US3760135A

US3760135A - Seat belt safety switch with overcenter snap acting contact engaging belt actuating means

Info

Publication number: US3760135A
Application number: US00242952A
Authority: US
Inventors: L Nevett
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1971-04-13
Filing date: 1972-04-11
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18
Also published as: JPS4848962A; IT954423B; AU4104672A; GB1360854A; DE2217443A1; FR2143649A1; FR2143649B1; AU459299B2; JPS5320660B2

Abstract

An electrical switch for use with a vehicle safety harness has an insulating body through which a web of the harness passes. The body contains a resilient moving contact spring engageable with a hole in the web. The contact spring is biased by its own overcentering snap action to either of two stable positions, in one of which it engages a fixed contact to complete a circuit.

Description

United States Patent 1191 d 1111 3,760,135

Nevett Sept. 18, 1973 SEAT BELT SAFETY SWITCH WITH [56] References Cited OVERCENTER SNAP ACTING CONTACT UNITED STATES PATENTS ENGAGING BELT AGTUATING MEANS 3,381,268 4/1968 Boblitz zoo/61.13 x [75] Inventor, Lesne James New, (in-meme, 2,868,914 1/1959 Gleason 200/67 R x England [7 3] Assignee: Joseph Lucas (Industries) Limited, Pmnary [hammer-J Scott 7 Birmingham, Englan WWWWUMMMM a i221 Filed: Apr. 11, 1972 57 I I ABSTRACT [21] Appl. No.2 242,952 4 An electrical switch for use with a vehicle safetyharness has an insulating body through which a web of the [30] Foreign Application Priority Data harness passes. The body contains a resilient moving 1 contact spring engageable with a hole in the web. The 1 contact spring is biased by its own over-centering snap Us Cl 200/6158]; 200/6113 ZOO/67R factiontoeitheroftwostablepositions,inoneofwhich Apr. 13, 197i Great Britain 9,268/71 Int Cl "01h it engages a fixed contact to complete a circuit. [58] Field in Search ZOO/61.13, 61.18, A

2 0 0 6 l .58 B, 67 R, 67 D, 67 DB, 67 PK; 8 Claims, 8 Drawing Figures 307/105 B; 340/52 E; 180/82 C PATENTEDSEPIBIQYS 3, 5 ,135

SHEET 3 0F 3 n7 5 H6 nas u? FIGS. 114

1 SEATHBELT SAFETY swn'cn WITH ovancsursn SNAP ACTING CONTACT ENGAGING BELT. ACTUATING MEANS This invention relates to electrical switches for use in road vehicle safety arrangements and has particular reference to switches which are actuated by the withdrawal of more than a predetermined length of a safety belt from a belt storage reel.

A switch in accordance with the invention comprises a body having a passage therethrough to receive a belt,

a movable contact member mounted in the body and having a portion projecting into the passage for engagement by an abutment on a belt extending therethrough, the contact member being resiliently biased and arranged to occupy either one of two stable positions between which it can be displaced by movement of an abutment through the passage in opposite directions respectively and fixed contact means in the body engaged by the contact member in one of its stable positions.

In the accompanying drawings: r r

FIG. 1 is a section through an example of a switch, in accordance with the invention;

FIG. 2 is a section on line 2-2 in FlG l;

FIG. 3 is an electrical circuit diagram showing a vehicle safety arrangement incorporating the switch;

FIG. 4 is a section like FIG. 1 but showing another example of a switch in accordance with the invention;

FIG. 5 is a section on line 5-5 in FIG. 4;

FIG. 6 is an elevation onarrow A in'FIG. 5, and

FIGS. 7 and Sam sections of two alternative forms of belt abutments which can be used in connection with the switches, described.

The switch shown comprises a bodyformed in three partsl0, l1 and 12. The part 11 fits into the part which has a slot 13 at each end so that a passage through the body is formed between the parts 10 and 11 and opening to the exterior of the body through the slots 13. The passage is shaped and dimensioned to receive a safety belt 14 of material such as nylon. A spring plate 15 is positioned in the passage and has spring tongues urging the belt against the part 11 of the body. v

The body part 11 has a slot 16 through which a portion 17 of a movablecontact member 18, located between the body parts Hand 12, projects into the passage, The contact member is in the form of a V-shaped length of resilient conductive wire with the projecting portion 17 of U-shaped form at the apex of the V. The

body part 11 has a pair of recesses 19 into which the ends of the member 18 project. These recesses are shaped to deform the member 18 by flattening the V- shape thereof by an amount varying with the orientation of the member 18. When the member 18 occupies the position shown the V is least flattened but as the member 18 is turned in anticlockwise direction about an axis defined by the end of its two limbs, the V is increasing flattened until the plane of the member-l8 is perpendicular to the plane of the body part 12. Thereafter, the flattening of the member 18 progressively decreases. It will thusbe seen that a form of snap-action occurs, displacement of the member 18 being limited in opposite directions by a fixed contact abutment 20 on the part 12 and a further abutment 21 on the part 12.

The contact abutment 20 is integrally connected to a blade 22 fomiing a terminal of the switch. Another such blade 23, forming the other terminal, extends along the part 12 and the end of one limb of the member 18 rests permanently on it. Thus the

blades

22, 23 are electrically interconnected by the member 18 when it occupies the position shown, but are not interconnected when the member 18 engages the abutment 21.

