GB2227363A

GB2227363A - Push button switch

Info

Publication number: GB2227363A
Application number: GB8827763A
Authority: GB
Inventors: George Fewell
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-11-28
Filing date: 1988-11-28
Publication date: 1990-07-25
Anticipated expiration: 2008-11-28
Also published as: GB8827763D0; GB2227363B

Abstract

A push button switch 2 comprises a body part 4 with a bore 6 (Fig. 2), a push button member 8 slidably mounted in bore 6, a spring loaded switch device 10 which connects to body part 4 and biases push button member 8 to return to a set outer position after manual depression, and a self-locking washer 12, body part 4 having a plain outer surface 14 over which the self-locking washer 12 slides in order to secure the switch in a mounting panel 18. Rubber washer 52, or a flat 56 (Figs. 7, 8) counters rotation of the switch. Washer 52 also inhibits moisture ingress and pushbutton 8 fitting flush with face 26 (Fig. 4) of part 4 inhibits corrosion and vandalism. Pushbutton 8 inner/outer positions are determined by pin 20 engaging opposite sides of aperture 24. <IMAGE>

Description

A PUSH BUTTON SWITCH This invention relates to a push button switch.

Push button switches are well known. They are used to make a desired electrical connection. The push button switches are often mounted in groups on a mounting panel where individual switches can then be used to make desired individual electrical contacts, for example to different flats in a block of flats or to different floors in a block of flats serviced by a lift. The known push button switches are of a complex design. They tend to have a relatively large number of different parts which firstly require producing and which secondly require assembling together. The production and assembly of these different parts makes the switches awkward to produce. In addition, the known switches are often not easy to fit to a mounting panel.

It is an aim of the present invention to reduce the above mentioned problems.

Accordingly, this invention provides a push button switch comprising a body part, a bore in the body part, a push button member which is mounted in the bore such that the push button member can slide backwards and forwards in the bore, a spring loaded switch device which connects to the body part and which biases the push button member such that the push button member is caused to return to a set outer position after it has been manually depressed to an inner position, and a self-locking washer, the body part having a plain outer surface over which the self-locking washer slides in order to secure the push button switch in a desired aperture in a mounting panel.

The push button switch of the present invention has only a small number of parts so that manufacturing and assembly costs are facilitated. In particular, the use of the self-locking washer provides an easy way of securing the push button switch in the aperture in the mounting panel. For example, if the self-locking washer were replaced by a nut, then the body part would have to have a screw threaded outer surface instead of its plain outer surface. The threading of the body part to give the threaded outer surface would constitute an extra manufacturing step and it would take longer to thread the nut over the threaded surface of the body part than it does to slide the self-locking washer over the plain outer surface of the body part.

Preferably, the push button switch includes stop means for controlling the inward travel of the push button member. The stop means is preferably also for controlling the outward travel of the push button member.

When the stop means controls both the inward and the outward travel of the push button member, then the push button switch is advantageously one in which the stop means comprises a pin which locates in a first aperture in the push button member and in a second aperture in the body part, the pin being fixed in the first aperture, and the second aperture being larger than the first aperture so that the inner and the outer positions of the push button member are determined by the pin engaging on opposite side portions of the second aperture.

Advantageously, the second aperture is of such a size that the outer position of the push button member is always flush with a face of the body part. This ensures that the push button switch is less likely to become defective due to environmental corrosion and vandalism. More specifically, if the outer position of the push button member is such that the push button member is inset with respect to the face of the body part, then moisture and salt in a coastal environment tend to get inside the push button switch and cause corrosion. If the outer position of the push button member is such that the push button member extends beyond the face of the body part, then vandals may tend to slip knives between the push button member and the face of the body part to try and lever the push button member out of the bore in the body part.

Preferably, the pin is a rolled spring metal pin.

Usually, the body part and the push button member will both be circular is cross section. The push button switch may then be one in which the bore has first, second and third sections of progressively decreasing diameter, and in which the push button member has first and second sections of progressively decreasing diameter, the first and second sections of the push button member being such as to fit in the first and the second sections of the bore.

The spring loaded switch device may have a plastics housing and a pair of electrical contacts.

The self-locking washer may be a washer having inwardly flexing finger members.

The push button switch may include rotation preventing means for preventing rotation of the push button switch in the mounting panel. The rotation preventing means helps to combat vandalism since, if the push button switch is able to rotate with respect to the mounting panel, then vandals tend to try and rotate the switch which can cause electrical wires leading from the switch to twist and either short or snap.

