opposite direction. At the moment of force reversal, a dead-center spring, so constructed, can relax independently of the operator. ln prior art short time switches and quick-action switches which operate the contact by a very quick nonrepetitive change of the switching condition, the relaxation movement is utilized to drive the switching operation (e.g., see GermanUnexamined and Published Patent application No. 1,255 723). g

It has been shown that, apart from the susceptibility to wear and tear and the great difficulty in replacing this type of dead-center spring, the independence from the operating speed, while provided in adequate measure, does not satisfy the demands of a short time switch with delayed contact movement.

The spring, which always remains connected at its two end points to its control elements, transfers its energy to the spring assembly from the moment of the force reversal. However, its other end, which is connected to the operating means, moves at the same time; namely, at any operating speed. Thus, the relaxation process does not take place between a fixed and a movable point, but between two movable points, and may naturally. result in two opposite directions.

The above relationship also exists in quick-action switches, which actuate the contact by a non-repetitive change of the switching condition. The very quick operation of the contacts is not endangered by this uncontrollable relaxing process. However, operating and switching speeds of short time switches with delayed operation may lie in ranges in which the mutual influence has an unfavorable effect on the desired interval.

A dead-center spring of conventional construction, if it has been brought over the dead center by means of a push-button like operating means and has jumped to its other end position, must return to its starting position over the dead center, so as to be prepared for a new switching operation. This return of the spring to its initial position, with renewed great stress on the material, is completely unnessary for the desired switching process, but contributes to the wear of the spring.

It is an object of the invention to provide a vshort time switch which is provided with a wear-resistent energy storage, wherein dependence of the switching speed on the operating speed is substantially avoided.

SUMMARY OF THE INVENTION- This object is achieved according to the invention by providing the short time switch with a ram having a shoulder which bears upon the free end of one of the contact springs. This ram can be moved by the operating means, which may be a pushbutton. A cam is provided, by which at a given point of its path of travel the ram can be disengaged from the operating means. The further motional action of the ram, which brings about the intended switching process independently of the aforesaid operating means, is influenced by the action of an unloading energy storage.

In a short time switch, so constructed, the low-mass intermediate member constructed like a ram between the operating means and the contact spring assembly can completely be detached from the driving operating means and moved further or returned to its initial position according to choice. Under the influence of a loaded energy storage the switching movement of this ram thus takes place completely independently of the movement of the operating means, in contrast with the dead-center spring.

In this connection, the ram can be arranged such that in one terminal area it is movable substantially in the direction of its longitudinal axis, and in its other terminal area it is also movable at right angles to the longitudinal axis. If, for example, it is carried with one end in a hole through a thin-walled material, these prerequisites are provided. The end of the ram which is carried in the hole is substantially movable in a longitudinal direction; the free end may additionally be swivelled at right angles thereto. In rest position, the ram may be in engagement with the operating means. The pivotability of the free end of the ram can be utilized by means of a cam which bears upon the ram when actuating the operating means for uncoupling the ram therefrom, so that the ram can be run back by the resetting force of the aforesaid energy storage to a rest position with respect to the operating means.

The arrangement of the ram in a hole between the operating means and the energy storage facilitates its replacement. Also, the ram need not be held under tension during the installation, in contrast with the deadcenter spring.

In contrast with the drive by means of a dead-center spring, the energy storage need only be tensioned and unloaded once to perform the switching operation. This, of course, is conducive to lessening on the wear and tear on the energy storage element in the switch. The resetting force acting on the ram may be applied by its own spring, which serves as an energy storage. When actuating the operating means, the energy storage can be loaded via the ram until it can move further and thereby bring about the switching process, as soon as it has been disengaged from the operating means. The energy storage may be constructed as a leaf spring having the length of a contact spring without requiring much space, so that it is only moderately stressed during the required working movement, in contrast with the arrangement for a dead-center spring. This construction also serves to lessen the wear and tear on the energy storage mechanism.

If the restoring force applied by this leaf spring acts on a shoulder of the ram so that the free end of the ram moves along a curved path under the influence of the decaying restoring force, and if, further, the ram is provided with an actuating shoulder in the area of its swivelling end, which is disposed such that on the return path it comes in contact with one of the contact springs, the ram can deflect one of the contact springs during its restoring movement. As a result of the curved path of the ram, the actuating shoulder is disengaged from the contact spring at a predetermined point of the restoring movement. From this moment, the contact spring moves to its initial position by virtue of its own elasticity.