For co-acting with the portion 17 of the member 18, the belt 14 is provided with an abutment, in this case formed by the ends of a hole 24 through the belt. Thus when the belt is passed through the passage in the body in one direction (i.e. to the left as viewed in FIG. 2) the abutment 24 turns the member 18 to its off position in which it engages the abutment 21. When the belt is passed in the other direction the abutment 24 turns the member 18 to its on position in engagement with the contact abutments 20.

In use the switch is mounted adjacent a belt reel of a .:vehicle safety harness, arranged so that the belt passes through the switch body in the foresaid one direction as the belt is withdrawn from the reel. The hole 24 is made in the belt at, a position such that it passes thorugh the switch body after sufficient belt has been withdrawn to pass around an unoccupied seat, but before sufficient is withdrawn to pass around a child in the seat. There are, in fact, two of the switches .provided for the drivers and the front, passengers belts respectively. These two switches are indicated in FIG. 3 by

reference numerals

25, 26, respectively. I

I The circuit shown includes a gearselector operated I switch 27 which is closed when a drive gear is selected and is open when neutral is selected. This switch 27 is connected via the ignition switch 28 to one terminal of the battery 29. A switch 30 is provided for sensing the presence of a passenger in the passenger seat and is open when the passenger seat is unoccupied. A warning light device 31 and an audible warning device 32 are connected in parallel. The

switches

25, 27 and 28 form one series circuit between the battery 29 and the

warning devices

31 and 32 so that if all three switches are closed simultaneously the warning devices are energized. The

switches

30 and 26 are connected in series across the switch 25.

Thus, whenever the ignition is switched on and a drive gear is selected, the

warning devices

31 and 32 will be energized if a. the drivers belt is not with-drawn sufficiently to open the switch 25, or

b. the passenger seat is occupied and the corresponding belt is not sufficiently withdrawn to open the switch 26.

In the alternative embodiment of the invention shown in FIGS. 4 to 6 the switch body is in the form of a one-piece molding in a flexible synthetic resin material comprising two body parts and 111 joined together by a pair of integral flexible straps 1 12 bent over through 180 to bring the two parts 110, 111 into interengagement. A passage 113 for the belt 114 is defined between the parts 110 and 111 and integral spring portions 115 of the part 110 urge the belt 114 onto shoulders 116 on the part 111. A pair of integral undercut clip portions 117 are provided on the end of the part 110 remote from the straps 112 and these coact, with shoulders 118 on the part 111 to hold the two parts in interenga'gement. Accurate location of the two parts relative to one another is achieved by means of a pair of spigot portions 119 on the part 111 which fit into sockets 120 on the part 110. In fact, there are drillings through the spigot portion 119 through which fixing bolts are inserted in use to secure the switch in position and these bolts will prevent separation of the parts 110 and 111 independently of the clip portions 117.

There are two

fixed contacts

121 and 122 each of which has a tenninal blade projecting from the body. A movable contact 123 has one end captive in an integral bowed spring portion 124 so that its opposite end is urged into contact with one side of the belt 114. Since the belt 114 is held in tension by a rewinding reel the contact 123 will have a toggle action between two

stops

125 and 126 provided on the part 111. The

contacts

121, 122 are associated with the stop 126 so that these are interconnected by the contact 123 when the switch occupies the position shown with the contact 126 engaging the stop 126.

Thus the switch is arranged and used as in the example described inconnection with FIGS. 1 to 3 of the drawings.

As shown in FIG. 7 the abutment on the belt may be in the form of a plate 201 welded, rivetted or otherwise attached to the belt. Alternatively, as shown in FIG. 8, the abutment may simply be a metal staple 301 of shallow V-shaped configuration with its ends extending through the belt and bent over in well known manner.

I claim: 1

1. A switch comprising a body having a pasage therethrough to receive a belt, a resiliently deformable movable contact member mounted in the body and having a portion projecting into said passage for engagement byan abutmentflon a belt extending through said passage, means within the body for locating said member in either one of two positions between which it can be displaced by movement of said abutment through said passage in opposite directions respectively, said member being reiliently deformed by said body during said movement so as to provide an over-centering action, whereby each said position is a stable position, and fixed contact means in the body engaged by said contact member in one of its stable positions.

2. A switch as claimed in claim 1 in which said movalbe contact member is formed of resilient conductive wire.

3. A switch as claimed in claim 2 in which said wire is of generally V-shaped configuration said projecting portion being at the apex of the V.

4. A switch as claimed in claim 1 in which said body has a resilient bowed spring portion with which said movable contact member is engaged.

5. A switch as claimed in claim 1 in combination with a seat belt passing through said passage in said body and having an abutment thereon for co-acting with said movable contact members.

6. A switch and seat belt combination as claimed in claim 5 in which said abutment is formed by an aperture in said belt.

7. A switch and seat belt combination as claimed in claim 5 in which said abutment is formed by a plate attached to said belt.

- 8. A switch and seat belt combination as claimed in claim 5 in which said abutment is a metal staple of shal-

Claims

1. A switch comprising a body having a pasage therethrough to receive a belt, a resiliently deformable movable contact member mounted in the body and having a portion projecting into said passage for engagement by an abutment on a belt extending through said passage, means within the body for locating said member in either one of two positions between which it can be displaced by movement of said abutment through said passage in opposite directions respectively, said member being reiliently deformed by said body during said movement so as to provide an over-centering action, whereby each said position is a stable position, and fixed contact means in the body engaged by said contact member in one of its stable positions.

8. A switch and seat belt combination as claimed in claim 5 in which said abutment is a metal staple of shallow V-shaped configuration.