The rotation preventing means may be a rubber washer for locating over the body part between the self-locking washer and the mounting panel. Alternatively, the rotation preventing means may be a flat on the side of the body part, the flat being such as to correspond with a complementary flat on the aperture in the mounting panel.

The present invention also extends to the combination of the push button switch and the mounting panel.

The combination of the invention will usually be such that there are a plurality of the push button switches mounted in the mounting panel.

When there are a plurality of push button switches mounted in the mounting panel, then the switches may be allocated numbers, for example flat numbers or building floor numbers. These numbers may be provided on the mounting panel or on the push button switches.

The numbers will usually be engraved or moulded, but they can be formed by other means if desired.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is an exploded view of a first push button switch; Figure 2 is a cross section through the body part of the push button switch shown in Figure 1; Figure 3 is an end view of the body part shown in Figure 2; Figure 4 is a partial cross section through the assembled push button switch, the switch being in an electrically open position; Figure 5 is a cross sectional view like the view shown in Figure 4 but with the push button switch in an electrically closed position; Figure 6 shows a plurality of the push button switches mounted in a mounting panel; Figure 7 shows an alternative body part; and Figure 8 is an end view of the body part shown in Figure 7.

Referring to Figures 1 to 5, there is shown a push button switch 2 comprising a body part 4, a bore 6 in the body part 4, and a push button member 8 which is mounted in the bore 6 such that the push button member 8 can slide backwards and forwards in the bore 6. The push button switch 2 further comprises a spring loaded switch device 10 which connects to the body part 4, and which biases the push button member 8 such that the push button member 8 is caused to return to a set outer position as shown in Figure 4 after it has been manually depressed to an inner position as shown in Figure 5. The position shown in Figure 4 is with the push button switch 2 being electrically open, and the position shown in Figure 5 is with the push button switch 2 being electrically closed.

The push button switch 2 further comprises a self-locking washer 12. The body part 4 has a plain outer surface 14 and the self-locking washer 12 slides over the plain outer surface 14 in order to secure the push button switch 2 in a desired aperture 16 in a mounting panel 18.

The push button switch 2 includes stop means in the form of a rolled spring metal pin 20. The pin 20 is for controlling the inward travel of the push button member 8, and also for controlling the outward travel of the push button member 8. More specifically, the pin 20 locates in a first aperture 22 in the push button member 8 and in a second aperture 24 in the body part 4.

The pin 20 is fixed in the first aperture 22. As can be seen from Figure 1, the second aperture 24 is larger than the first aperture 22 so that the inner and outer positions of the push button member 8 are determined by the pin 20 engaging on opposite side portions of the second aperture 24. This is clearly illustrated in Figures 4 and 5 wherein the pin 22 is shown engaging on the left side of the second aperture 24 in the switch open position shown in Figure 4, and the pin 20 is shown engaging on the right side of the second aperture 24 in the switch closed position shown in Figure 5.

Figure 4 also illustrates that the second aperture 24 is of such a size that the outer position of the push button member 8 is always flush with a face 26 of the body part 4. This provides a good anti-vandal feature. More specifically, if the push button member 8 were to extend beyond the face 26, then vandals could slide knives on to the push button member 8 or between the push button member 8 and the face 26 to prize the push button member 8 out of the body part 4. The flush fitting of the push button member 8 with the face 26, also avoids moisture and salt from a salty sea atmosphere getting into the inside of the switch as would likely be the case if the push button member 8 terminated short of the face member 26. Such moisture and/or salt would tend to cause corrosion inside the body part 4, leading to premature failure of the push button switch 2.

As can be seen from the drawings, the body part 4 and the push button member 8 are both circular in cross section. The bore 6 has first, second and third sections 28,30,32 respectively which are of progressively decreasing diameter. The push button member 8 has first and second sections 34.36 respectively which are also of progressively decreasing diameter. The first and second sections 34,36 of the push button member 8 are a close sliding fit in the first and the second sections 28,30 of the bore 6. The decreasing diameters of the sections 34, 36 and 28, 30 ensure that the push button member 8 cannot be knocked through the back of the mounting panel 18, The spring loaded switch device 10 has a plastics housing 38 and a pair of electrical contacts 40,42.The electrical contacts 40,42 are in the form of blades over which electrical connectors (not shown) can be pushed.

The spring loaded switch device 10 has a reduced diameter threaded portion 44 which screws into the third section 32 of the body part 4. This third section 32 is internally screw threaded with threads 46 so that the spring loaded switch device 10 can be screwed tightly into the body part 4.

