GB2067356A

GB2067356A - Time delay switches

Info

Publication number: GB2067356A
Application number: GB8038136A
Authority: GB
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1979-11-30
Filing date: 1980-11-27
Publication date: 1981-07-22
Also published as: DE3044730C2; IT1167305B; GB2067356B; FR2471660B1; DE3044730A1; IT8068823A0; FR2471660A1

Abstract

A time delay switch comprises an oil dash pot (9) containing a piston (21) of a magnetic-flux-responsive material; and a magnetic circuit comprising a permanent magnet (18) on a handle (8), the piston (21), fixed magnetic yokes (14, 15), movable magnetic yokes (16, 17) and an armature (20) movable in response to a change of magnetic flux due to movement of the piston (21). A moving contact plate (13) is linked to the armature (20) and disposed to touch the fixed contact plate (11). A case which contains the components is made of an insulative resin and has first and second integrally connected parts (101), (102) Figure 3 (not shown) of relatively larger and smaller depth. The deeper part (101) contains the dash pot (9) with the handle (8) cradably fulcrumed above it. The shallow part (102) contains connection terminals (24, 24c, 25, 25c) and may also contain an instant switch linked to the handle 8, the arrangement being used for the combined operation of a lavatory light and a ventilator having a delayed OFF function. <IMAGE>

Description

SPECIFICATION Time delay switches This invention relates to time delay switches.

Time delay switches are used, for example, to turn off a light several minutes after an operating member or handle of the switch has been moved to an OFF portion. Such switches are useful, interalia, for controlling corridor or staircase lights or lavatory ventilators.

Recently, such delay time switches have incorporated an oil dash pot as a time delay mechanism.

If such a time delay switch is designed to be of the same size as a single unit switch module for an ordinary home use wall switch for a mains power supply, then since the time delay mechanism using the oil dash pot delay means takes up a certain space in an enclosure case of the switch the enclosure case must be made very thin in order to afford as much room as possible for the time delay mechanism.

Such a thin enclosure case has to be made of a thermoplastic resin, since this has a higher durability against mechanical shock than a thermosetting resin. However, the thermoplastic resin has a lower temperature resistance and a lower electrical insulation than the thermosetting resin. Therefore, if the time delay switch has an enclosure case of thermoplastic resin, its durability is not sufficient.

According to the present invention there is provided a time delay switch comprising: a delay action means comprising an oil dash pot containing a piston of a magnetic-flux-responsive material disposed in an oil-filled cylinder; a magnetic circuit containing a permanent magnet mechanically linked to a handle and magnetically coupled to the piston, at least one fixed magnetic yoke, at least one movable magnetic yoke and an armature movable in response to a change of magnetic flux due to movement of the piston, the handle having projections on both sides thereof to act as a cradling shaft; at least one movable contact plate linked to the armature; at least one fixed contact plate disposed to touch the movable contact plate;; a case which contains the above-mentioned components and has at least one terminal connected to the movable contact plate and at least one other terminal connected to the fixed contact plate, the case being of an insulative resin and having a first part of larger depth and a second part of smaller depth, said first part and said second part being integrally connected to each other; and a pair of bearing plates of a non magnetic-fluxresponsive and shock and abrasion resistant material mounted at an upper part of said first part of the case, with the oil dash pot between them and cradably bearing said projections thereon; said first part of the case containing the oil dash pot which is fixed to a bottom part of the case, the handle which is cradably fulcrum on said upper part of said first part, and the movable contact plate and the fixed contact plate; and said second part of the case containing said terminals, to which electric wires are to be connected at the bottom of said second part of the case.

The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a switch constituting a first embodiment of the invention with a cover and a handle and attached components removed; Figure 2 is an exploded perspective view of the embodiment of Figure 1; Figure 3 is a partially fragmental side view of the first embodiment; Figure 4 is a side view of a principal part of a magnetic circuit of the first embodiment when the switch is in the OFF state; Figure 5 is a side view of the principal part of the magnetic circuit of the first embodiment when the switch is in the ON state; Figure 6 is a circuit diagram of the first embodiment; Figure 7 is a plan view of a second embodiment with a cover and a handle and attached components removed; and Figure 8 is an exploded perspective view of the embodiment of Figure 7.