The deflection of the contact spring naturally depends on an adequate dimensioning of the driving energy storage. Its movement from deflection to return to its rest position, may for example, be utilized to open the contact. The total opening time of the contact is composed of the times for deflection and restoring. If the actuated contact spring is coupled with a retarding means, the latter can be operative in one as well as in both directions of movement.

The construction and function of a short time switch according to the invention are still simpler, if one of the contact springs itself serves as an energy storage and produces the restoring force for the ram. To this end, the ram can deflect on its path, travelled by the operating means, the first and second contact spring of the spring assembly together without alternating the switching position of the contact spring assembly. If the ram is finally disengaged from the operating means under the influence of the cam, it can be restored to its initial position by at least one of the contact springs. If the retarding means acts on the second contact springs, the contact is opened at the moment of the return of the first contact spring producing the restoring force, since the second spring is not capable of following so rapidly. The slow-down time of the second contact spring, which is caused by the influence of the delaying means, determines in this case the duration of the contact break.

A pneumatic brake may be employed as a retarding means, wherein, by means of a piston or a membrane, a predetermined amount of air is driven through a nozzle. By varying the cross-section of the nozzle, for example, by means of an adjusting screw, the time for the passage of air can be regulated. It is possible to construct this pneumatic brake as a closed housing having two chambers, for example, separated by a membrane. When deflecting the membrane, an equalization of pressure takes place through a nozzle disposed in the membrane. A brake so constructed is protected from dust that may clog the nozzle. However, it may be influenced by fluctuations in temperature and air pressure, and is, therefore, only relatively suitable for the application according to the invention.

Another development of the invention has a chamber, which is in direct communication with the outside air and is provided with a filter to protect it from dust. The smallest cross-section of the regulating nozzle should always be at least as large as the openings of the filter tissue, so that the dust that gets into the tissue can leave the chamber without clogging the nozzle.

It is possible to install an excess pressure valve parallel to the nozzle in both types of pneumatic brakes. This nozzle renders the brake inoperative in one direction.

The utilization of this type of pneumatic brake in short time switches for telephone equipment depends on the selection of a suitable material for the membrane. The materials elasticity is not without influence on the delaying action of the brake. It is essentially a matter of selecting a membrane material whose properties remain substantially unchanged in the temperature and atmospheric moisture range in which telephone equipment in general must be serviceable.

A pushbutton may be provided as an operating means for the short time switch. However, the operation may just as well be effected via a rotary drive. A push button as a rotary drive must be provided with its own resetting spring, which restores the pushbutton to the initial position after actuation. The ram cannot perform'this function since it has been disengaged from the operating means during the operating run and has automatically moved forward. All components of the short time switch may finally be placed in a housing to protect them from dust, the housing only being provided with openings for the operating means and the passage of air to the pneumatic brake.

BRIEF DESCRIPTION OF THE DRAWINGS:

The principles of the invention will be described hereinbelow in greater detail with reference to the preferred embodiments shown in the drawings wherein:

FIG. 1 is a side, cross-sectional view of an exemplary short time switch constructed according to the invention.

FIG. 1a is a side cross sectional view of the FIG. 1 embodiment illustrating the relative displacement of the operating elements following depression of the operating pushbutton.

FIG. 2 is a side elevation of another embodiment of a short time switch in accordance with the invention.

FIG. 2a is a side cress sectional view of the FIG. 2 embodiment illustrating the relative displacement of the operating elements upon depression of the operating pushbutton.

DETAILED DESCRIPTION CF THE DRAWINGS In the two figures, like reference numerals denote like parts.

FIGS. 1 and la shows a first preferred embodiment of a short time switch provided with a ram 1, which has one terminal area 2 carried in a bore. The other end of the ram is in meshing engagement with an operating means 3, constructed in the form of a push button. The push button is a hollow cylinder closed on one end and having an axially parallel slot 4 in its circumference at its open end. Diametricallyopposite slot 4 is an opening 25 on the pushbutton, which unlike slot 4, does not aim at the edge of the pushbutton. The push button is nonrotatably mounted in the short time switch, and is under the influence of its own restoring spring 5. The cylindrical shaft of the ram, which has a clearance in the hollow cylinder, extends into the interior of the latter.