The spring loaded switch device 10 has a spring loaded contact end 48 which is biased outwardly by springs (not shown) located inside the plastics housing 38. The contact end 48 engages the push button member 8 as shown in Figures 4 and 5. When the push button member 8 has been manually pushed in to the switch closed position shown in Figure 5, a cylindrical portion 50 of the spring loaded switch device 10 gets pushed into the plastics housing 38.

When pressure on the push button member 8 is released, the spring in the plastics housing 38 pushes the push button member 8 back to the position shown in Figure 4, the pin 20 engaging with the left hand side of the second aperture 24 to stop the push button member 8 being pushed right out of the bore 6.

The self-locking washer 12 has a central aperture (not shown) for fitting over the plain outer surface 14 of the body part 4. This aperture is defined by the ends of inwardly flexing'finger members (not shown).

The push button switch 2 includes rotation preventing means in the form of a rubber washer 52. The rubber washer acts to prevent rotation of the push button switch 2 relative to the mounting panel 18. This stops potential vandals from pressing on the push button member 8 or on a flange part 54 of the body part 4 to rotate the body part 4 and thus twist or break electrical wires connected to the electrical contacts 40142. The rubber washer 52 also inhibits moisture penetration to the inside of the mounting panel 18.

Figure 6 shows seven of the push button switches 2 mounted in the mounting panel 18. The top six push button switches 2 are indicated by the illustrated numbers marked on the mounting panel 18, these numbers being 12, 14, 16, 18, 20, 22. These numbers could be the numbers of flats in a block of flats. The lowermost push button switch 2 is indicated by the word trade marked on the mounting panel 18Q Referring now to Figures 6 and 7, there is shown an alternative body part 4.Similar parts as in the previous drawings have been given the same reference numerals for ease of comparison and understanding. In Figures 7 and 8, the rotation preventing means is in the form of a flat 56 on the side of the body part 4. The flat 56 is such as to correspond with a complementary flat (not shown) on the aperture 16 in the mounting panel 18.

With the two flats engaging, rotation of the body part 4 of the push button switch 2 is prevented.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thus, for example, stop means other than the pin 20 may be employed.

Also, different types of electrical contacts 40,42 may be utilised for the spring loaded switch device 10.

Claims

1. A push button switch comprising a body part, a bore in the body part, a push button member which is mounted in the bore such that the push button member can slide backwards and forwards in the bore, a spring loaded switch device which connects to the body part and which biases the push button member such that the push button member is caused to return to a set outer position after it has been manually depressed to an inner position, and a self-locking washer, the body part having a plain outer surface over which the self-locking washer slides in order to secure the push button switch in a desired aperture in a mounting panel.

2. A push button switch according to claim 1 and including stop means for controlling the inward travel of the push button member.

3. A push button switch according to claim 2 in which the stop means is also for controlling the outward travel of the push button member.

4. A push button switch according to claim 3 in which the stop means comprises a pin which locates in a first aperture in the push button member and in a second aperture in the body part, the pin being fixed in the first aperture, and the second aperture being larger than the first aperture so that the inner and the outer positions of the push button member are determined by the pin engaging on opposite side portions of the second aperture.

5. A push button switch according to claim 4 in which the second aperture is of such a size that the outer position of the push button member is always flush with a face of the body part.

6. A push button switch according to claim 4 or claim 5 in which the pin is a rolled spring metal pin.

7. A push button switch according to any one of the preceding claims in which the body part and the push button member are both circular in cross section.

8. A push button switch according to claim 7 in which the bore has first, second and third sections of progressively decreasing diameter, and in which the push button member has first and second sections of progressively decreasing diameter, the first and second sections of the push button member being such as to fit in the first and the second sections of the bore.

9. A push button switch according to any one of the preceding claims in which the spring loaded switch device has a plastics housing and a pair of electrical contacts.

10. A push button switch according to any one of the preceding claims in which the self-locking washer is a washer having inwardly flexing finger members.

11. A push button switch according to any one of the preceding claims and including rotation preventing means for preventing rotation of the push button switch in the mounting panel.

12. A push button switch according to claim 11 in which the rotation preventing means is a rubber washer for locating over the body part between the self-locking washer and the mounting panel.

13. A push button switch according to any one of claims 1 to il in which the rotation preventing means is a flat on the side of the body part, the flat being such as to correspond with a complementary flat on the aperture in the mounting panel.

14. A push button switch substantially as herein described with reference to the accompanying drawings.

15. The combination of a push button switch as claimed in any one of the preceding claims, and the mounting panel.

16. The combination according to claim 15 in which there are a plurality of the push button switches mounted in the mounting panel.