GB2254961A - Plunger switch with displaceable stop means - Google Patents
Plunger switch with displaceable stop means Download PDFInfo
- Publication number
- GB2254961A GB2254961A GB9107959A GB9107959A GB2254961A GB 2254961 A GB2254961 A GB 2254961A GB 9107959 A GB9107959 A GB 9107959A GB 9107959 A GB9107959 A GB 9107959A GB 2254961 A GB2254961 A GB 2254961A
- Authority
- GB
- United Kingdom
- Prior art keywords
- plunger
- switch
- housing
- movement
- plug
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/04—Stops for limiting movement of members, e.g. adjustable stop
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
- B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
- B60Q1/44—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating braking action or preparation for braking, e.g. by detection of the foot approaching the brake pedal
- B60Q1/441—Electric switches operable by the driver's pedals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H3/00—Mechanisms for operating contacts
- H01H3/02—Operating parts, i.e. for operating driving mechanism by a mechanical force external to the switch
- H01H3/16—Operating parts, i.e. for operating driving mechanism by a mechanical force external to the switch adapted for actuation at a limit or other predetermined position in the path of a body, the relative movement of switch and body being primarily for a purpose other than the actuation of the switch, e.g. for a door switch, a limit switch, a floor-levelling switch of a lift
- H01H3/166—Self-adjusting mountings, transmissions and the like
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S200/00—Electricity: circuit makers and breakers
- Y10S200/22—Strain relief, shear pin
Description
22-34961 SWITCHES The present invention relates to switches and in
particular to pedal box switches, ie. stop lamp switches, for motor vehicles, but may be used in other applications where there is requirement for the switch to operate in response to movement of a component.
A stop lamp switch for a motor vehicle is required to operate in response to a small movement of the brake pedal, typically 4 mm at the.switch. The switch includes a plunger which engages the pedal or a bracket attached thereto and is depressed thereby when the pedal is in its rest position. In order that the switch operates within the required range of movement of the pedal, the switch must be positioned accurately, so that upon movement of the pedal the plunger will move with it until electrical contacts come into engagement. Hitherto, the plunger, which is located through a necktube defined by the switch housing, has been dimensioned so that when the switch is correctly located, the plunger will be depressed fully into the necktube when the pedal is in its rest position, the pedal or a bracket attached thereto engaging against the end of the necktube. In this manner, the switch may be correctly located so that the contacts are brought into engagement after the desired amount of movement of the pedal.
If however the brake pedal returns beyond its normal rest position, due for example to wear or tolerance build up, loads in excess of 40ON may be applied to the end of the necktube which may dislodge the switch. As a result, the switch may become inoperative, the brake lamps being left permanently on when the pedal returns to its normal rest position. This problem is particularly prevalent on vehicles where a cross shaft transfers brake pedal effort across the vehicle to a brake booster mounted on the opposite side of the vehicle to the driver. Such systems suffer from inherent tolerance build up in the mounting bushes and joints, which allow the brake pedal to be lifted beyond its normal rest position.
According to one aspect of the present invention, a switch comprises; a switch housing, a plunger located within the switch housing, one end of the plunger extending out of the housing, the plunger being capable of limited movement relative to the housing, an electrical contact being provided on the plunger, said electrical contact being adapted to engage ari-.-electrical contact associated with the housing at an outward limit of movement of the plunger relative to the housing, stopmeans being provided coaxially of the plunger for engagement of the end of the plunger remote from said one end at a normal inward limit of movement of the plunger relative to the housing, said stop means being displaceable axially when a load in excess of a - 3 predetermined magnitude is applied thereto by the plunger, movement of the stop means permitting movement of the plunger beyond its normal inward limit of movement relative to the housing.
With the switch according to the present invention, the switch may be correctly located with respect to the brake pedal at its normal rest position, by locating the switch such that when the end of the plunger extending from the switch housing engages the pedal at its rest position, the remote end of the plunger engages the stop means. If the pedal now returns beyond its normal rest position so that the load applied to the stop means exceeds the predetermined value, the stop means will be displaced axially permitting the plunger to move beyond its normal inward limit, so that the additional rearward movement of the pedal may be accommodated without the switch housing being displaced. When the pedal returns to its normal rest position, the gap between the electrical contact on the plunger and that on the switch housing will remain, so that the switch will operate normally.
An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 illustrates in sectional elevation a vehicle brake lamp switch in accordance with the present invention; - 4 Figure 2 is a partial sectional view of the switch illustrated in Figure 1 in relation to a brake pedal in its normal rest position; and Figure 3 is a view similar to Figure 2 showing the brake pedal displaced rearwardly beyond its normal rest position.