The ram has nose-

type shoulders

6 and 7 on its circumference, one being capable of coacting as a cam 6 with a rib 8 disposed in the housing of the short time switch. Another shoulder v7 serves to transfer the movement of the operating means 3 to the ram 1, coming into contact with the cam edge 9 of the operating means, when the button is pressed. The ram further has a lever-type shoulder 10 on the other end carried in the bore, on which can act a restoring spring 11.

By means of an actuating shoulder 12, the ram is capable of operating a contact spring assembly 13, which has a first leaf spring 14 connected by a stud 15 to a membrane 16 of a pneumatic brake and a second leaf spring which is urged against the first leaf spring and makes contact with it at its contact end. The conventional pneumatic brake shown in the drawing is closed outwardly and has two

chambers

17 and 18. By means of the membrane, air can be pressed through a nozzle 19 from one chamber into the other. The through-port of the nozzle can be varied by means of an adjusting screw 20.

This short time switch, according to the invention, operates as follows: Upon actuating the pushbutton 3 downwardly, the ram 1 at first moves in an axial direction. The end of the ram, which extends into the pushbutton, is then swivelled by the interaction of cam 6 and shoulder 8 at right angles to the axis. This causes the cam nose 7 on the ram to leave the cam edge 9 of the pushbutton. The force of the restoring spring 11, which acts on the lever-type shoulder 10, moves the ram in a direction contrary to the operating direction of the pushbutton. The nose 7 slides upwardly on inner wall 26 of the pushbutton until it falls into the opening 25, so that the end of the ram received in the hollow space of the pushbutton describes a curved path in its motion. The actuating shoulder 12 on the ram, which moves on the same curved path, which is shown in FIGS. 1 and 1a by the motion of point A, reaches under a first spring 14 of the contact spring assembly 13, which is closed in the example, and raises it against its restoring force, as well as against the force of the pneumatic brake from the second contact spring 27. When continuing the curved path, the actuating shoulder 12 is disengaged from the contact spring 14 at a predetermined point, which moves back to its initial position by its own force against counter to the force of the pneumatic brake which exerts a pulling force to slow the travel of contact spring 14 and delay its return to its starting position. The ram has in the meantime also moved back without delay to its initial position in an axial direction due to the influence of the restoring spring. It can straighten itself parallel to the axis for the first time by letting the nose 7 fall into opening 25 of the pushbutton, as soon as the pushbutton, too, is in its initial position, so that cam nose 7 is again in meshing engagement.

The second preferred embodiment of a short time switch shown in FIG. 2 does not have its own restoring spring for the ram. The restoring force is applied by one of the contact springs. The operation of this short time switch is different from the one previously described.

Upon actuation of the pushbutton 3, the ram 1 moves, at first, parallel to the pushbutton, and, subsequently, executes a swivelling movement due to the action of the cam 6. However, in rest position the actuating shoulder 12 of the ram is in meshing engagement with a first spring 24 of a contact spring assembly which is held in the mounting frame by means of contact springs insulated one from the other. Shoulder 12 transfers its movement to the first contact spring, and, by this spring, also to a second contact spring 21, which is connected with the membrane 16 of the pneumatic brake over a stud 15. The initial switching condition of the contact spring assembly is maintained during this movement. The momentthe actuating shoulder 7 of the ram is disengaged from the cam edge 9 of the pushbutton, it is driven back to its initial position by the first contact spring 24. The pushbutton has, similarly to the FIG. 1 embodiment, andaxially parallel slot 4 in its wall into which the shoulder 12 can penetrate upon movement of the ram. The spring 24 loses momentarily its contact with the second spring 21, since the latter is not capable of following the first contact spring so rapidly due to the influence of the pneumatic brake.

The brake shown in the drawing has only one chamber 17, which is connected with the outside air via a filter 22. The conical nozzle 19 can be adjusted by a conically tapered adjusting screw 20. An excess-pressure valve 23 is so arranged that the brake is operative only during the return movement of the second contact spring.