Atime delay switch shown in Figures 1 to 5 has an enclosure case 1 that comprises a first part 101 of larger depth and a second part 102 of smaller depth.

The first and second parts 101,102 of the case 1 are integrally formed by moulding a thermo-setting synthetic resin. The first part 101 and the second part 102 are each of a size in plan view corresponding to the size of a single module of an ordinary home use wall switch for switching a mains power supply, so that the time delay switch can be mounted to occupy two unit module spaces of an ordinary home use switch holding box and switch holding frame therefor, which are usually designed for holding three or six modules of ordinary home use wall switches.

The first part 101, which has a larger depth, contains an oil dash pot 9 fixed on the bottom part of the case 1. The oil dash pot 9 has therein a plunger piston 21 made of a magnetic-flux-responsive substance such as iron and an impeding oil 50 contained in a cylinder. A compression spring 49 is preferably provided so as to push the plunger piston 21 leftwardly (as shown in the drawings) away from a pole piece 19 in order to accelerate restoration of the piston 9. A moving contact plate 13 is disposed above the oil dash pot 9, and a fixed end thereof is fixed to a terminal 6 disposed in the second part 102.

A moving contact 10 of the moving contact plate 13 is disposed facing a fixed contact 12 of a fixed contact plate 11, and a fixed end thereof is fixed to a common terminal block 25 in the second part 102.

The common terminal block 25 has the terminal 6 and a relay terminal 6a.

The time delay structure comprises, as shown in Figures 4 and 5: the oil dash pot 9; a permanent magnet 18 fixed to a handle or operating member 8, in the form of a rocker; yokes 16 and 17 fixed on opposite pole faces of the permanent magnet 18; an armature 20 fulcrumed by a fulcrum pin 32 at a part near the yoke 16 under the handle 8 movably at its moving end 202, the armature 20 being pushed rightwardly. i.e. away from the pole piece 19, by the moving end of the moving contact plate 13; a central yoke 14 fixed on a central part of the oil dash pot 9; and a restoration yoke 15 fixed on a left end part of the oil dash pot 9.

The time delay structure operates as follows.

When the handle 8 is positioned as shown in Figure 4, the moving contact 10 is pushed leftwardly by the armature 20 and thus breaks from the fixed contact 12, thereby turning the switch OFF. When, on the other hand, the handle 8 is positioned as shown in Figure 5, the armature 20 leaves the moving contact 10 by virtue of the force of a spring 201, which is held on a spring holder 206 and pushes a projection 205 rightwardly, thereby ailowing it to make with the fixed contact 12 to turn the switch ON. The principle of such movement is that, when the handle 8 is in the position of Figure 5, the magnetic flux of the permanent magnet 18 flows in a magnetic circuit comprising: one pole of the permanent magnet 18 --the yoke 16 --- the central yoke 14 --- the plunger piston 21 --- the restoration yoke 15 --- the other pole of the permanent magnet 18.Since the magnetic flux is short-circuited by the plunger-piston 21 in this ON state, the armature 20 has no magnetic flux flowing therein and the armature 20 is therefore pushed rightwardly by the spring action of the spring 201, whereby the moving contact 10 makes with the fixed contact 12 thereby turning the switch ON. Switching OFF is effected by turning the handle 8 anticlockwise from the position shown in Figure 5 to the position shown in Figure 4, whereby the magnetic circuit is switched to disconnect the yoke 17 from the restoration yoke 15.By disconnecting the restoration yoke 15 from the yoke 17, the magnetic flux flowing between the central yoke 14 and the restoration yoke 15 through the plunger piston 21 is cut off, and the magnetic flux changes its flow to a path through a magnetic circuit comprising: the permanent magnet 18---theyoke 16---thearmature20---a gap between the moving end tip 202 of the armature and the pole piece 19 --- the pole piece 19 of the oil dash pot 9 --- a narrow extended part 211 of the plunger piston 21 --- the plunger piston 21 --- the central yoke 14---theyoke 17---the permanent magnet 18. By means of this flux, the plunger piston 21 travels rightwardly against the action of the spring 49. The plunger piston 21 moves at a slow speed because its movement is impeded by the oil 50.After several minutes, the plunger piston 21 reaches the pole piece 19. Then, by virtue of the end tip of the plunger piston 21 touching the pole piece 19, the reluctance between the pole piece 19 and the armature end tip 202 increases greatly, whereby the armature 20 is attracted to the pole piece 19. The resultant leftwards motion of the armature 20 drives the moving end of the moving contact plate 13 leftwardly and makes the moving contact 10 break from the fixed contact 12, thereby to turn the switch OFF. The moving contact plate 13 is formed to have a U-shaped bent part 23 so as to have a spring action by virtue of which the switch is normally on unless the contact plate 13 is pushed leftwardly by the armature 20 at its attracted position.