As illustrated in Figure 1, a stop lamp switch 10 has a switch housing 11. A plunger 12 is located within the housing 11 coaxially of a necktube 13 defined by the housing 11, one end 14 of the plunger extending from the end of the necktube 13. A compression spring 15 acts between a shoulder 16 on the plunger 12 adjacent end 13 thereof and the housing 11 to urge the plunger 12 outwardly of housing 11.
An electrical contact 17 is provided on the inner end 18 of plunger 12 and contacts 19 and 20 mounted on housing 11 are arranged to be engaged by the contact 17 and to limit movement of the plunger 12 outwardly of the housing 11.
A plug 25 is mounted coaxially of the plunger 12 through an aperture 26 in the end wall of housing 11 remote from the necktube 13. The plug 25 is retained in position with respect to the housing 11 by means of a rib 27 which surrounds the aperture 26 and engages in a circumferential groove 28 in the plug 25. The plug 25 is displaceable axially relative to the housing 11 away from plunger 12, when a predetermined load, for example 70N, is applied to the inner end of plug 25, this load being sufficient to force the rib 27 out of engagement with the groove 28.
A second circumferential groove 30 is provided adjacent the inner end of plug 25 to retain the plug 25 in engagement with the housing 11 after it has been displaced axially.
As illustrated in Figures 2 and 3, serrations 35 are provided on the external diameter of the necktube 13. The necktube 13 is located through a bush 36 secured with respect to the vehicle in juxtaposed relationship to a bracket 37 secured to brake pedal 38. To correctly locate the stop switch 10 with respect to the brake pedal 38 when in its normal rest position, as illustrated in Figure 2, the necktube 13 is inserted through bush 36 until end 14 of plunger 12 engages the bracket 37. The plunger 12 is then depressed into the necktube 13 until the end 18 of plunger 12 engages the plug 25 which is located in the position illustrated in Figure 1. In this position, the gap between the contact 17 and contacts 19 and 20 is accurately set at, for example, 4 mm. The switch 10 is then rotated to bring the serrations 35 into engagement with complementary formations on the bush 36, is - 6 to clamp the switch 10 axially with respect to the bush 36. When the brake is now applied, movement of the pedal 38 away from switch 10 will permit the plunger 12 to move outwardly of housing 11, until contact 17 engages contacts 19 and 20 to make the brake lamp circuit. Upon release of the brake pedal 38, the plunger 12 will be depressed into the housing 11 causing contact 17 to move out of engagement with contacts 19 and 20, breaking the brake lamp circuit.
If the brake pedal 38 returns beyond its normal rest position, as illustrated in Figure 3, and the load applied to plug 25 by engagement with the plunger 12 exceeds the predetermined load, the plug 25 will be displaced axially rearwardly, permitting further rearward movement of plunger 12 to accommodate the excess movement of the pedal 38. The switch 10 may thus accommodate the excess rearward travel of pedal 38 without being displaced, so that when the pedal 38 returns to its normal rest position, the plunger 12 will return to its set position so that the required gap between contacts 17 and 19 and 20 is maintained.
If the switch 10 is removed for any reason, the plug 25 may be reset in its original position, as illustrated in Figure 1, so that when refitting the switch 10, the switch 10 may again be accurately located as described above.
Various modifications may be made without departing from the invention. While the present invention is particularly suitable for switches which are secured in position by bush means as described above, it may also be used with other means of securing the switch. For example where more rigid means of securing the switch are used, the present invention may avoid damage to the switch. Furthermore other forms of stop means may be used with appropriate means of controlling the load at which such stop means may be displaced.
X
Claims (7)
1. A switch comprising a switch housing, a plunger located within the switch housing, one end of the plunger extending out of the housing, the plunger being capable of limited movement relative to the housing, an electrical contact being provided on the plunger, said electrical contact being adapted to engage an electrical contact associated with the housing at an outward limit of movement of the plunger relative to the housing, stop means being provided coaxially of the plunger for engagement of the end of the plunger remote from said one end at a normal inward limit of movement of the plunger relative to the housing, said stop means being displaceable axially when a load in excess of a predetermined magnitude is applied thereto by the plunger, movement of the stop means permitting movement of the plunger beyond its normal inward limit of movement relative to the housing.
2. A switch according to Claim 1 in which the plunger is located coaxially of a necktube defined by the switch housing, one end of the plunger extending from the neck tube, the other end of the plunger being adapted to engage a plug located coaxially of the plunger through a wall of the switch housing, the plug in one position defining the normal inward limit of travel of the plunger and being displaceable axially when a load in excess of said predetermined magnitude is applied thereto to permit movement of the plunger inwardly beyond its normal inward limit of movement.