In the two preferred embodiments described above, the ram, which moves under the influence of the energy storage, is employed to break a contact. Obviously, it is possible that a spring assembly can also be activated with the short time switch according to the invention such that the contact is closed for an accurately determined amount of time.

The principles of this invention have been described herein in terms of two preferred embodiments. The described embodiments are only exemplary, and it is contemplated that numerous modifications in and changes to them may be made within the scope of the invention, as defined by the appended claims.

We claim:

1. Switch apparatus for switching operations of predetermined duration comprising:

Housing means for supporting and enclosing said switch apparatus,

contact spring means, including at least a pair of elongated spring members having corresponding ends clamped, but insulated one from the other, and having corresponding ends which are free and movable and prestressed for operation in a predetermined direction,

electric contacts mounted on said movable ends of said spring members, said spring members being arranged to move said contacts into and out of engagement, respectively, and the ends of the paths of said movable ends,

operating means,

ram means arranged to move from a starting position through a predetermined path and to have its motion initiated by said operating means, said ram means having a first shoulder arranged to engage at least one of said movable ends at a predetermined point on said path of said ram means and to cause an elastic deflection of said spring members,

cam means arranged to operatively engage said ram means at a predetermined point on said path of said ram means for causing said ram means to deflect and to disengage said shoulder means from said spring member and to disengage said ram means from said operating means, said spring members thereby being caused to elastically return to their undeflected positions,

path to return into engagement with said operating means.

3. The switch defined in claim 1 wherein said first shoulder is arranged to deflect one of said movable delay means operatively connected to at least one of ends as said ram means in returning into engagement said spring members for causing said spring member to return to its undeflected position in a predetermined period of time after the return of the other of said spring members and energy storage means arranged to make contact with said ram means at said predetermined point on said path of said rarn means where said first shoulder engages at least one of said movable ends and drive said ram means back to said starting point.

2. The switch defined in claim 1 further comprising:

a second shoulder arranged on said ram means to receive a driving force from said energy storage so that an end of said ram means follows a curved with said operating means.

4. The switch defined in claim 1 wherein one of said spring members forms said energy storage means.

5. The switch defined in claim 4 wherein said movable ends are arranged to be deflected simultaneously by said ram means without affecting the relative positions of said contacts.

6. The switch defined in claim 1 further comprising:

restoring spring means for said operating means for restoring said operating means to a rest position subsequent to initiating operation of said ram means.

Claims

1. Switch apparatus for switching operations of predetermined duration comprising: Housing means for supporting and enclosing said switch apparatus, contact spring means, including at least a pair of elongated spring members having corresponding ends clamped, but insulated one from the other, and having corresponding ends which are free and movable and prestressed for operation in a predetermined direction, electric contacts mounted on said movable ends of said spring members, said spring members being arranged to move said contacts into and out of engagement, respectively, and the ends of the paths of said movable ends, operating means, ram means arranged to move from a starting position through a predetermined path and to have its motion initiated by said operating means, said ram means having a first shoulder arranged to engage at least one of said movable ends at a predetermined point on said path of said ram means and to cause an elastic deflection of said spring members, cam means arranged to operatively engage said ram means at a predetermined point on said path of said ram means for causing said ram means to deflect and to disengage said shoulder means from said spring member and to disengage said ram means from said operating means, said spring members thereby being caused to elastically return to their undeflected positions, delay means operatively connected to at least one of said spring members for causing said spring member to return to its undeflected position in a predetermined period of time after the return of the other of said spring members and energy storage means arranged to make contact with said ram means at said predetermined point on said path of said ram means where said first shoulder engages at least one of said movable ends and drive said ram means back to said starting point.

2. The switch defined in claim 1 further comprising: a second shoulder arranged on said ram means to receive a driving force from said energy storage so that an end of said ram means follows a curved path to return into engagement with said operating means.

3. The switch defined in claim 1 wherein said first shoulder is arranged to deflect one of said movable ends as said ram means in returning into engagement with said operating means.

6. The switch defined in claim 1 further comprising: restoring spring means for said operating means for restoring said operating means to a rest position subsequent to initiating operation of said ram means.