A terminal 24a is disposed near a terminal 24 and is isolated therefrom. An instant action switch, which is operated to switch on or off instantaneously with movement of the handle 8, is formed by a snapaction moving contact 38 disposed on a fulcrum 39 of an extended part of the terminal block 25 and a fixed contact 41 disposed on an extended part of the terminal 24a. The snap action mechanism is provided by engaging the moving contact 38, which is fulcrumed on a metal fulcrum 39, to one end of a compression spring 45, whose other end is linked to a driving bar 43 projecting from the handle 8. The metal fulcrum 39 is disposed on the bottom face of the shallower second part 102 of the case 1.The instant action switch it switched ON simultaneously with the switching ON of the time delay switch formed by the contats 10 and 12 upon clockwise movement of the handle 8, and is switched OFF simultaneously with the reverse operation (anticlockwise movement) of the handle 8, apart from and thus prior to the switching OFF of the time delay switch.

The terminals 24, 24a and 6 are spring-lock type terminals, each of which comprises a C-shaped locking spring 26 which locks an end tip part of a lead wire inserted therein through holes in the case bottom. The common terminal block 25 is further provided with an auxiliary locking spring 26 for constituting the relay terminal 6a. Numerals 27 and 27' designate unlocking elements which are pins made of insulating plastics and which function to push the locking springs 26 by plying them, thereby fastening end tips of the lead wires from the terminals 24, 24a, and 6a. The unlocking can be effected by plying the unlocking element 27 to the centre of the case and pulling down the lead wires.

The handle 8 is made of a translucent plastics substance and has projections 801, forming a shaft, on opposite side faces thereof. A pair of bearing plates 805 is provided in the first part 101 to receive the projections 801. The bearing plates 805 are made of a shock and abrasion resistant material for durability, but should be of non magnetic-fluxresponsive material in order not to disturb the magnetic flux of the magnetic circuit. A suitable material is, for example, brass plate. The bearing plates 805 are mounted on opposite sides of the oil dash pot 9 by inserting legs 806 thereof into holes 109 in walls and in a column 108 of the case 1.

Bearing cut-outs 807 of the bearing plates 805, for receiving the projections 801, may be semicircular recesses, since the upper sides of the projections 801 can be held in place by the lower face of a lid or cover 7 of the case 1. Since the bearing plates 805 are made of a strong material such as metal, the durability of the handle bearing is increased and the lifetime ofthe switch becomes longer; furthermore, due to the stable bearing provided by the strong bearing plates, a highly stable time delay motion is attainable.

A small glow discharge lamp 28 of very small power consumption, such as a neon lamp, is disposed under the handle 8 in such a manner that light from the lamp illuminates the handle from its lower face and the light diffuses through the translucent body of the handle so that the user can easily find the handle in the dark. In order to ensure illumination of the handle 8 by the neon lamp 28, an opening 32 is formed at the top part of the armature 20. The neon lamp 28 is connected in series with a resistor 29 between the moving contact plate 13 and the terminal 25.

The cover 7, which is of an insulative substance, has an opening 30' in a handle receiving projection 30 and is disposed on the case 1 in a manner to expose the upper face of the handle 8 through the opening 30'. A handle cover 33 of a transparent substance is provided on the handle 8.

A magnetic shield plate 35 of iron or another ferromagnetic substance is provided to surround the first part 101 of the case, in order to prevent spurious or incorrect operation of the delay means by an external magnetic field. A pair of metal fastening bands 34 are provided to fix the cover 7 and the magnetic shield 35 to the case 1. As has been explained, the case 1 of the present delay switch is such as to occupy two unit module spaces of an ordinary home use type wall switch for switching a mains power supply. There is therefore sufficient room inside the enclosure case 1 and there is therefore no need to make the wall and bottom of the enclosure case thinner than ordinary switches so as to contain the time delay mechanism.Therefore, it is possible to use a thermosetting synthetic resin for the enclosure case, thereby ensuring a higher insulation characteristic and higher temperature resistance than for a thermoplastic resin, which has to be used when only a small thickness of the case wall is allowable. Furthermore, by using two unit switch module spaces for the parts 101 and 102, it becomes possible to form a relaying or connecting terminal 5a which could not be formed if the time delay switch were structured only to occupy a single switch module unit.

A circuit diagram of the above-described embodiment is shown in Figure 6, wherein the chain-dotted block shows the switch embodying the present invention, a lamp A is connected to the switch via the instant switch terminal 6a and a lavatory ventilator B is connected to the switch via the moving contact terminal 6. E designates an AC power source. The time delay switch, controlled by the oil dash pot 9, belatedly opens the ventilator circuit. Therefore, the ventilator B will evacuate lavatory smells after switching OFF of the lamp A.

Figures 7 and 8 show a second embodiment wherein the structure in the first part 101 (time delay switch part) is substantially similar to that of the first embodiment, but the structure in the second part 102' (terminal part) is different in that the second embodiment has only a pair of terminals 24c and 25c and there is no moving contact 38 and no driving bar 43. The first terminal 24c is for connecting the moving contact plate 13 to an exterior electric wire and the second terminal 25c is for connecting the fixed contact plate 11 to exterior electric wires. Each of the terminals 24c and 25c comprises a pair of wire grasping springs, so that both terminals can serve as relaying terminals.

The time delay switch of the second embodiment has a single circuit time delay switch, and can be used for example in a lighting circuit for a corridor, staircase or entrance hall. The neon lamp 28 illuminates the handle 8 so that the user can easily find the handle 8 in the dark, when a lamp to be switched by the time delay switch is turned off.

Claims

1. A time delay switch comprising: a delay action means comprising an oil dash pot containing a piston of a magnetic-flux-responsive material disposed in an oil-filled cylinder; a magnetic circuit containing a permanent magnet mechanically linked to a handle and magnetically coupled to the piston, at least one fixed magnetic yoke, at least one movable magnetic yoke and an armature movable in response to a change of magnetic flux due to movement of the piston, the handle having projections on both sides thereof to act as a cradling shaft; at least one movable contact plate linked to the armature; at least one fixed contact plate disposed to touch the movable contact plate;; a case which contains the above-mentioned components and has at least one terminal connected to the movable contact plate and at least one other terminal connected to the fixed contact plate, the case being of an insulative resin and having a first part of larger depth and a second part of smaller depth, said first part and said second part being integrally connected to each other; and a pair of bearding plates of a non magnetic-fluxresponsive and shock and abrasion resistant material mounted at an upper part of said first part of the case, with the oil dash pot between them and cradably bearing said projections thereon; said first part of the case containing the oil dash pot which is fixed to a bottom part of the case, the handle which is cradably fulcrumed on said upper part of said first part, and the movable contact plate and the fixed contact plate; and said second part of the case containing said terminals, to which electric wires are to be connected at the bottom of said second part of the case.

2. A time delay switch according to claim 1, comprising an instant motion switch operable by said handle, thereby constituting two interlocked switches which operate simultaneously in one direction and operate at two different times in the other direction.

3. A time delay switch according to claim 1, wherein: said second part of the case contains a common terminal at one end thereof, two other terminals at another end thereof and an instant motion switch between said two ends; two contacts of the instant motion switch are connected between said common terminal and a first one of said two other terminals; a driven point of the instant motion switch is connected to a driving point of an interlocking bar connected to the handle; and one of the fixed contact plate and the moving contact plate is connected to the common terminal and the other one thereof is connected to the second one of said two other terminals.

4. Atime delay switch according to claim 1, claim 2 or claim 3, wherein said handle is of a translucent substance, the armature has an opening therein, and a glow discharge lamp is disposed underthe handle in a position to emit light through said opening to the handle.

5. A time delay switch according to any one of the preceding claims, wherein the bearing plates are of a non magnetic-flux-responsive metal plate and have bearing seats to receive said projections of the handle.

6. A time delay switch substantially as herein described with reference to Figures 1 to 6 of the accompanying drawings.

7. A time delay switch substantially as herein described with reference to Figures 7 and 8 of the accompanying drawings.