3. A switch according to Claim 2 in which the plug locates through an aperture in the wall of the switch housing, the aperture being surrounded by an annular rib which engages in a circumferential groove in the plug.
4. A switch according to Claim 3 in which a second annular groove is provided adjacent the inner end of the plug.
5. A switch according to any one of Claims 2 to 4 in which the switch is located in an operative position by means of a bush, the necktube of the switch being located through the bush, formations on the necktube being provided to engage with corresponding formations on the bush to locate the necktube axially with respect to the bush.
6. A switch according to any one of the preceding claims in which the plunger is resiliently loaded outwardly.
7. A switch substantially as described herein with reference to, and as shown in, Figures 1 to 3 of the accompanying drawings.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9107959A GB2254961A (en) | 1991-04-15 | 1991-04-15 | Plunger switch with displaceable stop means |
EP92303014A EP0509692B1 (en) | 1991-04-15 | 1992-04-09 | Switches |
DE69202910T DE69202910T2 (en) | 1991-04-15 | 1992-04-09 | Switch. |
US07/868,605 US5224588A (en) | 1991-04-15 | 1992-04-14 | Plunger switch providing relief for an excess plunger load |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9107959A GB2254961A (en) | 1991-04-15 | 1991-04-15 | Plunger switch with displaceable stop means |
Publications (2)
Publication Number | Publication Date |
---|---|
GB9107959D0 GB9107959D0 (en) | 1991-05-29 |
GB2254961A true GB2254961A (en) | 1992-10-21 |
Family
ID=10693271
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9107959A Withdrawn GB2254961A (en) | 1991-04-15 | 1991-04-15 | Plunger switch with displaceable stop means |
Country Status (4)
Country | Link |
---|---|
US (1) | US5224588A (en) |
EP (1) | EP0509692B1 (en) |
DE (1) | DE69202910T2 (en) |
GB (1) | GB2254961A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19921552C2 (en) * | 1999-05-11 | 2002-04-18 | Zf Lemfoerder Metallwaren Ag | Operating pedal for the brake system of a road vehicle |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB409075A (en) * | 1931-12-23 | 1934-04-26 | Gen Electric | Improvements in and relating to electric retractive switches with delayed return |
GB409510A (en) * | 1932-05-07 | 1934-05-03 | Gen Electric | Improvements in and relating to electric retractive switches with delayed return |
GB2068665A (en) * | 1980-01-21 | 1981-08-12 | Jaeger | Vehicle brake lamp monitoring device |
GB2077505A (en) * | 1980-06-03 | 1981-12-16 | Cherry Electrical Prod | Switch with wiping contact action |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR744372A (en) * | 1931-11-09 | 1933-04-19 | ||
US3624330A (en) * | 1970-05-01 | 1971-11-30 | Trw Inc | Telescoping switch |
US4154996A (en) * | 1977-05-12 | 1979-05-15 | Mcgraw-Edison Company | Positive break snap action switch |
US5031737A (en) * | 1990-01-29 | 1991-07-16 | General Motors Corporation | Transmission/brake interlock |
-
1991
- 1991-04-15 GB GB9107959A patent/GB2254961A/en not_active Withdrawn
-
1992
- 1992-04-09 DE DE69202910T patent/DE69202910T2/en not_active Expired - Fee Related
- 1992-04-09 EP EP92303014A patent/EP0509692B1/en not_active Expired - Lifetime
- 1992-04-14 US US07/868,605 patent/US5224588A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB409075A (en) * | 1931-12-23 | 1934-04-26 | Gen Electric | Improvements in and relating to electric retractive switches with delayed return |
GB409510A (en) * | 1932-05-07 | 1934-05-03 | Gen Electric | Improvements in and relating to electric retractive switches with delayed return |
GB2068665A (en) * | 1980-01-21 | 1981-08-12 | Jaeger | Vehicle brake lamp monitoring device |
GB2077505A (en) * | 1980-06-03 | 1981-12-16 | Cherry Electrical Prod | Switch with wiping contact action |
Also Published As
Publication number | Publication date |
---|---|
US5224588A (en) | 1993-07-06 |
EP0509692B1 (en) | 1995-06-14 |
GB9107959D0 (en) | 1991-05-29 |
DE69202910T2 (en) | 1995-11-02 |
DE69202910D1 (en) | 1995-07-20 |
EP0509692A1 (en) | 1992-10-21 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |